Preparation And Properties Of Polylactic Acid Fibers Containing Natural Polyphenols

Polylactic acid(PLA)is a biodegradable bio-based polyester with poor antioxidant performance.Naturally occurring polyphenols are found mostly in plants and are natural oxidants.In this paper,three plant polyphenols(aloin,curcumin and rutin)were selected as natural antioxidants to prepare functional fibers with antioxidant properties using PLA as raw material.First of all,PLA blend chips were prepared using PLA as matrix and plant polyphenolsas as natural antioxidant active component by melt mixing at 175 ℃.Include PLA/aloin(PLA/A)blend chips(aloin contents were 0.5%,1%,2%,3% and 4%),PLA/curcumin(PLA/C)blend chips(curcumin contents were 0.5%,1%,2%,3% and 4%),PLA/rutin(PLA/R)blend chips(rutin contents were 0.5%,1%,2%,3% and 4%).Then antioxidation blend fiber was prepared by melt-spinning.The effects of the proportion of polyphenols in three plants on the structure and properties of PLA were studied.Then,PLA/BVOH and PLA/BVOH/R blend chips were prepared using PLA as matrix and Butenediol Vinyl Alcohol Co-polymer(BVOH)as hydrophilic modification material component by melt mixing at 195 ℃,BVOH content was 5%,10%,20%,30%,40%,rutin content was 3%)and the blend slice was fused and spun to prepare antioxidant blend fiber.The effects of BVOH ratio on physical properties,oxidation resistance and sustained release properties of PLA fiber and PLA/R fiber were studied.The main research contents and results are as follows:(1)In the blend system of PLA and natural polyphenols,SEM images showed that the three plant polyphenols did not agglomerate and had good dispersion after blending with PLA;the three plant polyphenols had no significant effect on the crystallinity of PLA,but when a certain content was added,TC,TM and TG moved to low temperature,which played the role of small molecular plasticizer.(2)The addition of three polyphenols can significantly improve the antioxidant performance of PLA fiber.The antioxidant rate increases with the increase of polyphenol content.Compared with pure PLA fiber,the breaking strength of PLA / R,PLA / A and PLA /C fibers first increases and then decreases with the increase of polyphenol content.(3)The addition of bvoh can significantly improve the hydrophilicity of PLA.With the increase of bvoh content,the water contact angle of PLA / bvoh decreases gradually.Compared with PLA fiber,the fiber strength decreases with the increase of bvoh content.Compared with PLA / R,the fiber strength increases first and then decreases after adding bvoh.(4)The antioxidant capacity of PLA / bvoh / R with different bvoh content was analyzed by detecting the ABTS radical scavenging rate in PBS buffer.The results showed that the antioxidant capacity of PLA / R3 could be significantly improved after adding bvoh.When the bvoh content was 5%,10%,20%,30% and 40%,the antioxidant rates of fiber were 78%,87%,100%,100% and 100% respectively.(5)The content of bvoh will directly affect the release effect of Rutin in PLA / bvoh / R fiber in PBS buffer.The higher the content of bvoh,the higher the cumulative release rate of rutin.After 7 days,the cumulative release rate of PLA / R3 fiber is 10.3%,and that of pla60 /bvoh40-r3 fiber is 82.2%.