Preparation And Characterization Of PBS/Silk Sericin Blend Fibers

(Poly(butylene succinate),PBS)is a biodegradable thermoplastic aliphatic polyester,which can be processed into a variety of products such as fibers and films.The melting point of PBS is 115 ℃,much lower than the decomposition temperature of cellulose,protein and other biomass polymers.Therefore,PBS/biomass polymers composite materials can be prepared by thermoforming methods.However,the compatibility of PBS with biomass polymers is poor,and the dispersion uniformity of PBS and biomass polymers needs to be improved by means of compatibility agent.Silk sericin is a globular protein wrapped in the outer layer of silk fibroin,which is a biomass polymer resource to be exploited.In this paper,PBS/silk sericin blend fibers were prepared by melt spinning method and silane coupling agent was used to improve the dispersion uniformity of silk sericin in PBS.The effects of PBS/silk sericin blend ratio,silane coupling agent content and post-drawing process on the properties of crystalline structure,morphological structure and mechanical strength of the fibers were investigated in the hope of obtaining PBS/silk sericin blend fibers with uniform dispersion of silk sericin.The main research work of this thesis consists of three parts:(1)The effect of the PBS/silk sericin ratio on the structure and properties of the blend fibers was investigated.The results showed that: the blend fibers has the morphological structure of silk sericin as the dispersed phase and PBS as the continuous phase;the presence of silk sericin solves the problem of high elongation at the break of PBS fiber,and the elongation at the break of the blend fibers is 8.74% when silk sericin mass fraction reaches 15%;the saturation moisture return of the blend fibers is 3.83%,which is close to the saturation moisture return of nylon in synthetic fiber,indicating that the blend fibers has excellent skin-friendly properties.In addition,the mass loss rate of the blend fibers could reach 54% after 6 weeks of the soil burial degradation test,while the mass loss rate of PBS fibers was only 1%,indicating that the blend fibers can degrade rapidly after being discarded.(2)To improve the dispersion uniformity of the silk sericin and the compatibility between PBS and silk sericin,the silane coupling agentγ-methacryloxypropyltrimethoxysilane(KH-570)was selected to modify it,and the PBS/silk sericin/KH-570 blend fibers was prepared.The results showed that the phase domain size of the silk sericin decreased and the dispersion uniformity of the silk sericin improved after the addition of KH-570.The crystallinity of the blend fibers without KH-570 was 51%,the breaking strength was 88.55 MPa and the mass loss rate was 27%after 8 weeks of soil burial degradation test;the crystallinity of the blend fibers with a2% mass fraction of KH-570 was 56%,the breaking strength was 178.80 MPa and the mass loss rate was 4% after 8 weeks of the soil burial degradation test.That indicated that KH-570 can improve the compatibility between PBS and silk sericin,increase the crystallinity and mechanical strength of the blend fibers,and the biodegradability of the fiber reduced by the altered surface structure of silk sericin.(3)The PBS/silk sericin/KH-570 blend fibers were treated with post-drawing,and the effects of drawing ratio and drawing temperature on the structure and properties of the fibers were investigated.The results showed that with the drawing ratio increases,the surface of the fibers showed obvious streaks along the stretching direction,indicating the relative displacement of PBS and silk sericin,which formed structural defects;with the drawing temperature increases,the streaks on the surface of the fibers decrease,indicating that increasing the temperature increases the movement of the molecular chains,avoiding the relative displacement of the PBS from the silk sericin,and the fibers form a dense structure.The mechanical properties and crystallinity of the blend fibers increase first and then decrease with the increase of the drawing ratio and drawing temperature.When the drawing ratio is 4 times and the drawing temperature is75 ℃,the crystallinity of the fibers can reach 61%.Under this condition,the fiber breaking strength is 2.0 c N/dtex,which is close to the mechanical strength of viscose fibers and meets the requirements of various textile processing methods such as spinning and non-wovens.