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1.
It has been shown in a previous paper in this series that important dilatation is produced by plastic deformation under tension of neat PP and PP/PA6/POE blends, for which the POE to PA6 concentration ratio equals 1/2. In this work, the detailed mechanisms of this volume change are investigated from electron micrographs (SEM and TEM) obtained in the deformed state. At low alloy content, it is thus observed that dilatation results from decohesion of the PA6 particles from the PP matrix. As the amount of PA6 and POE increases, voids are nucleated preferentially in the thicker POE interphase making a shell around the PA6 particles, and secondarily in isolated POE particles. Unexpectedly, it has been found that the overall volume dilatation decreases with total alloying content. This is interpreted by: (i) the increasing contribution of PA6 that intrinsically deforms with less cavitation than PP, (ii) the post-cavitation rubber-like stretching of POE particles and, (iii) the early formation of a percolating network of shear bands from the diffuse array of voids formed after the yield point. These mechanisms explain the gradual increase of the resistance to impact of the PP/PA6/POE as their alloying content is increased. 相似文献
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A series of polymer blends were designed and manufactured. They are composed of three phases: polypropylene (PP), polyamide-6 (PA6) and polyethylene-octene elastomer (POE) grafted with maleic anhydride. The weight fraction of PA6 was adjusted from 0 to 40% by increments of 10%, and the weight fraction of POE was systematically half that of PA6. The morphology, essentially made of PA6 particles dispersed in the PP matrix, was characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the extruded plates prepared with the blends, the shape of the dispersed PA6 particles showed an elongated ellipsoidal shape, whose aspect ratio increased somehow with alloying content. The POE modifier was observed both as a thin interlayer (less than 100 nm thickness) at the PP/PA6 interface, and as a few isolated particles. The elastic modulus and yield stress in tension are nearly constant for PP and blends. By contrast, the notched Izod impact strength increases very much with alloying content. This remarkable effect is interpreted in terms of POE interphase cavitation, enhanced plastic shear deformation and resistance of PA6 particles to crack propagation. 相似文献
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Brittle-ductile transition of PP/POE blends in both impact and high speed tensile tests 总被引:3,自引:0,他引:3
Polypropylene (PP)/octene-ethylene copolymer (POE) blends were studied in both impact and high speed tensile tests, in which the practical strain rate was 208/s. With the increase of the POE content, brittle-ductile transition (BDT) of PP/POE blends occurred in both the impact and high speed tensile tests. BDT also occurred with the decrease of the tensile speed when any of the PP/POE blends was drawn. The impact deformation of the notched impact samples was analyzed in details. Most of the strain loading of the notched impact samples is taken by the deformation of the narrow region near the notch tip in impact tests. The microunits of the deformation region deform in two methods: high speed tensile deformation and shear deformation because of the tensile speed gradients in the deformation region. At the beginning of impact tests, the strain rate at the notch tip reaches almost 6000/s. In rubber toughened plastics, the shear deformation decreases greatly because of the rubber particle cavitation. Thus, the impact deformation is really a high speed tensile deformation at the narrow region near notch tips. The BDTs in both impact and high speed tensile tests share the same mechanism. The notch sensitivity of plastics is essentially the tensile speed sensitivity of plastics. 相似文献
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New polymer blends of polypropylene random copolymer (PP‐R) and poly(ethylene‐octene) (POE) were prepared by melt‐blending process using a corotating twin‐screw extruder. The POE content was varied up to 35%. The toughening efficiency of POE for PP‐R was evaluated by the mechanical properties of the resulted PP‐R/POE blends. The crystallization behavior and morphology of the blends were also studied. Results show that POE acts as nucleation agent to induce the crystallization of PP‐R matrix at higher crystallization temperature. Super‐toughened PP‐R/POE blends (Izod impact strength more than 500 J/m) can be readily achieved with only 10 wt % of POE. The high toughness of PP‐R/POE is attributed to cavitation and shear yielding of matrix PP‐R, as revealed by the morphology studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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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 相似文献
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PA6/POE/EAA共混体系的相态与性能的研究 总被引:7,自引:0,他引:7
采用乙烯-1-辛烯共聚物弹性体(POE)为增韧剂、乙烯-甲基丙烯酸共聚物(EAA)作为增溶剂制备了以尼龙6(PA6)为基体的PA6/POE/EAA共混合金。详细研究了弹性体用量与共混体系的亚微观相态、力学性能和流变性能的关系。结果表明随着弹性体含量的增加,共混体系的分散相粒子尺寸大小没有明显变化,共混体系的冲击强度增加,拉伸强度和弯曲弹性模量降低。弹性体的增加使体系的熔体粘度降低,改善了体系的加工性能,但当POE增加到20%时,随着POE的增加,粘度不再下降。 相似文献
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通过改变共混物中乙烯辛烯共聚物(POE)与马来酸酐接枝POE(POE-g-MAH)的比例,研究了MAH含量对聚酰胺6(PA6)/POE/POE-g-MAH/纳米碳酸钙(nano-CaCO3)复合材料的微观结构和力学性能的影响。结果表明,MAH含量较高时,POE-g-MAH与PA6基体的相容性好,复合材料的冲击强度最高;制备工艺对复合材料的形态及力学性能有很大影响,采用两步法制备的复合材料中nano-CaCO3分散效果更好,其增容作用使弹性体分散相直径增大约100 nm,冲击强度较一步法提高21 %。 相似文献
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An ethylene‐octene copolymer (POE)/polypropylene (PP) thermoplastic elastomer was prepared through dynamically crosslinking by 2,5‐dimethyl‐2,5‐dilbuty (Peroxy) hexane (DHBP). The effects of DHBP concentration, POE/PP ratio, melt flow index (MFI) of PP, and mixer rotation on rheology and morphology of the thermoplastic elastomer were studied. The results showed that with increasing DHBP concentration or POE content, the size of crosslinked particles as well as the melt viscosity increased. Furthermore, agglomerates or a network structure formed as the size of crosslinked particles increased. The melt viscosity also increased as MFI of PP decreased, while the size of crosslinked particles decreased under the same condition. Research on the morphology of dynamically crosslinked POE/PP thermoplastic elastomer flowing through a capillary rheometer at different shear rates show that the reprocessing had little effect on the morphology of dynamically crosslinked elastomer. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers. 相似文献
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采用高级流变扩展系统(ARES)研究了聚丙烯(PP)/乙烯-辛烯共聚物共混体系的流变性能,探讨了乙烯-辛烯共聚物含量和 PP 种类对共混体系储能模量、剪切黏度和零切黏度的影响。实验结果显示,PP 结构和 POE 含量对 PP/POE 共混体系的剪切流变性能有显著影响,随着 POE 含量的增加,PP1/POE 共混体系的储能模量和剪切黏度增加的幅度明显小于 PP2/POE 共混体系,PP1/POE 共混体系和 PP2/POE 共混体系的储能模量和剪切黏度增加幅度较大分别发生在 POE 含量为20%~30%和10%~20%,即共混体系发生"脆—韧"转变阶段。PP/POE 共混体系中存在界面滑移现象,且 PP 和 POE 的界面相容性对界面滑移现象影响较大,其中 PP1/POE 的界面滑移比PP2/POE 的界面滑移更加明显。 相似文献
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A series of three-phase polymer blends, composed of polypropylene (PP) matrix, polyamide-6 (PA6) fillers and polyethylene-octene elastomer grafted with maleic anhydride (POE-g-MA) modifiers, were designed and manufactured. Their mechanical behavior under cyclic loading-unloading was studied by using a video-controlled testing system named as VideoTraction© system. It was found that with the increasing PA6 and POE content, the strain hardening became more and more prominent, the volume strain decreased, and the energy dissipated increased. A detailed examination of the cryo-fractured surfaces under SEM was undertaken. The microcavity nucleation, growth and coalescence were observed, and represent the main mechanisms of plastic deformation and damage. The high volume strain comes from the abundant formation of microvoids. On the contrary, the formation of microvoids resulted in relatively smaller quantity of energy dissipation. This result coincides well with the toughening mechanisms of polymer blends revealed by other peoples. 相似文献
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聚苯醚/PA6/弹性体多相共混物的形态结构和冲击性能研究 总被引:5,自引:0,他引:5
以SEBS,SEBS-g-MAH,POE-g-MAH作为增韧改性剂,单独或并用对聚苯醚(PPO)/PA6共混物进行增韧。TEM的结果显示,在所制备的多相体系中,SEBS大多被包容在PPO分散要中;而SEBS-g-MAH和POE-g-MAH均分散在PA6的基体中,形成了多种形态结构。冲击断面下方应力发白区的TEM照片上有大量的空穴,表明弹性体的空穴化是诱发剪切带,从而吸引能量的根源。 相似文献
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增容剂EAA对PA6/POE共混体系的相态及性能的影响 总被引:12,自引:2,他引:10
采用乙烯-丙烯酸共聚物(EAA)作为尼龙6/乙烯-1-辛烯共聚物弹性体(POE)共混体系的增容剂,详细研究了增容剂用量与共混体系的相态、力学性能和流变性能的关系。结果表明相容剂的加入使共混体系的分散性大大改善,分散相POE粒子明显细化,粒子较均匀地分散在PA6连续相中;相容剂的加入使体系韧性明显提高,拉伸强度和弯曲弹性模量下降,加工性能也得到改善,而且当每100份PA6/POE用量为85/15、EAA用量在4月份左右时,其增容作用达到饱和,综合性能达到最优。 相似文献
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PP/POE/纳米CaCO3复合材料流变性能的研究 总被引:2,自引:0,他引:2
研究了聚丙烯/聚烯烃热塑性弹性体/纳米CaCO3(PP/POE/纳米CaCO3)复合材料的流变性能,探讨了纳米CaCO3、POE添加量、剪切速率和温度对复合材料黏度的影响。实验数据显示,在较低剪切速率下,随纳米CaCO3添加量的增加,体系熔体黏度增加;在较高剪切速率下,随纳米CaCO3添加量的增加,体系黏度降低;增加POE添加量,复合体系的熔体黏度增大;纳米CaCO3的加入使复合体系的非牛顿指数减小,非牛顿性增强。PP/POE/纳米CaCO3(100/10/10质量份数,下同)体系具有高流动性,熔体流动速率达19.58g/10min。 相似文献
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共混工艺对PP/PA6/纳米SiO2复合材料力学性能的影响 总被引:1,自引:0,他引:1
以聚丙烯(PP)作为基体,经表面处理过的纳米二氧化硅(nano-SiO2)和刚性聚合物尼龙6(PA6)作为改性剂,添加5%的接枝POE作增容剂,采用不同的共混工艺制备PP/PA6/纳米SiO2复合材料。研究了熔融共混挤出次数和共混方法对PP/PA6/纳米SiO2复合材料力学性能的影响,借助扫描电子显微镜从断面形貌上分析了影响复合材料力学性能的因素。结果表明:采用二次挤出熔融共混比一次挤出熔融共混制得的复合材料力学性能要好;采用PP与纳米SiO2先熔融共混挤出制得粒料,再用PA6、接枝POE与粒料熔融共混挤出的共混方法制得的复合材料综合力学性能最优。 相似文献
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Dean Shi Fengdan Jiang Zhou Ke Jinghua Yin Robert Kwok‐Yiu Li 《Polymer International》2006,55(6):701-707
The melt rheological properties of binary uncompatibilized polypropylene–polyamide6 (PP–PA6) blends and ternary blends compatibilized with maleic anhydride‐grafted PP (PP–PP‐g‐MAH–PA6) were studied using a capillary rheometer. The experimental shear viscosities of blends were compared with those calculated from Utracki's relation. The deviation value δ between these two series of data was obtained. In binary PP–PA6 blends, when the compatibility between PP and PA6 was poor, the deformation recovery of dispersed PA6 particles played the dominant role during the capillary flow, the experimental values were smaller than those calculated, and δ was negative. The higher the dispersed phase content, the more deformed the droplets were and the lower the apparent shear viscosity. Also, the absolute value of δ increased with the dispersed phase composition. In ternary PP–PP‐g‐MAH–PA6 systems, when the compatibility between PP and PA6 was enhanced by PP‐g‐MAH, the elongation and break‐up of the dispersed particles played the dominant role, and the experimental values were higher than calculated. It was observed that the higher the dispersion of the PA6 phase, the higher the δ values of the ternary blends and the larger the positive deviation. Unlike uncompatibilized blends, under high shear stress with higher dispersed phase content, the PP‐g‐PA6 copolymer in compatibilized blends was pulled out from the interface and formed independent micelles in the matrix, which resulted in reduced total apparent shear viscosity. The δ value decreased with increasing shear stress. Copyright © 2006 Society of Chemical Industry 相似文献
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Continuous chaotic and shear mixing-induced morphology development of 60/40 w/w polypropylene/polyamide 6 (PP/PA6) blend and its nanocomposite with 5 wt% clay was investigated. PP and PP nanocomposite were mixed with PA6 in a single-screw extruder, respectively. Two screw geometries were used to induce chaotic and shear mixing, respectively. It was demonstrated that for PP/PA6 blend, the PA6 domains were transformed from large particles to short striations and to small droplets finally in shear mixing, whereas morphology of PA6 phase developed from lamellar layers to a partial continuous structure finally in chaotic mixing. For (PP/clay)/PA6 blend nanocomposite, the PA6 domains were deformed gradually from droplets to irregular fibrils in shear mixing and from short layers to thin fibrils in chaotic mixing. The PA6 fibrils formed finally in the latter were much thinner and uniform than those in the former. The dynamic storage moduli of samples prepared in both shear and chaotic mixing with these PA6 fibrils presented a solid-like response at lower frequencies. Moreover, the clay platelets dispersed initially in the PP phase migrated into PA6 phase finally in both shear and chaotic mixing and the exfoliation of clay platelets in PA6 phase was obviously improved in the latter. 相似文献