摘要
目前,溶液浇铸法制备纳米纤维素/聚乳酸复合材料,常将纳米纤维素直接加入聚乳酸,导致制备的复合材料各项机械性能普遍降低。为了改善其机械性能,笔者采用聚乙二醇2000作为塑化剂处理纳米纤维素,制备聚乳酸/纳米纤维素/聚乙二醇三相复合材料。通过对复合材料的微观形貌观测,力学性能分析和热稳定性分析来确定聚乙二醇的影响机制。试验结果表明,添加2%~4%聚乙二醇2000的三相复合材料的拉伸强度、撕裂强度与断裂伸长率得到了提高,材料的热稳定性相对纯聚乳酸发生了下降。而随着聚乙二醇含量逐渐增加至8%,材料的拉伸强度、撕裂强度与断裂伸长率都出现了降低,而其热稳定性回升,复合材料的玻璃化转化温度(TG)大约提升了5~6℃。同时,研究发现保持一定的聚乙二醇/纳米纤维素添加比例可获得分散均匀、性能优良的复合材料,团聚现象明显减少。综上,经过一定量的聚乙二醇2000表面改性可促进纳米纤维素在聚乳酸中的均匀分散,从而增强复合材料的综合机械性能。
The cellulose nanofiber(CNF)is a nonpolluting natural material,which is always used for enhancing the properties of composite materials.PLA(Polylactic acid)is a polymer material,which can be a basic material for preparing plate,film and 3d printing products.Aiming at preparing a composite material with excellent properties,the CNF/PLA composites were prepared through the solution casting method with PLA as the matrix and CNF as the enhanced component.Comparing to neat PLA,the composite prepared by mixing CNF and PLA directly had some drawbacks,such as low strength and high brittleness.Through the micro-morphology observation,the agglomeration and the bad dispersion condition of CNF were the mainly incentive of this phenomenon.In order to reduce the agglomeration of CNF and enhance the mechanical properties of CNF/PLA composite,the polyethylene glycol(PEG)2000 was used as a plasticizer to modify CNF and the composite with three components,i.e.,CNF,PEG2000,and PLA,were prepared by adding PEG2000 into CNF suspension,then mixing the modified CNF system with the PLA system both with the DCM as the solvent.The micro-morphology,mechanical properties,thermal stability were examined to figure out the modification mechanism of PEG acting on the CNF and PLA.The tensile strength and elongation at break were enhanced due to the improved dispersion condition of CNF and the plasticity was improved with the addition of 2%-4%PEG2000.A uniform and firm surface morphology between PLA and CNF were discovered through the SEM examination.The thermal stability was decreased due to the plasticity effect of PEG2000 acting on PLA.During the experiment,it was found that,with the content of PEG increasing to 6%-8%,the mechanical properties became worse compared to neat PLA and this phenomenon has not been reported in the previous research.Some obvious cracks between PLA and CNF were observed through micro morphology images and the thermal stability had a certain enhancement.Meanwhile,the tear resistance properties illustrated a similar trend with the tensile properties of the composites.At the same time,the relationship between the PEG and the increasing content of CNF and its agglomeration phenomenon was tested.It was found that a certain ratio of PEG/CNF could achieve a composite material with better performance,and the agglomeration phenomenon was significantly reduced.Through those analyses of the results,it was demonstrated that a certain amount of PEG would promote the dispersion of CNF and accelerate the molecular movement of PLA,which led to the enhancement of mechanical properties.The over-acceleration of molecular movement and the expanded PLA molecular gap caused by the excess PEG would do harm to the combing condition of CNF and PLA,as well as the mechanical properties of PLA itself.In conclusion,only by controlling the amount of PEG,the CNF/PLA composite with perfect properties could be achieved.In this research,both the enhancement and the weakened effect of PEG on the PLA/CNF composites were discussed.
作者
白舒扬
韩晨阳
倪忠进
倪益华
吕艳
叶晓平
BAI Shuyang;HAN Chenyang;NI Zhongjin;NI Yihua;LYU Yan;YE Xiaoping(Zhejiang Agriculture&Forestry university,School of Engineering,Hangzhou 311300,China;Zhejiang key Laboratory of Digital and Intelligent Manufacturing of Civilization and Creation Products,Lishui 323000,Zhejiang,China)
出处
《林业工程学报》
CSCD
北大核心
2020年第2期62-68,共7页
Journal of Forestry Engineering
基金
浙江省公益技术应用研究计划项目(LGG18E060002)
浙江省竹资源与高效利用协同创新中心开放项目(2017ZZY2-15)
浙江省特色文创产品数字化设计与智能制造重点实验室开放项目(ZD201804)
