Cardanol-derived phenalkamines with totally different phosphorus oxidation states (Automotive-DCP-DETA and Automotive-DPC-DETA) had been synthesized by the Mannich response and used as curing brokers for diglycidyl ether of bisphenol A (DGEBA)-type epoxy prepolymers. 1H-NMR, 31P-NMR and FTIR spectra confirmed that Automotive-DCP-DETA and Automotive-DPC-DETA had been efficiently synthesized. DGEBA/Automotive-DCP-DETA and DGEBA/Automotive-DPC-DETA thermosets had been fabricated by thermally induced polymerization, whereas DGEBA/DDM was ready as a management pattern. The curing kinetics investigation indicated that the curing activation power of the DGEBA/Automotive-DCP-DETA and DGEBA/Automotive-DPC-DETA programs was greater than that of DGEBA/DDM due to the bigger steric hindrance of Automotive-DCP-DETA and Automotive-DPC-DETA. The cone calorimetry outcomes confirmed that the height warmth launch charge (PHRR) values of DGEBA/Automotive-DCP-DETA and DGEBA/Automotive-DPC-DETA had been 76.8% and 44.8% decrease than that of DGEBA/4,4′-diaminodiphenylmethane (DDM), respectively, and the whole warmth launch (THR) worth was decreased to 125.8 and 105.8 MJ m−2, respectively, from 159.9 MJ m−2 (DGEBA/DDM). These outcomes prompt a superior flame-retardant effectivity for Automotive-DCP-DETA over Automotive-DPC-DETA. The flame-retardant mechanisms of DGEBA/Automotive-DCP-DETA and DGEBA/Automotive-DPC-DETA had been studied by thermogravimetric evaluation coupled with Fourier remodel infrared spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. It may be inferred that the excellent flame retardancy of DGEBA/Automotive-DCP-DETA is principally ascribed to the formation of thermally secure phosphorus–oxygen constructions within the combustion course of, which is useful in enhancing the thermal oxidation resistance of char residues and thus enhancing the flame retardancy of epoxy resins. Tensile and flexural check outcomes confirmed that Automotive-DCP-DETA additionally had good strengthening and toughening results on DGEBA. This phosphorus-containing cardanol-derived phenalkamine (Automotive-DCP-DETA) imparted concurrently improved flame retardancy, and mechanical power and toughness to epoxy thermosets, which may very well be a renewable substitute for petroleum-based curing brokers in fire-resistant or corrosion-resistant coating functions.
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