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Volume 3, Issue 2 (12-2008)
Abstract
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Volume 4, Issue 1 (11-2009)
Abstract
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Volume 6, Issue 2 (12-2011)
Abstract
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Volume 7, Issue 1 (7-2011)
Abstract
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Volume 7, Issue 2 (9-2012)
Abstract
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Volume 8, Issue 2 (5-2012)
Abstract
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Volume 9, Issue 1 (9-2013)
Abstract
امروزه کاربردهای نظامی و غیر نظامی مواد پرانرژی رشد چشمگیری داشته است. با توجه به خطرات مربوط به ناپایداری و انفجار حرارتی مواد پرانرژی
لازم است تا قبل از تولید، مشخصههای ایمنی و پتانسیل خطر این مواد در مقیاس آزمایشگاهی مورد بررسی قرار گیرد. در این مقاله روشهای تعیین و
تحلیل پارامترهای مربوط به پایداری و انفجار حرارتی مواد پرانرژی مانند انرژی فعال سازی، ثابت پیش نمایی، دمای تجزیه خود شتابی، دمای بحرانی
انفجار حرارتی، زمان رسیدن به بیشینه سرعت، افزایش دمای آدیاباتیک، پتانسیل انفجار، شاخص پتانسیل خطر و سازگاری و عدم سازگاری مواد پر
انرژی با دیگر مواد در ارتباط با استفاده از گرماسنجی روبشی دیفرانسیلی ( DSC ( مورد بررسی قرار گرفته است. برای تعیین مقدار انرژی فعالسازی و
فاکتور فرکانس روش مکمل معرفی شده است که در آن ابتدا از روش های بدون مدل برای بدست آوردن مقدار Ea و مقایسه مقدار آن با روشهای
مدلدار استفاده میکند. در این روش از یک روش بدون مدل )ویازوکین( برای بدست آوردن مقادیر Ea استفاده میشود، که این مقادیر با مقادیر بدست
آمده از روشهای مدل دار )کوتس –ردفرن( مقایسه میشود. سپس با استفاده از مقدار انرژی فعالسازی به دست آمده، سایر پارامترهای ایمنی با
استفاده از معادلات مشخصهی هر پارامتر، به دست میآیند.
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Volume 9, Issue 3 (3-2014)
Abstract
عایق های بر پایه ترپلیمر اتیلن- پروپیلن- دی ان مونومر ((EPDM در صنایع موشکی کاربرد وسیعی دارند با این حال به لحاظ ساختار غیر قطبی آن، تلاش برای بهبود چسبندگی EPDM به سوخت جامد کامپوزیت بر پایه پلی یورتان از چالش های بزرگ صنعت مذکور می باشد. در این مقاله پارامترهای موثر در چسبندگی عایق به سوخت جامد بر پایه پلی یورتان مرور شده، روش های اصلاح سطح و توده عایق حرارتی بر پایه EPDM مطرح و پیشنهادهایی جهت افزایش چسبندگی عایق EPDM به ساختارهای پلی یورتانی ارائه شده است. روش های اصلاح ساختار نظیر واکنش پیوندزنی انیدرید مالئیک و وارد کردن پلیمرهای قطبی تر در کنار روش های اصلاح سطح نظیر روش های شیمیایی و انرژیتیکی از مهمترین تکنیک های مورد استفاده برای بهبود چسبندگی EPDM به ساختار های پلی یورتانی می باشند.
Mr Mansour Shahidzadeh, Mr Ehsan Kamali,
Volume 9, Issue 4 (12-2013)
Abstract
Glycidyl Azide Polymer is one of the most important energetic binders that is used in the composite solid propellant formulation. GAP is a unique binder with a positive heat of formation (+117.2 kJ⁄mol). In addition, GAP has good thermal and physical properties such as low glass transition temperature, low viscosity and high density compared to other energetic binders. GAP can be used as a binder and energetic plasticizer in preparation of PBX, composite and double base propellants lead to increase their performance. In addition, this polymer is used for preparation of low vulnerability ammunition (LOVA) and green propellants. In this paper, the studies on thermal properties of polyurethanes based on GAP by DMTA, DSC and TGA, and their mechanical properties such as tensile strength and strain and hardness have been investigated.
Mortaza Noamoz, ,
Volume 9, Issue 4 (12-2013)
Abstract
In order to preserve structure and also achieve the desired thrust rocket motor, engine Case temperature should be prevented increase excess.This operation the can be done by Insulation. EPDM rubber because of advantages such as low specific weight, improve aging properties, as long as thermal insulation for solid propellant motors case bond Introduced and its properties are investigated in this study. However these advantages, EPDM, a rubber is nonpolar and it weakens the adhesion composite solid propellant is based HTPB. According to importance of a strong connection between the insulation and solid propellant, different methods of modification of EPDM rubber surface and improve adhesion strength has been studied.
Mr Ehsan Kamali, Mr Mansour Shahidzadeh,
Volume 10, Issue 2 (12-2014)
Abstract
Glycidyl azide polymer (GAP) is a unique elastomeric binder with high heat of formation and high density due to enhanced thermal and performance properties of composite solid propellants. However, GAP has high glass transition temperature and poor mechanical properties that are limited its application as a binder in a composite solid propellant. In this paper , the efforts carried out on modification of mechanical properties and glass transition temperature of polyurethane based on GAP through preparing copolymer based on GAP using flexible back bone such as Polyethylene glycol (PEG), Polycaprolactone (PCP) and Hydroxyl terminated polybutadiene (HTPB) was reviewed and the results were investigated.
, Farideh Salarimanesh, ,
Volume 10, Issue 2 (11-2015)
Abstract
Hydroxyl terminated polybutadien that is known as HTPB resin is a liquid hydrocarbon polyol that is commonly used in preparation of solid composite propellants. Because of unsaturated nature of repeating unit of HTPB polymer , it has high potential for oxidative aging . In this paper ,we have investigated aging behaviors of two types of HTPB which having various content of phenolic antioxidant. For this purpose ,two samples of resin have stored at 60 °C and atmospheric pressure and change on their properties, such as peroxide value,hydroxyl value,epoxy number,viscosity and molecular weight have investigated.Under basis of results, we can conclude during the oxidative aging of HTPB, coupling of radical chain is the most important elementary reaction that occurred in HTPB resin and would change its properies.
Mansour Shahidzadeh, Foad Shaghayeghi Toosi, Ali Maghsoodi, Mahvash Zamani,
Volume 11, Issue 4 (12-2016)
Abstract
Composite propellants are often identified by the type of polymeric binder used. The most commonly used polyol in recent time is the Hydroxyl Terminated Polybutadiene (HTPB). In order to evaluate the quality of three types of HTPB prepolymer, their polyurethanes elastomers were synthesized by one shot polymerization and structure-properties relationships of the prepared polyurethane have investigated. For this purpose, firstly, chemical structure of HTPB samples is characterized by GPC and NMR spectroscopy and viscometery. Then the stress-strain study was carried out to explain the effect of soft segment functionality on the tensile behavior. It was found that the effective functionality of soft segments had subtle effects on the tensile strength and elongation at break. On the basis of results that are obtained from gel point study and tensile test, we can deduce that the effective functionality of three types of prepolymers increases in order HTPB1>HTPB2>HTPB3. By increasing the effective functionality, the molecular weight between junctions in polyurethane elastomer is decreased. Also, the result of tensile test can be modeled with money-rivilin equation. Experimental data for the money-Rivlin constants were found and it was shown that gte msEquation 12]>C1{C}{C} !msEquation]--> for HTPB1 and HTPB3 are greater than HTPB2. Furthermore, it was found that trapped entanglements and pendant chain can be accountable for the gte msEquation 12]>C2{C}{C} !msEquation]--> term of money-rivilin equation.
Yahya Ebrahim Abadi, Dr Masoud Mokhtary, Dr Mohammad Mehrshad, Dr Mahdi Abdollahi,
Volume 15, Issue 3 (5-2020)
Abstract
Despite the unique properties of epoxy resins, their use is limited in many cases due to their low impact resistance. One of the methods to overcome this limitation is to use compounds for increase Toughness such as carboxyl-terminated butadiene acrylonitrile (CTBN) (94% Wt) in the epoxy matrix. In this study, investigated the curing reaction of CTBN with 1,2,7,8 diepoxyoctane (DEO)(5% Wt) in the presence of two types of amine 1,1′-Isophthaloyl bis(2-methylaziridine) (HX-752) and triethanolamine (TEA) as catalyst. In order to evaluate the performance of the proposed binder, elastomers with different formulations were prepared and tested for mechanical and thermal properties. The results of mechanical and thermal properties of elastomers produced in the presence of TEA in comparison with HX-752 showed that the tensile properties(234.17%),cross-linking density(111.78), storage modulus, and glass transition temperature(43.9°C) has increased. Due to the improvement of the properties created in this research, it is predicted that the created binder can be used in the formulation of composite solid propellants and PBX explosives, as well as liner and insulation coatings with proper performance.
Dr Mohammad Ali Zarei, Dr Ghasem Oskueyan, Ms Asiye Asgari Khaiarbadi, Dr Dariush Fallah, Mr Milad Sadri Khanloo,
Volume 19, Issue 3 (12-2024)
Abstract
One of the most important issues for researchers in the propulsion field is the selection of a suitable stabilizer to maintain the desired mechanical properties and proper propellant One of the most important issues for researchers in the propulsion field is the selection of a suitable stabilizer to maintain the desired mechanical properties and proper propellant performance during storage time. In this research, hardness tests, oxidation induction time and thermogravimetric analysis (TGA) were performed on poly diethylene glycol adipate (PDEGA) elastomer with 0.2 weight percent of three types of stabilizer (2-nitrodiphenylamine (NDPA), N-methyl-4-nitroaniline (MNA) and Centralit I) in the presence of trimethylol trinitrate (TMETN) plasticizer, Triphenyl bismuth catalyst and trimethylolpropane chain extender. The results obtained from the hardness tests showed that the hardness of the PDEGA elastomer including N-methyl-4-nitroaniline stabilizer has decreased by about 68% compared to the elastomer without this stabilizer. Also, oxidation induction time and thermogravimetric analysis showed that the elastomer containing N-methyl-4-nitroaniline stabilizer has more resistance to oxidation and mass reduction than elastomer with another stabilizers and causes a longer storage life.
