Cox-Merz规则和时温叠加原理在聚合物剪切黏度测量中的应用与研究

摘要

In order to explore the test methods of polymer shear viscosity ,and better improve the production efficiency , the low density polyethylene ( LDPE) was selected to investigate .A series of dynamic rheological tests were conducted by Rotational rheometer ,which include the strain sweep ,frequency sweep .The dynamic testing results were converted into two groups of polymer shear viscosity , through Cox -Merz relation and Time -Temperature superposition , and compared with shear viscosity of the steady flow test .It turned out that the Calculation error of Cox -Merz relation is around 1.7%,shear rate range is 10 -1 ~103 s-1 .It is suitable for shearing viscosity test under high shear rate ,and coordinate with the steady state test results can be a wider range of shear viscosity curve .The calculation error of apply Cox -Merz relation and Time-Temperature superposition at the same time is about 2.3%,with a larger shear rate range ,but the test method is tedious .%为了研究聚合物材料剪切黏度的测试方法，从而更好的改善聚合物产品的加工和生产效率，本文以低密度聚乙烯（ LDPE）为研究对象，应用旋转流变仪对其进行动态测试，包括应变扫描、频率扫描，然后应用Cox-Merz规则和时温叠加原理对动态测试结果进行换算得到两组聚合物剪切黏度结果，并与直接进行稳态流动测试得到的剪切黏度结果进行比较。结果表明： Cox-Merz规则的换算结果误差在1．7％左右，剪切速率范围为10-1～103 s-1，适合于高剪切速率下的剪切黏度测试，与稳态测试结果相配合可得更大范围的剪切黏度曲线；同时应用时温叠加和Cox-Merz公式的结果误差为2．3％左右，剪切速率范围更大，但测试方法繁琐。