聚环氧棕榈油/聚乳酸共混物的动态硫化制备与性能

Preparation and properties of poly(epoxidized palm oil)/poly(lactic acid)blends via dynamic vulcanization

聚乳酸(PLA)具有优异的力学性能,无毒性、可再生、可生物降解,且生物相容性好,是目前应用最广泛的生物基塑料之一。然而,PLA价格高、脆性大、韧性差等缺点严重限制了其在更多领域的应用。为克服这些缺点,采用双螺杆挤出和注塑成型技术制备生物基的聚环氧棕榈油(PEPO)/聚乳酸(PLA)共混物以增强PLA的韧性,表征了共混物的结晶行为、流变性能、力学性能、热稳定性和微观形貌,以揭示PEPO与PLA的动态硫化机制及PEPO橡胶相对PLA的增韧机制。结果表明:环氧棕榈油(EPO)与PLA熔融共混过程中,EPO在阳离子引发剂的作用下发生自聚,进而在PLA基体中形成颗粒状PEPO橡胶相;两相结构的形成使共混物受力时发生塑性形变,导致PLA的韧性显著提升;当PEPO的用量为20wt%时,共混物的断裂伸长率和拉伸韧性分别从纯PLA的10%和4.7 MJ/m^(3)提高至100%和30.4 MJ/m^(3),但其拉伸强度、拉伸模量、储存模量和玻璃化转变温度均呈现下降趋势。

Poly(lactic acid)(PLA)has the advantages of high mechanical properties,non-toxicity,renewablility,biodegradability and biocompatability.PLA has become one of the most widely used biobased plastics.However,PLA also has the disadvantages of high cost,high brittleness and low ductility,which hinders its further application in some fields.Thus,a series of bio-based poly(epoxidized palm oil)(PEPO)/PLA blends were prepared by twinscrew extrusion and injection molding techniques.The crystallization behavior,rheological properties,mechanical properties,thermal stability and micro-morphology of the blends were studied.The dynamic vulcanization mechanism of PEPO and PLA blends as well as the toughening mechanism of PEPO rubber phase in PLA were investigated.The results show that during the melt-blending of epoxidized palm oil(EPO)and PLA,EPO can self-polymerize with the help of the cationic initiator,thus forming PEPO rubber phase in PLA matrix.The formation of twophase structure endows the blends plastic deformation under stress,leading to significant toughening efficiency on PLA.With an addition of 20wt%PEPO,the elongation at break and tensile toughness of the blend increase from 10%and 4.7 MJ/m^(3)(pure PLA)to 100%and 30.4 MJ/m^(3),respectively;but the tensile strength,tensile modulus,storage modulus and glass transition temperature of the blends decrease.