Hemicelluloses: Effects, Types and Their Applications as Dry Strength Polymers of Paper

Hemicelluloses are the second major compounds in the chemical structure of wooden fibers. The same with cellulose، hemicelluloses are carbohydrates، but unlike cellulose، which is a homopolysaccharide، hemicelluloses are heteropolysaccharides. The use of strength additives in papermaking process is important to ensure that the products are suitable for their specific purpose. Nowadays، strength additives are developed to produce papers with specific strength and surface properties، by minimum quantity of cellulosic fibers. More reasons in using hemicelluloses، as dry strength additives، are due to many free hydrogen and hydroxyl groups available in their chemical structure. When a hemicellulose is adsorbed onto the cellulose fibers، these free hydrogen and hydroxyl groups provide more hydrogen bonding sites. The more hydrogen bonding sites available on the cellulose fibers، the more tightly bonded the paper web is obtained. Hemicelluloses are naturally interwoven in woods'' micromolecular structure، which indicates a strong relationship between them and cellulose. Xyloglucans and galactomannans are examples of hemicelluloses that can be accumulated in seeds of many plants. Guar gum and starch are polysaccharides currently used as wet-end additives in papermaking. In this study، the hemicelluloses: their effects، types and their applications in papermaking are investigated.