Preparation And Mechanical Properties Of Zein/Polylactic Acid Composite Nanofibrous Membranes

This part of research is co-electrospun of zein and polylactic acid (PLA). The morphologyand structure of the membranes, hydrophilic performance, uniaxial and biaxial mechanicalproperties was studied with different weight ratio. The results showed that fiber diameter becamelarger and showed bad hydrophilic with the increasing of PLA content and solution was easierelectrospinning. Mechanical properties was significantly improved while tensile strength andelongation at break of membranes were increased by74%and68%. But there was no interactionbetween zein and PLA. Compared with uniaxial mechanical behavior, tensile strength andelongation at break of biaxial mechanical behavior was significantly reduced. Tensile strengthwas greater than direct tensile after several cycles. Hysteresis loop was reduced with highcontent PLA.Zein-PLA core-shell fiber membranes was prepared using coaxial spinneret. Themorphology and structure of the membrane, hydrophilic performance, uniaxial and biaxialmechanical properties was studied with different shell flow rate. The results showed that thefiber diameter became larger with the increasing of the shell flow rate. Fibers showed obviousuniform distribution of core-shell structure. Fiber membranes showed good hydrophilic. Themechanical properties was decreased. The hysteresis loop of fiber membranes was decreasedafter several cycles. The biaxial tensile strength was reduced with increasing of shell flow rate.When the flow rate was0.008mL/min, loading tensile strength was increased after several cycles.the curves of circumferential and axial was separated seriously. The tensile strength was reducedafter several cycles and the separation of the curves of circumferential and axial was not soseriously with increasing of shell flow rate.Finally, on the basis of the co-electrospinning and the coaxial electrospinning, zein/PLA(50/50) and zein-PLA (shell flow rate0.01mL/min) were selected to prepare aligned fiber bydrum. It mainly focused on how drum speed affected mechanical properties of fiber membranes. With the increasing of drum speed, fiber diameter reduced from570nm to364nn. And fiberaligned along the direction of rotation. Circumferential tensile strength increased with higherspeed, but elongation at break decreased. While axial tensile strength decreased and theelongation at break increased. The differences of mechanical behavior between circumferentialand axial became seriously with the high drum speed. Circumferential tensile strength increasedand elongation at break decreased. The hysteresis loop of fiber membranes was decreased afterseveral cycles. In the core-shell fiber membranes, the fiber was in orderly arrangement with thehigh speed. With higher speed, tensile strength of circumferential increased and the elongation atbreak decreased. While tensile strength of axial decreased and the elongation at break increased.Tensile strength of circumferential was4times larger than axial. Differences of mechanicalbehavior between circumferential and axial were greater. Fiber membranes has some damageafter several cycles, leading to the tensile strength reduced. In the course of cyclic loading, withthe increase in load times, hysteresis loop became smaller with the increasing of cycles.Differences of mechanical behavior between circumferential and axial were greater.