纳米ZnO填充乙烯-醋酸乙烯酯共聚物的动态流变行为

为提供纳米ZnO/乙烯-醋酸乙烯酯共聚物(EVA)复合材料加工及性能优化的理论依据,通过熔融共混法制备了纳米ZnO/EVA复合材料,采用DSC研究了复合材料的熔融结晶行为,采用旋转流变仪分析了纳米ZnO质量分数以及偶联剂表面处理对复合材料体系动态流变行为的影响。结果表明:随着纳米ZnO质量分数的提高,纳米ZnO/EVA复合材料的结晶温度和熔融温度均先上升后下降;但改性纳米ZnO质量分数对改性纳米ZnO/EVA复合材料的熔融温度和结晶温度影响不大。当纳米ZnO的质量分数大于20%时,纳米ZnO/EVA体系的复数黏度发生突变,储存模量-角频率曲线在低频区出现第二平台,对应于应变扫描曲线上出现的两段线性黏弹区域,表明因纳米ZnO粒子间相互关联、团聚及粒子与基体间的相互作用形成了局部有序的逾渗网络结构;而纳米ZnO经偶联剂表面处理后,体系的复数黏度下降,储存模量-角频率曲线没有出现平台,说明改性纳米ZnO在复合材料体系中分散得更加均匀。研究表明偶联剂对纳米ZnO的表面处理改善了纳米ZnO在EVA中的分散性。

Dynamic rheological behavior of ethylene-vinyl acetate copolymer filled with nano-ZnO

In order to provide the theoretical basis for the process and performance optimization of nano-ZnO/ethylene-vinyl acetate copolymer (EVA) composites, nano-ZnO/EVA composites were prepared by melt blending method. The melting and crystallization behaviors of the composites were studied by DSC. The influence of the mass fraction and surface-modification by coupling agent of nano-ZnO on dynamic rheological behavior of the composite system was analyzed by rotational rheometer. The results show that both of the crystallization temperature and melting temperature of nano-ZnO/EVA composites increase firstly, and then decrease with the nano-ZnO mass fraction increasing, while the modified nano-ZnO mass fraction has little effect on melting temperature and crystallization temperature of modified nano-ZnO/EVA composites. The complex viscosity of nano-ZnO/EVA system changes suddenly when the mass fraction of nano-ZnO is greater than 20%, and the storage modulus-angular frequency curve shows the second plateau at low frequency region which corresponding to the two section of linear viscoelastic regions at strain scanning curves, and indicate that local ordered percolation network structure is formed due to the correlation, glomeration between nano-ZnO particles and the interaction between particles and matrix. While after the surface-modification of nano-ZnO by coupling agent, the complex viscosity of system decreases and the plateau of storage modulus-angular frequency curve does not appear, which indicates that the modified nano-ZnO particles are dispersed more homogeneously in the composite system. The research shows that surface-modification of nano-ZnO by coupling agent improves the dispersibility of nano-ZnO in EVA.