بهینه‌سازی عامل‌های مؤثر بر تهیه کوپلیمر سه‌قطعه‌ای پلی‌پروپیلن گلیکول-پلی‌گلیسیدیل نیترات-پلی‌پروپیلن گلیکول و بررسی خواص گرمایی آن

نوع مقاله: پژوهشی

نویسندگان

1 تهران، دانشگاه صنعتی مالک اشتر، دانشکده شیمی و مهندسی شیمی، صندوق پستی 3454-16765

2 قزوین ، دانشگاه بین‌المللی امام خمینی (ره)، دانشکده شیمی، صندوق پستی 16818-34149

10.22063/jipst.2020.1721

چکیده

فرضیه: پلی‌گلیسیدیل نیترات (PGN) به‌دلیل داشتن خواصی همچون انرژی تشکیل مناسب، چگالی، توازن اکسیژن و آنتالپی انفجار زیاد و سازگاری مناسب با سایر اجزا، در تهیه الاستومر‌های پیشرانه به‌کار گرفته می‌شود. این پلیمر افزون بر خواص مطلوب عیب‌هایی از جمله دمای انتقال شیشه‌ای زیاد، خواص مکانیکی ضعیف و مقدار جامد کل کم دارد. همچنین، الاستومر آن می‌تواند متحمل واپخت شود. برای رفع این عیب‌ها، کوپلیمرهایی از آن‌ با پلیمرهایی با خواص گرمایی و مکانیکی مطلوب تهیه می‌شود.
روش‌ها: در این پژوهش، برای اولین بار کوپلیمر سه‌قطعه‌ای پرانرژی پلی‌پروپیلن گلیکول-پلی‌گلیسیدیل نیترات-پلی‌پروپیلن گلیکول، PPG-PGN-PPG، با روش پلیمرشدن حلقه‌گشای کاتیونی پروپیلن اکسید، در مجاورت پلی‌گلیسیدیل نیترات به‌عنوان درشت‌آغازگر و بور تری‌فلوئورید اترات (BF3.OEt2) به‌عنوان کاتالیزگر تهیه شد. اثر دما و مقدار کاتالیزگر بر وزن مولکولی و بازده واکنش بررسی شد. محصول به‌دست‌آمده با روش‌های سوانگاری ژل تراوا (GPC)، ‌رزونانس مغناطیسی هسته هیدروژن (1H NMR) و کربن (13C NMR) و طیف‌سنجی زیرقرمز تبدیل فوریه (FTIR) شناسایی شد. همچنین خواص گرمایی کوپلیمر‌ با آزمون‌های گرماوزن‌سنجی (TGA) و گرماسنجی پویشی تفاضلی (DSC) مطالعه شد.
یافته‌ها: نتایج نشان داد، با افزایش دما از 0 به 15 درجه سلسیوس، درصد تبدیل و بازده افزایش یافت. از سوی دیگر، با توجه به دمای جوش کم پروپیلن اکسید (34 درجه سلسیوس،) و گرمازابودن واکنش، افزایش دمای واکنش به بیش از 15 درجه سلسیوس امکان‌پذیر نیست. همچنین با افزایش مقدار کاتالیزگر از %0.2 به %1 وزنی نسبت به آغازگر، وزن مولکولی پلیمر افزایش یافت و بیشترین بازده در %1 وزنی کاتالیزگر به‌دست آمد. اما، با افزایش مقدار کاتالیزگر از %1 به %1.5 وزنی، بازده و وزن مولکولی به‌دلیل پیشرفت واکنش‌های جانبی کاهش یافت. مطالعات  TGA و DSC افزایش پایداری گرمایی و کاهش دمای انتقال شیشه‌ای کوپلیمر تهیه‌شده را در مقایسه با PGN نشان داد.

کلیدواژه‌ها


عنوان مقاله [English]

Optimization of Factors Affecting the Synthesis of Polypropylene Glycol/Polyglycidyl Nitrate/ Polypropylene Glycol Triblock Copolymer and Evaluation of Its Thermal Properties

نویسندگان [English]

  • Tayebe Khanlari 1
  • Yadollah Bayat 1
  • Mohammad Bayat 2
1 Department of Chemistry and Chemical Engineering, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran, Iran
2 Department of Chemistry, Imam Khomeini International University, P.O. Box 34149-16818, Qazvin, Iran
چکیده [English]

Hypothesis: 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.
Methods: 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).
Finding: 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.

کلیدواژه‌ها [English]

  • poly glycidyl nitrate
  • propellant
  • triblock copolymer
  • propylene oxide
  • thermal properties
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