The aliphatic polyhydroxy compound can be an aliphatic diol such as ethylene glycol, 1,2-propanediol, or 1,3-propanediol; an aliphatic polyhydric alcohol such as glycerol, glucose, or mannose; an aliphatic diol carboxylic acid such as 2,3-dihydroxypropionic acid or tartaric acid; or, most preferably, an aliphatic polyhydric carboxylic acid such as a glucaric acid.