Hydroxy terminated polybutadiene is a low molecular weight telechelic, translucent liquid rubber which finds a wide range of applications. The presence of double bonds and hydroxyl end groups can be effectively utilized to chemically modify into various functional groups such as epoxy, urethane, urethane methacrylate, carboxylic acid, ester, amine etc. Further, terminal carbon atom can be also be functionalized. In this review, preparation, properties, chemical modification and applications are discussed in detail.

Hydroxy Terminated Polybutadiene: Chemical Modifications and Applications

The ageing kinetics and mechanisms of a composite solid rocket propellant were investigated by monitoring unstressed propellant samples during prolonged storage at elevated temperatures. For samples confined under air during ageing, it was determined that oxidative cross-linking of the propellant binder was the main degradation mechanism over time. Plasticizer loss was a significant ageing mechanism only for those samples aged unconfined. In addition, there was an indication that ambient humidity had a significant but reversible effect on propellant mechanical properties. Arrhenius mathematical relationships were derived in order to ascertain the extent to which ageing was accelerated by increased propellant temperature. An activation energy for binder oxidation of between 71 and 74 kJ/mol was determined.

An Investigation of Composite Propellant Accelerated Ageing Mechanisms and Kinetics

Thermal decomposition and kinetics of plastic bonded explosives based on mixture of HMX and TATB with polymer matrices

R low mass and linear regression rates of solid fuels have been among the major drawbacks of classical hybrid rocket engine technology due to low density, inertness of conventional solid fuels, and the diffusion-controlled combustion process. The thermal degradation in the pyrolysis process of inert polymeric fuels has been considered to be one of the key processes occurring in hybrid rocket engines and solid-fuel ramjet engines [1]. The fuel-surface regression rate generated by this process is a very important design and performance parameter and is strongly affected by the operating conditions and the composition and thermophysical properties of the solid fuel. In addition, fluid dynamic, heat-transfer, and combustion processes in these solid-fuel systems are characterized by complex interactions involving numerous physical phenomena, simultaneously taking place in the combustion chamber and the fuel grain. These complex interactions include solid-fuel pyrolysis; metal vaporization for metallized solid fuels; oxidizer atomization and vaporization; gas-phase species mass diffusion; mixing and combustion between the fuel-rich and oxidizer-rich species; turbulent flow with mass addition; conductive, convective, and radiative energy transfer; and time-varying

Metals, Energetic Additives, and Special Binders Used in Solid Fuels for Hybrid Rockets

Studies on energetic compounds part 28: thermolysis of HMX and its plastic bonded explosives containing Estane

Des etudes TG-DSC realisees dans une atmosphere d'air ou d'azote sur des polybutadienes a terminaison hydroxy (HTPB) ont montre trois transitions qui ont entraine (1) un pic DSC exotherme et une augmentation de la masse lors de la TG a 170°C-240°C, seulement dans l'air, (2) un pic exotherme et une faible perte de masse dans l'air ainsi que dans l'azote, causes par la depolarisation, la cyclisation et la reticulation, et (3) une perte de masse due a la pyrolyse dans l'azote ou la combustion dans l'air, ce qui se traduit respectivement par un pic endotherme et un pic exotherme aigu dans les deux atmospheres. L'analyse FTIR des produits isoles lors de la TG a l'issue de l'augmentation de masse revele que de l'oxygene a ete ajoute a la structure butadiene. Les parametres d'activation d'Arrhenius (E et A) ont ete calcules pour l'addition exotherme d'oxygene. La methode selon Ozawa amelioree par l'equation d'approximation a deux termes pour la fonction p(x) (d'apres VSSC) a donne des resultats tout a fait comparables a ceux obtenus par la methode Kissinger.

Thermoanalytical Investigations on the Effect of Atmospheric Oxygen on HTPB resin

The paper describes an experimental procedure for the determination of overall kinetic parameters for the exothermic decomposition reaction of nitramine propellant. The kinetic parameters can be obtained through the use of differential thermal analysis (DTA), differential scanning calorimetry (DSC) or thermogravimetric analysis (TGA) methods. The procedure is applicable to reactions whose behaviour can be described by the Arrhenius equation and the general rate law. In the present work, DSC technique has been used for the evaluation of Arrehenius activation parameters and specific rate constants for thermal decomposition of a typical nitramine propellant. The kinetic parameters were computed by Ozawa and Kissinger methods for comparison. The activation energy value obtained from the Ozawa method is refined by an iteration procedure using Doyle approximation for the Arrhenius temperature integral p(x).

G. Viswanathan

Papers

Thermoanalytical Investigations on the Effect of Atmospheric Oxygen on HTPB resin

Kinetics of Decomposition of Nitramine Propellant by Differential Scanning Calorimetry