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Hydroxy-terminated polybutadiene (HTPB) is commonly used as a binder system in rocket propellants and plastic bonded explosives (PBXs). As such, the investigation of this material under high-strain-rate and shock-loading conditions is of importance if the response of propellants and PBXs is to be understood. Therefore, the Hugoniot of two different HTPB compositions has been investigated, using manganin stress gauges. Both materials have a linear Us–up relationship, with the material having a higher plasticizer content having a lower value of c0. It has been suggested that additions of plasticizer increase the compliance of the material. In addition, in one composition, shock recovery experiments have been performed. Results indicate that no changes in glass transition temperature, decomposition temperature, or molecular weight occur in the range of shock stresses investigated.

Publicly available video recordings of the explosion in Beirut on August 4, 2020, were examined and from them it was possible, in conjunction with the well‐known Google Maps website, to obtain estimates for the locations of the observers’ cameras with respect to the blast, and estimates for the blast wave arrival time. A publicly‐available blast wave calculator was then used to estimate the size of the explosion in terms of the equivalent quantity of TNT that would produce the same blast wave arrival time at the observers’ distance. This work estimates the Beirut explosion to have been equivalent to 637 tons TNT, with a lower bound estimate of 407 tons and an upper bound estimate of 936 tons.

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The effect of particle size on the shock response of three soda-lime glass-hydroxyterminated polybutadiene composites has been investigated. While the shock velocity–particle velocity relationship has been shown to be nearly identical in all three materials, thus indicating that the hydrodynamic response is particle size independent, the shock stresses have been shown to be strongly dependent upon particle size. It has been proposed that this be due to the nature of the microstructure, with the larger particles restricting flow, and thus increasing shear strength, while the finer microstructure can flow as a whole.

Smart fluids in the form of electro-rheological (ER) fluids are among the most spectacular of the smart materials. ER fluids are typically suspensions of semiconducting, solid particles dispersed in an insulating carrier liquid, which show a dramatic increase in flow resistance when an external electric field is applied. This reversible and rapid change in flow properties has potential applications in many electronically controlled mechanical devices. This article gives a short overview of the field of ER materials and their basic properties. Current and future developments with particular attention to electrorheological polymers have been reviewed.

Isocyanates are highly reactive and toxic substances with severe health effects. Certain diisocyanates are restricted under REACH -The European Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals. Triethyleneglycol diglycidyl ether (TEGDGE) was used as an alternative to toxic isocyanates for the cross-linking of hydroxyl-terminated pre-polymers at 70 8C. The effect of three curing accelerators was determined while following the reaction kinetics by 1 H-NMR spectroscopy and differential scanning calorimetry (DSC). Polybutadiene (Poly BD R45HT-LO) and acrylic ester (HyTemp 4454) successfully cross-linked in 7-10 days to produce thermally stable net-works with low glass transition temperatures, as observed by DSC. Pre-aging the polybutadiene resin promoted crosslinking with TEGDGE. Four energetic compositions were then prepared using cyclotrimethylenetrinitramine (RDX) and pentaerythritoltetranitrate (PETN) as fillers, and polybutadiene (Poly BD R45HT-LO) and acrylic ester (HyTemp 4454) as binders. Both binders successfully cross-linked with TEGDGE in the presence of RDX and PETN, but only PETN was found to be chemically compatible with the crosslinked polymers. These results show that TEGDGE is suitable as a replacement for toxic isocyanates for the cross-linking of hydroxyl-terminated polyols.