Fire hazards of PMMA-based composites combined with expandable graphite and multi-walled carbon nanotubes: A comprehensive study

Abstract

Due to their environmentally friendly features, expandable graphite (EG) and carbon nanotubes (CNT) were widely used as an additive in the field of flame-resistant polymers. However, the addition of EG or CNT improves heat and mass transfer in polymers, which in theory might hasten the rate of flame spread and hence raise the fire danger associated with polymers. Thus, LOI, CCT, and horizontal flame spread tests were carried out to comprehensively reveal the effects of the addition of EG and MWCNT on the fire risk of thermoplastic polymers. Results show that EG and MWCNT were antagonistic when functioning in PMMA together, despite the fact that both of them had good effects on flame retardancy when acting in PMMA alone. Additionally, the addition of EG and MWCNT to the PMMA increases the flame height and hastens the flame spread. The comparison of results between LOI with CCT and the flame spread test shows the addition of flame retardants in thermoplastic polymers will diminish the hazard of fire ignition and heat release while raising the hazard of flame spread, which suggests the fire hazard of thermoplastic polymers with flame retardants deserve comprehensive assessment when new types of flame retardants to be created.