Conventional cast explosives (RDX/TNT) have major drawbacks of poor mechanical properties, shrinkages and higher sensitivity .These properties can be improved by applying plastic binder systems. The plastic-bonded explosive (PBX) is a composite material in which solid explosive particles are dispersed in a polymer matrix. The present paper describes the development of a nitramine/hydroxy-terminated polybutadiene (HTPB)-based castable PBX. The PBXs were processed as per standard procedures. Bimodal/trimodal particle size system was selected to reach a solid loading of 88 wt per cent. High solid loading was made possible through proper combination of coarse/fine ratio of solid ingredients, which was based on a number of tap density experiments. Processability of the binder system was studied by using various wetting agents as well as by selecting binder/plasticizer ratios. Mechanical properties of the PBXs were enhanced by different crosslinking agents. The explosive properties ofPBXs including detonation velocity , processability and sensitivity to different types of stimuli, were studied. The results show that PBXs can be manufactured with detonation properties better than those of composition B/octol with the added advantages of superior thermal and sensitivity characteristics.

Der EiduR des Dichtegradienten und der Porositkit a d die Leistung von druckgegossenen HMXITNT-HohlladungenPrikisions-Hohlladungen werden hergestellt unter Einsatz der Druck-GieBtechnik. Die Porositat und Lunker, die durch RBntgenaufnahmen in den Ladungen nicht nachgewiesen werden konnen, wurden die Leistung dieser Hohlladungen betrachtlich beeinflussen. Die Wirkung der Porosiat auf die Eigenschaften, wie Dichte, Detonationsgeschwindigkeit (VOD), CJ-Druck und Stachelgeschwindigkeit ist vorausgesagt worden. Dichteanderungen der Ladungen, die unter unterschiedlichen experimentellen Bedingungen hergestellt wurden, sind bestimmt und mit den in dieser Arbeit vorausgesagten Werten verglichen worden. L'influence du gradient de densit6 et de la prosit6 sur les performances de charges creuses HMX/TNT coulCes sous pressionDes charges creuses de precision sont fabriquees en utilisant la mkthode de coulee sous pression. La porosit6 et les vides, qui peuvent ne pas Ctre dttectes par des radiographies effectukes dans ces charges, pourraient avoir une influence considerable sur les performances de ces charges creuses. L'effet de la porosit6 sur les proprittks telles que la densite, la vitesse de detonation (VOD), la pression CJ et la vitesse de la pointe du jet a kt6 estim6. Les modifications de la densit6 des charges fabriqukes dans diffkrentes conditions experimentales sont dkterminees et comparees aux valeurs prevues dans ce travail. SummaryPrecision shaped charges are prepared adopting pressure casting technique. Porosity and voids in such charges which may not be detected by X-ray radiography would substantially effect the shaped charge performance. The effect of porosity on the parameters like density, VOD, CJ pressure and jet tip velocity have been predicted. Density variation in the charges prepared under different experimental conditions has been determined and compared with that of the predicted values in this paper.

Most high explosive compositions are organic in nature and they tend to undergo slow decomposition during storage under different environmental conditions. The decomposition degrade the molecular stability of the explosive, thereby resulting in reduced performance and service life. The knowledge of decomposition behaviour of the explosive mass determines the storage life of the composition. Hence, change in the chemical stability , sensitivity , mechanical strength and performance are of utmost importance in the prediction of storage life of explosive/munition systems. This paper presents the results on the rate of gas evolution, change in sensitivity, and thermal stability and weight loss of high explosive compositions, viz., Dentex and 1NT when exposed to elevated temperature. Based on the collected data, a tentative storage life for the aluminised (Dentex) composition has been computed to be 15 years. The data has been compared with 1NT , a standard explosive for assessing the storage life.The degradation phenomena of the compositions are determined with the help of several tests, including vacuum stability test (for measurement of volume of gas evolved), differential thermal analysis (DTA) (for knowing change it:a decomposition temperature) and gravimetric analysis and international heat test (for loss in weight and performanc(' "valuation). In addition, theoretical calculations are also used for determination of decomposition and thereby assessment of the life of an explosive. Activation energies are also. used to predict long-term storage life. The test assumptions are mostly based on Arrhenius type reaction rate equation I.

Explosive filling in small-calibre shaped charges is carried out by pressing technique. At present, pressing is carried out by single action method which suffers from a drawback of density gradient in the charge from the face of the tool. A new method-double action pressing-has been established which eliminates this problem. Filling quality of charge of 30 mm calibre prepared by this method especially with respect to the density gradient is presented and discussed.

Small calibre shaped charges are prepared by the pressing method. The shaped charge performance is considerably influenced by the density gradient which is an inherent drawback associated with the pressing method. A new method, double action pressing technique has been developed which overcomes this problem and is amenable for large scale production. Properties of the charges prepared by the different methods especially with respect to the den sity gradient and performance against targets are presented and discussed.