A group of us are sewing face masks to prevent the spread of sputum. I've learned that the lining of an N95 mask is made of polypropylene. Polypropylene is also a common interfacing product for sewing. I want to identify polypropylene in non woven breathable "fabric" products that I have on hand around the house, for example: some "plastic" grocery bags are breathable and, I suspect, made of polypropylene.
Is there a simple test? The burn test?