用三氟丙基三甲氧基硅烷(TF3)、十七氟癸基三甲氧基硅烷(TF17)对木粉表面进行改性处理.将改性木粉与聚偏氟乙烯(PVDF)熔融共混制备木塑复合材料(WPC),考察氟硅烷偶联剂处理用量对紫外线辐照后WPC抗弯强度及冲击性能的影响,分析WPC经紫外线辐照后玻璃化转变温度(Tg)、储能模量(E')、损耗因子(tanδ)、熔点(T_M)和结晶度(X_c)的变化情况.结果表明,1.0wt% TF3改性木粉提高了WPC的力学性能,维持WPC经紫外线辐照后恒定的力学性能;TF17不能有效改善木粉与PVDF的界面性能及增强WPC的力学性能,但能促进经紫外线辐照后WPC内自由基之间的交联反应.TF3改性WPC经紫外线辐照后的交联反应发生在界面层和连续相,形成了有利于链段运动、支化程度高的分子链结构,Tg降低,损耗峰降低,松弛温度区间变窄.TF17改性WPC经紫外线辐照后的交联反应主要发生在连续相,在低温区间内储能模量增加,Tg提高,损耗峰降低,松弛温度区间变宽.当氟硅烷改性WPC经紫外线辐照后发生交联时,无定形区域周边的分子链重新排列,形成较为有序结晶,结晶熔融热(△H_f)增加,Xc增大.
The surface of wood flour was modified using trifluoropropyl-trimethoxysilane (TF3) and(heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane (TF17),and then it was melt-blended with poly (vinylidene fluoride)(PVDF) and extruded into wood-plastic composite(WPC).The effects of the fluorinated silane on the composite flexural strength and impact strength were investigated.Glass-transition temperature(Tg)、storage modulus(E')、loss factor(tanδ)、fusion point (T_M) and degree of crystallinity (X_c) of WPC after ultraviolet irradiation were analyzed.The results showed that wood flour treated by 1.0wt% TF3 could improve mechanical properties of WPC,furerthmore,maintaine the mechanical properties after ultraviolet irradiation;TF17 does not improve the interface between wood flour and PVDF,however,crosslink reaction in WPC after uItraviolet irradiation is accelerated by TF17.After ultraviolet irradiation,Crosslink reactions in WPC (TF3 modification)take place in the interface layer and the continuous phase. Molecular chain structure having high degree of branching are formed,Tg and loss peak decrease,relaxation temperature zone become narrow; Crosslink reactions in WPC (TF17 modification) take place in the continuous phase.E' in lower temperature zone and Tg increase,loss peak decreases,relaxation temperature zone become wide.While crosslink reactions in WPC take place,molecular chains rearrange around the amorphous and crystals were formed.which increase melting endotherms (△Hf)and Xc.
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