Today's KNOWLEDGE Share : Renewable resources based phenolic resin

Renewable resources based phenolic resin

The conventional phenolic resin was prepared from formaldehyde and phenol. Formaldehyde used as a raw material in phenolic resins having high toxic nature. Which damages human eyes, and skin, and causes harm by inhalation.In comparison with the others referenced above, furfural is a sort of sustainable heterocyclic aldehyde with a brilliant industrialization prospect. It is primarily yielded from biomass wastes, for example, corncobs and sugarcane bagasse as of now, which is likely use to replace formaldehyde in the synthesis of phenolic resins. In a furfural structure, a furan ring with an aldehyde functional group is attached to in the second position. The replacement of formaldehyde by furfural promotes the thermal stability of the phenolic resin.

Among the agricultural byproduct, Cashew nutshell liquid (CNSL) is the byproduct of the cashew industry and one of the renewable resources is special because it contains cardanol, anacardic acid, which is a phenolic lipid, and cardol, and other chemical compounds are also found in cashew nuts.Riya Srivastava et. al. was a renewable-based resin synthesized by using materials such as cardanol and furfural. They came to the conclusion that the produced cardanol resin can be used as a substitute for phenol resin based on petrochemical derivatives.The tensile and flexural strength of the resin reduced as the amount of cardanol increased when phenol was substituted for it in different molar ratios with formaldehyde. After that, both novolac and resol resins were synthesized with partial substitution of phenol with cardanol. The cardanol-formaldehyde resin was replaced with furfural to enhance its properties. After that substitution of furfural, an increase in mechanical, chemical, and curing properties of cardanol-furfural resin was observed.

Functionalization by Epoxidation

Epoxy phenolic resin is formed by the potential reaction of the epoxide functional group with the hydroxyl group in phenolic resin. Therefore, increasing the functionality of the resin increases its ability to cross-link, creating a more ground polymer with stronger resistance properties. Phenolic resins by themselves produce a high degree of crosslinking through thermosetting, which has high resistance properties to chemicals and water. In these phenolic resins, the polymer repeating unit generated from polymerization may still contain unreacted hydroxyl group (-OH) (C6H5OH). Epoxy phenolic resins change this condition by adding an organic group, such as epichlorohydrin (CL-CH2-(C2H3O)), that has an epoxy-functional group. K. Shukla S. K. et. al. Modified cardanol-based phenolic resins were used with different proportions of epichlorohydrin and functionalized resins were prepared. They studied that, an eco-friendly high-performance thermosetting bio-based epoxy resin is an environmentally friendly alternative compared to commercial epoxy resin.

source:www.orientjchem.org/ Institute of Science and Technology for Advanced Studies and Research (ISTAR)