Influence of Epoxidized Cardanol Functionality and Reactivity on Network Formation and Properties

• Published in: Polymers Vol. 12; no. 9; p. 1956
• Main Authors: Kinaci, Emre, Can, Erde, Scala, John, Palmese, Giuseppe
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 29-08-2020; MDPI
• Subjects: Acids; Aliphatic compounds; Bisphenol A; Chains; Crosslinking; Curing; Diethylene triamine; Elongation; Epoxy resins; Hardeners; Hydrogen peroxide; Mechanical properties; Network formation; NMR; Nuclear magnetic resonance; Phenols; Polymers; Renewable resources; Thermal stability; Thermomechanical analysis; United States > US
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym12091956

Cardanol is a renewable resource based on cashew nut shell liquid (CNSL), which consists of a phenol ring with a C15 long aliphatic side chain in the meta position with varying degrees of unsaturation. Cardanol glycidyl ether was chemically modified to form side-chain epoxidized cardanol glycidyl ether (SCECGE) with an average epoxy functionality of 2.45 per molecule and was cured with petroleum-based epoxy hardeners, 4-4′-methylenebis(cyclohexanamine) and diethylenetriamine, and a cardanol-based amine hardener. For comparison, cardanol-based diphenol diepoxy resin, NC514 (Cardolite), and a petroleum-based epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) were also evaluated. Chemical and thermomechanical analyses showed that for SCECGE resins, incomplete cure of the secondary epoxides led to reduced cross-link density, reduced thermal stability, and reduced elongation at break when compared with difunctional resins containing only primary epoxides. However, because of functionality greater than two, amine-cured SCECGE produced a Tg very similar to that of NC514 and thus could be useful in formulating epoxy with renewable cardanol content.