As a continuation of our effort to understand degradation mechanisms of a eutectic mixture of bis(2,2-dinitropropyl)acetal (BDNPA) and bis(2,2dinitropropyl)formal (BDNPF) (referred to as NP) under various environmental conditions, we investigated the thermal stability of NP under water and 74% relative humidity (RH) environments at temperatures below 70 °C. Based on a comprehensive characterization of samples aged over a period of two years, we conclude that in the presence of water the reaction pathways of the NP degradation are different from those observed in air or under nitrogen atmosphere. We found that the physical state of water molecules plays an important role as it determines the ability of oxygen to participate in the NP aging process. Based on the results obtained in Parts A and B of these studies, we conclude that the rate of NP degradation increases in the order: nitrogen < water < air < water vapor + air.

We investigated the chemical and thermal stability of a eutectic mixture of bis(2,2-dinitropropyl)acetal (BDNPA) and bis(2,2-dinitropropyl)formal (BDNPF) (referred to as NP) in various environments at temperatures below 70 °C. Changes in the chemical composition of aged samples were characterized using TGA, FTIR, GPC, ESI-MS, and 1 H NMR spectroscopies over a period of two years. The results show that the initial signs of NP degradation can be detected as early as 12 months at 70 °C in air. The initial step in the degradation is the elimination of HONO molecules, followed by the formation of nitroso-alcohol isomers. While the temperature plays a key role in determining the degradation kinetics of the initial stages, the absence or presence of oxygen determines the types and rates of formations of various isomers and intermediates during the thermal decomposition processes. In addition, oxygen accelerates the decomposition of the isomers and intermediates, whereas nitrogen has a stabilizing effect. BDNPA shows higher reactivity than BDNPF regardless of the aging conditions, which is attributed to the presence of an extra methyl group in its structure.

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To study the aging behavior of cured vinyl copolymer elastomer (VCE) under thermal and nitroplasticizer (NP) environment, we investigated the sorption and diffusion of NP in VCE and its composites. The sorption kinetics of NP into VCE and its composites with respect to filler concentration (0–80%) and temperature (18–70°C) were investigated by conventional gravimetric method. The NP sorption process is endothermic. Kinetic studies show that Fickian diffusion can describe the NP sorption in the VCE polymer. The samples with a high filler concentration show more complicated behavior at low temperature than that at high temperature. The present article discusses the dependences of diffusion coefficient and other related parameters on the polymer concentration and morphological structures of the samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40729.

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