Lignin reinforced rubber composites

Lignin, a renewable waste material of pulp and paper industries, was analyz ed through Fourier-Transform Infrared Spectroscopy (FTIR) and found to be s tructurally similar to kraft lignin. Surface modification by addition of be nzoyl peroxide and subsequent heating at 70 degreesC caused generation of n ew functional groups in lignin. Efficacy of the crude lignin as well as tha t of the modified variety as a filler in nitrile rubber (NBR) has been eval uated. Rubber vulcanizates mere analyzed for physico-mechanical properties, oil and fuel resistance, and thermal stability, and compared with conventi onal fillers like phenolic resin and carbon black. Modified lignin has been found to produce superior elongation, hardness and compression set propert ies compared to phenolic resin but inferior to carbon black. Resistance to swelling, however, depends on the type of oil or fuel, and modified lignin always showed better properties than carbon black. Both thermo-gravimetric analysis (TGA) and thermo-mechanical analysis (TMA) showed highest thermal stability for the modified lignin followed by phenolic resin and carbon bla ck.