Search

To improve the flame retardant performance of silicone foams (SiFs), this paper used modified Diatomate (Dia) and zinc borate (ZB) to prepare flame-retardant SiFs. The experiment applied to study the particle size distribution and surface element content changes before and after modification. Then, the influence of modified Dia and ZB on mechanical, flame retardant and smoke suppression properties were investigated by stretch test, limiting oxygen index (LOI) test, UL-94 test, cone calorimeter test, and smoke density analysis test. The mechanical properties showed that the tensile strength and elongation at break of SiFs with 3.75% modified Dia and 1.25% ZB were improved significantly. In addition, the LOI of SiFs with 3.75% modified Dia and 1.25% ZB was 33.6%, which passed UL-94-V-0. The peak heat release rate (PHRR) and total heat release (THR) were 48.3% and 52.2% lower than that of pure SiFs, respectively. At the same time, SiFs with modified Dia had a better smoke suppression effect. Particularly, the total smoke production (TSP) and smoke production rates (SPR) of SiFs with 3.75% modified Dia and 1.25% ZB were reduced by 98.2% and 84.6% compared with pure SiFs. [ABSTRACT FROM AUTHOR]

Water and pyrite (FeS2) in coal have great synergistic effect on coal self-ignite. In order to explore the characteristics of spontaneous combustion of high humidity and high sulfur coal, this paper selected different concentrations of water and pyrite to carry out thermogravimetric experiment and oxidation reaction kinetics analysis. The changes of coal samples oxidation under low temperature in mass and characteristic temperatures were studied through thermogravimetric (TG) analysis. The results indicate that the promoting effect of water on coal spontaneous combustion turns to restrain when it reaches 15%, and water and pyrite have substantial synergistic effect on coal oxygen absorption and mass gain stage (T3–T5 in TG temperatures), besides there is a range of water/pyrite contents (10–15 mass% water and 2–4 mass% pyrite) that have the largest effect on coal oxidation reactions. Through the analysis of oxidation reaction kinetics, it was found that the change rule of the apparent activation energy (Ea) in coal oxygen absorption and mass gain stage is similar to that of the thermogravimetric change, and it was the lowest at 2–4 mass% pyrite and 10–15 mass% water content. The reaction process of coal oxidation by water and pyrite conforms to the equation n = 4 Avrami-Erofeev, therefore water and pyrite just can promote coal oxidation externally. This research provides support for further understanding and control the influence of water and associated pyrite on coal self-ignite. [ABSTRACT FROM AUTHOR]

Coal fires are widespread in the coal–major producing countries, which causes serious environmental issues due to the high temperature and hazardous gases during coal combustion. Under oxygen–depleted atmospheres, the thermal behaviors and kinetic characteristics during coal combustion at high temperatures were paid more attention by the method of TG–DSC synchronous thermal analysis. The results indicate that the focused weightlessness and heat release processes became scattered under oxygen–depleted atmospheres, and the influence of oxygen concentration obviously increased when it was below 13 vol.%. The mass presented a linear correlation to the quantity of heat release, and the relationship between the mass and quantity of heat release showed stage characteristics with oxygen concentration. Moreover, the kinetic modes transformed from random nucleation and subsequent growth to contractive sphere, and the critical oxygen concentrations are consistent to these of thermal behaviors. These findings are significant for better understanding the characteristics of coal spontaneous combustion at high-temperature and under low-oxygen concentrations. [ABSTRACT FROM AUTHOR]

Coal spontaneous combustion (CSC) characteristics were identified by their different types of coal. In this study, the samples of lignite, non-caking coal, lean coal, and anthracite were chosen to investigate the variations of gaseous products and main active groups during the low-temperature oxidation. The law of indicator gases was obtained by temperature-programmed experiment, and active groups of four coal samples had specific and different probabilities of spontaneous combustion via Fourier transform infrared spectrometer (FTIR). The relationship between the indicator gases at different stages and the main functional groups of coal were explored by Grey correlation analysis. The results indicated that the characteristic temperatures of water evaporation and gases desorption period of four types of coal showed the similar variation with those in thermal storage stage (Stage 1). Moreover, temperature ranges (TRs) in Stage 1 of lignite, non-caking coal, lean coal, and anthracite were 20–60, 20–60, 20–60, and 20–80°C, respectively; TRs in Stage 2 were 60–100, 60–140, 60–120, and 80–200°C, respectively; TRs in Stage 3 were 100–180, 140–180, 120–180, and 200–240°C, respectively. Based on the correlation analysis, the hydroxyl, carboxyl, and methylene had a sound temperature correlation with indicator gases emission. Eventually, the prediction system for CSC during the low-temperature oxidation was revealed. [ABSTRACT FROM AUTHOR]

Coal spontaneous combustion (CSC) characteristics were identified by their different types of coal. In this study, the samples of lignite, non-caking coal, lean coal, and anthracite were chosen to investigate the variations of gaseous products and main active groups during the low-temperature oxidation. The law of indicator gases was obtained by temperature-programmed experiment, and active groups of four coal samples had specific and different probabilities of spontaneous combustion via Fourier transform infrared spectrometer (FTIR). The relationship between the indicator gases at different stages and the main functional groups of coal were explored by Grey correlation analysis. The results indicated that the characteristic temperatures of water evaporation and gases desorption period of four types of coal showed the similar variation with those in thermal storage stage (Stage 1). Moreover, temperature ranges (TRs) in Stage 1 of lignite, non-caking coal, lean coal, and anthracite were 20–60, 20–60, 20–60, and 20–80°C, respectively; TRs in Stage 2 were 60–100, 60–140, 60–120, and 80–200°C, respectively; TRs in Stage 3 were 100–180, 140–180, 120–180, and 200–240°C, respectively. Based on the correlation analysis, the hydroxyl, carboxyl, and methylene had a sound temperature correlation with indicator gases emission. Eventually, the prediction system for CSC during the low-temperature oxidation was revealed. [ABSTRACT FROM AUTHOR]