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介绍了氯化聚乙烯行业标准的发展,行业标准的效应,国内CPE产品的质量,CPE残余结晶度,溶乘值和熔融热焓的比较。 相似文献
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通过元素分析和DSC测定研究了CPE的含氯量对其玻璃化转变温度、内聚能密度和溶解度参数、以及CPE/磁粉复合材料性能的影响。结果表明,含氯量越高的CPE其玻璃化转变温度也越高;与分子链间作用力有关的内聚能密度和溶解度参数也越大;而CPE/磁粉复合材料的拉伸强度和伸长率则较低,硬度较高。 相似文献
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几种牌号的橡胶型氯化聚乙烯性能对比 总被引：1，自引：0，他引：1
对牌号为CM 3 5 2 ,CM 3 5L ,CM 3 5 2特制和CPE13 0B ,CPE13 5B ,CPE14 0B及CPE70 2P的橡胶型氯化聚乙烯生胶性能、未硫化胶性能、硫化胶物理性能和电气性能进行了对比。结果得出 ,CM 3 5 2L和CPE13 0B的门尼粘度较低 ,加工性能较好 ;CM 3 5 2L胶料的ML 最小 ,ts1 和t90 较长 ;CM 3 5 2特制和CPE14 0B硫化胶的拉伸强度最高 ;CPE70 2P和CM 3 5 2特制硫化胶电气性能较好。 相似文献
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The calculation of the molecular weight distribution (MWD) of a polymer from its rheological properties is an attractive method since rheological measurements are comparatively faster and cheaper than the classical gel permeation chromatography technique (GPC). The calculation, however, still has some drawbacks, such as the sensitivity of the mathematical solution involved (ill‐posed problem) and the limited frequency range covered by commercial rheometers, which can be especially critical for crystalline polymers, for which the time–temperature superposition is of limited worth. In this article, a new approach for evaluating the MWD from the storage modulus and the relaxation modulus curves is proposed. The method, based on the use of a neural network model, was employed to evaluate MWD from rheological data obtained with different isotactic polypropylene resins. The results show that this approach can be successfully used to compute MWD curves and should expand the range of application of the rheological technique. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1416–1423, 2000 相似文献
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Mastication can improve the plasticity and reduce the molar mass of natural rubber (NR). The end product properties greatly depend on the efficiency of mastication. For NR before and after mastication, the changes in molecular properties are mainly attributed to the effects of mechanical and thermo-oxidative degradation. We investigated the variations in molecular weight, molecular weight distribution, degree of branching, and thermal stability of NR after mastication at 35, 75, and 110 rpm for 20 min. The results show that NR has a smaller molecular weight, broader molecular weight distribution, and a lower degree of structural branching at higher rotor speeds. Additionally, the rheological measurements were compared with gel permeation chromatography results, and the comparative outcomes reflect a strong correlation between these data. Rheological analysis reveals considerable complex relationships, and this measurement is more efficient, simple, and convenient than the other technique. 相似文献
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用两段淤浆聚合工艺合成了具有宽峰或双峰相对分子质量分布的高密度聚乙烯（HDPE）／（乙烯／丁烯-1）共聚树脂的反应釜共混聚合物。随着丁烯-1用量的增加，共混物的密度、熔点、结晶度、拉伸屈服应力减小，而断裂伸长率增加。随着高相对分子质量共聚物的含量增加，熔点、密度、结晶度减小，相对分子质量分布的双峰特性也更明显。通过调整两段聚合物的熔体流动速率、两段聚合物之比来控制相对分子质量大小及其分布。控制第一段小分子数目，增加第二段相对分子质量或减小密度可获得最大耐环境应力开裂性能。 相似文献
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James J. Leahy Colin Birkinshaw 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(1):57-65
Peat bitumen obtained by solvent extraction of Irish high moor peat was subjected to chemical, structural and rheological characterisation. The bitumen was fractionated on the basis of solubility in n-heptane, toluene and ethyl acetate into wax, resin and asphaltene; each of these major constituent groups was further separated into sub-fractions by column chromatography using solvents of increasing polarity. All materials were chemically characterised by C, H, N and O content and infra-red spectroscopy. Molecular size distribution of the materials was determined by gel permeation chromatography and vapour pressure osmometry. Heats of fusion, measured using the differential scanning calorimeter, indicated that crystalline species were concentrated in the wax fraction. The rheological properties of the bitumen were investigated between 10 and 50°C, and the fractions were examined at 20°C. Following analysis as yield pseudoplastic fluids, flow behaviour was described in terms of yield stress, flow and consistency indices. The measured flow parameters were examined in the light of the structural implications of the calorimetry and the results of the chemical analysis. Carboxylic acids and esters which are found principally in the wax fraction are considered to be the dominating rheological influence in the bitumen, affecting physical behaviour through their ability to crystallise at low temperature and thus mechanically hinder flow, and through secondary bonding increasing viscosity in the liquid phase. 相似文献
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通过研究了以HDPE为基料生产高速通信电缆用绝缘料的分子量分布、流变性能和加工性能,在聚合时通过改变分子量调解剂量和工艺条件,改善其分子量分布使其具有双峰结构从而改善加工性能,结果表明:该产品具有优异的力学性能、介电性能、各项指标达到了邮电部YD/T760-1995标准;同时具有良好的加工性能,能够满足高速挤出的要求。 相似文献
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Fourier transform infrared spectroscopy ( FTIR) was used to determine characteristic absorption peaks of softwood kraft lignin and soda hardwood lignin. Remarkable spectral differences were noticed between the different lignins due to their various chemical structures. Proton nuclear magnetic resonance spectrometry (1H NMR) was employed to analyze the structure of lignin. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry ( MALDI‐TOF) provided important data regarding the molecular weight distribution of lignin. Thermal stability of softwood lignin was found to be remarkably higher than that of hardwood lignin. Softening temperature and glass transition temperature of lignin were measured by differential scanning calorimetry (DSC) which was useful in selecting an optimal temperature profile during extrusion process. Rheological studies provided valuable information about the viscosity of lignins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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