Title
Effect of recycling on fundamental properties of softwood and wheat straw pulp fibers and of handsheets made thereof
Authors
YANGMEI CHEN JINQUAN WAN QITANG WUYONGWEN MAand MINGZHI HUANG

Received April 1, 2014
Published Volume 50 Issue 9-10 October-December
Keywords recycling, properties, strength loss, water retention value, hornification, hemicelluloses

Abstract
The effect of recycling on the fundamental properties of hardwood and wheat straw pulp fibers and of the handsheets made thereof was investigated. Recycling tended to decrease the tensile strength and burst strength of both types of paper sheets, while increasing their tear strength. It clearly had no impact on the fiber length and fiber strength (zero-span tensile strength) of either wheat straw or hardwood pulps, however, the content of fines gradually decreased. The content of fines of hardwood pulp was larger than that of wheat straw pulp both initially and after recycling. The degree of polymerization (DP) of wheat straw and hardwood pulps significantly decreased at early recycling stages. Recycling also led to a decrease of the water retention value (WRV) and loss of hemicelluloses, which resulted in the decrease of recycled paper strength. Consequently, the strength loss of papers made from wheat straw and hardwood pulps depended on the decrease in fiber swelling (hornification) and in hemicelluloses content during recycling.