Synthesis, characterization, thermal properties and flame retardancy of a novel nonflammable phosphazene-based epoxy resin

• Published in: Polymer degradation and stability Vol. 94; no. 4; pp. 617 - 624
• Main Authors: Liu, Ran, Wang, Xiaodong
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-04-2009; Elsevier
• Subjects: Applied sciences; Chemical properties; Epoxy resin; Exact sciences and technology; Flame retardancy; Phosphazene; Polymer industry, paints, wood; Properties and testing; Synthesis; Technology of polymers; Thermal stability; Epoxy resin; Flame retardancy; Synthesis; Phosphazene; Thermal stability; Organic dianhydride; Nitrogen phosphorus heterocycle; Polyfunctional compound; Flame retardant; Guanidines; Curing (plastics); Experimental study; Property processing relationship; Phosphorus polymer; Thermal properties; Diamine; Novolac; Flammability; Phenoplasts; Chemical reactivity; Chemical synthesis
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2009.01.008

Hexakis(4-hydroxyphenoxy)-cyclotriphosphazene (PN–OH) was synthesized through nucleophilic substitution of the chloride atoms of hexachlorocyclotriphosphazene and reduction of the aldehyde groups, and its chemical structure was characterized by elemental analysis,
1H and
31P NMR, and Fourier transform infrared (FTIR) spectroscopy. A new phosphazene-based epoxy resin (PN-EP) was successfully synthesized through the reaction between diglycidyl ether of bisphenol-A (DGEBA) and PN–OH, and its chemical structure was confirmed by FTIR and gel permeation chromatography. Four PN-EP thermosets were obtained by curing with 4,4′-diaminodiphenylmethane (DDM), dicyandiamide (DICY), novolak and pyromellitic dianhydride (PMDA). The reactivity of PN-EP with the four curing agents presents an increase in the order of DDM, PMDA, novolak and DICY. An investigation on their thermal properties shows that the PN-EP thermosets achieve higher glass-transition and decomposition temperatures in comparison with the corresponding DGEBA ones while their char yields increase significantly. The PN-EP thermosets also exhibit excellent flame retardancy. The thermosets with novolak, DICY and PMDA achieve the LOI values above 30 and flammability rating of UL94 V-0, whereas the one with DDM reaches the V-1 rating. The nonflammable halogen-free epoxy resin synthesized in this study has potential applications in electric and electronic fields in consideration of the environment and human health.