Adjustment Of The Structure Of Polyphenylene Sulfide And Its Application In Separation Membranes

In recent years,with the development of the membrane field,polyphenylene sulfide(PPS)microporous membranes have been widely used in membrane separation fields under special environments due to their excellent properties such as high temperature and corrosion resistance.However,due to its own defects(poor mechanical properties,easy oxidation,high melting point,non-ultraviolet resistance,easy aging,non-antibacterial,etc.)it also limits its wider application in the field of membranes.In the conventional physical blending modification,the modified group is easy to fall off during the membrane separation process,which leads to the degradation of membrane performance and membrane life.Therefore,the study of regulating PPS body and its membrane properties from the perspective of molecular structure has important research significance and application value for the development of membrane materials in special environments.In this paper,the PPS bulk structure is regulated from a molecular perspective,and a multi-stage thermal oxidation crosslinking modified PPS membrane material method is proposed.The polyphenylene sulfide resin was thermally oxidized and crosslinked at 200-260? in the air atmosphere.Characterization methods such as FTIR were used to determine the new groups generated during the thermal oxidative crosslinking process.The thermal oxidative crosslinking process was systematically performed.Studies have shown that PPS is desulfurized and crosslinked at high temperatures.Under the optimal conditions,the thermally oxidized PPS film prepared by the method has a retention rate of 98% on BSA and a water flux of up to 96.37 LMH.The PPS microporous membrane was also subjected to interface thermal oxidation at 200-260?.Then the structure was characterized by XPS,SEM and other methods,and the effect of oxidation parameters on the membrane performance was studied.The results show that when PPS microporous membranes undergo secondary porosity under high temperature air,the membrane flux is significantly increased and the contact angle Significantly reduced.Under the optimal conditions,the water flux is as high as 129 LMH,and the retention effect of BSA remains unchanged at 62%.The retention rate after carbon ink is 80%.A preliminary study of the modification mechanism was performed by FTIR and XPS.Under thermal oxidation,the residual benzophenone volatilization induced secondary pore formation,and at the same time,the upper surface of the membrane was cross-linked to form hydrophilic groups,which improved hydrophilic properties.In order to investigate the effect of PPS molecular structure on the performance of the separation membrane,a non-linear low-melting polyphenylene sulfide(L-PPS)resin was prepared by changing the sodium sulfide method,and the synthesized LPPS was characterized by TG,DSC and FTIR,XRD.Then,L-PPS microporous membrane was prepared by thermally induced phase formation.The effect of weight percentage on the morphology,structure and performance of L-PPS membrane was investigated systematically.With the increase of the weight percentage of the polymer,the structure of the L-PPS membrane changes,the mechanical properties significantly increase,the permeability decreases,and the separation performance improves slightly.