جستجوی مقالات مرتبط با کلیدواژه « پیونددهنده » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

The pot life of high-energy composites is one of the most important parameters of their manufacturing process. This is mainly influenced by the pot life of the binder system. In this research, the effect of different amounts of two types of curing catalyst (dibutyltin dilaurate (DBTDL) and triphenyl bismuth (TPB)) and different ratios of NCO / OH (R) on the pot life and physical properties of the polyurethane binder system  based on Hydroxyl-terminated polybutadiene (HTPB) was investigated. By increasing the amount of curing catalyst for both types of catalysts, the viscosity build-up of the binder system measured by the rotation viscometer was intensified. Also, increasing the amount of R from 0.8 to 1 increases the viscosity and crosslink density. Isophorone Diisocyanate (IPDI) binder system shows two distinct steps of increasing viscosity with two different rates, which is attributed to the presence of two different isocyanate groups in the molecular structure of IPDI with different reactivity. In the following, the physical properties and swelling of binder samples were investigated. Based on these results, binders with the highest crosslink density have the lowest swelling. The pot life value increases from R of 1 to 1.1, contrary to expectation, with pot life range value between R of 1 to 0.9. When using the DBTDL catalyst, it is clearly identifiable between different reactivity of two groups IPDI isocyanates, but when used with the TPB curing catalyst, this difference was not observed significantly.

Mechanical strength is one of the technical properties of heterogeneous catalysts which strongly depends on their synthesis and forming method. A serious problem with the use of Fe Fischer-Tropsch catalysts in a reactor is their tendency to undergo attrition. In this paper the factors affecting the extent of attrition of catalysts and specialy Fe Fischer-Tropsch catalysts in slurry reactors are initially introduced. The effect of spray drying along with silica binder on improvement of attrition resistance of co-precipitated Fe Ctalysts are presented afterward. It is shown that by spray drying method, under optimum operational conditions, production of spherical catalyst's granules with suitable density and strength is possible. Furthermore, strength of the granules would be enhanced using proper amount of silica binder.