Synthesis and Interfacial Adhesion Interaction of Borate Ester Bonding Agents Used for HTPB Propellants

Abstract

The external monomers N‐methyl‐N,N‐diethanolamine, N‐butyl‐N,N‐diethanolamine, N‐(2‐cyanoethyl) diethanolamine, and N,N‐dihydroxyl‐3‐aminmethyl propionate were synthesized by modification of diethanolamine to evaluate the effects of external monomer molecular structure on the interfacial interactions of borate ester bonding agent (BEBA) applied in four‐component hydroxy‐terminated polybutadiene (HTPB) propellants. The compounds were characterized by IR and NMR spectroscopy. A series of BEBAs were synthesized using the as‐synthesized external monomers as well as diethanolamine. The interfacial interactions are evaluated using thermodynamic methods including acid‐base interaction enthalpy and wetting theory among the components in HTPB propellants. The experimental results indicate that the addition of BEBA‐3 prepared from N‐(2‐cyanoethyl) diethanolamine can significantly improve the interaction ethalpies and surface properties of the components in HTPB propellants. The results from the mechanical properties testing and SEM observations are in accordance with the results from the thermodynamic analysis of the interfacial adhesion interactions.

Study of the Interfacial Interaction Performance of Branched Bonding Agents and CL-20

“…Kim confirmed that NPBAs with cyano, ester and hydroxyl groups had a high affinity for the HMX particles, and the addition of NPBAs to HMX-filled poly(ethylene glycol) (PEG) binder remarkably increased the strength of the propellant [12,17]. Since then, many types of macromolecular bonding agents have been synthesized and applied [18,19,20,21], following the design idea of NPBAs. Chen [22] synthesized a series of dodecylamine-based bonding agents with the end groups substituted with cyano, ester and hydroxyl groups, which showed a good affinity with RDX and enhanced the mechanical properties of the HTPB propellant.…”

Research Advances in Bonding Agents for Composite Propellants

“…Cui et. al reported four types of borate ester with N‐methyl diethanolamine, N, N‐2 hydroxyethyl n‐butyl amine, N‐(2‐cyanoethyl) diethanolamine, and N, N‐2 hydroxyethyl ethyl amide as intermediates obtained from reactants diethanolamine, 1‐bromobutane, acrylonitrile, and glacial acetic acid, respectively (Scheme ). Mechanical properties show higher performance for polar bonding agent, as it interacts with the polar moieties of AP, and RDX.…”

“…Thus, bonding agents prepared from acrylonitrile and glacial acetic acid results in better processing and mechanical properties relative to other two bonding agents which have non‐polar alkyl groups. The Cui and co‐workers have investigated the molecular structure, molecular dynamics and mechanism through inverse gas chromatography for the mentioned borate esters.…”

“…The results show that −CH 2 CH 2 CN modified group gives prominent results in interfacial interaction studies and EDS studies. Furthermore, SEM and contact angle studies reveal that wetting properties are improved which reflects in the enhanced mechanical performance of AP and RDX based composite propellant . The interaction studies through molecular design were further extended to HMX.…”

Improvement of Interfacial Properties Between Cis‐1,4‐polybutadiene Rubber and HMX Crystal

“…One of the common methods is adding a bonding agent to composite particles, which can improve the coating effect of the binder on the explosive crystals and enhance the mechanical properties [13][14][15][16][17] . Zhang et al [18,19] . Modified the polybutylene adipate borate to improve the interfacial interaction, the results show that the effect of CH 2 CH 2 CN on the interfacial interaction is obvious.…”