The problem with most histories of materials is that the date it was invented, first used, and commercially available are three different dates. Rayon is the worst of any - I have forgotten the exact dates, but it was invented in something like 1850, first used in 1890, but didn't become commercially available until something like 1910, and even then it wasn't popular until 1930. Polyester was invented in 1943, I think it was, but it wasn't being first used until 1951, and it wasn't common until 1960 (don't take my dates as correct, I would have to check)