Preparation And Study Of Surface Modified Polyacrylonitrile Fiber And Sulfonated Poly (Ether Ether Ketone) Composite Proton Exchange Membrane

The sulfonated polyether ether ketone has the characteristics of high strength and good selective permeability.However,its commercial application is limited by the strength reduction caused by high proton conductivity.It is generally believed that the modified fibers can help to form a continuous proton transport channel in the proton exchange membrane and improve the conductivity and mechanical strength of the proton exchange membrane.Polyacrylonitrile fiber has the characteristics of high strength and easy preparation.The polyacrylonitrile fiber was hydrolyzed and modified to have a hydrophilic carboxyl group on its surface,which can improve its interfacial binding ability with sulfonated polyether ether ketone.Then the surface of polyacrylonitrile fiber was modified to contain amino acids and amino acids,to investigate the different surface state of fiber can influence the performance of the composite membrane.The research contents are as follows:Firstly,the effects of polyacrylonitrile fiber synthesis conditions and modified fibers on composite membranes were investigated.The suitable conditions of electrospinning polyacrylonitrile fiber were investigated and the fiber morphology was observed by SEM.Then,the hydrolysis experiment was carried out to control the hydrolysis temperature,change the concentration and hydrolysis time of the hydrolysis solution,and the appropriate modification conditions were obtained through the comprehensive evaluation of the fiber and the composite membrane.It was found that the higher the fiber content,the stronger the composite membranes,but the lower the conductivity.The degree of fiber hydrolysis increases the conductivity of the fiber but decreases its strength.The proton conductivity along the fiber direction is about 10% higher than that in the vertical test,indicating that the interface between the fiber and sulfonated polyether ether ketone has certain help to proton transmission.Secondly,the effects of amino acid and diamino compounds on the properties of composite membranes were investigated.The surface of polyacrylonitrile fiber was modified by amino acid and diamino compound and the composite membrane was prepared.The experimental results showed that the hydrophobic amino acid performance decreased most seriously,indicating that the hydrophilic and hydrophobic state of the fiber surface had a certain effect on the composite membrane.In diamino compounds,because the molecular chain is relatively neat,its crystallinity is high,and the composite membrane effect after composite grafting is poor.The molecular chain of ethylenediamine is short and the crystallization is poor,and the performance of composite membrane is improved.