含内环化的A_a-B_b型缩聚反应

本文应用唐敖庆等曾建议的含内环化A_a-B_b型缩聚反应理论,分析了已二酸-三羟甲基丙烷缩聚反应.总结了溶胶分数、环化反应程度等的变化规律,讨论了内环化对凝胶点的影响,并进一步计算了凝胶点后的数均、重均和Z-均分子量.通过对实验数据的分析,验证了唐敖庆等建议的含内环化固化理论是合理的.     

高效凝胶渗透色谱法在若干重质化工产物分析中的应用

为配合酚醛树酯、十八烷基苯乙烯基醚聚合物新材料的生产、催化条件下煤直接液化的研究，建立了各试样分子量表征的高效凝胶渗透色谱法（ＨＰＧＰＣ），高分辨地测定了分子量分布、重均分子量Ｍｗ、数均分子量Ｍｎ。表征了不同产品的组成特性，有效地指导了工艺生产和基础研究。     

从GPC谱图和[η]获得Mw的误差分析——正态分布型模型GPC谱图

 本文利用正态分布型模型GPC谱图从理论上分析了利用GPC谱图和特性粘数来求样品重均分子量可能引入的误差问题。理论和实验表明,当样品的α在0.6—0.8之间,分子量分散指数M_w/M_n<10时,利用文献[3]提出的方法计算近正态分布的试样的重均分子量的误差不会大于10％。而且分子量分布越窄,α值越接近0.6185,所得的结果越准确。     

气相渗透法测定数均分子量的仪器常数问题研究

讨论了蒸气压渗透计仪器常数的分子量依赖性问题．通过对某些已知分子量化合物的温差信号随时间变化的研究，提出了测量四个低分子一种改进的ＶＰＯ信号的测量手续和数据处理方式，可以得到更为准确的数均分子量．     

从特性粘数和GPC图谱获得重均分子量的新方法

本文提出了从未知样品的特性粘数和GPC图谱计算重均分子量的新方法,该方法可用于计算窄分布和宽分布的未知Mark-Houwink 常数的样品的重均分子量。用七个不同分子量和不同分布的实例验证了所提出的方法。结果与已知Mark-Houwink常数用普适校准法得到的结果一致。     

松香改性特辛基酚醛树脂分子量GPC表征

本文利用凝胶渗透色谱法（GPC），建立了最佳测试条件，测试了松香改性特辛基酚醛树脂的分子量（重均、数均、分布指数），相对误差为2．46％、标准偏差为1．49、变异系数为4．94％，数据重视性较好。本方法操作简单，准确度、精密度均达到罗高要求。为这一类型高聚物的分子量测定提供了科学依据．     

凝胶色谱和1,2聚丁二烯的溶液性质

本工作根据凝胶色谱柱的单分散校准关系和试样的实效关系间的理论联系,建议了一个从一组重均和数均分子量确知的多分散试样的实验谱图,同时订定凝胶色谱柱的分子量校准关系和扩展因子的计算觅数方法。     

常温凝胶渗透色谱法分析C5加氢石油树脂的相对分子量及分布

通过凝胶渗透色谱（GPC）,采用普适校准法对C5加氢石油树脂的相对分子质量及分布进行测定.方法选取适合有效的小分子物质作为标准物质,测得样品的数均分子量约Mn=500,重均分子量约Mw=900。结果表明,方法不仅数据准确、可靠、重现性好,而且精密度高,绘出的图谱具有直观性,这对研究石油树脂的机械性能、流动性和成型加工性等有着极其重要的意义,为C5加氢石油树脂生产工艺提供了行之有效的分析方法。     

从特性粘数和GPC谱图获得数均分子量方法的误差分析

凝胶渗透色谱法(GPC)广泛用于测量高聚物的分子量及其分布,但即使是根据普适校准原理也需知道溶液体系的K、α值。已经提出了几种改进方法来估算分子量,其中文献[2]提出利用特性粘数和GPC谱图来估算平均分子量。后来有些学者从实验角度对此方法     

二氧化碳共聚物的分子量表征(GPC和特性粘数法)

脂肪族聚碳酸酯的分子量表征问题可以从GPC数据阳特性粘数较迅速可靠地解决,同时求出其数均,粘均,重均,动力学平均分子量,及其分子量—特性粘数关联参数。为此须对以往方法作较大的改进,其关键是用迭代法进行特性粘数(dL/g)与分子量的关联。如此对聚碳酸亚丙酯和碳酸亚乙酯分别得到以下关系: ln(η)=-6.671+0.328ln(?)v+0.0186(ln(?)v)~2 (25℃,THF) (η)=6.64×10~(-5)(?)v~(0.76) (25℃, CHCl_3)     

高分子无扰尺寸的测定

本文用GPC-[η]联用仪测定高聚物分子的无扰尺寸,GPC将高聚物分成不同的级分,连用自动粘度计测其相应级分的粘度,并由GPC的标定线或普适标定线,得到各级分的分子量,再用使Mark-Houwink公式线性化的理论方程,图解外推到无扰状态,获得高聚物分子的无扰尺寸,对于聚苯乙烯和聚甲基丙烯酸甲酯,所得结果与直接法、习惯法一致。     

Gel-permeation chromatography. IX. Instrumental design and computer interfacing of a GPC molecular weight detector system

The detailed design and computer interfacing of a GPC molecular weight detector based on a real time viscometer are described. The working drawings presented will permit one to fabricate and duplicate the viscometer and the complete GPC molecular weight detector system. The uses and advantages of a laboratory automation system in analyzing GPC results are also described.     

Low-density polyethylene: Variation of branching frequency with molecular weight and its influence on molecular weight as determined by gel-permeation chromatography

A method for determining long-chain branching frequency and molecular weight averages for unfractionated low-density polyethylene (LDPE) by the combined use of gel-permeation chromatography (GPC) and intrinsic viscosity data has been reported (GPC–IV method). The method assumes that the number of long branches λ per unit molecular weight is a constant independent of molecular weight. Recent data reported on λ as a function of molecular weight M in commercial LDPE indicate that this assumption is not generally valid, and concern has been expressed as to the size of the errors in molecular weights calculated using this assumption. The errors associated with assuming that λ is constant were evaluated in this study by first determining the way in which λ varies with M for two typical commerical LDPE resins by fractionation and application of the GPC–IV method to representative fractions. The experimentally determined relations between λ and M were then employed in the calculation of molecular weight and molecular size averages from GPC–IV data on the original unfractonated samples. Although it was found that λ increases with molecular weight for both samples, the results indicate that the error involved in assuming that λ is a constant is no greater than the precision with which molecular weight averages can be evaluated by GPC.     

Polymer characterization by coupling gel-permeation chromatography and automatic viscometry

A method is proposed for use of the universal calibration curve, i.e., the product of molecular weight and intrinsic viscosity versus retention volume, in calculating the molecular weight distribution of a polymer from gel-permeation chromatography (GPC) when the Mark-Houwink relation of the polymer in the solvent used for the GPC is unknown. This is achieved by measuring the viscosity of each fraction with an automatic capillary tube viscometer. Application of this technique to poly(vinyl chloride) and poly(vinyl acetate) proved to be successful.     

Characterization of Polyethylene in Dibutoxymethane by High-Temperature Gel Permeation Chromatography with Triple Detection

This study presents the possibility of replacing the 1,2,4-trichlorobenzene (TCB) recommended by ASTM D 6474 for the analysis by gel permeation chromatography (GPC) of linear polyethylenes with dibutoxymethane (DBM, butylal), a halogen-free and less toxic solvent. The molecular weight distributions as well as the K and alpha parameters of the Mark-Houwink-Sakurada relationship were measured for polyethylene solutions in TCB and DBM, using a GPC system with triple detection (light scattering, differential refractive index, and viscometer). For commercial metallocene polyethylene resins typically used for film and packaging applications, the GPC method in DBM provided results comparable to those obtained in TCB.     

Characterization of Polypropylene in Dibutoxymethane by High-Temperature Gel Permeation Chromatography with Triple Detection

This study presents the possibility of replacing the 1,2,4-trichlorobenzene (TCB) recommended by ASTM D 6474 for the analysis by gel permeation chromatography (GPC) of polypropylenes with dibutoxymethane (DBM, butylal), a halogen-free and less toxic solvent. The molecular weight distributions as well as the K and alpha parameters of the Mark-Houwink-Sakurada equation were measured for different types of commercial polypropylene samples solubilized in TCB and DBM, using a GPC system with triple detection (light scattering, differential refractive index, and viscometer). For the analyzed resins, covering typical applications of polypropylene, the GPC method in DBM provided results similar to those obtained in TCB.     

GPC法测定塑料粘结炸药中高分子材料的相对分子质量及其分布

采用凝胶渗透色谱法使用示差折光检测器与二极管阵列检测器联用技术,并根据高分子材料在溶剂中的不同溶解能力对塑料粘结炸药中偏氟乙烯-三氟氯乙烯共聚物和苯乙烯-丙烯腈共聚物混合体系进行了分离及相对分子质量测试,获得混合体系中单一组分的相对分子质量及其分布,建立了适合于该混合体系的GPC测定方法。经与原材料的相对分子质量结果比对,证明该方法分离效果良好。     

星形支化聚苯乙烯模型化合物的合成及表征

本文用阴离子聚合方法,首先合成了线形‘活’的聚苯乙烯大分子阴离子,然后用二乙烯基苯为偶联成核剂,制备了十三个4-80臂较窄分子量分布的等臂长规则星形支化聚苯乙烯的模型化合物,并用GPC—粘度计联用装置对之进行了表征。