改性纤维素纳米晶/PBAT复合材料的制备与性能

Preparation and properties of modified cellulose nanocrystal/PBAT composites

针对聚对苯二甲酸-己二酸丁二酯(PBAT)力学性能和阻隔性能不佳的问题,采用醇-水溶液法制备了硅烷偶联剂改性的纤维素纳米晶(MCNC),将其作为填料与PBAT熔融共混获得MCNC/PBAT复合材料,考察了MCNC含量对复合材料微观结构和性能的影响。结果表明,MCNC抑制了PBAT分子链运动,降低了PBAT的结晶度,MCNC的质量分数为1%时,PBAT的结晶度降低至5.8%,另一方面,MCNC又可以通过异相成核促进PBAT结晶,显著提升了PBAT的结晶温度。少量MCNC可以在PBAT基体中均匀分散,增加复合材料的热稳定性,当MCNC的含量较高时,MCNC发生团聚,复合材料的热稳定性下降。当MCNC的质量分数为0.5%和1%时,复合材料的断裂伸长率由未加MCNC的446%升高至502%和478%;继续提高MCNC的添加量,MCNC/PBAT复合材料的断裂伸长率低于纯PBAT,这主要是因为高浓度的MCNC与PBAT间形成的刚性渗透网络结构增强了材料模量,降低了材料韧性。与纯PBAT相比,当MCNC的质量分数为1%时,复合膜的O2透过量和水蒸气透过量分别下降了31.1%和37.6%。

To improve the mechanical and barrier properties of poly(butylene adipate-co-terephthalate)(PBAT),silane coupling agent modified cellulose nanocrystals(MCNC)were prepared by the alcohol-water solution method,which was used as a filler for melt blending with PBAT to obtain MCNC/PBAT composites,and the effects of MCNC content on the microstructure and properties of the composites were investigated.It is found that the addition of MCNC can inhibit the molecular chain movement of PBAT and decrease the crystallinity of PBAT,and the crystallinity of PBAT is reduced to 5.8%with the addition of 1 wt%MCNC.On the other hand,MCNC can promote the crystallization of PBAT through heterogeneous nucleation,significantly increasing the crystallization temperature of PBAT.A small amount of MCNC can be uniformly dispersed in the PBAT matrix to increase the thermal stability of the composites,agglomeration of MCNC occurs and the thermal stability of the composites decreases with high content of MCNC.The elongation at break of the composites increases from 446%to 502%and 478%with the addition of 0.5 wt%MCNC and 1 wt%MCNC respectively,but the elongation at break of the MCNC/PBAT composite is lower than that of pure PBAT with further addition of MCNC,this is mainly attributed to the fact that the rigid percolated network structure formed between MCNC with high concentration and PBAT enhances the modulus and reduces the toughness of the composite.Compared with pure PBAT,the O2 transmission and water vapor transmission of the composite film decrease by 31.1%and 37.6%respectively,when the mass fraction of MCNC is 1%.