handbook of specialty elastomers - robert c_ klingender

Handbook of

SPECIALTYELASTOMERS

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page i 23.10.2007 7:54pm Compositor Name: TSuresh

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page ii 23.10.2007 7:54pm Compositor Name: TSuresh

CRC Press is an imprint of theTaylor & Francis Group, an informa business

Boca Raton London New York

Handbook of

SPECIALTYELASTOMERS

Edited byRobert C. Klingender

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page iii 23.10.2007 7:54pm Compositor Name: TSuresh

CRC PressTaylor & Francis Group6000 Broken Sound Parkway NW, Suite 300Boca Raton, FL 33487-2742

2008 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business

No claim to original U.S. Government worksPrinted in the United States of America on acid-free paper10 9 8 7 6 5 4 3 2 1

International Standard Book Number-13: 978-1-57444-676-0 (Hardcover)

This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the conse-quences of their use.

No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers.

For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged.

Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe.

Library of Congress Cataloging-in-Publication Data

Klingender, Robert C.Handbook of specialty elastomers / Robert C. Klingender.

p. cm.Includes bibliographical references and index.ISBN 978-1-57444-676-0 (alk. paper)1. Elastomers--Handbooks, manuals, etc. I. Title.

TS1925.K46 2007620.194--dc22 2007020182

Visit the Taylor & Francis Web site athttp://www.taylorandfrancis.comand the CRC Press Web site athttp://www.crcpress.com

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page iv 23.10.2007 7:54pm Compositor Name: TSuresh

ContentsPreface .................................................................................................................... viiEditor....................................................................................................................... ixContributors ........................................................................................................... xi

Chapter 1 Polychloroprene Rubber .................................................................... 1

Rudiger Musch and Hans Magg

Chapter 2 Acrylonitrile Butadiene Rubber....................................................... 39

Robert C. Klingender

Chapter 3 Hydrogenated Nitrile Rubber .......................................................... 93

Robert W. Keller

Chapter 4 Fluoroelastomers, FKM, and FEPM ............................................. 133

Pascal Ferrandez

Chapter 5 Polyacrylate ElastomersProperties and Applications ................ 155


Chapter 6 Ethylene=Acrylic (AEM) Elastomer Formulation Design............. 193

Lawrence C. Muschiatti, Yun-Tai Wu, Edward McBride,and Klaus Kammerer

Chapter 7 Polyepichlorohydrin Elastomer ..................................................... 245


Chapter 8 Compounding with Chlorinated Polyethylene .............................. 289

Ray Laakso

Chapter 9 Chlorosulfonated Polyethylene and AlkylatedChlorosulfonated Polyethylene...................................................... 301


Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page v 23.10.2007 7:54pm Compositor Name: TSuresh

v

Chapter 10 Ethylene Vinyl Acetate Elastomers (EVM)(ASTM Designation AEM) ........................................................... 343

Hermann Meisenheimer and Andrea Zens

Chapter 11 Polysulde Elastomers................................................................... 369

Stephen K. Flanders and Robert C. Klingender

Chapter 12 Plasticizers, Process Oils, Vulcanized Vegetable Oils .................. 387

Peter C. Rand

Chapter 13 Vulcanization Agents for Specialty Elastomers ............................ 409

Robert F. Ohm

Chapter 14 Antioxidants for Specialty Elastomers .......................................... 429

Russell A. Mazzeo

Chapter 15 Processing Aids for Specialty Elastomers ..................................... 477

Jerry M. Sherritt

Chapter 16 Considerations in the Design of a Rubber Formulation................ 493


Part A: Oil Field Elastomeric Products ....................................... 495


Part B: Life Prediction................................................................. 515

John Vicic

Part C: Compression, Transfer, and Injection Moldingof Specialty Elastomers................................................... 519

Robert W. Keller

Index ..................................................................................................................... 543

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page vi 23.10.2007 7:54pm Compositor Name: TSuresh

vi

PrefaceTheHandbook of Specialty Elastomerswas conceived as a single reference source forthe rubber compounder with some experience in designing parts in the rubberindustry. The denition of specialty elastomers referenced in this publication is heat,oil, fuel, and solvent-resistant polymers that include polychloroprene (CR), nitrilerubber (NBR), hydrogenated nitrile rubber (HNBR), uoroelastomer (FKM), poly-acrylate (ACM), ethylene acrylic elastomer (AEM), polyepichlorohydrin (CO, ECO),chlorinated polyethylene (CPE), chlorosulfonated polyethylene (CSM), ethylenevinyl acetate (EAM), and thiokol (T).

In addition to the information on the specialty elastomers, chapters on the moreimportant ingredients used with them are included. These are plasticizers, vulcan-ization agents, antioxidants and antiozonants, and process aids.

The nal chapter, in three sections, provides one example of industry require-ments for rubber parts, considerations to be made concerning the life expectancy ofelastomer compounds and processing factors to be taken into account in the moldingoperation of a rubber factory.

It is the desire of the editor and contributing authors that this book provide acomprehensive insight into the process of designing rubber formulations based onspecialty elastomers.

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page vii 23.10.2007 7:54pm Compositor Name: TSuresh

vii

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page viii 23.10.2007 7:54pm Compositor Name: TSuresh

EditorRobert C. Klingender, a graduate of the University of Toronto with a BAScdegree in chemical engineering, is retired after serving over 54 years in the rubberindustry. During that time he worked at Gutta Percha & Rubber Ltd., a mechanicalrubber goods manufacturer, as assistant chief chemist; Polysar Ltd., a synthetic rubberproducer, as technical service manager, technical service and sales district manager,technical director of custom mixing; Goldsmith & Eggleton, a distributor for NipponZeon, as vice president, technical products; and Zeon Chemicals, LLC, a syntheticrubber producer in various technical sales and marketing functions. Bobs careerfocused on specialty elastomer applications in the mechanical and automotiveproducts industries.

Service to the rubber industry has been Klingenders passion over the years,having served in many capacities in the Rubber Division, ACS as well as theChicago, Wisconsin, Twin Cities and Northeast Ohio rubber groups.

In his various capacities, Klingender authored or coauthored over 15 technicalpapers for the Rubber Division, ACS and various local rubber groups. In additionhe wrote some 25 technical bulletins and contributed a chapter on MiscellaneousElastomers to Rubber Technology, third edition, edited by Maurice Morton.

After retirement Robert has concentrated more on golf (with not too muchsuccess), playing bridge, and gourmet cooking (a skilled rubber compounder canalso work well with food recipes).

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page ix 23.10.2007 7:54pm Compositor Name: TSuresh

ix

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page x 23.10.2007 7:54pm Compositor Name: TSuresh

Contributors

Pascal FerrandezDuPont Performance Elastomers, LLCWilmington, Delaware, U.S.A.

Stephen K. Flanders (Deceased)Morton International, Inc.Woodstock, Illinois, U.S.A.

Klaus KammererDuPont Performance ElastomersInternational S.A.

Geneva, Switzerland

Robert W. KellerConsultantLexington, Kentucky, U.S.A.

Robert C. KlingenderSpecialty Elastomer ConsultingArlington Heights, Illinois, U.S.A.

Ray LaaksoThe Dow Chemical CompanyPlaquemine, Lousiana, U.S.A.

Hans MaggBayer CorporationLeverkusen, Germany

Russell A. MazzeoMazzeo EnterprisesWaterbury, Connecticut, U.S.A.

Edward McBrideDuPont Packaging and IndustrialPolymers

Wilmington, Delaware, U.S.A.

Hermann Meisenheimer (Retired)Bayer CorporationLeverkusen, Germany

Rudiger Musch (Retired)Bayer CorporationLeverkusen, Germany

Lawrence C. MuschiattiDuPont Performance Elastomers LLCWilmington, Delaware, U.S.A.

Robert F. OhmLion Copolymer, LLCBaton Rouge, Louisiana, U.S.A.

Peter C. RandMerrand International CorporationPortsmouth, New Hampshire, U.S.A.

Jerry M. Sherritt (Retired)Struktol CompanyBarberton, Ohio, U.S.A.

John VicicWeatherford International, Inc.Houston, Texas, U.S.A.

Yun-Tai WuDuPont Packaging and IndustrialPolymers

Wilmington, Delaware, U.S.A.

Andrea ZensBayer CorporationLeverkusen, Germany

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page xi 23.10.2007 7:54pm Compositor Name: TSuresh

xi

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C000 Final Proof page xii 23.10.2007 7:54pm Compositor Name: TSuresh

1 PolychloropreneRubber

Rudiger Musch and Hans Magg

CONTENTS

1.1 Introduction...................................................................................................... 21.2 History, Polymerization, Structure, and Properties ......................................... 2

1.2.1 History ............................................................................................... 21.2.2 Chloroprene Monomer Production .................................................... 31.2.3 Polymerization and Copolymerization .............................................. 31.2.4 Structure and Structural Variables..................................................... 41.2.5 Structure and Properties..................................................................... 8

1.2.5.1 General Purpose Grades.................................................... 81.2.5.2 Precrosslinked Grades..................................................... 101.2.5.3 Sulfur-Modied Grades (S-Grades)................................ 10

1.2.6 Commercially Available CR Rubbers ............................................. 111.2.7 Compounding and Processing ......................................................... 14

1.2.7.1 Selection of Chloroprene Rubber Grades ....................... 141.2.7.2 Blends with Other Elastomers ........................................ 141.2.7.3 Accelerators .................................................................... 151.2.7.4 Antioxidants, Antiozonants............................................. 171.2.7.5 Fillers .............................................................................. 191.2.7.6 Plasticizers ...................................................................... 211.2.7.7 Miscellaneous Compounding Ingredients....................... 23

1.2.8 Processing ........................................................................................ 241.2.9 Properties and Applications ............................................................. 25

1.2.9.1 General ............................................................................ 251.2.9.2 Physical Properties.......................................................... 251.2.9.3 Aging and Heat Resistance............................................. 261.2.9.4 Low-Temperature Flexibility .......................................... 271.2.9.5 Flame Retardance............................................................ 281.2.9.6 Resistance to Various Fluids .......................................... 291.2.9.7 Resistance to Fungi and Bacteria ................................... 29

1.2.10 Applications ..................................................................................... 291.2.10.1 Hoses ............................................................................... 291.2.10.2 Molded Goods................................................................. 321.2.10.3 Belting ............................................................................. 34

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C001 Final Proof page 1 22.10.2007 3:34pm Compositor Name: BMani

1

1.2.10.4 Extruded Proles .............................................................. 341.2.10.5 Wire and Cable................................................................. 341.2.10.6 Miscellaneous ................................................................... 36

References ............................................................................................................... 36

1.1 INTRODUCTION

Polychloroprene was one of the rst synthetic rubbers and has played an importantrole in the development of the rubber industry as a whole, a fact that can be attributedto its broad range of excellent characteristics.

In terms of consumption, polychloroprene has become a most important specialtyrubber for non-tire applications.

1.2 HISTORY, POLYMERIZATION, STRUCTURE, AND PROPERTIES

1.2.1 HISTORY

The polychloroprene story started in 1925,with the synthesis of themonomer byFatherNieuwland [1]. The rst successful polymerization under economically feasible con-ditions was discovered in 1932 by Carothers, Collins, and coworkers using emulsionpolymerization techniques [2]. In the same year DuPont began marketing the polymerrst under the trade name Duprene and since 1938 as Neoprene. A wide range ofpolychloroprene grades has since been developed to meet changing market demands

1940 A breakthrough in 1939 due to the development of a copolymerwith sulfur (Neoprene GN) featuring more desirable viscosity andprocessing behavior

1950 Soluble, sulfur-free homo- and copolymers using mercaptans aschain transfer agents (M-grades) offering improved heat resistancewere invented and, in the case of copolymers, these had reducedtendency to crystallization (DuPont)

1960 Precrosslinked grades for improved processability, in particularwhere reduced nerve and die swell is of prime concern (DuPont)

1970 Precrosslinked and soluble grades with improved physical andmech-anical properties (DuPont)sulfur-modied grades with higher dynamic load-bearing capacityand better heat stability (DuPont)

1980 Commercially successful soluble homo- and copolymers using specialXanthogen-disuldes as chain modiers (XD-grades) with improvedprocessability and vulcanizate properties (Bayer AG=Distugil);soluble copolymers with excellent performance under adverse climaticconditions (extremely slow crystallization with a higher service tem-perature) (Bayer AG=Denki)

1990 Newly developed M- and XD-grades combining low-temperatureexibility, improved heat resistance, and dynamic properties as wellas low mold fouling (Bayer AG)


2 Handbook of Specialty Elastomers

Since 1933, when DuPont started up their rst production plant, several othercompanies have also joined the list of producers.

The current list of polychloroprene producers is shown in Table 1.1. Name platecapacity for all plants worldwide, former Soviet Union included, is estimated to be348,000 metric tons (2001). DuPont announced the closure of the Louisville, KYplant by 2005, reducing worldwide capacity by 64,000 metric tons.

1.2.2 CHLOROPRENE MONOMER PRODUCTION

From the very beginning up to the 1960s, chloroprene was produced by the olderenergy-intensive acetylene process using acetylene, derived from calcium car-bide [3]. The acetylene process had the additional disadvantage of high invest-ment costs because of the difculty of controlling the conversion of acetyleneinto chloroprene. The modern butadiene process, which is now used by nearly allchloroprene producers, is based on the readily available butadiene [3].

Butadiene is converted into monomeric 2-chlorobutadiene-1,3(chloroprene) via3,4-dichlorobutene-1 involving reactions that are safe and easy to control.

The essential steps in both processes are listed in Figure 1.1.

1.2.3 POLYMERIZATION AND COPOLYMERIZATION

In principle, it is possible to polymerize chloroprene by anionic-, cationic-, and ZieglerNatta catalysis techniques [4] but because of the lack of useful properties, produc-tion safety, and economical considerations, free radical emulsion polymerization is

TABLE 1.1Production Facilities for Chloroprene Rubber (IISRP Worldwide RubberStatistic 2001)

Company Location CountryCapacitya

(in Metric Tons)

DuPont Louisville USA 64,000Pontchartrain USA 36,000

Bayer AG Dormagen Germany 65,000

Denki Kagaku Omi Japan 48,000Enichem Champagnier France 40,000Showa Kawasaki Japan 20,000

Tosoh Shinnayo Japan 30,000Razinoimport Eravan Armenia 5,000Peoples Republic

of ChinabChang Zhou Peoples Republic

of China

5,000b

Daiton 10,000b

Qindau

a Latex and adhesive grades included.b Estimated by editor.


Polychloroprene Rubber 3

exclusively used today. It is carried out on a commercial scale using both batch andcontinuous processes.

A typical production ow diagram is shown in Figure 1.2.Chloroprene in the form of an aqueous emulsion is converted with the aid

of radical initiators into homopolymers or, in the presence of comonomers, intocopolymers [5].

Comonomers, which have been used with success, are those with chemicalstructures similar to that of chloroprene, in particular

1. 2,3-Dichloro-butadiene to reduce the crystallization tendency, that is, thestiffness of the chain.

2. Acrylic or methacrylic acid esters of oligo functional alcohols to producethe desired precrosslinked gel polymers.

3. Unsaturated acids, for example, methacrylic acid, to produce carboxylatedpolymers.

4. Elemental sulfur to produce polymer chains with sulfur segments in thebackbone, facilitating peptization.

1.2.4 STRUCTURE AND STRUCTURAL VARIABLES

Polychloroprene is highly regular in structure and consists primarily of trans-units;however, there are sufcient cis-units to disturb the backbone symmetry and maintaina rubbery state [6].

Therefore, the physical, chemical, and rheological properties of polychloropreneare, to a large extent, dependent on the ability to change the molecular structure,

Acetylene process (1930)AcetyleneCH=CH

CH=CCH=CH2

CH2=CCH=CH2

CH2=CHCH=CH2 + Cl2

=

CHClCH2Cl CHCH2Cl

CHCH2Clcis- andtrans-1.4-Dichlorobutene-2

HCl

Iso-merizationCH=CH2

3,4-Dichloro-butene-1

2-Chlorobutadiene-1,3 (b.p. 59.4C)

ChloropreneAdvantage

Disadvantages

AdvantagesLow cost feedstockSafer and more economical process

Waste salt solutionEffluent problems

DisadvantagesExpensive feedstockProcess difficult to control

Reduced effluent problems

Cl

Monovinyl-acetylene

+HCl

Butadiene process (1960)Butadiene

FIGURE 1.1 Acetylene and butadiene route to chloroprene.



for example, the cis=trans ratio, long chain branching, and the amount of cross-linking. Key roles in changing the molecular structure are played by

1. Polymerization conditions: polymerization temperature, monomer conver-sion, polymerization process [7]

2. Polymerization aids: concentration and type of chain modier, comonomers,and emulsier [8]

3. Conditions during nishing

Figure 1.3 compares the structural units of commercially available polychloro-prene. In this polymer the 1,4 addition [1], in particular the 1,4-trans-addition (lb),is dominant. In addition, small proportions of the 1,2-(II) and 3,4-(III) structures arealso present. These polymer structures are combined in sequential isomers derivedfrom head to tail (IV), head to head (VI), and tail to tail (V) addition [9].

In addition, the preparation of stereoregular polychloroprene by unusual poly-merization conditions has demonstrated that the glass transition temperature andthe melting temperature of the polymer are inverse functions of polymerizationtemperature [10,11] as seen in Figure 1.4).

Using standard polymerization conditions, crystallization is an inherent propertyof all polychloroprene rubbers [12]. A homopolymer manufactured at 408C has atrans-1,4-content of ca. 90%, a degree of crystallization of ca. 12%, and a crystallinemelting temperature of ca. 458C. A reduction in the rate of crystallization is possible

Acid Rotating cooling drum

Coagulation by freezing

NeutralizationWashing

Dryer

Choppingmachine

Roping machine

Dustingmachine

Latex-concen-tration

Peptization

Stripper

Polymerization

Water

Chloro-prene

Regulator

Emulsifier

Purification

Unreacted monomer

Co-monomerRecycled monomer

FIGURE 1.2 Flow diagram for the polymerization and isolation of polychloroprene.



by either decreasing trans-1,4-content or increasing non-1,4-content or by introdu-cing comonomers. In practice, the latter is the easiest. The crystallinity in polychlo-roprene makes processing difcult and the vulcanizate increases in hardness withage. Therefore, polychloroprene polymers are normally produced at high polymeriz-ation temperatures (308C608C) or using additional comonomers interfering withcrystallization. Through such measures, the crystallizing tendency of polychloro-prene in both the raw and vulcanized states is reduced.

The crystallization process is temperature dependent and has its maxi-mum rate at 58C to 108C. This effect is responsible for the hardening andthe reduction in elasticity of chloroprene rubber (CR) polymer compounds andvulcanizates during storage at low temperatures. Crystallization is completelyreversible by heat or dynamic stress. In general, the raw polymers crystallize10 times faster than vulcanized, plasticizer-free compounds (ISO 2475, ASTM D3190-90).

Variations in microstructure are responsible for signicant changes in polymerproperties. Figure 1.5 shows the main modications of the polychloroprene chain

1. Structural isomers

Isomers of polychloroprene

2. Geometrical isomers

1,4-cis-addition (la)

3. Sequence isomers(IV) Head-to-tail (H/T)(V) Tail-to-tail (T/T)(VI) Head-to-head (H/H)

Freeradical

polymern H2C=CCH=CH2

Cl

(H2CC=CHCH2)(CH2C=CHCH2 )Cl

HCl

CH2H2CC=C

1,4 Adduct (I)~97%

1,2 Adduct (II)~1,5%

3,4 Adduct (III)~1,0%

(CH2C=CHCH2)x~~Cl

(CH2C )y~ ~Cl

CH=CH2

][(CH2C )z~ ~

H

ClC=CH2

1,4-trans-addition (lb)

(CH2CH=CCH2)(CH2C=CHCH2 )

(H2CC=CHCH2)(CH2CH=CCH2 )

~~

~

~

~

~

{

H

Cl CH2

H2CC=C

][

Cl

Cl

Cl

Cl

Cl

FIGURE 1.3 Structural units in the polychloroprene chain (typical commercial rubber grade)crosslinking site.



Polymerization temperature (C)

Tg

(C)

Tm

(C

)

14050

40

30

20

10

0

10

20

30

40

50

60

70

80

90

120100 80 60 40 20 0 20 40 60 80 100 120

FIGURE 1.4 Glass transition temperature (Tg) and melt temperature (Tm) of polychloropreneprepared at various temperatures.

(a) Linear, configuration uniform Sulfur-modifiedR

RR

RRR

RR

R

RSx Sy

Precrosslinking

Crystallization resistant

Variations in MW and MW-distribution

Cl Cl Cl Cl

Cl Cl Cl

Cl Cl

x

x

(b) Linear, configuration nonuniform

(c) Branched, configuration nonuniform

(d) Linear, reactive endgroups

(e)

(f)

(g)

(h)

FIGURE 1.5 Modications of the polychloroprene chain.



1. Increasing trans-content with decreasing polymerization temperature givesincreasing crystallization tendency (adhesive grades).

2. Increasing 1,2- and cis-1,4-additions with increasing polymerization tempera-ture reduces crystallization and provides faster curing, necessary for rubbergrades (1,2-structures important for crosslinking with metal oxides).

3. Chain branching with high polymerization temperature and high monomerconversion results in reduced stability in polymer viscosity and processingproperties deteriorate.

4. Reactive end groups using XD-chain modier provide reduced branching,easy processing, and elastomers with more homogeneous networks, forexample, high tensile strength.

5. Polymer chains with sulfur atoms in multiple sequences ranging from 2 to 8show improved breakdown during mastication, outstanding tear resistance,and dynamic behavior.

6. Specially induced precrosslinking yields sol=gel type blends yielding process-ing and extrusion advantages with increasing gel content (10%50%).

7. Reduced stereoregularity using comonomers leads to reduced crystallizationtendency and level, thus the so called crystallization resistant grades.

8. Increasing molecular weight results in increasing the polymer viscosity andtensile strength of vulcanizates.

9. Increasing molecular weight distribution gives improved processability andreduced tensile strength.

1.2.5 STRUCTURE AND PROPERTIES

1.2.5.1 General Purpose Grades

1.2.5.1.1 Mercaptan-Modied (M-Grades)This group contains non-precrosslinked, sulfur-free, soluble, homo- and copolymersand is themost important in terms of the quantity used. It comprises the standard gradeswith polymer viscosities of approximately 30140 Mooney units (ML4 at 1008C) andslight to medium crystallization types. These grades are also known as mercaptangrades. Their property proles tend to be inuenced mainly by polymer viscosity.

Table 1.2 shows the changes in properties as a function of Mooney viscosity.Grades with slight to very slight crystallization should be used in parts intended

for low-temperature service. The inuence of crystallization tendency on polymerand elastomer properties is listed in Table 1.3.

1.2.5.1.2 Xanthogen-Disulde GradesXD-grades are produced with a special modier. Some of them are copolymerizedwith other monomers to produce copolymers that have only a medium or slighttendency to crystallization.

Processing behavior: They are generally less elastic (reduced nerve) thanM-grades and are, therefore, more easily processed by calendering or extrusion.Additionally, the ram pressure during mixing can be reduced and as a result thecompounds have greater scorch resistance.



Vulcanizate properties: If M-grades are substituted with XD-grades in a givenrecipe, vulcanizates with improved mechanical properties will result, that is, highertensile strength and tear.

Strength, rebound resilience, and resistance to dynamic stress are obtained. Theimportance of these differences is emphasized in Figure 1.6.

In contrast to M-grades, the tensile strength of vulcanizates based on XD-gradesis essentially independent of the viscosity of the starting material within a broad

TABLE 1.2Inuence of Mooney Viscosity

Mooney Viscosity Inuence

Low to high

Compatibility with llers and oilFiller dispersion in soft compoundsDimensional stability and shape retention

Green strength especially of heavilyloaded compoundsAir inclusion in soft molding compounds

Tensile strengthModulusCompression set

Mill bandingMixing temperatureEnergy consumption during mixing

Flow behaviorDie swellCalendering properties

Note: Direction of arrow denotes improvement.

TABLE 1.3Inuence of Crystallization on Properties

Crystallization Inuence

Slight to strong

Green strengthCohesive strength

Setting rate (adhesives)Tensile strengthModulusTack and building tack

Retention of rubberlike properties at lowtemperatures over long periods of time

Note: Direction of arrow denotes improvement.



viscosity range. This improved performance permits heavier ller and plasticizerloadings, thereby reducing compound cost.

More recently developed M- and XD-grades show reduced nerve, signicantreduction in mold fouling, higher tensile strength, better aging characteristics,signicantly improved dynamic properties, and better low-temperature behavior.

1.2.5.2 Precrosslinked Grades

Precrosslinked grades have proven particularly suitable for extruded and calenderedgoods and, in special cases, for injection molding. The precrosslinking that occursduring the production of the polymer improves processability, because it reduces theelasticity or nerve of the raw rubber and its compounds.

Typical characteristics are improved mill banding, low die swell, smooth sur-faces, excellent dimensional stability, and in the case of XD-precrosslinked grades,no decrease in tensile strength.

As the degree of precrosslinking rises, several properties of the compounds andvulcanizates change as shown in Table 1.4.

1.2.5.3 Sulfur-Modied Grades (S-Grades)

Sulfur-modied grades are obtained by copolymerization of chloroprene with smallamounts of sulfur, followed by peptization of the resulting copolymer in the pre-sence of tetra alkyl thiuram disulde. Sulfur is built into the polymer chains inshort sequences.

Sulfur modication improves the breakdown of the rubber during mastication,permitting the production of low-viscosity compounds with good building tack.Only zinc oxide and magnesium oxide are needed for vulcanization. In many cases

XD-Grade

1201101009080706050

Raw material Mooney viscosity ()

Tens

ile s

treng

th o

f vu l

c an i

z ate

(MPa

)

403017.0

18.0

19.0

20.0

21.0

M-Grade

FIGURE 1.6 Tensile strengthMooney viscosity relationship of M- and XD-modiedgeneral purpose grades (Recipe ISO 2475).



the vulcanizates have better tear resistance and adhesion to fabrics than those basedon general purpose grades.

Disadvantages: Polymers are less stable during storage and vulcanizates are lessresistant to aging.

Differences in the property prole of commercially available S-grades are causedby different combinations of sulfur level, comonomers, soap system, polymerizationand peptization reactions, and staining or nonstaining stabilizers.

More recently developed grades give elastomers with a higher tear propagationresistance, greater resistance to dynamic stress, and better aging behavior. They alsocause less mold fouling.

1.2.6 COMMERCIALLY AVAILABLE CR RUBBERS

Table 1.5 lists the most commonly used grades marketed in 2002 by the mainsuppliers in the western hemisphere [13]. The available grades are divided intothree groups: general purpose grades (non-precrosslinked), precrosslinked grades,and sulfur-modied grades.

TABLE 1.4Relationship between Precrosslinking and Properties

Crosslinking Increases

Properties of raw compounds

Processing properties in general(improvement is accompanied by loss of nerve)Mill banding

Die swellExtrusion rateDimensional stability and shape retention

Calender shrinkageSmoothness of extrudates and calendered sheetsDimensional stability of extrudates and calendered sheet

Air inclusion in soft compoundsFlow in injection molding(improvement depends on compounding)

Building tackSolubility in organic solvents

Vulcanizate properties

ModulusRebound resilience

Compression set (depends on type of compound)Tensile strengthElongation at break

Tear resistance

Note: Improvements in direction of arrow.



TABLE

1.5

CrossReference

ofPo

lychloropreneGrades

DuP

ont

Bayer

DenkiKagakuKogyo

Enichem

Show

aDDEMfg.

TOSO

HCorpo

ratio

n

Neoprene

Baypren

Denka

Chlorop

rene

Butaclor

Neoprene

Skyprene

Grade

ML4

Grade

ML4

Grade

ML4

Grade

ML4

Grade

ML4

Grade

ML4

General

Purpo

seGrades

Slow

CrystallizationTypes

WRT-M

138

110

45S-40V

48MC-10

45WRT

46B-5

49WRT-M

246

111

42B-5A

45

112

42S-40=41

48MC-20

46WX-J

46B-10

51116a

46MC-122

a43

B-11

49126a

70B-10H

75

WD

110

130

105

Medium


W49

210

45M-40=41

48MC-30

46W

46B-30

49WM-1

38211

39M-30=31

38MC-31

38WM-1

37B-31

40

216a

46MC-322

43P-90

45226a

75MC-323

59M-70

70WHV-100

97230

100

M-100

100

MH-31

94WHV-100

100

Y-31

100

WHV

115

M-120

120

MH-30

114

WHV

120

Y-30S

123



PrecrosslinkedGrades

Slow


114

62ES-70

75WXKT

110

WB

4 72 14

5 5ES-40

4 3WXK

8 0E-20 H

6 4TRT

4 72 15

5 0DE-10 2

4 8TRT

4 6E-20

4 8

Me dium

Cr ys ta lliza tionTy pe s

TW

48MT-40

48DE-302

48TW

46E-33

48

ME-20

52Y-20E

48TW-100

93235

95MT-100

95DE-305

92TW-100

95

Sulfur-M

odied

Grades

Slow


SC-102

45

GW

45510

45DCR-45

45SC-202

45GW

43GRT

45611

45PS-40

50SC-10

43GRT

47R-10

45PS-40A

42SC-132

43

SC-22

43

Medium


GNA

50712

43PM-40

50R-22

45711

45PM-40N

S50

GS

47

aXD,X

anthogen

disulde

modi ed

grades.



1.2.7 COMPOUNDING AND PROCESSING

Chloroprene rubber (CR) vulcanizates can be made using llers, plasticizers, anti-oxidants, and processing aids commonly used in diene rubber compounding.

Principles related to compounding and processing are discussed in subsequentsections.

1.2.7.1 Selection of Chloroprene Rubber Grades

To achieve the best compromises in compounds and vulcanizate properties, a properselection of grades is essential. Table 1.6 shows the best selection of elastomer toachieve desired processing properties. Table 1.7 illustrates a number of propertiesand the corresponding best choice of grade of elastomer for various vulcanizateproperties.

1.2.7.2 Blends with Other Elastomers

Blends of CR and other elastomers are desirable in order to achieve special proper-ties either of a CR-based compound or of a compound mainly based on the second

TABLE 1.6Selection of Compound Properties versus CR Grades

Desired Property Grades

Optimum processing Grades of low viscosity, precrosslinked grades

Best mastication S-gradesBest tackiness S-grades; grades of low crystallization tendencyBest green strength Medium fast crystallizing grades, high viscous grades

Highly extended compounds Grades of high viscosity; XD-gradesBest extrudability Precrosslinked grades

TABLE 1.7Selection of Vulcanizate Properties versus CR Grades

Desired Property Grades

Best tensile and tear resistance M-grades; XD-gradesBest compression set M-grades

Optimum heat resistance M-grades; XO-gradesBest low-temperature properties M-grades; XD-grades. Both of slow crystallizationLowest dynamic loss factor, highest elasticity S-grades

Best dynamic behavior S-grades; XD-gradesBest adhesion to textile and metal S-grades



component. In many cases general purpose diene rubbers, such as SBR, BR, or NR,are also used to reduce compound costs.

It is advantageous to select compatible polymers as blending components toform alloys during the mixing process. With respect to CR crosslinking systems thatare of dissimilar reactivity to that used in the blending elastomers, it is unsuitable inmost cases, thus resulting in an inhomogeneous network. Accelerator systems basedon thiurams and amines are best for an effective co-cure.

In the assessment of polymer blends, a somewhat lower level of physical pro-perties than a similar formulation based on pure polymers has to be taken intoaccount. In any case blending requires a well-adjusted mixing procedure.

A number of blends are used in the rubber industry, the most important of whichare summarized as follows:

1. Natural Rubber (NR) improves building tack, low-temperature exibility,elasticity, and reduces cost.

2. Butadiene Rubber (BR) added at levels of up to 10% to improve processing ofS-grades (reduced mill sticking); however, a reduction in ex-fatigue life maybe observed. BR also improves low-temperature brittleness.

3. Styrene-Butadiene-Rubber (SBR) has a predominant benet of reducingcost. It reduces crystallization hardening as well.

4. Acrylonitrile-Butadiene Rubber (NBR) is used for improved oil resistanceand (less importantly) for better energy-uptake in a microwave cure.

5. Ethylene-Propylene-Rubber (EPDM) with CR can be used in EPDM-vulcanizates to achieve a certain degree of oil resistance. It improvesadhesion of EPDM to reinforcing substrates. In blends where CR is dom-inant, price reduction and better ozone-resistance are obtained by EPDM.

Further details are given elsewhere in the literature.

1.2.7.3 Accelerators

CR can be crosslinked by metal oxides alone. Thus, there is a major differencebetween general purpose diene rubbers and CR. Suitable accelerators help to achievea sufcient state of crosslinking under the desired conditions.

Zinc oxide (ZnO) and magnesium oxide (MgO) are the most frequently usedmetal oxides; lead oxides are used instead for optimal water=acid=alkaline resistance.

Figure 1.7 refers to some curing characteristics and physical properties attainableby varying the amounts of ZnO and MgO.

In the absence of zinc oxides the rheometer curve is rather at. Although the stateof cure is increased, the crosslinking density remains low if zinc oxide is used alone.Best results are obtained with a combination of zinc oxide and magnesium oxide.

There is a tendency to marching modulus characteristics if high levels of bothmetal oxides are used.

The combination of 5 pphr ZnO and 4 pphr MgO is particularly favorable.In principle, the conditions described for M-grades are also valid for XD-grades.



S-grades are highly reactive with metal oxides so that no further acceleratorsare necessary to obtain a sufcient state of cure (although they are often used toadjust curing characteristics or to enhance the level of physical properties).

Various types of lead oxides are used in large amounts especially if resistanceagainst water, acids, and alkaline solutions is required. With lead oxides, scorchtimes can be reduced; therefore, particular caution is required in formulation,mixing, and processing. Lead oxides, on the other hand, enable self curing CRcompounds. A dispersed form should be used for health reasons.

With respect to the crosslinking mechanism reference must be made to thework of R. Pariser [14], who recommends sequences of chemical reactions, whichare basically inuenced by

1. Amount (approximately 1.5 mol%) and statistical distribution of allylicchlorine atoms in the main chain

2. Presence of ZnO=MgO3. Certain organic accelerators to form monosuldic bridges

(c) Effect of tensile (MPa) of the vulcanizates(d) Effect of on compression set (70 h/100 D.C:) (%)

(b) Effect on rheometer cure time t80 (min)(a) Effect on rheometer incubation time t10 (min)

0

5

10

5

10

5

10

5

106

2.4

2.83.0

2.6

2.6

3.0 2520

20

15

15

1010

1020

30

30

40

4050

606

8

4

10

4

(a) Magnesium oxide (phr)

Zinc

oxi

de (p

hr)

(b)

(d)(c) 8

0 4 8 0 4 8

0 4 8

FIGURE 1.7 Effect of zinc oxide and magnesium oxide levels on compound and vulcanizateproperties of CR. (Notes: (a) All vulcanizates were cured 30 min at 1508C. (b) Formulation:CR (medium fast crystallization grade) 100, stearic acid 0.5, PBNA 2, SRF N762 30, ETU 0.5.(c) Excerpt from technical information bulletin Baypren 2.2.1, Bayer AG.)



S-grades and, to a lesser extent, XD-grades contain inherent structures, whichare able to play the role of the organic accelerator in Parisers mechanism [15] andlead to measurable crosslinking density without further components.

As an organic accelerator, ethylene thiourea (ETU), which is preferably used innon-dusty forms, is widely used. Different derivatives of thiourea, such as diethylthiourea (DETU) and diphenyl thiourea (DPTU), are typical ultrafast accelerators,especially suitable for continuous cure.

In 1969, it was disclosed that under certain conditions ETU can cause cancer andbirth defects in some laboratory animals. As a result, a number of substitutes havebeen developed of which N-methyl-thiazolidine-2-thione (MTT: Vulkacit CRV=LG)[16] has gained technical importance.

Systems free of thioureas, or their substitutes, exhibit slower cure and givevulcanizates with higher set properties and lower heat resistance.

Best tear resistance is achieved by a combination of sulfur, thiurams, guanidine-based accelerators, and methyl mercapto benzimidazole (so-called MMBI system).

Levels of 0.51.0 pphr methyl mercapto benzimidazole have been shown toimprove resistance to ex cracking of CR vulcanizates, but tend to be scorchy. Thezinc salt of MMBI (ZMMBI, Vulkanox ZMB-2) is more effective in this respect.

A summary of important accelerator systems for CR M or XD-grades is com-piled in Table 1.8. A wide variety of other accelerators have been used with CR, butmost have not achieved widespread acceptance.

For the sake of completeness it should be noted that peroxide crosslinkinginstead of metal oxide crosslinking is also possible. However, the properties of thevulcanizates are inferior (e.g., heat resistance) to those achieved with a metaloxide=ETU system. Therefore, application remains limited.

1.2.7.4 Antioxidants, Antiozonants

Vulcanizates of CR need to be protected by antioxidants against thermal aging andby antiozonants to improve ozone resistance. Some of these ingredients also improveex-fatigue resistance.

Slightly staining antioxidants, which are derivatives of diphenylamine, such asoctylated diphenylamine (ODPA), styrenated diphenylamine (SDPA), or 4,4-bis(dimethylbenzyl)-diphenylamine are especially effective in CR compounds.

Trimethyl dihydroquinoline (TMQ) is not recommended because of its pro-nounced accelerator effect, which causes scorchiness.

MMBI is used to improve ex cracking resistance, but it tends to reduce thescorch time of compounds. Pronounced synergistic effects with ODPA or similarchemicals in order to optimize hot air aging have not been observed, so that it is notadvisable to use this chemical where optimal heat resistance is required.

A strong dependence of antioxidant on dosage of diphenylamine antioxi-dants was found, revealing that a level of 24 pphr is sufcient for most appli-cations (Figure 1.8). Similar relationships have been described by Brown andThompson [17].

In accordance with general experience, nonstaining antioxidants from the classof stearically hindered phenols or bisphenols are less effective.



p-Phenylenediamines are used as staining antioxidants=antiozonants and alsoimprove fatigue resistance, for which the DPTD type gives the most favorableresults. Other than DPTD, p-phenylenediamines tend to impair storage stabilityand processing safety.

A comparison of the different types of antioxidants is presented in Figures 1.9and 1.10.

Figure 1.9 representing the class of nonstaining antiozonants, which is describedas cyclic enole derivatives, are compared with the p-phenylenediamines to theirinuence on storage stability. Together with a second grade, described as phenolether, this class of rubber chemicals serves to give sufcient ozone protection understatic and, to a limited extent, dynamic conditions.

A study of the inuence of various p-phenylenediamines on ex crackingresistance is shown in Figure 1.10.

TABLE 1.8Typical Accelerator Systems for CR M and XD-Grades

System Dosage (phr) Characteristics

I ZnO=MgO 54ETUa 0.51.5 Good heat resistanceMBTS or TMTD 01 Good compression set

II MTT 0.51.5 Similar to Ib

III S 0.51 Slow curing, inferior heatresistance to I and IITMTM or TMTD 0.51.5

DPG or DOTG 0.51.5

IV S 0.51 Medium fast curing,optimum tear resistanceTMTM or TMTD 0.51.5

DPG or DOTG 0.51.5

MMBIc 0.51.5

V ETU 1.52.5 Ultrafast curing system,suitable for continuous vulcanizationDETU or DPTU 0.51.5

ZDEC 0.51.5

VI S 0.11.5 For food contactd

TMTM or TMTD 0.51.5

OTBGd 0.51.5

VII Lead oxide (instead of ZnO=MgO) 20 self curing-compounds

S 01Aldehyd-Aminee 1.52.5DPTU 1.52.5

a For industrial hygiene reasons, polymer-bound ETU is recommended.b Nontoxic alternative to ETU (N-methyl thiazolidine thione-2)Vulkacit CRV.c or similarly MBI.d BGA only. The actual status of legislation in different countries must be considered.e For example, butyraldehyde-amine reaction product (Vulkacit 576, suppl. Bayer AG).



It must be added that ozone protection is improved if antiozonants are usedtogether with microcrystalline waxes. Optimized CR vulcanizates have been shownto resist outdoor conditions for several years. Long-term tests with several antio-zonant=wax combinations in an outdoor test yielded the results presented inFigure 1.11.

1.2.7.5 Fillers

Generally, CR can be treated as a diene rubber as far as llers are concerned. Carbonblack and mineral llers, of either synthetic or natural origin, can be employed.

Active llers serve to improve physical properties, whereas less active orpredominantly inactive llers are used to reduce compound cost.

Figure 1.12 illustrates the typical inuence of carbon black types and levels inCR. Carbon black is easily incorporated in CR compounds. In most cases N 550,(FEF)-blacks or even less active types are sufcient to meet most requirements.

Aging conditions: 42 d/100C (cell oven)RemarkTest compound: CR (slow crystallizing grade) 100,stearic acid 0.5, magnesium oxide 4, polyethylene wax 3,black N 772 50, micro cryst.wax. 2, zinc oxide 5,ETU (80% batch) 0.8, TMTD 0.3

0 1 2

phr (Antioxidant)

H (S

h ore

A)E

B (%

)

3 4 5

0

50

100

0

+20

+10

FIGURE 1.8 Effect of antioxidant levels on aged properties of a CR compound.



0IPPD 2

2 2 2

6 PPDDTPD

Viscosity measurement after storage of the unvulcanized compound at 40C

NS

50

100

150

200

ML

1+4/

100

C7 d/40C14 d/40C

0 d/40C

FIGURE 1.9 The inuence of antioxidant=antiozonants on storage stability of CR com-pounds. (Note: NS refers to nonstaining antiozonant; described as cyclic acetal, VulkazonAFS=LG, Bayer AG.)

Kc

500No aging7 d/100CHot air aging400

300

200

100

0I PPD 2

2 2

6 PPDDTPD

Test procedure: De Mattia crack formation, DIN 53522(ISO 132)

FIGURE 1.10 PPDA Type antioxidant inuence of ex fatigue resistance of CR vulcanizates.



If active carbon blacks are necessary, dispersion problems may arise, but often thesecan be rectied by proper mixing techniques.

Active silica (BET-surface of approximately 170 m2=g) improves tear resistanceand also gives rise to better fatigue resistance. Microtalc may be used if optimumheat resistance or resistance against mineral acids or water is required. Silanecoupling agents are often used in conjunction with silica, silicate, and clay llersto improve these properties. In this case mercapto silanes or chloro silanes arepreferred.

Clays, talcs, and whitings are often used for cost reduction, either alone or incombination with reinforcing llers.

Although CR is inherently ame retardant, for certain applications it is neces-sary to further improve this property. This can be achieved with aluminum trihydrate,zinc borate, and antimony trioxide. A chlorinated parafn instead of a mineral oilplasticizer is also benecial.

1.2.7.6 Plasticizers

Mineral oils, organic plasticizers, and special synthetic plasticizers can be used intypical CR compounds in varying amounts between 5 to approximately 50 pphr.

These plasticizers can have the following effects:

Exposure of CR-samples under tension in an open-airtest (Engerfeld, Germany)The figures indicate cracks observed after time of exposure

I PPD 1

0

20

*No cracks after 7 years

Year

s

Elongation

Mon

ths

60%

8

7

6

5

4

3

2

1

0

30%20%40

60

80

1 1 1 2 2 2 2 2 2 2 2

6 PPD

waxNS

*

FIGURE 1.11 Inuence of antiozonants on weather resistance of CR. (Note: NS here refers toEnol-ether type nonstaining antiozonant, Vulkazon AFD, Bayer AG.)



1. Lowering of the glass transition temperature2. Reduction in tendency to crystallize3. Lowering of compound cost

A summary of typical plasticizers and their effects is given in Table 1.9.Special plasticizers are very effective in lowering the glass transition temperature

and improving rebound resilience. These products are needed for articles in whichresilience is required down to approximately 458C.

Unfortunately, such plasticizers also promote the crystallization rate, so thatpolymers with low crystallization tendency have to be chosen.

Highly aromatic mineral oils can be recommended for compounds where areduction in crystallization rate is required. This class of plasticizers is also compati-ble, so that 50 pphr or even more can be used without exudation effects. Amongother mineral oil plasticizers, napthenic oils have gained importance where stainingdue to leaching and migration must be avoided. Their compatibility is somewhatlimited depending on the compound formulation. Check with local health regulationson the use of highly aromatic oils as some are suspected carcinogens. Parafnic oilsare of very limited compatibility, so that they nd only restricted application. Theseare the most economical plasticizers to use.

Black (phr)

Har

dnes

s (sh

ore A

)

040

50

60

70

80

90

10 20 30 40 50 60 70 80

N 110N 220N 330N 550N 774N 990

FIGURE 1.12 Relationship of carbon black loading on hardness of CR compounds. (Note:Medium fast crystallizing grade CR with 10 pphr aromatic oil (Technical Information BulletinBaypren 2.3).)



At higher cost, synthetic plasticizers such as dioctyl phthalate (DOP), butyloleate (Plasthall 503), or phenol alkyl-sulfonic acid esters can be used if aromaticmineral oils are not possible. These offer improved low-temperature exibility andare nondiscoloring and nonstaining.

If higher heat resistance is needed, polymeric, chlorinated parafns, polyesters,and low volatility mineral oils are used.

Good ame resistance is obtainable with liquid CR, chlorinated parafns, andphosphate esters.

1.2.7.7 Miscellaneous Compounding Ingredients

This section gives a brief description of other common compounding ingredientssuch as stearic acid and derivatives, resins, processing aids, and blowing agents.

Stearic acid at levels of 0.51.0 pphr is recommended in CR compounds toimprove processing and to reduce mill sticking. Zinc stearate acts as an accelerator;

TABLE 1.9Inuence of Plasticizers on Low-Temperature Behavior of CR

Effect on Low Temperature

MaxDosage(phr)

GlassTransition

TemperatureBrittlenessTemperature

CrystallizationReduction

CompoundPrice

Mineral oils

Aromatic

therefore, one must take care to avoid higher temperatures during mixing andprocessing where it may be formed through the reaction of zinc oxide and stearicacid.

Resins such as cournarone resins are able to act as dispersants and tackiers.Sometimes, reactive reinforcing phenolic resins are also used, in which case ifthe crosslinking component (e.g., hexamethylene tetramine or other formalde-hyde donors) is used, it must be added in the second stage together with theaccelerators.

For some applications CR compounds must be adhered to textiles or metals.Bonding resins of the resorcinol type are normally used as internal bonding agents.Because of the scorching effect of resorcinol, modied grades, such as resorcinoldiacetate, are recommended to preserve processing safety.

There are no objections to the use of certain processing aids, of which there aremany on the market. For applications and handling, the suppliers recommendationsmust be followed. In addition to stearic acid and commercial process aids, low-molecular weight polyethylene, waxes, and wax-like materials, and blends with otherelastomers (e.g., BR) are commonly employed.

Vulcanized vegetable oils are used for soft compounds since they permit the useof high plasticizer levels while maintaining good green strength with calendering andextrusion properties. There are specially developed products on the market, such asFaktogel Asolvan, which do not cause a drop in swelling resistance.

Blowing agents commonly used in other diene rubbers are also suitable for CR,for example, azodicarbonamide and sulfohydrazide types.

1.2.8 PROCESSING

Chloroprene rubber is typically supplied in chip form and is normally coated withtalc to prevent blocking during shipping and storage. These chips can be processedon open mills or internal mixers using conventional or upside-down techniques.Crystallized chips cause no problems in processing because the crystallites melt attemperatures above 408C608C.

It is recommended that magnesium oxide be added in the early stage of themixing cycle and not to exceed dump temperatures of 1308C to prevent undesirableside reactions (cyclization, scorch).

Processing safety requires the incorporation of all ingredients with crosslinkingactivity, for example, zinc oxide, lead oxide, accelerators, and others, in the laterstages of mixing, if the compound temperature is not too high, or in the second stage(productive mix).

For high-quality, lightly loaded compounds, a two-stage mixing is recommendedwith a 1 day rest period between the stages.

CR compounds, especially of low viscosity, mineral lled, or those based onS-types, show a tendency to mill sticking. To overcome this effect, low friction ratiosand low-temperature processing are recommended. Process aids may also assistin providing better mill release. If the compound temperature exceeds 708C, CRcompounds become somewhat grainy in appearance, lose cohesive strength, andstick to metal surfaces.



S-grades breakdown in viscosity under shear, which is benecial for tackiness,and is important for articles such as belts and some hoses. Another consequence of thisphenomenon is that S-grades are the preferred basic material for low-viscosity frictionand skim-compounds.

CRmay also be used in dough processes employed in coated fabrics for variousapplications. It is important to ensure that regulations related to solvent vapors arefollowed for those processes where combinations of solvents such as naphtha=methylethyl ketone (MEK) or naphtha=toluene are employed. The solutions may containspecial bonding agents, for example, polyisocyanates. Pot lifetimes of such com-pounds are fairly short (14 h), because of the crosslinking activity of such materials.

CR compounds can be used in all vulcanization processes, such as compres-sion and injection molding, hot air, steam autoclaves, and continuous vulcanization(salt baths, microwave-hot air cure, CV-cure).

Reversion is not a problem for CR, so curing temperatures of up to 2408C arepossible.

1.2.9 PROPERTIES AND APPLICATIONS

1.2.9.1 General

The attraction of CR lies in its combination of technical properties, which aredifcult to match with other types of rubber for a comparable price. With the correctcompound formulation, CR vulcanizates are capable of yielding a broad range ofexcellent properties as shown below:

1. Good mechanical properties, independent of the use of reinforcing agents2. Good ozone, sunlight, and weather resistance3. Good resistance to chemicals4. High dynamic load-bearing capacity5. Good aging resistance6. Favorable ame resistance7. Good resistance to fungi and bacteria8. Good low-temperature resistance9. Low gas permeability10. Medium oil and fuel resistance11. Adequate electrical properties for a number of applications12. Vulcanizable over a wide temperature range with different accelerator

systems13. Good adhesion to reinforcing and rigid substrates, such as textiles and metals

1.2.9.2 Physical Properties

Polychloroprene vulcanizates possess good physical strength, and with optimumformulations, the level is comparable to that of NR, SBR, or NBR.

Tear resistance of CR vulcanizates is better than that of SBR. Tear propagationresistance of CR vulcanizates containing active silica may be greater than that ofthose with natural rubber. CR vulcanizates show good elasticity, although they do



not reach the level of NR. Table 1.10 provides a comparison of CR with NBR, NR,and SBR.

The compression set of CR is low over a wide range of temperatures from108C to 1458C, as given in Figure 1.13. The low-temperature compression setis one of the key values employed for the assessment of vulcanizates used in seals.For CR, testing is commonly run at 108C, the temperature at which optimumcrystallization occurs. It is possible to improve the low-temperature compression setto less than 50% at 308C by using the most crystallization resistant CR andlow-temperature plasticizers.

At higher temperatures, where aging also plays a role, the compression set curvesare at a lower level than for a large number of other elastomers. It is important touse M-types of CR, heat-resistant antioxidants, and nonvolatile plasticizers.

The abrasion resistance of CR is comparable to that of NBR.The gas permeability is roughly equivalent to NBR of medium ACN content.

Thermal conductivity and thermal expansion are comparable to other elastomers.

1.2.9.3 Aging and Heat Resistance

CR M-type vulcanizates, especially those that contain optimized antioxidants andcrosslinking systems and low volatility plasticizers, display good heat resistance.

TABLE 1.10Comparison of Typical Vulcanizate Properties of CR, NBR, NR, and SBR

Basic PropertiesChloroprene

RubberNitrileRubber

NaturalRubber

Butadiene-StyreneRubber

Tensile strength (MPa) Up to 25 Up to 25 Up to 28 Up to 25Hardness (Shore A) 3090 From 20 to

ebonitehardness

From 20 to

ebonitehardness

From 20 to

ebonitehardness

Abrasion resistance A A BC B

Tear propagation resistance B C A CFatigue resistance A A A ARebound B BD A BHot air resistance, temperature

limit for continuous stressing(8C) (VDE 0304, Part 2)

80 80 60 70

Low-temperature exibility BC BD B BC

Weathering and ozone resistance B D D CFlame retardance AB EC EC ECCompression set (22 h at 708C) B B C B

Oil resistance B A D D

Note: AExcellent; BVeryGood; CGood; DFair; EUnsatisfactory. The ratings are compoundcomposition dependent, hence all optimum values may not be obtained simultaneously.



They neither soften nor harden over a long period of stress; remaining serviceableand elastic.

In the ASTM D 2000 and SAE J 200 systems, CR is positioned with respect tothermal aging between NR and CSM.

A more relevant description of heat resistance is shown in Figure 1.14, where theArrhenius equation is applied to the thermal aging of optimized CR vulcanizates.

The continuous service temperature in accordance with VDE 0304, Part 2(25,000 h), is 808C. Optimized vulcanizates for automotive application can performfor 1000 h at 1008C1108C and will survive short- or medium-term exposure upto 1208C.

1.2.9.4 Low-Temperature Flexibility

Apart from crystallization effects, the differential scanning calorimeter reveals aglass transition temperature for polychloroprene at around 408C, which is practi-cally independent of the type of polymer tested. Compounding ingredients can shiftthe glass transition temperature further to lower temperatures. Typical data aresummarized in Table 1.11. Low crystallization grades of CR need to be used.

600

10

20

30

40

50

60

70

80

90

100

40 20 0 20 40 60Temperature (C)

CR gradeLower

Slow crystallizing 10+10+29 +146

+145+145

Medium fast crystallizingFast crystallizing

UpperTemperature limit (C) for C.S.

Synthetic low-temperature plasticizers allows CR vulcanizates to exhibit elasticbehavior down to temperatures of around 458C to 508C (depending on theformulation).

1.2.9.5 Flame Retardance

CR vulcanizates are inherently ame resistant. The good ame resistance propertiesof the polymer itself mean that stringent end-user specications can be fullled bythe use of appropriate compounding materials such as chlorinated parafns insteadof mineral oils, mineral llers plus aluminum trihydrate, zinc borate, and antimonytrioxide.

180102

103

104

105

160 140 120Temperature (C)

Parameter: Aging time to 100% elongationCR- M-grade, cable sheathing compound

Tim

e (h)

100 80 60

FIGURE 1.14 Arrhenius plot of air aged CR vulcanizates (VDE 0304=Part 2=7.59).

TABLE 1.11Typical Low-Temperature Properties of CR

Polychloroprene

Glass transition temperature (DSC Test, 2nd heating cycle) 408CVulcanizate properties 6575 Shore A Without plasticizer With plasticizer

Torsion pendulum test DIN 53445 (8C) 308 438Brittleness point ASTM D 736 (8C) 368 528



Limited oxygen index values of 50% can be attained with CR and constructionmaterials can be manufactured to meet, for example, DIN 4102, Part I, Class B1.

However, like all organic substances, CR vulcanizates will decompose at hightemperatures such as those encountered in open res. In addition to decompositionproducts such as carbon dioxide and water, corrosive hydrogen chloride gas is alsoformed.

1.2.9.6 Resistance to Various Fluids

CR possesses medium oil resistance making the polymer suitable for articles resist-ant to intermittent oil exposure or exposure to less aggressive oils such as parafnicand napthenic oils or corresponding hydraulic oils. The resistance to regular fuels islimited, and insufcient in fuels with high aromatic content.

Additives in oils may cause hardening of vulcanizates. CR, however, proves tobe more stable than a typical NBR vulcanizate.

Unless a lead oxide cure is used, CR compounds can fail to meet severe waterresistance requirements. The use of a lead oxide cure allows limited swell in water,so that volume changes of only a few percent can be obtained. Properly compoundedCR also exhibits good resistance to dilute acids and alkaline solutions at moderatetemperatures.

A list of the swell resistance in various chemicals is given in Table 1.12.

1.2.9.7 Resistance to Fungi and Bacteria

Rubber articles in contact with soil for longer periods of time are liable to attackby soil bacteria and fungi. This can lead to underground cables being destroyed.In contrast to the majority of other rubber types, CR shows a surprisingly higherlevel of resistance to these microorganisms. This resistance can be further enhancedby the use of fungicides such as Vancide 51Z and a fungus-resistant plasticizerpolyether-[di (butoxy-ethoxy-ethyl) formal].

1.2.10 APPLICATIONS

CR is one of the dominant specialty elastomers and is the basis for a wide variety oftechnical rubber goods. The estimated consumption of CR solid rubber, CR adhesiveraw materials, and CR latex is approximately 300,000 tons per year (excludingformer Soviet Union and PR of China). Approximately two-thirds of this consump-tion is for typical rubber applications. Thus, the CR Market can be analyzed in termsof the market sector as shown in Figure 1.15.

Alternatively, the CR market can be analyzed as shown in Figure 1.16 in termsof the article type.

Examples for some applications are summarized subsequently.

1.2.10.1 Hoses

CR is the classical elastomer for hose covers. Industrial hydraulic hoses, eithermedium- or high-pressure types, currently contain CR covers. For cost reasons,



TABLE 1.12Comparing the Swell of CR, NBR, SBR, and NR in Various Fluids

Chemicals Swelling Conditions CR NBRa SBR NR

Acetic acid, 10% 508C, 12 weeks E E E EAcetone 208C, 20 d CD E CD DAcetone 308C, 20 d D E D DASTM fuel No. 3 508C, 28 d E E E E

ASTM oil No. 1 708C, 28 d BC A DE EASTM oil No. 1 1008C, 28 d BC A DC EASTM oil No. 2 708C, 28 d CD A E E

ASTM oil No. 2 1008C, 28 d CD A E EASTM oil No. 3 708C, 28 d E C E EASTM oil No. 3 1008C, 28 d E C E E

Ethylene glycol 1008C, 20 d A A A ABFatty acidb BC A D DR 11 208C, 28 d E E E E

R 12 208C, 21 d CD CD D EGlycerol 508C, 20 d A A A ABGlycerol 1008C, 20 d B B B EMethanol 508C, 20 d C CD B B

Methyl ethyl ketone 208C, 28 d E E DE DEParafnb B A DE DESulfuric acid, 25% 508C, 12 weeks BC B C C

Sulfuric acid, 50% 1008C, 12 weeks E E E EToluene 208C, 28 d E E ECity gasb AB A CD CD

Water, distilled 208C, 2=4 years B=C B=B B=B C=C

a Perbunan N 3310 Bayer AG.b Data from Dichtelemente, Vol. II (1965), Asbest-u. Gummiwerk, Martin Merkel KG, Hamburg.

Notes: Ratings: A, extremely resistant; B, highly resistant; C, resistant; D, partially resistant; E, not resistant.

Mechanical goods 34%

Auto 30%

Wire and cable 14%

Building 10%

Others 10%

Footwear 2%

FIGURE 1.15 Polychloroprene end use application survey.



blending with SBR is practiced. CR covers are also used where hoses resistant to oiland ozone are required. A typical hose cover formulation is given in Table 1.13.Baypren 210 is a medium crystallization general purpose grade of CR and if betterlow-temperature resistance is needed, Baypren 110 is suggested.

Hoses 28.2%Conveyer belts 2.7%

Profile 7.0%

Transmission belts 7.9%

Cables 14.2% Molded goods 25%

Others 14.3%

FIGURE 1.16 Polychloroprene application survey.

TABLE 1.13Baypren Hose Cover

Baypren 210 100Maglite D 4

Stearic acid 1Vulkanox OCD 3Vulkanox 3100 1.5Antilux 111 2

N-660 Black 100Aromatic oil 20Mesamoll 20

Aux 42 3Zinc oxide 5Vulkacit thiuram MS (TMTM) 0.8

Vulkacit D (DOTG) 0.8Sulfur 1

Total 262.1

Compound properties

ML 1 4 at 1008C 37t5 at 1208C (min) >45

Vulkameter data at 1608C

FmaxFmin (N m) 38.1t10 (minutes) 3.2

t80 (minutes) 16.6t90 (minutes) 21.5

(continued )



Other applications of importance are suction and discharge hose covers andtubes and general tubing for the automotive industry.

1.2.10.2 Molded Goods

Bellows and seals for various applications, of which axle boots are a typical example,are made from CR. A suggested compound is illustrated in Table 1.14. Thecompound is designed to have excellent low temperature, ex, ozone, and weatherresistance.

TABLE 1.13 (Continued)Baypren Hose Cover

Physical properties, cured 30 min at 1608C

Hardness (Shore A) 74Tensile (MPa) 14.0Elongation (%) 215

Compression set B (ASTM D395B)

70 h at 1008C (%) 3170 h at 1258C (%) 53

Aged in air 7 days at 1008C-change

Hardness, pts. 10Tensile (%) 10Elongation (%) 28Brittle pointBP (8C) 36

TABLE 1.14Baypren Automotive Axle Boot

Baypren 126 100.0Maglite DE 4.0

Stearic acid 0.5Vulkanox OCD 2.0Vulkanox 4020 2.0

Antilux 110 2.5FEF (N550) black 35.0SRF-HM (N774) black 40.0

DOS 25.0ZnO 5.0Rhenogran ETU 80 0.8

Vulkacit Thiuram=C 0.8

Total 217.6Density (g=cm3) 1.35



CR has been used for many years as the elastomer of choice for bearings inmachinery and bridges.

No problems occur with CR rubber-to-metal bonding using conventionaltechniques of metal preparation and a commercial adhesive such as Chemlok 855or 8560 single coat system or a two coat combination of Chemlok 205=220 or805=8200.

TABLE 1.14 (Continued)Baypren Automotive Axle Boot

Compound properties

ML 1 4 at 1008C 50ML min at 1458C 38t5 at 1208C (minutes) 24

t5 at 1458C (minutes) 5


Mmin (N m) 1.9Mmax Fmin (N m) 38Ts 10 (minutes) 1.8Tc 80 (minutes) 8.5Tc 90 (minutes) 13

Vulcanizate properties cured 13 min at 1708C

Hardness, Shore A 66100% Modulus (MPa) 4.6200% Modulus (MPa) 11.8Tensile strength (Mpa) 17.2

Elongation (%) 285Tear die C (kN=mm) 35

Aged in AIR 7 days at 1008C-changea

Hardness (pts) 7100% Modulus (%) 45Tensile (%) 1Elongation (%) 11Tear die C (%) 7DeMattia Flex (DIN 53522)b cured tc 90 2 minUnaged100% Modulus (MPa) 4.9

Kilocycles 500Aged in air 7 days at 1008C

100% Modulus (MPa) 6.9Kilocycles 1000

a Average of samples cured t90 and t90 2 min.b Kc to crack rating 6 (crack size >3 mm).



1.2.10.3 Belting

CR is the dominant elastomer for power transmission and timing belting. Other usesinclude various industrial belts. A starting compound is given in Table 1.15. Thecompound is designed for excellent ex resistance. The polyester ber is used forgood dynamic compression resistance.

Mining conveyor belts are based on CR where stringent ame retardancerequirements must be fullled. Flame retardant mineral llers used in combinationwith a chlorinated wax are recommended along with a silica ller for abrasion andtear resistance.

1.2.10.4 Extruded Proles

Automotive and building proles in the hardness range of 50 Shore A to 90 Shore Aand sponge proles have been in use for many years. In the construction industry,some CR has been replaced by EPDM for cost reasons; however, CR is stillthe preferred polymer if ame retardance and some oil resistance are required.An extruded road seal formulation is provided in Table 1.16. Baypren 115 maybe used in place of Baypren 111 if improved extrusion properties are wanted.Desical 85 is used to absorb moisture in the compound to prevent porosity in theextrudate.

1.2.10.5 Wire and Cable

CR is the polymer of choice for cable jackets in heavy duty applications (transport,mining, welding, and others). Typical general purpose cable jackets are shown inTable 1.17.

TABLE 1.15Core Compound for Cut Edge V-Belts (ID 0044.CR)

Baypren 711 100.00

TAKTENE 1203 5.00Magnesium oxide 4.00Stearic acid 3.00

Vulkanox OCD 2.00Vulkanox 3100 1.50Silica 10.00

N-660 Black 30.00Sundex 8125 5.00Polyester ber (1 mm) 15.00Zinc oxide 5.00

Rhenogran ETU-75 0.25

Sulfur grade is used in this application for good dynamic properties.



TABLE 1.16Baypren Road Seal Formulation

Baypren 111 100.0

Maglite D 4.0Vulkanox OCD=SG 1.5Vulkanox 3100 1.5

N-660 Black 35.0TP-90B 7.5Sundex 790 7.5

Sunolite 666 2.0TMTM 0.5DOTG 0.5

Sulfur 0.5Zinc oxide 5.0Rhenogran ETU-75 1.5Desical 85 3.0

Total 170.0

Physical propertiescured 20 min at 1538C

Hardness (Shore A) 60Tensile (MPa) 14.7

Elongation (%) 315

Aged in air oven 70 h at 1008C-change

Hardness (pts) 9Tensile (%) 1.9Elongation (%) 1.6Aged in ASTM #3 Oil 70 h at 1008C-change

Weight (%) 37.2

TABLE 1.17Baypren Cable Jacket Formulations

Baypren 211 100.0

Baypren 226 100.0Maglite D 4.0 4.0Stearic acid 1.0 1.0

Vulkanox DDA 2.0 2.0Suprex clay 120.0 150.0N-774 Black 2.0 2.0

Aromatic oil 20.0 30.0Parafn 5.0 5.0Zinc oxide 5.0 5.0Rhenogran ETU-80 1.5 1.5

Vulkacit DM (MBTS) 0.5 0.5

Total 261.0 301.0

(continued )



1.2.10.6 Miscellaneous

Some other applications are rollers for the printing and textile industry,coated fabrics, membranes, air bags, tank linings, closed cell sponge surf, anddiving suits.

REFERENCES

1. J.A. Nieuwland, Acetylene Reactions, Mostly Catalytic, paper presented at FirstNational Symposium on Organic Chemistry, ACS Dec. 2931, 1925. Rochester, NY.

2. A.M. Collins, The Discovery of Polychloroprene, Rubber Chem. & Technol., 46(2):48, JuneJuly, 1973.

3. P.S. Bauchwitz, J.B. Finlay, C.A. Stewart, Jr., Vinyl and Diene Monomers, Part II E.C.Leonhard, ed., John Wiley and Sons, NY, pp. 11491184, 1971.

4. P.R. Johnson, Polychloroprene Rubber, Rubber Chem. & Technol., 49(3): 650,JulAug, 1976.

5. W. Obrecht, Makromolekulare Stoffe Bd E 20 H. Bartl, J. Falke. (Methoden derorganischen Chemie, Thieme Verlag Stuttgart, NY, S. 843856, 1987 (in German).

6. W. Gobel, E. Rohde, E. Schwinum, KautschukGummi, Kunststoffe, 25: 11, 1982 (inGerman).

7. R. Musch, Polychloroprene Grades with Improved Processing Behavior and VulcanizateProperties (140). Rubber Division, ACS Meeting, Oct., 1991, Detroit.

8. R. Musch, U. Eisele, New Polychloroprene Grades with Optimized Structure PropertyRelationship. (136). Rubber Division, ACS Meeting, Oct., 1989, Detroit (KautschukGummi in press).

9. R. Petioud, Q. Tho Pham, I. Pol, Sci. Pol. Chem. Ed., 22: 13331342, 1985.10. R.R. Garett, C.A. Hargreaves, D.N. Robinson, I. Macromob. Sci. Chem., A 4.8: 1679, 1970.11. C.A. Aufdermarsh, R. Pariser, I. Pol. Sci. A. 2: 4727, 1964.

TABLE 1.17 (Continued)Baypren Cable Jacket Formulations

Compound properties

ML 1 4 at 1008C 28 39t5 at 1208C (minutes) 18 17


Mmin (N m) 0.7 0.8Mmax (N m) 26.0 30.0ts10 (minutes) 0.9 0.7tx80 (minutes) 3.4 3.8

Physical properties cured 90 s at 2008C in steam

Hardness (Shore A) 56 60100% Modulus (MPa) 2.5 2.6300% Modulus (MPa) 4.0 4.2Tensile (MPa) 12.6 12.7

Elongation (%) 760 710



12. E. Rohde, H. Bechen, M. Mezger, KautschukGummi, Kunststoffe, 42: 11211129,1989 (in German).

13. The Synthetic Rubber Manual, 15th Edition 2002 IISRP, Houston, Texas.14. R. Pariser, Kunststoffe, 50, Nr. 11: 623, 1960 (in German).15. R. Musch, U. Eisele, International Rubber Conference, 90, June 1214, 1990, Paris,

(KautschukGummi, Kunststoffe in press).16. U. Eholzer, Th. Kempermann, W. Warrach, Rubber & Plastics News Technical Note

Book, Nr. 48, May, 1985.17. D.C.H. Brown, J. Thompson, Rubber World, 32, Nov., 1981.



2 Acrylonitrile ButadieneRubber


CONTENTS

2.1 Introduction.................................................................................................... 392.2 Grades and Types of NBR............................................................................. 42

2.2.1 Standard NBR.................................................................................. 422.2.1.1 ACN Content .................................................................. 462.2.1.2 Mooney Viscosity........................................................... 472.2.1.3 Polymerization Temperature........................................... 472.2.1.4 Stabilizer ......................................................................... 482.2.1.5 Specic Gravity .............................................................. 48

2.2.2 Low Mold-Fouling NBR Grades..................................................... 482.2.3 Precrosslinked NBR Grades ............................................................ 482.2.4 Carboxylated NBR Polymers .......................................................... 502.2.5 Terpolymer of Acrylonitrile-Butadiene-Isoprene Elastomer ........... 512.2.6 Liquid NBR ..................................................................................... 522.2.7 NBR Carbon Black Masterbatches.................................................. 532.2.8 Plasticizer-Extended NBR ............................................................... 552.2.9 Nitrile PVC Blends .......................................................................... 552.2.10 Compound Design of Standard NBR.............................................. 58

2.2.10.1 Selection of the Correct NBR ........................................ 582.2.10.2 Fillers .............................................................................. 632.2.10.3 Plasticizers ...................................................................... 662.2.10.4 Curing of Standard NBR................................................ 722.2.10.5 Carboxylated Nitrile Rubbers ......................................... 82

2.2.11 NBR=PVC with and without Plasticizerand Plasticizer-Extended NBR ........................................................ 86

2.2.12 Processing ........................................................................................ 89References ............................................................................................................... 91

2.1 INTRODUCTION

Acrylonitrile butadiene rubber (NBR), also known as nitrile rubber or NBR, was rstdeveloped by Konrad, Tschunkur, and Kleiner at I.G. Farbenindustrie, Ludwigshafen,then with Oppau and Hoechst as a joint development in 1930, and commercialized in

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C002 Final Proof page 39 27.9.2007 10:07am Compositor Name: VAmoudavally

39

1934. The original name was Buna N and later changed to Perbunan. The SecondWorld War prevented export to Great Britain and the United States; hence StandardOil Company and other companies, licensees of I.G. Farbenindustrie, began produc-tion in 1941 by Goodyear, Firestone, U.S. Rubber, and B.F. Goodrich as part of thewar effort in the United States. In addition, Polymer Corporation in Sarnia, Ontario,Canada, began nitrile production in 1948.

A joint company of Distillers Company and B.F. Goodrich began production ofNBR in Barry, S. Wales in 1959. The production of nitrile rubber spread betweenthat time and 1962 to other countries of the world including France, Italy, and Japanas well as Russia. The total capacity worldwide in 1962 was estimated at 167,000metric tons, which has grown to approximately 480,000 metric tons in 2001 [1].A listing of the various suppliers of NBR worldwide is given in Table 2.1 as of 2005[2]. There has been considerable consolidation of producers and production facilitiesin recent years so this information may become outdated with time [3,4].

TABLE 2.1Worldwide NBR Suppliers

Company Symbol Trade Name Country

Dwory SA Dwory KER Poland, Oswiecim

Carom SA CO CAROM RomaniaEliokem Chemicals Eliokem Chemigum France, Le Havre

USA, AkronHyundai Petrochemical

Co. Ltd.

Hyundai SEETEC Korea, Daesan

Industrias Negromex SAde CV

N EMULPRENE Mexico

JSR Corporation JSR JSR Japan, YokkaichiKorea KumhoPetrochemical Co.

KKPC KOSYN Korea, Seoul

Lanxess Elastomers Lanxess LE Perbunan NT Krynac France, La WantzenauLanxess Inc. Lanxess LINC Krynac Perbunan NT Canada, SarniaLanzhou Chemical

Industry

LZCC NBR China

Nantes Industry Co. Ltd. Nantex NANTEX Taiwan, KaohsiungNegromex Industrias, SAde CV

Negromex N-xxxx Mexico

Nitriex Industriae Comercio SA

Nitriex NITRIFLEX N Brazil, Rio de Janeiro

ParaTec Elastomers LLC Paratec Paracril Paraclean Paracril

OZO

Mexico, Altamira

Petrobras Energia SA Petrobras ARNIPOL Argentina, Buenos AiresPetroChina Jilin

Petrochemical Co.

JIL NBR China, Jilin

Petroex Industriae Comercio SA

Petroex PETROFLEX Brazil

Robert C. Klingender/Handbook of Specialty Elastomers DK4127_C002 Final Proof page 40 27.9.2007 10:07am Compositor Name: VAmoudavally


The oil, fuel, and heat resistance of nitrile rubber, or NBR, havemade this elastomervery important to the automotive non-tire and industrial rubber business. NBR isconsidered to b

handbook of specialty elastomers - robert c_ klingender

Documents