Natural oils as coupling agents in recycled polypropylene wood flour composites: Mechanical, thermal and morphological properties

Recycled polypropylene was reinforced with treated and non-treated wood flour with different natural oils. Four natural oils were used as coupling agents, namely hexanoic (C6), octanoic (C8), decanoic (C10) and dodecanoic (C12) acids. The mechanical, thermal and morphological properties of the resulting composites were evaluated. The usage of natural oils as coupling agents clearly improved the interfacial adhesion between wood flour and the polypropylene matrix while enhancing the mechanical and thermal properties. Better results were obtained when C8 was used. The improvement in the mechanical and thermal properties of the composites imparted by C8 is similar to that promoted by maleic anhydride-grafted polypropylene. The mechanical and thermal properties of the composites were affected by the boiling temperature and chain length of the natural oil used.