آمیخته پلی‌(لاکتیک اسید)-اتیلن-co-وینیل استات بسیارچقرمه با افزودن هم‌زمان نانوذرات آب‌گریز و سازگارکننده

نوع مقاله: پژوهشی

نویسندگان

قم، دانشگاه صنعتی قم، دانشکده فنی مهندسی، گروه مهندسی پلیمر، صندوق پستی 1519-37195

10.22063/jipst.2021.1778

چکیده

فرضیه: در سال‌های اخیر، با توجه به موضوع‌های آلودگی زیست‌محیطی، صنایع پلاستیک به مصرف پلاستیک‌های زیست تخریب‌پذیر تشویق شده‌اند. پلی‌(لاکتیک اسید)، PLA، از شناخته‌شده‌ترین پلیمرهای زیست‌تخریب پذیر با برتری ماهیت زیست‌پایه است. عیب اصلی PLA شکنندگی ذاتی آن بوده که آمیخته‌سازی مناسب‌ترین روش برای غلبه بر آن است.
روش‌ها: PLA بسیار چقرمه از کوپلیمر اتیلن-وینیل استات (EVA)، در مجاورت نانوذرات آب‌گریز سیلیکا و سازگارکننده کوپلیمر قطعه‌ای (استیرن-اتیلن-بوتیلن-استیرن) دارای مالئیک انیدرید (SEBS-g-MA) با آمیخته‌سازی مذاب تهیه شد. شکل‌شناسی، خواص گرمایی، خواص مکانیکی و رئولوژی نمونه‌ها بررسی شد.
یافته‌ها: عکس‌های میکروسکوپی الکترون عبوری (TEM) تأیید کرد، نانوذرات سیلیکا به‌طور عمده در قطره‌های EVA و سطح مشترک EVA و PLA و نیز مقداری در ماتریس PLA قرار گرفته‌اند. همچنین، با واردکردن نانوذرات، اندازه متوسط قطره‌های EVA کاهش یافت و استحکام
در سطح مشترک بهبود یافت. با وجود سازگارکننده شکل‌شناسی به‌طور چشمگیری تغییر یافت و فاز پراکنده کروی EVA به‌شکل رشته‌ای درآمد. با افزودن نانوذرات و نیز سازگارکننده مقدار بلورینگی PLA در آمیخته‌ها کاهش یافت. با افزودن phr 5 نانوذرات سیلیکا ازدیاد طول تا پارگی، چقرمگی و استحکام ضربه‌ای به‌طور شایان توجهی افزایش یافت. افزودن هم‌زمان نانوذرات و سازگارکننده به‌طور چشمگیری باعث بهبود خواص مکانیکی شد. به‌عنوان مثال، ازدیاد طول تا پارگی و استحکام ضربه‌ای آمیخته سازگارشده PLA/EVA دارای phr 5 نانوسیلیکا از %7 و 5.1kJ/m2  به‌ترتیب به %141 و 71kJ/m2 (در مقایسه با آمیخته خالص) افزایش یافت. ریزساختار آمیخته‌ها با نتایج رئولوژی خطی ارزیابی شد.

کلیدواژه‌ها


عنوان مقاله [English]

A Highly Toughened Poly(lactic acid)/Ethylene-co-Vinyl Acetate Blend with the Simultaneous Addition of Hydrophobic Nanoparticles and Compatibilizer

نویسندگان [English]

  • Zahra Sadat Hoseini
  • Jafar Khademzadeh Yeganeh
  • Salar Moradi
Department of Polymer Engineering, Faculty of Engineering, Qom University of Technology, P.O. Box: 37195-1519, Qom, Iran
چکیده [English]

Hypothesis: In recent years, due to environmental pollution and sustainability issues, plastic industries have been encouraged to use biodegradable polymers. Poly(lactic acid) (PLA) is one of the most well-known biodegradable polymers with the advantage of bio-based nature. However, the inherent brittleness of PLA is its main disadvantage. The blending technique is the most effective and practical method to overcome the brittleness of PLA.
Methods: A highly toughened PLA was prepared through physical melt-blending with ethylene-vinyl acetate (EVA) in the presence of hydrophobic nanosilica and SEBS-g-MA block copolymer compatibilizer. The morphology, thermal properties, mechanical properties, and linear rheology of the samples were investigated.
Findings: Transmission electron microscopy (TEM) images revealed that nanosilica is predominantly localized in the EVA droplets and at the interface of PLA and EVA. Some were also resided in the PLA matrix. Upon incorporating of nanoparticles, the interfacial strength improved and that the average droplet size was decreased. In the presence of compatibilizer, the morphology considerably changed: the dispersed spherical EVA phase turned into the cylindrical shape. Addition of copolymer and nanoparticles decreased the crystallization of PLA in the blends. Addition of 5 phr nanosilica considerably enhanced tensile toughness, elongation-at-break, and impact strength. On the other hand, the simultaneous addition of nanoparticles and compatibilizer dramatically improved the mechanical properties. For example, the elongation-at-break and impact strength of the compatibilized PLA/EVA blend
containing 5 phr nanosilica were increased from 7% and 5.1 kJ/m2 to 141% and 71 kJ/m2 (compared to a neat blend), respectively. Finally, the microstructure of the blends was assessed through rheological measurements.

کلیدواژه‌ها [English]

  • poly(lactic acid)
  • ethylene-co-vinyl acetate
  • toughening
  • SEBS-g-MA compatibilizer
  • hydrophobic nanosilica
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