8/2/2019 Thermoplastic Engineering (1)

1/19

1

1

Bhuwneesh

Thermoplastic MaterialsEngineering Plastics

8/2/2019 Thermoplastic Engineering (1)

2/19

2

Replace metallic parts

Strength and stiffness

Retention of properties over range of temperatures

Toughness to withstand incidental damage Dimensional stability

Low creep

Low CTE

Withstand environmental factors (UV, O2, chemicals)

Shaped easily

Engineering Thermoplastics

8/2/2019 Thermoplastic Engineering (1)

3/19

3

Compared to commodity plastics

More expensive

Better mechanical and tribological properties

Water absorption: As most Engineering Thermoplastics are formed viacondensation polymerization process.

Higher processing conditions, low recylability Expensive additives

Engineering Thermoplastics

8/2/2019 Thermoplastic Engineering (1)

4/19

4

Summary: Class Vs. Performance

Styrenic Vinyl Cellulosic

Olefins Acetates

Imides

Amides

Flouro Esters

Ether sulphones

Arsulphid

8/2/2019 Thermoplastic Engineering (1)

5/19

5

Polyamides or Nylons (PA)

8/2/2019 Thermoplastic Engineering (1)

6/19

6

( )nCN N C C C

O OH HH

H

H

H

[ ]a [ ]b

Polyamides or Nylons (PA)

8/2/2019 Thermoplastic Engineering (1)

7/19

7

Polarity

Crystallinity

Sharp meltpoint

Strength

Comparison of higher & lower nylon numbers

Class: Aliphatic, semi-aromatic and aromatic (increasing costand performance)

PA General Family Characteristics

8/2/2019 Thermoplastic Engineering (1)

8/19

8

Transparent (barely)

cook in bag (turkey)

Anti-frictionnot like PTFE but good

Toughnessexcellent

Fatigue resistanceexcellent

Water absorptiona weakness (.2-2.5%must be dried forinjection molding)

Highly crystalline (for better mechanicals and abrasionresistance)

PA General Family Characteristics

8/2/2019 Thermoplastic Engineering (1)

9/19

9

Nylon 6,6

C C C C C CNH2 NH2

H

H

H

H

H

H

H

H

H

H

H

H

Hexamethylenediamine(6 carbons)

8/2/2019 Thermoplastic Engineering (1)

10/19

10

Nylon 6

C C C C C CNH2

O

OH

H

H

H

H

H

H

H

H

H

H

AmineGroup

AcidGroup

8/2/2019 Thermoplastic Engineering (1)

11/19

11

Nylon 6

C

C

C

C

C

C

NH2

O

H

H

H

H

H

H

H

H

H

H

N

C

C

C

C

C

C

OH

O

H

H

H

H

H

H

H

H

H

H

H

O

H

H

Water

8/2/2019 Thermoplastic Engineering (1)

12/19

12

C C

C C

C

CC

C

O O

N C

C C

C

CC

N

H

H

H H

H H

H H

HH

Aramids

8/2/2019 Thermoplastic Engineering (1)

13/19

13

Nylon 6,6

General

Nylon 6 Copycat

Nylon 6,10 Less water absorption

Nylon 6,12 Flexibility and less water

Nylon 2,2 Strength

Nylon 6T Higher temperature

Properties of Specific Nylon Types

8/2/2019 Thermoplastic Engineering (1)

14/19

14

Injection molding Shrinkagecrystallinity.018 in/in Dry it first

Extrusion

Low melt viscosity Be careful of decomposition

Fibers Drawing Crystallization

Orientation

Processing Nylon

8/2/2019 Thermoplastic Engineering (1)

15/19

15

Nature of polymer bonding not understood

Bifunctional monomers

Polymers1000 units long Larger unitsmolecular still to eliminate water

Control of melting point and length Many combinations of polyesters Trying polyamides Settling on 6,6

Tremendous success Name

Delawear, Wacra, Norun, Nuron, Nulon, Nilon, Nylon

Nylon History

8/2/2019 Thermoplastic Engineering (1)

16/19

16

Thermoplastic Polyimides (PI and PAI)

8/2/2019 Thermoplastic Engineering (1)

17/19

17

Thermoplastic Polyimides (PI and PAI)

C

C

C

C

C

C

C

C

N

O

OH

H

H

()n

)n(

8/2/2019 Thermoplastic Engineering (1)

18/19

18

Very stiff

Highest thermal stability

PI cannot be melted or melt processed

PAI can be (Torlon)

PI is sintered (Vespel)

PI film is cast as monomers and heated to polymerize (Kapton)

Properties

8/2/2019 Thermoplastic Engineering (1)

19/19

19

PI is used in circuit boards

High temperature parts

Low friction bearings, sliding parts

Gears

Uses