Modification Of Biodegradable PBAT By TPS Blending And Tis Spinning Process

PBAT(polyadipic acid/butylene terephthalate)is a kind of biodegradable semi-crystalline polyester,and its fiber development and application has attracted great attention.PBAT is a representative aliphatic aromatic copolyester,which is a biodegradable copolyester with excellent ductility,elongation at break,good heat resistance and impact resistance.Melt spinning is considered to be the most environmentally friendly fiber processing technology.However,due to the low crystallization temperature and slow crystallization rate of PBAT,the fibers tend to stick to each other during the winding process,resulting in the inability of the spun fibers to be processed after spinning.Therefore,there are few research achievements on melt spinning PBAT fibers at present.It is a scheme to improve the spinnability of PBAT by introducing nucleating agent to regulate the crystallization rate and increase the crystallization temperature in the process of melt spinning.In this paper,thermoplastic starch(TPS),a biodegradable polymer material with good degradability,was selected for blending modification of PBAT,and the spinnability of the blend and the structure and properties of the blend fiber were studied.Firstly,PBAT modified by TPS with different contents were prepared by twin-screw blending and extrusion.The structure of PBAT modified by TPS blending was characterized by FTIR,GPC and SEM.The performance of PBAT modified by TPS blending was characterized by DSC,TGA and electronic universal material testing machine.The polyhydroxyl structure of TPS will form hydrogen bonds with the carbonyl group in PBAT,resulting in a micro-crosslinking structure,which increases the interchain force,inhibits the thermal degradation of PBAT in the process of hightemperature processing,increases the molecular weight of the blends,Narrows the molecular weight distribution,and improves the thermal stability of PBAT.In addition,TPS can be used as nucleating agent to improve the crystallization temperature and crystallization rate of PBAT.The blend containing 1wt%TPS exhibits the highest crystallization temperature and the best mechanical properties,but at this ratio,the cross-linking degree between the two is the highest and the crystallization rate is the lowest.Higher TPS addition will lead to the deterioration of the mechanical properties of PBAT and TPS two-phase separation.Secondly,the spinnability of the blends was evaluated,and it was found that the polyhydroxyl structure of TPS can produce hydrogen bond crosslinking with the carbonyl group of PBAT,which improves the spinnability of PBAT.When the amount of TPS blend is 0.5wt%,1wt%,2wt% and5wt%,the modified PBAT has good spinnability.In the process of melt spinning,melt is extruded from spinners.After fiber forming,TPS plays the role of physical connection point in PABT,so that the fiber has the characteristics of high strength and high elongation.The introduction of TPS with effective content of 1wt% enables PBAT fiber to obtain the best mechanical properties,elastic properties and highest crystallinity.The fiber strength can reach 2.2c N/dtex,and the elongation at break is maintained at 96.8%.At a fixed elongation of 30%,the elastic recovery rate is 97.67%,and the F-1 fiber with 2.4 times of drawing has a crystal degree of 36.38%.The higher addition of TPS will lead to partial aggregation points in the fiber due to the microphase separation of PBAT and TPS,and the stress concentration will reduce the mechanical properties and elasticity of brittle fracture of the fiber.Finally,the degradation behavior of the spun fibers was studied in the environment without enzyme,lipase and amylase.Through observation of degradation process,degradation weight loss rate,characterization of FTIR,SEM and GPC,it was found that lipase environment was more conducive to the degradation of blend fibers.Because the ester bond in the existence of molecular structure is more likely to be attacked by lipase and hydrolyzed,resulting in the break of molecular chain and the formation of substances with lower molecular weight,thus widening the molecular weight distribution.Moreover,the hydrophilicity of TPS can act as the area of water molecule invasion in the blend fiber,accelerating the degradation of fiber.In the third week,the amorphous region that is easy to degrade has been destroyed,and the weight loss rate reaches the maximum.The study of TPS blending modified PBAT provides guidance for the spinnability of PBAT and the application of fiber.