冷态模型系统糖浆溶液模拟PET熔体可行性分析

Feasibility analysis of using syrup solution as simulation medium for PET melt in cold model system

利用旋转流变仪和毛细管流变仪研究了聚对苯二甲酸乙二醇酯(PET)和糖浆溶液的流变行为及黏弹行为,通过对PET熔体和糖浆溶液在线性粘弹区、本构方程、维森伯格(Wi)数及挤出胀大等方面的分析,研究了冷态模型系统中模拟介质糖浆溶液模拟PET熔体的可行性。结果表明:PET的线性粘弹区和糖浆溶液相似,且应力临界值(τc)大于等于1 000 Pa;通过调节糖浆溶液的含水量使之与某一温度下的PET熔体在一定剪切速率范围内具备大概一致的流动曲线,在牛顿流体拟合和Cross拟合范围上,两者具有高度相似性;在储能模量、损耗模量、Wi数及挤出胀大比等方面,PET熔体和经过调节的糖浆溶液具有一定的规律相似性;可通过除去水分、添加一定量的聚丙烯酰胺使糖浆溶液的黏度和弹性在一定的剪切速率范围内与PET熔体具备一致或者相似的变化规律;证实了糖浆溶液作为冷态模型系统模拟介质的可行性。

The rheological behavior and viscoelasticity of polyethylene terephthalate （PET） and syrup solution were studied by rotary rheometer and capillary rheometer.The syrup solution and PET melt were compared and analyzed from the aspects of linear viscoelastic region,constitutive equation,Weissenberg（Wi） number and extrusion swell behavior.The feasibility of using syrup solution as simulation medium for PET melt was studied in cold model system.The results showed that PET melt had the similar linear viscoelastic region to syrup solution and critical stress （τc） not less than 1 000 Pa; the syrup solution had almost the same flow curve with PET melt within a certain shearing rate range at a specific temperature by regulating the water content of syrup solution; they were of high similarity in Newtonian fluid fitting and Cross fitting results ; PET melt had a regular similarity with formulated syrup solution in storage modulus,loss modulus,Wi number and extrusion swell ratio; the viscosity and elasticity of syrup solution could be of the same or similar change regularity with PET melt within a certain shearing rate range by eliminating different amount of water and adding a certain amount of polyacrylamide,which proved the feasibility of using syrup solution as simulation medium for PET melt in cold model system.