Green materials from added-lignin thermoformed pulps

Abstract

In this article, added-lignin thermoformed pulps (ALTP) were explored as a new alternative for green materials. Technical lignin was added to mechanical pulp and subsequently thermoformed, yielding a biobased material with lignin contents above natural levels. This material was tested for its mechanical properties, water-uptake, and density. In addition, FTIR and TGA-DSC were used to characterize the lignin samples, i.e., Soda, Kraft, and hydrolysis lignin, as well as lignosulfonates. The material properties were significantly changed at 20 – 40 wt% added-lignin per dry fiber. Lignin addition increased density and reduced water-uptake and wettability. The effect on mechanical properties could vary, however, pure lignin had a more beneficial effect than hydrolysis lignin containing residual cellulose. Higher stiffness was observed for the pure lignin samples at constant or decreasing tensile strength. In conclusion, ALTP is a promising material for developing new pulp products and plastics-replacements, where the ratio and type of added-lignin may be used to fine-tune the desired characteristics.