عامل‌های مؤثر بر سینتیک واکنش و اندازه ذره در پلیمرشدن تعلیقی استیرن در مجاورت گرافیت

نوع مقاله : پژوهشی

نویسندگان

1 تبریز، دانشگاه صنعتی سهند، پژوهشکده مواد پلیمری، کد پستی 5331817634

2 تبریز، مجتمع پتروشیمی تبریز، واحد طرح و توسعه، کد پستی 5197133377

چکیده

فرضیه: پلیمرشدن تعلیقی استیرن در مجاورت ذرات گرافیت انجام شد. برای درک بهتر فرایند و تنظیم عامل‌های آن، سینتیک گرمایی واکنش پلیمرشدن بررسی شد. اثر عامل‌های مختلف فرایند بر توزیع اندازه دانه ‏ها ارزیابی و مقدار رسانندگی گرمایی اسفنج‌های حاصل مطالعه شد.
روش‌ها: شناسایی محصول و سینتیک گرمایی واکنش پلیمرشدن با آزمون‌های گرماسنجی تفاضلی پویشی (DSC)، گرماوزن‌سنجی (TGA) و اندازه‌گیری توزیع اندازه ذره و رسانندگی گرمایی ارزیابی شد. اثر علظت گرافیت و آغازگر بر سینتیک واکنش بررسی شد.
یافته‌ها: نتایج نشان داد، با وجود ذرات گرافیت سرعت واکنش پلیمرشدن رادیکال آزاد به‌شدت کم شده و این موضوع موجب ناپایداری سامانه تعلیق و مانع از تولید محصول مناسب می‌شود. با تنظیم متغیر‌های فرایند مانند افزایش مقدار پایدارکننده‌ها (1 تا %2) و آغازگر (تا %0.6 وزنی)، دفعات و زمان تزریق آن‌ها، پلیمرشدن ‌استیرن در مجاورت گرافیت انجام شد. دانه‏‌ها کاملاً کروی و بسیار ریز (کمتر از 420µm) کمتر از %5 نسبت به محصول بودند. دانه‏‌های انبساط‌یافته طی فرایند پیش‌انبساط ساختار سلولی یکنواختی داشتند. مقدار پنتان باقی‌مانده درون دانه‏‌های پیش‌انبساط‌یافته به اندازه کافی (حدود %7 وزنی) بود تا در مرحله انبساط نهایی، قالب‌های اسفنج دارای جوش‌خوردگی مناسبی باشند. اسفنج‌های نهایی دارای 0، 1 و %1.5 گرافیت بودند. مقدار رسانندگی گرمایی اسفنج‌های دارای گرافیت با افزایش مقدار گرافیت کاهش یافت. در نتیجه، اسفنج‌های دارای گرافیت در مقایسه با پلی‌استیرن انبساط‌یافته معمولی، عایق‌های گرمایی بهتری بودند. بنابراین برای کار ویژه گرمایی، به مقدار کمتری از پلی‌استیرن انبساط‌یافته دارای گرافیت نسبت به پلی‌استیرن معمولی نیاز است، در نتیجه هزینه کل عایق کاهش می‌یابد.

کلیدواژه‌ها

عنوان مقاله [English]

Effective Parameters on Reaction Kinetics and Particle Size in the Suspension Polymerization of Styrene in the Presence of Graphite

نویسندگان [English]

  • Morteza Nasiri 1
  • Farhang Abbasi 1
  • Naser Harasi 2
1 Institute of Polymeric Materials, Sahand University of Technology, Postal Code 5331817634, Tabriz, Iran
2 Research and Development Center, Tabriz Petrochemical Complex , Postal Code 5197133377, Tabriz, Iran
چکیده [English]

Hypothesis: suspension polymerization of styrene in the presence of graphite was carried out. The polymerization reaction kinetics was investigated to gain better insight into manipulating process parameters. The particle size distribution and thermal conductivity of the foams were studied by considering different parameters.
Methods: Product characterization and the reaction thermal kinetics were evaluated using differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), particle size distribution and thermal conductivity measurements. The effect of graphite and initiator concentration on the reaction kinetics was investigated.
Findings: The results showed that the graphite profoundly reduced the rate of reaction and consequently caused instability in the suspension. By manipulating the process variables such as increasing the amount of stabilizers (1 to 2%) and initiator (up to 0.6% by wt), their frequency and injection time, the polymerization of styrene in the presence of graphite was done. The beads were spherical and the superfine (less than 420 μm) proportion of the product was less than 5%. Through the pre-expansion process, the beads were expanded and the cell structure was uniform. The pentane content of the beads was sufficient (~7% by wt) to successfully sinter the pre-expanded beads in the final molding process. Final foams had 0, 1 and 1.5% graphite. By increasing the graphite content, the thermal conductivity of the foams was decreased. Graphite-containing foams were better thermal insulators than conventional expandable polystyrene. Therefore, for a specific thermal duty, a smaller amount of graphite-containing expandable polystyrene rather than conventional polystyrene is required and consequently, the total cost of the insulation is reduced.

کلیدواژه‌ها [English]

  • expandable polystyrene
  • graphite
  • thermal insulation
  • in-situ polymerization
  • reaction kinetics

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مجله علوم و تکنولوژی پلیمر
دوره 33، شماره 2 - شماره پیاپی 166
خرداد و تیر 1399
صفحه 137-146

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