Synthesis of K-Carrageenan Flame-Retardant Microspheres and Its Application for Waterborne Epoxy Resin with Functionalized Graphene.

Wang Wang,Teng Teng,Zhang Zhang,You You,Yang Yang

doi:10.3390/polym11101708

Abstract

In this article, the intumescent flame-retardant microsphere (KC-IFR) was prepared by inverse emulsion polymerizations, with the use of k-carrageenan (KC) as carbon source, ammonium polyphosphate (APP) as acid source, and melamine (MEL) as gas source. Meanwhile, benzoic acid functionalized graphene (BFG) was synthetized as a synergist. A “four-source flame-retardant system” (KC-IFR/BFG) was constructed with KC-IFR and BFG. KC-IFR/BFG was blended with waterborne epoxy resin (EP) to prepare flame-retardant coatings. The effects of different ratios of KC-IFR and BFG on the flame-retardant properties of EP were investigated. The results showed that the limiting oxygen index (LOI) values increased from 19.7% for the waterborne epoxy resin to 28.7% for the EP1 with 20 wt% KC-IFR. The addition of BFG further improved the LOI values of the composites. The LOI value reached 29.8% for the EP5 sample with 18 wt% KC-IFR and 2 wt% BFG and meanwhile, UL-94 test reached the V-0 level. In addition, the peak heat release (pHRR) and smoke release rate (SPR) of EP5 decreased by 63.5% and 65.4% comparing with EP0, respectively. This indicated the good flame-retardant and smoke suppression property of EP composites coating.

Highlights

Flame-retardant coatings can effectively reduce the flammability of the coated substrate, prevent the rapid spread of fire, or increase the fire endurance of the coated substrate [1,2,3]
Double-shell co-microencapsulated ammonium polyphosphate (APP) and expandable graphite were prepared by the in situ polymerization process with the use of melamine–formaldehyde resin and organic silicon, which improved the compatibility of APP with rubber, thermal stability, and flame retardancy of rubber [7,8]
KC-intumescent flame-retardant (IFR) and benzoic acid functionalized graphene (BFG) were added into the epoxy resin (EP) as a flame-retardant system to prepare a flame-retardant coating

Summary

Introduction

Flame-retardant coatings can effectively reduce the flammability of the coated substrate, prevent the rapid spread of fire, or increase the fire endurance of the coated substrate [1,2,3]. The intumescent flame-retardant coating consists of a polymer matrix, an intumescent flame-retardant (IFR) system, and a synergist. The traditional IFR system consists of the mixture of pentaerythritol (PER), ammonium polyphosphate (APP), and melamine (MEL) [4,5,6]. The traditional IFR has some unavoidable problems, for example, APP has poor compatibility with polymer matrix and is migrated. Microencapsulation of APP can effectively improve the compatibility between APP and polymers. Double-shell co-microencapsulated APP and expandable graphite were prepared by the in situ polymerization process with the use of melamine–formaldehyde resin and organic silicon, which improved the compatibility of APP with rubber, thermal stability, and flame retardancy of rubber [7,8]

Methods

Results

Conclusion