Preparation Of Polyglycolide Fiber And Its Degradation Behavior In Different Environments

With the spread of white pollution,the depletion of oil resources and the frequent occurrence of extreme weather,environmental protection has attracted more and more attention,and the use of biodegradable materials has become one of the effective ways to solve these problems.Polyglycolide（PGA）is a semi-crystalline and environmentally friendly material with good biocompatibility,mechanical properties and excellent complete degradability,which make it one of the most promising biodegradable materials.It is expected to become a substitute for petroleum-based materials widely used in biomedical,packaging materials,petroleum exploitation engineering and other fields.In this paper,PGA fiber was prepared by melt spinning,and the spinnability and the effects of drawing process on the structure and properties of PGA fiber prepared by one-step process were studied.The degradation behavior of PGA fiber in different environment（natural light,soil,different water）was further studied.On this basis,the changes of structure and properties of PGA fiber microplastics during natural landfill and seawater degradation were discussed.The main conclusions are as follows:（1）The study on the effects of drawing process on the structure and properties of PGA fiber in one-step melt spinning showed that the monofilament strength,crystallinity and crystal region orientation of PGA fiber increased with the increase of draw ratio from 2.8 times to 3.5 times,but too large draw ratio caused the occurrence of broken filament.At the same time,PGA fiber had smooth surface and good thermal stability.（2）The degradation behavior of PGA fiber in natural light and natural landfill was studied by means of mass loss rate,monofilament strength,crystalline structure,surface morphology and so on.The results showed that the mass loss rate of PGA fiber was less than 1% after 30 days of degradation,and the retention rate of monofilament strength reached 88% after 30 days of natural landfill.DSC and XRD analysis showed that the crystallinity of PGA fiber increased at first and then decreased with the increase of degradation time.The surface of the fiber was still smooth in the early stage of degradation,then it gradually became rough and granular and bamboo-like defects appeared with the progress of degradation,while the diameter of the fiber increased.（3）Compared with natural light and soil degradation,PGA fiber showed greater degradation degree in different water bodies.After 30 days of degradation in sterilized seawater and seawater,the monofilament strength of PGA fiber decreased from 5.07 c N/dtex to 0.92 c N/dtex and1.09 c N/dtex,respectively.The crystallinity of PGA fiber showed a trend of first increasing,then decreasing and then increasing with the degradation process in four kinds of water.The diffraction peak of（110）crystal face became more intense while the diffraction peak of（020）crystal face appeared after 30 days of degradation,indicating that the crystal structure changed obviously.SEM observation revealed that the surface of PGA fiber in water changed gradually from the occurrence of grooves to granular surface and bamboo defects.The obvious cracks on the fiber surface could be observed in the later stage of degradation in seawater,sterilized seawater and river water,which would result in the loss of monofilament strength.Through the comprehensive analysis of the above results,it is believed that the degradation degree of PGA fiber in different water bodies is in the following order: sterilized seawater > seawater > river water > distilled water.（4）The degradation behavior of PGA fiber microplastics in natural landfill and seawater was also discussed.Compared with PGA fiber,microplastics degraded faster in natural landfill and sea water.The mass loss rate of PGA fiber microplastics reached 5.1% after 30 days of degradation in seawater,and more serious cracks appeared on the surface.The degradation reaction was further confirmed by FTIR analysis of PGA fiber microplastics in the degradation process.Compared with the initial PGA fiber microplastics,the specific surface area and O / C ratio increased in varying degrees after degradation in soil and sea water for 30 days,and a more distinct increase in seawater was obtained.In addition,the change trend of crystallinity of PGA fiber microplastics in natural landfill and seawater degradation process was similar to that of PGA fiber.