Studt On Surface Modification Of PET Nonwovens And PET Nonwovens/PVDF Membranes Adhesive Properties

Polyvinylidene fluoride(PVDF)membranes have the advantages of high flux,strong hydrophobicity,easy control of pore structure and pore size distribution,and are widely used in the field of water treatment.In order to enhance the mechanical strength of the PVDF membranes in industrial production,a polyester(PET)nonwovens is often used as a supporting material for the PVDF membranes.However,PET molecules lack strong polar groups and the PET fiber surface is smooth,which results in poor adhesion between the PVDF membrane and the PET.the PVDF membranes are easily peeled off from the surface of the PET during use.Therefore,the utilization of PVDF/PET membranes is affected badly.In this paper,the surface of PET was modified by sandpaper,chemical treatment and surface modification of silane coupling agent.The effects of different modification methods and operating conditions on the surface properties of PET and the interfacial properties of PVDF/PET membranes were investigated.The surface properties of PET nonwovens were characterized by scanning electron microscope,roughness tester,Fourier infrared spectrometer and contact angle meter,the interfacial adhesion of PVDF/PET membranes was characterized by 180° peel strength.This study shows that three PET surface modification methods can effectively improve the interfacial adhesion of PVDF/PET,in which sandpaper treatment can increase the peel strength by 2.6 times,chemical treatment can increase it by 67.6%,and the surface of the coupling agent can improved it by 71.1%.After researching on the interface enhancement mechanism,the sandpaper treatment can enhance the mechanical interlock between the PVDF membrane and PET nonwoven.After chemical treatment,the oxygen content and roughness of the PET fiber are increased,and intermolecular and mechanical forces are enhanced.After the surface modification of silane coupling agent,the silicon alcohol molecular chains were grafted on the surface of PET,the surface roughness,oxygen-containing functional groups and wettability of PET are increased,the mechanical and chemical bonding forces between the interfaces are enhanced,and the flexible deformation layer can effectively resist peeling stress.In this paper,the effects of preparing conditions such as coagulation bath temperature,casting solution temperature and polymer content on the peel strength of PVDF/PET membranes were investigated.The results show that the structure of the PVDF membrane has little effect on the adhesion,compared to the surface modification of the PET reinforcement.