Synthetic, petroleum-based polymer films are extremely stable and are commonly used in agriculture, food packaging, fast-food restaurants, and on military and commercial ships. However, their attractive stability is counterbalanced by two problems. One is that petroleum polymers contribute to the demand for expensive imported oil. The other is their great resistance to biodegradation. When disposed they constitute a serious problem with very negative environmental impact. For example, the most frequently used polyethylene film takes 200 years to biodegrade. On the other hand, the use of agricultural biopolymers that are easily biodegradable not only would solve these problems but would also provide a potential new use for surplus farm production. Unfortunately, films from agricultural polymers are initially inferior to synthetic polymers mostly because of their difficult moldability and poorer physicochemical properties. However, specifically modified acidic carbohydrates and proteins with disulfide bondings may produce attractive alternatives.