Morphology and physical properties of SAN/NBR blends: The effect of AN content and melt viscosity of SAN

To study the effect of dispersed poly(butadiene-co-acrylonitrile) (NBR) rubber size on the physical properties of poly(styrene-co-acrylonitrile) (SAN)/NBR blends, SANs with various melt viscosities and acrylonitrile (AN) contents were examined. The dispersed size of NBR, whose AN content is 30 wt %, was reduced as the melt viscosity of the SAN matrix was increased or as the AN content of the SAN matrix was reduced in the range of 19–32 wt %. As the melt viscosity of the SAN matrix was increased, the damping peak of the NBR phase moved to a higher temperature, and as the AN content of SAN was reduced, the damping peak of the SAN phase moved to a lower temperature. Higher values of impact strength and elongation at break and reduced yield behavior at a low shear rate were observed at a finer dispersion of NBR. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 935–941, 1999     

Effect of dehydrochlorination of PVC on miscibility and phase separation of binary and ternary blends of poly(vinyl chloride), poly(ethylene-co-vinyl acetate) and poly(styrene-co-acrylonitrile)

The enhancement of miscibility at the lower critical solution temperature (LCST) of the blends poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN) and poly(vinyl chloride)/poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (PVC/EVA/SAN) was observed at the micron level. Such miscibility is attributed to the dehydrochlorination and formation of hydrogen bonds between blend components. However, macrolevel immiscibility of these blends heated to the LCST was observed. Such microdomain compatibility of these blends gives a synergistic character. Brittle-type failure observed for LCST samples testifies to the synergism in treated blends. ©1997 SCI     

Synthesis of poly(tetrafluoroethylene)/poly(butadiene) core-shell particles and their graft copolymerization

This article describes how to convert the unreactive surface of poly(tetrafluoroethylene) (PTFE) into poly(styrene-co-acrylonitrile) (SAN). Composite particles with a crosslinked poly(butadiene) (PB) shell covered over a PTFE core were prepared by an emulsifier-free seeded emulsion polymerization of butadiene in the presence of PTFE latex. It was found that the increase in the PB crosslink density resulted in depressing the formation of PB secondary particles. Then, styrene and acrylonitrile were able to graft onto PB shell in high efficiency of 70%. SAN-modified PTFE/PB core-shell particles could eventually be dispersed homogeneously in a SAN matrix. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:185–190, 1998     

Compatibility enhancement of ABS/PVC blends

The compatibilizing effect of poly(styrene-co-acrylonitrile) (SAN) whose acrylonitrile (AN) content is 25 wt % (SAN 25) in poly(acrylonitrile-co-butadiene-co-styrene) (ABS)/poly(vinyl chloride) (PVC) blend was studied when the AN content of the matrix SAN in ABS was 35 wt % (SAN 35). When some amount of matrix SAN 35 was replaced by SAN 25 in a ABS/PVC (50/50 by weight) blend, the mixed phase of SAN and PVC at the interface was thickened, and about a twofold increase of impact strength was observed. The changes in morphology, dynamic mechanical properties, and rheological properties by the compatibilizing effect of SAN 25 were observed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 705–709, 1998     

Fourier transform infrared spectroscopic studies of the poly(styrene-co-acrylonitrile) and poly (vinyl chloride-co-vinyl acetate) blends

The Fourier transform infrared (FTIR) spectroscopic studies of the poly-(styrene-co-acrylonitrile) (SAN) and poly(vinyl chloride-co-vinyl acetate) (VYHH) blends produced by different blending techniques, viz., solution blending, melt-blending, and also the co-precipitation methods of blending, were performed. In the case of miscible blend systems, substantial band shiftings took place, whereas immiscible blend systems showed slight or no band shifting. The miscible blends showed a substantial residual spectrum which was absent in the case of the immiscible system when a similar subtraction process was carried out. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 991–1000, 1997     

Effects of the polybutadiene/poly(styrene‐co‐acrylonitrile) ratio in a polybutadiene‐g‐poly(styrene‐co‐acrylonitrile) impact modifier on the morphology and mechanical behavior of acrylonitrile–butadiene–styrene blends

Polybutadiene‐g‐poly(styrene‐co‐acrylonitrile) (PB‐g‐SAN) impact modifiers with different polybutadiene (PB)/poly(styrene‐co‐acrylonitrile) (SAN) ratios ranging from 20.5/79.5 to 82.7/17.3 were synthesized by seeded emulsion polymerization. Acrylonitrile–butadiene–styrene (ABS) blends with a constant rubber concentration of 15 wt % were prepared by the blending of these PB‐g‐SAN copolymers and SAN resin. The influence of the PB/SAN ratio in the PB‐g‐SAN impact modifier on the mechanical behavior and phase morphology of ABS blends was investigated. The mechanical tests showed that the impact strength and yield strength of the ABS blends had their maximum values as the PB/SAN ratio in the PB‐g‐SAN copolymer increased. A dynamic mechanical analysis of the ABS blends showed that the glass‐transition temperature of the rubbery phase shifted to a lower temperature, the maximum loss peak height of the rubbery phase increased and then decreased, and the storage modulus of the ABS blends increased with an increase in the PB/SAN ratio in the PB‐g‐SAN impact modifier. The morphological results of the ABS blends showed that the dispersion of rubber particle in the matrix and its internal structure were influenced by the PB/SAN ratio in the PB‐g‐SAN impact modifiers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2165–2171, 2005     

Rheological behavior of blends of poly(methyl methacrylate) (PMMA) and poly(acrylonitrile-stat-styrene)-graft-polybutadiene (ABS)

The rheological behavior of blends of poly(methyl methacrylate) (PMMA) and poly(acrylonitrile-stat-styrene)-graft-polybutadiene (ABS) was investigated using a cone-and-plate rheometer. The rheological properties measured were shear stress (σ₁₂), viscosity (η), and first normal stress difference (N₁) as functions of shear rate (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma$ \end{document}) in steady shearing flow, and storage modulus (G′) and loss modulus (G″) as functions of frequency (ω) in oscillatory shearing flow. It has been found that the rheological behavior of blends of ABS and PMMA was very similar to that of blends of poly(styrene-stat-acrylonitrile) (SAN) and PMMA, in that N₁ in logarithmic plots of N₁ versus σ₁₂, and G′ in logarithmic plots of G′ versus G″, vary regularly with blend composition. This has led us to conclude that the rubber particles that are grafted on an SAN resinous matrix in ABS resin plays only a minor role in influencing the compatibility of ABS/PMMA blends, and that the SAN chains attached to the surface of rubber particles, and the SAN matrix phase, play a major role in compatibilizing ABS resin with PMMA.     

Novel blends of alternating propene-carbon monoxide copolymers and styrenic copolymers

Summary Alternating propene-carbon monoxide copolymers (P-CO) were melt-blended with polystyrene, poly(styrene-co-acrylonitrile) (SAN), and with poly(styrene-co-maleic anhydride) (SMA). P-CO forms homogeneously miscible blends with SAN containing 25 wt% AN at the investigated blend compositions. The transparent blends have single, intermediate glass transition temperatures that fit the Fox equation. The elastic properties of P-CO at room temperature disappear upon blending with SAN because the T _g is driven above RT. Polystyrene and SMA are not miscible with P-CO and form heterogeneous blends with two glass transitions. This demonstrates that both the polarity of the styrenic copolymer and the nature of the comonomer govern its phase behavior. Received: 14 January 1999/Revised version: 19 April 1999/Accepted: 19 April 1999     

Rheological studies of the poly(styrene-co-acrylonitrile) and poly(vinyl chloride-co-vinyl acetate) blends

The rheological studies of the poly(vinyl chloride-co-vinyl acetate) and poly(styrene-co-vinyl acetate) and poly(styrene-co-acrylonitrile) blends were performed by a Brabender Rheotron at three different temperatures and also at different shear rates. Flow curves of the blends at different temperatures were drawn. The flow behavior index and, also, zero-shear viscosity of the blends at different temperatures were determined. From the flow curves, it has been found that as shear stress increases, melt viscosity decreases at all temperatures, indicating that pseudoplastic behavior and experimental values lies above the line of the log-additivity value and below the line of the additivity rule of mixture. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2577–2583, 1998     

Synthesis of poly(styrene-co-acrylonitrile) copolymer brushes on silica nanoparticles through surface-initiated polymerization

In the present investigation, silica nanoparticles have been coated with poly(styrene-co-acrylonitrile) (SAN) copolymer brushes synthesized via surface-initiated atom transfer radical polymerization (ATRP). In the initial step, silica nanoparticles were functionalized with triethoxysilane-based ATR initiator, 6-(2-bromo-2-methyl) propionyloxy hexyl triethoxysilane. Successful formation of the covalent linkages between ATRP initiator and silica nanoparticles is further corroborated using thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The surface initiated ATRP of the styrene and the acrylonitrile mediated by a copper complex was carried out using the initiator fixed silica nanoparticles in the presence of a sacrificial (free) initiator. The polymerization is preceded in a living manner in all examined cases, producing nanoparticles coated with well-defined poly(styrene-co-acrylonitrile) (SAN) brushes with molecular weight in the range of 12–22 kDa. SAN-grafted silica nanoparticles were characterized using TGA which showed significant weight loss in the temperature range of 340–420 °C confirming the formation of the polymer brushes on the surface with graft densities in the range of 0.109–0.190 chains/nm². Successful formation of the SAN copolymer brushes are further characterized by FTIR and proton nuclear magnetic resonance spectroscopy techniques. Differential scanning calorimetric studies revealed that the SAN copolymer grafted onto silica nanoparticles exhibits higher glass transition temperatures than free SAN copolymers. Transmission electron microscopy and dynamic light scattering studies revealed that the SAN copolymer-grafted silica nanoparticles showed relatively fine dispersion in organic solvents such as tetrahydrofuran, when compared to bare silica nanoparticles.     

Influence of acrylonitrile–butadiene–styrene (ABS) morphology and poly(styrene‐co‐acrylonitrile) (SAN) content on fracture behavior of ABS/SAN blends

This study attempted to correlate morphological changes and physical properties for a high rubber content acrylonitrile–butadiene–styrene (ABS) and its diluted blends with a poly(styrene‐co‐acrylonitrile) (SAN) copolymer. The results showed a close relationship between rubber content and fracture toughness for the blends. The change of morphology in ABS/SAN blends explains in part some deviations in fracture behavior observed in ductile–brittle transition temperature shifts. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2606–2611, 2004     

Enhancement of the mechanical properties of poly(styrene-co-acrylonitrile) with poly(methyl methacrylate)-grafted multiwalled carbon nanotubes

Poly(methyl methacrylate) (PMMA) was grafted onto multiwalled carbon nanotubes (MWNTs). Composites of PMMA-grafted MWNTs and poly(styrene-co-acrylonitrile) (SAN) were prepared by solution casting from tetrahydrofuran. Since PMMA is miscible with SAN, the two polymers mix intimately to facilitate the dispersion of PMMA-grafted MWNTs in the SAN matrix. The intimate mixing is evidenced by the transparency of the composites. The incorporation of PMMA-grafted MWNTs to SAN (effective MWNT content=0.5-2 wt%) leads to increases in storage modulus at 40 °C, Young's modulus, tensile strength, ultimate strain, and toughness by 90, 51, 99, 184 and 614%, respectively. Such simultaneous increases in stiffness, strength, ductility and toughness of a polymer by rigid fillers are rarely observed.     

Effects of acrylonitrile content on the properties of clay-dispersed poly(styrene-co-acrylonitrile) copolymer nanocomposite

Summary Clay-dispersed nanocomposites have been prepared by simple melt-mixing of two components, i.e. poly(styrene-co-acrylonitrile) copolymers with different contents of acrylonitrile comonomer and two different kinds of organophilic clay (Cloisite? 25A and Cloisite? 30A), with a twin screw extruder. Dispersion behavior of 10-?-thick silicate layers of clay in the nanocomposites was investigated by using an X-ray diffractometer and a transmission electron microscope. It was found that acrylonitrile comonomer incorporated into poly(styrene-co-acrylonitrile) copolymers accelerates intercalation of the copolymers into the galleries of silicate layers modified with an organic intercalant. The faster intercalation of a matrix polymer leads to the better dispersion of silicate layers in the matrix polymer. Received: 1 May 2000/Revised version: 10 July 2000/Accepted: 24 July 2000     

Study of the miscibility of poly(ethyl methacrylate-co-4-vinylpyridine)/poly(styrene-co-cinnamic acid) blends

Summary The miscibility of a series of poly(ethyl methacrylate-co-4-vinylpyridine) with poly(styrene-co-cinnamic acid), is investigated by differential scanning calorimetry. The results show that each blend is miscible as ascertained by a single composition dependent glass transition temperature. The Tg's of the blends exhibit positive deviations from the weight average Tg's of the blend components. The thermograms data exploited according to the Kwei and Schneider approaches suggest the occurrence of strong specific intermolecular attractive interactions within the binary systems. The strength of these interactions, as estimated from the Kwei q-values, increases with the proton donor and proton acceptor contents in the copolymers. Received: 23 January 1999/Revised version: 29 April 1999/Accepted: 1 June 1999     

Thermoplastic elastomeric blend of nitrile rubber and poly(styrene‐co‐acrylonitrile). I. Effect of mixing sequence and dynamic vulcanization on mechanical properties

The effects of dynamic vulcanization and blend ratios on mechanical properties and morphology of thermoplastic elastomeric (TPE) compositions, based on blends of nitrile rubber (NBR) and poly(styrene‐co‐acrylonitrile) (SAN), were studied. The TPE composition prepared by adding a rubber‐curatives masterbatch to softened SAN yields higher mechanical properties than that prepared by adding curatives to the softened plastic–rubber preblend. The blends having a higher rubber–plastic ratio (60 : 40 to 80 : 20) display thermoplastic elastomeric behavior, whereas those having a higher plastic–rubber ratio (50 : 50 to 90 : 10) display the behavior of impact‐resistant plastics. DSC studies revealed that NBR and SAN are thermodynamically immiscible. SEM studies of the thermoplastic elastomeric compositions show that SAN forms the matrix in which fine particles of NBR form the dispersed phase. It was further confirmed by dynamic mechanical thermal analysis. Dynamic vulcanization causes a decrease in the size of dispersed particles and improvement in mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1976–1987, 2003     

Miscibility studies of polymer blends by viscometry methods

The intrinsic viscosities of blends of poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vinyl chloride)/poly(styrene-co-acrylonitrile) (PVC/SAN), and poly(ethylene-co-vinyl acetate)/poly(styrene-co-acrylonitrile) (EVA/SAN) have been studied in cyclohexanone as a function of blend composition. In order to predict the compatibility of polymer pairs in solution, the interaction parameter term, Δb, obtained from the modified Krigbaum and Wall theory, and the difference in the intrinsic viscosities of the polymer mixtures and the weight average intrinsic viscosities of the two polymer solutions taken separately are used. © 1994 John Wiley & Sons, Inc.     

Effect of styrene-co-acrylonitrile on cold crystallization and mechanical properties of poly(ethylene terephthalate)

Blends of poly(ethylene terephthalate) (PET) with small amounts of styrene-co-acrylonitrile (SAN) were prepared by melt blending, and cold crystallization of these mixtures was investigated by means of differential scanning calorimetry. The results suggest that SAN interacts with the amorphous phase of PET, as observed by variations in the glass transition temperature and in the morphology of the blends, analyzed by scanning electron microscopy. The addition of 1% SAN promoted a significant reduction in the crystallization rate of PET, in a manner similar to that of an antinucleating agent. However, the crystallinity of the PET/SAN blends was comparable with that of neat PET; hence, mechanical properties were only slightly affected. Kinetic parameters were determined using Avrami theory; Avrami plots presented a nonlinear behavior at the end of crystallization, indicating that cold crystallization proceeds in two stages. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Delamination failure mechanisms in microlayers of polycarbonate and poly(styrene-co-acrylonitrile)

The peel strength and delamination failure mode of coextruded microlayer sheets consisting of alternating layers of polycarbonate (PC) and poly(styrene-co-acrylonitrile) (SAN) were studied with the T-peel test. Four delamination modes were observed: two modes where the crack propagated along the PC–SAN interface and two other modes where the crack propagated through crazes in the SAN. The SAN layer thickness determined whether crack propagation was interfacial or through crazes. Crazing and crack propagation through crazes were observed only if the SAN layer was thicker than 1.5 μm. As the thickness of the SAN layer increased, the amount of crazing in front of the crack tip and the amount of craze fracture gradually increased; the peel strength increased accordingly. If the SAN layers were thinner than 1.5 μm and the PC layers were relatively thick, the crack propagated along a single interface. The peel strength for this delamination mode was the lowest and equal to about 90 J/m², independent of layer thicknesses. This delamination mode came closest to providing a ”real” measure of the adhesive toughness of PC to SAN. With both interfacial and craze delamination, the crack could move from layer to layer if the PC was thin enough. Tearing of the relatively thin PC layers increased the peel strength of the multiple-layer delamination modes. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:793–805, 1998     

Thermal properties of blends of poly(hydroxybutyrate‐co‐hydroxyvalerate) and poly(styrene‐co‐acrylonitrile)

Thermal properties of blends of poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) and poly(styrene‐co‐acrylonitrile) (SAN) prepared by solution casting were investigated by differential scanning calorimetry. In the study of PHBV‐SAN blends by differential scanning calorimetry, glass transition temperature and melting point of PHBV in the PHBV‐SAN blends were almost unchanged compared with those of the pure PHBV. This result indicates that the blends of PHBV and SAN are immiscible. However, crystallization temperature of the PHBV in the blends decreased approximately 9–15°. From the results of the Avrami analysis of PHBV in the PHBV‐SAN blends, crystallization rate constant of PHBV in the PHBV‐SAN blends decreased compared with that of the pure PHBV. From the above results, it is suggested that the nucleation of PHBV in the blends is suppressed by the addition of SAN. From the measured crystallization half time and degree of supercooling, interfacial free energy for the formation of heterogeneous nuclei of PHBV in the PHBV‐SAN blends was calculated and found to be 2360 (mN/m)³ for the pure PHBV and 2920–3120 (mN/m)³ for the blends. The values of interfacial free energy indicate that heterogeneity of PHBV in the PHBV‐SAN blends is deactivated by the SAN. This result is consistent with the results of crystallization temperature and crystallization rate constant of PHBV in the PHBV‐SAN blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 673–679, 2000     

A new class of transparent polymeric materials. III. Miscible blends of poly(N-methylmaleimide-alt-isobutene) with poly(acrylonitrile-co-styrene) and the properties of the blends

The blend miscibility of poly(N-methylmaleimide-alt-isobutene) [poly-(MeMI-IB)] with poly(acrylonitrile-co-styrene) (SAN) was investigated by means of measurement of the glass transition temperature of the blends. Poly(MeMI-IB) was found to be miscible with SAN of a specific range of acrylonitrile (AN) contents in the copolymer to produce transparent moldings. The refractive index changed from 1.58 to 1.53 and the dispersion decreased with increasing the amount of poly(MeMI-IB) in the blends. The stress optical coefficient of poly(MeMI-IB) was found to be reduced by the blending of SAN. The glass transition temperature, flexural modulus, and surface hardness of the blends increased with an increase in the amount of poly(MeMI-IB) in the blend. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 925–929, 1997