Study On Preparation And Properties Of Enzyme Modified Protein And Cellulose Blend Fiber

Regenerated fiber is made from natural polymers such as protein and cellulose after chemical processing.The emergence of regenerated fibers not only alleviates the dependence on petroleum resources,but also relieves the pressure of environmental pollution.However,formaldehyde will be used to crosslink the regenerated fiber in the production process,and the use of formaldehyde will also pollute the environment.Therefore,we try to modify the protein by enzyme to form polymer.Spinning materials are polymer compounds.In the post-treatment of modified fiber,formaldehyde cannot be used for treatment,to achieve real green environmental protection.Soybean protein isolate(SPI)and casein can form macromolecular polymers after enzyme modification and increase the mechanical properties of the fiber after enzyme modification.In this study,we analyzed the factors that may affect the enzyme reaction.The changes of molecular size,molecular structure,surface hydrop Hobicity and solution viscosity of SPI after crosslinking were analyzed experimentally.It was found that the crosslinking of SPI after acid precipitation was better than that after alkali dissolution in the process of protein extraction.The addition of macromolecule compounds had no effect on the enzyme reaction.Stirring will speed up the enzyme reaction.The loss of basic subunit B of crosslinked SPI was more after acid precipitation.The molecular weight of SPI increased after crosslinking.The viscosity of crosslinked SPI solution is much higher than that of SPI solution.The hydrop Hobicity of SPI increased after crosslinking.The existence of high concentration urea destroys the secondary structure of SPI,makes the globulin structure of SPI loose and the molecular chain open.The viscosity of high concentration SPI solution increased gradually and then decreased with the prolongation of crosslinking time.The viscosity of crosslinked SPI solution decreased at first and then increased with the increase of p H.With the increase of the concentration of CSPI in the spinning solution,the spinnability of the fiber becomes better.However,CSPI fiber becomes brittle and easy to break after drying,and the fiber performance is poor,so the spinning test of CSPI alone cannot be carried out.The softness of the fiber decreased with the increase of protein content.For the two preparation methods of the blend fiber,For the two preparation methods of blend fiber,the first method is to crosslink SPI to form CSPI,and then mix with CMC-Na to prepare spinning solution.Another method is to mix SPI with CMC-Na and then add protease to cross-link to prepare spinning solution.The softness and breaking strength of the fibers prepared by the first method are excellent after drying,and the second method is superior to the second method.When the concentration of CSPI is 4% and the concentration of CMC-Na is 1%,the maximum breaking strength of the fiber is 142.6 MPa.However,the surface of the fiber prepared by adding protease crosslinked spinning solution after mixing SPI and CMC-Na was smooth.There are obvious stripes oriented along the axis of the fiber.The surface morp Hology of the blend fiber was the best when the crosslinking time was 20 min and 40 min.For the modified casein / sodium carboxymethyl cellulose blend fiber,the mechanical properties of the modified casein fiber increased.The fluidity of spinning solution is proportional to the content of sodium carboxymethyl cellulose and inversely proportional to p H.The infrared spectrum analysis of the fiber showed that there was a good interaction between the modified casein and carboxymethyl cellulose sodium(CMC-Na).The blend fiber with 30% CMC-Na(compared with modified casein)has better properties.The surface of the fiber is dense and has obvious stripes oriented along the axis of the fiber,The breaking strength of the fiber is 341.19 MPa.