All-polymer composites from recycled woven polypropylene fabrics and polyethylene film

Woven polypropylene fabrics are widely used, for example, in sacks for transportation of bulk materials in agriculture and construction. There are several important end-of-life issues with these and at present the majority of these sacks are landfilled in the UK. A new process has been developed to convert these into fully recycled all-polymer composites by incorporating waste polyethylene film as the "matrix" material. The effects of lay-up arrangement, fibre orientation, extent of cleaning and drying, processing temperature, pressure, and time were all investigated. Mechanical properties of the samples were determined using a combination of flexural, tensile, and impact testing, coupled with optical and electron microscopy. The recovery of orientation of the polypropylene tapes during heating was investigated as was the bonding between the materials. It was found that there was a balance between good bonding of the materials (at higher temperatures) versus loss of stiffness because of recovery of orientation. The properties were found to be relatively insensitive to the extent of cleaning and drying that was used. It is expected that these composites will possess good outdoor weathering resistance, and a further advantage is that they will be further recyclable at the end of their lifetime.