describe the invention examples of the synthesis of some of the various chemical species are given below unmodified starch has the structure shown in fig1 unmodified starches can differ in properties such as amylopectin amylose ratio granule dimension gelatinization temperature and molecular weight unmodified starches have very little affinity for fibers and modifications are widely done to extend the number of wet end starch additives available for use modifications to starches generally fall under one of the following categories 1 physical modifications 2 fractionation into amylose and amylopectin components 3 thermomechanical conversion 4 acid hydrolysis 5 chemical modifications 6 oxidation 7 derivatization and 8 enzyme conversion starch derivatives are the most common type of dry strength additive used in the paper industry the 1990 edition of the tappi publication u201c commercially available chemical agents for paper and paperboard manufacture u201d lists 27 different starch dry strength products starch chemistry primarily centers on reactions with the hydroxyl groups and the glucosidic c u2014 o u2014 c linkages hydroxyl groups being subject to standard substitution reactions and the glucosidic linkages being subject to cleavage in theory the primary alcohol at the c 6 position should be more reactive than the secondary alcohols at the c 2 and c 3 positions also it has.