Preparation And Modification Of Electrostatic Spinning Cottonseed Protein/Polyvinyl Alcohol Nanofiber Membrane Materials

Our country is rich in cotton production,and the annual yield of cottonseed can reach about 5 million tons.Cottonseed protein(CP)is a kind of low-cost,renewable and biodegradable plant protein.Most CPS are used for fattening and feeding,which greatly wastes the protein resource CP.CP is a biological protein with certain biocompatibility.If CP is fully utilized and prepared into medical materials or cosmetics,the added value of CP can be greatly improved and huge social and economic benefits can be generated.The concentrated CP solution with mass fraction of 3.8% was prepared by alkali dissolution and mixed with polyvinyl alcohol(PVA)solution with mass fraction of14%.The external technological parameters of preparing CP/PVA nanofiber membrane were studied by using the mixed solution with mass ratio CP:PVA=2:8.The spinning process was as follows: the ratio of solute to spinning solution was CP:PVA= 2:8,the spinning voltage was 20 k V(-2 KV-18 k V),the speed of receiving drum was 100 r/min,the distance between drum and syringe tip was 14 cm,the translation stroke was 40 mm,the translation speed was 200 mm/min,the injection speed was 0.06 mm/min,the temperature was 30 ℃,and the humidity was 30 %RH.After discussing the spinning process parameters,the physical and chemical properties of solutions with different CP/PVA quality ratios and their effects on the microstructure,chemical structure,thermal stability and mechanical properties of the prepared nanofiber membrane were investigated.SEM showed that the physical and chemical properties of the mixed solution were important factors affecting the microstructure and diameter distribution of the nanofiber membrane,and the micromorphology and diameter distribution of the prepared nanofiber membrane were correlated with various physical and chemical properties of the mixed solution.FTIR and XRD results showed that the preparation of CP in CP/PVA nanofibers membrane and PVA has certain compatibility,no obvious chemical reaction between molecular,but has formed a certain amount of hydrogen bonding,molecular reaction between components,the successful preparation of blend solution out of the CP/PVA nanofibers membrane,show that PVA addition can improve the spinnability of CP.TG and DSC results showed that the addition of CP could improve the thermal stability of nanofiber membrane,but the thermal stability of nanofiber membrane decreased with the increase of CP,and the thermal stability of protein nanofiber membrane was the best when the addition of CP was 5%.Thetensile strength and elongation at break of the membrane first increased and then decreased with the increase of CP,which may be caused by the poor compatibility between CP and PVA,and phase separation occurred with the increase of CP content in the later stage.When CP was added at 5%,the elongation at break of nanofiber membrane could reach 94.83%,and when CP was added at 10%,the tensile strength could reach 5.08 mpa.In order to make the prepared CP/PVA nanofiber membrane be applied in the medical field and cosmetics,the properties of water resistance and poor mechanical properties of the membrane need to be solved.In this paper,glutaraldehyde was used as a cross-linking agent to cross-link the prepared CP/PVA nanofiber membrane.Studies have found that glutaraldehyde can cross-link CP molecules,CP and PVA molecules,and PVA and PVA molecules to increase the molecular chain.To some extent,the fiber diameter of CP/PVA nanofiber membrane can be increased,and its crystallinity,thermal stability,water resistance and mechanical properties are improved.However,the use and addition of excessive crosslinking agent will have side effects on the comprehensive properties of the membrane,the crystallinity,thermal stability and mechanical properties of the film are reduced.so the amount of crosslinking agent should be controlled within a certain range.