Carboxymethyl Cellulose from Waste Lignocellulosic Pulps Produced by a Fast Soda/Aq Process

Abstract

Cellulose pulps were prepared from ground branch wood from pine and poplar and ground wheat straw by a fast soda/anthraquinone pulping. This process used high pulping temperatures and short residence times. Various combinations of temperature and time were used so that the H factor for pulps from pine and poplar was a constant 2700 while for pulps from wheat straw it was 270. The chemical composition of the resulting cellulose pulps was characterized and the possibility of synthesizing carboxymethyl cellulose from them was evaluated. The degree of substitution of our CMCs was found to be dependent upon the source of the lignocellullosic material, but independent of the pulping conditions for a specific substrate, (0.75 for pine, 0.82 for poplar and 0.89 for wheat straw). The rheological properties, the intrinsic viscosity and the molecular weight of the CMCs were found to be dependent on the pulping conditions for each lignocellulosic tested. The molecular weights of our CMC samples were 219,000 to 316,000 for pine, 335,000 to 375,000 for poplar, and 350,000 to 383,000 for wheat straw. The molecular weights were highest for the pulps cooked at low temperatures.