RESUMEN
Thermal kinetic parameters are important for establishing the relationship between the aging process, time, and temperature, which would help predict the thermal aging lifetime and stability in the application of polymer materials. We developed a multi-channel in situ detecting device, which provided an efficient method for IR spectrum measurement. The thermal aging process of polyvinyl butyral (PVB) at several constant temperatures (100 °C, 110 °C, 120 °C, 135 °C, and 150 °C) had been studied by the multi-channel in situ infrared reaction device. The kinetic parameters (Eα) were calculated from the absorbance intensity of -C-O-, -C[double bond, length as m-dash]O, -CH3, and -OH. The -OH proved to be the active site of PVB during thermal aging, and a possible thermal aging mechanism of PVB was proposed. We proved the method using a combination of a multi-channel in situ reaction device and FTIR was suitable to study the aging mechanism and kinetics of polymers.
RESUMEN
2,6-Diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a representative of the new generation of low-sensitivity energetic materials and has been applied extensively in formulations as an insensitive high-energetic ingredient. Although the initial thermal decomposition mechanism of LLM-105 has been studied based on quantum chemical calculations, the internal mechanism of the two-step thermal decomposition still lacks experimental research. Thus, this study involves a detailed experimental study to reveal the mechanism of the two-step thermal decomposition of LLM-105. The results showed that LLM-105 decay was a consecutive reaction. The first-step reaction dominated the early stage of the LLM-105 decomposition, and its products participated in the reaction of the second step. The cleavage of NO2 and NH2 groups of LLM-105 mainly occurred in the first step, while gaseous products NO and C2N2 were released during the second reaction step. The first-step reaction had a higher oxygen consumption rate and a lower carbon consumption rate, producing more heat due to more extensive oxidation of the carbon backbone. The difference in the oxidative ability and reaction rate between the two steps resulted in a two-step exothermic and mass loss behavior. This study provides further insights into the entire reaction process of LLM-105 and would be helpful for its better application and for the design of new explosives.
RESUMEN
The thermal decomposition process of 2,6-diamino-3,5-dinitropyrazine-1-oxide(LLM-105)under several constant temperatures (100 °C, 115 °C, 130 °C, and 145 °C) have been studied by a multi-channel in-situ reaction system. Almost 1000 spectra were obtained within 24 days by Fourier-transform infrared spectroscopy (FT-IR). The thermal decomposition activation energies (Eα) of C-NH2 and C-NO2 in LLM-105 were calculated by the Arrhenius equation to be 89.65 and 145.09 kJ mol-1, respectively. The thermal decomposition process of LLM-105 under long-term constant temperature is divided into two paths: intramolecular H-transfer and C-NO2 partition. It is feasible to study the aging process of materials using a combination of a multi-channel in-situ reaction system and FT-IR, which can effectively monitor the evolution of structure.
RESUMEN
IR spectra of TATB at different temperature were investigated for vibrational assignments. The results showed that the hydrogen bonding interaction of TATB was significantly weakened with increasing the temperature. Based on the frequency shifts of the hydrogen bonding interaction to several vibrational modes, 12 absorbance bands in the region 600-1700 cm(-1) were assigned to corresponding vibrational modes. In addition, Fermi resonance effect between NO2 and NH2 scissors was observed, and the enhancement of Fermi resonance effect caused the intensity of v3 (at 1545 cm(-1)) to grow during heating.
