nbr/sbr blends compatibilized with amphiphilic …€¦ · secondary pyrolysis stages at low...

ROHSTOFFE UND ANWENDUNGEN RAW MATERIALS AND APPLICATIONS

30 KGK · 07-8 2016 www.kgk-rubberpoint.de

Vulcanized rubber scraps · Organophilic montmorillonite · Pyrolysis · Carbon Nanotubes

Pyrolysis of rubber waste bearing a range of different compositions was ac-complished under catalytic conditions in a horizontal pyrolyzer and estimated to be promising from the economic point of view and convincingly effective to obtain carbon nanotubes (MWCNTs) in a reasonable yield. The rubber formu-lations are comprising NBR compatibi-lized with SBR with the aid of amphi-phobic organic-inorganic hybrids based on Na-montmorillonite and a surface active modifier, cetyltrimethylammoni-um bromide (CTAB), permanently linked to the montmorillonite. It was found, that there is a close relation between the perfection of the resulting carbon nanotubes (CNTs) as well as the yield and the conditions under which the im-miscible rubber components were origi-nally compatibilized.

Mit amphiphilen Montmorillonit kompatibilisierte NBR/SBR- Mischungen: Pyrolytische Degra-dation ihrer Ablagerungen als preisgünstige kohlenstoffreiche Quelle für die Herstellung von Kohlenstoff-Nanoröhrchen durch „Chemical Vapor Deposition“

Vulkanisierte Gummiabfälle · Organo-philes Montmorillonit · Pyrolyse · Kohlenstoff-Nanoröhrchen

Die Pyrolyse von Gummiabfällen, wel-che in einem horizontalen Pyrolysator unter katalytischen Bedingungen durchgeführt wurde, zeigt eine Reihe von Zusammensetzungsunterschieden auf. Sie ist eine, vom wirtschaftlichen Standpunkt ausgehend, geschätzte und überzeugende Methode, um mehrwan-dige Kohlenstoff-Nanoröhrchen (MW-CNTs) mit einem angemessenen Ertrag zu erzeugen. Die Gummiformulierun-gen, welche NBR und SBR enthalten, sind mit Hilfe eines amphiphobic orga-nisch-anorganischen Hybrids auf Basis von Na-Montmorillonit und einem per-manent mit dem Montmorillonit fest verknüpften oberflächenaktiven Modi-fizierungsmittel, Cetyltrimethylammo-niumbromid (CTAB), kompatiblisiert.

Figures and tables:By a kind approval of the authors.

IntroductionThe demand on rubber blend materials is continuously increasing due to their ex-ceptional properties and high perfor-mance, which cannot be acquired by the individual components of the blend. Un-fortunately, in most cases the compo-nents of such blends are immiscible. For this, the art of tailoring such materials depends mainly upon the engaged com-patibilizer whose role is to ensure ut-most compatibility and thereby enhance the properties maximally [1,2]. The dis-posal of such materials causes principal-ly environmental, public health and safe-ty problems [3]. This is attributed to the frequent disposal of these materials in landfills or in inadequately conditioned stockpiles. As an example, the piled tyres are known to provide breeding sites for mosquitoes that can spread serious dis-eases and fire hazards [3]. Several million tonnes of used rubber, mostly tyres, are estimated to be generated annually in North America, European Union and Ja-pan, only. A variety of reuse/recycle are in use, which include fillers in asphalt road pavement, as raw materials for second-ary products fabrication, reclaim rubber, and many others [3,4]. As the rubber materials are based mainly on carbon and hydrogen, and are not biodegradable therefore they present carbon rich sourc-es. Moreover, their heating values are higher than coal, as a result they are considered as good materials for energy and organic content recovery once good technologies are employed [5].Leung and Wang studied the thermal decomposition of scrap rubber using nonisothermal thermal gravimetric anal-ysis in a temperature range 20-600 oC and found that the heating rate had a significant effect on the pyrolysis effect while the powder size presented very modest effect [5].

Miranda et al reported the thermal degradation of rubber scrap corresponds

to moistures, decomposition of oils mix-tures and additives, while a second stage is supposed to be associated with the decomposition of rubber [3].

In the same context, Lin et al carried out pyrolytic treatment for styrene buta-diene rubber waste with a dynamic ther-mogravimetric reaction system and con-cluded that three main reactions contrib-ute to the pyrolysis process [6]. The first is associated with formation of volatiles at low temperatures and slow heating rate while the second and third stages represented the degradation of interme-diate volatile species.

Furthermore, Olazar and co-workers investigated a kinetic model based on the formation of intermediate fractions and parallel reactions which gave rise to other different sub-products; light non-condensable gases (C1-C4), non-aromat-ic liquids (C5-C10), aromatic hydrocar-bons (C5-C10), tar content (C11+) com-prising both aromatic and non-aromatic hydrocarbons and low grade carbon clack (char) [7].

NBR/SBR Blends Compatibilized with amphiphilic Montmorillonites: Pyrolytic Degradation of their Disposals as cheap Carbon Rich Sources for Fabrication of Carbon Nanotubes Via Chemical Vapor Deposition

AuthorsMagda E. Tawfik, Salwa H. El-Sabbagh, Hisham A. Essawy,Nady A. Fathy, Amina A. Attia, Giza, Egypt

Corresponding author: Hisham A. Essawy, Department of Polymers and Pigments, National Research Centre, Dokki 12622-Giza-EgyptEmail: [email protected]: +202 2 3337171


31KGK · 07-8 2016www.kgk-rubberpoint.de

On the other hand, Senneca and oth-ers [8] underwent a thermal gravimetric study with fast rate of heating on rubber scrap of polybutadiene and styrene-bu-tadiene copolymer with particle sizes of 1 and 3 mm and detected primary and secondary pyrolysis stages at low heat-ing rates, while at high heating rates it was not possible anymore to distinguish the pyrolysis stages. Additionally, Gonza-lez et al [9] pyrolyzed shredded automo-tive tyres (0.2-1.6 mm) and found the oil fraction, which composes mainly of ali-phatic, aromatic hydrocarbons and hy-droxyl compounds, reached maximum yield at 550-575 oC thus presented a good source of refined chemicals and liquid fuel.

The current work is investigating the practical possibility of using the decom-position products of specific developed formulations of vulcanized rubber scraps as carbon rich sources for the purpose of producing carbon nanotubes under cata-lytic conditions, passing through the py-rolysis products as precursors: oils, non-condensable gases, aliphatic and aro-matic hydrocarbons. The work will take place with special emphasis on compli-cated rubber compositions [10] in a trial for evaluating the possibility to replace the other much more precious materials used for this purpose such as polyolefins, particularly that huge amounts of tyre materials are discarded annually and can be exploited at no cost.

Experimental

MaterialsMontmorillonite (Na-MMT) with a parti-cle size of about 40-60 µm, was provided from Alfa Aesar GmbH & Co, Karlsruhe, Germany. Cetyltrimethylammonium bro-mide (CTAB) and γ-alumina were provided from Merck, Darmstadt-Germany. Iron ni-trate (99.9%) was purchased from Aldrich. Tetramethyl thiuram disulfide (TMTD), N-cyclohexyl-2-benzothiazolesulfenamide (CBS), zinc oxide and stearic acid were commercial grade products. Styrene–bu-tadiene rubber (SBR 1502) with 0.945 specific gravity, styrene content 23.5% and Mooney viscosity 48-58 ML (1+4) at 100 °C, was a gift from the Transportation and Engineering Company, Alexandria - Egypt. Acrylonitrile–butadiene rubber (NBR) was purchased from Bayer AG - Ger-many, under trade name perbunan, with a density 0.99 g/cm3, 34 ± 1 % acrylonitrile content and Mooney viscosity 65±7 ML (1+4) at 100 °C.

Modification of montmorillonite A dispersion of Na-Montmorillonite (Mont-0) was prepared in a suitable vol-ume of distilled water containing a pre-determined weight of a cationic surfac-tant (CTAB). Generally, the treatment is accomplished via partial/complete cat-ion exchange between the cationic sur-factant and the montmorillonite’s ex-changeable sodium based on the esti-mated cation exchange capacity[10]. Firstly, the temperature is increased slowly to 75 °C under stirring and con-tinued for 6 h. The clay was lastly sepa-rated by filtration and washed several times with distilled water and ethanol before drying at 70 °C overnight. The modified clay forms (Mont 50/100) were ground into fine powders using a mechanical blender. The number refers to the extent of organophilization, e.g. it ranges from 0 for virgin montmoril-lonite to 100 in case of complete or-ganophilization. Mont 0 is therefore the most hydrophilic while Mont 100 is maximally organophilized accordingly the organophilicity grows systematical-

ly at the expense of the hydrophilicity in the range from 0→100 [10].

Rubber blending and compounding The compounding of NBR and SBR was accomplished at a constant composition (50/50). Briefly, the components were mixed using a two-roll mill (the outer diameter is 470 mm while the slow roll was running at a 24 rev/min. at 1:1.4 gear ratio. Montmorillonite was added at a fixed loading (20 part per hundred (phr)) for each form at room tempera-ture along with other necessary compo-nents for processing and vulcanization: zinc oxide (5 phr), stearic acid (2 phr), CBS (1.5 phr), TMTD (0.3 phr) and sul-phur (2 phr). The mixing duration lasted totally for about 25 min. For simplicity, the blends are denoted H15 for NBR/SBR with 20 phr of Mont-0, M10 for NBR/SBR with 20 phr of Mont-50, and M22 for NBR/SBR with 20 phr of Mont-100. The curing characteristics of the blends were determined at 152±1 °C using oscillating disc rheometer, model 100 Monsanto - USA. The vulcanization

1

Fig. 1: Extent of realized compatibility for the imiscible NBR/SBR blend as a function of the clay philicity a) NBR/SBR, B) NBR/SBR/Mont-0, c) NBR/SBRMont-50, d) NBR/SBR/Mont-100.

a

c

b

d



of the blends started after 24 h from their preparation using electrically heat-ed platens at 4 MPa hence vulcanized sheets with approximate thickness of 2 mm were produced.

Preparation of Fe2O3/Al2O3 catalytic system by wet impregnation A wet impregnation process was em-ployed for the preparation of Fe2O3/Al2O3 as a catalyst for the carbon nanotubes formation. Briefly, about 5 wt. % of iron nitrate was dissolved in a small amount of distilled water. Then, the solution was added slowly to alumina powder under mechanical stirring at ambient tempera-ture followed by drying at 100 °C over-night. The dried mixture was thermally treated at 750 °C for 3 h under static air atmosphere in an electric furnace. Pyrolysis of rubber composites under catalytic conditions Shredded rubber samples (1.35 g of each individually) were pyrolyzed in a home-made horizontal flow furnace consisting of two compartments. The first compart-ment is allocated for the pyrolysis of the

sample at 850 °C. The flowing nitrogen carries the pyrolysis gaseous products into the other side (receiver) that con-tains the catalytic system (0.25 g Fe2O3 supported on alumina). The time was counted after the required temperature was reached (30 min).

CharacterizationsThe rubber samples were exposed to gold sputtering using EMITECH K550X sputter coater, England. The morphology was examined with Field emission scan-ning electron microscope (SEM-FEM), Model Quanta 250 FEG, operated at ac-celerating voltage 30 kV. The thermal decomposition for the rubber blends af-ter vulcanization was conducted on about 25 mg of each sample under nitro-gen atmosphere in the range from room temperature to 850 oC at a heating rate of 10 °Cmin. using Universal V4.7A TA in-strument. High resolution electron mi-croscopy images for the resulting carbon nanotubes (CNTs) were collected from transmission electron microscope (HR-TEM) operated at 120 kV (JEM-1230 model, Japan).

Results and discussionA great number of polymeric materials (mostly thermoplastics) have been used as stocks for synthesizing carbon nano-tubes (CNTs) in presence of catalysts [11-14]. Many researchers studied in-tensively the growth mechanism of CNTs and concluded that the surface energy plays a key role in the formation and growth. The whole process is de-pending upon catalytic combustion, which comprises two chemical reac-tions; degradation of the polymeric pre-cursors (solid phase reaction) and com-bustion of the degradation fragments (gas phase reaction). This motivated us to use a series of developed vulcanized NBR/SBR blends after inducing compat-ibilization with montmorillonites bear-ing wide range of surface activity. Sev-eral reasons lie behind this motivation: First, these types of materials are ther-moset after their vulcanization. Thus, their recycling is much complicated and greatly limited with respect to other more costly thermoplastic materials. Second, the scraps of these materials are considered as costless carbon-rich sources. Third, the mechanism by which they were compatibilized and the inter-esting developed morphologies after compatibilzation may presumably af-fect the formation and yield of the re-sulting CNTs, irrespective to the role of the catalyst and formation mechanism introduced in the report of Jiang et al [12, 15-18]. Fourth, the existence of or-ganophilic montmorillonite as a com-patibilizer in these formulations can act as a co-catalyst [12] for the degradation stage that happens before the CNTs for-mation. This was concluded as of the left proton acidic from the organophilic clay during the course of degradation can take part in the degradation of the rubber blend and enhance the pyrolysis products in the sense of more light frac-tions in the gas and liquid states.

It might thus be expected that the pyrolysis products will vary in type and quantity with the composition of the blend as the variable parameter for the introduced compositions in this work is the extent of organophilicity of the in-serted montmorillonite as compatibiliz-er. On the other hand, there is another factor opposing this, the utmost com-patibility (enhanced thermal and me-chanical resistance) is also a function of the clay organophilicity, which might lead to poor yield of pyrolysis products and/or heavier non useful fractions.

2

Fig. 2: FESEM of a) NBR/SBR, b) NBR/SBR/Mont-0, c) NBR/SBR/Mont-50, d) NBR/SBR/Mont-100 (scale line indicates 5 µm for a, while 10 µm for b-d).

a

c

b

d



The thermodegradation response of this blend is thought pass through differ-ent complicated stages in terms of the stability of each component and the ex-tent of co-interpenetration between the immiscible components, which is expect-ed to result in different degradation prod-ucts and accordingly influence the forma-tion of CNTs [19]. In the same way, Mizuno and co-workers found the matching be-tween the catalyst and carbon source is an important factor that influence the formation and yield of CNTs [20].

Fig. 1 presents a depiction for the developed various extents of co-inter-penetration of the blend components. It is noticeable that the extent of co-inter-penetration increases substantially. This principle was concluded and confirmed using imaging with electron microscopy as revealed in Fig. 2, which shows step-wise improvement from the state of phase separation to a variety of co-in-terpenetration levels between the blend components [18].

This co-interpenetration can be illus-trated on the light of the amphiphilicity of the inserted montmorillonite forms in case of M10 and M22. This may be a good platform for foreseeable intensifi-cation of not only the mechanical prop-erties but also the response to thermal decomposition.

The thermal degradation process has been taken place under nitrogen flow and the relevant traces are displayed in Fig. 3 for H15, M10 and M22. Based on our previous reports it was expected that as long as the untreated montmo-rillonite is used, poor compatibility is achieved between the NBR and SBR [10,15-18]. This is thought to lead to in-ferior resistance to thermal degrada-tion. However, it was not the case.

It can be dictated from these traces that the pyrolysis of M22 goes faster as compared to other samples especially above 250 °C, which can be linked with the sum of organic part of the inserted montmorillonite.

M22 continues to encounter more degradation in the range 250-450 °C, which means presumably enhancement of the thermal decomposition by the left proton acidic sites from the burned cat-ionic surfactant molecules on the sur-face. This translates strongly into much lighter hydrocarbon species. Above 450 °C the pyrolysis products include non-condensable gases, aliphatic and aromatic liquids. It is worthy to notice that the residual weight at 650 °C was

19% for H15 and 18% for M10 while de-clined in case of M22 to 13% only. This is principally convincing of more acidic sites resulting from degradation of a higher amount of the organic modifier part on the clay in case of M22, which accelerates the degradation process. This result is in conformity with the system-atic organophilization of the montmoril-lonite [10]. As a whole, the degradation temperature for the entire blend can be chosen in the range from 500 °C ahead. However, it was fixed in the current work at 850 °C to ensure complete degrada-tion.

Thus, the thermal degradation pro-files imply that the obtained degradation products can differ remarkably as a func-tion of the employed organoclay for the compatibilization of the blend. This fac-tor may play a role during the formation of CNTs under catalytic conditions in terms of the yield and growth comple-tion of the CNTs.

Different blend samples were pre-pared on a mass scale using the same

recipe while the variable was the extent of organophilicity of the inserted clay; untreated montmorillonite, which is highly hydrophilic (H15), moderately hy-drophobic montmorillonite (M10), and highly hydrophobic montmorillonite (M22). The samples were pyrolyzed in a horizontal pyrolyzer, where the liberated species during the thermal decomposi-tion of the samples were directed under nitrogen flow to move along into anoth-er compartment comprising a catalytic system (Fe2O3/Al2O3), a process that is known as chemical vapor deposition (CVD). The production of CNTs in a large scale using supported metal catalysts such as Fe, Ni, Co and Mo was reported before [21,22]. Typically, numerous stud-ies were carried out on the preparation of CNTs by such method using Fe2O3/Al2O3 as a catalyst [23-25].

The microstructure of the residual char of H15 is shown in Fig. 4a, whereas the carbonized product derived from the evoluted hydrocarbons after their coupling with the catalyst is shown in

Fig. 4: TEM images of a) charred residue of H15, b) CNTs produced from H15.

4

3

Fig. 3: Thermal degradation traces of H15, M10 and M22.

Temperature, °CW

eigh

t, %

0 200 400 600 800

1009080706050403020100

H15M10M22

a b



Fig. 4b. Surprisingly, the char product comprises some multi-walled CNTs (characterized by their hollow structure) among the remained clay, which signi-fies a role played either by the clay itself or perhaps one of the vulcanization ad-ditives (employed from the beginning to aid crosslinking of the rubber chains) in the formation of the CNTs. It is easy to note that the yield of the formed nano-tubes is agreeable keeping in mind the absence of a real specific catalyst. On the other hand, Fig. 4b indicates that under a more proper conditions (pro-duction in the presence of a catalyst) the formation of CNTs was still in prog-ress and their growth did not proceed to completion/perfection. Also, a lot of amorphous carbons exist, presumably while still awaiting their turn to be in-volved in a longer carbon chain, which reveals the lack of reasonable yield of light hydrocarbons as a result of the ex-istence of the clay in its un-organophi-

lized form. This ensures the necessity for Lewis acidic sites to enhance the degradation and liberate a higher amount of lighter hydrocarbon frac-tions, which are necessary for easier production of CNTs in high yield.

The carbonized products from M10 and M22 were also examined using TEM as shown in Figs. 5a and 6. As a first impression from the figures, both the yield and perfection of the produced carbon nanotubes in these cases differ remarkably as compared to H15. Additi-onally, they are characterized by some defective features like slopes and dislo-cations especially for the M22 based CNTs. Interestingly, the formation of some graphitic structures could also be found to be associated with CNTs for-mation (Fig. 5b).

In general, the lower yield shown in Fig. 5 supports a correlation between the philicity of the inserted clay as a compatibilizer and the yield of the re-

sulting CNTs. This is attributed from one side, as explained before, to the higher amount of lighter hydrocarbons evolved from H15 (this applies to the catalytic formation of CNTs) while it seems that no formation of CNTs took place in the residual ash for the former cases (M10 & M22). It should be stressed here that the high heating rate during the pyroly-sis process might be the reason for the low yield in general and prematuration of the formed CNTs thus this point will be investigated in more details in a fu-ture study.

Furthermore, the organoclay is known also to induce better enhanced compati-bility of the rubber components togeth-er, in comparison with the hydrophilic version of the clay. The organoclay with its formed acidic sites during the pyroly-sis will enhance the thermal degradation and overcome any possible enhance-ment in the thermal stability [26]. There-fore, little carbon content will remain in the combustion side, which accounts for the absence of CNTs in the residual ash (mainly clay). It is thus assumed in these cases that the liberated hydrocarbon fractions were lighter than those ob-tained from H15, which might explain the higher yield of CNTs (more appropri-ate conditions are provided for CNTs for-mation). Roughly, the extent of organo-philicity on the clay as a compatibilizing agent for NBR and SBR will create differ-ent physical environments for the car-bonization.

The CNTs were suggested to be formed via a mechanism that encoun-ters the attachment of the liberated hy-drocarbons on the catalytic particles [27]. According to this assumption, the formed graphite has an adequate high surface energy to provoke the assembly of a carbon cap on the surface of the catalyst. The cap will continue to grow up by adding more of the newly depos-iting carbon vapours until a hemisphere bears. In a subsequent step, a second cap will develop beneath the first one. The maturation of the formed tubes in this study via this assumption can be supported by the TEM image shown in Fig. 7 for a CNT precursor derived from M22 while still encapsulating the cata-lytic particles and just before the weld-ing of the hemispheres. As this mecha-nism assumes that the key factor for perfection of the resulting CNTs is the attachment of the condensing chemical vapours to a single catalyst particle, this postulates the use of as low as possible

Fig. 5: TEM images of a) CNTs, b) graphitic platelets, produced from M10.

5

Fig. 6: TEM images of CNTs produced from M22.

6

a b

a b



Fig. 7: TEM image of CNT precursor derived from M10 while the growth was still in pro-gress.

7of the catalyst. This may give rise to the need of more optimization of the cata-lyst content to ensure a systematic build up of greater number of carbons on in-dividual catalytic sites which leads eventually to well-defined CNTs. The existence of plentiful catalytic sites means many short carbon chains on lots of sites and accordingly imperfection.

ConclusionsScraps of vulcanized rubber blends con-sisting of the immiscible components NBR and SBR can be pyrolyzed under controlled conditions to produce CNTs. The extent of organophilicity of em-ployed compatibilizer (Na/CTA-Mont-morillonite) for the immiscible compo-nents has a marked influence on the yield and morphology of the produced CNTs from the pyrolysis process of each corresponding blend. This is thought to be dominated by two opposing factors: the compatibilizer action to enhance co-interaction between the NBR and SBR, which works for the thermal stability of the resulting blend (not good for a high-er yield of CNTs), in addition to the con-nected acidic sites formed during the pyrolysis, which speed up the thermal degradation process leading to lighter fractions of hydrocarbons, which are more favourable precursors for CNTs production.

AcknowledgmentThe authors are grateful to the adminis-tration of the National Research Centre for providing funding and facilities to achieve this work.

References[1] S.H. El-Sabbagh, M.E. Tawfik, F.M. Helaly, J.

Appl. Polym. Sci., 109, 2823 (2008).[2] M.E. Tawfik, F.M. Helaly, S.H. El-Sabbagh,

Kautschuke Gummi Kunststoffe (KGK), 64 (11-12), 42 (2011).

[3] M. Miranda, F. Pinto, I. Gulyurtlu, I. Cabrita, Fuel, 103, 542 (2013).

[4] E. Aylon, M.S. Callen, J.M. Lopez, A.M. Mastral, R. Murillo, M.V. Navarro, J. Anal. Appl. Pyrol., 74, 259 (2005).

[5] D.Y.C. Leung, C.L. Wang, Energy Fuel, 13, 421 (1999).

[6] J.P. Lin, C.Y. Chang, C.H. Wu, J. Chem. Techn. Biotechn., 66, 7 (1996).

[7] M. Olazar, G. Lopez, M. Arabiourrutia, G. Elor-di, R. Aguado, J. Bilbao, J. Anal. Appl. Pyrol., 81, 127 (2008).

[8] O. Senneca, P. Salatino, R. Chirone, Fuel, 78, 1575 (1999).

[9] J.F. Gonzalez, J.M. Encinar, J.L. Canito, J. Rodri-

guez, J. Anal. Appl. Pyrol., 58-59, 667 (2001).[10] H.A. Essawy, M.E. Tawfik, S.H. El-Sabbagh, J.

Elast. Plast., 46 (2), 113 (2014). [11] H. Nishino, R. Nishida, T. Matsui, N. Kawase,

I. Mochida, Carbon, 41, 2819 (2003).[12] Z. Jiang, R. Song, W. Bi, J. Lu, T. Tang, Carbon,

45, 449 (2007).[13] N. Hong, S. Nie, L. Song, Q. Tai, Mater. Lett.,

65, 2707 (2011).[14] S. Nie, X. Dong, C. Peng, B. Li, N. Hong, Y. Hu,

J. Polym. Res., 20 215 (2013). [15] H.A. Essawy, A. Khalil, M.E. Tawfik, S.H. El-

Sabbagh, J. Elast. Plast., 46 (6), 514 (2014).[16] H.A. Essawy, M.E. Tawfik, A. Khalil, S.H. El-

Sabbagh, Polym. Eng. Sci., 54, 942 (2014).[17] H.A. Essawy, M.E. Tawfik, S.H. El-Sabbagh, A.

El-Gendi, E. El-Zananti, H. Abdallah, Polym. Eng. Sci., 54, 1560 (2014).

[18] H.A. Essawy, A. El-Shakour, M.E. Tawfik, E.F. Mohamed, S.H. El-Sabbagh, M.A. El-Hashe-my, RSC Advances, 4, 33555 (2014).

[19] H.W. Wong, L.J. Brodbelt, Ind. Eng. Chem. Res., 40, 4716 (2001).

[20] K. Mizuno, K. Hata, T. Saito, S. Ohshima, M. Yumura, S.Iijima, J. Phys.Chem. B, 109, 2632 (2005).

[21] Y. Qin, Q. Zhang, Z. Cui, J. Catal., 223 (2), 389 (2004).

[22] C.P. Deck, K. Vecchio, Carbon, 44 (2), 267 (2006).

[23] X.Q. Wang, L. Li, N.J. Chu, Y.Pi Liu, H.X. Jin, H. Liang Ge, Mater. Res. Bull., 44, 422 (2009).

[24] V.I. Alexiadis, X.E. Verykios, Mater. Chem. Phys., 117 (2-3), 528 (2009).

[25] V.I. Alexiadis, N. Boukos, X.E. Verykios, Ma-ter. Chem. Phys., 128 (1-2), 96-108 (2011).

[26] M. Zanetti, G. Camino, P. Reichert, R. Mul-haupt, Macromol. Rap. Commun., 22, 176

(2001).[27] H.J. Dai, G.R. Andrew, N. Pasha, T. Andreas,

T.C. Daniel, E.S. Richard, Chem. Phys. Lett., 260, 471 (1996).

nbr/sbr blends compatibilized with amphiphilic …€¦ · secondary pyrolysis stages at low...

Documents