Studies On The Reinforcing, Toughening And Flame Retardant Of PE Wood-plastic Composites

Wood plastic composite (WPC) is a new type of material, which is innocuous and environmental concerned. WPC is mainly used to replace wood and protect forest resources. However, there are still three obvious defects exist in it, such as low strength, poor toughness and flammability. In this paper, reinforcing, toughening and flame retardant of WPCs were studied, and the results are shown as follows.1. Recycled high density polyethylene (HDPE) based WPCs were prepared via melt blending method, which were reinforced by short glass fiber, Naomi fibers, glass fiber powder, basic magnesium sulfate whisker, polyamide 12 (PA12) and recycled polyvinyl chloride (PVC), respectively. The results of the mechanical properties, Vicat softening point, hardness, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) measurements show that reinforcing fillers can enhance the properties to some extent, except for the Naomi fiber. Wherein PA12 has the most satisfactory reinforcing efficiency, and unnotched impact strength, Vicat softening temperature, hardness and thermal stability of WPCs are also improved.2. Recycled HDPE based WPCs were prepared via extrusion blending method, which were toughened by maleic anhydride (MAH) grafted styrene ethylene butylene styrene (SEBS-g-MAH), maleic anhydride grafted ethylene propylene terpolymer (EPDM-g-MAH), maleic anhydride grafted polyolefin elastomer (POE-g-MAH), respectively. The results of the mechanical properties, Vicat softening point, hardness, SEM and TGA measurements show that all of them can improve the tourghness of WPC, while the toughening effect of SEBS-g-MAH is the worst and POE-g-MAH is the best. Moreover, all of toughening agents can improve the tensile strength and flexural strength of WPCs to a certain extent. EPDM-g-MAH, and POE-g-MAH also can enhance the Vicat softening temperature and hardness of WPC to a certain extent, except for SEBS-g-MAH.3. Magnesium hydroxide (MH) flame retardant WPCs were prepared via melt blending method, and MH, as the main flame retardant, was synergized with silicone powder, red phosphorus, ammonium polyphosphate (APP) with high polymerization degree, zinc borate, nano-silica(SiO2) and nano-montmorillonite.The results of Limited oxygen index (LOI), UL-94 vertical flame test, cone calorimeter (CCT), and mechanical property measurements indicate that silicone powder, red phosphorus, APP with high polymerization degree, zinc borate, nano-SiO2 have synergistic effect with MH. However, only nano-SiO2 can improve the tensile and impact properties of WPC.