多壁碳纳米管接枝聚己内酯对聚左旋乳酸结晶行为和热稳定性的影响

Effects of multi-walled carbon nanotubes grafted polycaprolactone on crystallization behavior and thermal stability of poly(L-lactic acid)

通过羟基化多壁碳纳米管(MWCNTs-OH)引发ε-己内酯(ε-CL)开环聚合制备了聚己内酯(PCL)链接枝的MWCNTs-OH (MWCNTs-OH-g-PCL)。利用溶液共混获得具有不同MWCNTs-OH-g-PCL含量的MWCNTs-OH-g-PCL/聚左旋乳酸(PLLA)复合材料。通过FTIR测试发现,MWCNTs-OH-g-PCL在1 720cm-1附近出现PCL中的羰基(C=O)伸缩振动峰,表明接枝产物合成成功。通过DSC、偏光显微镜(POM)和TGA观察研究了MWCNTs-OH-g-PCL的加入对PLLA均聚物结晶行为和热稳定性的影响。结果表明,由于MWCNTs-OH-g-PCL的异质成核作用及PCL的增塑作用,MWCNTs-OH-g-PCL/PLLA复合材料的结晶度和最佳等温结晶温度增大。MWCNTs-OH-g-PCL中PCL的接枝量为66%,MWCNTs-OH-g-PCL/PLLA复合材料的分解温度提高了约30℃。

The hydroxylated multi-walled carbon nanotubes(MWCNTs-OH)initiated the ring-opening polymerization ofε-caprolactone (ε-CL),and polycaprolactone(PCL)grafted MWCNTs-OH(MWCNTs-OH-g-PCL)was prepared.The MWCNTs-OH-g-PCL/poly(L-lactic acid)(PLLA)composites were obtained by solution blending which had different contents of MWCNTs-OH-g-PCL.The grafted product was characterized by FTIR.It is found that MWCNTs-OH-g-PCL exhibits a carbonyl(C=O)stretching vibration peak in PCL at near1 720 cm-1,indicating that the grafted product is synthesized successfully.The effects of MWCNTs-OH-g-PCL on the crystallization behavior and thermal stability of PLLA homopolymers were investigated by DSC,polarized optical microscope(POM)and TGA.The results show that the crystallinity and the optimum temperaturerate of isothermal crystallization of the MWCNTs-OH-g-PCL/PLLA composites increase by the heterogeneous nucleation of MWCNTs-OH-g-PCL and the plasticization of PCL.The results also show that the grafting amounts of PCL in the MWCNTs-OH-g-PCL is 66%,and the decomposition temperature of the MWCNTs-OH-g-PCL/PLLA composites increases by about 30℃.