No abstract

Formulations containing high levels of gelatinized starch and various levels of polyethylene-co-acrylic acid) and, optionally, polyethylene can be readily blown into biodegradable films having the feel and general appearance of conventional palstic films. Ammonia and 2-10% moisture were essential Ingredients for obtaining uniform films. Inclusion of polyethylene in the film formulation improved the economics and increased UV stability and rate of biodegradability of the blown films. The films have potential application as agricultural mulch and packaging, especially where biodegradation is important.

No abstract

Recent patents in the starch‐based plastics area have claimed melted or “destructurized” starch as a new type of material. The term “destructurized starch” has apparently been coined after the physically modified state of starch obtained by the disruption of the granular state, resulting in the loss of order and crystallinity. A brief literature review is presented which shows that, in the 1970's. starch containing low (10–30%) water contents was extruded at elevated temperatures to give a thermoplastic melt exhibiting no residual starch crystallinity. Differential scanning calorimetry studies of starch‐g‐polymethyl acrylate and blends of starch with poly (ethylene‐co‐acrylic acid) are also presented. These data indicate that these materials, prepared in the 1970's, also contain starch which was partially or completely destructurized. Thus, although ideas and uses for destructurized starch in plastic items have proliferated in recent years, completely melted or “destructurized” starch had been conceived and used much earlier.