双向拉伸聚乳酸薄膜降解性能研究

Degradation Properties of Biaxially Stretched Polylactic Acid Films

通过双螺杆挤出机和静态拉伸机制备双向拉伸聚乳酸(BOPLA)薄膜,并将其埋于室外土层,采用分析天平、傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)、X-射线衍射仪(XRD)和差示扫描量热仪(DSC)研究了BOPLA薄膜的自然降解过程和机理。结果表明:BOPLA薄膜在降解初期因表面致密而降解缓慢,在降解10个月后表面致密层被严重侵蚀且降解深入薄膜内部,降解加速。在降解过程中结晶度、晶粒尺寸、玻璃化转变温度等性能受无定型区和结晶区降解变化的影响,在降解3个月后达到最高,之后呈现波动下降的变化趋势。

Biaxially oriented polylactic acid(BOPLA)films were prepared by twin-screw extruder and static stretching machine,and they were buried in outdoor soil.The natural degradation process and mechanism of the BOPLA films were studied by analytical balance,Fourier transform infrared spectoscopy(FI-IR),scanning electron microscope(SEM),X-ray diffraction(XRD),and differential scanning calorimetry(DSC).The results show that the BOPLA film degrades slowly due to its dense surface at the initial degradation stage.After degrading for 10 months,the dense layer on the surface is eroded seriously,and the degradation goes deep into the film,the degradation is accelerated.The crystallinity,grain size,glass transition temperature,and other properties,which affected by the degradation of crystalline and amorphous regions,reach the peak value after degrading for 3 months,and then show a fluctuating downward trend.