Investigation and effect of number of recycling steps on molten flow rate and crystalline percent in injection process in wood-plastic composite

Mechanical recycling of wood products is a step towards maintaining environmental resources and reducing pollution. One of the problems of repeated recycling is the change in physical and mechanical properties, including changes in the molecular structure of products. In this research, in order to analyze the redox molecular structure, a granule of plast with a weight ratio of 70% high density polyethylene is prepared by extruding method and is injected in 5 cycles. Experimental experiments were carried out at a 60-bar injection pressure and a 70-bar retaining pressure and a second pressure time of 2 seconds. Molecular flow rates and crystalline percentages were tested to investigate the molecular structure of the recovered samples. High-density polyethylene with high chain length, with recycling and chain breakage, increased molecular weight, increased viscosity, which reduced the flow rate of molten material in recycled samples. The damage caused by the continuity of the chains and the loss of power between the chains causes an increase in the molten flow rate of 2.8 gr / 10min and the conversion of the semi crystalline molecular structure to amorphous and the reduction of the percentage of crystalline by 30% Is. Increasing the recycling cycle reduces the destruction time to 9.3 minutes in recycled samples