Study On Elasticity And Biodegradation Of Poly (Butylene Succinate-co-Butylene Terephthalate) (PBST) Fibers Subjected To Thermal Treatment

For the past few years, with the proliferation of synthetic fibers, the following problems they brought have become more and more serious, like pollution and limitation of oil resources. Poly(butylene succinate-co-butylene terephthalate) (PBST) fiber is a totally new kind of environment friendly copolyester, with the combination of biodegradability and superior thermal and mechanical properties, PBST copolyester with 70 mol% butylene terephthalate (BT) takes on promising potential in industrial application. On the basis of the studies so far available, this study was expected to give information on the stret alh elastic recovery mechanism of PBST fibers from the aspects of chemical structure combined with crystal structure transition, with the variation of PBST fibers' aggregation and elasticity after heat-setting. Based on the pretreatment of PBST fibers, factors which influence the process of biodegradation were discussed in this study.Tensile tests, WAXD measurements and SAXS measurements were used to investigate the elasticity and crystal structure transition of PBST fibers, then comes to a conclusion:PBST fibers possessed high elongation at break and low initial modulus and displayed good elastic recovery. Besides, the crystal structure transition only existed in PBST fibers at different deformations. The a form was dominated in PBST fibers with the deformation less than 30%, and theβform became more and more distinct and was dominated when the tensile deformation was above 35%.PBST fibers were heat-set under different thermal conditions, and the experimental result concluded that with the increment of drawing ratio, the breaking strength of PBST fibers increased while elastic recoverability tended to be diminished, which agreed with the variation trend of crystallinity and orientation. Heat-setting temperature had the similar effect to drawing ratio on the tensile properties of PBST fibers, both having a contribution to the increase of breaking strength and decrease of the elastic recovery, which agreed with the changes of aggregation. The change of tensile properties of PBST fibers at different heat-setting time showed no regular variation trend.The hydrolysis situation showed differently in solutions with various pH, and the rate could be described as Ph=4.5>pH=9.5>pH=7.0; Both crystallinity and breaking strength of PBST fibers during the hydrolysis process increased firstly and then decreased, and variation was pH=7.0> pH=9.5>pH=7.0; Variation of PBST fibers' elongation did not show any discipline in different solutions. Degradation of PBST fibers behaved much more obviously in a higher degree, as well as the crystallinity and strength.All the changes of PBST fibers' structure and property in solution with or without the bio-enzyme PS(?)were just the same, while the only different was the effect of degradation behaved much more obviously when the bio-enzyme existed.