共查询到18条相似文献,搜索用时 140 毫秒
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本文采用毛细管流变仪对聚氯乙烯电缆料的加工流变性能进行了研究,分析并讨论了影响PVC流变性能的各种因素。结果表明:在试验温度下,增塑PVC的剪切应力均随剪切速率的增加而增大,但当剪切速率增加到一定程度后,剪切速率对剪切应力的影响变小;改性剂PM-1的加入可以大大降低在相同剪切速率下的剪切应力。改性剂PM-1使电缆料的剪切敏感性减小,牛顿性增强。虽然PM-1不能改变临界剪切应力值,但却使当临界剪切应力相应的熔体粘度减小,即临界剪切速率增大,这在实际生产过程中是十分有用的,即可以提高挤出速度而不致于产生熔体破裂。分子量减小,熔体表观粘度明显减小。熔体表观粘度随温度的升高而逐渐减小。 相似文献
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PA1010/MGEPR共混物的流变性能研究 总被引:2,自引:0,他引:2
以尼龙1010(PA1010)为基体,以马来酸酐接枝乙丙橡胶(MGEPR)为增韧剂,采用Brabender PLE331型塑化仪制备了PA1010/MGEPR共混增韧尼龙材料,测试了PA1010/MGEPR共混物的表观粘度、非牛顿指数和粘液活化能等流变能数,并重点讨论了其流变性能。实验结果表明:共混物的表观粘度随温度升高而降低;粘流活化能随剪切速率的增而而减小。共混物熔体的表观粘度随剪切速率和剪切应力的增大而降低,非牛顿指数n小于1,符合假塑性流体流动规律。 相似文献
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应用LVDV-Ⅲ+型可编程流变仪测定了微米级氧化铁悬浮液絮凝处理后的流变特性,考察因素包括悬浮液固相质量浓度、pH值、絮凝剂添加量、搅拌速度。结果表明,悬浮液浓度不同,其流变性能也表现出不同,在相同剪切速率下,高质量分数悬浮液的表观粘度和剪切应力都大于低质量分数悬浮液的表观粘度和剪切应力;pH对絮凝悬浮液流变性有重要的影响。絮凝悬浮液粘度随pH的增加先增大后减小,絮凝剂聚合氯化铝添加量为80 mg的条件下,pH=6.14时表观粘度最大;絮凝剂浓度的不同,对于悬浮液流变性能的影响也不同,在相同剪切速率下,添加高浓度絮凝剂悬浮液的表观粘度和剪切应力都大于添加低浓度絮凝剂悬浮液的表观粘度和剪切应力,增加絮凝剂浓度对提高悬浮液粘着性能具有积极意义;对悬浮液搅拌强度不同其流变性能也表现出不同,在相同剪切速率下,悬浮液的表观粘度和剪切应力随着测试前对它搅拌强度的增加表现出先增大后减小。 相似文献
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以40%高纤维含量的短切碳纤维增强尼龙(PA66/SCF(40%))复合材料为研究对象,采用高压毛细管流变仪对其挤出料粒进行稳态流变试验,并采用扫描电子显微镜(SEM)观察其注塑试样拉伸断面表观形貌,深入研究了高纤维含量下短切碳纤维增强尼龙的流变行为。结果表明,随着表观剪切速率增加,材料挤出过程中总压力降不断增加;随着温度增加,总压力降逐渐减小;PA66/SCF(40%)复合材料为假塑性流体,存在剪切变稀行为,在较高剪切速率下,纤维沿流动方向发生取向;材料挤出胀大比与弹性回复有关,挤出胀大比随剪切速率增加而增加,随温度增加而减小。 相似文献
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以自制双(4-羧苯基)苯基氧化膦(BCPPO)为共聚单体,通过原位共缩聚反应制得了BCPPO共聚酰胺66(FR-PA66)。应用毛细管流变仪测试了FR-PA66的流变特性。结果表明,FR-PA66的非牛顿指数为0.78~0.86,熔融时呈现剪切变稀行为,属假塑性流体。在固定剪切速率下,FR-PA66的剪切应力、表观粘度随BCPPO含量的增加呈现先增大后减小趋势,当BCPPO质量分数为3%时,FR-PA66的剪切应力、表观粘度达到最大。同时,FR-PA66的表观粘度对温度较为敏感,属温敏材料。 相似文献
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《工程塑料应用》2021,49(8)
以尼龙66为基体材料,添加碳纤维、增韧剂、流动改性剂等相关功能助剂,通过双螺杆挤出机制备了碳纤维增强尼龙66复合材料,采用注塑工艺制备了碳纤维增强尼龙66复合材料的标准试样,研究了碳纤维及流动改性剂含量对复合材料力学性能和熔体流动性能的影响。结果表明,提升碳纤维含量可以大幅度提高碳纤维增强尼龙66复合材料的力学性能,当碳纤维质量分数为35%时,复合材料的拉伸强度达到251 MPa,比纯尼龙66树脂提高了210%,弯曲强度由纯树脂的72 MPa提高到358 MPa,提高了397%,缺口冲击强度提高了178%,达到22 kJ/m~2。通过加入流动改性剂可以提高碳纤维增强尼龙66复合材料的熔体流动速率(MFR),并且不影响复合材料的力学性能,当流动改性剂的质量分数为1%时,碳纤维质量分数为25%的复合材料的MFR达到16.1 g/(10 min),比未添加流动改性剂时提高了193%,碳纤维质量分数为35%的复合材料的MFR为15.5 g/(10 min),比未添加流动改性剂时提高了319%。 相似文献
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应用LVDV-Ⅲ+型可编程流变仪测定了凝聚剂对氧化铁悬浮液的流变特性的影响。实验结果表明,高价凝聚剂对于悬浮液颗粒的凝聚能力要比低价凝聚剂更加明显;随着凝聚剂浓度的增加,悬浮液颗粒的凝聚程度也相应增加;凝聚剂种类的不同,对于悬浮液流变性能的影响也不同,高价凝聚剂对于悬浮液流变性能的影响比低价凝聚剂大。在相同剪切速率下,添加高价凝聚剂悬浮液的表观粘度和剪切应力都大于添加低价凝聚剂悬浮液的表观粘度和剪切应力;凝聚剂浓度的不同,对于悬浮液流变性能的影响也不同。在相同剪切速率下,添加高浓度凝聚剂悬浮液的表观粘度和剪切应力都大于添加低浓度凝聚剂悬浮液的表观粘度和剪切应力,增加凝聚剂浓度对提高悬浮液粘着性能具有积极意义。 相似文献
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M. E. Zeynali A. A. Yousefi I. Soltani 《Polymer-Plastics Technology and Engineering》2013,52(1):42-47
Reactive blends of ethylene propylene diene monomer (EPDM) and polyamide (PA) 66 were prepared in the single screw and twin screw extruder using maleic anhydride as coupling agent and dicumyl peroxide (DCP) as initiator. The optimum concentration of DCP for grafting maleic anhydride on EPDM was determined. The grafting efficiency was determined by Fourier transform infrared (FTIR) spectroscopy, and (DMTA) tests were conducted to determine the damping, loss, and storage modulus of PA 66 composites. A capillary rheometer and parallel plate rheometer were employed to characterize the rheological properties at high and low shear rates. It was seen that the glass fibers are not long and continuous, and they act as fillers, therefore reducing the damping in the composite. No significant change was observed in the glass transition temperature of the blend as compared with the individual components, especially PA 66. In malienated EPDM blends with increasing EPDM from 10 to 15%, the height of glass transition temperature peak increases. Capillary rheometer tests show that for all samples the apparent viscosity decreases with increasing shear rate, which is a characteristic of a non-Newtonian pseudo plastic fluid. The viscosity ration of malienated EPDM and PA 66 shows a considerable difference between them and only at higher shear rates do the viscosities get closer. 相似文献
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玻璃纤维增强HDPE熔体流变性能研究 总被引:1,自引:0,他引:1
采用毛细管式流变仪研究了不同温度条件下玻璃纤维(以下简称玻纤)增强HDPE复合材料熔体的流变性能,及其与材料界面粘结性、玻纤含量等的关系。实验结果表明:材料界面粘结强度越大,玻纤含量越高,熔体表观粘度对温度的敏感性减弱,对剪切速率的敏感性则增强。对该类材料的成型应选择稍高的加工温度及剪切速率较为适宜。 相似文献
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《塑料、橡胶和复合材料》2013,42(2):76-84
AbstractThe effect of electron beam (EB) radiation on carbon fibre reinforced (CF) thermoplastic (PBT, PPS, PA) composites was investigated. To clarify whether crosslinking could take place without or only with the presence of a crosslinking agent, special attention was paid to the incorporation of this agent into polymer sheets with a carbon fibre content of 50% by volume. The thermal and mechanical properties of the materials before and after exposure under different irradiation doses were evaluated. For materials based on PBT, PPS and PA46, no significant changes in properties after irradiation could be observed. However, CF/PA66 exhibited some changes in the presence of a crosslinking agent after irradiation, which could be related to an irradiation-induced crosslinking reaction. The effect of irradiation on the flexural properties was insignificant but an improvement in the creep behaviour was observed. Non-reinforced PA66 plates were also manufactured and a gel content measurement indicated that crosslinking was successfully induced. Additional studies allowed the changes in the polymer due to this crosslink to be quantified. 相似文献
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The dynamic elastic properties are important characteristics of composite materials. They control the vibrational behaviour of composite structures and are also an ideal tool for monitoring of the development of CFRCs’ mechanical properties during their processing (heat treatment, densification). The present studies have been performed to explore relations between the dynamic tensile and shear moduli and some structural features (viz., fibre fraction, fibre type, porosity, weave pattern of woven reinforcement) of various unidirectional or bi-directional fibre reinforced carbon/carbon composites, made out of PAN- or pitch-based fibres as reinforcements and phenolic resin or coal tar pitch as matrix precursors. The dynamic tensile and in-plane shear moduli were determined from resonant frequencies of a beam with free ends. The longitudinal dynamic Young’s modulus of unidirectional CFRC composites – besides its dependence on the original fibre modulus and fibre volume contents – also reflects changes induced in matrix and fibres by heat treatment. The in-plane shear modulus does not depend on the fibre type but there exists its distinct tendency to increase with increasing fibre fraction. For bi-directionally reinforced composites, the longitudinal tensile modulus is more sensitive to the fabric weave pattern than to the fibre type. Tensile modulus of diagonally cut specimens and in-plane shear modulus of longitudinally cut ones are mutually correlated and, therefore, simultaneously controlled by densification steps and graphitisation heat treatment. 相似文献