Interfacial Behaviour of Wood Plastic Composite: Effect of Chemical Treatment on Wood Fibres

Interfacial strength between polymeric matrix and lignocellulosic reinforcement hasdirect effects on the properties of wood plastic composites (WPCs). There are twoapproaches to improve the interfacial adhesion between two phases in WPC:modification of the polymeric matrix or modification of the lignocellulosic fibres. Thiswork focuses on the chemical modifications of natural fibres such as lignocellulosic,enhanced by silane, alkali, benzoyl chloride and acid acrylic. The chemically treatedfibres were then compounded with polypropylene at 190°C and 40 wt%, in an internalmixer equipped with cam rotor, for all samples. Changes in the chemical structure ofchemically treated fibres were tracked by Fourier transform infra red (FTIR)spectroscopy. The intensity of O-H bond at 3400 cm-1 and formation of ester bond at1740 cm-1 were indications of changes in the chemical structure of the fibres. Theinterfacial adhesion was evaluated using adhesion factor which was obtained fromdynamic mechanical thermal analysis data. The results showed that the minimumadhesion factor is related to silane treatment which provides the best interactionbetween polymer and fibres. The tan δ peak was shifted to higher temperature for filledsamples in comparison to neat polypropylene and the amount of shift was related to themethod of chemical treatment. Different morphologies were observed in samples dueto different chemical modifications of fibres and among them, silane treatment methodof the fibres provides the best wetting action by polymeric matrix. Tensile properties andimpact resistance of the samples were determined to evaluate the effect of interfacialadhesion on the performance of the composites.