نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد، مهندسی شیمی، دانشگاه تهران، تهران.

2 دانشجوی کارشناسی، مهندسی پلیمر، دانشگاه تهران، تهران.

3 استادیار، مهندسی پلیمر، دانشگاه تهران، تهران.

4 دانشیار، شیمی آلی، دانشگاه تهران، تهران.

10.22068/jstc.2020.112497.1576

چکیده

در این پژوهش، خواص ساختاری و مکانیکی فوم های میکروسلولی نانوکامپوزیتی پلی اتیلن (PE)/کوپلیمر اتیلن-وینیل استات (EVA)/نانورس تهیه شده طی فرآیند فوم سازی اکستروژنی به روش فیزیکی با بکارگیری گاز دی اکسیدکربن در برابر غلظت PE/EVA، درصد بارگذاری نانورس اصلاح شده و پروفایل دمایی اکسترودر مورد بررسی قرار گرفته است. فرایند فوم سازی این سامانه ها به دلیل دو انتقال فازی همزمان شامل رفتار فازی دمای انحلال بحرانی فوقانی (UCST) آمیخته های PE/EVA وانتقال فاز گاز در فرایند هسته گذاری و رشد حباب ها بعد از خروج از دای فیلم تخت از پیچیدگی های بالایی برخوردار است. به دلیل رفتار فازی UCST آمیخته PE/EVA، افزایش دمای فرایندی بر روی مورفولوژی و خواص مکانیکی فوم ها بدست آمده تاثیر به سزایی داشته و افزایش دما منجر به امتزاج پذیری بهتر دو پلیمر در آمیخته ها و نانوکامپوزیت ها گردیده است. علاوه بر این، نانورس با اثر سازگارسازی خود موجب بهبود امتزاج پذیری دو فاز پلیمری می شود. با افزایش دمای فرایندی در تهیه فوم ها دیده شده است که در دمای بالاتر فوم هایی سبک تر با تراکم سلولی بیشتر بدست می آید. افزایش محتوای EVA در آمیخته موجب بهبود پراکنش نانوذرات و متعاقباً بهبود ساختار فوم ها می شود. با افزایش دما به دلیل بهبود امتزاج پذیری دو فاز و افزودن نانوذرات به دلیل نقش موثرشان در ایجاد حباب ها، به ترتیب مدول فوم ها افزایش و کاهش یافته است.

کلیدواژه‌ها

عنوان مقاله [English]

Polyethylene/ethylene-vinyl acetate copolymer/nanoclay nanocomposite foams with two concurrent phase transitions in continuous extrusion process: Effects of material and processing parameters

نویسندگان [English]

  • Reza Ghasemi 1
  • Reza Kazemi 2
  • Farkhondeh Hemmati 3
  • Jamshid Mohammadi-Rovshandeh 4

1 Caspian Faculty of Engineering, College of Engineering, University of Tehran, Rezvanshar, Iran.

2 Caspian Faculty of Engineering, College of Engineering, University of Tehran, Rezvanshar, Iran.

3 Caspian Faculty of Engineering, College of Engineering, University of Tehran, Rezvanshar, Iran.

4 Caspian Faculty of Engineering, College of Engineering, University of Tehran, Rezvanshar, Iran.

چکیده [English]

In this research, the structure and mechanical properties of polyethylene (PE)/ethylene-vinyl acetate copolymer (EVA)/nanoclay microcellular foams obtained through extrusion physical foaming by using carbon dioxide were investigated. The effect of PE/EVA concentration, organically-modified nanoclay and temperature profile on the properties were evaluated. The foaming process of these systems has significant complexity due to the occurrence of two concurrent phase transitions including upper critical solution temperature (UCST) phase behavior of PE/EVA blends and gas phase transition in the cell nucleation and growth process. Owing to the UCST phase behavior of PE/EVA mixtures, an increment in the process temperature profile has a profound impact on the morphology and mechanical properties of the foams and results in higher miscibility of the polymeric constituents of the blends and nanocomposites. Moreover, the nanoclay compatibilization mechanism leads to better miscibility of the polymeric phases. At higher temperature profile, lighter foams with higher cell density are obtained. Increasing the EVA content in the blends improves the nanoclay dispersion state and as a result, causes an improvement in the foam structure. By increasing the temperature profile and adding nanoclay, the elastic modulus of the foams improves and worsens respectively, due to the better PE/EVA miscibility state and nanoparticle influential role in the bubble formation.

کلیدواژه‌ها [English]

  • extrusion
  • Nanocomposite
  • Foam
  • Polymer

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