Flame retardancy and thermal decomposition behavior of TPU/chitosan composites

Abstract

The application of chitosan (CS) in new materials is a hot research topic. In this paper, CS was used alone as flame retardant to prepare thermoplastic polyurethane elastomer (TPU) composites. Then, the flame retardancy and thermal decomposition behavior of TPU/CS composites were intensively investigated using cone calorimeter test (CCT), scanning electron microscope (SEM), microscale combustion colorimeter (MCC) test, thermogravimetric analysis/infrared spectrometry (TG‐IR), and gas chromatography‐mass spectrometry (GC‐MS). The results showed that CS can reduce the fire risk of TPU; 2.0‐wt% CS could make the peak value of heat release rate (pHRR) decreased to 457.2 kW/m2, reduced by 65.9% compared with TPU. And the peak value of smoke production rate (pSPR) and total smoke release (TSR) of the same sample was decreased by 79.4% and 54.2%, respectively. The TG‐IR and GC‐MS results confirmed that CS could promote TPU decomposition in advance, reacting with the decomposition products of TPU. Therefore, the production of combustible gas was reduced. The GC‐MS results showed that the production of isocyanates and ethers was reduced with the addition of CS. The digital photographs of SEM for the samples after CCT were shown that the char residue layer of the sample containing 2.0‐wt% CS was fibrous in shape. It could be speculated that the thermal decomposition products from TPU could react with CS at low temperature, which reduced the production of flammable gases. So CS had a good prospect in reducing the fire hazard for TPU.

Activated carbon and cellulose-reinforced biodegradable chitosan foams

“…However, when materials included chitosan, the production of flammable gas was suppressed, and the production of smoke and heat was reduced. Compounds that decomposed during thermal degradation were not mixed with oxygen for burning directly because of reaction with the amino group of chitosan (Jiao et al 2020).…”

Flame-Retardant Systems Based on Chitosan and Its Derivatives: State of the Art and Perspectives

“…The flame retardant features provided by chitosan (acetylation degree: 90%) were recently investigated by Jiao and co-workers [ 38 ], who incorporated the biomacromolecule into a thermoplastic polyurethane elastomer using an internal mixer. This is the only example of using chitosan (without any chemical modification) alone in a bulky polymer.…”

Surface modification on ammonium polyphosphate and its enhanced flame retardancy in thermoplastic polyurethane

“…In the past research, IFR has been documented suitable in many polymers. But for some polymer such as thermoplastic polyurethane (TPU), the IFR loading to satisfy fire‐resistant grade will bring inevitable elastic deterioration 5,6 . In our past work, less than 10 wt% APP helped TPU obtain UL‐94V‐0 rate in vertical burning test, unfortunately more than 50% elasticity was lost at same time 7 .…”