用Raman光谱研究碳纤维/聚醚醚酮复合材料的界面结构

用Ｒａｍａｎ光谱研究碳纤维／聚醚醚酮复合材料的界面结构李铁骑章明秋曾汉民（中山大学材料科学研究所聚合物复合材料及功能材料国家教委开放研究实验室广州５１０２７５）关键词界面结构，Ｒａｍａｎ光谱，碳纤维／聚醚醚酮复合材料随着近年来热塑性聚合物的加工...

A STUDY OF INTERFACIAL STRUCTURE IN CARBON FIBER/POLYETHERETHERKETONE COMPOSITES WITH FT-RAMAN SPECTROSCOPY

FT Raman Spectroscopy was used to study the interphasial structure in carbon fiber/polyetheretherketone (CF/PEEK) composites. Spectra of APC 2 laminates with different thermo mechnical histories show a broad band around 1300 cm-1 distinctive either to the A1g scattering of carbon fiber or to PEEK overtones, suggesting different PEEK structure in composites compared to neat resin. To simulate formation of the interphasial structure in the composites, AS4 fiber was coated with PEEK through its chlorophenon solution. The FT Raman study of the coated fibers reveals that the 1300 cm-1 band originates from overlapping of the dispersive branches of graphite A1g and PEEK ring C—O scattering. Comparison of the spectra of coated fibers with those of the melted ones reveals profound effects of melting on interphasial structure. Raman spectra of the unmelted coatings were dominated by E2g and non dispersive A1g branches of graphite and localized modes of PEEK. When melted, the spectra became highly dependent on coaling thichness. When thickness of PEEK layer is about a dozen of nanometer, the broad band around 1600 cm-1 can be found stronger compared to that of unmelted coatings. The band center shifted to lower wavenumber when coating thickness decreased. When the PEEK coating approached the order of nanometer, spectra typical to amorphous and mesophase carbon were found. The results suggest that the structure of the polymer near carbon fiber must be different from that in the bulk if PEEK is allowed to melt. The structure difference is discernible at least on two scales, one identical to the dimension of chain coil and another to thickness of the segments. While structure on the latter scale needs further work to be understood more explicitly, the limited results hinted matching of graphite crystallites with the polymer segments. Within a dozen of nanometers to the fiber surface orientation of the ether ether ketone segments are no doubt stronger than those in neat PEEK. It was thus deducted that interphase forms in composite during processing through interaction of the EEK segments with graphite in short range neighbor to carbon fiber surface and chain orientation within a larger range of tens of nanometers.