Synthesis And Properties Of PPESK-b-PEBED Copolymer

Poly(aryl ether)s are considered as an important class of high performance engineering thermoplatsics due to their excellent physical properties such as high modulus, toughness, high thermal, thermo oxidative stability and chemical resistance. Novel poly(phthalazinone ether sulfone ketone)s (PPESK) synthesized by our group, are a heat resistant poly(aryl ether)s with reasonable solubity containing phthalazinone moiety. However, their high melting viscosity make them hard to process by extruding molding and injection molding.In order to improve the melting processing of PPESK, PPESK-b-PEBEK is successfully synthesized via PPESK oligmer endcapped by phenoxide and PEBEK segment drived from the reaction of biphenyoxide and bis(4-fluorophenyl) ketone. The number-average molecular weight(Mn) of PPESK oligmer is10800and Mn of PEBEK oligmer is3000. Three synthetic routes were investigated. The results in DSC showed that addition of BP first into the reaction system named as step-by-step is selected to synthesize this kind of block copolymers.PPESK-b-PEBEKs were synthesized with different weight contents of PEBEK in PPESK5050series and PPESK8020series respectively. The copolymers obtained with PEBEK segments below to20wt%for PPESK5050-b-PEBEK and below to25wt%for PPESK8020-b-PEBEK, respectively, could be soluble in tetrachloroethane. According to the FTIR spectram, the reaction of PPESK oligmer with-NH chain-ends and PEBEK with the fluorine chain-ends took place. Viscosity measuring of PPESK-b-PEBEK showed that the inherent viscosity of block copolymer decreased with increasing content of PEBEK. PPESK-b-PEBEKs exhibited glass transition temperatures ranging from230℃to280℃and melting temperature around330℃in DSC. Tg increased with the raising content of PEBEK. There was no obvious change of Tm. These block copolymers showed very high thermal stability up to500℃around for5%weight loss and520℃around for10%weight loss under nitrogen in TGA. The crystal peaks of PEBEK in the copolymers were observed in WAXD. DMA results exhibit that the storage modulus of PPESK-b-PEBEK in PPESK8020series is2.5GPa. The HAKKE rheological property tests proved that PPESK-b-PEBEK led to a marked decrease in melt viscosities compared with PPESK indicating that the rheological behaviour of PPESK is improve with the addition of PEBEK.