نوع مقاله: مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد، مهندسی شیمی، دانشگاه صنعتی سهند، تبریز ، ایران

2 استاد، مهندسی پلیمر، دانشگاه صنعتی سهند، تبریز، ایران

3 دکتری تخصصی، مهندسی شیمی، دانشگاه صنعتی سهند، تبریز، ایران

چکیده

در این تحقیق دینامیک فوم شدن و ریزساختار سلولی پلی‌استایرن و نانوکامپوزیتهای پلی‌استایرن/ نانوسیلیکا حاوی عامل فوم‌زای نرمال پنتان مورد ارزیابی قرار گرفت. برای بررسی دقیق نحوه ایجاد و رشد حباب‌ها در نمونه‌ها از مشاهدات مستقیم تصویربرداری میکروسکوپی درجا استفاده شده و فرآیند فوم‌شدن آن‌ها در سیستم ناپیوسته بررسی گردید. نانوکامپوزیت‌ها به روش اختلاط محلولی تهیه گردیدند و رفتار رئولوژیکی آنها توسط آزمون رئومتری ارزیابی شدند. برای تعیین کشش سطحی نمونه‌ها از آزمون زاویه تماس استفاده گردید. حضور نانوذرات سیلیکا منجر به کاهش زاویه تماس و افزایش کشش سطحی نمونه ها گردید. برای بررسی دینامیک فوم شدن نمونه‌ها، فیلم‌هایی به ضخامت 200 میکرومتر درون محفظه دما و فشار بالا با نرمال پنتان اشباع گردیدند و مقدار عامل فوم‌زای یکسانی در همه نمونه ها وارد شد. دینامیک فوم‌شدن توسط سامانه طراحی شده مورد مطالعه قرار گرفت. اثر دما بر روی دینامیک فوم‌شدن نمونه‌ها که همگی حاوی %3 وزنی نرمال‌پنتان بودند، بررسی گردید. با وجود این که نرخ هسته‌گذاری و رشد حباب در نمونه‌ها با افزایش دما از ºC140 به ºC160، تقریباً دو برابر گردید، اما توزیع اندازه‌ی سلولی پهن‌تری مشاهده شد. در نمونه‌های نانوکامپوزیتی، هسته‌گذاری نسبت به پلی‌استایرن افزایش یافته و زمان شروع هسته‌گذاری کاهش یافته است. با افزایش مقدار گاز نرمال پنتان در نمونه‌ها به %5 وزنی، میزان هسته‌گذاری در نمونه‌های نانوکامپوزیتی مختلف نسبت به پلی‌استایرن افزایش چشمگیری یافت. برای بررسی ریزساختار نهایی نمونه‌ها، تصاویر SEM تهیه شد و نتایج نشان داد که نانوذرات سیلیکا، ریزساختار نهایی سلول‌ها را یکنواخت‌تر کرده است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental Investigation on the Foaming Dynamics and Cell Microstructure of Polystyrene/Nanosilica/n-Pentane Nanocomposites

نویسندگان [English]

  • Mehdi Zarei 1
  • Mostafa Rezaei 2
  • Mostafa Salehi 3

1 Institute of Polymeric Materials, Department of Polymer Engineering, Sahand University of Technology, Tabriz, Iran

2 Institute of Polymeric Materials, Department of Polymer Engineering, Sahand University of Technology, Tabriz, Iran

3 Institute of Polymeric Materials, Department of Polymer Engineering, Sahand University of Technology, Tabriz, Iran

چکیده [English]

In this study the foaming dynamics and cell microstructure of polystyrene (PS) and polystyrene/nanosilica nanocomposites containing n-pentane foaming agent were investigated. In order to evaluate the nucleation and growth of bubbles in samples, in-situ microscopic observation method was used, and their foaming process in a discontinuous system was investigated. Nanocomposites were prepared by solution mixing method and their rheological properties were determined by rheological test. The contact angle method was used surface tension measurements. Incorporating of nanosilica into PS matrix decreased the contact angle and increased the surface tension of the samples. In order to investigate the foaming dynamics of samples, sheets with thickness of 200 µm were saturated in a high temperature and pressure chamber. Foaming dynamics was studied by the designed system. The temperature effect on the foaming dynamics was investigated in the samples containing of 3 %wt. n-pentane. Although the nucleation and growth rate of bubbles with temperature increasing from 140 to 160 ºC has almost been doubled, but broader cell size distribution was observed. In nanocomposite samples the nucleation has been increased compared to polystyrene, and the onset of nucleation has been dropped. By increasing n-pentane content to 5 %wt., the nucleation in nanocomposite samples was significantly increased compared to polystyrene. For further investigation of the final microstructure of foams, scanning electron microscopy (SEM) images were prepared and the results showed that silica nanoparticles have generated more uniform cells in the final microstructure.

کلیدواژه‌ها [English]

  • Foaming dynamics
  • Polystyrene/nanosilica nanocomposites
  • n-Pentane
  • Cell density
  • Bubble growth

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