A Mystery

We have a huge green and white wide stripe fabric scrap that we have in the past draped over the tattered couch. I took it out of storage and it smelled chemically so I washed it again and it still smells like chemicals. This never happened before I am thinking it must be some non cotton elements that are deteriorating. The fabric has elastic woven into it. I've owned this fabric for over 20 years.  It's strange but I believe this is what's happening. I do have some all-cotton fabric in a closet and I can dig that out and use it.