Effect of high density polyethylene addition and testing temperature on the mechanical and morphological properties of polypropylene/ethylene-propylene diene terpolymer binary blends

High density polyethylene (HDPE) was added to the polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM) binary blend, and the effect of testing temperatures on the modulus of elasticity, impact behavior and corresponding fracture morphology was analyzed. Modulus of elasticity generally decreased as the EPDM content increased regardless of the testing temperatures. However, it was found that the modulus of elasticity of PP/EPDM/HDPE ternary blend increased compared to PP/EPDM binary blend when tested at –30 and –60 °C. Notched Izod impact strength changed depending on the testing temperatures, however, there was not much difference between binary and ternary blends up to 20 wt% EPDM. However, at more than 30 wt% EPDM content, ternary blends showed higher impact strength compared to binary blends. Especially, at –30 °C, brittle-ductile transition was observed between 20 and 30 wt% EPDM. Subsurface morphology was also analyzed, and the relationship between the impact strength and the stress whitening zone was investigated. Scanning electron microscopy observation of impact fractured surfaces was conducted, and overall morphology was analyzed with respect to HDPE addition and testing temperature change.     

Preparation of composite dispersed phase morphologies in incompatible and compatible blends during melt processing

Most processing/morphology studies of multi-phase polymer blends have been concerned with controlling the size and shape of the dispersed phase. The dispersed phase is generally a pure homo- or copolymer (apart from low levels of interfacial modifier). This paper describes the preparation during melt processing of a complex polymer blend morphology known as a composite dispersed phase system. Microscopically this structure can be seen to be composed of three parts: two distinct phases with sub-inclusions within one of the phases. This system is a type of blend within a blend. Various microscopic techniques are used to show that a composite multi-phase morphology can be prepared in an incompatible polypropylene/ polycarbonate (PP/PC) blend as well as in a compatible polyethylene copolymer/polyamide blend. This structure has been generated at two compositions for polypropylene/ polycarbonate through melt blending. At 50% volume fraction (near the region of dual-phase continuity), simultaneous addition of components results in co-continuous polypropylene and polycarbonate phases with the latter containing small PP spherical sub-inclusions. At 25% PC (volume fraction) the generation of a composite dispersed phase in a polypropylene matrix is obtained by imposing phase inversion followed by controlling the mixing time. The morphology in this case consists of a polypropylene matrix, a polycarbonate dispersed phase and spherical polypropylene sub-inclusions within the dispersed polycarbonate. Partial stabilization of the composite morphology in incompatible blends with mixing time can be obtained through control of the viscosity of the dispersed phase. Polyethylene copolymer/polyamide blends have also been prepared by the phase inversion process and show that strong interfacial interactions between the polyamide sub-inclusions and polyethylene copolymer dispersed phase material results in complete stabilization of the composite dispersed phase morphology with very high retention of sub-inclusions persisting even after long mixing times.     

DCP用量对PP／EPDM共混物力学性能及形态的影响

过氧化二异丙苯（DCP）能有效降解PP;当DCP用量为2‰（质量分数）时,PP／EPDM共混物的冲击强度较高。共混物的相形态结构表明,EPDM橡胶粒子均匀地分散在基体中。     

Microstructural,thermal and rheological correlations to mechanical response of polyamide-6(glass filled)/polyetherimide blend: effect of ethylene-octene copolymer on toughening of blend

Melt mixed glass-filled polyamide 6(PA6)/polyetherimide (PEI) blends were prepared in a co-rotating twin screw extruder over the entire composition range of 0–100 wt% of polyamide 6. These blends were characterized by structural, rheological, mechanical and thermal properties. Crystallization behavior and phase morphology of the blends were also investigated. The blend with the composition PA6/PEI 75/25 showed overall improved mechanical properties along with low resultant viscosity which can be processed on standard equipment. Shear viscosity along with shear stress of the blends were analyzed using shear rheometer which concluded that the blends can be processed on standard equipment due to resultant low viscosity. Scanning electron microscope micrographs revealed that the morphology of the blends showed a two phase structure in which the minor phase was dispersed as domains in the continuous phase. Polyolefin elastomer (POE) as impact modifier was added to the above composition in the range of 0–15 phr to study its effect. The thermal characteristics of PA6, PEI, and PA6/PEI blends with and without POE were investigated using DSC and TGA which revealed that the melting temperature and crystallization temperature of the blend remained unchanged while XRD results showed percent crystallinity was increased slightly. Furthermore, it can be said that the blend with composition PA6/PEI 75/25 with 10 phr impact modifier loading was suitable for high end applications because it combines the high mechanical properties of glass-filled PA6 with inherent flame-retardant property of PEI while POE overcomes the physical weakness of moisture absorption.     

DCP用量对PP／EPDM共混物性能和形态的影响

用动态硫化法制备的PP／EPDM共混型热塑性弹性体的性能明显优于直接共混型PP／EPDM热塑性弹性体,这是由于模量低的EPDM柔性长链经化学交联后,强化对PP的增韧效果,而交联后又被扯断细化的EPDM的颗粒,改变了因EPDM相互缠结所导致的熔融粘度大,加工性能差的缺陷。制备PP／EPDM热塑性弹性体的关键是动态硫化,由于PP／EPDM共混物的动态硫化是一个融物理共混、化学引发交联和剪切细化分散为一体的复杂过程,材料的性能除决定于组成、组分性能和化学交联体系外,还强烈依赖于所采用的共混工艺方式及其条件。本章采用过氧化二异丙苯（DCP）作为硫化剂,研究了过氧化物用量对动态硫化PP（K8303）／EPDM共混物性能和形态的影响。     

尼龙6/聚苯乙烯共混物融合缝的形态及其对力学性能的影响

采用扫描电镜(SEM)、力学性能测定,研究了尼龙6／聚苯乙烯(PA-6／PS)共混体系融合缝的形态及力学性能．鲒果表明,分散相和连续相的粘度比对融合缝的形态有重要影响．当η分散相／η连续相＞1时,融合缝处分散相的形态不同于本体．融合缝处分散相沿融合缝取向;当η分散相／η连续相＜1时．融合缝处分散相的形态与本体形态相似．均以球形粒子分散于基体中。融合缝的存在使共混体系的力学性能有较大下降,主要由融合缝处分散相形态所致。     

Fracture toughness investigation of the dynamically vulcanized EPDM/PP/ionomer ternary blends using the J-integral via the locus method

The fracture mechanics investigation of the dynamically vulcanized EPDM and PP/ionomer ternary blends was performed in terms of the J-integral by measuring fracture energy via the locus method. The ternary blends consisting of EPDM, PP and ionomer were prepared in a laboratory internal mixer by blending and vulcanizing simultaneously. Vulcanization was performed with dicumyl peroxide (DCP) and the composition of EPDM and PP was fixed at 50/50 by weight. Two kinds of poly(ethylene-co-methacrylic acid) (EMA) ionomers were used. The J-integral values at crack initiation, J _c, of the dynamically vulcanized EPDM and PP/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 containing 20 wt% zinc-neutralized EMA ionomer and 1.0 p.h.r. DCP showed the highest J _c values of the blends. The results have been discussed with regard to the fracture topology observed by scanning electron microscopy (SEM).     

Highly toughened polypropylene/ethylene–propylene-diene monomer/zinc dimethacrylate ternary blends prepared via peroxide-induced dynamic vulcanization

Polypropylene (PP)/ethylene–propylene-diene monomer (EPDM)/zinc dimethacrylate (ZDMA) blends with remarkable toughness and extensibility were successfully prepared via peroxide dynamical vulcanization. A unique structure with the EPDM particles surrounded by a transition zone containing numerous polymerized ZDMA (PZDMA) nano-particles was observed for the first time by using transmission electron microscopy (TEM) examination, which contributed to the dramatically increase of Izod impact strength. Dynamic mechanical analysis (DMA) confirmed that the possible PZDMA graft products resulted from peroxide dynamical vulcanization improved the compatibility between EPDM and PP phases. The specific morphology of the PP/EPDM/ZDMA blends indicated that ZDMA can lead to size reduction and good distribution uniformity of the crosslinked rubber particles and the increase of adhesion between PP matrix and EPDM phases during deformation. The synergic effect of the increase in the effective volume of the EPDM phase, the improved compatibility and adhesion between EPDM and PP phases and the deformation of those fine rubber particles is believed to result in the remarkable high toughness and extensibility of the PP/EPDM/ZDMA blends. Particularly for the PP/EPDM ratio of 70/30, the PP/EPDM/ZDMA (70/30/9, w/w/w) ternary blends with the Izod impact strength nearly 2 times higher than PP/EPDM (70/30, w/w) binary blends and 15–20 times higher than PP are achieved; besides, the elongation at break of PP/EPDM/ZDMA ternary blends is 4–5 times higher than that of PP/EPDM binary blends.     

Morphological, rheological and mechanical characterization of polypropylene nanocomposite blends

In the present work, the effectiveness of styrene/ethylene-butylene/styrene rubbers grafted with maleic anhydride (MA) and a metallocene polyethylene (mPE) as toughening materials in binary and ternary blends with polypropylene and its nanocomposite as continuous phases was evaluated in terms of transmission electron microscopy (TEM), scanning electron microscopy (SEM), oscillatory shear flow and dynamic mechanical thermal analysis (DMA). The flexural modulus and heat distortion temperature values were determined as well. A metallocene polyethylene and a polyamide-6 were used as dispersed phases in these binary and ternary blends produced via melt blending in a corotating twin-screw extruder. Results showed that the compatibilized blends prepared without clay are tougher than those prepared with the nanocomposite of PP as the matrix phase and no significant changes in shear viscosity, melt elasticity, flexural or storage moduli and heat distortion temperature values were observed between them. However, the binary blend with a nanocomposite of PP as matrix and metallocene polyethylene phase exhibited better toughness, lower shear viscosity, flexural modulus, and heat distortion temperature values than that prepared with polyamide-6 as dispersed phase. These results are related to the degree of clay dispersion in the PP and to the type of morphology developed in the different blends.     

用SEM观察PE/PC共混物在拉伸和冲击作用前后的形态

介绍了典型的极不相容共混物（ＥＩＢ）聚乙烯／聚碳酸酯（ＰＥ／ＰＣ）体系的形态受组成的影响,以及共混物在受到拉伸前后,冲击前后的形态。通过扫描电子显微镜（ＳＥＭ）观察发现,组成不仅影响分散相粒子的大小,形状,还决定分散相与连续相的转变,共混物在受到拉应力（拉伸）和剪切应力（冲击）后,前者较多球状粒子变形成为有利于提高拉伸性能的纤维状,后者粒子和基体都发生了能提高抗冲击韧性的塑性变形。     

Effect of liquid additives on morphology and properties of thermoplastic elastomers prepared from phase-modified EPDM elastomer and isotactic polypropylene blends

Thermoplastic elastomers (TPEs) were prepared from ternary blends of ethylene propylene diene poly methylene rubber (EPDM), isotactic polypropylene (PP), and low loadings (5–10 phr) of different types of interfacial phase modifiers (like maleated EPDM, styrene-ethylene-co-butylene-styrene block copolymer, and maleated PP). These showed much improved physico-mechanical properties compared to the binary blend of EPDM-PP. The effects of non-polar paraffin oil and polar di-octyl phthalate liquid additives (5–20 phr) were investigated in these phase-modified ternary and binary EPDM-PP blends. Only 5 phr of liquid additives provided synergistic improvement in physical properties (maximum stress, modulus, and elongation at break) and generated improved finer morphology of the ternary blends as revealed from scanning electron and atomic force microscopy studies. Enhanced physical properties and dynamic mechanical properties of these blends were explained with the help of better phase morphology and enhanced crystallinity of the blends.     

The influence of interfacial interactions on the morphology and thermal properties of binary polymer blends

In order to understand the influence of interfacial modification in polyamide/ionomer/ polypropylene ternary blends, the binary blends were investigated. In this study two multiphase blends have been chosen, PP/ionomer and PA/ionomer, where the ionomer was a copolymer of polyethylene and of a mixture of methacrylic acid, zinc methacrylate and isobutylacrylate. The PP/ionomer blend is a classic example of an incompatible system which displays a high degree of interfacial voiding in SEM fracture surfaces, a strong negative deviation from additivity in the viscosity/composition relationship and an important coalescence effect on increasing dispersed phase concentration. This blend demonstrated increased nucleation and crystallization rate, compared to pure polypropylene. The second blend, PA/ionomer, demonstrates a very fine multiphase structure evident only after microtoming/etching of the sample, strong additive behaviour in the viscosity/composition curve. Formation of an amide bond was identified by Fourier transform-infrared spectroscopy. This evidence supports the conclusion that much stronger interactions exist between the ionomer and the polyamide than between the ionomer and the polypropylene.     

PP／EPDM共混物注射成型样条的断口形态和冲击性能

借助扫描电子显微镜观察了ＰＰ／ＥＰＤＭ共混物注射成型样条的冲击断口形态以及该共混物注射产条的芯－壳结构特征，研究了ＥＰＤＭ基体中的各向异性分布，不同冲击强度样品的断口形态以胶芯－壳结构和ＥＰＤＭ的各向异性分布对断口形态和冲击性能的影响。     

Compatibilized Polypropylene/Ethylene–Propylene–Diene-Monomer/Polyamide6 ternary blends: Effect of twin screw extruder processing parameters

Polypropylene (PP)/Polyamide6 (PA6)/Ethylene–Propylene–Diene-Monomer (EPDM) (70/15/15) ternary polymer blends compatibilized with Maleic-anhydride grafted EPDM (EPDM-g-MA) were prepared by melt blending using a twin screw extruder (TSE). Effect of TSE processing parameters including barrel temperature, screw speed and blending sequence on the mechanical properties of ternary polymer blends was investigated by application of Taguchi experimental design methodology. Three different levels of barrel temperature (220 °C, 230 °C, 240 °C), screw speed (90 rpm, 120 rpm, 150 rpm) and blending sequence (nominated as: S1, S2 and S3) were selected. The response variables were tensile properties and impact strength of the prepared samples which are directly affected by the blend microstructure. Investigation of the statistical–mathematical analysis results performed by the software depicted that the optimum processing conditions for the ternary blends investigated here, to achieve balanced tensile and impact properties, are 220 °C, 150 rpm and S2 blending sequence.     

Effect of montmorillonite on the morphologies and properties of monomer casting polyamide 6/polystyrene blends via successive in situ polymerization

Monomer casting polyamide 6 (MCPA6)/polystyrene (PS)/montmorillonite (MMT) ternary composites were prepared via successive in situ polymerization. The effects of Na⁺-MMT and OMMT on morphologies of MCPA6/PS blends have been studied by scanning electron microscopy (SEM) and transmission electronic microscopy (TEM). Incorporation of certain amount of Na⁺-MMT results in the diameter of PA6 dispersed microspheres in PS matrix increased significantly from several to dozens of micrometers. It was interesting to find that all Na⁺-MMT was dispersed only in the MCPA6 microspheres. However, a different morphology was observed in MCPA6/PS blend with incorporation of OMMT, especially when the content of OMMT ≥1 wt%. That is, the morphologies of the ternary blends change from dispersed PA6 microspheres/PS matrix to dispersed PA6 network with inclusion of local PA6 microspheres/PS matrix. It was surprising that OMMT dispersed in PA6 microspheres at low OMMT loading (i.e., 0.5 wt%), while OMMT was dispersed in PA6 network phase, not in PA6 microspheres phase at high OMMT loading (i.e., ≥1 wt%). The incorporation of a various amount of MMT affected the crystallization behavior of PA6 phase in the MCPA6/PS blends by the results of XRD and DSC. The MMT layers leaded to the co-existence of α-crystalline form and γ-crystalline form of PA6. Furthermore, the more the MMT contents, the stronger the intensity of the γ-peak. Another interesting phenomenon was that there was a remarkable difference in molecular weight of PA6 microspheres phase and PA6 network phase in MCPA6/PS/OMMT (2 wt%) ternary composites from GPC results.     

Sorption and diffusion of aromatic solvents through linear low density polyethylene–ethylene vinyl acetate blend membranes

An investigation has been made for understanding the transport behaviour of organic solvents through linear low-density polyethylene (LLDPE)/ethylene vinyl acetate (EVA) blend membranes with special reference to the effects of blend ratio, concentration of cross-linking agent, penetrant size and temperature. Attempts have been made to relate the transport parameter with the morphology of the blend. The various transport parameters such as diffusion coefficient (D), permeation coefficient (P) and sorption coefficients (S) were evaluated at different diffusion conditions. The results were compared with theoretical predictions and found that the diffusion process follows anomolous type behaviour. The blends show dispersed/matrix and co-continuous phase morphologies depending on the composition. Dynamic vulcanization leads to fine and uniform distribution of the dispersed domains with a stable morphology. Among the blends E₇₀ sample shows the maximum solvent uptake and E₃₀ the minimum. The solvent uptake of blend varies with concentration of cross-linking agent. Molecular size of the solvent is a decisive factor in the solvent uptake. The rate of sorption and maximum solvent uptake increase with increase of temperature. Irrespective of the solvents used, the maximum solvent uptake increases with increase of temperature. The observed sorptivity, diffusivity and permeability are associated with cross-link densities of different samples. The D, S and P values increase with increase of EVA content in the blend.     

振动共混对聚丙烯/聚碳酸酯流变性能的影响

在传统转矩流变仪上叠加机械振动制成了振动共混流变仪。实验证明，振动共混降低了70／30聚碳酸酯／聚丙烯共混物的粘度和储存模量，随着制备时的振动振幅和频率的提高，这种效果更加突出。但过大振幅振动中，低剪切与高剪切间的频繁更换，特别是明显的低剪切下相翻转转慢，导致形成了部分不稳定“双连续”相态，这时共混物粘度和模量反而比小振幅振动下制备的共混物的高。一个描述该体系表面张力／液滴半径之比与剪切速率关系的经验表达式较好地分析了流变参数与微观相形态之间的关系，说明了振动促使分散相粒子的破碎和两相的分散，确实影响共混物的相形态。振动共混对聚丙烯／聚碳酸酯流变性能的影响上海交通大学化学化工学院高分子材料研究所，上海　200240振动共混　聚丙烯　聚碳酸酯　流变性能　影响　转矩共混流变仪　相形态在传统转矩流变仪上叠加机械振动制成了振动共混流变仪。实验证明，振动共混降低了70／30聚碳酸酯／聚丙烯共混物的粘度和储存模量，随着制备时的振动振幅和频率的提高，这种效果更加突出。但过大振幅振动中，低剪切与高剪切间的频繁更换，特别是明显的低剪切下相翻转转慢，导致形成了部分不稳定“双连续”相态，这时共混物粘度和模量反而比小振幅振动下制备的共混物的高。一个描述该体系表面张力／液滴半径之比与剪切速率关系的经验表达式较好地分析了流变参数与微观相形态之间的关系，说明了振动促使分散相粒子的破碎和两相的分散，确实影响共混物的相形态。     

Morphology,interfacial and mechanical properties of polylactide/poly(ethylene terephthalate glycol) blends compatibilized by polylactide-g-maleic anhydride

Polylactide/poly(ethylene terephthalate glycol) (PLA/PETG 80/20 wt) blends compatibilized with polylactide-g-maleic anhydride (PLA-g-MAH) were prepared by melt blending and the rheological, morphological and mechanical properties of the blends were studied. PLA/PETG (80/20 wt) blend formed a typical sea-island morphology, while upon compatibilization, the size and size distribution of the dispersed phase decreased significantly and the 3 wt% PLA-g-MAH compatibilized blend exhibited the smallest phase size and the narrowest distribution of the dispersed particles. The interfacial tension between PLA and PETG was determined from the morphological characteristics and the viscoelastic response of PLA/PETG blends via using two emulsion models. A minimum for PLA/PETG blend containing 3 wt% PLA-g-MAH was observed from both Palierne model and G–M model. The elongation-at-break increased by ∼320%, from 6.9% for PLA to 28.7% for the blend containing 3 wt% PLA-g-MAH without significant loss in the tensile modulus and tensile strength.     

PP/EPDM/CaCO_3三元共混体系的脆韧转变研究

采用扫描电镜和材料力学性能试验方法研究了ＰＰ／ＥＰＤＭ／ＣａＣＯ３三元体系中ＣａＣＯ３的表面处理与其材料的缺口冲击韧性及产生脆韧转变现象之间的关系。实验结果及分析表明：体系中分散相颗粒周围向ＰＰ基体扩散、渗透或与之共结晶的ＥＰＤＭ部分是增韧ＰＰ的有效成分；较好的表面处理条件下，体系中加入较少量的ＥＰＤＭ即可使材料缺口冲击韧性和拉伸模量值同时达到较好水平。     

熔体的粘性和弹性对LDPE／PS共混物形态的影响

研究了粘性和弹性对低密度聚乙烯／聚苯乙烯共混物形态的影响。结果表明，不相容聚合物在均匀剪切流动中的分散程度以及分散相的形状与组分的粘度比、相对弹性和体积分数有关。当分散相的粘性和弹性较基相大得多时，随分散相的体积分数增加，球状的液滴形成葡萄串状。若两组分的粘性和弹性相当，在适中的混合比下，分散相产生高度变形。不管组分的粘反比和弹性比大小，若分散相的体积分数非常低，共混物的主要形态皆为分散相的球状液滴分散在基体中。