The Properties And Preparation Of Microcellular Foams Based On Poly(Phthalazinone Ether Sulfone Ketone)Containing Biphenyl Moieties

Reducing weight and improving performance of materials have always been a goal pursued by the industry.The foaming of materials can significantly broaden its application in engineering.Poly(phthalazinone ether sulfone ketone)containing biphenyl moieties(PPBESK)is a novel high-performance polymer that possesses patent of china,has extremely high glass transition temperature(Tg>200 ?),excellent thermo-oxidative stability,superior mechanical properties,and can be applied in aerospace,automotive and military sectors widely.As a result,PPBESK has become an ideal materials to replace the metal parts and realize system weight reduction.At present,there are many researches on the synthesis,the preparation of composites and performance of PPBESK.However,no research on foams based on PPBESK exists.In order to obtain high performance PPBESK foams,we studied the preparation of PPBESK foams using supercritical fluids foaming techonology,and discussed the foaming process,the regulation mechanism between cell structure and properties of foams.In this paper,PPBESK foams were prepared by batch foaming with supercritical CO2,and their foaming behaviors were studied in detail.The essential factors leading to the the transition of the open-close cell structure in the supercritical fluid foaming system were obtained.The foaming window of PPBESK reisn was obtained.The relationship among the foaming temperature,saturated pressure,mass density of foams and the cell structure was determined.Achieved accurate control of open-closed cell structure.Secondly,the effects of fumed silica(R812s)and hydroxylated multi-walled carbon nanotubes(MWCNT-OH)as heterogeneous nucleating agents on the foaming behavior and cell strucuture of PPBESK were studied.The results show that both of them can play a very good role in heterogeneous nucleation,the foams has excellent thermal stability properties,broaden the scope of expansion.Compared with R812s,the MWCNT-OH can provide channels for the diffusion of CO2,and can improve the production efficiency of foams in industry.Finally,the supercritical microporous injection molding method was used to obtain three-dimensional foamed articles based on PPBESK resin.The problem was that PPBESK has high melt viscosity and could not be directly subjected to supercritical microcellular injection molding.In order to decrease the melt viscosity of PPBESK,polyphenylene sulfide(PPS)was added to the PPBESK and the rheological behavior,phase behavior,interface force between two phase,mechanical property and cell structure of PPS/PPBESK blend system were studied in detail.The results show that the addition of PPS can significantly reduce the melt viscosity of PPBESK,improve its processing fluidity,and is conducive to the formation of gas nucleus and the growth of bubbles during the foaming process.At the same time,although PPS/PPBESK is a partially compatible system,the two-phase diffusion is better and the bond strength is higher.Moreover,the addition of PPS does not result in the loss of the mechanical and thermal stability of PPBESK.And the resulting microporous material has uniform cell distribution.The average cell diameter were 17.7 ?m and cell density were 4.78×109 cells/cm3,respectively.Moreover,the impact strength of foams is 1.75 times than that of the unexpanded material of the same component,and the specific strength is higher than that of the same component.