Characterization of Subabul Heartwood and Sapwood Pulps After Cooking and Bleaching

Abstract

This study aimed to investigate the effect of cooking temperature (165 °C, 140 °C) on subabul heartwood and sapwood pulps separately, and the effect of bleaching on the mixed subabul wood pulp. The pulps cooked at 165 °C had high cellulose content, high water retention value and low lignin content, compared to those obtained at 140 °C. Microscopic analysis confirmed the integrity of the pulps obtained at 140 °C, while those cooked at 165 °C presented loose and collapsed fibres. The water retention value and the cellulose and ash contents of sapwood pulp were much higher in comparison to those of heartwood pulp, for both temperatures, and it could be due to the differences in their lignin and extractive contents. Bleached pulp had high cellulose content, high brightness and was thermally stable up to 300 °C. For packaging applications requiring processing temperatures of up to 600 °C, unbleached fibres are recommended due to the integrity of their cell wall. UV-visible spectroscopy data revealed that 2 h cooking time was sufficient for effective removal of lignin from the heartwood, but the situation was different in the case of sapwood.

Characterization of cellulose nano/microfibril reinforced polypropylene composites processed via solid‐state shear pulverization

“…The sigmoid at the end of the decomposition stage of α‐cellulose with a weigh loss of 10 wt% for CNF and LCNF and 18 wt% for microfibril (BWKP) could be due to the removal of lignin from the cellulose structure leaving cellulosic fibrils collapsed with micrometric scale pores that may be acting as a heat shield. [ 48 ] The composites showed two major weight loss events. The first stage in the range of 50–170°C with around 2% weight loss is due to the evaporation of water absorbed in the fillers.…”