Polyethylene terephthalate
Since the development of gel memory foam, other materials have been added. Aloe vera, green tea extract and activated charcoal have been combined with the foam to reduce odors and even provide aromatherapy while sleeping. Rayon has been used in woven mattress covers over memory foam beds to wick moisture away from the body to increase comfort. Phase-change materials (PCMs) have also been used in the covers that are used on memory foam pillows, beds, and mattress pads. Other materials, apart from polyurethane, have also been shown to exhibit the properties necessary to make memory foam. Polyethylene terephthalate is one such polymeric material, which provides certain benefits over polyurethane, such as recyclability, lightness, and thermal insulation.