In the U.S., I believe most plastic chairs are made out of polyethylene. That polyethylene can definitely be.... It's a low temperature. I'm sure you maybe sat in one during the summer, and it just squashed on you. It doesn't take a lot of heat to melt that down and to form it into another shape.
I'm sorry, but I don't have the company's name. This young fellow from Castlegar moved to the Canmore area in Alberta and set up a way to heat up the plastic and squash it down into sheet goods with a fibrous material in between to basically make plastic panelling or plastic sheet goods.
The plastic is with us forever. How do we reuse it and recycle it into other more long-term forms of use, rather than a plastic chair that lasts a few summers and then basically degrades to the point, just from UV exposure, that it then becomes brittle? Most of that plastic can be recycled or reutilized in different forms.