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分子量及其分布是聚酯的结构参数,影响聚酯的可纺性。通过控制PTA中PT酸含量,选择缩聚反应器类型,可以调整产品的分子量及其分布。 相似文献
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提出一种以分子量分布为目标的聚酯工业生产过程流程模拟方法,针对通用流程模拟软件Aspen Plus在逐步聚合(step-growth)反应机理下不能计算分子量分布指数和分子量分布曲线的不足,通过外置接口程序从后台运行的Aspen源文件(*.bkp/*.apw)中读取数据,实现分子量分布曲线的可视化和其他质量指标的计算。以聚对苯二甲酸丁二醇酯(PBT)工业生产中的预缩聚过程为建模实例,在Aspen Polymers Plus软件平台上建立基于严格过程机理的聚酯工业预缩过程框架模型。根据分子量及端羧基浓度随动力学参数变化的灵敏度,利用工业操作参数及分析数据整定动力学参数,进一步通过外置接口程序计算PBT的分子量分布,重均分子量、分子量分布指数误差分别为4.2%、5.6%,为聚酯生产过程的分子量分布可视化提供基础。 相似文献
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以PET预聚体为原料,在小型真空转鼓装置上用固相缩聚的方法合成了一系列的样品(另发表)。对这些样品进行测试的结果表明:固相缩聚合成的高分子量PET的分子量分布与熔融缩聚法合成的普通分子量PET的分子量分布相似,并无加宽现象,固相缩聚所得样品在DSC测试所得谱图上均有双熔融峰,且随着固相缩聚反应温度和时间的变化,双峰有规律地发生变化,对此我们用结构再组合理论进行了解释。对样品进行X射线衍射测试,结果表明:样品的结晶在反应的最初阶段便基本完成,结晶度与固相缩聚反应温度及时间基本无关。对样品进行动态力学性能测试,结果指出:经固相缩聚后,tanδ峰值显著下降,峰宽加大,峰位置向高温方向移动,这种变化也是在反应的最初阶段便完成,与固相缩聚反应的温度及时间无关。 相似文献
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本研究用刮膜蒸发器对制备中间相沥青的原料(软化点为60℃的石油沥青)进行了分离,并分别以未分离的沥青及分离出的重质沥青为原料在不同的条件下调制成中间相沥青。探讨了原料分子量分布及缩聚过程中温度、N2流量、缩聚时间对中间相沥青族组成分布、软化点和可纺性等性质的影响。 相似文献
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<正> 一 前言 我厂锦纶66连续缩聚工艺包括高压(表压18kg/cm~2)预缩聚和负压后缩聚两步,中间以一闪蒸器减压过渡。我们采用57%(重量)的66盐水溶液(同时加入一定量的分子量调节剂)进料,经高压预缩聚得到含水约7%(重量)、分子量约5000的预聚体,再经闪蒸、负压后缩聚进一步脱水、缩聚平衡得到分子量为14500左右的纤维级聚合体,然后直接纺丝。 相似文献
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《化纤文摘》1996,(3)
963065固相缩聚的长丝生产条件对其性能的影响Gutmann R.…;Chemiefasern/textilindustr豆e-1994,44,(4),E194一198(英)两神不同分子量的ngfon66样品在185一225℃进行固相缩聚,聚合体的粘度稳定增长。固定固相缩聚的温度,延长反应时间,粘度可达到最大值。与上述的粘度特性相对应,在相同的反应时间内,随反应温度和时间,聚合体的端狡基及端氨基分别降低,但此降低并不精确地反映在重均分子量的提高上,显然是随固相缩聚的进行,由于副反应导致上述端基的进一步降低,因而也就引起分子量分布即Mw/Mn的变化,即缩聚反应时间端基降低,按端基计算的… 相似文献
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《塑料》2017,(4)
聚碳酸酯(PC)作为增长速度最快的通用工程塑料,其阻燃性难以满足日益增长的应用需求。通过熔融聚合将磷元素引入PC聚合物链中难以得到较高分子量的含磷PC。因此采用固相缩聚法,以碳酸二苯酯(DPC)、双酚A(BPA)、3-(羟基甲基磷酰基)-2-甲基-丙酸为原料合成得到了含磷PC,分别通过NMR、GPC、DSC和TG对所得含磷聚碳酸酯的结构、分子量和分子量分布、玻璃化温度、热稳定性等进行了测试和表征。结果表明:通过固相缩聚可以明显提高含磷PC的分子量、玻璃化温度和初始分解温度;经固相缩聚后,含磷PC的数均分子量由2950 g/mol提高到10 900 g/mol;玻璃化转变温度由86℃提高到133℃;初始分解温度由238.8℃提高到361.3℃。 相似文献
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本文详细讨论了采用童展和函数法和董履和函数近似法对聚氯乙烯的分级数据的处理过程,获得了聚氯乙烯的Mn。Mw、和Mn及多分散指数,并作出了聚氯乙烯的重量微分分子量分布曲线图和重量积分分子量分布曲线图. 相似文献
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用凝胶渗透色谱法测试了超临界CO_2下合成的聚丙烯腈的相对分子质量及其分布,并详细研究了各种反应条件如:单体浓度、引发剂浓度、时间及CO_2压力对聚丙烯腈的相对分子质量、相对分子质量分布及转化率的影响。 相似文献
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聚天冬氨酸的合成及其粘均分子量对阻垢性能的影响 总被引:11,自引:0,他引:11
通过L-天冬氨酸热缩聚合成聚天冬氨酸(PASP)的一系列试验,研究了聚合反应温度和时闻对PASP产率和粘均分子量的影响,分析了PASP对CaCO3阻垢性能的变化规律。并用红外光谱和核磁共振技术(NMR)对聚合物结构进行了分析。结果表明,不同反应条件下PASP产品粘均分子量相差很大,PASP粘均分子量对其阻CaCO3垢效果有显著影响。通过控制反应温度和时间能够改善PASP的阻垢性能,结果是230℃时反应5h所得PASP阻垢效果最好,此时PASP粘均分子量约为10000。 相似文献
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A general logarithmic normal distribution is developed for simulating the molecular weight distribution of non-degradation polymers. Based on gel permeation chromatography data of number-average and weight-average molecular weights, a set of equations is derived to evaluate all averages of and all moments of polymer molecular weights. Results obtained from theoretical considerations demonstrate that the general logarithmic normal distribution is essentially independent of the distribution exponent, and as a consequence, Wesslau's and Koningsveld's distributions are identical in nature. Simulation experiments substantiate the above conclusion. 相似文献
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Tadaaki Miyano Takeshi Matsuura Srinivasa Sourirajan 《Chemical Engineering Communications》1990,95(1):11-26
The effect of the molecular weight of polyethersulfone (Victrex) polymers, the nature of the solvent and the polymer concentration on the effective hydrodynamic radius of polymer in the membrane casting solution was investigated. The membranes were prepared from the casting solutions studied above and ultrafiltration experiments were performed with polyethylene glycol solutes. The average pore sizes and the pore size distributions on the membrane surfaces were further calculated from the ultrafiltration performance data obtained above. Strong correlations were found between the effective hydrodynamic radius of the polymer in the casting solution and the average pore size on the membrane surface. The mechanism of the pore formation was proposed on the basis of the polymer size—pore size correlation. 相似文献
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Hybrid willow (Salix spp.) is a potential source of pulp as demonstrated by its fibre morphology, chemical composition and pulping kinetics. Fibre length and cell wall thickness measurements on one and two years old clones ranged from 0·49 mm to 0·70 mm and 2·5 μm to 3·6 μm respectively. Fibre length variation by annual growth layer varied from 0·5 mm in the first growth layer to about 1·1 mm in the last growth layer and the maximum growth rate occurred in the first two to three years for fourteen years old clones. The clones were producing more fibre fraction as indicated by volumetric composition. The UV absorptfvities of milled wood lignin was found in the range of 12·17 -14·31 Lg?1cm?1 at 278 nm and the presence of syringyl and guaiacyl lignin was observed. 13C-NMR results of acetylated milled wood lignin showed clonal structural variations during lignification process and the Klason lignin content of one and two years old clones ranged from 20·8% to 26·1%. Bulk kraft delignification of mature wood resulted in 5–6% higher yield than juvenile wood from the same clone and the pulping activation energy ranged from 98 kJ.mol?1 to 120 kJ.mor?1. 相似文献
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氯乙烯-二烯类单体悬浮共聚物凝胶点前的分子量模型 总被引:1,自引:0,他引:1
从氯乙烯(VC)两相聚合的特点出发,根据拟动力学常数法和分子量分布矩理论,建立了VC-微量二烯类单体悬浮共聚物凝胶点前的分子量模型,求得悬挂双键表现活性。结果表明:模型可很好地描述反应过程中分子量变化,悬挂双键表现活性下降一个数量级,物理效应对交联反应有较大的影响。 相似文献
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CURTIS H. WHITSON THOMAS F. ANDERSON INGOLF SØREIDE 《Chemical Engineering Communications》2013,200(1):259-278
This paper applies the gamma distribution model for describing both the molar and boiling point distributions of heptanes-plus (C7+) fractions. The three-parameter distribution model has been fit to TBP (true boiling point) data from forty-four samples of stabilized petroleum liquid (stock tank oil and condensate), obtained from separation of reservoir fluids. An excellent fit was achieved for both molar and boiling point distributions, though molar distribution seems to be more accurately described by the distribution model. Two of the parameters, α and η, were correlated and fit to empirical equations for both molar and boiling point distributions. Since the third parameter, β, is defined in terms of α,η, and either average molecular weight or boiling point, it appears that a generalized correlation for molar and boiling point distributions may exist. We have not developed such correlations in this work, but our results provide the necessary groundwork for further research. 相似文献