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In this article, a rheological method that can predict the molecular weight distribution (MWD) of polymer was introduced. Using this method, the MWDs of four cellulose samples were compared from rheological data of the cellulose / N‐methyl morpholine N‐oxide (NMMO) / H2O solutions. The MWDs of cellulose also were determined by gel permeation chromatography (GPC) calibrated with narrow distribution polystyrene standards, using 0.5% lithium chloride (LiCl) in N,N‐dimethylacetamide (DMAc) as the eluent. Comparison of the results from rheology and GPC showed that the MW and MWD of cellulose could be roughly inferred from their rheological data. Although the differential MWD obtained from the rheological method was bell shaped and can not reflect the fine characteristics of cellulose as GPC, it may be feasible to compare the MWDs of cellulose by using the rheological method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 598–603, 2004 相似文献
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醋酸纤维素衍生物反渗透膜对低分子量有机物分离特性研究 总被引:2,自引:1,他引:2
黄继才 《纤维素科学与技术》1993,1(4):36-44
研究用醋酸纤维素衍生物氰乙基醋酸纤维素、羟丙基醋酸纤维素和醋酸纤维素反渗透膜对有机醇、有机酸及有机胺类水溶液的分离特性,考察操作压力对反渗透分离特性的影响,并应用不可逆热力学过程得出的Spiegler—Kedem膜输送方程解析实验数据,获得了反射系数σ、溶质渗透系数ω和溶剂水渗透系L_p等膜参数。 相似文献
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以单分散性聚苯乙烯为标样,建立了凝胶渗透色谱(GPC)测定芳氧基聚磷腈相对分子质量(Mr)及其分布的方法。通过实验研究,确定了实验条件,对不同批次的芳氧基聚磷腈样品进行了测试,并对实验重复性进行了考察。实验结果表明,该方法准确性高,重现性好,有助于芳氧基聚磷腈性能的研究,为聚合反应工艺条件的控制和调整提供了依据。 相似文献
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凝胶色谱实验条件对聚醚多元醇相对分子质量测定的影响 总被引:2,自引:0,他引:2
用凝胶渗透色谱(GPC)测定聚醚多元醇的相对分子质量及其分布。以四氢呋喃作为溶剂和流动相,探讨了样品浓度、色谱柱温度以及流动相流速等条件对实验结果的影响。结果表明,样品浓度控制在1.0-3.0 mg/mL,且保证待测样品浓度与标准样品浓度一致时,实验结果误差较小;实验温度在30-50℃范围内对结果影响不大;流速低于1 mL/min时结果出现较小偏差;重复性测定平均相对分子质量的相对标准偏差仅有1%。 相似文献
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凝胶渗透色谱法测定聚丙烯腈共聚物的平均分子量及分布的研究 总被引:2,自引:0,他引:2
通过一系列的条件试验,确定了最佳的凝胶渗透色谱(Gel Permeation Chromatography简称GPC)试验条件。采用宽分布的聚丙烯腈共聚物(Polyacrylonitrile简称PAN)标准样品,通过编制的计算机程序,模拟计算出PAN的GPC校正曲线方程,对宽分布的标准样品进行重复测定。重现性试验结果符合误差要求。本方法快速准确,可满足生产和科研的需要。 相似文献
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用凝胶渗透色谱 (GPC)测定PAN的平均相对分子质量及其分布。采用宽分布的PAN标准试样 ,在溶剂二甲基甲酰胺中加入 0 .0 4~ 0 .0 8mol/L的NaNO3替代LiBr ,提高了色谱柱的分离效果。用计算机模拟出PAN的GPC校正曲线方程 ,对宽分布的标准试样进行重复测定 ,结果相对标准偏差均小于 3 .5 %。 相似文献
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纤维素科学与技术研究进展 总被引:3,自引:0,他引:3
梁锋 《纤维素科学与技术》1993,1(3):1-14
本文综述纤维素科学与技术的研究进展。阐述了纤维素结构、纤维素的合成、纤维素液晶、功能纤维素、纤维素溶剂、纤维素裂解和纤维素的废物利用等的最新动态。 相似文献
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介绍了当前凝胶渗透色谱法测定树脂分子质量及其分布的情况,并将凝胶色谱柱与不同的检测器相连,如与黏度计、静态光散射、质谱技术、核磁共振等联用的方法,并且比较了它们用于测定树脂分子质量时各自的特点。 相似文献
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凝胶色谱法测定木素分子量及其分布 总被引:2,自引:0,他引:2
综述了凝胶色谱法测定本素分子量及其分布的方法和取得的进展。新型高效凝胶位的出现,使凝胶色谱法可以测定多种本素分子量。用凝胶色谱法测定木素的分子量,需要根据样品的性质选择色谱技、流动相和标样,并通过实验确定合适的色谱条件。本素样品可能需要经过适当的预处理以适应色谱柱和流动相的要求。 相似文献
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聚丙烯腈原丝相对分子质量及其分布的测试 总被引:1,自引:0,他引:1
采用凝胶渗透色谱仪(GPC)测定了聚丙烯腈(PAN)原丝的相对分子质量及其分布,对比了国产PAN原丝与进口原丝分子量及分布的差异,结果表明,相对于进口PAN原丝,国产PAN原丝相对分子质量分布较宽,并可能存在凝胶或微凝胶现象。最后分析了测试过程中的主要影响因素及其解决方法,提出严格控制实验和环境条件,注意仪器的保养和监控,是确保测试结果准确性的关键。 相似文献
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GPC法研究低顺式聚丁二烯相对分子质量分布 总被引:1,自引:0,他引:1
GPC法研究了低顺式聚丁二烯的相对分子质量分布,同时确定了日本Asaprene730A的LCBR为4支化星形聚合物。用偶联法合成了LCBR,并GPC分布曲线指导中试放大实验。 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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凝胶色谱测定聚合物相对分子质量及其分布 总被引:7,自引:0,他引:7
杨迪 《现代塑料加工应用》2005,17(6):36-39
凝胶色谱法是测定聚合物相对分子质量及其分布的最常用、快速和有效的一种分析方法。阐述了凝胶色谱法的分离机理,详细地介绍了凝胶色谱法中应用的不同标定方法。列举了近年来凝胶色谱法的部分应用实例,并介绍了多检测器连用技术在凝胶色谱表征聚合物结构和分子状态中的应用。 相似文献
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A semi-empirical model which employs polynomials based on general free radical polymerization kinetics, is developed to describe the molecular weight distribution data as well as to evaluate the average molecular weights of a variety of commercial thermoplastics including polystyrene, poly(methyl methacrylate) and low density polyethylene. These novel expressions are equally applicable to a natural rubber sample with a bimodal distribution. Least-squares methods for the classical Schulz and Flory distribution functions are introduced to handle the g.p.c. data of the above polymers. Comparison of the results collected from various analyses indicates clearly that the polynomial model is the most versatile one in the sense that it can be utilized to smooth out satisfactorily the molecular weight distribution data of many polymers. In general, the Wesslau distribution function is particularly good for the highly branched polyolefin and the Schulz model is fairly effective for the addition polymers of moderately sharp molecular weight distribution, presumably with . However, the Flory and Tung distributions are found to be rather inferior in the present studies. On the basis of the current findings, a new procedure is suggested to facilitate the computations of the true average molecular weights from g.p.c. data directly. 相似文献
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