The Role of Starch in Biodegradable Thermoplastic Materials

Abstract

The increasing garbage mountain is more and more recognized as an ecological threat. Space for landfills is limited and additional incineration capacities require high capital investments and pose additional envrironmental problems. In the FRG from total annual 14 million t of household waste, 700,000 t are non-degradable plastic materials (polydefines. polystyrene and polyvinylchloride), especially for packaging. Different strategies are being followed to reduce the 5% plastics in household waste: prevention, recycling, chemical valorization, thermic utilization (incineration) and use of degradable polymers. The latter are reviewed in detail: chemical modification of classical polymers into photo-and chemo-degradable materials, physical mixing of 6-20% granular starch with polyethylene or polypropylene, coprocessing of more than 50% disintegrated starch with hydrophilic polymers like polyacrylate or polyvinylalcohol to biodegradable films for agricultural mulch or carrying bags, thermoplastic extruded starch with plasticiser containing more than 90% starch for blister packaging and disposables for fast food and finally biodegradable polyesters like poly-hydroxyhutyric acid (PHB) and polylactic acid, produced by fermentation processes. Die Funktion derStiirke in biologisch abbaubaren thermoplastischen Materialien. Der wachsende Miillberg wird mehr und mehr als okologische Bedrohung angesehen. Platz fur Deponien ist begrenzt, zusatzliche Verbrennungsanlagen erfordern hohe Investitionen und crgeben zusatzliche Umweltprobleme. In der Bundesrepublik Deutschland werden jahrlich 14 Millionen t Haushaltsabfall erzeugt, rnit einem Anteil von 700000 t nicht abbaubarer Kunststoffe (Polyolefine. Polystyrol und Polyvinylchlorid), insbesondere Verpackungsmaterialien. Verschiedene Entsorgungskonzepte werden verfolgt um den 5% -Anted an Kunststoffen im Hausmull zu verringern: Abfallvermeidung, Recycling, chemische Venvertung, thermische Verwertung (Verbrennung) und der Gebrauch abbaubarer Polymerer. Letztere werden eingehend besprochen: chemische Modifizierung klassischer Polymerer zu photolytisch-und chemisch abbaubaren Materialien, physikalisches Mischen von 6-20% granullrer Starke mit Polyethylen oder Polypropylen, Verarbeiten von mehr als 50% desintegrierter Starke mit hydrophilen Polymeren wie Polyacrylat oder Polyvinylalkohol zu biologisch abbaubaren Folien fur die Landwirtschaft oder fur Tragetaschen, thermoplastisch extrudierte Starke mit mehr als 90% Starkc fur Klarsichtverpackungen und Wegwerfartikel im Fast Food-Bereich und schlieRlich biologisch abbaubare Polyester wie Polyhydroxybuttersaure (PHB) und Polymilchsaure, die fermentativ hergestellt werden. starcwstarke 42 (1990) Nr 4. S 123-130 0 VCH Verlagsgcsellschaft mbH, D-6940 Weinhelm, 1990 0038-905619010404-0123~02 5010

Blendas compatíveis de amido termoplástico e polietileno de baixa densidade compatibilizadas com ácido cítrico

“…O amido é um dos materiais mais promissores para essa finalidade, pois é produzido em grandes quantidades em praticamente todas as regiões do mundo, tem baixo custo e pode ser utilizado tanto na produção de insumos químicos básicos como diretamente na composição de polímeros termoplásticos [1][2][3][4][5][6] . O Brasil ocupa papel de destaque na produção de amido sendo o segundo produtor mundial de mandioca, ficando atrás apenas da Nigéria e terceiro produtor mundial de milho, ficando atrás dos Estados Unidos da América e da China [7] .…”

Cellulose microfibrils from potato tuber cells: Processing and characterization of starch-cellulose microfibril composites

“…In this way, there has been considerable attention during the past two decades to the utilization of gelatinized starch for single-use biodegradable plastic items such as trash bags, shopping bags, diner utensils, planting pots, and diapers. [1][2][3][4][5][6][7] The potential advantages of such materials are their established biodegradability and that they may be disposed of by microbial action in compost piles or at sea rather than accumulating in landfills and waterways. 8 -10 In addition to these environmental advantages, starch, or any product from agricultural sources, is of interest because of its low cost and its availability as a renewable resource.…”

“…where M and L are the weight and the length, respectively, of the sample, and is the density of the material ( ϭ 1.5 g/cm 3 ). The corrected tensile modulus (E corr ) was then determined from the initial slope of the curve corr ϭ F/S corr ϭ f().…”

Low density polyethylene/starch blend films for food packaging applications

“…LDPE/starch blend is one type of degradable plastics. 11 Starch blended PE films have been reported by many workers, 12−14 but there is lack of literature on their application in food packaging. This article describes the effect of starch content (2.5-50%) in LDPE on the physicomechanical properties, barrier properties, optical properties, thermal properties, migration behaviour, and morphological behaviour of LDPE/starch blends.…”