The effect of silane crosslinking on the physical properties of high density polyethylene/wood flour composites

In this study, effect of moisture content of flour on degree of crosslinking during production of silane –crosslinked wood flour polyethylene composite was investigated. Crosslinked composites were produced by adding a silane solution to the compounding extrusion process of pre-dried as well as non-dried wood flour (WF) and high density polyethylene. Their degree of crosslinking after processing and two week was determined. The gel content of the wet WF composite proved that they were crosslinked which confirm silanes had been grafted in the composite during the compounding process. The water absorption, thickness swelling and the creep response of the crosslinked composites were tested in order to establish structure–properties relations. The results showed that all crosslinked composites displayed less water absorption (WA), less thickness swelling (TS), and lower creep responses compared with non-crosslinked control samples. However, the results proved that the degree and rate of crosslinking decreases when wood flour with higher moisture content is used in the compounding process. From the fracture surface studies scattering electron microscope (SEM) it can be concluded that the crosslinked dry WF composite attained a stronger interaction between filler and matrix than wet WF. It was concluded that the silanegrafting of composite strongly affects reduction of WA and TS.