聚乳酸/纤维素纳米晶纳米复合物的结晶性能

Crystallization Properties of Polylactide/Cellulose Nanocrystals Nanocomposite

通过溶液混合,将纤维素纳米晶(CNC)与聚乙二醇(PEG)复合得到了改性的CNC-PEG纳米粒子,然后将其与PLA熔融共混得到PLA/CNC-PEG纳米复合物。采用扫描电子显微镜(SEM)表征了纳米复合物的形貌,结果表明,PLA/CNC-PEG复合物中纳米粒子的分散效果更均匀。采用示差扫描量热仪(DSC)研究了PLA、PLA/CNC和PLA/CNC-PEG 3个样品在不同升温速率下的结晶行为。研究结果表明,当升温速率为10℃/min时,纯PLA的结晶温度为119.6℃,结晶度为18.1%;当添加1%CNC时,PLA的结晶温度降低至112.8℃,结晶度升高至28.6%。将CNC与PEG复合后,PLA可以使PLA的结晶温度继续降低至108.4℃,结晶度继续升高至30.9%。采用Kissinger公式对各样品的非等温结晶过程进行拟和发现,添加的CNC可以使PLA的结晶活化能从119.8 k J/mol降低至91.2 k J/mol,当CNC与PEG复合后,PEG的增容作用可以使改性后的CNC与PLA的相容性显著改善,PLA的结晶活化能降低至81.2 k J/mol。

The modified CNC-PEG nanoparticles were obtained by complexing cellulose nanocrystals(CNC)with polyethylene glycol(PEG)through solution mixing,and then CNC-PEG was melt-blended with PLA to obtain PLA/CNCPEG nanocomposite.The morphology of the nanocomposite was characterized by scanning electron microscopy(SEM).It was found that the dispersion of nanoparticles in PLA/CNC-PEG composite was more uniform than that of PLA/CNC.The crystallization behavior of PLA,PLA/CNC and PLA/CNC-PEG samples at different heating rates was studied by differential scanning calorimetry(DSC).It was found that at a temperature increase rate of 10℃/min,the crystallization temperature of pure PLA was 119.6℃,and the crystallinity was 18.1%.After the introduction of 1%CNC,the PLA’s crystallization temperature was reduced to 112.8℃,and the crystallinity was increased to 28.6%.By complexing CNC with PEG,the crystallization temperature of PLA was further reduced to 108.4℃,and its crystallinity was further increased to 30.9%.The non-isothermal crystallization process of the samples was simulated by Kissinger formula.It was found that CNC reduced the crystallization activation energy of PLA from 119.8 k J/mol to 91.2 k J/mol.By complexing CNC with PEG,the compatibility between the modified CNC and PLA was enhanced due to the compatibilization of PEG,as a result,the crystallization activation energy of PLA further reduced to 81.2 k J/mol.