Study On The Preparation And Characterization Of High-performance Poly(Aryl Ether Ketone) Foam

Polymeric foam is widely used in food packaging, lightweight materials, sportsequipment, automotive parts, transportation and other fields due to its advantages oflightweight, excellent sound and thermal insulation, high strength to weight ratio andsaving raw materials. However, in many special application areas, such as electronicpackaging, biomedical materials, aerospace, defense and military, the foam materialsare required to perform high thermostability, great resistance to corrosion, highmechanical strength and high dimensional stability performance, so the developmentof polymeric foams from high-performance thermoplastics become a hot area ofresearch.Poly（aryl ether ketone） has great thermostability and mechanical strengthbecause of the fully aromatic structure on the main chain and the intermolecularconjugated Ï€ bond, and is considered as one of the most promising highperformance engineering thermoplastics. However, so far there is no commercializedfoam products produced from poly（aryl ether ketone）, the reason is mainly due to therelative difficulty processing technology.In this thesis, three microcellular foam processing technology, which are rapidheating batch foaming technology, pressure quenching batch foaming technology andcontinuous foam extrusion technology, were used to investigate the mechanism andfoaming behavior of amorphous and semi-crystalline poly（aryl ether ketone）ssystematically.First, we chose the amorphous poly（aryl ether ketone） as the research object andrapid heating as batch foaming method so as to have better understanding of the foaming mechanism due to the fact of that the operation is easy to control. Variouscontent of adamantyl groups were introduced into polymer matrix by moleculardesign, aiming to study the effect of large pendant group on the foaming behavior ofamorphous poly（aryl ether ketone）. The gas adsorption test results showed that theintroduction of adamantyl group played a positive role on increasing free volume inthe polymer matrix and consequently enhanced the solubility of CO₂in the matrix,thus further affected the cell structure. The effects of processing parameters on the cellmorphology were investigated. By optimizing the processing parameters, a series ofsupermicrocellular poly（aryl ether ketone） foams with a size of200-500nm wereprepared.In order to further broaden the application area of poly（aryl ether ketone）, weswitch our research object to semi-crystalline poly（ether ether ketone）, because it hashigher thermal and mechanical performance. The pressure quenching foaming methodwas used in the chapter. High pressure DSC and DSC were used investigate to doublemelting peak behavior of poly（ether ether ketone） with and without CO₂,respectively.The effects of processing parameters were investigated and a detailed analysis of therole of a crystalline in the control of nucleation and cell growth was conducted. Aseries of poly（ether ether ketone） foamed beads were successfully prepared with thecell size of8⁴00μm and the expansion ratio of7to16.Thanks to the aforementioned work, we have better understanding of the foamability and foaming behavior of poly（aryl ether ketone）, and we finally develop acontinuous extrusion foaming technology for semi-crystalline poly（ether ether ketone）.The effects of processing parameters, die geometry, temperature profile andnucleating agents on the cell density and expansion ratio were investigated.