Control of heat-deformation properties at high temperature of carbon fiber reinforced PEEK by crystallization

本研究的主要目的是开发一种具有高耐热性的聚合物复合材料。聚醚酮（PEEK）是众所周知的超级工程塑料，它具有高强度和高耐热的机械性能。PEEK的CFRP在高温条件下表现出非常高的性能。但这逃脱不了粘弹性变形。在这个项目中，我们试图通过结晶现象来控制和减少蠕变。DSC测试发现，淬火后PEEK的结晶度最小为24%，最大结晶度可达42%。制备了两种PEEK的CFRP。它们是层压材料，是准各向同性材料；[0, 90, 45， -45]s和注塑成型CFRP。纤维重量等级分别为60%和20%。研究了弯曲蠕变现象，并测量了80 ~ 150℃的蠕变柔度。对于CFRP层压板，两种结晶度；分别制备了24和42%，结晶度分别为34%、38%和42%。层压板的最小结晶度小于注塑成型CFRP。测量了各温度下的蠕变柔度曲线，并将其向水平方向移动，直至完全重叠，绘制出蠕变柔度曲线的主曲线。移动的量被绘制在阿伦尼乌斯式的图上。对于所有材料，移位因子都是一条直线。得出蠕变变形服从时间-温度叠加的结论。所有材料均表现出线性粘弹性变形。结晶度增大，蠕变变形减小。最后，得出了通过结晶处理可以控制高温蠕变的结论。

Main purpose of this research is to develop a polymeric composite having high heat resistance. Polyether-ether Keton (PEEK) is well known as super-engineering plastic and this polymer has high strength and high heat resistance on mechanical properties. CFRP of PEEK shows very high performance at high temperature condition. But this can not escape from a visco-elastic deformation. In this project, we tried to control and to decrease the creep deformation by crystallization phenomena.It was found that PEEK had minimum crystallinity 24% just after Quenching and maximum crystallinity could rise up to 42% by DSC test. Two kinds of CFRP of PEEK were prepared. They were laminates, which were quasi-isotropic material ; [0, 90, 45, -45]s and injection molded CFRP. The fiber weight factions were 60% and 20% respectively. We researched bending creep phenomena and measured creep compliance at 80 to 150℃. For CFRP laminate, two crystallinities ; 24 and 42% were prepared and the crystallinities for injection-molded CFRP were 34%, 38% and 42%. The minimum crystallinity of laminates was smaller than injection molded CFRP. Creep compliance curves on each temperature were measured and a master curve of them was drawn by shifting them to horizontal direction until completely over-lap on each other. And the amount of the shifting was plotted on an Arrhenius type figure. For all materials, shift factor made a straight line. We concluded creep deformation was obeyed by the time temperature superposition. And all material shows the linear visco-elastic deformations. And increasing crystallinity, creep deformation was decreased. Finally, from these facts, we concluded that we can control the creep deformation at high temperature by crystallization treatment.