Preparation and properties of styrene–ethylene–butylene–styrene block copolymer/clay nanocomposites: I. Effect of clay content and compatibilizer types

BACKGROUND: Polymer/clay (silicate) systems exhibit great promise for industrial applications due to their ability to display synergistically advanced properties with relatively small amounts of clay loads. The effects of various compatibilizers on styrene–ethylene–butylene–styrene block copolymer (SEBS)/clay nanocomposites with various amounts of clay using a melt mixing process are investigated. RESULTS: SEBS/clay nanocomposites were prepared via melt mixing. Two types of maleated compatibilizers, styrene–ethylene–butylene–styrene block copolymer grafted maleic anhydride (SEBS‐g‐MA) and polypropylene grafted maleic anhydride (PP‐g‐MA), were incorporated to improve the dispersion of various amounts of commercial organoclay (denoted as 20A). Experimental samples were analyzed using X‐ray diffraction and transmission electron microscopy. Thermal stability was enhanced through the addition of clay with or without compatibilizers. The dynamic mechanical properties and rheological properties indicated enhanced interaction for the compatibilized nanocomposites. In particular, the PP‐g‐MA compatibilized system conferred higher tensile strength or Young's modulus than the SEBS‐g‐MA compatibilized system, although SEBS‐g‐MA seemed to further expand the interlayer spacing of the clay compared with PP‐g‐MA. CONCLUSION: These unusual results suggest that the matrix properties and compatibilizer types are crucial factors in attaining the best mechanical property performance at a specific clay content. Copyright © 2007 Society of Chemical Industry     

Flame-retardant properties of phenol–formaldehyde-type resins and triphenyl phosphate in styrene–acrylonitrile copolymers

The thermal and flame-retardant properties of phenol–formaldehyde-type resins (crosslinked and noncrosslinked) in mixtures with triphenyl phosphate and styrene–acrylonitrile resins were evaluated. The mixtures show a synergistic effect between triphenyl phosphate and novolacs. Those containing phenol–formaldehyde novolac resins are found to be most flame retardant. There does not seem to be a relationship between the oxygen index (OI) and UL 94 tests. Scanning electron microscopy analysis show a surface structure with cavities and stratification, very similar to that of intumescent additives. Evidence was found indicating that this flame-retardant system works in both the gas and condensed phase. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1067–1076, 1998     

Preparation and properties of a siloxane‐containing 2‐vinylpyridine–styrene–butadiene copolymer with water glass

A siloxane‐containing 2‐vinylpyridine–styrene–butadiene copolymer (PSBR/WG) was prepared from a 2‐vinylpyridine–styrene–butadiene copolymer (PSBR) latex and water glass. The water glass was added slowly, with stirring, to the PSBR latex. The latex mixture was stirred for 3 h at room temperature, and then, it was coagulated with 1N sulfuric acid producing a sulfate of PSBR with siloxane. The physical properties, such as the filling and stiffening effects of the hybrid polymer, and the vulcanizates were improved. An important advantage of this system is that it is possible to prepare the hybrid polymer simply, and the sodium ions formed in the reaction can also be easily removed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 891–899, 2006     

Novel method for preparation of quaternary ammonium ionomer from epoxidized styrene–butadiene–styrene triblock copolymer and its use as compatibilizer for blending of styrene–butadiene–styrene and chlorosulfonated polyethylene

A novel method for the preparation of a quaternary ammonium ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed by a ring‐opening reaction of epoxidized SBS with triethylamine hydrochloride in the presence of a phase transfer catalyst. The optimum conditions were studied. The ionomer was characterized by quantitative analysis, IR spectroscopy, and ¹H‐NMR spectroscopy. Its water absorbency, oil absorbency, dilute solution viscosity, and use as a compatibilizer for the blending of SBS and chlorosulfonated polyethylene (CSPE) were investigated. The results showed that, under optimum conditions, the epoxy groups can be completely converted to the quaternary ammonium groups. The IR spectrum did not exhibit the absorption peak for quaternary ammonium groups, whereas the ¹H‐NMR spectrum and titration method demonstrated it. With increasing ionic group content, the water absorbency of the ionomer increased whereas its oil absorbency decreased. These indicated the amphiphilic character of the SBS ionomer. The dilute solution viscosity of the ionomer in toluene/methanol (9/1) solvent increased with increasing quaternary ammonium group content. The ionomer was used as a compatibilizer for the blends of SBS and CSPE. The addition of a small amount of the ionomer to the blend enhanced the mechanical properties of the blends: 2 wt % ionomer based on the blend increased the tensile strength and ultimate elongation of the blend nearly 2 times. The blends of equal parts SBS and CSPE behaved as oil‐resistant thermoplastic elastomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1975–1980, 2006     

Influence of calcium carbonate filler and mixing type process on structure and properties of styrene–acrylonitrile/ethylene–propylene–diene polymer blends

The properties of styrene–acrylonitrile (SAN) and ethylene–propylene–diene (EPDM) blends containing different types of calcium carbonate filler were studied. The influence of mixing type process on the blend properties was also studied. Two different mixing processes were used. The first one includes mixing of all components together. The other process is a two‐step mixing procedure: masterbatch (MB; EPDM/SAN/filler blend) was prepared and then it was mixed with previously prepared polymer blend. Surface energy of samples was determined to predict the strength of interactions between polymer blend components and used fillers. The phase morphology of blends and their thermal and mechanical properties were studied. From the results, it can be concluded that the type of mixing process has a strong influence on the morphological, thermal, and mechanical properties of blends. The two‐step mixing process causes better dispersion of fillers in blends as well as better dispersion of EPDM in SAN matrix, and therefore, the finest morphology and improved properties are observed in blends with MB. It can be concluded that the type of mixing process and carefully chosen compatibilizer are the important factors for obtaining the improved compatibility of SAN/EPDM blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Kinetic behaviour of styrene–2‐hydroxyethyl methacrylate copolymerisation in microemulsion

The copolymerisation of styrene and 2‐hydroxyethyl methacrylate (2‐HEMA) in a three‐component oil‐in‐water microemulsion containing sodium dodecylsulfate as emulsifier was investigated as a function of temperature and concentration of potassium persulfate or hydrogen peroxide/ascorbic acid as initiator. Stable and transparent poly(styrene–2‐HEMA) latexes were produced. The latexes were characterised for particle size and number of particles by dynamic light scattering and transmission electron microscopy. The isolated products were characterised by ¹H NMR as well as by thermal analysis. The overall size of particles was observed to be in the range 22–38 nm. Attempts are made to examine the suitability of the existing mathematical models for homopolymerisation to account for the copolymerisation of styrene and 2‐HEMA. © 2002 Society of Chemical Industry     

Amphiphilic styrene–butadiene–styrene triblock copolymer grafted with polyoxyethylene

A styrene–butadiene–styrene triblock copolymer (SBS) was grafted with polyoxyethylene via a ring‐opening reaction of an epoxidized styrene–butadiene– styrene triblock copolymer (ESBS) with monocarboxylic‐group‐terminated methoxypoly(ethylene glycol) (CMPEG). The latter was prepared through the esterification of methoxypoly(ethylene glycol) with maleic anhydride. The optimum conditions for the preparation of the graft copolymer were studied. The graft copolymer was characterized with Fourier transform infrared spectrophotometry. Its water absorbency, oil absorbency, emulsifying property, phase‐transfer catalysis property in the Williamson solid–liquid reaction, and use as a compatibilizer in the blending of SBS with oil‐resistant chlorohydrin rubber (CHR) were also studied. The optimum conditions were a CMPEG/epoxy group molar ratio of 1.5, an N,N‐dimethyl aniline/ESBS concentration of 5 wt %, and an ESBS concentration of 12–14 g/100 mL at 75–80°C for 10 h. The polyoxyethylene content could reach 0.27 mmol/g. The graft copolymer absorbed a certain amount of water, fairly resisted kerosene, and possessed good emulsifying and phase‐transfer catalysis properties, both of which were enhanced with increasing polyoxyethylene graft content. The graft copolymer could be used as a compatibilizer for a blend of SBS and CHR. A 3 wt % concentration of the graft copolymer based on a 50/50 blend could increase both the tensile strength and ultimate elongation of the blend about 1.7 times. The blend behaved like an oil‐resistant thermoplastic elastomer. Scanning electron microscopy demonstrated the improved compatibility of the two components by the graft copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of molecular weight and arm number on properties of star‐shape styrene–butadiene–styrene triblock copolymer

A star‐shape styrene–butadiene–styrene triblock copolymer SBS (802) was synthesized and fractionated into four fractions coded as 802‐F1 (four arms), 802‐F2 (two arms), 802‐F3 (one arm), and 802‐F4 by repeating fractional precipitation. Their weight‐average molecular weight (M_w) was measured by size‐exclusion chromatography combined with laser light scattering to be 16.0 × 10⁴, 8.2 × 10⁴, 4.3 × 10⁴, and 1.19 × 10⁴, respectively. The samples were, respectively, compression‐molded and solution‐cast to obtain the sheets coded as 802C, 802‐F1C, 802‐F2C, and 802S, 802‐F1S, 802‐F2S. The structures and mechanical properties of the sheets were characterized by ¹H‐NMR, scanning electron microscope, wide‐angle X‐ray diffractometer, tensile testing, and dynamic mechanical thermal analysis. The results indicated that the compression‐molded 802‐F1C exhibited the higher tensile strength (σ_b, 28.4 MPa) and elongation at break (ε_b, 1610%), and its optical transmittance is much higher than those of 802C and 802‐F2C. This work revealed that the star‐shape SBS with four arms could be helpful in the enhancement of the properties as a result of good miscibility of the compression‐molded SBS sheets. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 832–840, 2005     

Behavior of ionomers of sulfonated styrene–butadiene–styrene triblock copolymer in polymer blends with crystalline polyolefins and as compatibilizer

The blends of ionomers of sulfonated (styrene–butadiene–styrene) triblock copolymer with two polyolefins as well as the blends of polystyrene (PSt) with two polar, oil‐resistant elastomers, i.e., chlorohydrin rubber (CHR) and chlorosulfonated polyethylene (CSPE), using the ionomer as compatibilizer were studied. The blends of the ionomer with polypropylene or high density polyethylene showed synergistic effects with respect to tensile strength. With increasing PSt content, the blends change their behavior from thermoplastic elastomer to toughened plastics. The synergism is probably because of the thermoplastic interpenetrating polymer networks formed in the blend. The blends exhibited high resistance against diesel oil or toluene. When PSt was blended with CHR or CSPE using the ionomer as compatibilizer, only 2 or 3% ionomer was needed to enhance the mechanical properties of the blends. The effect is due to the ion–polar interaction of the ionomer with the polar polymer. The enhanced compatibility of the blends by the ionomer was demonstrated by DSC and Scanning electron micrograph. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1887–1894, 2006     

Preparation and characterization of acrylonitrile–styrene–methylmethacrylate terpolymer as a compatibilizer for rubber blends

Acrylonitrile‐co‐styrene‐co‐methylmethacrylate (AN‐S‐MMA) terpolymer was prepared by bulk and emulsifier‐free emulsion polymerization techniques. The bulk and emulsion terpolymers were characterized by means of Fourierr transform infrared spectroscopy, ¹³C nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and elemental analysis. The kinetics of the terpolymerization were studied. The terpolymers were then incorporated into butadiene—acrylonitrile rubber (NBR)/ethylene propylene diene monomer rubber (EPDM) blends and into chloroprene rubber (CR)/EPDM blend. The terpolymers were then tested for potential as compatibilizers by using scanning electron microscopy and differential scanning calorimetry. The terpolymers improved the compatibility of CR/EPDM and NBR/EPDM blends. The physicomechanical properties of CR/EPDM and NBR/EPDM blend vulcanizates revealed that the incorporation of terpolymers was advantageous, since they resulted in blend vulcanizates with higher 100% moduli and with more thermally stable mechanical properties than the individual rubbers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3143–3153, 2003     

Curing behaviour and mechanical properties of dicarboxylated telechelic poly(ε-caprolactone)s/styrene–(epoxidized butadiene)–styrene triblock copolymer reactive blends

End-carboxylated telechelic poly(ε-caprolactone)s (XPCLs) with different molecular weights were blended into a triblock copolymer of styrene–(epoxidized butadiene)–styrene (ESBS) to investigate the curing behaviour and the mechanical properties of the XPCL/ESBS binary reactive blend. It was found that the time–torque cure curve showed a significant torque increase after a very short induction period, in which the degree of the torque increase depended on the molecular weight of XPCL. This indicates that substantial crosslinking reaction takes place between the XPCLs and the epoxidized polybutadiene of the ESBS. Stress–strain curves of the blends after cure depended on the molecular weight of XPCL and the blend ratio. The XPCL/ESBS blends had sufficient thermal stability to show elastomeric behaviour at elevated temperature above the glass transition of the styrene domains of ESBS because of formation of crosslinking points between unlike polymer components by the reactive blending. © 1999 Society of Chemical Industry     

Pore memory of macroporous styrene–divinylbenzene copolymers

The variation of the pore structure of styrene–divinylbenzene (S–DVB) copolymer beads with the drying conditions was investigated. Macroporous S–DVB copolymer beads with various DVB contents were prepared in the presence of toluene‐cyclohexanol mixtures as a diluent. It was found that the pores of 10¹‐nm radius, corresponding to the interstices between the microspheres, collapse upon drying of the copolymers from toluene. The collapsed pores reexpand if the copolymers were dried from methanol. The collapse–reexpansion process of the pores was found to be reversible, indicating that the actual pore structure formed during the crosslinking copolymerization is memorized by the copolymer network. The magnitude of the pore structure variation increased on worsening the polymer–diluent interactions during the gel formation process due to the simultaneous increase in crosslink density distribution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1055–1062, 1999     

Influence of styrene content on the hydrogenation of styrene–butadiene copolymer

A hydrogenated styrene–butadiene copolymer (HSBR) was prepared by a diimide reduction of SBR in the latex stage. The influence of the styrene content on various reaction parameters, namely, time, temperature, and concentration of the reactants and the catalyst was studied. A comparatively lower temperature, longer time, lesser amount of hydrogen peroxide, and higher amount of the catalyst are required to optimize the hydrogenation reactions of SBR with a higher styrene content. The diimide reduction of SBR is first order with respect to the olefinic substrate and the apparent activation energy increases with increase in the styrene level. All the hydrogenated copolymers were characterized with the help of IR, NMR, and DSC. The TGA data indicate a higher thermal stability of HSBR as compared to SBR in nitrogen, although an anomalous behavior is observed in air due to crosslinking and oxidation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1581–1595, 1999     

The effect of the architecture and concentration of styrene–butadiene compatibilizers on the morphology of polystyrene/low‐density polyethylene blends

The effect of styrene–butadiene block copolymers (SB) with varying number of blocks and length of styrene blocks on the morphology, rheology, and impact strength of 4/1 polystyrene/low‐density polyethylene (PS/LDPE) blends was studied. The scanning and transmission electron microscopy and X‐ray scattering were used for determination of the size of LDPE particles and the localization and structure of SB copolymers in blends. It is shown that the dependence of the LDPE particle size on the amount of added SB and localization of SB copolymers in blends is predominantly controlled by the length of their styrene blocks. It follows from thermodynamic considerations that the reason is the difference in composition asymmetry between SB with short and long styrene blocks. Coalescence of particles of SB having short styrene blocks at the surface of LDPE droplets and movement of SB with long styrene blocks to the PS–LDPE interface were observed during annealing of PS/LDPE/SB blends. Pronounced migration of SB copolymer during annealing shows that their localizations in blends in steady state on long steady mixing and at thermodynamic equilibrium are different. The values of tensile impact strength of PS/LDPE/SB blends correlate well with the size of LDPE particles and the amount of SB at the interface. Viscosity of PS/LDPE/SB depends on molecular structure of SB copolymers by a manner different from that of tensile impact strength. The results of this study and literature data lead to the conclusion that the compatibilization efficiency of SB copolymers for a certain polystyrene‐polyolefin pair is a function of not only molecular parameters of SB but also of the polystyrene/polyolefin ratio, the amount of SB in a blend, and mixing and processing conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2803–2816, 2006     

Some considerations concerning the dynamic mechanical properties of cured styrene–butadiene rubber/polybutadiene blends

The dynamic mechanical response of several binary mixtures of a styrene–butadiene copolymer and high cis‐polybutadiene has been studied. The loss tangent and shear modulus were measured with a free damping torsion pendulum at temperatures between 143 and 343 K in argon atmosphere. From the loss tangent data the glass transition temperature of each sample was evaluated. The results can be represented by the Fox equation that relates the glass transition temperature of the blend with that of constituent polymers. The influence in the loss tangent data of the crystallization of the high cis BR used in the blend is discussed. A study of the separation of the crystalline and amorphous parts in the polybutadiene using the storage modulus data is presented. Finally, the loss of crystallinity at different contents of SBR in the blend is analysed using the dynamic mechanical data. © 2000 Society of Chemical Industry     

Effects of maleated styrene–(ethylene‐co‐butene)–styrene on compatibilization and properties of nylon‐12,12/nylon‐6 blends

Effects of a maleated triblock copolymer of styrene–(ethylene‐co‐butene)–styrene (SEBS‐g‐MA) on compatibilization and mechanical properties of nylon‐12,12/nylon‐6 blends were investigated. The results showed that addition of SEBS‐g‐MA could improve the compatibility between nylon‐12,12 and nylon‐6. Nylon‐12,12 could disperse very well in nylon‐6 matrix, although the dispersion of nylon‐6 was poor when nylon‐6 was the dispersed phase. At a fixed nylon‐12,12/nylon‐6 ratio of 30/70, supertoughness was achieved with addition of 15% SEBS‐g‐MA in weight. Scanning electron microscopy of the impact‐fractured surface indicated that cavitation and matrix shear yielding were the predominant mechanisms of impact energy dissipation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1446–1453, 2004     

Blends of styrene–butadiene–styrene triblock copolymer and isotactic polypropylene: morphology and thermomechanical properties

A set of blends of styrene–butadiene–styrene triblock copolymer (SBS) and isotactic polypropylene (i‐PP) in a composition range 0–100 % polypropylene by weight was prepared in a twin screw extruder. The morphology of the blends has been studied by transmission electron microscopy. The blends present phase separation. Dynamic mechanical measurements show an improvement of the mechanical properties of SBS when i‐PP is the dispersed phase. This reinforcing effect can be observed even at high temperatures when i‐PP is in the rubbery state. The mechanical properties of the blends have been interpreted using Takayanagi's block model. The melting and crystallization behaviour of the i‐PP in the blends has been studied by differential scanning calorimetry. The fractionated crystallization phenomenon has been observed in the blends where i‐PP forms the dispersed phase. The results are consistent with the morphology shown by the blends, in particular, with its phase inversion, which occurs at a composition near to 50% i‐PP. © 2000 Society of Chemical Industry     

Preparation and properties of styrene–ethylene/butylene–styrene (SEBS)–clay hybrids

Styrene–ethylene/butylene–styrene triblock copolymer (SEBS)–clay hybrids were prepared by melt blending SEBS and organoclay using an internal mixer. Maleic anhydride modified SEBS (SEBS–MA) was used as a compatibilizer. X‐ray diffraction and transmission electron microscopy revealed that silicate layers of the clay were partially exfoliated and dispersed at a nanometer scale in the polymer matrix. Enhanced mechanical properties of these hybrids were observed from tensile and dynamic mechanical tests. Thermal degradation temperature of the hybrids was increased compared with pristine SEBS. Copyright © 2004 Society of Chemical Industry     

Effect of the addition of acrylonitrile/ethylene–propylene–diene monomer (EPDM)/styrene graft copolymer on the morphology–properties relationships in poly(styrene‐co‐acrylonitrile)/EPDM rubber blends

Blends of poly(styrene‐co‐acylonitrile) (SAN) with ethylene–propylene–diene monomer (EPDM) rubber were investigated. An improved toughness–stiffness balance of the SAN/EPDM blend was obtained when an appropriate amount of acrylonitrile–EPDM–styrene (AES) graft copolymer was added, prepared by grafting EPDM with styrene–acrylonitrile copolymer, and mixed thoroughly with both of the two components of the blend. Morphological observations indicated a finer dispersion of the EPDM particles in the SAN/EPDM/AES blends, and particle size distribution became narrower with increasing amounts of AES. Meanwhile, it was found that the SAN/EPDM blend having a ratio of 82.5/17.5 by weight was more effective in increasing the impact strength than that of the 90/10 blend. From dynamic mechanic analysis of the blends, the glass‐transition temperature of the EPDM‐rich phase increased from ?53.9 to ?46.2°C, even ?32.0°C, for the ratio of 82.5/17.5 blend of SAN/EPDM, whereas that of the SAN‐rich phase decreased from 109.2 to 108.6 and 107.5°C with the additions of 6 and 10% AES copolymer contents, respectively. It was confirmed that AES graft copolymer is an efficient compatibilizer for SAN/EPDM blend. The compatibilizer plays an important role in connecting two phases and improving the stress transfer in the blends. Certain morphological features such as thin filament connecting and even networking of the dispersed rubber phase may contribute to the overall ductility of the high impact strength of the studied blends. Moreover, its potential to induce a brittle–ductile transition of the glassy SAN matrix is considered to explain the toughening mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1685–1697, 2004     

Improvement of properties of silica‐filled styrene–butadiene rubber compounds using acrylonitrile–butadiene rubber

Since silica has strong filler–filler interactions and adsorbs polar materials, a silica‐filled rubber compound has a poor dispersion of the filler and poor cure characteristics. Improvement of the properties of silica‐filled styrene–butadiene rubber (SBR) compounds was studied using acrylonitrile–butadiene rubber (NBR). Viscosities and bound rubber contents of the compounds became lower by adding NBR to the compound. Cure characteristics of the compounds were improved by adding NBR. Physical properties such as modulus, tensile strength, heat buildup, abrasion, and crack resistance were also improved by adding NBR. Both wet traction and rolling resistance of the vulcanizates containing NBR were better than were those of the vulcanizate without NBR. The NBR effects in the silica‐filled SBR compounds were compared with the carbon black‐filled compounds. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1127–1133, 2001