The lignins of different resources have been incorporated into various thermoset resins. Amorphous/heterogeneous nature and the complex structural composition of lignin result their behavior as either like a filler or like a reactive macromonomer in epoxy resin systems. Man- souri et al. [181] characterized the alkaline lignin and suggested their possible use for phenol- formaldehyde resin due to the availability of huge OH groups. Peng et al. [182] reported the fabrication of phenol-formaldehyde thermoset resin with lignin fillers and investigated their chemo-rheological properties. They found that the curing rate of the resin system decreased with increasing lignin content. Guigo et al. [183] fabricated the poly(furfuryl alcohol)/lignin compo­site resins and reported their mono phase behavior. This indicates the reactive monomer behavior of lignin in this thermoset system. Thielemans et al. [184] investigated the effect of kraft lignin on unsaturated thermosetting resin, which was a mixture of epoxidized soybean oil and styrene, for the fabrication of natural fibre reinforced thermoset composites. They found the complete solubility of lignin into the resin system and their result on natural fibre composites indicateed the compatibilizing effect of lignin. Nonaka et al. [185] reported the fabrication of a new resin system by aqueous mixing of alkaline kraft lignin with polyethylene glycol diglycidyl ether (PEGDGE), and a curing reagent. They identified the complete compatibility between lignin and PEGDGE though the studies on dynamic mechanical analysis.