The invention provides novel polyesters, fibers and films, nonwovens from the fibers and disposable products of the polyesters such as diapers from the nonwovens. The products are degradable under the conditions typically existing in waste composting processes, have low ingredient costs and yet provide strength and toughness properties adequate for end uses such as in disposable diapers. The polyesters are based upon polyethylene terephthalate copolymerized with diethylene glycol and a 5-sulfoisophthalic acid.