Lignin, a renewable waste material of pulp and paper industries, was analyzed through Fourier-Transform Infrared Spectroscopy (FTIR) and found to be structurally similar to kraft lignin. Surface modification by addition of benzoyl peroxide and subsequent heating at 70°C caused generation of new functional groups in lignin. Efficacy of the crude lignin as well as that of the modified variety as a filler in nitrile rubber (NBR) has been evaluated. Rubber vulcanizates were analyzed for physico-mechanical properties, oil and fuel resistance, and thermal stability, and compared with conventional fillers like phenolic resin and carbon black. Modified lignin has been found to produce superior elongation, hardness and compression set properties 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 black.

Nanocomposites of epoxy resin with montmorillonite clay were synthesized by swelling of different proportions of the clay in a diglycidyl ether of bisphenol-A followed by in situ polymerization with aromatic diamine as a curing agent. The montmorillonite was modified with octadecylamine and made organophilic. The organoclay was found to be intercalated easily by incorporation of the epoxy precursor and the clay galleries were simultaneously expanded. However, Na-montmorillonite clay could not be intercalated during the mixing or through the curing process. Curing temperature was found to provide a balance between the reaction rate of the epoxy precursor and the diffusion rate of the curing agent into the clay galleries. The cure kinetics were studied by differential scanning calorimetry. The exfoliation behavior of the organoclay system was investigated by X-ray diffraction. Thermogravimetric analysis was used to determine the thermal stability, which was correlated with the ionic exchange between the organic species and the silicate layers. The morphology of the nanocomposites was evaluated by scanning electron microscopy.

Toughening of epoxy cresol novolac resin (ECN) by carboxy terminated acrylonitrile‐co‐butadiene (CTBN) liquid functional rubber have been studied. Wide angle X‐ray scattering (WAXS) has been utilized to evaluate average molecular interchain spacing () from the strong maximum in the diffraction scan using Bragg's equation. The half‐width () of the maximum was used to qualitatively describe the distribution of . An increase in value signifies formation of a separate packing order as well as increase in the free volume. Fourier transform infrared spectroscopy (FTIR) studies convincingly establish that the interaction between oxirane group of epoxy and carboxyl group of CTBN are responsible for characteristic peak shifts in the blends compared to individual polymers. Physicomechanical properties of the blends e.g., the tensile, flexural and impact strengths showed an optimum concentration of CTBN (10 wt%) into ECN, which can offer maximum toughening. Cross sections of the composite specimens failed during impact testing have been critically studied through scanning electron microscopy (SEM) to gain insight into the mechanism of toughening and phase morphology.