Manufacturing sisal–polypropylene composites with minimum fibre degradation

Natural fibres, such as sisal, flax and jute, possess good reinforcing capability when properly compounded with polymers. These fibres are relatively inexpensive, originate from renewable resources and possess favourable values of specific strength and specific modulus. Thermoplastic polymers have a shorter cycle time as well as reprocessability despite problems with high viscosities and poor fibre wetting. The renewability of natural fibres and the recyclability of thermoplastic polymers provide an attractive eco-friendly quality to the resulting natural fibre-reinforced thermoplastic composite materials. Common methods for manufacturing natural fibre-reinforced thermoplastic composites, injection moulding and extrusion, tend to degrade the fibres during processing. Development of a simple manufacturing technique for sisal fibre-reinforced polypropylene composites, that minimises fibre degradation and can be used in developing countries, is the main objective of this study. Composite sheets with a fibre length greater than 10 mm and a fibre mass fraction in the range 15% to 35% exhibited good mechanical properties.