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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.

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Regarding new researches on chemorheology of energetic composites,it is determined that HTPB slurry should have convenient viscosity for ease of casting. In the other word, available time for appropriate casting of energetic composite after curative addition called pot-life. Long pot-life of HTPB binder system is necessarily for good processability and non-defect production of energetic composite grains. In addition to long pot-life, the physical-mechanical properties of HTPB energetic composite are of at most important. In this research, effect of  curative type (structure), casting temperature and the amount of DBTDL as a curing catalyst on chemorheological behavior of HTPB binder system and physical-mechanical  properties of energetic composite were investigated. Toluene diisocyanate (TDI), Isophorone diisocyanate (IPDI) and Hexamethylene diisocyanate (HDI) were selected in order to investigate the role of molecular structure of curing agent on Chemorheology of binder system and its slurry and also on physical-mechanical  properties of energetic composite. Moreover, temperatures of 40, 50 and 60 ˚C, were selected to study the effect of casting temperature on chemorheology. By decreasing each 10˚C of casting temperature, pot-life of binder system (IPDI and TDI) was increased about 10 min. Pot-life of binder system and energetic composite slurry based on IPDI in the presence of 0.005% DBTDL (the optimum content) at similar temperatures, showed the longest pot-life. The elastomer and energetic composite based on IPDI showed the most crosslinking density (CLD) and modulus in comparison to other curing agents with retain of tensile strength and adequate elongation.
 

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Hypothesis: The aim of this research was the investigation on kinetic of curing reaction of polyurethane binder based on hydroxyl terminated polybutadiene (HTPB). This reaction is of particular interest in advanced polyurethane composite materials.
Methods: HTPB diol was dynamically cured using differential scanning calorimetery (DSC) at different heating rates (5, 10, 20 and 40° C/min) with curing agents of Toluene Diisocyanate (TDI) and Isophorone Diisocyanate (IPDI) in presence and absence of Dibutyltin Dilaurate (DBTDL) catalyst. Kinetic parameters were calculated using Kissinger, Ozawa and isoconversion models. Urethane formation and viscosity build-up during cure reaction was studied by Fourier Transform Infrared Spectroscopy (FT-IR) and rotational visocmetery (RV) methods.
Findings: Results showed that activation energy, enthalpy, progress and the rate of reaction were influenced by type of curing agent and the presence of catalyst. Kinetic models showed activation energy was reduced about 1 kJ/mol at each 0.05 unit increase in the degree of cure. The activation energy of HTPB-TDI-DBTDL binder system versus degree of cure was reduced slower in comparison to HTPB-IPDI-DBTDL binder system. Decrease in activation energy at degrees of cure higher than 90% was intensified as probable diffusion of low molecular weight molecules into polymer chains. Enthalpy of reaction in HTPB-TDI-DBTDL binder system at heating rates of higher than 10° C/min was independent of heating rate, whereas in HTPB-IPDI-DBTDL binder system the enthalpy of reaction is highly dependent on heating rate. Chemorheological results showed that rate of curing reaction for binder systems are in the order of HTPB-TDI-DBTDL>HTPB-IPDI-DBTDL>HTPB-TDI.

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Research Subject: Among the burning rate catalysts (BRCs), ferrocene-based ones have shown better performance; but show volatility problem. Therefore, the use of ferrocene derivatives in order to make compatible with hydroxyl terminated polybutadiene (HTPB) prepolymer, is a novel trend which is recently interested in the related researches.
Research Approach: In this research, at first, vinyl ferrocene monomer (VFM) were in-situ homopolymerized to prepare poly (vinyl ferrocene) (PVF)in the presence of hydroxyl terminated polybutadiene (HTPB) prepolymer at three different conditions(with and without BPO as initiator and different amounts of VFM).Then, blend of PVF/HTPB were characterized using FT-IR, ¹HNMR and GPC analyzes. In the second part, energetic composites containing PVF/HTPB blend were prepared and thermal properties of prepared samples investigated and compared with energetic composites containing conventional catalysts using TGA.
Main Results: The GPC results showed that the main peak was larger and wider due to the increase in the average molecular weight of PVF/HTPB blend. Comparison of thermal analysis showed that energetic composites based on PVF/HTPB blend catalyst perform better than common catalysts and more reduces the AP decomposition temperature. PVF/HTPB blend act as a potential BRC in energetic composites in which migration problem reduce due to in-situ blending of VFM to HTPB.

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Research subject: The binder system based on of hydroxyl-terminated polybutadiene resin (HTPB), consist of dioctyl sebacate as a plasticizer (DOS), and toluene diisocyanate as the curing agent. Reaction between the HTPB hydroxyl resin group and the curing agent isocyanate group produces a polyurethane mesh to produce a rubber with the desired properties. In this research, the rheological and mechanical properties of the binder system were investigated and Physical properties compared in the presence of three chemicals retarder polymerization Polyurethane, oxalic acid, maleic acid and tetracycline.
Research approach: Oxalic acid, maleic acid and tetracycline alter the properties of the binder system by specific mechanisms. Oxalic acid and maleic acid react with the isocyanate group of the curing agent to produce amides and reduce the viscosity of the binder system. Due to its chemical structure, tetracycline reacts with the curing agent and prevents the development of the main reaction between the HTPB resin and the curing agent TDI and reduces the viscosity. Infrared Fourier transform (FT-IR) test was also used to investigate the functional mechanism of these compounds. In this test, the intensities of the spectra related to each sample were compared with each other and the type of function and mechanism of each of the oxalic and maleic substances and tetracycline were determined.
Main results: The structure of the reaction product between HTPB resin and oxalic acid, maleic acid and tetracycline with curing agent was determined and confirmed by FT-IR spectrum. In-situ FT-IR study showed reduction in isocyanate peak intensity after 60/90 min. Chemorheological investigation showed best performance at 0.05% concentration for all retardants, among them tetracycline, oxalic acid and maleic acid depicted 54%, 48% and 47% reduction in viscosity build-up; respectively. Adding 0.05% of tetracycline to binder system resulted in about 20% decrease in cross link density probably due to better interaction with curing agent which emphasized the best performance of 0.05%-tetracycline as retardant.
 

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"Ellipsis" brevity is a popular style in natural language. The brief words have compactness Without any defect. A comprehensive review of short discourses in language introduces two types of "linguistic Ellipsis" and "non-linguistic Reduction" brevities. According to semantic studies, "Ellipsis" is the omission of words based on co-text, but "Reduction" is the omission based on the context (=context of the situation and the audience's background knowledge). Linguistic Ellipsis can be discovered by the syntactic and rhetorical styles of the language, but non-linguistic Reduction can be identified only by considering the non-linguistic context. However, there is no specific rule for most interpretations provided for omitted cases. The Holy Qur'an, which was revealed in natural language, has used the style of elimination and reduction as a suitable tool to transfer the messages in the shortest phrases. Therefore, studying and knowing this knowledge becomes essential in understanding and interpreting the Quran, and neglecting it will damage understanding the meanings of the verses. The present article, using the knowledge of "applied semantics" introduces and analyzes the phenomenon of "reduction" along with "ellipsis" to understand and interpret the Holy Quran and has shown that the interpretation of the brief verses of the Quran needs non-linguistic knowledge. Thus, Quarn understanding is only possible by considering both linguistic and non-linguistic knowledge of the verses. Therefore, this truth establishes the possibility of understanding and interpreting all the brief verses of the Quran for the real "Quran Scholars", that is, the Holy Prophet and his Ahl al-Bayt (PBUT).