PLA/PCL共混膜的制备及性能研究

目的研究PCL含量对PLA/PCL共混包装膜性能的影响,以改善PLA的韧性。方法将不同质量比的PLA和PCL树脂均匀混合,而后熔融挤出吹膜制得PLA/PCL共混膜。对制得的共混膜进行力学性能测试,获得拉伸强度和断裂伸长率,再通过扫描电镜分析观察其微观断面,采用DSC测试分析其熔融结晶行为,通过氧气透过性能和透湿性能的测试获得其阻隔性能。结果通过扫描电镜与红外光谱发现,PLA与PCL为两相结构,界面不相容;力学性能显示当PCL的质量少于20%时,对PLA的增韧效果不明显;当PCL的质量为50%时,PLA的断裂伸长率从2.9%提高到290%;DSC结果发现,PCL的加入有助于降低PLA的玻璃化转变温度,提高结晶度;阻隔性能结果表明,随着PCL质量比的增大,共混膜的氧气透过系数和透湿系数下降,阻隔性得到提高。结论 PCL的加入能提高PLA的韧性,当PCL与PLA质量比为3∶7时,共混膜具有最佳的性能。

Preparations and Performance Research of PLA/PCL Blending Film

The work aims to research the effect of PCL content on the performances of PLA/PCL blending packaging film, so as to improve the toughness of PLA. PCL and PLA resins with various mass ratios were mixed evenly, and then PLA/PCL blending films were produced by melt extrusion method. Mechanical properties of the prepared blending films were tested to obtain tensile strength and elongation at break. Scanning electron microscope was used to analyze the fracture profile. DSC was used to test and analyze the crystallization behavior. Oxygen permeability test and water vapor transmission test were used to get the barrier property. Based on the findings of scanning electron microscope and infrared spectroscopic analysis, PLA and PCL were two-phase structures and the interface was incompatible. The mechanical properties found that, the elongation at break of PLA would not be improved dramatically when the mass of PCL was under 20%. The elongation at break of PLA was increased from 2.9% to 290% when the mass of PCL was 50%. Moreover, DSC showed that the added PCL contributed to decreasing the glass transmission temperature and increasing the degree of crystallinity. The results of barrier properties proved that, with the increase of PCL mass ratio, the oxygen permeability and water vapor transmission of the blending films were reduced and the barrier properties were improved. The added PCL is likely to improve the elongation at break of PLA. When the mass ratio of PCL to PLA is 3:7, the blending film has the optimum performance.