The invention provides novel polyesters, fibers and films, nonwovens from the fibers and disposable products of the polyesters such as diapers. The products are degradable under the conditions typically existing in waste compositing 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 polyester ingredients, such as polyethylene terephthalate, copolymerized with an alkali metal or alkaline earth metal 4-sulfophthalic acid derivative, and other ingredients, such as polyethylene ether glycols and/or non-aromatic diacids, such as adipic and glutaric acids.