Most polymers are flammable, and dense smoke is easily produced during the combustion process. Under normal circumstances, the addition of traditional flame retardants is easy to produce a large load on the processing and mechanical properties of the polymer, the flame retardant efficiency is not high, and the smoke suppression performance is poor. Carbon-based materials have attracted much attention in recent years due to their low cost, abundant resources, light weight, high strength, and high modulus. A few carbon-based materials such as carbon nanotubes (CNT), graphene, carbon nanofibers (CNF), etc. It is often used in the industrial production of flame-retardant polymer composite materials.

　　Professor Chen Changkun from Central South University and Professor Shi Congling from the China Academy of Work Safety Science added CNT/CNF and IFR (APP and MNP) to the thermoplastic elastomer TPU material to study its flame retardancy and smoke suppression in TPU materials Synergistic effect.

　　 The researchers vacuum dried C-TPU, APP, MNP, CNT and CNF, and then used a twin-screw extruder to melt and blend the above materials in a certain proportion to process and prepare C-TPU composite materials with different proportions.

Subsequently, infrared-thermogravimetric analysis was used to evaluate the thermal stability of the composite material, and the cone calorimetry test, LOI test, UL94 test, etc. were used to introduce carbon nanoparticles and intumescent flame retardants on the combustion performance and inhibition of the material. The improvement of smoke performance is evaluated.

　　 TG-FTIR test results show that, compared with IFR-only composites, CNT/CNF/IFR-containing composites show higher thermal stability at high temperatures, and the maximum carbon residue can be increased by 54%. TG-IR results show that the flame retardant system can reduce the release of smoke particles by suppressing the volatilization of decomposition products, thereby producing a smoke suppression effect.

　　 Smoke density test (smoke density test) results show that the combination of CNT / CNF / IFR and the flame retardant C-TPU greatly improves the smoke release. The luminous flux of C-TPU-3 is increased by 64% and 93% respectively under no flame and flame state.

In addition, the CONE test showed that the combined use of CNT/CNF/IFR significantly reduced the pHRR and THR of the composite material. The pHRR value of C-TPU-3 decreased by more than 80%, and the flue gas emission was reduced by 50%; the LOI result improved significantly. The anti-dripping effect is improved. And when they are used in combination, the UL-94V test reaches the V-0 level under the same additive amount. The above test results show the good potential application value of the carbon-based flame retardant system.

Finally, through carbon layer scanning analysis, the researchers analyzed the possible mechanism of the system: the introduction of CNT/CNF/IFR can catalyze the formation of carbon in the early stage of decomposition, and form a network structure carbon layer in the later stage, thereby Promote the improvement of combustion performance and the improvement of dripping performance. In addition, the smoke suppression effect is effectively improved by suppressing the volatilization of decomposition products.

　　Content source:

　　Journal of Materials Science (Volume 53, Issue 8, April 2018, Page 6053-6064) (Note: The other authors are Dr. Zhang Xiaolong and Dr. Chen Jie)

　　 link to the original text:

　　https://link.springer.com/article/10.1007/s10853-017-1970-0

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