Acta Chimica Sinica ›› 2012, Vol. 70 ›› Issue (10): 1145-1152.DOI: 10.6023/A1202061 Previous Articles     Next Articles

Full Papers


武文明a, 张炜b, 陈敏伯c, 强洪夫a, 史良伟c   

  1. a 西安高科技研究所 西安 710025;
    b 国防科技大学航天与材料工程学院 长沙 410073;
    c 中国科学院上海有机化学研究所 上海 200032
  • 投稿日期:2012-02-06 修回日期:2012-04-18 发布日期:2012-04-20
  • 通讯作者: 史良伟
  • 基金资助:

    973 (No. 61338)资助项目

Theoretical Investigation of the Bond Dissociation of Hydroxyl Terminated Polybutadiene Binder and Effect on Mechanical Properties

Wu Wen-Minga, Zhang Weib, Chen Min-B Qiang Hong-Fuc, Shi Liang-Weia   

  1. a Xi'an Institute of High Technology and Science, Xi'an 710025;
    b College of Aeronautic and Material Engineering, National University of Defence Technology, Changsha 410073;
    c Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
  • Received:2012-02-06 Revised:2012-04-18 Published:2012-04-20
  • Supported by:

    Project supported by the National 973 Foundation of China (No. 61338).

HTPB-based adhesive network is usually used in cured solid propellants, in which the crucial issue involved in the storage and use is aging problem. The quantum chemistry calculation was used to analyze the relationship between homolytic bond dissociation energy of two HTPB-TDI binder models and bond decomposition caused by aging. The computational results were proved to be reliable and suitable for comparative analysis. The BDE values of C-O bonds connected with CH2 group were calculated to be minima, suggesting that they are the weakest bonds resulting in decomposition during thermal aging. The main degradation product is CO2. In the binder formed by the reaction of allylic primary hydroxyl of HTPB and TDI, the α-C-H is the weakest X-H (X=C, N) bond, suggesting that it is vulnerable to free radical attack accompanying the hydrogen transfer. The possible mechanism of aging for the easy-cleavage C-O bonds was proposed. The calculated activation energies of C-O bonds cleavage are approximately equal to the corresponding BDE values, indicating that the formation of radicals accompanies a barrier-free release of CO2 during thermal aging. The half-life time of such aging process was described by an exponential decay function of temperature. The aging of HTPB-TDI binder accelerates with increasing temperature. The radical recombination reactions of decomposed amino radicals and alkyl radicals are supported by thermodynamic data calculated. Molecular dynamic simulations were used to analyze the variation in the network structures and effect on mechanical properteis of HTPB-TDI binder models before and after aging. It is found that the density of the system decreases with release and diffusion of CO2, and the corresponding tensile modulus and shear modulus increase with aging.

Key words: HTPB-based binder, ond dissociation energy, echanical properties