Abstract

Rheological measurements of polyethylene solutions in a novel nontoxic solvent were used to determine the Mark-Houwink parameters for PE of widely different molecular weights to assess the viscosity average molar mass for PE of several millions of g.mol⁻¹. Solutions of high density polyethylene that had been previously characterized by size exclusion chromatography were prepared in a harmless naphthenic oil. The intrinsic viscosities were obtained by varying the concentrations of the different calibration samples solutions using a rotational rheometer equipped with a Couette cell. The intrinsic viscosities were determined by both Huggins and Kraemer descriptions of the viscosity variations with concentration. Subsequently, a calibration curve of intrinsic viscosities versus the molar mass was plotted, and the parameters of the Mark-Houwink-Sakurada equation were obtained for polyethylene in naphthenic oil. Using this equation and the newly estimated parameters, the viscosity average molar mass of a high molar mass polyethylene and a commercial ultra high molar mass polyethylene were been determined by measuring their respective intrinsic viscosities. Finally, the method has been validated by comparing these results to values obtained by standard viscosimetry in 1,2,4-trichlorobenzene and to the values given by the supplier, obtained by other methods.

摘要

聚乙烯溶液在新型无毒溶剂中的流变测量用于确定分子量差异很大的 PE 的 Mark-Houwink 参数，以评估数百万 g.mol ^{-1 的}PE 的粘均摩尔质量. 先前已通过尺寸排阻色谱表征的高密度聚乙烯溶液在无害环烷油中制备。特性粘度是通过使用配备 Couette 池的旋转流变仪改变不同校准样品溶液的浓度来获得的。特性粘度由 Huggins 和 Kraemer 对粘度随浓度变化的描述确定。随后，绘制了特性粘度与摩尔质量的校准曲线，并获得了环烷油中聚乙烯的 Mark-Houwink-Sakurada 方程的参数。使用这个方程和新估计的参数，高摩尔质量聚乙烯和市售超高摩尔质量聚乙烯的粘均摩尔质量通过测量它们各自的特性粘度来确定。最后，通过将这些结果与在 1,2,4-三氯苯中通过标准粘度测定法获得的值以及供应商提供的通过其他方法获得的值进行比较，对该方法进行了验证。