Biodegradable Polymers and Their Practical Utility Thermoplastic

The environmental impact of persistent plastic wastes is raising general global concern, and disposal methods are limited. Incineration may generate toxic air pollution, satisfactory landfi ll sites are limited, and recycling methods for com-mingled waste are expensive and often energy- intensive. In addition, petroleum resources are fi nite and are becoming limited. It will be important to fi nd durable plastic substitutes, especially in short- term packaging and disposable applications. The continuously growing public concern in the problem has stimulated research interest in biodegradable polymers as alternatives to conventional nondegradable polymers such as polyethylene and polystyrene etc. Several concerns must be addressed prior to commercial use of biobased primary packaging materials. These concerns include degradation rates under various conditions, changes in mechanical properties during storage, potential for micro-bial growth, and release of harmful compounds into packaged food products. Furthermore, the biopackaging must function as food packaging and meet the requirements of particular food products. In Europe, the biopackaging fi eld is regulated primarily by two EU directives: “ Plastic Materials and Articles Intended to Come into Contact with Foodstuffs ” (90/128/EEC), with later amendments, and “ Packaging and Packaging Waste Directive ” (94/62/EEC). Biopackaging often has diffi culties in complying with the migration requirements of the directive on “ Plastic Materials and Articles Intended to Come into Contact with Foodstuffs ”. Furthermore, several of the raw materials and additives used to produce biopackaging materials are not included in the list of approved components. Polymers derived from renewable resources ( “ biopoly-mers ” ) are broadly classifi ed according to the method of production. This gives the following three main categories: • Polymers directly extracted/removed from natural materials (mainly plants): Examples are polysaccharides such as starch and cellulose and proteins such as casein and wheat gluten