TMY-4及TMY-4联合TPEE对PLLA的结晶和力学性能的影响

Effects of TMY-4 and TMY-4/TPEE Combination on Crystallization and Mechanic Properties of PLLA

采用熔融共混方法将有机盐类成核剂TMY-4与热塑性聚酯弹性体TPEE加入到聚乳酸(PLLA)中,利用TMY-4提高PLLA的结晶能力和TPEE提高PLLA的冲击韧性能力的特点来改善PLLA的结晶能力和韧性,从而拓宽PLLA在市场上的应用范围。通过差示量热扫描(DSC)、X射线衍射(XRD)、偏光显微镜(POM)、扫描电镜(SEM)、力学性能测试等手段进行表征。结果表明:TMY-4大大加快了PLLA的结晶,随着TMY-4含量的增加,PLLA的结晶温度也不断增加, TMY-4质量分数为5%时,PLLA的结晶温度达到最大为111.2 ℃。在TMY-4含量增加的同时,PLLA的冷结晶温度下降,当TMY-4质量分数为0.8%时,PLLA的冷结晶消失。力学测试结果表明:随着TMY-4含量的增加,PLLA的冲击韧性不断提高,当TMY-4质量分数为5%时,PLLA的冲击强度达到 4.80 kJ/m^ 2 ,比PLLA的冲击强度(3.03 kJ/m ^2)提高了58.4%。在PLLA/TMY-4二元体系中添加不同含量TPEE制备了新的三元共混物,PLLA/TMY-4/TPEE三元体系的韧性比PLLA/TMY-4 二元体系及PLLA都高;当TPEE质量分数为40%和TMY-4质量分数为5%时,PLLA/TMY-4/TPEE三元共混物的冲击强度达到13.68 kJ/m^ 2,比PLLA的冲击强度提高了3.5倍。XRD测试结果显示TMY-4和TPEE的添加对PLLA晶型没有影响。

With using melt blending method, TMY-4 and TPEE were used to improve crystallization and melting behaviors as well as mechanical properties of polylactic acid (PLLA), and thus extend its application scope of PLLA in the market. The effect of combination of TMY-4 and TPEE on the crystallization and melting behaviors, crystal structure and mechanical properties of polymer matrix were thoroughly investigated with different characterization methods including differential scanning calorimetry (DSC), polarized optical microscopy (POM), X-ray diffraction (XRD), scanning electron microscope (SEM) and mechanical test. It was found that TMY-4 could significantly accelerate the crystallization of PLLA. When 5% mass fraction TMY-4 was added into the PLLA, the crystallization temperature of PLLA could increase to 111.2 ℃;the cold crystallization temperature of PLLA disappeared when TMY-4 mass fraction was 0.8%. Mechanical test results showed that the impact toughness of PLLA can be improved if more TMY-4 was added. When TMY-4 mass fraction came to 5%, the impact strength of PLLA could be 4.80 kJ/m^ 2, which was 58.4% higher than that of PLLA (3.03 kJ/m^ 2). A new ternary blend system has been prepared by adding TPEE into different contents in PLLA/TMY-4 binary system. The toughness of PLLA/TMY-4/TPEE ternary system was higher than that of PLLA/TMY-4 binary system and PLLA. When TPEE mass fraction was 40% and TMY-4 mass fraction was 5%, the impact strength of PLLA/TMY-4/TPEE ternary blend system could reach 13.68 kJ/m ^2, which was 3.5 times higher than that of PLLA. XRD test results indicated that the addition of TMY-4 and TPEE had no impact on the crystal structure of PLLA.