Incorporation of poultry eggshell and litter ash as high loading polymer fillers in polypropylene

With oil supplies needed for plastic polymer generation reducing, alterative feedstock materials are required for polymer producers. Replacement of plastic feedstock with other materials, such as fillers or functional additives, is a suitable method. Many of these materials are being derived from waste sources, including potential those derived from poultry production. Eggshell and poultry litter (incinerated into ash – PL(Ash)) have been investigated to determine the effect of using as a high loading filler with polypropylene. Characterisation of both materials showed each contained minerals suitable for polymer usage, with eggshell consisting of large amounts of calcium carbonate (common polymer filler). Both were added to polypropylene in loading up to 55% wt., and were successfully compounded into consistent polymer pellets, followed by injection moulding into test samples. Despite the use of a relatively large particle size, improvement in Young’s modulus, flexural properties and impact strength were recorded. Samples however became more brittle with reductions in tensile strength and elongation. Characterisation showed both eggshell and PL(Ash) adhered with polypropylene, exhibiting full contact between particles and matrix, verifying potential as a polymer filler material and as a replacement to high amounts of oil-based polymer feedstock.