不同晶型TiO2消光PET的流变性能研究

分别以金红石型二氧化钛(TiO₂)粉体和锐钛矿型TiO₂粉体为消光剂,通过原位聚合制备不同TiO₂粉体含量的消光聚对苯二甲酸乙二醇酯(PET),研究了不同晶型TiO₂消光PET的流变性能。结果表明:在剪切速率()为4000~7000 s^-1,金红石型TiO₂和锐钛型TiO₂消光PET熔体的表观黏度(η_a)随的变化幅度均较小,均具有良好的纺丝稳定性;相同温度下,金红石型TiO₂消光PET的非牛顿指数(n)小于锐钛型TiO₂消光PET,但随着温度升高,金红石型TiO₂消光PET的n上升幅度大,其η_a对变化更为敏感;在常规纺丝条件下,金红石型TiO₂消光PET的黏流活化能(E_η)明显小于锐钛型TiO₂消光PET,TiO₂含量较低时金红石型TiO₂消光PET的η_a对温度变化的敏感程度较小;相同温度下,金红石型TiO₂消光PET熔体的结构黏度指数(η)高于锐钛型TiO₂消光PET;在纺丝温度有波动的情况下,金红石型TiO₂消光PET可纺性好,但其纺丝工艺窗口较窄,应采用更高的纺丝温度以获得良好的纺丝效果。

Study on rheological properties of dull PET with TiO2in different crystal forms

Dull poly(ethylene terephthalate)(PET)with different content of TiO₂powder was prepared by in-situ polymerization using rutile titanium dioxide(TiO₂)powder and anatase TiO₂powder as flatting agent.The rheological properties of dull PET with TiO₂of different crystal forms were studied.The results showed that the apparent viscosity(η_a)of rutile TiO₂and anatase TiO₂dull PET melts changed little with the shear rate()in 4000-7000 s^-1,indicating that the melts both had good spinning stability;the non-Newtonian index(n)of rutile TiO₂dull PET was lower than that of anatase TiO₂dull PET at the same temperature,but increased greatly with the increase of temperature,and itsη_awas more sensitive to;the viscous flow activation energy(E_η)of rutile TiO₂dull PET was significantly lower than that of anatase TiO₂dull PET under the conventional spinning conditions,and theη_aof rutile TiO₂dull PET was less sensitive to the change of temperature when the content of TiO₂was low;the structural viscosity index(η)of rutile TiO₂dull PET melt was higher than that of anatase TiO₂dull PET melt at the same temperature;rutile TiO₂dull PET had fairly good spinnability under the fluctuation of spinning temperature,but the spinning process window was narrow,so the satisfying spinning effect would be acquired by applying higher spinning temperature.