Thermoplastic Elastomer (TPE) Infill for Synthetic Turf

The term thermoplastic elastomer (TPE) can be applied to a wide range of chemistries. These include styrenic block copolymers, thermoplastic polyurethane elastomers, polyamide block copolymers, copolyester elastomers, thermoplastic polyolefins, and thermoplastic vulcanizates. Styrenic block copolymers appear to be the most common chemistry used in infill, though other chemistries can be used in TPE infill. TPE usually does not require a curing agent. Thermoplastic vulcanizates (TPV), however, are an exception that get classified as TPE and do utilize curing agents like sulfur. 

TPE is often advertised as being free of chemicals associated with other types of rubber infill, such as phthalates, PFOS, PAHs, VOCs, and heavy metals. While testing data are quite limited, the available data do indicate that TPE has lower concentrations of these residual chemicals than other types of rubber infill. Some residual chemicals may be present depending on the additives in the TPE. A 2017 Norewegian Environmental Agency study identified one phthalate and a number of heavy metals present at detectable levels in TPE samples provided by two suppliers, but the same study tested for a several PCBs, PAHs, or alkylphenol ehtoxylates and did not detect any of these compounds. This study also estimated that TPE is associated with the highest levels of greenhouse gas emissions among the most typical types of infill used in synthetic turf, primarily due to the fact that it is generally made from virgin materials. 

Because so many different chemistries fall under the term thermoplastic elastomer, it can be difficult to determine precisely what chemistry is used in any individual product, and some products get marketed as TPE that do not seem to fall into this category. For instance, at least one product was identified that consisted mostly of polyvinyl chloride (PVC). This Common Product describes a styrenic block copolymer thermoplastic elastomer designed to be used as infill in artificial turf. Products intended for indoor use may include a flame retardant, and some products may include biocides and organometallic catalysts, though none of these were determined to be common.