Citric acid, cross-linked polyesters

Another type of cross-linked polyesters can be prepared by using a trifunctional alcohol or trifunctional acid (or both) to give a polymer network. For example, glycerol has been used to form cross-linked polyesters with citric acid and aspartic acid [198,199]. Polymer degradation was found to coincide with total release of a low MW drug (methyldopa). 

Corrosion. Aqueous solutions of citric acid are mildly corrosive toward carbon steels. At elevated temperatures, 304 stainless steel is corroded by citric acid, but 316 stainless steel is resistant to corrosion. Many aluminum, copper, and nickel alloys are mildly corroded by citric acid. In general, glass and plastics such as fiber glass reinforced polyester, polyethylene, polypropylene, poly(vinyl chloride), and cross-linked poly(vinyl chloride) are not corroded by citric acid. 

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