The control of miscibility of PP/EPDM blends by adding lonomers and applying dynamic vulcanization

The control of miscibility for isotactic polypropylene (PP) and ethylene-propylene-diene terpolymer (EPDM) has been attempted by adding poly(ethylene-comethacrylic acid) (EMA) ionomers and by applying dynamic vulcanization. The rheological properties, crystallization behavior, and morphology of the dynamically vulcanized EPDM/PP/ionomer ternary blends were investigated with a Rheometrics dynamic spectrometer (RDS), a differential scanning calorimeter (DSC), and a scanning electron microscope (SEM). Two kinds of EMA ionomers neutralized with different metal ions (Na⁺ and ZN⁺⁺) were investigated. Blends were prepared on a laboratory internal mixer at 190°C. Blending and curing were performed simultaneously, i.e., EPDM was vulcanized with dicumyl peroxide (DCP) in the presence of PP/ionomer. The composition of PP and EPDM was fixed at 50/50 by wt% and the contents of EMA ionomer were vaired from 5 to 20 parts based on the total amount of PP and EPDM. It was found that the addition of ionomers and the application of the dynamic vulcanization were effective in enhancing the miscibility of PP and EPDM. The structure of the blends was controlled by the following three component phases, i.e., the phase of the dynamially valcanized EPDM, PP, and Zn-neutralized ionomer. The ternary blends showed more miscibility than the PP/EPDM binary blend. This is due to the thermoplastic interpenetrating polymer network (IPN) of the ternary blends. The structure and properties of the ternary blends differed, depending on the types and contents of ionomer, i.e., the ternary blend containing Na-neutralized ionomer did not show a thermoplastic IPN structure clearly, even though the blend was prepared by dynamic vulcanization. The ternary blend containing Zn-neutralized ionomer clearly showed the behavior of a thermoplastic IPN when the contents of ionomer and DCP were 15 parts and 1.0 part, respectively.     

Fracture mechanics investigation on the PP/EPDM/ionomer ternary blends using j-integral by locus method

The fracture mechanics investigation of the polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM)/ionomer ternary blends was performed in terms of the J-integral by measuring fracture energy via the locus method. Blends were prepared in a laboratory internal mixer. The composition of PP and EPDM was fixed at a 50/50 ratio by weight. Two kinds of Poly(ethylene-co-methacrylic acid) (EMA) ionomers were used. The J-integral value at crack initiation, Jc, of the PP/EPDM/EMA ionomer ternary blends were affected by the cation types (Na⁺ or Zn²⁺) and contents (5–20 wt %) of the added EMA ionomers. The ternary blend having 5 wt % of Na-neutralized ionomer showed a higher Jc value than that of any other ternary blends. The results were discussed with regard to the fracture topology by a scanning electron microscope (SEM). © 1994 John Wiley & Sons, Inc.     

Rheological properties and crystalline structure of the dynamically cured EPDM and PP/HDPE ternary blends

The rheological properties and crystalline structure of the polyolefin ternary blends of EPDM/polypropylene/high density polyethylene were studied. Blends were prepared in a laboratory internal mixer by two different methods. In blend–cure process, blending and curing were performed simultaneously and EPDM was cured by dicumyl peroxide (DCP) in the presence of PP/HDPE under shear. The cure–blend was to cure EPDM alone first under shear (dynamic curing) and then mix the cured EPDM with PP and HDPE. The effect of DCP concentration, intensity of the shear mixing, and the rubber/plastic composition were studied using capillary rheometer and X-ray diffractometer. The PP-rich ternary blends showed the effect of the mechanooxidative degradation of PP by shear and peroxide. The melt viscosity increased with increasing DCP concentration in blends of EPDM-rich compositions. X-ray diffraction studies revealed that the inclusion of 25 wt % of linear EPDM in the PP/HDPE mixture for the PP-rich ternary blends changed the crystal structure of polypropylene component in the ternary blends. However, the dynamic curing did not alter the crystal structure of PP or HDPE in the blends.     

Effect of SEPS as a novel compatibilizer on the properties and morphology of PP/PC/POE blends

A novel macromolecular compatibilizer, styrene-ethylene-propylene-styrene (SEPS) with high content of styrene, was investigated for the purpose of improving the compatibility of PP (polypropylene)/PC (polycarbonate)/POE (ethylene-octene copolymer) blends. SEPS shows a remarkable compatibilizing effect since it has a particular structure with the EP-compatible aliphatic segments, which is well miscible with the nonpolar PP and olefinic elastomer POE domains, and S-chain segments which exhibit strong affinity with PC because of the similar molecular structure. Its compatibilizing effect was examined in terms of the mechanical, morphological, and thermal properties. The compatibilized PP-based blends represent remarkable improvement in impact strength and balanced tensile strength. When 5 wt % SEPS was added to PP/PC/POE blends (20 wt % POE), the impact strength of the blends was enhanced from 24 to 43 kJ/m² without obvious drop in the tensile strength. Their morphologies show a decreasing and much more homogeneous size of dispersed PC and POE particles through addition of SEPS, and the fracture surface morphologies change from irregular mosaic to the mix of mosaic and striation, and finally the regularly distant striation. The special morphology structure that resulted from the effect of the compatibilizer could be a key for enhancement of toughness and balanced rigidity of the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comprehensively improved mechanical properties of silane crosslinked polypropylene/ethylene propylene diene monomer elastomer blends

The properties and structure of silane crosslinked polypropylene (PP)/ethylene propylene diene monomer (EPDM) elastomer blends had been carried out. Fourier transform infrared spectroscopy and gel content tests were employed to evaluate the crosslinking reaction of PP/EPDM blends. Crosslinking efficiency of PP/EPDM blends was investigated using thermogravimetric analysis, differential scanning calorimeter, dynamic mechanical analysis, dynamic rheology, and tensile testing. Tanδ curves of silane crosslinked PP/EPDM blends exhibited an obvious “gel point” originated from the formation of dynamic crosslinking network. The blend corresponding to the “gel point” presented comprehensively improved mechanical properties. These results demonstrated that characteristic rheological parameters showed close correlations with key mechanical properties of silane crosslinked PP/EPDM blends. Scanning electron microscopy images illustrated that crosslinking had remarkably changed the morphologies of PP/EPDM blends. The large deformation mechanism of these blends had been suggested.     

Effects of blend composition and dynamic vulcanization on the morphology and dynamic viscoelastic properties of PP/EPDM blends

The morphology and dynamic viscoelastic properties of isotactic polypropylene (PP) blended with oil-free/oil-extended ethylene–propylene–diene (EPDM) rubbers were studied. Unvulcanized and dynamically vulcanized blends with the compositions PP/EPDM = 50/50 and = 30/70 were investigated. The morphology was observed by phase contrasted atomic force microscopy. The dynamic viscoelastic properties were determined with a rheometer of plate–plate configuration. It was shown that the rheological behavior was strongly affected by both the composition and the morphology of the blends. Significant improvement in the flowability of the dynamically vulcanized blends was observed when oil-extended EPDM was used instead of the oil-free version. It was demonstrated that the rheological properties are mostly controlled by the elastomer phase at low frequencies, while in the high-frequency range the influence of PP becomes dominant. The peculiarities in the rheological behavior of the thermoplastic elastomers (uncured blends, TPE) and thermoplastic dynamic vulcanizates (TPV, dynamically cured blends) containing oil-extended EPDMs were traced to a limited compatibility between the PP and EPDM components in the melt. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Tensile properties and morphology of the dynamically cured EPDM and PP/HDPE ternary blends

The tensile properties and morphology of the polyolefin ternary blends of ethylenepropylene–diene terpolymer (EPDM), polypropylene and high density polyethylene were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured in the presence of PP and HDPE under shear with dicumyl peroxide (DCP). For comparison, blends were also prepared from EPDM which was dynamically cured alone and blended with PP and HDPE later (cure–blend). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastics composition was studied. The tensile strength and modulus increased with increasing DCP concentration in the blends of EPDM-rich compositions but decreased with increasing DCP concentration in blends of PP-rich compositions. In the morphological analysis by scanning electron microscopy (SEM), the small amount of EPDM acted as a compatibilizer to HDPE and PP. It was also revealed that the dynamic curing process could reduce the domain size of the crosslinked EPDM phase. When the EPDM forms the matrix, the phase separation effect becomes dominant between the EPDM matrix and PP or HDPE domain due to the crosslinking in the matrix.     

Use of a sodium ionomer as a compatibilizer in polypropylene/high‐barrier ethylene–vinyl alcohol copolymer blends: The processability of the blends and their physical properties

The effect of a sodium ionomer (ion.Na⁺) on the compatibility of polypropylene (PP)/high‐barrier ethylene–vinyl alcohol copolymer (EVOH) blends was studied in terms of the thermal, mechanical, and optical properties and morphology. The rheological behavior, tensile tests, and morphology of the binary blends showed that the miscibility of EVOH with PP was very poor. The miscibility of the polymers improved with the ionomer addition. In general, the ion.Na⁺ concentration did not alter the thermal behavior of the blends, but it did improve the ductility of the injection‐molded specimens. Scanning electron micrographs displayed better adhesion between the PP and EVOH phases in the samples with the ionomer. The mechanical improvement was better in the film samples than in the injection‐molded samples. A 90/10 (w/w) PP/EVOH film with 5% ion.Na⁺ and an 80/20 (w/w) PP/EVOH film with 10% ion.Na⁺ presented better global properties than the other blends studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1763–1770, 2004     

Study on morphology and viscoelastic properties of PP/PET/SEBS ternary blend and their fibers

The morphology development of polypropylene (PP)/polyethylene terephthalate (PET)/styrene‐ethylene‐butylene‐styrene (SEBS) ternary blends and their fibers were studied by means of scanning electron microscopy (SEM) in conjunction with the melt linear viscoelastic measurements. The morphology of the blends was also predicted by using Harkin's spreading coefficient approach. The samples varying in composition with PP as the major phase and PET and SEBS as the minor phases were considered. Although SEM of the binary blends showed matrix‐dispersed type morphology, the ternary blend samples exhibited a morphological feature in which the dispersed phase formed aggregates consisting of both PET and SEBS particles distributed in the PP matrix. The SEM of the blend samples containing 30 and 40 wt % of total dispersed phase showed an agglomerated structure formed between the aggregates. The SEM of the PP/PET binary fiber blends showed long well‐oriented microfibrils of PET whereas in the ternary blends, the microfibrils were found to have lower aspect ratio with a fraction of the SEBS stuck on the microfibril fracture surfaces. These results were attributed to a core‐shell type morphology in which the PET and SEBS formed the core‐shells distributed in the matrix. The melt viscoelastic behavior of the ternary blends containing less than 30 wt % of the total dispersed phase was found to be similar to the matrix and binary blend samples whereas the samples containing 30 and 40 wt % of dispersed phases exhibited a pronounced viscosity upturn and nonterminal storage modulus in low frequency range. These results were found to be in good agreement with the morphological results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rheological behavior of polyester blend and mechanical properties of the polypropylene–polyester blend fibers

The article deals with method of preparation, rheological properties, phase structure, and morphology of binary blend of poly(ethylene terephthalate) (PET)/poly(butylene terephthalate) (PBT) and ternary blends of polypropylene (PP)/(PET/PBT). The ternary blend of PET/PBT (PES) containing 30 wt % of PP is used as a final polymer additive (FPA) for blending with PP and subsequent spinning. In addition commercial montane (polyester) wax Licowax E (LiE) was used as a compatibilizer for spinning process enhancement. The PP/PES blend fibers containing 8 wt % of polyester as dispersed phase were prepared in a two‐step procedure: preparation of FPA using laboratory twin‐screw extruder and spinning of the PP/PES blend fibers after blending PP and FPA, using a laboratory spinning equipment. DSC analysis was used for investigation of the phase structure of the PES components and selected blends. Finally, the mechanical properties of the blend fibers were analyzed. It has been found that viscosity of the PET/PBT blends is strongly influenced by the presence of the major component. In addition, the major component suppresses crystallinity of the minor component phase up to a concentration of 30 wt %. PBT as major component in dispersed PES phase increases viscosity of the PET/PBT blend melts and increases the tensile strength of the PP/PES blend fibers. The impact of the compatibilizer on the uniformity of phase dispersion of PP/PES blend fibers was demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4222–4227, 2006     

EPDM/POE/PP热塑性硫化橡胶材料的制备及性能研究

以三元乙丙橡胶(EPDM)/乙烯-辛烯共聚物(POE)/聚丙烯(PP)为原料,在PP含量固定的情况下,将POE部分取代EPDM,采用动态硫化技术制备出EPDM/POE/PP三元热塑性橡胶材料(TPV),研究不同含量的POE对材料力学性能、流变性能和微观形貌的影响。结果显示,随着POE含量的增加,三元TPV材料的硬度和熔体质量流动速率不断增大;拉伸强度和断裂伸长率呈线性增大,当EPDM/POE/PP比例为45/40/15时,材料力学性能达到最大值。流变性能和微观形貌分析结果表明,EPDM/POE/PP三元TPV材料具有良好的综合性能。     

Modified ethylene-propylene-diene elastomer (EPDM)-contained silicone rubber/ethylene-propylene-diene elastomer (EPDM) blends: Effect of composition and electron beam crosslinking on mechanical,heat shrinkability,electrical, and morphological properties

In this investigation, a gamma radiation-induced methacrylic acid (MAA)-grafted ethylene-propylene-diene elastomer (EPDM) was used as a third component (g-EPDM) in silicone rubber (SiR)/ethylene-propylene-diene elastomer (EPDM) blends. These blends were electron beam (EB) crosslinked. The effect of blend composition, the presence of g-EPDM, and EB crosslinking on the mechanical, heat shrinkability, electrical, and morphological properties of SiR/EPDM blends have been studied. To investigate the effect of grafted EPDM (g-EPDM), 10 wt % of g-EPDM was added to immiscible SiR/EPDM blends. Both silicone and EPDM are blended in different proportions (70:30 and 30:70) with and without g-EPDM followed by compression molding. To improve the properties and investigate the crosslinkability of binary and ternary blends further, the SiR/EPDM blends were irradiated by electron beam at different doses (50, 100, and 150 kGy). The gel content was found to increase with EPDM content, the presence of g-EPDM, and radiation dose. The addition of g-EPDM led to improvement of tensile properties (tensile strength, Young's modulus, percentage elongation, and toughness), electrical properties, and shrinkability of blends. EB crosslinking further enhanced the above properties. Surface morphology (SEM) revealed that the presence of g-EPDM and the incorporation of EB crosslinking improved the above properties of blends. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47787.     

Effect of talc on the properties of polypropylene/ethylene/propylene/diene terpolymer blends

In the present study, the effect of talc content on the mechanical, thermal, and microstructural properties of the isotactic polypropylene (i‐PP) and elastomeric ethylene/propylene/diene terpolymer (EPDM) blends were investigated. In the experimental study, five different talc concentrations, 3, 6, 9, 12, and 15 wt %, were added to i‐PP/EPDM (88/12) blends to produce ternary composites. The mechanical properties such as yield and tensile strengths, elongation at break, elasticity modulus, izod impact strength for notch tip radius of 1 mm, and hardness with and without heat treatments and thermal properties, such as melt flow index (MFI), of the ternary composites have been investigated. The annealing heat treatment was carried out at 100°C for holding time of 75 h. From the tensile test results, an increased trend for the yield and tensile strengths and elasticity modulus was seen for lower talc contents, while elongation at break showed a sharp decrease with the addition of talc. In the case of MFI, talc addition decreased the MFI of i‐PP/EPDM blends. It was concluded that, taking into consideration, mechanical properties and annealing heat treatment, heat treatment has much more effect on higher yield and tensile strengths, elongation at break, elasticity modulus, impact strength, and hardness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3033–3039, 2006     

Influence of premade and in situ compatibilizers in polypropylene/ethylene–propylene–diene terpolymer thermoplastic elastomeric olefins and thermoplastic vulcanizates

During dynamic vulcanization of polypropylene (PP)/ethylene–propylene–diene terpolymer (EPDM) blends with dicumyl peroxide/triallyl cyanurate, there is a possibility of the generation of in situ graft links at the interface. Three potential compatibilizers (PP‐grafted EPDM, styrene–ethylenebutylene–styrene, and trans‐polyoctenamer) for PP/EPDM blends were first investigated as references to obtain a quantified insight into the effects to be expected from in situ graft links. Only the first compatibilizer showed some compatibilizing action in straight, unvulcanized blends, as evidenced by a slight increase in the tensile strength of the blend and a somewhat smaller EPDM particle size within the PP matrix. Also, dynamic mechanical testing, in particular, the glass‐transition temperatures of the PP and EPDM components, showed some signs of compatibilization. The PP‐grafted EPDM resembled most closely the structures of PP and EPDM. In the spectra obtained with high temperature, solid‐state NMR, there was an indication that PP–EPDM graft links were generated during the dynamic vulcanization process that still remained after the extraction of the free PP phase from the thermoplastic vulcanizate film. NMR relaxation experiments gave further evidence for the graft links formed in situ. In all cases, only qualitative indications could be achieved because of the extremely low number of graft links formed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3877–3888, 2006     

Morphology prediction and the effect of core‐shell structure on the rheological behavior of PP/EPDM/HDPE ternary blends

In this work, the morphologies of polypropylene (PP)/ethylene‐propylene‐diene (EPDM) rubber/high density polyethylene (HDPE) 70/20/10 blends were studied and compared with the predictions of the spreading coefficient and minimum free energy models. The interfacial tension of PP/HDPE, PP/EPDM, and HDPE/EPDM blends were obtained by fitting the experimental dynamic storage modulus data to Palierne's theory. The prediction results showed core‐shell morphology (core of HDPE and shell of EPDM) in PP matrix. The PP/EPDM/HDPE blends were respectively prepared by direct extrusion and lateral injection method. Core‐shell morphology (core of HDPE and shell of EPDM) could be obtained with direct extrusion corresponding to the predicted morphology. The morphology of PP/EPDM/HDPE blends could be effectively controlled by lateral injection method. For PP/EPDM/HDPE blend prepared by lateral injection method, HDPE and EPDM phase were dispersed independently in PP matrix. It was found that the different morphology of PP/EPDM/HDPE blends prepared by two methods showed different rheological behavior. When the core‐shell morphology (core of HDPE and shell of EPDM) appeared, the EPDM shell could confine the deformation of HDPE core significantly, so the interfacial energy contribution of dispersed phase on the storage modulus of blends would be weaken in the low frequency region. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Mechanical properties and morphological structures relationship of blends based on sulfated EPDM ionomer and polypropylene

The mechanical properties and morphological structures of blends based on Zn²⁺ neutralized low degree sulfated ethylene propylene diene monomer rubber (Zn–SEPDM) ionomer and polypropylene (PP) were studied. It was found that Zn²⁺ neutralized low degree sulfated EPDM ionomer and PP blends, which are new thermoplastic elastomeric materials, have better mechanical properties than those of PP/EPDM blend. Theoretical analysis of tensile data suggests that there is an increase of the extent of interaction between PP and EPDM in the presence of a low degree of Zn²⁺, which is also an indicator of better interfacial adhesion between PP and Zn–SEPDM than that between PP and EPDM. SEM results proved that the finer dispersed phase sizes and the shorter interparticle distances are the main reasons for the improved mechanical properties of the PP/EPDM blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1504–1510, 2004     

Relationship between interfacial tension and dispersed‐phase particle size in polymer blends. I. PP/EPDM

Simple blends with different viscosity ratios of the components as well as compatibilized blends varying both in type and content of compatibilizers were used to study the relation between interfacial tension and dispersed‐phase particle size for PP/EPDM (80/20 wt %) blends in this work. Four compatibilizing systems, poly(ethylene‐co‐methacrylic acid) ionomers (EMA–I), dicumyl peroxide (DCP), DCP combined with EMA–I, and DCP in combination with trimethylol propane triacrylate (TMPTMA), were used. For blends prepared in an internal mixer, a power law relation was found between capillary number and torque ratio of the blends' components. This relation was used to estimate the interfacial tension for the compatibilized blends. The relation between steady‐state torque of the blends as a measure of viscosity and the estimated values of interfacial tension were also investigated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3148–3159, 2002     

The Effect of Dynamic Vulcanization on the Properties of Polypropylene/Ethylene-Propylene Diene Terpolymer/Natural Rubber (PP/EPDM/NR) Ternary Blend

The effects of dynamic vulcanization on the process development and some properties, such as tensile properties, swelling index, gel content, crystallinity, and morphology, of the polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM)/natural rubber (NR) blends were investigated. Dynamically vulcanized blends show higher stabilization torque than unvulcanized blends. In terms of tensile properties, the tensile strength and tensile modulus (stress at 100% elongation, M₁₀₀) of the vulcanized blends have been found to increase as compared with the unvulcanized blends, whereas the elongation at break is higher in the blend with richer EPDM content. These results can be attributed to the formation of cross-linking in the rubber phase. The formation of cross-links in the rubber phase has also been proved by swelling index and gel content. The percentage of crystallinity of the blends is decreased by dynamic vulcanization. Scanning electron microscopy (SEM) micrographs from the surface extraction of the blends support that the cross-links occurred during dynamic vulcanization.     

PET/PC blends: Effect of chain extender and impact strength modifier on their structure and properties

Methylene diphenyl diisocyanate (MDI) affects the morphology, rheological, mechanical, and relaxation properties, as well as tendency to crystallize of PET in PET/PC/(PP/EPDM) ternary blends produced by the reactive extrusion. Irrespective of the blend phase structure, the introduction of MDI increases the melt viscosity (MFI dropped), resulting from an increase in the molecular weight of the polymer chains; the PET crystallinity was also reduced. MDI favors compatibility of PET with PC in PET/PC/(PP/EPDM) blends. This is explained by intensified interphase interactions on the level of segments of macromolecules as well as monomer units. The presence of MDI causes a substantial rise in the dynamic shear modulus within the high‐elastic region of PET (for temperature range between T_g,PET and that of PET cold crystallization); the processes of PET cold crystallization and melt crystallization become retarded; the glass‐transition temperatures for PET and PC become closer to each other. MDI affects insignificantly the blend morphology or the character of interactions between the disperse PP/EPDM blend and PET/PC as a matrix. PP/EPDM reduces the intensity of interphase interactions in a PET/PC/(PP/EPDM), but a rise in the degree of material heterogeneity. MDI does not change the mechanism of impact break‐down in the ternary blends mentioned above. Increased impact strength of MDI‐modified materials can be explained by higher cohesive strength and resistance to shear flow at impact loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011