The CIMV lignocellulosic biorefinery: phenolic resins and polyurethanes synthesis using cimv linear lignins

摘要

The CIMV lignocellulosic biorefinery process, operating in organic acid media, produces pulp for printing and tissue papers, C-5 sugars and lignins. These lignins, extracted from straw under atmospheric pressure at 100℃, have low molecular weights (Mn = 1000), a regular chemical structure, determined by mass spectrometry (MS-MS - Maldi-TOF) (6) and a good functionality ( 4 to 5 mmol /g of lignins of total hydroxyl groups with 2 mmol phenolic group/g of lignins and 1 mmol carboxylic group/g of lignins ). This functionality allowed these linear lignins to be employed as macomonomers in the synthesis of different polymer materials. The direct replacement of phenol/formaldehyde oligomers by the CIMV lignins, without chemical modification, in this kind of resins exhibits satisfactory characteristics and gives good curing properties compared to the industrial phenolic resins. Another potential application of these lignins is the use as macromonomers in polyurethane synthesis. Polyurethanes can be obtained by treating these straw organosolv lignins with different isocyanates and the resulted films or foams were characterized by thermal analysis (DSC and TGA). The optimum amount of lignins was determined in function of the length of polyol chains. Polyurethanes with good thermal properties were obtained with 40% of CIMV straw lignins.