Tensile and fatigue characterisation of textile cotton waste/polypropylene laminates

Short fibre based cotton flocks from end-of-life jeans fabric (denim twill weave) were introduced in an amount of 16 wt.% in a polypropylene (PP) matrix using a specifically designed manufacturing process to preserve as much as possible the properties of the cotton waste during injection moulding. This involved a first phase of binding the cotton flocks on polyvinyl acetate (PVAc) support, then pelletizing them with PP and finally extruding the final composite. The resulting composites were subjected to morphological, tensile and fatigue characterisation with stress levels from 50 to 90% of ultimate tensile strength. Results indicated that injection moulding offered a sufficient uniformity of properties to the composite, albeit with some occurrence of pull-out during loading. In particular, the tensile performance exceeded that of the pure matrix in a measure compatible with the amount of fibres introduced. In addition, tensile fatigue loading up to 5000 cycles evidenced a limited amount of degradation for maximum applied stresses up to 70% of composite tensile strength.