Structure, mechanical properties, and gas permeability of elastomers based on polybutadiene and epoxy resin

Abstract

In this study, the structure, gas permeability, and mechanical properties of new elastomers based on liquid polybutadiene and epoxy resin were investigated by dynamic mechanical thermal analysis, thermogravimetric analysis, stress-strain analysis, and water-resistance and gas permeability tests. The results reveal that there was complete phase separation between the epoxy resin and polybutadiene. With increasing epoxy resin content, the glass-transition temperature of the soft segment varied little. These elastomers had tensile strengths of 6-10 MPa and ultimate elongations of 500-100% according to the different epoxy resin contents. Thermogravimetric analysis revealed that these elastomers had better thermal stability, with a 5% weight loss at a temperature of around 350 C. The gas permeabilities of these elastomers were measured to be 13.2-15.3 barrers for oxygen, 4.8-5.3 barrers for nitrogen, and 28-35 barrers for carbon dioxide at 23

Characterization of nanostructured epoxy networks modified with isocyanate-terminated liquid polybutadiene

“…However, so far no studies have been performed to establish unambiguously the nano-scale structure of these networks. Several other works in the literature report the use of polybutadiene functionalized with hydroxyl [50][51][52][53][54][55], epoxide [56][57][58][59], carboxyl [49,[60][61][62], and amine [63,64] as modifiers for the epoxy matrix, but all systems presented phase-separated morphology in the cured state because of the great incompatibility between polybutadiene and the epoxy matrix. In this sense, it appeared us that the confirmation of the totally nanoscopic character of the structure of the blends prepared by using PBNCO would be an interesting contribution for future development of technical applications.…”

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

“…When an external force is exerted on the HTPB propellant, the weak interfacial interaction between PU matrix and the solid filler can cause debonding of the solid filler and lead to the destruction of the propellant . Evidences indicated that the addition of bonding agents could significantly improve the interfacial adhesion interactions between the solid filler and PU matrix and improve the mechanical properties of the propellants . However, the capability of the bonding agents to improve the interfacial interactions is difficult to be estimated, and there are only a few and imprecise methods to design and select proper bonding agents that could really improve the interfacial adhesion interactions between the solid filler and binder matrix .…”

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1IntroductionAf our-component hydroxy-terminated polybutadiene (HTPB) propellant is an energetic composite consisting of oxidizing agents [ammoniump erchlorate (AP), hexogen (RDX)],c ombustion agent (aluminum powder), and HTPB polyurethane adhesive [1].T he surface properties of solid fillers and the interfacial adhesion interactions between HTPB polyurethane (PU) matrix and the surface of solid filler are importantf actors affecting the mechanical properties of HTPB propellant [2][3][4].W hen an external force is exerted on the HTPBp ropellant, the weak interfacial interaction between PU matrix and the solid filler can cause debonding of the solid filler and lead to the destruction of the propellant [5][6][7][8].E vidences indicated that the addition of bonding agents could significantly improvet he interfacial adhesioni nteractionsb etween the solid filler and PU matrix and improve the mechanical properties of the propellants [9][10][11].H owever, the capability of the bonding agents to improve the interfacial interactions is difficult to be estimated, and there are only af ew and imprecise methods to design and select proper bonding agents that could really improve the interfacial adhesion interactions betweent he solid filler and binderm atrix [12][13][14][15].The borate ester bonding agent( BEBA)i satypical bonding agent used in four-component HTPB propellants. The molecular structure is illustrated in Scheme1.T he hydroxyl and R 1 groups in the molecular structure of BEBA can interact with the solid fillers and the PU binder matrix leading to the enhancement of the interfacial interactions between the solid filler and PU binder matrix in HTPBp ropellants.

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