A Review on the Applicability of Life Cycle Assessment to Evaluate the Technical and Environmental Properties of Waste Electrical and Electronic Equipment

Acrylonitrile–butadiene–styrene (ABS) copolymer and high-impact polystyrene (HIPS) are the plastics most commonly found in waste electrical and electronic equipment (WEEE), although properties generally decline with recycling. Technical studies are important in assessing the properties of recycled plastics and obtaining better evidence of their return or not to the same production cycle, through a study of their impacts and life cycle assessment (LCA). This article aimed at a literature search for information that demonstrates the importance of considering the technical property results of LCA studies on WEEE plastics. LCA studies show that recycling WEEE plastics, when compared with virgin raw material, prevents 87% of ABS gas emissions, in addition to reducing energy consumption by up to 90% for ABS and HIPS. However, some technical properties of recycled WEEE polymer material, such as impact strength and ultimate elongation, decline when compared to virgin materials, which may hinder their reinsertion into the same production cycle. These properties can be enhanced by preparing compatible mixtures of ABS and HIPS, or by mixing them with virgin polymers. Recycled ABS (not mixed with another material) can return to the same production cycle when the goal is to preserve the modulus of elasticity. Studies that investigate properties using LCA are scarce. However, they are important in determining the viability of the material returning or not to the same production cycle, which would impact the process and produce different LCA results. Recycled ABS and HIPS polymers from WEEE can return to the same function even if some properties decline, since properties can be improved when the polymers are properly mixed or made compatible, thereby lowering costs and primarily minimizing the negative environmental impacts.