Waste makes an improved plastic pallet
Appropriately named, glass reinforced plastic (GRP) is a composite thermoset material made of a plastic strengthened by fine fibres of glass. As with many other composite materials, the two components act together, each overcoming the deficits of the other. Whereas plastic resins are strong in compressive loading and relatively weak in tensile strength, the glass fibres have complementary properties. They have a strong resistance to tensile forces but have no strength against compression. The result is improved mechanical resistance for a high performance pallet with increased load and humidity resistance. Unfortunately, the use of virgin glass fibre is economically prohibitive. Although ideal, it is a very expensive material and the value of the product does not warrant its incorporation. The PLASTIC-RECYCPALLET project set about solving this problem by developing a material with a thermoplastic matrix incorporating GRP waste as a reinforcing filler. Project partners performed a detailed analysis of the injection moulding production process and pallet use. In this way they were able to define the properties the material must possess in terms of mechanical, rheological and weather resistance. Furthermore, the maximum acceptable particle size was defined to fulfill two opposing restraints. The glass must be fine enough for its filler role in the injection process but still be long enough to maintain its reinforcing properties. Finally, a grinding system was developed to produce the optimum particle size. To improve the strength and behaviour of the GRP under impact conditions, two further factors were tackled. First, the compatibility within the fibre matrix was increased. Then, the design of the pallet was modified at fragile points like the corners that are particularly vulnerable to damage. The pallet developed has uses in multiple sectors including transport of goods, the chemical industry and situations where hygiene is of prime importance.
