Mechanical properties and morphology of PA6/EVA blends

The mechanical properties of blends of polyamide6 (PA6) and ethylene vinyl acetate (EVA) at a blending composition of 0–50 wt % EVA were studied. The notched Izod impact strength of PA6 increased with the incorporation of EVA, the increase being more than 100% compared to PA6 at 10% EVA. The tensile strength and the tensile modulus of the blends decreased steadily as the weight percent of EVA increased. Analysis of the tensile data using predictive theories indicated the extent of the interaction of the dispersed phase and the matrix up to 20 wt % EVA. SEM studies of the cryogenically fractured surfaces indicated increase in the dispersed phase domain size with EVA concentrations. On the other hand, impact fractured surfaces of PA6/EVA blends indicated debonding of EVA particles, leaving hemispherical bumps, indicating inadequate interfacial adhesion between PA6 and EVA. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1593–1606, 2002     

Reactively compatibilised polyamide6/ethylene-co-vinyl acetate blends: mechanical properties and morphology

Mechanical properties and morphological studies of compatibilised blends of PA6/EVA-g-MA and PA6/EVA/EVA-g-MA were studied as functions of maleic anhydride content (MA) and dispersed phase (EVA-g-MA) concentrations, respectively at blending composition of 20 wt% dispersed phase (EVA-g-MA or combination of EVA and EVA-g-MA). The maleic anhydride (MA) was varied from 1 to 6 wt% in the PA6/EVA-g-MA blend, whereas MA concentration was fixed at 2 wt% in the ternary compositions with varying level of EVA-g-MA. ATR-IR spectroscopy revealed the formation of in situ copolymer during reactive compatibilisation of PA6 and EVA-g-MA. It was found that notched Izod impact strength of PA6/EVA-g-MA blends increased significantly with MA content in EVA-g-MA. The brittle to tough transition temperature of reactively compatibilised blends was found to be at 23 °C. The impact fractured surface topology reveals extensive deformation in presence of EVA-g-MA whereas; uncompatibilised PA6/EVA blend shows dislodging of EVA domains from the matrix. Tensile strength of the PA6/EVA-g-MA blends increased significantly as compared to PA6/EVA blends. Analysis of the tensile data using predictive theories showed an enhanced interaction of the dispersed phase and the matrix. It is observed from the phase morphological analysis that the average domain size of the PA6/EVA-g-MA blends is found to decrease gradually with increase in MA content of EVA-g-MA. A similar decrease is also found to observe in PA6/EVA/EVA-g-MA blends with increase in EVA-g-MA content, which suggest the coalescence process is slower in presence of EVA-g-MA. An attempt has been made to correlate between impact strength and morphological parameters with regard to the compatibilised system over the uncompatibilised system.     

Morphology and properties of PBT/nylon 6/EVA‐g‐MAH ternary blends prepared by reactive extrusion

Morphology and properties of poly(butylene terephthalate) (PBT)/nylon 6 (PA6)/EVA‐g‐MAH ternary blends were investigated. The blends were prepared in a corotating, intermeshing, twin‐screw extruder. The incorporation of maleic anhyride (MAH) grafted onto ethylene‐vinyl acetate copolymer (EVA) (EVA‐g‐MAH) in the PBT/PA6 binary blends decreased the tensile and flexural strength but increased the impact strength, while the mechanical properties of the PBT/PA6 blends were decreased with increasing PA6 content regardless of the presence or absence of the EVA‐g‐MAH. The morphology studies of the ternary blends showed gross phase separation. The rheological properties of the ternary blends suggested that excessively high reactivity between amine end groups of PA6 and MAH grafted onto EVA makes the compatibility between PBT and PA6 worse, although EVA‐g‐MAH was expected to work as a compatibilizer for PBT/PA6 blends. The degree of reactivity between functional groups in PBT, PA6, and EVA‐g‐MAH was also examined by investigating the effect of blending sequence on the properties of the ternary blends.     

Rheological and mechanical properties of compatibilized polystyrene/ethylene vinyl acetate blends

In this study, a blend of polystyrene (PS)/ethylene vinyl acetate (EVA) (PS/EVA, 90 : 10 wt %) was compatibilized with three different block copolymers, in which their end blocks were compatible with either styrene or EVA. The compatibilized blends with different compositions were prepared using a twin‐screw extruder and injection molded into the required test specimens. Mechanical properties of the blends, such as tensile properties and Charpy impact strength, morphology of tensile fractured surfaces, rheological properties, and thermal properties, were investigated. The results show that the interaction between the dispersed and continuous phase can be improved by the addition of a compatibilizer. Appreciable improvement in the impact strength of the blend with 15 wt % of compatibilizer C (polystyrene‐block‐polybutadiene) was observed. Its mechanical properties are comparable to those of the commercial high‐impact polystyrene, STYRON 470. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2071–2082, 2004     

热塑性淀粉增韧改性聚酰胺6的研究

将甘油增塑玉米淀粉制得的热塑性淀粉（TPS）与聚酰胺6（PA6）进行熔融共混,制备PA6/TPS共混物,研究不同含量的甘油和TPS对PA6/TPS共混物性能的影响,并探讨TPS增韧PA6的机理。采用万能试验机、溶体流动速率仪和扫描电子显微镜对改性PA6进行表征。结果表明,加入TPS后,共混物的冲击强度和拉伸模量有所提高,而拉伸强度和熔体流动速率略有下降,表明TPS对PA6起到了有机刚性粒子增韧的作用;TPS对PA6的增韧机理主要是界面脱黏、空化作用;甘油含量对TPS改性PA6的韧性影响显著,甘油含量为25 %的TPS添加量为25 %时,其增韧效果最好,冲击强度比PA6提高了63 %。     

PA6含量对PVC/PA6共混物形态结构与力学性能的影响

以EVA-g-MAH为相容剂,将PVC与自制的低熔点PA6共混制备了PVC/PA6共混物。通过扫描电子显微镜(SEM)和力学性能测试研究了PA6含量对PVC/PA6共混物形态结构及力学性能的影响。SEM分析结果显示:随着PA6含量的增加,PVC/PA6共混物的分散相尺寸逐渐增大,当PA6含量为10%时,共混物中分散相的分散尺寸最小为1μm;当PA6含量为50%时,共混物为两相共连续结构;当PA6含量为60%时,共混物中PA6为连续相,PVC为分散相。力学性能测试结果表明:当PA6含量为10%时,共混物的缺口冲击强度和拉伸强度都较PVC有明显提高,分别提高了约50%与30%,达到了6.29kJ/m2和60MPa。采用差示扫描量热仪(DSC)研究了PVC/PA6共混物的结晶温度,检测结果显示:PVC/PA6共混物呈现非晶结构。     

PA6／HDPE／EVA三元共混改性的研究

研究了PA6/HDPE、PA6/HDPE/EVA共混物的密度、热性能和力学性能。PA6/HDPE/EVA三元共混物的力学性能比PA6/HDPE二元共混物有明显提高。对于拉伸强度,EVA的最佳含量在2～4份。冲击强度随EVA含量的增加而提高,EVA的含量小于5份时,对共混物的硬度几乎没有影响。     

Mechanical properties of polystyrene/polyamide 6 blends compatibilized with the ionomer poly(styrene‐co‐sodium acrylate)

The compatibilizing effect of the ionomer, poly(styrene‐co‐sodium acrylate) (PSSAc), on immiscible blends of polystyrene (PS)/polyamide 6 (PA6) was studied by mechanical tests and scanning electron microscopy. The PSSAc acts as an effective compatibilizer because both the deformation at break (%) obtained by tensile stress–strain tests and the impact rupture energy are larger in blends containing small amounts of PSSAc. The morphologies of the fractured surfaces produced by tensile stress–strain tests of blends with or without the ionomer confirm that PSSAc increases the interfacial adhesion between PS and PA6 phases. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2545–2551, 2004     

PP/PA6共混比例对其水辅助注塑管件性能及微观形态的影响

以聚丙烯 (PP)为基材,聚酰胺6(PA6)为分散相,制备了4种共混比例的PP/PA6复合材料,考察了共混比例对其水辅助注射成型技术（WAIM）管件拉伸强度及微观形态的影响。结果表明,试样拉伸强度随PA6含量增加先减小后增大;近模壁层和近水层的PA6分散相为大长厚比的长条状或长片状,中间层分散相为椭球状,且随PA6含量增加各层分散相有聚集长大的趋势;管件近模壁层和近水层的晶粒小而密且沿流动方向排列,而中间层晶粒相对更粗大;PP只形成了一种晶型,PA6形成了2种晶型;近水层和近模壁层PP结晶度高于中间层;PA6随其含量增加其结晶度有增大的趋势,且近模壁层结晶度较高。     

Toughening and compatibilization of polypropylene/polyamide‐6 blends with a maleated–grafted ethylene‐co‐vinyl acetate

In this article, maleated–grafted ethylene‐co‐vinyl acetate (EVA‐g‐MA) was used as the interfacial modifier for polypropylene/polyamide‐6 (PP/PA6) blends, and effects of its concentration on the mechanical properties and the morphology of blends were investigated. It was found that the addition of EVA‐g‐MA improved the compatibility between PP and PA6 and resulted in a finer dispersion of dispersed PA6 phase. In comparison with uncompatibilized PP/PA6 blend, a significant reduction in the size of dispersed PA6 domain was observed. Toluene‐etched micrographs confirmed the formation of interfacial copolymers. Mechanical measurement revealed that the addition of EVA‐g‐MA markedly improved the impact toughness of PP/PA6 blend. Fractograph micrographs revealed that matrix shear yielding began to occur when EVA‐g‐MA concentration was increased upto 18 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3300–3307, 2006     

EVA对PP/EVA共混物力学性能的影响

将不同配比的聚丙烯(PP)和乙烯-乙酸乙烯共聚物(EVA)进行共混,测试了共混物的拉伸强度和冲击强度;用差示扫描量热法研究了共混物的结晶性能;用扫描电镜(SEM)二次电子成像系统分析了试样的断口形貌,研究了EVA含量对共混物力学性能的影响。结果表明:EVA的加入提高了EVA/PP共混体系的韧性,同时降低了PP的结晶度。     

Blends of nylon 6 with an ethylene-based multifunctional polymer. II. Property–morphology relationships

The tensile properties and impact strength were measured of the three blend systems, nylon 6/CXA 3101, nylon 6/Plexar 3, and nylon 6/EVA, which had been prepared using a twinscrew compounding machine. Scanning electron micrographs (SEM) of the fracture surfaces show that the domain size of the dispersed phase is much smaller in the nylon 6/CXA 3101 blends or nylon 6/Plexar 3 blends than in the nylon 6/EVA blends. This is attributed to the presence of a graft copolymer, formed by chemical reactions between carboxyl or anhydride groups present in the CXA 3101 (or Plexar 3) and the amino end groups of the nylon 6, at the boundaries of the dispersed and continuous phases. The SEM analysis of the fracture surfaces shows that no discrete particles are exposed on the fracture surface of either the nylon 6/CXA 3101 blends or nylon 6/Plexar 3 blends, supporting the theory that a graft copolymer, formed during melt blending, helped the discrete particles adhere to the continuous matrix.     

有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响

研究了有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响。结果表明,OMMT的添加可以提高体系的拉伸强度、弯曲强度和弯曲模量,但冲击强度会有某种程度的下降;OMMT主要分散在PA6连续相中,且当其添加量质量份数低于5%时,可以在PA6相中实现较充分的剥离;OMMT对PA6/PP合金体系有着显著的增容作用,这可能和片层对PP分散相凝聚时的阻隔,以及片层所起到的类似接枝物的增容作用有关;OMMT在PA6基体中被充分剥离后,将有利于使复合体系的拉伸强度、弯曲强度得到提高,但OMMT片层及和片层有关的类似接枝物的存在,将束缚并限制界面层附近PP相的屈服,而使材料冲击韧性下降。     

Comparison Properties of Natural Rubber (SMR L)/Ethylene Vinyl Acetate (EVA) Copolymer Blends and Epoxidized Natural Rubber (ENR-50)/Ethylene Vinyl Acetate (EVA) Copolymer Blends

Mixing torque, morphology, tensile properties and swelling studies of natural rubber/ethylene vinyl acetate copolymer blends were studied. Two series of unvulcanized blends, natural rubber/ethylene vinyl acetate (SMRL/EVA) copolymer blend and epoxidized natural rubber (50% epoxidation)/ethylene vinyl acetate (ENR-50/EVA) copolymer blend were prepared. Blends were prepared using a laboratory internal mixer, Haake Rheomix polydrive with rotor speed of 50 rpm at 120°C. Results indicated that mixing torque value and stabilization torque value in ENR-50 blends are lower than SMRL blends. The process efficiency of ENR-50/EVA blends is better due to less viscous nature of the blend compared to SMRL/EVA blends as indicated in stabilization torque graph. Tensile properties like tensile strength, M100 (modulus at 100% elongation) and E _b (elongation at break) increase with increasing EVA fraction in the blend. At the similar blend composition, ENR-50 blend shows better tensile properties than SMRL blends. In oil resistance test, swelling percentage increased with immersion time and rubber composition. At a similar immersion time, ENR-50 blends exhibit better oil resistance compared to SMRL blends. Scanning electron microscopy (SEM) of tensile fractured surface indicated that EVA/ENR-50 blends need higher energy to cause catastrophic failure compared to EVA/SMRL blends. In etched cryogenically fractured surface, size and distribution of holes due to extraction of rubber phase by methyl ethyl ketone (MEK) were studied and holes became bigger as rubber composition increased due to coalescence of rubber particle.     

Mechanical Properties and Morphology of Nitrile Rubber Toughened Polystyrene

Mechanical properties and morphology of blends of polystyrene and finely powdered (uncrosslinked and crosslinked) nitrile rubber were studied with special reference to the effect of blend ratio. Blends were prepared by melt mixing polystyrene and nitrile rubber in an internal mixer at 180°C in the composition range of 0–20 wt% nitrile rubber. The tensile stress/strain properties and impact strength of the polystyrene/nitrile rubber blends were determined using injection molded test specimens. In comparison to the blends with uncrosslinked nitrile rubber, blends with crosslinked nitrile rubber showed higher tensile strength, elongation at break, Young's modulus, impact strength, flexural strength, and flexural modulus. The enhanced adhesion between the dispersed nitrile rubber phase and the polystyrene matrix results in an increase in mechanical properties. Scanning electron micrographs of the fractured surfaces confirm the enhancement in mechanical properties.     

PP—g —HMA增容尼龙6／聚丙烯共混物结构与性能研究

采用固相力化学方法制备的聚丙烯接枝羟甲基丙烯酰胺作增容剂，制备了尼龙6／聚丙烯共混物，通过SEM、DSC、流变性能测试和力学性能测试研究了共混物的结构、流变性能和力学性能。 结果表明，当尼龙6体积分数为80％时，增容共混体系中冲击强度出现峰值，达到77J／m，分散相尺寸变小，增容共混体系熔融粘度增加。通过Molau实验和FT－IR分析对增容机理作了初步探讨。     

Nanocomposites formed from polypropylene/EVA blends

Rubber toughened polypropylene nanocomposites using two types of modified montmorillonite (organoclay) were explored with the objective of achieving an improved balance between stiffness and toughness. The effect of three blending sequences on microstructure and properties of the ternary nanocomposites was also investigated. A commercial grade of ethylene/vinyl acetate copolymer (EVA) containing 18 wt% of vinyl acetate was used as the impact modifier for polypropylene and an acrylic acid grafted polypropylene was used to compatibilize the systems studied. The toughened nanocomposites samples were prepared by melt compounding in a twin-screw extruder; the morphology and mechanical properties of the resulting materials were characterized by X-ray scattering, electron microscopy and tensile and impact testing. The results show that incorporation of EVA increases the toughness of the polypropylene but its stiffness decreased markedly due to the incorporation of the low modulus component. The addition of organoclay increased the modulus slightly for all the ternary nanocomposites with respect to the blend, but it remains lower than that of neat PP. Surprisingly, addition of organoclay to the blends promoted a drastic increase in the notched Izod impact strength and a considerable alteration of the shape of the dispersed EVA phase when the organoclay is located in this phase. Moreover, it was found that the blending sequence effects on the morphology and properties of the mixtures are dependent on the organoclay used.     

Improvement of polyamide/thermoplastic polyurethane blends with polyamide 6-polyurethane copolymer prepared via suspension polymerization as compatibilizer

The polyamide 6-polyurethane copolymer (PA6-b-PU-b-PA6) was synthesized through anionic suspension polymerization and then mixed with polyamide 6/thermoplastic polyurethane (PA6/TPU) and polyamide 6, 6/thermoplastic polyurethane (PA66/TPU) blends using as the compatibilizer. The results show that the PA6-b-PU-b-PA6 copolymers powders several can be obtained through suspension polymerization using dimethicone as disperse medium. The average diameter of PA6-b-PU-b-PA6 copolymer powders decreased with the increasing of PU content. With the addition of PA6-b-PU-b-PA6, the TPU phase dispersed more uniformly in PA6 or PA66 matrix, and the size of TPU dispersed phase decreased obviously. The PA6-b-PU-b-PA6 copolymer with higher PU content shows better compatibilizing effect. Addition of PA6-b-PU-b-PA6 can improve both strength and toughness of the PA/TPU blends. When the amount of PA6-PU25% copolymer was 5 phr, the tensile strength and notched impact strength of PA6/TPU/PA6-PU25% blends increased 29 and 159.4%, respectively, compared to the PA6/TPU blend without compatibilizer.     

Study on the microstructures and mechanical behaviour of compatibilized polypropylene/polyamide‐6 blends

A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐g‐MA) or with maleated PP (PP‐g‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by means of tensile and impact testing and by scanning electron microscopy and transmission electron microscopy. The results indicated that the miscibility of PP–PA6 blends was improved with the addition of POE‐g‐MA and PP‐g‐MA. For the PP/PA6/POE‐g‐MA system, an elastic interfacial POE layer was formed around PA6 particles and the dispersed POE phases were also observed in the PP matrix. Its Izod impact strength was four times that of pure PP matrix, whilst the tensile strength and Young's modulus were almost unchanged. The greatest tensile strength was obtained for PP/PA6/PP‐g‐MA blend, but its Izod impact strength was reduced in comparison with the pure PP matrix. © 2002 Society of Chemical Industry     

Compatibilization of polypropylene/nylon 6 blends with a polypropylene solid‐phase graft

The compatibilization of polypropylene (PP)/nylon 6 (PA6) blends with a new PP solid‐phase graft copolymer (gPP) was systematically studied. gPP improved the compatibility of PP/PA6 blends efficiently. Because of the reaction between the reactive groups of gPP and the NH₂ end groups of PA6, a PP‐g‐PA6 copolymer was formed as a compatibilizer in the vicinity of the interfaces during the melting extrusion of gPP and PA6. The tensile strength and impact strength of the compatibilized PP/PA6 blends obviously increased in comparison with those of the PP/PA6 mechanical blends, and the amount of gPP and the content of the third monomer during the preparation of gPP affected the mechanical properties of the compatibilized blends. Scanning electron microscopy and transmission electron microscopy indicated that the particle sizes of the dispersed phases of the compatibilized PP/PA6 blends became smaller and that the interfaces became more indistinct in comparison with the mechanical blends. The microcrystal size of PA6 and the crystallinity of the two components of the PP/PA6 blends decreased after compatibilization with gPP. The compatibilized PP/PA6 blends possessed higher pseudoplasticity, melt viscosity, and flow activation energy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 420–427, 2004