Tyvek is commonly known for its use in express mail envelopes, or as house wrap those large sheets you see on houses in construction.
Tyvek is a 100% microfiber plastic, comprised of millions of interlocking filaments, as thin as a 1⁄4 of the size of human hair. The random interlocking fibers are fused into a sheet which in turn make a sturdy, rip resistant material which is paper thin but incredibly strong.
Tyvek is made of H.D.P.E.
HDPE is an acronym for High Density Polyethylene. High Density Polyethylene is a polyethylene thermoplastic made from petroleum. HDPE is commonly recycled and made into composite wood or plastic lumber.
DuPont is the manufacturer of Tyvek and has a very lengthy [FAQ about Tyvek if you're interested in digging in deeper here](HDPE is an acronym for High Density Polyethylene. High Density Polyethylene is a polyethylene thermoplastic made from petroleum. HDPE is commonly recycled and made into composite wood or plastic lumber.).