碳纤维增强聚醚醚酮的非等温结晶行为与力学性能

利用聚酰亚胺(PI)作为碳纤维(CF)界面改性剂,制备了界面改性碳纤维增强聚醚醚酮(MCF/PEEK)复合材料。采用差示扫描量热仪(DSC)讨论了CF及其界面改性对PEEK非等温结晶行为的影响机制与作用规律,并基于莫志深法研究了MCF/PEEK的非等温结晶动力学;借助DSC和小角X射线散射仪(SAXS)表征不同降温速率下PEEK基体的结晶结构,采用万能试验机评价了MCF/PEEK的力学性能。结果发现:CF对PEEK的结晶有较为明显的异相成核促进作用,经过PI界面改性之后成核作用有所下降,但结晶行为仍较纯PEEK更容易发生,整体结晶速率更快;随冷却速率的增大,基体结晶度、片晶厚度与长周期均减小,MCF/PEEK的拉伸强度与模量也显著减小,层间断裂韧性提高。

Non-Isothermal Crystallization Behavior and Mechanical Properties of Carbon Fiber Reinforced Polyetheretherketone Composites Based on Interfacial Modifications

Polyimide(PI) was used as interface modifier of carbon fiber(CF) to prepare interfacial modified carbon fiber reinforced polyetheretherketone(MCF/PEEK) composites. The effects of CF and its interfacial modification on the non-isothermal crystallization behavior of PEEK were discussed by differential scanning calorimetry(DSC). And the non-isothermal crystallization kinetics of MCF/PEEK was studied based on Mo method. The crystal structure of PEEK matrix at different cooling rates was characterized by DSC and small angle X-ray scattering(SAXS). Besides, the mechanical properties of MCF/PEEK were evaluated by universal testing machine. It is found that CF has obvious heterogeneous nucleation promoting effect on the crystallization of PEEK. The nucleation effect is decreased after interfacial modification by PI,but the crystallization behavior is still easier to occur than pure PEEK, and the overall crystallization rate is faster. With the increase of cooling rate, the crystallinity, lamella thickness and long period of the matrix are decreased, the tensile strength and modulus of MCF/PEEK are also decreased significantly, but the mode I critical strain energy release rate is improved.