No abstract

The nitration of low molecular weight polybutadiene (PB) by a convenient and inexpensive procedure was investigated. To retain the unique physico‐chemical properties of the plasticizer, it was nitrated to an extent of 10 % double bonds. The product nitropolybutadiene (NPB) was characterized by FT‐IR and 1H NMR spectroscopy as well as GPC, DSC, and TGA methods. The kinetic parameters for the decomposition of NPB from room temperature to 400 °C were obtained from non‐isothermal DSC. The changes in glass transition temperature (Tg) and inert uncured binder systems were used for determination of its efficiency as plasticizer. NPB was used in cured and unfilled nitro‐hydroxyl terminated polybutadiene (NHTPB) binder. Isothermal thermogravimetric analysis (Iso‐TGA) was employed to determine the migration rate in cured and unfilled HTPB binder systems compared to the dioctyladiphate (DOA) plasticizer. It was found that the exudation of the NPB plasticizer is slower than that of the DOA plasticizer. Thus, the NHTPB/NPB binder system (binder/plasticizer) presents more convenient mechanical properties than HTPB/DOA and is a promising new energetic binder system for polymer bonded explosives.

In this paper the effects of particles configuration and particles distance on the heat transfer rate in a gas phase olefin polymerization reactor have been studied using the computational fluid dynamic (CFD) modeling approach. The goal was to determine the causes of particle overheating in this reactor. It has been shown that classic correlations such as Ranz-Marshall are sufficiently adequate when far away particles with no interactions are to be modeled. However, when particles are sufficiently close to having interactions, these correlations fail to satisfactorily predict the convective heat transfer coefficient. The results indicate an increase in particle distance leads to an increase in the Nusselt number on the particle surface. Therefore, for particles with a large distance and triangular or rotated square configurations, the local Nusselt number is closer to the Nusselt number for a single particle.

No abstract

Production of chlorpyrifos via the phase-transfer-catalyzed reaction of O,O-diethylphosphorochloridothioate and the sodium salt of 3,5,6-trichloropyridin-2-ol was reinvestigated. The formation of sulfotep (the major byproduct) and the yield are influenced by the nature and concentration of the catalysts, temperature, stirring rate, and time of the reaction. The elucidation of the roles of different parameters influencing the end of the reaction have permitted us to perform the synthesis of chlorpyrifos on bench scale (0.3 M scale) under optimized conditionssusing the minimum amounts of catalysts (0.5 mol %)swith 92% yield and 98.5% purity.