Poly agricultural mulch films

Another way of generating biopolymers is the fermentation of starch, sugar and other commodities by various microorganisms. Typical examples are poly(hydroxyalkanoates) (especially poly(hydroxybuty-rate) (PHB)) and poly(lactic acid) (PLA). Due to the chirality of lactic acid (D- L-form), two distinct forms of poly(lactic acid) exist (poly(L-lactic acid) and poly(D-lactic acid)). PLA is used, e.g. in biomedical application (sutures, stents, drug-delivery, preparation of bioplastic), in agriculture (mulch-film), packaging, and in blends with synthetic polymers. 

Finkenstadt, V. L., and Tisserat, B. (2010] Poly(lactic acid] and osage orange wood fiber composites for agricultural mulch films, Ind. Crop. Prod, 31,316-320. 

At the time of writing, the applications of biodegradable polymers are confined mostly to the field of agriculture, where they are used in products with limited lifetimes, such as mulch films and pellets for the controlled release of herbicides. The synthetic polyesters used in medical applications, principally polylactide and poly(lactide-co-glycolide), while claimed to be biodegradable, are degraded in the body mainly, if not entirely, by chemical hydrolysis. There is little evidence that the hydrolysis of these polyesters of a-hydroxyacids can be catalyzed by hydrolase or depolymerase enzymes. 

Otey et al. [61, 68-71] also described blends of starch with synthetic polymers, in which gelatinized starch was used instead of starch granules. The initial films, composed of 90 per cent of starch blended with poly(ethylene-co-acrylic acid) (EAA), were obtained by casting from aqueous dispersions or by dry milling in a rubber mill, followed by a hot roll treatment, but only the cast films attained acceptable characteristics [71]. These materials were intended for application as mulch films for agriculture. 

Poly(e-caprolactone)/PLA Blends Poly( -caprolactone) (PCL) is a water-insoluble biodegradable, petroleum-based aliphatic polyester synthesized by ringopening polymerization of -caprolactone (e-CL) [81, 82]. PCL blends are widely used in many applications such as compostable bags for yard waste or other organics collection, disposable food service items, food packaging, health care products, mulch films in agriculture, and adhesives [81, 82, 101-103]. The nontoxicity, biocompatibility. 

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