Synthesis And Properties Of PEEK Terpolymer Containing Branched Units

Poly(ether ether ketone)(PEEK) are a class of well-known high temperature resistant aromatic polymer with semicrystalline nature, possessing outstanding properties such as good thermooxidative stability, chemical resistance, high abrasive resistance, and radiation resistance, thus it have wide application in aerospace, electrical and electronic fields, transportation, medical field etc. Currently, researches on PEEK have been deep in developed country. Meanwhile, commercial process for PEEK is already available in domestic, however, several problems remains:PEEK is still poor in color, amount of grades is few, cannot produce high value-added PEEK resin and so on. So researches and development for PEEK are still in need.This paper describes a synthetic route for4,4’-difluoro-diphenylmethanone, with4-fluorobenzoyl chloride and fluorobenzene as reactant. The effects of reactant ratio, catalyst amount, reaction temperature and time on the yield are investigated. We improved the purification process for the product and NMR, FT-IR spectroscopy, melting point test are used for characterization of structure and purity determination. As the results depict, the best conditions for the maximum crude yield, which is96.6%, are as follows:the mole ratio of AICl3, LiCl and4-fluorobenzoyl chloride is2.9:1.45:1; mole ratio of fluorobenzene and4-fluorobenzoyl chloride is1.6:1; the reaction time and temperature are set as180min and0℃relatively. The process for purification is carried out in a reduce pressure condition, the temperature is145℃and degree of vacuum is0.1. The final yield of4,4’-difluoro diphenylmethanone is85.7%and melting point is109-111℃.We designed and synthetized a novel B3type monomer, benzene-1,3,5-triyltris ((4-fluorophenyl)methanone). The reactants are1,3,5-benzenetricarbonyl trichloride and fluorobenzene. Influence of reactant ratio, catalyst amount, reaction temperature and time on the yield is discussed in detail and structure of this reaction to attain a maximum of yield,80.1%, are concluded as follows:the mole ratio of AICl3, LiCl and1,3,5-benzenetricarbonyl trichloride was1.8:1; the reaction time is360min and suitable temperature is0℃.Using benzene-1,3,5-triyltris((4-fluorophenyl)methanone) and4,4’-difluoro diphenylm ethanone as activated aryl dihalo monomers,1,4-dihydroxybenzene and biphenyl-4.4’-diol as bisphenol monomer, we prepared two kinds of terpolymer(PEEK) containing branched units. The structure, thermal properties, crystalline structure and solubility of the obtained multipolymers are characterized by FT-IR spectroscopy, DSC, TGA, XRD analysis. The terpolymer can only dissolved in concentrated sulfuric acid. All synthetized PEEKs are crystalline and the crystallinity decreased by the raise of branching. Polymer of4,4’-dihydroxybiphenyl benzene, DFPB and1,3,5-triyltris((4-fluorophenyl)methanone) and (the mole ratio is21:21:1) have glass transition temperatures (Tg) of216℃, Tm of335℃, Td5%of543℃, Ta10%of552℃, and the char yield is recorded as52.28%. For comparison, the1,4-dihydroxybenzene is replaced by4,4’-dihydroxybiphenyl (the mole ratio is21:21:1), the resulting polymer (the mole ratio is15:15:1) have glass transition temperatures (Tg) of182℃, Td5%of538℃, Td10%of546℃, and the value for char yield is55.97%.