Starch-grafted-polypropylene/kenaf fibres composites. Part 2: thermal stability and dynamic-mechanical response

Kenaf fibres of different aspect ratios (L/D = 30 and 160) were melt compounded in an internal mixer with two types of starch-grafted-polypropylene matrices (G906PF and G906PJ) at various loadings, i.e. 10, 20 and 30 wt%. The compound was then compression-moulded into plaques of 1-mm thickness. Thermal, rheological and dynamic mechanical properties of the composite samples were investigated by several techniques involving differential scanning calorimetry, thermogravimetric analysis, melt flow index, Vicat softening point and dynamic mechanical thermal analysis. The results indicated that both thermal and mechanical properties of the composites were remarkably improved by kenaf fibres. Loss modulus and loss factor showed a shift of peak transitions to higher temperatures. Finally, the properties of the investigated composite materials were not affected by the fibre aspect ratio.