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Molecular Dynamics of Neutral Polymer Bonding Agent (NPBA) as Revealed by Solid-State NMR Spectroscopy
Hubei Institute of Aerospace Chemotechnology, Xiangyang 441003, China
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, the Chinese Academy of Sciences, Wuhan 430071, China
Current address: Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
* Authors to whom correspondence should be addressed.
Received: 12 October 2013; in revised form: 3 January 2014 / Accepted: 16 January 2014 / Published: 22 January 2014
Abstract: Neutral polymer bonding agent (NPBA) is one of the most promising polymeric materials, widely used in nitrate ester plasticized polyether (NEPE) propellant as bonding agent. The structure and dynamics of NPBA under different conditions of temperatures and sample processing are comprehensively investigated by solid state NMR (SSNMR). The results indicate that both the main chain and side chain of NPBA are quite rigid below its glass transition temperature (Tg). In contrast, above the Tg, the main chain remains relatively immobilized, while the side chains become highly flexible, which presumably weakens the interaction between bonding agent and the binder or oxidant fillers and in turn destabilizes the high modulus layer formed around the oxidant fillers. In addition, no obvious variation is found for the microstructure of NPBA upon aging treatment or soaking with acetone. These experimental results provide useful insights for understanding the structural properties of NPBA and its interaction with other constituents of solid composite propellants under different processing and working conditions.
Keywords: bonding polymer; NPBA; structure; dynamics; solid-state NMR
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MDPI and ACS Style
Hu, W.; Su, Y.; Zhou, L.; Pang, A.; Cai, R.; Ma, X.; Li, S. Molecular Dynamics of Neutral Polymer Bonding Agent (NPBA) as Revealed by Solid-State NMR Spectroscopy. Molecules 2014, 19, 1353-1366.
Hu W, Su Y, Zhou L, Pang A, Cai R, Ma X, Li S. Molecular Dynamics of Neutral Polymer Bonding Agent (NPBA) as Revealed by Solid-State NMR Spectroscopy. Molecules. 2014; 19(1):1353-1366.
Hu, Wei; Su, Yongchao; Zhou, Lei; Pang, Aimin; Cai, Rulin; Ma, Xingang; Li, Shenhui. 2014. "Molecular Dynamics of Neutral Polymer Bonding Agent (NPBA) as Revealed by Solid-State NMR Spectroscopy." Molecules 19, no. 1: 1353-1366.