فهرست مطالب یدالله بیات

Polycaprolactone is a polyester binder that has a polar structure and is compatible with polar plasticizer. Also, due to ester structure, oxygen balance of this polymer is more suitable than HTPB, therefore, by combining these two binders as a copolymer, the disadvantages of HTPB are eliminated and its advantages are preserved. In this research work, triblock copolymer of PCL-HTPB-PCL is made by ring opening polymerization of caprolactone by HTPB (1000 g.mol -1 ) molecular weight as a initiator and 69% yield. This copolymer was characterized by (FT-IR) and 1H-NMR spectroscopy. The investigation of the curing conditions showed that the copolymer with IPDI and N100 isocyanate in a ratio of 80: 20 were properly cured. Finally, the compatibility of cured copolymer with high energy plasticizers was investigated using swelling test and it was found that PCL-HTPB-PCL copolymer is more compatible with Bu-NENA and TEGDN plasticizers than BTTN and TMETN.

Binders are one of the most key components of solid composite propellants used in the military and space research industries. In present research, a PPG-PTHF-PPG triblock copolymer was synthesized as a binder using polytetrahydrofuran as an initiator and propylene oxide monomer through the cationic ring-opening mechanism with suitable molecular weight and high efficiency. The synthesized copolymer was investigated and identified with tools such as IR, NMR, GPC, and DSC. In the next, the optimal conditions for copolymer synthesis, including the choice of solvent type, the amount of solvent and catalyst, and the duration of the reaction, were investigated. After taking steps of copolymer synthesis, the curing of the copolymer was tested by different isocyanate curing agents, so the optimal amounts of curing catalyst, chain extender, and R ( mixture of N-100 and IPDI isocyanate agents) were obtained. The mechanical properties of elastomers were also evaluated through preparing dumbbell-shaped elastomers, which showed an 80% increase in elongation compared to the HTPB sample.

Due to the important role of the binder of compound engines, many studies have been done to improve their mechanical and thermal characteristics. Glycidyl azide polymer is used as an energetic binder in compound engines. The aim of this research is to improve the thermal properties and glass transition temperature of this energetic binder by copolymerizing it. So, the energetic triblock the copolymer of polypropylene glycol- glycidyl azide polymer- polypropylene glycol (PPG-GAP-PPG) (Mn = 1800 g/mol) was synthesized. For this purpose glycidyl azide polymer (GAP) (Mn = 1006 g/mol) was synthesized by poly epichlorohydrin The GAP was used as the initiator. The GAP triblock copolymer was synthesized by ring-opening polymerization of polypropylene oxide in the presence of boron trifluoride etherate (BF3·OEt2) as the catalyst. The synthesized triblock copolymer was characterized by Fourier-transform infrared (FT-IR) and nuclear magnetic resonance spectroscopy. The glass transition temperature (Tg) of the triblock copolymer was characterized by differential scanning calorimetry (DSC). The DSC result showed that the glass transition temperature (Tg) of the triblock copolymer (Tg = −63 °C) is lower than the neat low molecular weight GAP (Tg = −53 °C). The thermal stability of GAP and PPG-GAP-PPG triblock copolymer was investigated using differential thermogravimetric analysis (DTG). The result indicated that the triblock copolymer is more stable than the GAP. To optimize the synthesis conditions of the triblock copolymer PPG-GAP-PPG synthesis condition, the effect of temperature and catalyst on molecular weight, and copolymerization efficiency were investigated. The best mood for the synthesis of the triblock copolymer was the yield (86%) at 10-15 ºC, and 1% by weight of the catalyst.The DSC result showed that the glass transition temperature of the copolymer (Tg = -63° C) was lower than that of low molecular weight glycidyl azide (Tg = -53 ° C). In order to optimize the synthesis conditions of PPG-GAP-PPG triblock copolymer, the influence of temperature and catalyst variables on molecular weight and copolymerization efficiency was investigated. The highest yield (86%) was obtained at 10-15 ° C and 1% of catalyst.

An efficient method for the synthesis of functionalized acenaphtho[1,2-b]indol-6b-ol derivatives were developed by the three-component reaction of acenaphthoquinone, barbituric acid, or N, N-dimethyl barbituric acid and aryl amines through sequential Knoevenagel / Michael / intramolecular N-cyclization sequences in ethanol. The reactions were carried out under catalyst-free and mild conditions. Advantages of this method include simple operation, catalyst-free, readily available starting materials, no need to column chromatography purification, and good to high yields (78 - 92 %). We confirmed the product by Fourier-transform infrared spectroscopy (FT-IR), Proton nuclear magnetic resonance (1H NMR), 13C nuclear magnetic resonance (13C NMR), and Mass spectrometry.

 Polyglycidyl nitrate (PGN) is used in the manufacture of propellant elastomers due to its properties such as highly energetic composition, high density, high oxygen balance, high explosion enthalpy and suitable compatibility with other components. In addition to its desirable properties, this polymer has disadvantages such as high glass transition temperature, poor mechanical properties, and low content of total solid. Also, its elastomer can undergo decuring process. To remedy these disadvantages, its copolymers are prepared using polymers with optimal thermal and mechanical properties.

In this research an energetic polypropylene glycol/polyglycidyl nitrate/polypropylene glycol (PPG/PGN/PPG) triblock copolymer was synthesized for the first time by cationic ring-opening polymerization of propylene oxide and PGN as macroinitiator, in the presence of boron trifluoride etherate (BF3.OEt2) as the catalyst. The effect of temperature and catalyst content on molecular weight and reaction yield was investigated. The obtained product was characterized by FTIR, GPC, and 1H and 13C NMR spectroscopy. Also, the thermal properties of the copolymer were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

The results showed that by increasing the temperature from 0 to 15°C, the conversion and yield increased. On the other hand, due to the low boiling point of propylene oxide (34°C) and the exothermic reaction, it is impossible to increase the reaction temperature above 15°C. By increasing the catalyst content from 0.2% to 1% by weight of the initiator, the polymer molecular weight increased and the highest yield was achieved in presence of 1% by weight of the catalyst, but by increasing the catalyst content from 1 to 1.5 weight percent, yield and molecular weight have decreased due to the development of adverse reactions. Studies by TGA and DSC showed an increase in thermal stability and a decrease in glass transition temperature of the copolymer compared to PGN.

A way to increase the specific impulse of solid propellants is using the energetic components such as energetic binder or energetic plasticizer in the propellant formulations. Hydroxy terminated poly butadiene (HTPB) is the one of pre-polymer which was specifically synthesized for its use as a binder in propellant. Incorporating PEG into HTPB chains increases the polarity of binder. In this study, in the first step, elastomers of HTPB/PEG blend are prepared and their mechanical and thermal properties are investigated. Then, the propellant based-on HTPB/PEG blend was prepared and its mechanical properties were compared to the propellant based-on HTPB binder. Incorporation of PEG into the binder, increases the stress and elongation of the propellant and also, influences its oxygen balance. In the solid propellant with 75% solid loading, theoretical and semi empirical specific impulse were increased to 7.9s and 6.9 respectively, by the addition of BuNENA.

Binder has a key role in the performance of composite propellants. The binders are classified into two neutral and high-energy categories. GAP is one of the most important energetic binders, but it has poor mechanical and thermal properties. The goal of this investigation is to improve the properties of GAP by copolymerizing it with polytetrahydrofuran. New energy triblock copolymer was synthesized using 1,4-Butanediol as a initiator and cation ring polymerization method using epichlorohydrin and tetrahydrofuran monomer in the presence of Boron trifluoride as a catalyst. The triblock copolymer w::as char::acterized using GPC, 13CNMR, ˡHNMR, IR. The thermal behavior of the synthesized polymer has been investigated using DSC-TGA, which results showed increasing the thermal stability and reducing the glass transition of the copolymer compared to GAP. Effects of three energetic plasticizers on viscosity and Tg of copolymer was studied. In addition, elastomers base on tri-block copolymer was synthesized using IPDI and N100 as curing agents and mechanical properties of these were analyzed.

Binder has a key role in the performance of composite propellants. GAP is one of the most important energetic binders, however, it has not suitable mechanical and thermal properties, and Tg. The aim of this investigation is to improve the properties of GAP by its copolymerization with polycaprolactone. New energetic triblock copolymer was synthesized with a yield of 91% using glycidyl azide polymer (GAP) as a macroinitiator and following cation ring polymerization method using caprolactone monomer in the presence of dibutyltin dilaurate as catalyst. The synthesized PCL-GAP-PCL triblock copolymer was characterized using GPC, 13CNMR, ˡ HNMR, IR and its thermal behavior has been investigated using DSC
TGA. The results show increasing of thermal stability and reduction of glass transition temperature of the synthesized copolymer compared to GAP.

In this study, a novel method to synthesis of 1,3,5,7-tetraacetyl octahydro-1,3,5,7-tetraazocine or 1,3,5,7-tetraacetyl1,3,5,7-tetraazacyclooctane (TAT) was used through acetolysis of 3,7-diacetyl-1,3,5,7-tetraazabicyclo-[3.3.1]nonane (DAPT) with acetic anhydride in the presence of sodium acetate as catalyst. Optimized reaction conditions were obtained by changing temperature, time and starting material concentrations. The advantages of this method are: elimination of byproducts such as 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT), recoverable waste streams, easy process and high yield. Also, there is no need for further purification of the product as the reaction leads to the formation of the pure product.

The binder is an essential ingredient of solid composite propellants. Today, the industrial military scientists have been focused on finding and developing the new energetic binders to enhance the performance of composite propellants. In this research, triblock hydroxyl-terminated polybutadiene (HTPB) with Glycidyl azide polymer (GAP) was synthesized as a new energetic binder. In the first step, PECH-PB-PECH copolymer was synthesized from the reaction of epichlorohydrin (ECH) with HTPB as a macro initiator in the presence of boron trifluoride etherate as catalyst; which then was characterized by FTIR, 1H-NMR spectroscopies. In the second step, the GAP-PB-GAP copolymer was synthesized by azidation of the triblock polyepichlorohydrin (PECH) and HTPB in the presence of sodium azide and mixed solvents of dimethyl acetamide and toluene at 70OC (90% yield). The effects of monomer, catalyst, and solvents on molecular weight, as well as the yield of copolymer (GAP-PB-GAP) were studied. The synthesized copolymers were identified by IR, NMR, GPC, DSC, TGA, viscosity and TLC (tin layer chromatography) methods. In addition, after finding the curing conditions, the mechanical properties of polyurethane-based GAP-PB-GAP (such as tensile strength and strain) were investigated.

Recognition of the molecular structures is the key point in understanding the performance of molecules; this is because of the existence relation between the structure and properties of a compound which links its microscopic and macroscopic to each other. The laboratory works usually are time consuming and expensive. QSPR is a method which help us to achieve the favoured data and information with serving the minimum cost and time. Because the laboratory works in the field of energetic materials are very costly and hazardous as well, in the recent years using the methods and models to predict the properties of these compounds have been wildly developed. Developing a model with good reliability and high predictive power needs to selection of proper molecular descriptors. A descriptor converts the chemical information of a compound to a number. This number should be able to present more information to us to interpret and predict the molecular properties of that given compound.

Glycidyl nitrate is a valuable chemical used for manufacturing poly (glycidyl nitrate) as an energetic polymer. In this study glycidyl nitrate was synthesized by ring opening reaction of epichlorohydrin by nitric acid as nitrating agent in the presence of several different catalysts, and the effect of different catalysts on one pot synthesis of glycidyl nitrate was evaluated. The main purpose of this research is to find an effective catalyst for improving the yield of the reaction under mild conditions. The result was show that the synthesis of glycidyl nitrate used of nitric acid and in the present of the nano Fe3O4 for the nitration of epichlorohyrin gave the highest yield towards the other catalyst. This catalyst in the presence of nitrating agent reacted smoothly and efficiently with epoxide under mild conditions to produce the glycidyl nitrate with 72% yield that in contrast to synthesis from epichlorohydrin without the presence of the nano catalyst with 60% yield increased about 12%. Its structure was characterized by Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance.

Polycaprolactones due to the polar groups in their structures are able to be mixed with other nitrate esters and thus are presented as suitable binders. In the other hand, polyglycidyl nitrate with ONO2 groups is a high energetic polymer; however, it has not suitable mechanical properties. Consequently, it is possible to use the favorable mechanical properties of polycaprolactone and energetic properties of polyglycidyl nitrate by the synthesis of the PCL-PGN-PCL three-block copolymer. In this research, the PCL-PGN-PCL three-block copolymer was synthesized for the first time. Firstly, polyglycidyl nitrate as a monomer was synthesized using epichlorohydrin (60% total yield of the reaction). Then, polyglycidyl nitrate was synthesized by using this monomer (70% yield). Finally, the new PCL-PGN-PCL three-block copolymer was synthesized by ring opening polymerization of caprolactone as monomer and polyglycidyl nitrate (PGN) as a macro initiator in the presence of dibutyl tin laurate as catalyst. The differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were performed to investigate the thermal characteristics of this copolymer (Tg -45.2 °C). In addition, there was one pick in the GPC chromatogram that proved the formation of PCL-PGN-PCL three-block copolymer. The PCL-PGN-PCL three-block copolymer was characterized by 1HNMR, 13CNMR and IR spectroscopy methods. In the last part, the synthesis process of the PCL-PGN-PCL three-block copolymer was optimized. The reaction conditions were optimized at 115° C for 19 hours using 1mol% of catalyst. Toluene was chosen as a solvent and the monomer was added gradually into the reaction media. The yield was 81%. Also, the molar ratio of monomer to initiator as 5:1 showed the best molecular dispersity.

4, 10- Dinitro-2, 6, 8, 12- tetraoxa-4, 10- diazaisowurtzitane (TEX) is well known as an efficient Insensitive high explosive. It was usually prepared via nitration of 1, 4- diformyl- 2, 3, 5, 6- tetrahydroxy piperazine reaction using a mixture of fuming nitricacid and concentrated sulfuric acid. However, these traditional liquid acids are toxic, corrosive and produce hazardous waste. In addition, these acidic mixture cause product decomposition and low yields despite their high catalyst activity. In this research the use of an efficient catalyst and mild reaction condition for TEX synthesis is reported for the first time. To access the high yields of ionic liquids, the ionic liquid, the amount of nitric acid, reaction temperature and reaction time have been studied. TEX was characterized by nuclear magnetic resonance spectra (NMR) and Fourier transform infrared (FTIR).

CL-20 is one of the well-known non-nuclear powerful energetic materials. TADB is an important intermediate in synthesis of CL-20. One of the significant steps in synthesis of CL-20 is application of palladium catalysis for debenzylation of TADB which has some disadvantages such as the high cost, need to special reactor and high cost and need to especial reactor, therefore scientists to find alternative catalyst to overcome these problems. Some of these reagents including cerium ammonium nitrate, cerium ammonium sulphate, potassium bromate, titanium thrichloride, and acidic reagent. It is notable that among these catalysts some of them such as cerium ammonium nitrate in pyrolidinium bisulphate ionic liquid, cerium ammonium nitrate in presence of oxidative reagents and titanium trichloride showed good results and the yield of tetraacetylhexaazaisowortzitane was desirable. The yield of 55% and the absence of organic solvent are the advantages in application of cerium ammonium nitrate in pyrolidinium bisulphate ionic liquid.

The aim of this research is to provide a convenient and relatively inexpensive preparation method for synthesis of 1،3،5-triamino-2،4،6-trinitrobenzene (TATB). TATB is a reasonably powerful explosive in which ts thermal and shock stability is considerably greater than that of any other known energetic material. It is used in military applications because of its significant insensitivity to thermal and shock environments. There is also interest in employing TATB in the civilian sector for deep oil well explorations where heat-insensitive explosives are required. 1،3،5-tribromo-2،4-dinitrobenzene (TBDNB) and 1،3،5-tribromo-2،4،6-trinitrobenzene (TBTNB) are the precursors for synthesis of TATB. The use of liquid acids such as sulfuric acid، as catalyst has some disadvetages such as corrosiveness and potential danger of explosion، toxic vapors and oxidative degradation of by-products. Heteropoly acids (HPAs) catalyze a wide variety of reactions in homogeneous or heterogeneous (liquid– solid، gas–solid or liquid–liquid biphasic) systems، offering strong options for more efficient and cleaner processing compared to conventional mineral acids. Therefore، in optimal conditions، TBDNB synthesized in the presence of heteropolyacid instead of sulfuric acid with 99% yield. We also synthesized TBTNB from TBB (in a one-pot procedure) using sodium nitrate and oleum ingredients with 60% yield. Ammonolysis of TBTNB finally produced TATB with 73% yield.

The HNIW with the chemical name 2,4,6,8,10,12-hexanitro 2,4,6,8,10,12- hexaazaisowurtzitane (more commonly known as CL-20) and with cage structure is the most powerful non-nuclear explosive materials. CL-20 can exist as four different polymorphic phases (α, β, γ and ε) at ambient temperature and atmospheric pressure having different density and sensitivity. ε morphology, with more density is less sensitive and more appropriate for military applications. In this paper, both the synthesis and crystallization methods for the preparation of ε-CL-20 is investigated and the effects of different parameters (solvent, temperature, and stirring rate) on the particle size of ε-CL-20 prepared from crystallization method were studied. It is shown that the best solvent for crystallization of ε-CL-20 is ethyl acetate. Heptane and chloroform are more convenient as antisolvents. ε-CL-20 was analyzed by different techniques as Raman and FTIR, SEM and XRD.

Energetic materials specifically explosives material used extensively both for civil and military applications. Therefore probability explosion energetic material is unavoidable. The need to development of energetic materials with high performance and greater stability to heat, thermally stable explosives, is given priority in research development energetic materials, which are safer, more reliable and more stable in the world applications recently. In this paper in addition to introducing thermally stable explosives structure and theoretical reasons for this stability, process manufacture, their properties and their stabilizing, their advantages and disadvantages and heat-stable methods for explosive, has been investigated. Some of suitable candidates of this group have been presented and their synthesis have been evaluated. Sensitivity to impact and friction TATB Is introduced as a measure to study the thermal stability. Furthermore, this review also describes the synthesis and properties of BTDAONAB which does not melt below 550 °C and it is considered a better thermally stable explosive than TATB. Finally, future of research in this field in the years to come is also highlighted.

1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB) is an explosive that possesses excellent thermal stability and sensitivity characteristics. These properties make TATB an attractive candidate for military and civilian applications. The aim of this study is the synthesis of TATB using available reagents and equipment. Thus, TNT was used as starting material in the synthesis of TATB following six steps including the oxidation of TNT to Trinitrobenzoic acid with Sodium dichromate and concentrated Sulfuric acid (yield 60%), decarboxylation to Trinitrobenzene (yield 68%), reduction to Triaminobenzene with metal powder and Hydrochloric acid or Hydrazine hydrate (yield 55%), protection of the Amine groups to synthesize Triacetamidobenzene and finally the nitration and deprotection reaction by hydrolysis reaction (yield 55%).

1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB) is an explosive that possesses excellent thermal stability, suitable density and lower sensitivity than the other standard explosives such as TNT. These properties make TATB an attractive candidate for using in military applications such as using in rocket warhead. In civilian sector TATB is used for deep oil well explorations where heat-insensitive explosives are required. TATB is also used for producing benzene hexamine, an intermediate in the synthesis of new and advanced materials. This compound used for preparation of organic ferromagnetic salts and heterocyclic molecule such as 1,4,5,8,9,12- haxa azatriphenylen. In this paper the chemical, physical and explosive properties of TATB have been reviewed and also analysis, identification and purification methods of TATB have been exposure. In addition, all synthesis methods of TATB have been introduced and their advantages and disadvantages have been compared. Finally the suitable method has been suggested.

Hexanitrohexaazaisowurtzitane (HNIW or Cl-20) is a high-energetic material with a cage structure. It is considered as the most powerful explosive. It is usually prepared via nitration of precursors with concentrated nitric and sulfuric acids. Herein, the usage of an efficient catalyst affording mild reaction condition for nitration of 2, 6, 8, 12-tetraacetyl-4, 10-diformyl-2, 4, 6, 8, 10, 12-hexaazaisowurtzitane (TADFIW) is reported. It has been well documented that heteropolyacids (HPAs) are an efficient and green catalysts. So here it is used as nitric acid activator. This strategy gave a milder condition for nitration reaction. Also the reactions can be carry out in a reasonably lower temperature. Using a new nitrating agents, concentrated sulfuric acid was eliminated from the reaction conditions. Meanwhile, the effect of the reaction temperature, time and other factors on the yield was investigated. The structure and purity of the compounds were characterized by elemental analysis, HPLC, IR and 1HNMR.

The formulation of the composite propellant is constituted of solid particles of (ammonium perchlorate) as well as metal fuel such as aluminum particles which are all dispersed homogenously within the Binder matrix. The availability of these solid particles affects the combustion mechanism of the composite propellant and causes the betterment in the performance parameters of rocket such as: increasing in specific impulse and burning time. The very accentuation of this paper is upon the acceleration effect and the derived phenomena of its (including agglomeration, pit formation by means of solid particles within propellant matrix, heat feedback, heat transferring -made of agglomerates- unto the surface of propellant which is being burnt) on the combustion mechanism of composite solid fuels which is conducive to increase in the burning rate of propellant. The rest of the paper is devoted to effects of miscellanies of factors such as pressure, static burning rate, and Al content upon increasing the burning rate of propellant.

A variety of polymer such as: ethyl cellulose, Cellulose acetate, polyester and etc have been served widely in insulation of double-base solid propellant. Proper insulation of double base propellants should have features such as: 1- low absorption NG; 2- Without or low producion of smoke; 3- good adhesion of insulator to propellants surface; 4- with suitable vanished and thermal parameters and etc. In this paper polymer used in insulation of double base propellant are reviewed and their physical and chemical characteristic are investigated and compared. Then hydroxyl terminated poly dimethylsiloxane was synthesized and the effect of temperature, reaction time, ratio of raw material, type and intensity of agitation, type of catalyst, solvent and quenching reagents on molecular weight of poly dimethysiloxane was studied. Also a new method for one step synthesis of a hydroxyl terminated polydimethylsiloxane is presented.

Tetrazoles are class of high nitrogen heterocycles. These compounds have C-N and N-N chemical bonds and thus have positive heat of formation, high density and specific high impulse. Tetrazoles have also high potential energy and low sensitivity to friction and shock and thus are used as green energetic materials in propellants, gas generators, explosives and pyrotechnics. Some of tetrazole derivatives are used as green primes now. Tetrazoles have some advantages compared to classical high energy materials such as lower toxicity, easier synthesis, cleaner and environmentally friendly decomposition. As a result they are good alternative for normal energetic materials. These compounds also are used as agricultural and pharmaceutical.