聚左旋乳酸/聚氧化乙烯共混物的拉伸行为及结构转变

Crystallization and Tensile Behavior of Poly(L-lactide)/Poly(ethylene oxide) Blend

采用熔融共混方法制备了聚左旋乳酸(PLLA)和超高分子量聚氧化乙烯(PEO)共混物,通过差示扫描量热(DSC)、扫描电子显微镜(SEM)和二维广角X射线散射(2D-WAXS)等方法系统研究了PEO的加入对不同温度下PLLA拉伸行为及拉伸过程中微观结构变化的影响.结果表明,PLLA/PEO共混物为非均相体系,PEO粒子均匀分布在PLLA中形成两相结构.PEO的加入能够显著降低PLLA的玻璃化转变温度(Tg),在25～60℃范围内显著提高PLLA的拉伸性能.在60℃拉伸时,PEO的加入提高了PLLA在拉伸过程中的结晶和形变能力.在80℃拉伸时,共混物的拉伸断裂伸长率下降,但共混物的结晶速度仍高于纯PLLA样品.

Poly（L-lactic acid）（PLLA） and PLLA/ultra high molecular weight poly （ethylene oxide）（PEO） blend were prepared by melt-mixing, respectively. The morphology and the stretching behavior as well as their dependence on stretching temperatures of PLLA and PLLA/PEO blend were studied with a combination of differential scanning calorimetry（ DSC）, scanning electron microscopy（ SEM）, and in-situ synchrotron wide-an- gle X-ray scattering（WAXS）. The PLLA/PEO blend exhibited phase-separated morphology, with PEO particles as dispersed phase evenly distributed in PLLA matrix. The addition of PEO remarkably decreases the glass transition temperature（Tg） and increases the crystallization rate of PLLA. The fracture strain of PLLA/PEO blend increases drastically under uniaxial stretching at different temperatures of 25----60 ℃. At lower stretching temperature （60 ℃ ）, the crystallization rate and fracture strain of PLLA/PEO blend increase. At higher stretching temperature （80%）, the fracture stain of the blend is lower＇than that of the pure PLLA, while the crystallization rate is still higher than that of PLLA.