PEG与TMB-5对PLLA结晶及性能的协同影响

Effects of PEG and TMB-5 on the Crystallization and Properties of PLLA

聚乳酸(PLLA)结晶速率慢、韧性差,通过联合添加成核剂(TMB-5)克服PLLA难以成核,添加链段运动调节剂聚乙二醇(PEG)提高PLLA链段运动能力以实现PLLA结晶与性能的调控。采用差示扫描量热仪(DSC)、X射线衍射仪(XRD)、小角X射线衍射仪(SAXD)、偏光显微镜(POM)和力学性能测试,考察了不同配比的TMB-5和PEG对PLLA的结晶行为与韧性的影响。结果表明,在PLLA中添加TMB-5和PEG,PLLA的玻璃化转变温度下降,结晶峰温度向高温方向移动,结晶速率加快,球晶尺寸变大,同时伴随有环带球晶的出现,但对PLLA的结构和晶型没有影响。力学测试表明,TMB-5/PEG协同改善了PLLA的韧性,当添加质量分数0.5%的TMB-5和质量分数3%的PEG时,PLLA/TMB-5/PEG三元共混物的韧性达到5.05kJ/m2,比PLLA/TMB-5二元共混物、PLLA分别提高了22.9%和150%。

In order to overcome problems of slow crystallization rate and poor toughness of poly(L-lactic acid)(PLLA),the nucleating agent(TMB-5)and the chain segment motion agent polyethylene glycol(PEG)were simultaneously added to PLLA to overcome the difficulty of nucleation and improve the chain segment motion ability of PLLA.Their effects on the crystallization behaviors and toughness of PLLA were systematically investigated by differential scanning calorimetry(DSC),X-ray diffraction(XRD),small angle X-ray diffraction(SAXD),polarized optical microscopy(POM)and mechanical properties test.The results showed that the addition of TMB-5 and PEG led to the glass transition temperature decrease.The crystallization temperature of PLLA/TMB-5/PEG blends shift to the high temperature,and the nucleation rate and the crystallization rate also increase.Moreover,the banded texture could be observed with increasing of PEG content.But the structure and crystal form of PLLA was not affected.Mechanical tests showed that TMB-5 and PEG could improve the toughness of PLLA.The highest impact strength occurred when adding the mass fraction of the TMB-5/PEG was 0.5%and 3%.The value of the highest impact strength was 5.05 kJ/m 2 and increased by 22.9%and 150%than PLLA/TMB-5 blends and PLLA,respectively.