نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری

2 استاد گروه علوم و مهندسی صنایع غذایی دانشگاه تهران

3 دانشیار پژوهشگاه پلیمر و پتروشیمی ایران

چکیده

هدف مطالعه حاضر توسعه نانوکامپوزیت‌های جدید بهبود یافته بر پایه بیوپلیمر پلی­لاکتیک­اسید (PLA) است.  برای رسیدن به این هدف، نانو کامپوزیت‌های PLAبا استفاده از نانوذرات رسی و سلولزی در سطوح مختلف با روش کستینگ تهیه شدند و خواص حرارتی، نفوذپذیری نسبت به بخار آب (WVP) و ساختار آن­ها ارزیابی شد.  نتایج آزمون حرارتی (DSC) نشان می‌دهد که نقطه انتقال شیشه‌ای (Tg)، نقطه ذوب (Tm) و درصد کریستالیزاسیون (χ%)PLA خالص، به ترتیب 83/53، 95/153 درجة سلسیوس و 36/41 درصد است.  در اثر الحاق نانوذرات رس، نقطه انتقال شیشه‌ای و درصد کریستالیزاسیون روند صعودی دارند در حالی­که نقطه ذوب تغییر محسوسی نشان نمی‌دهد.  نانو ذره سلولز میکروکریستال به ­دلیل ناسازگار بودن با بستر پلیمری تأثیری بر خواص حرارتی ندارد.  نفوذپذیری نسبت به بخار آب در PLAخالص بالاست که با افزودن نانوذرات رس به آن، به شدت کاهش می‌یابد به طوری­که در نمونه حاوی 7 درصد به مقدار 11-10X 92/0 رسیده است.  سلولز میکروکریستال (MCC) به دلیل ماهیت آب­ دوست بودن، منجر به افزایش چشمگیر نفوذپذیری به بخار آب فیلم‌ها گردید.  تصاویر SEMتهیه شده از نمونه‌ها نیز نتایج قبلی را تأیید می‌کنند. 

عنوان مقاله [English]

Thermal Properties, Water Vapor Permeability and Morphology of Polylactic Acid Bionanocomposites

چکیده [English]

The present study developed an improved nanocomposite based on polylactic acid (PLA) biopolymer. The structural properties of PLA nanocomposites of clay and cellulose nanoparticles were evaluated for level and water vapor permeability (WVP) using thermal and casting methods. Thermal tests (DSC) showed that pure PLA had a glass transition point (Tg) of 53.83, a melting point (Tm) of 153.95°C and crystallization (x%) of 41.36%. With the incorporation of clay nanoparticles, Tg and x% increased, while Tm showed no significant change. The micro-crystal cellulose (MCC) nanoparticles were not compatible with the polymer matrix, so there was no effect on the thermal properties. WVP results showed that pure PLA had high permeability; the addition of clay nanoparticles strongly decreased WVP. The sample with 7% clay had a permeability of 0.92×10-11 g/m.S.Pa. WVP of the film increased significantly as a result of the hydrophilic nature of the MCC. The SEM images of the samples confirmed the results.

کلیدواژه‌ها [English]

  • Nanoparticle
  • Permeability
  • polylactic acid
  • SEM
  • Thermal properties
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