Application Of Recycled Polyester In Wood Plastic Composites

Recycled polyester is widely used for preparation of plasitic alloys by melt extrusion and processing fiber by melt-spinning. Polyester fiber is not proper to use in textile indutry due to poor properties. The short fibers are therefore used as filler in the composites. This work studies the effects of the content of polyethylene terephthalate(PET) fiber on the properties of resulting wood flour/HDPE composites(PF-WPC). The PET fibers were treated with alkaline orγ-methacryloxypropyl trimethoxy silane (KH570) and then characterized using the scanning electron microscope (SEM) and Fourier transform infrared spectrum (FT-IR). The effects of content of PET. distribution of PET, surface treatments of PET on the properties of the PF reinforced WPC were investigated. The optimized processing parameters were determined accordingly.Compared to unreinforced WPC, the mechanical properties and water resistance of PF-WPC were improved. The optimum PET conetent was about 3%, over which the strength and water resistance of PF-WPC decreased due to uneven dispersion and agglomeration of PET fiber. Either grafting maleic anhydride (MA) onto HDPE or surface treating PET fiber with NaOH and KH570 can improve the properties of the resulting PF-WPC. Treatment of PET fiber with NaOH caused an increase in water uptake and a reduction in the mechanical properties of the resulting PF-WPC.Recycled polyethylene terephthalate (rPET) was modified through melt compounding with MAPE in the presence of titanium tetrabutoxide (Ti(OBu)4) as transesterification catalyst. The effect of the content of Ti(OBu)4 on the properties of rPET/MAPE was investigated. To obtain molding method and processing conditions for wood/rPET composites, modified rPET melt compounded with wood flour to prepare polyester/wood flour composites in diffirent processing methods.Rheologic study indicated that the viscosity of rPET/MAPE was rapidly decreased with increase of frequency, showing a shear thinning behavior. The mechanical properties of rPET/MAPE blend was weak due to the two-phase interface between rPET and MAPE as observed by SEM. The addition of Ti(OBu)4 increased the mechanical properties and viscosity of rPET/MAPE, which attributed to the effective improvement of interfacial compatibility between rPET and MAPE. As the amount of Ti(OBu)4 exceeded 1%, the mechanical properties and viscosity of rPET/MAPE decreased, which may be due to PET degradation at high temperature. Addition of Ti(OBu)4 didn't decrease melt point of PET. The mechanical properties of polyester/wood flour composites contained modified rPET and wood flour by compression molding were poor. The single-screw extrusion wasn't appropriate for preparation of polyester/wood flour composites due to wood degradation in the extrudsion chamber.