Comparative spectroscopic study of the modification of cellulosic materials with different coupling agents

The reactions of two cellulosic materials (an industrial cellulosic by-prod uct from a Kraft. pulp mill facility and a reference material) with three c oupling agents, used to improve compatibility between cellulosic reinforcem ents and thermoplastic matrices, were studied by diffuse reflectance Fourie r-transform infrared (DRIFT) spectroscopy and diffuse reflectance ultraviol et-visible spectroscopy. A maleated polypropylene wax (Epolene E-43(TM)) an d two silanes (N-2-aminoethyl-3-aminopropyltrimethoxysilane and methyltrime thoxysilane) were used as coupling agents. The two cellulosic materials rea cted in a similar way and the three coupling agents were covalently bonded to the cellulose. For the aminosilane, a reaction with cellulase involving a fraction of the amino groups was detected. A simple method, based on the analysis of the oxidation kinetics of treated and untreated materials, was developed to compare the degree of cellulose modification achieved by each coupling agent. The analysis revealed that a reduced fraction of the cellul ose reactive groups was converted by esterification with the maleated polyp ropylene. However, when applied in the appropriate conditions, the two sila nes converted most of such cellulose reactive groups. Finally, the reaction of cellulose with mixtures of coupling agents was studied. The aminosilane -treated cellulose reacted with the maleated polypropylene with formation o f amide links. (C) 2000 John Wiley & Sons, Inc.