Morphology and mechanical properties of ABS blends prepared from emulsion‐polymerized PB‐g‐SAN impact modifier with AIBN as initiator

A series of PB‐g‐SAN impact modifiers (polybutadiene particles grafted by styrene and acrylonitrile) are synthesized by seed emulsion copolymerization initiated by oil‐soluble initiator, azobisiobutyronitrile (AIBN). The ABS blends are obtained by mixing SAN resin with PB‐g‐SAN impact modifiers. The mechanical behavior and the phase morphology of ABS blends are investigated. The graft degree (GD) and grafting efficiency (GE) are investigated, and the high GD shows that AIBN has a fine initiating ability in emulsion grafting of PB‐g‐SAN impact modifiers. The morphology of the rubber particles is observed by the transmission electron microscopy (TEM). The TEM photograph shows that the PB‐g‐SAN impact modifier initiated by AIBN is more likely to form subinclusion inside the rubber particles. The dynamic mechanical analysis on ABS blends shows that the subinclusion inside the rubber phase strongly influences the T_g, maximum tan δ, and the storage modulus of the rubber phase. The mechanical test indicates that the ABS blends, which have the small and uniform subinclusions dispersed in the rubber particles, have the maximum impact strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Influence of the tert‐dodecyl mercaptan content in poly(acrylonitrile‐butadiene‐styrene) on properties of chlorinated polyvinyl chloride/poly(acrylonitrile‐butadiene‐styrene) blends

A series of poly(acrylonitrile‐butadiene‐styrene) (ABS) grafting modifiers were synthesized by emulsion grafting poly(acrylonitrile‐styrene) (SAN) copolymer onto polybutadiene (PB) latex rubber particles. The chain transfer reagent tert‐dodecyl mercaptan (TDDM) was used to regulate the grafting degree of ABS and the molecular weight of SAN copolymers. By blending these ABS modifiers with Chlorinated polyvinyl chloride (CPVC) resin, a series of CPVC/ABS blends were obtained. The morphology, compatibility, and the mechanical properties of CPVC/ABS blends were investigated. The scanning electron microscope (SEM) studies showed that the ABS domain all uniformly dispersed in CPVC matrix. Dynamic mechanical analyses (DMA) results showed that the compatibility between CPVC and SAN became enhanced with the TDDM content. From the mechanical properties study of the CPVC/ABS blends, it was revealed that the impact strength first increases and then decreases with the TDDM content, which means that the compatibility between CPVC and the SAN was not the only requirement for maximizing toughness. The decreasing of tensile strength and the elongations might attribute to the lower entanglement between chains of CPVC and SAN. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

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     

Fractographic analysis of the crack resistance of styrene–acrylonitrile/polybutadiene‐g‐styrene–acrylonitrile blends as evaluated by the essential work of fracture method

The fracture surfaces and deformation micromechanisms of styrene‐co‐acrylonitrile (SAN)/polybutadiene‐g‐styrene‐co‐acrylonitrile (PB‐g‐SAN) blends with the compositions ranging from 65/35 to 0/100 were studied with a scanning electron microscopy technique. The results were compared to the essential work of fracture parameters obtained in a previous study conducted on double‐edge notched tension specimens. Different plastic damage mechanisms were observed, and they depended on the blend composition. For blends of 65/35 and 45/55, a high degree of rubber particle cavitation and multiple cracking followed by the massive shear yielding of the matrix were found to be the main source of energy dissipation during crack growth. Within this compositional range, more intense plastic damage in a larger volume of material, especially at the notched region, was observed as the concentration of the rubbery phase increased. For the 25/75 blend, the prevailing mechanism was pure shear yielding without any sign of cavitation inside the particles, and the fracture surface became relatively flat and was covered with aligned small microcracks. This sample showed the highest specific essential work (w_e) value among the blends examined in the previous study. For the samples containing concentrations of dispersed phase higher than 75%, the shear yielding process gradually became less important with the progressive importance of multiple crazing so that high‐magnification micrographs revealed extensive microcracking/crazing both inside and between the rubber particles, as the only active deformation micromechanism for neat PB‐g‐SAN. The variation w_e and specific plastic work of fracture with the PB‐g‐SAN phase content were successfully explained in terms of prevalent deformation mechanisms. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40072.     

Toughness of SMI‐modified ABS alloys and the associated deformation behavior

The mechanical toughness of modified ABS (acrylonitrile–butadiene–styrene) alloys was evaluated using Izod impact, tensile, and compact tension tests. The modified ABS alloys contain 20 wt % of styrene–N‐phenylmaleimide (SMI) that is added to enhance the thermal resistance of the ABS. In this study, the effects of matrix composition, rubber/matrix adhesion, and rubber particle structure on the alloy toughness were investigated. Results from the tensile test and Izod impact test ranked the alloys in an order that is different from that given by K_Ii (stress intensity factor for crack initiation), measured from compact tension specimens. This is due to the difference in energy‐absorption characteristics for crack initiation and crack growth. The conclusion is supported by optical micrographs on the deformation zone size. The microdeformation behavior of the alloys was examined using transmission electron microscopy (TEM), which revealed different rubber‐toughening mechanisms between Izod and tensile specimens. The former contains numerous extensive crazes, while the latter, only a very few short crazes, except in regions within a few micrometers from the fracture surface. The dominant matrix deformation mechanism for the tensile specimens is believed to be shear deformation. Another interesting observation from the study is rubber particle cavitation, commonly observed in tensile specimens and Izod specimens with solid rubber particles; it did not occur in the Izod specimens containing salami‐type rubber particles. This is attributed to the salami structure that increased the straining rate for the rubber phase, leading to ductile–brittle transition of the rubber. The transition to brittle deformation of the rubber phase prevented rubber particle cavitation. The microscopic examination indicated that toughening mechanisms by the rubber particles can be very different among the mechanical tests, which should be taken into account for the rubber toughening of polymers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1543–1553, 1999     

Toughening of polyvinylchloride by methyl methacrylate–butadiene–styrene core–shell rubber particles: Influence of rubber particle size

An analysis was made on the effects of rubber particle size on the mechanical properties and deformation mechanisms of transparent polyvinyl chloride (PVC) blends containing core–shell methyl methacrylate–butadiene–styrene (MBS) impact modifiers. The critical interparticle distance was found not to be the criterion for the brittle‐ductile transition in the blends. In tensile tests, the blends with larger (100–280 nm) rubber particles exhibited intense stress‐whitening, while one blend with small (83 nm) rubber particles showed only slight stress‐whitening. These differences were due to an increase in resistance to cavitation with decreasing rubber particle size. Transmission electron microscopy studies on blends with a bimodal distribution of particle sizes showed that in the whitened zone of Izod specimens the larger rubber particles cavitated and expanded on yielding, while the smaller particles remained intact. However, Izod test results showed that small MBS rubber particles can toughen the PVC matrix very effectively, especially at low temperatures and at low rubber concentrations. The deformation mechanisms responsible for these effects were discussed. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Blends of bisphenol A polycarbonate and rubber‐toughened styrene–maleic anhydride copolymers

The morphology and mechanical properties of polycarbonate (PC) blends with rubber‐toughened styrene–maleic anhydride copolymer materials (TSMA) were investigated and compared with the properties of blends of PC with acrylonitrile–butadiene–styrene (ABS) materials. The PC/TSMA blends showed similar composition dependence of properties as the comparable PC/ABS blends. Polycarbonate blends with TSMA exhibited higher notched Izod impact toughness than pure PC under sharp‐notched conditions but the improvements are somewhat less than observed for similar blends with ABS. Since PC is known for its impact toughness except under sharp‐notched conditions, this represents a significant advantage of the rubber‐modified blends. PC blends with styrene–maleic anhydride copolymer (SMA) were compared to those with a styrene–acrylonitrile copolymer (SAN). The trends in blend morphology and mechanical properties were found to be qualitatively similar for the two types of copolymers. PC/SMA blends are nearly transparent or slightly pearlescent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1508–1515, 1999     

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     

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     

Influence of ABS type on morphology and mechanical properties of PC/ABS blends

The morphology and the mechanical properties of polycarbonate (PC) blends with different acrylonitrile–butadiene–styrene (ABS) materials were investigated. PC/ABS blends based on a mass-made ABS with 16% rubber and large (0.5–1μm) rubber particles are compared to blends based on an emulsion-made ABS with 50% rubber and small, monodisperse (0.12 μm) rubber particles over the full range of blend compositions. The blends with the bulk ABS showed excellent impact strength for most compositions, and those containing 50 and 70% PC exhibited ductile to brittle transition temperatures below that of PC. The blends with the emulsion ABS showed excellent toughness in sharp notch Izod impact tests at room temperature and in standard notch Izod impact tests at low temperatures near the T_g of the rubber. By melt blending the various ABS materials with a styrene–acrylonitrile (SAN 25) copolymer, materials with lower rubber concentrations were obtained. These materials were used in blends with PC to make comparisons at constant rubber concentration of 5, 10, and 15%. The results of this investigation show that brittle ABS materials can produce tough PC–ABS blends. It is apparent that small rubber particles toughen PC–ABS blends at lower rubber concentrations and at lower temperatures than is possible with large rubber particles. However, additional work is needed to understand the nature of toughening in these PC–ABS blends with different rubber phase morphologies. It is of particular interest to understand the exceptional ductility of some of the blends at low temperatures. © 1994 John Wiley & Sons, Inc.     

Study on the microphase structure and mechanical properties of the blends of acrylonitrile–butadiene–styrene and sodium sulphonated styrene–acrylonitrile ionomer

The tensile properties of the blends containing neat acrylonitrile–butadiene–styrene (ABS), styrene–acrylonitrile (SAN) and the sodium sulphonated SAN ionomer have been investigated as a function of ion content of the ionomer in the blend. The tensile toughness and strength of the blends showed maximum values at a certain ion content of the ionomer in the blend. This is attributed to the enhanced tensile properties of the SAN ionomer by introduction of ionic groups into SAN and the interfacial adhesion between the rubber and matrix phase in the blend. The interfacial adhesion was quantified by NMR solid echo experiments. The amount of interphase for the blend containing the SAN ionomer with low ion content (3·1mol%) was nearly the same as that of ABS, but it decreased with the ion content of the ionomer for the blend with ion content greater than 3·1mol%. Changing the ionomer content in the blends showed a positive deviation from the rule of mixtures in tensile properties of the blends containing the SAN ionomer with low ion content. This seems to result from the enhanced tensile properties of the SAN ionomer, interfacial adhesion between the rubber and matrix, and the stress concentration effect of the secondary particles. © 1998 SCI.     

Blends of poly(vinyl chloride) with α‐methylstyrene‐acrylonitrile‐butadiene‐styrene copolymer: Thermal properties,mechanical properties,and morphology

Binary blends of poly(vinyl chloride) (PVC) with α‐methylstyrene‐acrylonitrile‐butadiene‐styrene copolymer (AMS‐ABS) were prepared via melt blending. A single glass transition temperature (T_g) was observed by differential scanning calorimetry, thus indicating that PVC is miscible with the α‐methylstyrene‐acrylonitrile‐styrene in AMS‐ABS. The results from attenuated total reflection Fourier transform infrared spectra indicated that specific strong interactions were not available in the blends. With increasing amounts of AMS‐ABS, both heat distortion temperature and thermal stability were increased considerably. With regard to mechanical properties, flexural and tensile properties decreased with increasing AMS‐ABS content. A synergism was observed in impact strength. The morphology of both impact‐fractured and tensile‐fractured surfaces, observed by scanning electron microscopy, correlated well with the mechanical properties. It is suggested that there was a transition of fracture mechanisms with the changing composition of the binary blends—from shear yielding for blends rich in PVC to cavitation for blends rich in AMS‐ABS. J. VINYL ADDIT. TECHNOL., 19:1–10, 2013. © 2013 Society of Plastics Engineers     

Synthesis of sub‐micrometer core–shell rubber particles with 1,2‐azobisisobutyronitrile as initiator and deformation mechanisms of modified polystyrene under various conditions

BACKGROUND: Sub‐micrometer core‐shell polybutadiene‐graft‐polystyrene (PB‐g‐PS) copolymers with various ratios of polybutadiene (PB) core to polystyrene (PS) shell were synthesized by emulsion grafting polymerization with 1,2‐azobisisobutyronitrile (AIBN) as initiator. These graft copolymers were blended with PS to prepare PS/PB‐g‐PS with a rubber content of 20 wt%. The mechanical properties, morphologies of the core‐shell rubber particles and deformation mechanisms under various conditions were investigated. RESULTS: Infrared spectroscopic analysis confirmed that PS could be grafted onto the PB rubber particles. The experimental results showed that a specimen with a ‘cluster’ dispersion state of rubber particles in the PS matrix displayed better mechanical properties. Transmission electron micrographs suggested that crazing only occurred from rubber particles and extended in a bridge‐like manner to neighboring rubber particles parallel to the equatorial plane at a high speed for failure specimens, while the interaction between crazing and shear yielding stabilized the growing crazes at a low speed in tensile tests. CONCLUSION: AIBN can be used as an initiator in the graft polymerization of styrene onto PB. The dispersion of rubber particles in a ‘cluster’ state leads to better impact resistance. The deformation mechanism in impact tests was multi‐crazing, and crazing and shear yielding absorbed the energy in tensile experiments. Copyright © 2009 Society of Chemical Industry     

Poly(styrene‐block‐butadiene‐block‐styrene‐block‐butadiene) and poly(styrene‐block‐butadiene‐block‐methyl methacrylate) copolymers as compatibilizers in PPO–SAN blends. I. Morphology and fracture behavior

The toughness behavior of PPO–SAN blends with the modifier poly(styrene‐block‐butadiene) (SBSB) and with poly(styrene‐block‐butadiene‐block‐methyl methacrylate) copolymers (SBM) under impact loading conditions has been investigated. The observed morphology of blends compatibilized with SBM, in which the rubber phase discontinuously accumulated at the PPO–SAN interface, correlated with about 20 times higher energy dissipation up to maximum force and about seven times higher deformation capacity compared to pure PPO–SAN blends. In contrast, the fracture behavior of the SBSB‐modified blends was not as strongly dependent on the rubber content. It is especially noteworthy that although the SBM modification resulted in a strong increase in toughness of the PPO–SAN blends, no decrease in stiffness could be found with up to 15% rubber additions. The values of Young's moduli remained at the same high level of the nonmodified material. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2037–2045, 2000     

Fracture behavior of styrene‐ethylene‐propylene rubber‐toughened polypropylene

The morphology and fracture behavior of isotactic polypropylene toughened by styrene‐ethylene‐propylene (PP/SEP) were investigated. The SEP rubber, having an average particle size of 0.2 µm, is found to be well dispersed in the PP matrix. The fracture toughness of SEP‐modified PP is greatly improved. The toughening mechanism investigation shows that a widespread crazing zone is generated in the crack tip damage zone. An intense narrow damage band in the center of crazed zone is formed. Crazing and shear yielding are found to be the dominant toughening mechanisms in PP/SEP. The crazes are initiated only by large SEP particles in the blend. The small SEP particles (< 0.3 µm) can neither cavitate nor trigger crazing. As a result, large scale shear deformation is suppressed in this blend. These findings are consistent with the notion that the crack tip plane strain constraint has to be relieved in magnitude in order for the deviatoric stress to reach a critical value for widespread shear banding.     

Tensile behavior of polypropylene blended with bimodal distribution of styrene‐ethylene‐butadiene‐styrene particle size

The objective is to characterize the effects of the bimodal distribution of rubber particles and its blend ratio on the mechanical properties of the thermoplastic polypropylene blended with two different styrene‐ethylene‐butadiene‐styrene triblock copolymer at the intermediate and high strain rates. Tensile tests are conducted at the nominal strain rates from 3 × 10^?1 to 10² (1/s). Phase morphology is investigated to estimate the bimodal rubber particle size distribution. In addition, the in situ observation is conducted during uniaxially stretching within transmission electron microscopy step by step to investigate the deformation events depending on the elongation of samples. The elastic modulus increased gradually as the blend ratio of large rubber particle increased. An increase in the rupture strain and the strain energy up to failure was found for the bimodal rubber particle distributed blend system where the blend ratios of small rubber particle and large rubber particle were same. This is because the smaller particles dominant blend systems show the bandlike craze deformation while the localized plastic deformation is taken place in the larger particles dominated blend systems. The synergistic effect of these rubber particles gives rise to a strong increase in the ductility of these bimodal rubber particle distributed polypropylene systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

EPDM/St‐An graft copolymerization reaction behavior by phase inversion emulsion and the toughness effect of EPDM‐g‐SAN on SAN resin

Styrene‐EPDM‐acrylonitrile tripolymer (EPDM‐g‐SAN) was synthesized by the graft copolymerization of styrene (St) and acrylonitrile (An) onto ethylene‐propylene‐diene terpolymer (EPDM) with “phase inversion” emulsification technique. The high impact strength engineering plastics AES was the blend of SAN resin and EPDM‐g‐SAN, which occupied good weathering and yellow discoloration resistivity. The effects of An percentage in comonomer and the weight proportion of EPDM to St‐An on graft copolymerization behavior and AES notched impact strength were studied. The results showed that monomer conversion ratio (CR) exhibited a peak when the An percentage changed, and the maximum value was 97.5%. Grafting ratio (GR) and grafting efficiency (GE) enhance as well. The notched impact strength of AES presented a peak with the maximum value of 53.0 KJ/m², when An percentage was at the range of 35–40%. The spectra of FTIR showed that St and An were graft onto the EPDM. DSC analysis illuminated that T_g of EPDM phase in the blends was lower than that of the pure EPDM. TEM and SEM micrographs indicated that the polarity of g‐SAN of EPDM‐g‐SAN was the main factor effect the particle morphology, in terms of size, distribution and isotropy. When weight ratio of St to An was 65/35, the polarity of g‐SAN chains was appropriate, and the EPDM‐g‐SAN particles dispersed well in the SAN matrix. The super impact toughness is interpreted in terms of EPDM phase cavitation and enhanced plastic shear yielding. The highest toughness occurs at an optimum EPDM‐g‐SAN phase particle size which is about 0.2 μm in SAN resin matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Application of styrene‐acrylonitrile random copolymer–polyarylate block copolymer as reactive compatibilizer for polyamide and acrylonitrile‐butadiene‐styrene blends

Styrene‐acrylonitrile random copolymer (SAN) and polyarylate (PAr) block copolymer were applied as a reactive compatibilizer for polyamide‐6 (PA‐6)/acrylonitrile‐butadiene‐styrene (ABS) copolymer blends. The SAN–PAr block copolymer was found to be effective for compatibilization of PA‐6/ABS blends. With the addition of 3.0–5.0 wt % SAN–PAr block copolymer, the ABS‐rich phase could be reduced to a smaller size than 1.0 μm in the 70/30 and 50/50 PA‐6/ABS blends, although it was several microns in the uncompatibilized blends. As a result, for the blends compatibilized with 3–5 wt % block copolymer the impact energy absorption reached the super toughness region in the 70/30 and 50/50 PA‐6/ABS compositions. The compatibilization mechanism of PA‐6/ABS by the SAN–PAr block copolymer was investigated by tetrahydrofuran extraction of the SAN–PAr block copolymer/PA‐6 blends and the model reactions between the block copolymer and low molecular weight compounds. The results of these experiments indicated that the SAN–PAr block copolymer reacted with the PA‐6 during the melt mixing process via an in situ transreaction between the ester units in the PAr chain and the terminal amine in the PA‐6. As a result, SAN–PAr/PA‐6 block copolymers were generated during the melt mixing process. The SAN–PAr block copolymer was supposed to compatibilize the PA‐6 and ABS blend by anchoring the PAr/PA‐6 and SAN chains to the PA‐6 and ABS phases, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2300–2313, 2002     

Influence of the rubber crosslinking density of a core–shell structure modifier on the properties of toughened poly(methyl methacrylate)

Four kinds of core–shell structure acrylic impact modifiers (AIMs) with different rubber crosslinking densities were synthesized. The effects of the rubber crosslinking density of the AIMs on the crack initiation and propagation resistance and the mechanical properties of the AIM/poly(methyl methacrylate) (PMMA) blends were investigated, and we found that the maximum stress intensity factor, crack propagation energy, and Izod impact strength reached maximums when the appropriate rubber crosslinking density of AIM, 2.51 × 10²⁵ crosslinks/m³, was adopted. Transmission electron microscopy photographs of the AIM/PMMA blends showed that the AIMs dispersed uniformly in the PMMA matrix. Meanwhile, through the analysis of optical photos and scanning electron microscopy of the impact fracture surface, we found that the deformation mechanism of the AIM/PMMA blends was local matrix shear yielding initiated by rubber particle cavitation of the AIM. The rubber of the AIM, whose crosslinking density was 2.51 × 10²⁵ crosslinks/m³, was beneficial to the formation of intensive voids and initiated the local shear yielding of nearby modifiers of the PMMA matrix effectively in impact tests, which led to higher Izod impact strengths. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of tetramethylpolycarbonate‐block‐poly(styrene‐co‐acrylonitrile) copolymers containing various amounts of acrylonitrile on the interfacial properties of polycarbonate and poly(styrene‐co‐acrylonitrile) blends

Tetramethylpolycarbonate‐block‐poly(styrene‐co‐acrylonitrile) (TMPC‐block‐SAN) block copolymers containing various amounts of acrylonitrile (AN) were examined as compatibilizers for blends of polycarbonate (PC) with poly(styrene‐co‐acrylonitrile) (SAN) copolymers. To explore the effects of block copolymers on the compatibility of PC/SAN blends, the average diameter of the dispersed particles in the blend was measured with an image analyzer, and the interfacial properties of the blends were analyzed with an imbedded fibre retraction technique and an asymmetric double‐cantilever beam fracture test. Reduction in the average diameter of dispersed particles and effective improvement in the interfacial properties was observed by adding TMPC‐block‐SAN copolymers as compatibilizer of PC/SAN blend. TMPC‐block‐SAN copolymer was effective as a compatibilizer when the difference in the AN content of SAN copolymer and that of SAN block in TMPC‐block‐SAN copolymer was less than about 10 wt%. Copyright © 2004 Society of Chemical Industry