Preparation And Characterization Of Acrylonitrile-methyl Acrylate Copolymer Microporous Membrane

Polyacrylonitrile(PAN)possesses excellent resistance to inert solvents and bacterial corrosion,heat and physicochemical stability.It has become one of the widely used polymer film materials.At present,most of PAN membranes are prepared by traditional nonsolvent induced phase separation(NIPS)process due to its special structure.Large amounts of polar solvents are needed in the NIPS,resulting in waste of resources and environmental pollution.Besides,the resulting membranes exhibits poorer mechanical properties.Compared with the conventional NIPS process,the structures of membrane formed by thermally induced phase separation(TIPS)are easy to be adjusted and the mechanical properties of the microporous membranes are more excellent.Usually,a single diluent is used in the traditional TIPS method,while,the compatibility of binary system between the single diluent and polymer is fixed.However,the change of compatibility has a significant effect on the structure and properties of the microporous membrane.Therefore,in this paper,two kinds of compounding diluent systems of ethylene carbonate(EC)and triethylene glycol diacetate(TEGDA),sulfolane(TMS)and diphenyl carbonate(DPC)were used respectively.The interaction between mixing dilents with the AN-MA copolymer could be adjusted by changing the proportion of the mixing diluent.The pure PAN membrane is brittle and poor practical.A comonomer methyl acrylate(MA)was used as a flexible monomer to copolymerize with acrylonitrile(AN)to weaken the polar interation.The melt processable poly(acrylonitrile-co-methyl acrylate)(AN-MA)was used as a matrix to prepare AN-MA microporous membranes by TIPS.In this paper,the effects of copolymer content,mixing diluent ratio and additive content on the structure and properties of the microporous membrane were investigated by introducing the sol-gel process.The effects of the molding temperature,the copolymer content,the ratio of the mixing diluent and the additives content on the microstructure and properties of the microporous membrane were investigated in detail.The results showed that:It is shown that the water flux will be improved dramatically when the EC content was reduced,the concentration of AN-MA copolymer was reduced or the content of tetraethyl orthosilicate(TEOS)was increased.The water flux of the AN-MA microporous membrane was up to the maxmum value of 120 L/(m2h)when the EC content was 60 wt.%,the polymer concentration was 9 wt.%and the TEOS content was 5 wt.%.In this paper,80/20AN-MA copolymer microporous membrane containing hydroxylated carbon nanotubes(MWNTs-OH)or nerchinskite(HNTs)was prepared by TIPS method.The AN-MA porous membranes with tubular pores and cellular pores were obtained by changing the type of the compound diluents.When MWNTs 1 wt.%of MWNTs-OH was added,the pure water flux of the microporous membrane was 563.7 L/(m2h),and the rejection was 96.1%.And when HNTs 0.5 wt.%was added,the maximum water flux was 665.7 L/(m2h),and the rejection was 92%.The strength at break and the flexibility of the microporous film increase with the increase of the content of additives in the casting liquid system.When 3 wt.%of MWNTs-OH was incorporated,the breaking strength of the microporous membrane was 3.7 MPa and the elongation at break was 10%.When 1 wt.%of HNTs was incorporated,the breaking strength of the microporous membrane was 2.6 MPa,and the elongation at break was 6%.