Polystyrene (PS) is a common hard plastic, perhaps most well known for it's use as a foam in packaging and building insulation. In common parlance, the word Polystyrene, or the brandname Styrofoam, often refer to this foamed form, however the full name for that material is Expanded Polystyrene. Regular, or non-foamed Polystyrene is a typical, hard plastic, similar to ABS, or PET. Perhaps due to this confusion with it's foamed form, most local government kerbside recycling services specifically state that Polystyrene is not accepted, even though it has properties which make it suitable for recycling. Some confusion occurs here as PS is designated by one of the Resin Identification codes, which are often assumed to mean that a material should be placed in a recycling bin. These factors most likely result in a large amount of non-foamed Polystyrene not being effectively recycled. The melt flow index of Polystyrene is between 5 and 25.
Do not burn Polystyrene. When melting polystyrene, it emits about 5x as many harmful fumes as Polyethylene and Polypropylene. The fumes from PS are especially harmful and people working with this plastic must wear a fitted gas mask, with activated charcoal filters. When not operating machines related to PS, keep at least 2 meters away from the sources of fumes, even while wearing a mask. Limit working time with melted PS to 8 hours a week.