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Starch is a renewable and cheap natural polysaccharide from that is easily to make biodegradable plastic products. However, its products have low mechanical properties and tend to change its properties in the presence of water. For reduce the problems caused for water in the plastic product derived from starch, originate from de high hydrophilicity of this polymer, are diverse strategies such as the chemical modification of starch, the blend of starch with minor hydrophilic polymers and the superficial modification of the final products. In the present review is presented some examples of investigations related with the mentioned strategies, focused the attention in superficial modification that allow decrease the hydrophilicity of plastic products based on starch without affect the internal characterizes of material significantly. [ABSTRACT FROM AUTHOR]

In this work it was studied the optical properties and water vapor permeability (WVP) in biodegradable films made from two thermoplastic cassava starch varieties native and hydrolyzed, polylactic acid and polycaprolactone. The films were obtained by extrusion process, and their properties were rated for 1, 8, 60 and 120 days. The PVA for 120 days was between 2, 18 x 10-11 and 9, 12 x 10-11 g / Pa * s * m. Almost all the films retained their color issues with values of between 83,92 and 87,89 L, the parameter a * and b * were close to 0, resulting films with a slight tendency to yellow. The gloss values varied between 16,06 and 21,98 GU during the aging. This study found that aging affected significantly the optical properties and the WVP. [ABSTRACT FROM AUTHOR]