GMA和共单体对聚乙烯木塑复合材料的直接反应增容

通过甲基丙烯酸缩水甘油酯(GMA)、聚乙烯(PE)、木粉和其它助剂的熔融挤出,实现了GMA及GMA与共单体对PE和木粉的直接反应增容.通过扫描电镜(SEM)观测了PE基木塑复合材料(WPC)的冲击断面形貌.测试了WPC经抽提后所得木粉的傅立叶变换红外光谱(FTIR)和WPC的力学性能及热变形温度(HDT).研究了共单体苯乙烯(St)和抑交联剂亚磷酸三苯酯(TPP)对反应增容的影响.结果显示,经GMA和引发剂反应增容后,有部分PE分子键合到了木粉粒子上,从而增强了木塑两相的结合力;St的加入有利于提高GMA的接枝率,导致更多PE分子键合到了木粉粒子上,而TPP的加入则使GMA的接枝率有所下降.经GMA和引发剂直接反应增容后,WPC的力学性能和HDT均明显改善;St的加入有助于抑制PE的交联,但并未造成WPC力学性能和HDT的明显劣化;同时加入St和TPP后,WPC的HDT有所下降,而断裂伸长率和冲击强度则明显提高.     

The effects of wood-flour on combustion and thermal degradation behaviors of PVC in wood-flour/poly(vinyl chloride) composites

The effects of wood-flour on combustion and thermal degradation behaviors of PVC in wood-flour/poly (vinyl chloride) composites (WF-PVC) were investigated by using cone calorimeter (CONE) and TGA. The results show that thermal degradation behavior of WF-PVC composites has obvious characteristics of that of PVC. Interactions occur between wood-flour and PVC during the combustion and thermal degradation of WF-PVC composites. The thermal degradation of wood-flour can be accelerated by pure PVC. Moreover, the char formation can be raised by adding wood-flour to PVC. Compared with PVC at all flaming stage, when heat flux is kept at 50 kW m⁻², the average heat release rate (av-HRR), the total heat release (THR), the total smoke production (TSP) and the average specific extinction area (av-SEA) of WF-PVC composites are respectively reduced by 44%, 9.2%, 25.8% and 29.9%. In WF-PVC composites, the wood-flour has remarkable effects on the properties of heat release and smoke release of PVC.     

Biodegradation and thermal decomposition of poly(lactic acid)-based materials reinforced by hydrophilic fillers

The effect of hydrophilic fillers (starch and wood-flour) on the degradation and decomposition of poly(lactic acid) (PLA) based materials was investigated. Biodegradation was evaluated by composting under controlled conditions in accordance with AS ISO 14855. Thermal decomposition was studied by thermogravimetry (TGA). Morphological variations during biodegradation were investigated by SEM examination. It was found that biodegradation rates of PLA/starch blends and PLA/wood-flour composites were lower than that of pure cellulose but higher than that of pure PLA. The biodegradation rate was increased from about 60% to 80% when the starch content was increased from 10% to 40% after 80 days. Both starch and wood-flour accelerated thermal decomposition of PLA, and starch exhibited a relatively stronger affect then wood-flour. The decomposition temperature of PLA was decreased about 40 °C when the filler content was increased to 40%. Small polar molecules released during thermal decomposition of starch and wood-flour were attributed to the thermal decomposition behaviours of the PLA based blends and composites and their role is further discussed in this paper.