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TiO_2/ZnO超细粉体共混改性PET的流变性能 总被引:1,自引:0,他引:1
将改性的二氧化钛/氧化锌(TiO2/ZnO)超细复合粉体应用于聚对苯二甲酸乙二醇酯(PET)的共混改性,研究了改性PET的流变性能及其纤维的力学性能。结果表明:改性PET共混物为非牛顿假塑性流体,其表观粘度随剪切速率的增大而减小;随着超细粉体含量增大,改性PET共混物非牛顿流动指数下降,熔体粘度对温度的敏感性增大,流变性能改善;当超细粉体质量分数为5%时,改性PET共混物粘流活化能可达81.5 kJ/mol;随着超细复合粉体添加量增大,改性PET纤维断裂强度下降。 相似文献
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文章以通用聚苯乙烯(GPPS)为粘结剂,采用毛细管流变仪研究了钕铁硼(NdFeB)与GPPS粘结磁体的流变行为。结果表明:NdFeB/GPPS体系为非牛顿型流动体系,遵从假塑性流体的流动规律;表观粘度随着剪切速率的增加而下降,随着磁粉含量的增加而上升;随着温度的升高,熔体的非牛顿指数呈增大的趋势,而随着磁粉含量的增加,熔体的非牛顿指数呈减小的趋势;粘流活化能随磁粉含量的增加而增大,随剪切应力的增加而降低,但变化均较小。 相似文献
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利用旋转流变仪和热失重分析仪对聚4-甲基-1-戊烯(PMP)的加工流变性和热稳定性进行了研究.结果表明:PMP的加工性能与均聚聚丙烯(PP)较为接近,但其熔点为236℃,其加工温度高于PP.PMP熔体为典型的假塑性流体,其非牛顿指数为0.2,对剪切速率敏感;同时PMP黏流活化能(83.00 kJ/mol)比PP的高,表... 相似文献
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采用CFT-500型毛细管流变仪,研究了不同预热时间下PET、PA66的流动曲线,非牛顿指数、熔体表观粘度及粘流活化能。结果表明:高聚物的流变性能与预热时间具有相关性,预热时间延长,熔体非牛顿指数下降,熔体表观粘度下降,粘流活化能增加。 相似文献
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The shear viscosity, extensional viscosity, and die swell of the PTT melt were investigated using a capillary rheometer. The results showed that the PTT melt was a typical pseudoplastic fluid exhibiting shear thinning and extensional thinning phenomena in capillary flow. There existed no melt fracture phenomenon in the PTT melt through a capillary die even though the shear rate was 20,000 s?1. Increasing the shear rate would decrease the flow activation energy and decline the sensitivity of the shear viscosity to the melt temperature. The molecular weight had a significant influence on the flow curve. The flow behavior of the PTT melt approached that of Newtonian fluid even though the weight‐molecular weight was below 43,000 s?1 at 260°C. The extensional viscosity decreased with the increase of the extensional stress, which became more obvious with increasing the molecular weight. The sensitiveness of the extensional viscosity to the melt temperature decreased promptly along with increasing the extensional strain rate. The die swell ratio and end effect would increase along with increasing the shear rate and with decreasing the temperature, which represented that the increase of the shear rate and the decrease of temperature would increase the extruding elasticity of the PTT melt in the capillary die. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 705–709, 2005 相似文献
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采用凝胶渗透色谱仪和核磁共振仪表征了一系列聚烯烃弹性体(POE)样品的结构,并用毛细管流变仪考察了其挤出稳定性、剪切依赖性和黏温依赖性,分析了熔体黏度与聚合物结构的关系。结果表明,随着剪切速率的提高,高相对分子质量的POE熔体易出现不稳定流动,挤出物表面发生畸变;相对分子质量越大、温度越低、共聚单体含越高,发生不稳定流动的临界剪切速率c越低;POE的剪切黏度很大程度上受相对分子质量的影响,与共聚单体的含量关系不大;不同相对分子质量及组成的POE熔体的黏流活化能相近,约为2.8×10^4 J/mol。基于Carreau、Cross和Arrhenius等方程,分别建立了关联熔体零切黏度与聚合物重均相对分子质量和温度关系的半经验式、关联熔体表观黏度与零切黏度和剪切速率关系的半经验式;两式可用于预测POE熔体的黏度,其适用范围为温度为130~190 ℃,剪切速率为10~2 000 s-1,重均相对分子质量(Mw)为4.2×10^4~1.24×10^5 g/mol。 相似文献
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通过熔融共混方法,采用环氧类扩链剂对聚乙醇酸(PGA)进行反应挤出改性,同时添加亚磷酸酯类抗氧剂来降低熔融加工过程中的热降解。研究了扩链剂与抗氧剂联用对PGA熔体质量流动速率、热稳定性、熔体流变性能以及抗水解性能的影响。结果表明,扩链剂与抗氧剂复配,PGA改性料的熔体质量流动速率由原料的44.2 g/10min下降至11.2 g/10min;起始分解温度T-5%(质量剩余95%的温度点)提高22.1℃;熔体黏度提高6倍以上;在提高了熔体强度的同时,改性料热稳定性明显改善,同时抗水解稳定性也有一定程度提高。 相似文献
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固相缩聚反应温度与时间对PET结晶的影响 总被引:1,自引:0,他引:1
研究了聚对苯二甲酸乙二醇酯(PET)切片在固相缩聚反应中特性粘数和结晶度随反应条件的变化及其热行为。结果表明:固相缩聚PET特性粘数随反应温度和反应时间不断增大,反应温度为215~ 225℃时较佳,随反应的进行新结晶产生,一定时间后结晶度增加缓慢并趋于平衡;DSC分析表明固相缩聚反应后的PET存在一个特征熔融峰(253℃左右)和固相缩聚峰,随着反应温度和反应时间的增加,固相缩聚峰不断向特征熔融峰靠拢,一定反应温度和反应时间后融合为单峰,之后低温峰跨过特征熔融峰向高温移动。 相似文献
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聚乙醇酸(PGA)通常可通过乙交酯开环聚合和乙醇酸熔融缩聚制得,但乙交酯开环聚合工艺复杂,导致PGA成本高。相较而言,乙醇酸熔融缩聚制备PGA工艺简单,成本较低,但难以获得中高分子量的PGA。因此,本文基于熔融/固相缩聚路线,系统研究了催化剂种类与含量、酯化温度、固相缩聚温度等聚合工艺条件对PGA外观形态、特性黏度和热稳定性的影响。发现三氟甲烷磺酸铋对乙醇酸熔融缩聚具有较好的催化效果,优化熔融/固相缩聚条件如下:催化剂含量为0.20%(质量),酯化温度为180℃,熔融缩聚和固相缩聚温度为210℃,固相缩聚时间为12 h。在该熔融缩聚条件下,PGA的最高特性黏度为0.36 dl/g,进一步固相缩聚处理可以将PGA的特性黏度提高到0.59 dl/g。 相似文献
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Pravin L. Shah 《Polymer Engineering and Science》1974,14(11):773-777
A rheological investigation of the saturated fatty acids as lubricants for PVC was made in a Sieglaff-McKelvey rheometer over a wide temperature range. Results reveal that with an increase in carbon chain, fatty acids became more effective in reducing the melt viscosity of PVC. It was also discovered that the maximum viscosity variation due to these materials was observed at 350°F. At test temperatures of 400°F and above, no major viscosity differences were observed. Furthermore, the changes in the melt viscosity were more pronounced at shear rates less than 200 sec?1. The usefulness of the measured viscosity variations at the critical test temperature of 350°F was shown by extrusion. An excellent correlation between the apparent melt viscosity and extrusion melt temperature was found. The criticalness of the test temperature in assessing the effect of lubricants on PVC flow is discussed. 相似文献
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The need for recycling of polymeric waste has been well recogmized as a result of the escalating prices of the petrochemical feedstocks and the growing awareness to curtail solid waste that causes environmental pollution. During processing, the molecular weight of the polymer is reduced due to thermal and shear degradation. Since the melt rheology of the processed material is sensitive to the changes in molecular structure, knowledge of the complete flow curve depicting the variation of melt viscosity with shear rate at processing temperatures is a useful tool for assessing the reprocessibility of waste material and for specifying the conditions of reprocessing. In the present paper, an effective method is proposed to generate the melt flow curves of polymer waste from knowledge of its melt flow index. The method makes use of a master curve that can be obtained by plotting the available viscosity data in terms of modified functions based on the melt flow index. The master curves characteristic of the particular generic resin type are presented for low-density polyethylene, polypropylene and polystyrene. 相似文献
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采用直接酯化熔融缩聚法合成了一系列不同含量的三羟甲基丙烷(TMP)改性共聚酯(BPET),并对其基本物性参数、结晶性能和流变行为进行了表征。结果表明,TMP加入量为1.536 %(摩尔百分含量,下同)时,BPET的特性黏度和相对分子质量明显提高;随TMP含量的增多,BPET的半结晶时间延长,熔融结晶峰温降低;随TMP含量的增大,BPET熔体的非牛顿指数变小,偏离牛顿流体的程度变大,表观黏度对切变速率的依赖性增强;在实验切变速率下,BPET的黏流活化能均低于均聚对苯二甲酸乙二醇酯(LPET)的黏流活化能,BPET不适合使用升高温度的方法来改善其流动加工性能。 相似文献