Search

Carboxyl-terminated butadiene acrylonitrile liquid rubber toughened silicon carbide and stitched E-glass fibre-reinforced epoxy composite has been fabricated and tested for their relative effect on thermal, wear, visco-elastic and fatigue behaviour. The main objective of this present work is to explicate the importance of rubber toughening on high brittle polymer matrix and the need for secondary strengthening to improve properties. The reinforcements were surface-treated using an amine-functional coupling agent for better adhesion and uniform dispersion on matrix. The composites were made using hand layup method and post cured at 120 °C. The addition of micro rubber into epoxy resin improved the fatigue and visco-elastic properties with a marginal decrement in thermal stability and wear resistance behaviour whereas the addition of silicon carbide significantly improved the properties. A highest fatigue life cycle of 12,941 and storage modulus of 7.8 GPa was observed for composite contains 1 and 10 vol% of silicon carbide and micro rubber, respectively. The initial thermal stability of composite, which contains 2 and 10 vol% of reinforcement measures 348 °C and the lowest coefficient of friction of 0.36 and specific wear rate of 0.028 mm3/Nm. The Scanning electron microscope images illustrate uniform dispersion and improved adhesion of silane surface-modified reinforcements in epoxy matrix. These high toughness polymer composites could be used in high load-bearing engineering applications wherever possible.

In this research, poly(lactic acid) (PLA) was toughened and improved the crystallinity by rubber particles and inorganic filler. CaCO3 was employed as a filler and nucleating agent while poly(methyl methacrylate)-poly(butadiene-styrene) (MBS) core-shell impact modifier was added as a toughening agent. Overall, the enhancements of both the toughness and crystallization of PLA with CaCO3 and MBS were successfully achieved. The tensile modulus and strength of PLA increased with increasing CaCO3 content from 10 to 30wt%. However, they decreased slightly when CaCO3 loading reached 40 wt% due to particles agglomerations. With the addition of MBS rubber, the tensile modulus and strength of the PLA/CaCO3 composites became lower than those observed for PLA/CaCO3 composites due to the softening effect. Furthermore, the compositions with MBS showed superior toughness in terms of the tensile elongation at break and impact strength. CaCO3 nucleated the PLA crystal which reflected as the increase in the degree of crystallinity (Xc) by at least 2 times for all formulations studied. The crystallization half-time (t1/2) of PLA with 40 wt% CaCO3 was dramatically reduced, from 26 min, in neat PLA, to 0.9 min. With the addition of MBS, it did at 2.7 min for the same CaCO3 content. The maximum increment of heat distortion temperature (HDT), around 8 °C, was found for the PLA with 20 wt% CaCO3.

Due primarily to the inherent brittleness of poly(lactic acid) (PLA), numerous studies have sought to improve the mechanical properties (e.g., fracture toughness) of PLA for a wide range of contemporary applications. In this study, we report a facile method by which to prepare esterified poly[styrene-b-(ethylene-alt-propylene)-b-styrene] (eSEPS) as a toughening agent for PLA through the use of thiol–ene click chemistry. The effects of adding 1 to 30 wt % eSEPS on the thermomechanical properties and morphological characteristics of PLA/eSEPS blends have been systematically investigated. Since eSEPS copolymers are more thermodynamically compatible with PLA than their parent partially hydrogenated SIS copolymer, we find a measurable reduction in the thermal properties of PLA from thermal calorimetry and enhanced dispersion of eSEPS within the PLA matrix according to electron microscopy. Considerable boosts in mechanical properties such as toughness (∼60 MJ/m3) and elongation at break (∼470%) are about 16× an...

The toughening mechanisms of poly(lactic acid; PLA) blended with two different elastomers, namely poly (butylene adipate-co-terephtalate; PBAT) and polyolefin elastomers with grafted glycidyl methacrylate (POE-g-GMA), at 10 and 20 wt.%, were investigated. Tensile and Charpy impact tests showed a general improvement in the performance of the PLA. The morphology of the dispersed phases showed that PBAT is in the form of spheres while POE-g-GMA has a dual sphere/fibre morphology. To correlate the micromechanical deformation mechanism with the macroscopical mechanical behaviour, the analysis of the subcritical crack tip damaged zone of double-notched specimens subjected to a four-point bending test (according to the single-edge double-notch four-point bend (SEDN-4PB) technique) was carried out using several microscopic techniques (SEM, polarized TOM and TEM). The damage was mainly generated by shear yielding deformation although voids associated with dilatational bands were observed.

In order to toughen Poly(lactic) acid and binary blends with low PBAT content while maintaining a high biodegradability of the final material, poly(lactic) acid (PLA)/poly(butylene-adipate-co-terephthalate) (PBAT)/ polyolefin elastomer grafted with glycidyl methacrylate (POE-g-GMA) extruded ternary blends have been investigated in this work from a thermal, mechanical, and rheological point of view. The two elastomers have been added in different amounts as dispersed phases into the PLA matrix, paying attention to the final objective: the design of a 90% biodegradable formulation according to EN 13432. These ternary blends exhibited improved impact properties but still low elongation at break. Consequently, to the ternary composition with the best compromise of PLA quantity, biodegradability and thermo-mechanical properties (81 wt.% PLA, 9 wt.% PBAT, and 10 wt.% POE-g-GMA) a small quantity (10 wt.%) of a biobased plasticizer was added in order to further increase the impact properties in parallel with the tensile flexibility. Two types of plasticizers were investigated, one not reactive [Acetyl Tributyl Citrate (ATBC)], and one reactive [Glycidyl ether (EJ-400)]. A micromechanical study, in order to investigate the toughening mechanism of these systems, was carried out on the final formulations. They were also examined by dilatometric tests and elasto-plastic fracture mechanics correlating the data obtained to the morphology and to the rheological properties. In conclusion, the best compromise between impact, tensile properties and biodegradability content was achieved using the reactive plasticizer (EJ-400) whose interaction with the matrix is confirmed by the FT-IR analysis.

This study describes the toughening of poly(lactic acid) (PLA) through blending it with poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers (EPE, Pluronic®) at loadings less than 10 wt%. The miscibility of EPE copolymers in PLA was examined by thermal, morphological, and rheological analysis. Copolymers with low molecular weight and low poly(propylene oxide) (PPO) content were more miscible with PLA but less efficient as a toughening agent. In contrast, copolymers with high PPO content and high molecular weight formed droplets in the PLA and significantly increased the ductility of PLA at 5 wt% loading. More importantly, it was found that the toughening mechanism in those toughened PLA/EPE blends is similar to “rubber toughening of brittle plastics” rather than plasticization. Since the refractive indices of PLA and EPE are nearly matched, the blends were transparent. For the first time, the rheological properties of PLA/EPE blends are studied. Both the miscible and immiscible blends exhibited lower viscosity than neat PLA on account of different mechanisms. The low viscosity of the miscible blends resulted from the plasticization effect of the molecularly dissolved EPEs while the low viscosity of the immiscible blends resulted from the lubrication effect of the phase-separated EPE liquids. This lubrication effect also led to low adhesion on metal surfaces.

In this work, the mechanism behind rubber toughening of poly(lactic acid)/cellulose nanocrystal-g-rubber-g-poly( d -lactide) (CNC-rDx-PDLA) composites was elucidated through systematic study of the effects of rubber segment content (length) in CNC-rDx-PDLA nanofillers and the nanofiller concentrations on the deformation behavior of the nanocomposites. It was shown that with an increase of rubber segment length and rubber filler concentration, the elongation at break of the resulting composites increased. Moreover, a dramatic increase in elongation at break (from 20% to 200%) was observed when the rubber segment content (length) in the CNC-rDx-PDLA nanofillers was increased from 52 to 68%. Cavitation mechanism was found dominant when the rubber segment content in the nanofillers was 52% and below, whereas, stable crazes were formed and followed by fibrillation when the rubber segment content in the nanofillers was increased to 68%, which was evident by small angle X-ray scattering (SAXS) study and scanning electron microscopy (SEM) analysis. The existence of a transition from cavitation to crazing in the composite systems could be attributed to a more mobile rubber phase because of longer rubber chain length. Our study suggests that the effective toughening mechanism for thermoplastics such as PLA is crazing induced plastic deformation.

In recent years, the growing sensibility about environmentally friendly products has pushed the Wood Polymer Composites (WPC) market along an increasing trend. On the other hand, the presence of the wood flour determines a few problems, two of which are particularly significant. First, WPC products are often used in a large range of temperature and moisture conditions that can be demanding for the material. Further, large quantities of wood filler promote the embrittlement of the composite and often cause failure in the finite products. The aim of this work was to evaluate the hygrothermal degradation effects on the tensile properties of a polypropylene based WPC toughened with a thermoplastic elastomer. Santoprene improves the elongation at break, as revealed by tensile tests, but increases porosity, as shown by SEM analysis. In wet conditions, the presence of the thermoplastic elastomer reduces the negative effect of the hygrothermal degradation. For these reasons, the addition of Santoprene is suggested only for applications in humid environment.

The present work fits into the stream of study and analysis of biobased and/or biodegradable materials, considering the need to improve their properties from a technological point of view to allow their wider use in final products. In this paper a blend of an extrusion grade poly(lactic acid) (PLA) and a percentage of a particular type of high molecular weight poly(butylene adipate-co-terephathalate) (PBAT) was investigated. The blend was such that the PBAT resulted in a dispersed phase in the PLA matrix. Tensile properties, Charpy impact strength, energy absorbed by the sample during three-point bending tests, melt flow index, fracture behavior and morphology were determined to characterize PLA/PBAT blends with the aim of correlating the composition to processability and final properties. Furthermore, analytical models were applied to check if variations of the mechanical properties with an increase of the rubber content were in agreement with existing predictive theories. To evaluate the fracture behavior, starting from the Load Separation Criterion, “material key curves” of the materials, a support for a comparative study (macroscopic scale) of the plastic deformational mechanisms involved in the fracture process was achieved. The influence of the deformation rate and the temperature on the toughness of the PLA/PBAT was investigated. In particular, the ductile-to-brittle transition temperature, at a fixed test speed was estimated and a theoretical model, which is useful to predict the absorbed energy by varying the deformation rate, was proposed. This last model was validated by comparing the resulting analytical equation with the experimental data obtained through three-point bending and impact tests at different velocities.

The compatibilization of a virgin polyethylene terephthalate/polyethylene (PET/PE) blend and a recycled multilayered post-industrial food tray of similar composition are investigated. The compatibilizers of focus are a propylene ethylene rubber (PER) and a styrene ethylene / butylene styrene triblock copolymer grafted with maleic anhydride (SEBS-g-MA). This work examines the effect of these compatibilizers on both the mechanical properties (impact and tensile properties) and morphology of the virgin blends and verifies whether these effects are transferable to an actual waste stream of post-industrial food trays with comparable composition. Regarding the virgin blends, it was concluded that both compatibilizers increase the impact strength and elongation at break of the material, wherein PER increases the impact strength more effectively than SEBS-g-MA. Moreover, PER succeeds in maintaining both tensile strength and stiffness of the blends. Also, the morphology of the PER blends shows clear indication of rubber toughening. The results of the virgin blends are to a certain extent transferable to an actual waste stream consisting of post-industrial food trays with comparable composition. PER shows to be the most promising candidate for increasing toughness while maintaining stiffness and tensile strength.

Friedel-Crafts alkylation reaction was employed to reactively compatibilize the polypropylene (PP)/acrylonitrile- butadiene-styrene (ABS) blends, using AlCl3 as a catalyst. Rheology, morphology and mechanical properties of the reactive compatibilized blends along with the reference un-compatibilized samples were studied. Scanning electron microscopy (SEM) observations showed that blends containing catalyst exhibited an improvement in the dispersion state of ABS rubber particles. The results of mechanical tests revealed that reactive compatibilization partly increased the ultimate strength and Izod impact strength of the blends with a loss in tensile ductility. The change in these properties was explained in terms of different chemical reactions including grafting and degradation. Occurrence of these reactions was confirmed using different viscoelastic properties of the compatibilized blend samples. A great improvement in ultimate strength and impact toughness to levels much higher than those of neat PP was achieved in reactively compatibilized PP/ABS blends containing PP-g-MA. These findings were justified by morphological and rheological analyses. The formation of graft copolymer was also confirmed using Fourier transform infrared spectroscopy (FTIR) measurements. The results of impact toughness data were in agreement with the interfacial tension values measured via contact angle analysis. The deformation behavior of the different compatibilized samples was rationalized via fractographic study of the impact-fractured surfaces.

While vinyl-terminated butadiene acrylonitrile is frequently used for the toughening of vinylester and polyester, very limited research has been conducted on modification of epoxy with this oligomer. Herein, the effect of vinyl-terminated butadiene acrylonitrile addition to epoxy in bulk and glass reinforced composite is systematically investigated. Thermo-physical behavior and mechanical characteristics of the samples are determined. To interpret the test results, the void content of reinforced samples is measured and fracture surface of the specimens is investigated. It is found that vinyl-terminated butadiene acrylonitrile improves the toughness with slight negligible effects on other characteristics. Incorporation of 15 phr of vinyl-terminated butadiene acrylonitrile increases the KIC of epoxy from 0.6 MPa to 2.3 MPam0.5. Similarly, addition of 15 phr vinyl-terminated butadiene acrylonitrile leads to 67% enhancement in the interlaminar fracture toughness of composites. The toughening mechanism...

The recent advances and theories in the studies of the toughening mechanism have been reviewed to explain the effect of rubber particles in different rubber modified Polyolefin materials. To elucidate toughening effect, major theories e.g., critical particle distance, particle size, micro deformation by stress field of rubber, shear yielding and crazing phenomena has been reviewed. Based on these theories, variety of blends of rubber modified Polyolefin materials has been compared but no one of these provided adequate information to be considered as total theory of toughening. To achieve the objective of toughening, it is important to maintain critical particle size, uniform particle distribution and good interfacial adhesion by inclusion of suitable compatibilizer in the matrix. Particular attention has been paid to study the type of morphology and bimodal distribution of rubber particles to elucidated toughening effect. Rubber particle cavitation, which comes from micro-voids and rubber phase interface ...

Glycolyzed polylactic acid (GPLA)-cured epoxidized natural rubber (ENR) is developed for use as a toughening agent for PLA resin. GPLA is obtained from chemical recycling of PLA resin by a glycolysis reaction. GPLA-cured ENR is then prepared by the crosslinking reaction of ENR with GPLA in an internal mixer. Chemical structures of the cured products are characterized by solvent fractionation and thermogravimetric analysis (TGA). The cured ENR products are blended with PLA resin, by varying the cured ENR contents from 5 to 15% wt. Mechanical properties of the blends, and their toughening mechanisms are examined. The cured ENR materials has higher efficiency in improving toughness of PLA resin, compared to uncured ENR, likely due to their rubbery network nature and higher compatibility with the PLA matrix. The incorporation of 5% wt. GPLA-cured ENR also improves elongation at break with no adverse effect on tensile strength and modulus of PLA.

In this paper, we have explored the potential of core–shell poly(siloxane)-epoxy microspheres towards improving the dynamic properties of a conventional unsaturated polyester (USP). Micro-sized poly(siloxane) beads were prepared by suspension polymerisation route, where the particle dimensions could be tailored by varying the operating parameters, particularly stirring speed and feed concentration. The core was subsequently coated with epoxy to form an external layer compatible with the USP resin, with an aim to aid its homogeneous dispersion in the thermosetting resin. Toughened USP composites containing varying amounts of both coated and uncoated microspheres (3–10 % w/w) were prepared by curing under ambient conditions, and their mechanical properties were evaluated under both quasi-static and dynamic loading conditions. The introduction of epoxy-coated poly(siloxane) led to a proportional decrease in the tensile strength and modulus, which were found to compare well with the predictions based on Halpin–Tsai and Lewis–Nielson empirical models. Significant improvements in the impact strength of USP could be achieved, and under optimised conditions, 101 % increase in the impact strength was observed, which corroborated with significant increase in mean critical stress intensity factor (76 %). Morphological investigations of the fractured surface revealed the presence of characteristic features which were used to establish the underlying routes responsible for the toughened nature of the USP composites.

Maleation of ethylene–octene copolymer (EOC) with incorporation of styrene as a comonomer was investigated. Maleated EOC thus obtained was compounded with polyamide-6 (PA6) and its efficiency as an elastomer in PA6 matrix was evaluated. Maleated EOC incorporated with styrene provides higher impact strength than the conventional maleated EOC. By various investigations, it was proved that the incorporation of the styrene increases the graft degree of MA onto EOC and the maleated EOC thus obtained shows higher performance as an elastomer in the rubber toughening of PA6 due to enhanced interfacial strength and stability.

This work aimed at investigating the thermal mechanical behavior of recycled polypropylene (PP)-based composites under dynamic loading. PP was blended by extrusion with different fractions of ethylene octene copolymer (EOC) as soft rubber toughening agent and talc as rigid reinforcing agent. To simulate mechanical recycling, the composites were grinded and re-extruded up to 6 times. The dynamic behavior was studied by means of a split Hopkinson pressure bar at various strain rates and temperatures. We found that neat PP and PP/talc composites presented a brittle behavior at low temperatures. The addition of EOC inclusions markedly improved the impact resistance of PP and PP/talc. The results also indicated that the impact resistance of PP/talc was improved with the recycling numbers due to a fragmentation of the talc particles during the reprocessing inducing a self-reinforcement. However, the impact resistance of PP/EOC decreased with the recycling due to chain scission mechanisms. Concerning PP/EOC/talc composite, its dynamic behavior was almost constant with the recycling number possibly induced by equilibrium between self-reinforcement and chain scission mechanisms. Complementary information about the dynamic behavior of the materials was deduced from optical microscopy investigation of the morphology after dynamic compression testing.

The objective of this work was to study the compatibilizer effect on polypropylene (PP) and acrylonitrile butadiene styrene (ABS) blends. The blends were coextruded and injection molded in various ratios of ABS with and without compatibilizers. Universal testing machine was employed to analyze the tensile properties of basic PP/ABS binary blends. From the mechanical testing, the impact and tensile properties of PP/ABS blend were optimized at 80/20 weight ratio. Various compatibilizers such as PP-g-MAH, SEBS-g-MAH and ethylene α-olefin copolymer were used and their comparative performance on binary blend was enumerated. Hybrid compatibilization effect was also studied and reported. However, the addition of compatibilizers showed the maximum increase in impact strength attributed to rubber toughening effect of ABS. The effect of compatibilizers on morphological properties was examined using scanning electron microscopy (SEM). SEM micrographs depicted the more efficient dispersion of ABS particles in PP matrix with the addition of compatibilizers. Further, interparticle distance analysis was carried out to evaluate the rubber toughening effect. The ABS droplet size in compatibilized PP/ABS blend was brought to minimum of 3.2 μm from 9.9 μm with the addition of compatibilizers. The melt rheology of PP/ABS blend systems was investigated through parallel plate arrangement in frequency sweep. Linear viscoelastic properties like storage (G′) and loss (G″) modulus and complex viscosity (η*) have been reported with reference to the virgin materials. It is understood that the combination of compatibilizers (hybrid compatibilizer) had a considerable effect on the overall blend properties.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bio-based and biodegradable thermoplastic with restricted industrial applications due to its brittleness and poor processability. Natural rubber (NR) has been used as a toughening agent, but further physical improvements are desired. In this study, rubber toughening efficiency was significantly improved through the synergistic use of a trifunctional acrylic coagent and an organic peroxide during reactive extrusion of PHBV and NR. The rheological, crystallization, thermal, morphological, and mechanical properties of PHBV/NR blends with 15% rubber loading were characterized. The peroxide and coagent synergistically crosslinked the rubber phase and grafted PHBV onto rubber backbones, leading to enhanced rubber modulus and cohesive strength as well as improved PHBV&ndash, rubber compatibility and blend homogeneity. Simultaneously, the peroxide&ndash, coagent treatment decreased PHBV crystallinity and crystal size and depressed peroxy-radical-caused PHBV degradation. The new PHBV/NR blends had a broader processing window, 75% better toughness (based on the notched impact strength data), and 100% better ductility (based on the tensile elongation data) than pristine PHBV. This new rubber-toughened PHBV material has balanced mechanical performance comparable to that of conventional thermoplastics and is suitable for a wide range of plastic applications.

A series of dynamically vulcanized isotactic polypropylene (PP)/ethylene–propylene–diene rubber thermoplastic vulcanizates (TPVs) containing different content of β-nucleating agent (β-NA) were prepared and introduced into isotactic PP matrix as a toughening agent. The effect of β-nucleated TPVs (β-TPVs) on the toughness and other properties of PP were studied. Differential scanning calorimetry and wide-angle X-ray diffraction results indicated that the β-crystallinity and the relative content of β-phase in β-TPVs samples and the toughened blends increased with the content of β-NA increasing. The notched impact strength of PP toughened by β-TPVs, with limited loss in the tensile strength and rigidity, showed an almost linear increase with increasing β-NA content. Especially when the content of β-NA was 0.5 wt%, the impact strength of the toughened blends was ten times more than that of pure PP. The toughening mechanism based on classical rubber toughening mechanisms was discussed and a synergic toughening mechanism was proposed.

A method used to determine whether plastics should be described as high-temperature thermoplastics, that is, those capable of being used at ≥150 °C, based on values of heat distortion temperature and continuous use temperature, has been proposed. These all have substantially aromatic structures and high-temperature properties, as well as generally having good oxidation resistance, good mechanical properties, good chemical resistance, and usually good fire retardancy. It has been shown that polyphthalamides hold an intermediate position between conventional engineering thermoplastics, and the high-temperature group. This group of polymers is the most expensive plastics material, so are used in niche applications where their excellent performance is required. Monomer production, and the production, structure, properties, processing, and applications of six groups of high-temperature thermoplastics are discussed. These are polysulfones, polyphenylene sulfides, imide polymers, polyaryletherketones, polybenzimidazole, and liquid-crystal polymers. Commercial examples of these plastics are included.

Poly (lactic acid) (PLA) was melt blended in a twin screw extruder using an ethylene-methyl acrylate-glycidyl methacrylate rubber as a toughener. PLA/rubber blends were immiscible as observed by scanning electron microscopy. Impact strength and ductility of PLA were improved by the addition of the rubber at the expense of strength and stiffness. An organo-montmorillonite (OMMT) was used at 2 wt % to counteract the negative effect of the rubber on modulus, and balanced properties were observed at 10 wt % rubber content. X-ray diffraction and transmission electron microscopy revealed the formation of intercalated/exfoliated structure in the ternary nanocomposites. Thermal behavior analysis indicated that the degree of crystallinity is slightly affected by the clay and the rubber. Both the clay and the rubber decreased the crystallization temperature of PLA and acted as nucleating agents for PLA. The viscosity of the mixtures as measured by melt flow index was highly influenced by the rubber and the OMMT. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of loading rate on toughness characteristics of hybrid rubber-modified epoxy was investigated. Epoxy was modified by amine-terminated butadiene acrylonitrile (ATBN) and recycled tire. Samples were tested at various loading rates of 1–1000 mm/min. Fracture toughness measurements revealed synergistic toughening in hybrid system at low loading rates (1–10 mm/min); hybrid system exhibited higher fracture toughness value in comparison with the ATBN-modified resin with same modifier content. However, synergistic toughening was eliminated by increasing the loading rate. At higher loading rates (10–1000), the fracture toughness of hybrid system decreased gradually to the level lower than that of ATBN-modified epoxy. Fractography of the damage zones showed the toughening mechanisms of ATBN-modified system was less affected by increasing the loading rate compared to that of hybrid system. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The present research aims to utilize ultrafine elastomeric particles to reduce the problem of brittleness in poly(lactic acid) (PLA). Particles of acrylate rubber were added to PLA at the range from 0.1 to 10 wt%. Maximum reduction of the flexural modulus and the tensile modulus was achieved by 20 and 45% respectively when the acrylate rubber was applied at 10 wt%. The tensile elongation at break of the rubber-modified PLA was also raised around 50 times from the 3.5% observed in the neat PLA to 200%. The toughening efficiency of the ultrafine rubber particles was also reflected through the significant increase in the impact strength by fourfolds. Fractographs of the acrylate rubber-modified PLA verified plastic deformation and good dispersion of the rubber particles in the PLA. Microscopic observation revealed that the ultrafine acrylate rubber played an important role inducing numerous crazes as the mechanism for energy absorption. The introduction of the ultrafine acrylate rubber particles by only 0.5 wt% helped increasing the degree of crystallinity.

Poly(butyl acrylate) was prepared by the free radical polymerization of butyl acrylate as an initiator in the presence of 2,2′-Azoisobu-tyronitrile (AIBN) and the average molecular weight, polydispersity and thermal stability were evaluated. PLA and PBA were melt blended using a Haake Rheometer, and the light transmission, thermal properties, dynamic rheological properties, mechanical properties, phase morphology of blends and toughening mechanism were investigated. Dynamic rheology, SEM and DSC results show that the PLA is partial miscible with PBA. The PBA component improved the crystallization ability of PLA and the crystallinity of PLA increased with content of PBA (

Rubber toughening of poly(ether imide) (PEI) has been elusive up to now due to the high processing temperature of PEI, which leads to degradation of the rubber. In this study, by profiting from the miscibility between PEI and poly(butylene terephthalate) (PBT), and the low T g of PBT, we prepared a blend by melt extrusion with 20 wt% PBT in an attempt to render it toughenable by decreasing its T g and processing temperature. The PEI-rich blend was subsequently mixed with maleic anhydride (0.9 wt%) grafted poly(ethylene-octene) copolymer (mPEO) up to 30 wt%. The decrease in T g and processing temperature resulted in no observable degradation of the mPEO, and to the formation of a homogeneous morphology of rubber particles with a fine particle size, indicating that compatibilization was achieved. Upon rubber addition, stiffness decreased, while a very large toughness increase occurred with only 15% mPEO (impact strength more than 10-fold that of the PEI–PBT matrix). Upon observation of the fracture surface, the increase in impact strength was attributed partially to the cavitation and debonding of the rubber particles, and mostly to the deformation and yielding of the PEI–PBT matrix.

This paper focuses on the use of epoxidized natural rubber (ENR) as a toughening agent for nylon 6 (PA6). Natural rubber (NR) was used to compare with ENR. Polymer blends were prepared by using a twin-screw extruder and pressing as a sheet in a compression molding machine. It was found that NR and ENR decreased yield stress and tensile strength but slightly increased elongation at break of PA6. NR slightly decreased impact strength of PA6, whereas this property increased up to sixfold by blending with ENR. This phenomenon could be explained in terms of blend morphology. Too large a particle diameter of NR was a cause of the premature failure. The impact strength of the blends increased with increasing ENR content. Rubber particle diameter also increased but was still much smaller than natural rubber particles. Phenolic resin was employed for crosslinking ENR. Compounded ENR increased tensile properties but decreased impact strength of the blends. This was because the morphology of ENR was changed from small particles to large patches of rubber after vulcanization.

The effect of adding rubber on the properties of glass-fibre-filled nylon 66 was investigated in this study. Styrene-Ethylene-Butylene-Styrene and Ethylene-Propylene elastomers grafted with maleic anhydride (SEBS-g-MA and EP-g-MA, respectively) were used to toughen the nylon-matrix composites. Impact strength and elongation at break were found to increase with increasing rubber content, but flexural strength, tensile strength and stiffness decreased; however, by adding moderate amounts of rubber to glass-fibre-reinforced nylon 66, a desirable balance between stiffness and toughness of the material may be obtained. For example, the addition of 10 wt.% of SEBS-g-MA to nylon 66 with 23.62 wt.% glass fibre loading resulted in 28.3% and 167% increase in tensile strength and impact strength of the composites, respectively, when compared to neat nylon 66. This suggests that combining both glass fibres and rubber with nylon 66 is a useful strategy to optimize and enhance the properties of nylon 66. The procedure may be used to recycle polyamides, in general, and to develop components for under-the-hood automotive applications, in particular. On a etudie dans ce travail l'effet de l'ajout de caoutchouc sur les proprietes du nylon 66 renforce de fibre de verre. On a utilise des elastomeres de styrene-ethylene-butylene-styrene et d'ethylene-propylene greffe avec de l'anhydride maleique (SEBS-g-MA et EP-g-MA, respectivement) pour renforcer les composites a matrice de nylon. On a trouve que la force d'impact et l'elongation a la cassure augmentaient avec l'augmentation de la teneur en caoutchouc, mais que la force de flexure, la force extensible et la rigidite diminuaient; toutefois, en ajoutant des quantites moderees de caoutchouc au nylon 66 renforce en fibre de verre, un equilibre souhaitable entre la rigidite et la durete du materiau peut etre obtenu. Par exemple, l'ajout de 10 % en poids de SEBS-g-MA au nylon 66 avec un chargement de 23,62 % de fibre de verre mene a une augmentation de 28,3 % et 167 % de la force extensible et de la force d'impact des composites, respectivement, comparativement au nylon 66 pur. Cela suggere que l'association de fibre de verre et de caoutchouc a du nylon 66 est une strategie utile pour optimiser et accroitre les proprietes du nylon 66. La technique peut etre utilisee pour recycler des polyamides en general, et pour mettre au point des pieces de mecanique automobile en particulier.

PurposeThe purpose of this paper is to evaluate the mechanical properties of glass fibre reinforced epoxy composites modified with amine‐terminated poly (ethylene glycol) benzoate (ATPEGB) along with their thermal stability.Design/methodology/approachATPEGB prepared from poly (ethylene glycol) (PEG) of different molecular weights (200, 400, 600, 4,000 and 20,000) were used as modifiers for glass fibre epoxy composite here. For toughening, 12.5 parts per hundred grams (phr) of epoxy resin of each ATPEGB was added to epoxy and pre‐reacted with it. The impact, tensile and flexural strengths of modified and unmodified composite were characterised and compared for each ATPEGB.FindingsModified resin displayed a significant improvement in fracture toughness with glass fibre over unmodified epoxy. The modification caused the formation of oligomer domains having relatively round shapes in the matrix. These oligomer domains led to improved strength and toughness due mainly to the “rubber toughening” effect in the brittle epoxy matrix. The optimum results were obtained for composite modified with ATPEGB‐2 prepared from PEG of molecular weight 400.Research limitations/implicationsIn the present context, only 12.5 phr concentration of each ATPEGB was used to modify composite and the composites were made sing three layers of glass fibre. Besides, modification could also be done using other concentrations and more layers of glass fibre could also be used to make composite.Originality/valueThe method for enhancing toughness of epoxy glass fibre composite was novel and finds numerous applications as surface coatings, casting and adhesive onto an intricate structure, etc.

Polystyrene (PS), being an amorphous polymer is immiscible with other polymers. To engender miscible blends, PS has been functionalized with an active amino-functional group on the molecular chains of PS to yield amino-substituted polystyrene (APS), which serves as a reactive compatibilizer. The compatibilization effect of amino functionalized polystyrene on the rubber toughening was explored and results were compared in terms of morphology, thermal, and mechanical properties of PS/SEBS-g-MA versus APS/SEBS-g-MA blends. In addition, the effect of rubber content on the blend morphology and mechanical properties were investigated. An appreciable change in the thermal stability of APS blends in comparison with PS blend has been probed. A marked correlation has been observed between phase morphology and thermal stability. Use of APS produced the compatibilized blends which render improved blend morphology, enhanced thermal and mechanical properties. Optimal thermal, morphological and mechanical profiles were depicted by 20-wt% APS blend.

The aim of this study was to investigate influences of three different ethylene copolymers on the toughness and other properties of very brittle biopolymer PLA (polylactide). For this aim, PLA was melt blended by twin-screw extruder with various amounts of ethylene vinyl acetate (EVA), ethylene-methyl-acrylate (EMA) and ethylene-n-butyl acrylate-glycidyl-methacrylate (EBA-GMA). SEM and DSC analyses indicated that these ethylene copolymers were thermodynamically immiscible with phase separation in the form of 1-5 mu m sized round domains in the PLA matrix. Rubber toughening mechanisms of EVA, EMA and EBA-GMA were very effective to improve ductility and toughness of PLA significantly. Depending on the type and content of the ethylene copolymers, the highest increases in % elongation at break, Charpy impact toughness and G(IC) fracture toughness values of PLA were as much as 160, 320 and 158%, respectively. Although there were no detrimental effects of using EVA, EMA and EBA-GMA on the thermal properties of PLA, they resulted in certain level of reductions in stiffness, strength and hardness values.

Composite material has attracted increasingly remarked interest over the last few decades and set it apart in its own class due to its distinct properties. This paper is a review on the matrix toughness of thermoplastic polymer composites. Toughness of thermoplastics has been actively studied since the 1980s.the main advantage in using thermoplastics to toughen resins is that their incorporation need not result in important decreases in desirable properties such as modules and yield strengths. However, the predominant criteria for achieving optimum toughness enhancement in the thermoplastic toughening of epoxy resins are still not all that clear from the literature. Epoxy and polyester resins are commonly modified by introducing carboxyl-terminated butadiene-acrylonitrile copolymers (ctbn). A tough elastomeric phase, for example, a silicone rubber with good thermal resistance in a polyimide resin, produced a tough matrix material. It summarizes what the authors believe are the important requirements for good thermoplastic toughening.

Core-shell polybutadiene-graft-polystyrene (PB-g-PS) rubber particles with different ratios of polybutadiene to polystyrene were prepared by emulsion polymerization through grafting styrene onto polybutadiene latex. The weight ratio of polybutadiene to polystyrene ranged from 50/50 to 90/10. These core-shell rubber particles were then blended with polystyrene to prepare PS/PB-g-PS blends with a constant rubber content of 20 wt%. PB-g-PS particles with a lower PB/PS ratio (

When compounding engineering thermoplastics with glass fibers for reinforcement purposes, a tremendous amount of polymer-containing waste is generated. However, the polymer of interest is usually commingled with the polymer used to purge the extruder. Reclaiming valuable polymer from this waste is hindered by the incompatibility with the purging material since this leads to a blend system that has poor mechanical properties and low economic value. For this reason, this potentially valuable post-industrial polymer-waste is normally land filled. The current research is directed at the characterization and reuse of a post-industrial PA66 filled with glass fibers; this was separated from LDPE purge material and its impact resistance was modified through rubber toughening. Styrene-Ethylene-Butylene-Styrene and Ethylene-Propylene elastomers grafted with maleic anhydride (SEBS-g-MA and EP-g-MA respectively) were used as the toughening agents in this study due to their compatibility with PA. Izod impact strength, tensile strength and modulus, flexural strength, and elongation at break were used to characterize mechanical properties of the rubber-toughened recycled glass-filled PA66. The morphology of the fracture surfaces of the composites was examined by Scanning Electron Microscopy (SEM). It was found that both impact strength and elongation at break increase with increasing rubber content while flexural strength and tensile strength suffer upon incorporating rubber; however, by adding moderate amounts of rubber to the recycled glass-fiber-reinforced PA66 a balance between stiffness and toughness of the material could be obtained. For example, the addition of 10 wt.% of SEBS-g-MA to the recycled PA66 with 23.62 wt.% glass fiber loading resulted in a 27% and 151% increase in tensile strength and impact strength respectively of the blends when compared with neat PA66. This suggests that compounding both glass fibers and elastomers with PA66 is a useful strategy to recycle PA66, especially for reuse in under-the-hood automotive applications.

The aim of this study was to investigate rubber toughening of resol type phenol–formaldehyde resin. For this purpose, phenolic resin was first modified by acrylonitrile butadiene rubber alone, and then by using nitrile rubber together with 3-aminopropyltriethoxysilane. Test specimens were prepared by mixing and casting of liquid phenolic resin in three groups. In the first one, neat phenolic resin specimens were produced. In the second group, phenolic resin was modified with 0.5, 1, 2, and 3 wt% nitrile rubber, while in the last group modification was carried out by using 0.5 wt% nitrile rubber together with 1, 2, and 4 wt% amino silane (with respect to nitrile rubber). All specimens were heat cured in an oven. In order to observe behavior of the specimens, three-point bending, Charpy impact, plane-strain fracture toughness, and dynamic mechanical analysis tests were conducted according to the related ISO standards for all specimen groups. Scanning electron microscopy (SEM) was also used for the fractographic analysis of some samples. It was concluded that although there were problems in mixing and casting of liquid resol type phenolic resin, its toughness could be improved by using nitrile rubber and amino silane. Modification by using nitrile rubber and amino silane together was much more effective than by using only nitrile rubber. For instance, in this synergistic case Charpy impact strength and fracture toughness values of the neat phenolic specimens were increased 63 and 50%, respectively. SEM studies indicated that the main rubber toughening mechanism was shear yielding observed as deformation lines, especially initiated at the domains of nitrile rubber and amino silane.

The rubber toughening of nylon 6 nanocomposites prepared from an organoclay was examined as a means of balancing stiffness/strength versus toughness/ductility. Nine different formulations varying in montmorillonite, or MMT, and maleated ethylene/propylene rubber or EPR-g-MA rubber content were made by mixing of nylon 6 and organoclay in a twin screw extruder and then blending the nanocomposites with the rubber in a single screw extruder. In this sequence, the MMT platelets were efficiently dispersed in the nylon 6 matrix. The MMT platelets did not penetrate into the rubber phase. The addition of clay affected the dispersion of the rubber phase resulting in larger and more elongated rubber particles. The tensile properties and impact strength of these toughened nanocomposites are discussed in terms of the MMT and rubber contents and morphology. There is a clear trade-off between stiffness/strength versus toughness/ductility.

Ethylene-octene random copolymer (EOC) is one of the most commonly employed elastomers for PP, and as such its rubber toughening efficiency has been extensively studied. However, most existing studies employ EOC containing an octene comonomer of about 8 mol %. Therefore, in this study, we investigated the effect of EOC octene comonomer content on the morphology and thermal and mechanical properties of PP-ethylene random copolymer (PP-CP)/EOC (80/20 wt %/wt %) blends. It was clearly shown that the properties of the blends are significantly affected by the octene content. The rubber particle size of the blends decreased as the octene content in the EOC was increased, which was a consequence of the reduced interfacial tension between PP-CP and EOC. Impact strength of the blends as a function of octene content displayed a brittle-ductile transition. The tensile yield strength and modulus of the PP-CP/EOC blends were decreased by addition of EOC, owing to incorporation of the soft EOC into the hard PP-CP. The tensile yield strength and modulus of PP-CP/EOC blends decreased monotonically with the octene content in the EOC. The melting temperature as well as the crystallinity of the PP-CP phase were not affected significantly by the addition of EOC whereas a notable shift in melting and crystallization temperatures was observed for the EOC phase. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1133–1139, 2007

In the present study two series of isotactic polypropylene (iPP)/SiO2 nanocomposites containing 1, 2.5, 5, 7.5, and 10 wt % SiO2 nanoparticles were prepared by melt-mixing on a twin-screw corotating extruder. In the first series untreated fumed silica nanoparticles were used, whereas in the second nanoparticles were surface-treated with dimethyldichlorosilane. In both cases, the average size of the primary nanoparticles was 12 nm. Tensile and impact strength were found to increase and to be affected mainly by the type and content of silica nanoparticles. A maximum was observed, corresponding to samples containing 2.5 wt % SiO2. These findings are discussed in light of the SEM and TEM observations. By increasing the amount of nanoparticles, large aggregates of fumed silica could be formed, which may explain the reduction of mechanical properties with higher concentrations of SiO2. However, it was found that surface-treated nanoparticles produced larger aggregates than did those derived from untreated nanoparticles, despite the increased adhesion of the iPP matrix, as was postulated from yield strength. This behavior negatively affected mechanical properties. In addition, an effort was made to determine if toughening theories, mainly the critical interparticle distance for rubber toughening or composites, also might be applicable in nanocomposites. From DSC measurements it was demonstrated that silica nanoparticles acted as effective nucleating agents, increasing the crystallization rate and the degree of crystallinity of iPP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2684–2696, 2006

A common method for toughening thermoset resins is the addition of butadiene-acrylonitrile based rubber modifiers. A difficulty experienced by diglycidyl ether of bisphenol-A (DGEBA) vinyl esters (VE) compared to other thermosets is the solubility of the butadiene-acrylonitrile modifier. In this study, a miscible system was prepared by reducing the VE monomer molecular weight to 540 g/mol from industrially used monomers possessing molecular weights greater than 700 g/mol. A main objective of this study was to toughen the vinyl ester while limiting plasticization by varying rubber reactivity and concentration. All modified samples experienced a significant increase in fracture toughness with some degree of plasticization, as shown by losses in modulus and glass transition temperature ( T g ). Epoxy terminated rubber (ETBN) yielded a higher toughness than vinyl terminated rubber (VTBN) due to the difference in rubber particle formation and resulting morphology. Chemical linkage of VTBN to the vinyl ester matrix hindered complete phase separation, but helped the retention of mechanical properties when compared to ETBN.

Styrenic polymers and copolymers are often impact modified with rubber particles. The efficiency of rubber toughening depends mainly on the size of the rubber particles and the degree of cross-linking. The deformation rate, the temperature, the orientation of the polymer molecules and the efficiency of rubber grafting also influence rubber toughening. It is thought that on impact, cavitation inside the rubber particles occurs which reduces the detrimental dilatational stress in the bulk polymer without forming cracks in the brittle matrix or at the rubber-matrix interface. Crazing and shearing are facilitated if the rubber particles can easily cavitate. This can be achieved by either avoiding too much cross-linking or by adding oil (silicone oil in the case of ABS) into the rubber particles, which acts as nuclei for void formation. An electron spectroscopic imaging method is described which allows visualizing the location of the oil. Already after cooling silicone oil modified ABS samples down to liquid nitrogen temperature rubber cavitation is observed. This cavitation is caused by the thermal stress developing due to the differences in thermal expansion coefficient between the rubber phase and the SAN-matrix and is facilitated by silicone oil. Voiding also leads to an increase of light scattering, which can be detected by an optical microscope using dark field illumination.

The fracture behaviors of α-zirconium phosphate (α-ZrP) based epoxy nanocomposites, with and without core-shell rubber (CSR) toughening, were investigated. The state of exfoliation and dispersion of α-ZrP nanofiller in epoxy were characterized using X-ray scattering and various microscopy tools. The level of enhancement in storage moduli of epoxy nanocomposite against neat epoxy is found to depend on the state of exfoliation of α-ZrP as well as the damping characteristics of the epoxy matrix. The fracture process in epoxy nanocomposite is dominated by preferred crack propagation along the weak intercalated α-ZrP interfaces, and the presence of α-ZrP does not alter the fracture toughness of the epoxy matrix. However, the toughening using CSR can significantly improve the fracture toughness of the nanocomposite. The fracture mechanisms responsible for such a toughening effect in CSR-toughened epoxy nanocomposite are rubber particle cavitation, followed by shear banding of epoxy matrix. The ductility and toughenability of epoxy do not appear to be affected by the incorporation of α-ZrP. Approaches for producing toughened high performance polymer nanocomposites are discussed.

Rubber toughening of an amorphous polyamide (Zytel 330) using combinations of triblock copolymers of the type SEBS and a maleic anhydride functionalized version, SEBS-g-MA, was investigated and the results compared with those of nylon 6 and nylon 66. The effects of rubber content and the type of extruder on the morphology, Izod impact behavior and the ductile–brittle transition temperature were explored. The shape and sizes of the rubber particles in blends with this amorphous polyamide were found to be more similar to those in nylon 6 than in nylon 66 blends. The twin screw extruder produced smaller particles with a more narrow distribution of sizes than the single screw extruder. Higher rubber contents generally yielded tougher blends; there is a critical rubber particle size above which the ternary blends are brittle at 20 wt% total rubber. The ductile-to-brittle temperature was found to decrease with increased rubber content and decreased rubber particle size. In general, the trends for this amorphous polyamide are rather similar to those reported earlier for semi-crystalline nylon 6 and nylon 66.

Tensile tests on high-impact polystyrene (HIPS) show that a 60 Mrad dose of γ-radiation raises the yield stress from 11.5 to 19.8 MPa, and the flow stress from 10.0 to 19.6 MPa, while reducing the elongation at break from 50 to 4%. Similar reductions in fracture resistance are observed in irradiated Charpy impact specimens. The Tg of the rubber phase shifts from −70 to −57 °C, and its estimated shear modulus increases from 0.1 to 0.5 MPa. It is concluded that the observed changes in mechanical properties are due almost entirely to crosslinking of the polybutadiene. This not only inhibits cavitation and fibrillation in the rubbery membranes of the “salami” particles, thereby delaying yield, but also makes the fibrillated membranes more resistant to further dilatation, so that rates of craze thickening in the polystyrene matrix are reduced. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2168–2180, 2004

In this study, improvements in mechanical and thermal behavior of short glass fiber (GF) reinforced diglycidyl ether of bisphenol-A (DGEBA) based epoxy with hydroxyl terminated polybutadiene (HTPB) modification have been studied. A silane coupling agent (SCA) with a rubber reactive group was also used to improve the interfacial adhesion between glass fibers and an epoxy matrix. 10, 20, and 30 wt% GF reinforced composite specimens were prepared with and without silane coupling agent treatment of fibers and also HTPB modification of epoxy mixture. In the ruber modified specimens, hardener and HTPB were premixed and left at room temperature for 1 hr before epoxy addition. In order to observe the effects of short glass fiber reinforcement of epoxy matrix, silane treatment of fiber surfaces, and also rubber modification of epoxy on the mechanical behavior of specimens, tension and impact tests were performed. The fracture surfaces and thermal behavior of all specimens were examined by scanning electron microscope (SEM), and dynamic mechanical analysis (DMA), respectively. It can be concluded that increasing the short GF content increased the tensile and impact strengths of the specimens. Moreover, the surface treatment of GFs with SCA and HTPB modification of epoxy improved the mechanical properties because of the strong interaction between fibers, epoxy, and rubber. SEM studies showed that use of SCA improved interfacial bonding between the glass fibers and the epoxy matrix. Moreover, it was found that HTPB domains having relatively round shapes formed in the matrix. These rubber domains led to improved strength and toughness, due mainly to the “rubber toughening” effect in the brittle epoxy matrix.

A comparative fundamental study was performed regarding the notched impact toughening performance of various rubber modified semicrystalline polyethylene terephthalate (PET) systems. Various modifiers with and without functional groups were evaluated: ethylene- co -propylene rubber (EPR), maleic anhydride grafted EPR (EPR- g -MA), glycidyl methacrylate grafted EPR (EPR- g -GMA x ) and ethylene–glycidyl methacrylate copolymers (E–GMA x ). Both binary and ternary blends (consisting of a preblend of EPR and a functionalised modifier) were examined. The most effective toughening route for PET is provided by dispersing a preblend of EPR and a low amount of E–GMA x . A minimum dispersed phase concentration of 30 wt% is needed to obtain a pronounced improvement of the impact strength and to induce a brittle–ductile transition of the fracture mode. The impact behaviour of the rubber toughened PET is primarily controlled by the morphological characteristics, i.e. the interparticle distance. An equal critical interparticle distance (IDc) of 0.1 μm was established experimentally for the different GMA compatibilised systems. This IDc is found to be independent of the amount of GMA functionalities present, the way of incorporation in the chain (grafting or copolymerisation) and the nature of the compatibiliser. The ternary PET/(EPR/E–GMA8) blends provided the best ultimate mechanical properties, displaying highly (15-fold) increased impact strengths and reasonable elongations at break.

For a more complete understanding of the toughening mechanism of polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) blends, dynamic packing injection molding was used to control the phase morphology and rubber particle orientation in the matrix. The relative impact strength of the blends increased at low EPDM contents, and then a definite ductile-brittle (D-B) transition was observed when the EPDM content reached 25 wt %, at which point blends should fail in the ductile mode with conventional molding. Wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to investigate the shear-induced crystal structure, morphology, orientation, and phase separation of the blends. WAXD results showed that the observed D-B transition took place mainly for a constant crystal structure (α form). Also, no remarkable changes in the crystallinity and melting point of PP were observed by DSC. The highly oriented and elongated rubber particles were seen via SEM at high EPDM contents. Our results suggest that Wu's criterion is no longer valid when dispersed rubber particles are elongated and oriented. The possible fracture mechanism is discussed on the basis of the stress concentration in a filler-dispersed matrix. It can be concluded that not only the interparticle distance but also the stress fields around individual particles play an important role in polymer toughening.

Various experimental techniques and finite element modelling (FEM) were employed to assess mechanical and chemical properties of vinyl-ester (VE)/poly(acrylonitrile–butadiene–styrene) (ABS) blends with different ABS particle content. The blends were to be used as a toughening agent for interlayer toughened VE/glass composite material. Firstly, the materials' fracture toughness and tensile properties were examined, the results showing excellent toughening potential of the blends as well as a non-linear trend for fracture toughness as a function of ABS weight content. The tensile testing of the blends served to define the yield point of the materials and to obtain their stress–strain curves, which were then used as input into finite element analysis models. The mechanical testing results suggested that a chemical reaction may have occurred between the constituents of the blends. Based on the Raman spectroscopy results and mechanical testing data, 7% of ABS was believed to be the critical ABS content where significant changes in the materials' chemical composition and consequently in mechanical properties occurred. Finally, FEM was undertaken to further verify the existence of this sudden variation in material's properties.

In this study, a transparent acrylonitrile–butadiene–styrene polymer alloy was tested in a range of biaxial stress states and a yield locus was generated. The onset of microscopic damage was detected by in situ light transmission measurements. The macroscopic yield locus followed a linear behavior on an octahedral shear stress vs. mean stress plot and the onset of microscopic damage was dependent on both shear and mean stresses. Our findings indicate that macroscopic ductility arises from damage in the polymer at two distinct length scales. On the scale of the rubber particle (0.1–0.2 um), damage occurs via particle debonding from the matrix. At a length scale intermediate between the particle size and macro scale, damage occurs through the formation of micro crack arrays with a well-defined pattern.