Abstract: A polyester-grafted starch-polymer alloy is capable of imparting practical flexibility and toughness to moldings with no or only a little plasticizer. The polyester-grafted starch-polymer alloy comprises a blend of a polyester-grafted starch (a starch which has polyester graft chains on the starch molecule, with the terminal hydroxyl groups of the polyester graft chains and the hydroxyl groups connected directly to the starch entirely or partly blocked with the ester group) and an independent polyester (a polyester which is constructed of the same unit as said polyester graft chain, with its terminal hydroxyl groups entirely or partly blocked with the ester group) which are uniformly mixed together. A method of preparing the alloy and thermoplastic resin compositions containing the alloy also are disclosed.

Abstract: A starch derivative which, when incorporated with no or only a little plasticizer, yields moldings having good flexibility, toughness, and water-relating properties for practical use comprises an esterified, polyvinyl ester-grafted starch derivative which is formed by esterifying starch and grafting starch with a polyvinyl ester. The polyvinyl ester is derived from one or more saturated or unsaturated aliphatic acids or aromatic carboxylic acids having 2 to 18 carbon atoms.

Abstract: A method of preparing starch esters consists of combining starch with an esterification catalyst and then reacting the starch with a vinyl compound. The starch esters thus prepared and the compositions containing those esters have properties which are superior to the starch esters of the prior art.

Abstract: A starch derivative which, when incorporated with no or only a little plasticizer, yields moldings having good flexibility, toughness, and water-relating properties for practical use is an esterified, polyester-grafted starch which is formed by esterifying starch and grafting the starch with polyester. The esterification involves the introduction of one or more acyl groups consisting of saturated or unsaturated aliphatic acid groups or aromatic carboxylic acid groups having 2 to 18 carbon atoms and the polyester is one which is formed from one or more 4- to 12-membered lactones by ring-opening polymerization, with the terminal hydroxyl groups being almost completely blocked by esterification.