Combustion and mechanical properties of natural rubber based on carboxyl modified carbon nanotubes and intumescent flame retardant

The flame retardant natural rubber (NR) composites were prepared using carboxyl modified multi-walled carbon nanotubes (CMCNTs) and traditional intumescent flame retardant with the ratio among ammonium polyphosphate (APP), melamine (MEL), and pentaerythritol (PER) of 3/1/1. The flame retardancy and thermal stability, and mechanical properties of NR composites were investigated by the LOI test, UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), and tensile test, respectively. The results showed that NR/IFR3/2.0CMCNT had good flame retardancy and past the UL-94 test V-2 rating. The peak of heat release rate (pHRR), the peak of smoke production rate (pSPR), and the total smoke production (TSP) of NR/IFR3/2.0CMCNT were lower than those of NR/IFR3, which were reduced by 4.4%, 12.1%, and 26.3%, respectively. In addition, CMCNTs can improve the elongation at the break of NR composites with the increase of CMCNTs under the condition of low load CMCNTs.

Automated summary

The study investigated flame retardant natural rubber composites using carboxyl modified multi-walled carbon nanotubes and traditional intumescent flame retardant, showing improved flame retardancy, thermal stability, and mechanical properties. The addition of CMCNTs and intumescent flame retardant led to reduced heat and smoke production rates, as well as enhanced elongation at break of the composites.