Thermal degradation and flame retardancy of fumaric acid in thermoplastic polyurethane elastomer

Abstract

In this paper, fumaric acid (FA) which was a new type of environmental and low-cost flame retardant was applied for thermoplastic polyurethane elastomer (TPU). The flame-retardant properties of TPU were tested using limiting oxygen index, cone calorimeter test, smoke density test, and thermogravimetric/Fourier transform infrared spectroscopy. It has been proved that FA could improve the difficulty of the ignition of the sample; the limiting oxygen index value of the sample (FA-4) increased by 29.7% when 2.0 wt% FA was added to TPU. The cone calorimeter test showed that FA can greatly reduce heat release and smoke production during the combustion process of TPU composites. For example, compared with the pure TPU, the peak heat release rate and total smoke release of the sample (FA-4) with 2.0 wt% FA were decreased by 50.8% and 51.5% respectively. The results of smoke density test showed that the luminous flux of the samples contained 0.5 wt% FA was increased by 79.2% compared with the pure TPU. The TG results revealed that the sample of FA-4 had higher char residue content compared with the sample of TPU. The results of thermogravimetric/Fourier transform infrared spectroscopy proved that FA could decrease the initial decomposition temperature for TPU composites and increase the release of CO 2 and H 2 O. All results of test illustrated that FA had good flameretardant effect on TPU. KEYWORDS environmental, flame retardant, fumaric acid, thermoplastic polyurethane elastomer 1 | INTRODUCTIONThermoplastic polyurethane elastomer (TPU) is a polymer formed by the copolymerization of diisocyanate and polyol, which is an elastic material between rubber and plastic. 1 Thermoplastic polyurethane elastomer has good prospects for development in daily life because of its superior performance, such as high wear resistance, high strength, high elasticity, and good hydrolysis stability. 2 However, as a combustible material, during the combustion process, TPU can produce a lot of smoke, heat, and poisonous gas, which easily cause the suffocation and even death of the personnel, and it has a serious droplet phenomenon, which limits its application in some fields. 3 Therefore, it is very important to improve the flame retardancy of TPU. [4][5][6][7] At present, the traditional flame retardants used for TPU include halogen flame retardants, phosphorus flame retardants, etc. 8,9 Halogen flame retardants are more popular in flame-retardant TPU because of the high flame-retardant efficiency, moderate price, and variety.However, halogen flame retardants will release corrosive gases such as halogenated hydrogen and a large amount of smoke under high temperature or open fire, which will bring great harm to the human body and the environment. 10 The phosphorus flame retardant has the characteristics of halogen-free and low toxicity, but it needs a high amount of addition, which has an effect on the mechanical properties of the materials. 11,12 As a result, the elongation at break of the composite system, especially the impact strength, will...

Phosphorus‐containing Salen‐metal complexes investigated for enhancing the fire safety of thermoplastic polyurethane (TPU)

“…The carbon surfaces of neat TPU and Salen‐DPCP‐M/TPU composites after cone calorimeter tests were investigated using SEM and EDS. Neat TPU shows a large number of bubbles and pores distributed on the surface (Figure 13A), suggesting that the thermal decomposition of TPU leads to the release of gases such as NH 3 , CO 2 , and water vapor through the pores into the air . The Salen‐DPCP‐Mn/TPU sample exhibits a loose spider web structure (Figure 13D), which allows gases, including CO, to be released more efficiently than from the TPU sample, and these findings are consistent with the results shown in Figure .…”

Flame retardancy and thermal decomposition behavior of TPU/chitosan composites

“…TG‐IR is used to analyze the gas products of samples during the thermal degradation process . Figure shows the TG‐IR spectra of TPU, TPU/CS2, and TPU/CH2 from 180 C to 700 C. Some volatile products of the composite could be determined by a specific strong infrared absorption peak, in which the gas phase components of the pyrolysis products were mainly H 2 O (3500‐4000 cm −1 ), CO 2 (2300‐2400 cm −1 ), hydrocarbon (3000 cm −1 ), and carbon‐oxygen double bond (1750 cm −1 ) . In the decomposition of TPU, hydrocarbons are the main component of smoke, and double bonds of carbon and oxygen represent the generation of diphenyl‐methane‐diisocyanate (MDI).…”

“…Volatile products of the TPU, TPU/CS2, and TPU/peak, in which the gas phase components of the pyrolysis products were mainly H 2 O (3500-4000 cm −1 ), CO 2 (2300-2400 cm −1 ), hydrocarbon (3000 cm −1 ), and carbon-oxygen double bond (1750 cm −1 ) 30. In the decomposition of TPU, hydrocarbons are the main component of smoke, and double bonds of carbon and oxygen represent the generation of diphenyl-methanediisocyanate (MDI).…”

Epoxy resin/tin ethylenediamine tetra‐methylene phosphonate composites with simultaneous improvement of flame retardancy and smoke suppression

“…Figure 11 depicts the FTIR spectra of the pyrolysis gases of EP and EP/TETP‐7 at different temperatures. As seen in Figure 11A, there are nearly no absorption peaks of organic volatiles from the decomposition of EP below 400°C, except some peaks at 3620 and 1640 cm −1 (H 2 O) and at 2362 and 2331 cm −1 (CO 2 ), which maybe result from the background disturbances 49 . At 450°C, some new peaks appear including 3377 cm −1 (N─H), 3014 cm −1 and 2962 cm −1 (C─H), 2177 cm −1 (CO), 1708 cm −1 (CO) and1500‐1300 cm −1 (aromatic compounds), indicating the fracture of backbones of EP matrix.…”