Thermal Degradation and Flame Retardance of Epoxy Resins Containing a Microencapsulated Flame Retardant

摘要

Two steps were used in the synthesis of a microencapsulated intumescent flame retardant (MIFR). First bis (1-oxo-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane-4-meth-ylol) phosphate melaminium salt (Melabis) was synthesized. Then the Melabis was encapsulated with melamine resin to obtain the MIFR. Its structure was characterized by XPS, SEM, and elemental analysis, and the factors affecting microencapsulation were identified and discussed. Epoxy resins (EP) were modified with the MIFR to prepare flame-retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOi) tests. The microcapsules (20% by weight) were added to EP in order to achieve an LOI of 29.5% and a UL 94 rating of V-0. The thermal properties of epoxy resins containing the MIFR were investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). The FR decreased by weight loss, R_(max) (the maximum weight loss rate), and the thermal stability of EP while promoting the formation of an effective charring layer. The char structures were studied by SEM.