The Study Of PU/PP Multilayer Filter Membrane Based On PP Needle Felt

Composites have the advantage that the single material incomparable, which will be thedeveloping trend of filter materials in current and future. Polypropylene (PP) needle felt as thefilter material has good physicochemical property and vast potential for future application. Butonly by compound polymer could make it applying to the precision filter. Based on mastering themethod of polyurethane (PU) synthesis and pore-forming, further treatment of composite withthe PP needle felt will be taken. Through the way of laminating and coating, the PU/PPMultilayer filter membrane is obtained. Furthermore, the properties of that had also beenconducted a preliminary study.The fabrication and properties of PU membrane showed that the dosage of chain extenderhas large effect on PU emulsion and PU membrane. When the molar ratio of BDO and PTMG is3:1, PU membrane would reach a low contact angle, but the viscosity increased to3452.08m Pas, and the tensile properties of polyurethane film also reached the maximum. Ethylene glycolcan make the PU membrane has high porosity, moisture permeability, and tensile properties. Bymixing polyethylene glycol-200with ethylene glycol as the porogen, the moisture permeabilityof PU membrane increase to4707.8g/(m2d), and the contact angle also has a certainimprovement with a small degree.By using dry or wet method and laminating or coating composite way,4kinds of PU/PPmultilayer filter membrane have been made. The result revealed that laminated filter membranehas homogeneous surface, and dry method had led to the interconnection between holes, highsurface porosity and better wettability. Besides the capillary effect of PP needled felt makePU/PP multilayer filter membrane also presents good conductivity, but it would be significantlydecreased with the increase of the thickness. Laminated filter membrane possessed high waterflux, which could be2729L/(m2h). Due to the small bonding force between PU and PP, PUmembrane could not reinforce the PP needle felt, the mechanical properties of compoundmembrane mainly depends on the mechanical properties of needled felt itself.The surface morphology of coating filter membrane was more rough, and its pore wassmaller, fewer, wettability was also relatively poor. In addition, the polyurethane emulsionpermeated the PP needled felt, occupied the space between the PP fiber, weakening the hydraulic conductivity of PP needled felt. It also indirectly affected the PU/PP multilayer filter membranewater permeability, whose maximum water flux was only382.17L/(m2h). However the coatingmethod could strengthen the binding force of the interface between PU and PP, thus improve thePU/PP multilayer filter membrane mechanical strength.