PC/PET共混物的非晶相取向与动态黏弹性能研究

Study on Amorphous Phase Orientation and Dynamic Viscoelasticity of PC/PET Blends

通过广角X射线衍射（WAXD）和动态力学性能（DMA）测试研究了130℃高温拉伸聚碳酸酯/聚对苯二甲酸乙二醇酯（PC/PET）合金的非晶相分子取向与黏弹性的关系。从微观结构决定宏观性能的观点出发,验证了聚合物制品取向态与储能模量、损耗模量之间的关系。根据DMA温度扫描模式下储能模量和损耗模量曲线的物理意义,分别提取共混试样玻璃态时储能模量平台区的末端和高弹态时损耗模量峰值作为与取向比较的参考值。获得的动态黏弹性的取向依赖关系与纯PC试样进行了比较,均近似符合e指数规律。储能模量随非晶区域分子取向的增加而提高,且随着PET用量的增加,储能模量增速降低。损耗模量与取向也显示出相似的递增关系,却并未明显受到PET用量的影响。由此结果讨论了富含PC的共混试样中非晶区域分子取向对黏弹性能影响的机理,以及不同PET用量对分子取向行为的影响。实验通过对不同取向态的对比,近似获得了取向结构发展中结构性能的动态联系。为研究和控制PC/PET合金性能,进一步了解PC分子取向的机理提供了新思路。

The wide angle x-ray diffraction（WAXD） and dynamic mechanical analysis（DMA） were used in probing the relationship between molecular orientation and viscoelasticity of stretched polycarbonate（PC）-Polyethylene terephthalate（PET） blend samples at 130℃. Based on the recognition of structure determines properties, the experiments proved the assumption about relationship between oriented state and storage modulus, as well as oriented state and loss modulus. According to the molecular interpretation about storage and loss modulustemperature curve in temperature sweep mode in DMA, the storage modulus value at the end of the glassy state plateau and the loss modulus peak in the rubbery state temperature range were chosen to establish relationship with orientation. The orientation dependence of dynamic viscoelasticity of blend samples has a similar regularity with e-exponential as pure PC samples. The storage modulus increases with the increasing molecular orientation in amorphous region, while the increment rate of storage modulus decreases with the increase of PET content. The loss modulus and orientation also show a similar increasing relationship, but it is not obviously affected by the amount of PET. According to the experimental results, the mechanism of the viscoelasticity changes with orientation in amorphous region of rich-PC blend was discussed, as well as the influence of PET content on the orientation. Through comparing the dynamic mechanical parameters in different oriented states, an analogue image about the connection between microstructure and viscoelasticity during orientation evolution is obtained. It provides a new idea for studying and controlling the properties of PC/PET alloy and further understanding the mechanism of PC molecular orientation.