خواص مکانیکی و حافظه‌شکلی آمیخته‌های پلی‌(وینیل استات)-پلی(لاکتیک اسید)

نوع مقاله: پژوهشی

نویسندگان

1 مراغه، دانشگاه مراغه،گروه مهندسی شیمی، صندوق پستی 83111-55181

2 تهران، پژوهشگاه پلیمر و پتروشیمی ایران، گروه پلاستیک، صندوق پستی 112-14975

چکیده

مواد حافظه شکلی، موادی هستند که قابلیت تغییرشکل از شکل موقت به اصلی را تحت محرک‌های مناسب دارند. هدف از این کار، تهیه مواد حافظه شکلی برپایه مواد پلیمری با استفاده از روش آسان، مقرون به‌صرفه و بدون نیاز به ‌روش‌های سنتزی پیچیده است. بنابراین، مواد حافظه شکلی با آمیخته‌سازی دو زیست‌پلیمر PVAc و PLA با روش اختلاط محلول تهیه شد و ریزساختار آن‌ها به‌کمک آزمون‌های XRD و AFM بررسی شد. همچنین، خواص مکانیکی و گرمایی آمیخته‌های تهیه شده با آزمون‌های کشش، DSC و DMTA ارزیابی شد. مشاهده میکروسکوپی نشان داد، دو جزء از آمیخته به‌طور یکنواخت در یکدیگر پراکنده شدند  و آمیخته‌ای تک‌فاز تشکیل دادند. همچنین، امتزاج‌پذیری اجزای آمیخته با آزمون‌های گرمایی تأیید شد. افزون بر این، نتایج آزمون‌های کشش و DMTA نشان داد، آمیخته‌سازی PVAc با PLA، به افزایش مدول و استحکام PVAc منجر می‌شود. در نهایت، نتایج بررسی‌های‌ رفتار حافظه شکلی نمونه‌ها نشان داد، آمیخته PVAc/PLA دارای %30 وزنی PLA خاصیت حافظه شکلی بهتری نسبت به پلیمرهای خالص دارد. به‌عنوان مثال، با افزودن %30 وزنی PLA به PVAc، مقدار بازگشت شکلی از %75.4 به %91.5 افزایش یافت. بهبود شایان توجه در مقدار و سرعت بازیابی شکلی، به بیشتربودن انرژی کشسانی ذخیره شده در آمیخته‌ها نسبت داده شد که نیروی محرکه زیادی برای بازیابی شکلی سریع‌تر و کامل‌تر فراهم می‌کند. آمیخته حافظه شکلی تهیه شده در این کار، با داشتن مزایایی نظیر استفاده از زیست‌پلیمرهای تجاری به‌عنوان مواد پایه، سهولت تهیه و خواص حافظه شکلی خوب، می‌تواند در کاربردهای زیست‌پزشکی مورد توجه قرار گیرد.


کلیدواژه‌ها


عنوان مقاله [English]

Mechanical and Shape Memory Properties of Poly(vinyl acetate)/Poly(lactic acid) Blends

نویسندگان [English]

  • Masoud Babaahmadi 1
  • Mohammad Sabzi 1
  • Ismaeil Ghasemi 2
1 Department of Chemical Engineering, Faculty of Engineering, University of Maragheh, P.O.Box: 55181-83111, Maragheh, Iran
2 Department of Plastics, Iran Polymer and Petrochemical Institute (IPPI), Tehran P.O.Box: 14975-112, Iran
چکیده [English]

Hypothesis: Shape memory polymers (SMPs) are intelligent materials that can be set into temporary shape and return to their permanent (original) shape when an external stimulus is applied. Poly(vinyl acetate) (PVAc) is a low cost biopolymer. However, its use in biomedical applications, especially as an SMP, is limited due to its low modulus and strength. On the other hand, poly(lactic acid) (PLA) is a biodegradable polymer with robust structure. Hence, blending of these two polymers can improve mechanical properties as well as shape memory behavior of PVAc.
Methods: a series of shape memory materials were prepared through blending of PVAc and PLA through solution mixing method using chloroform as solvent.
Findings: Microstructure of the prepared samples studied by X-ray diffraction spectroscopy (XRD) and atomic force microscopy (AFM), indicated that the components of the blends were favorably compatible. Moreover, dynamic mechanical thermal analysis (DMTA) and tensile test showed that the blending of these compatible biopolymers led to improvement in tensile strength and modulus of PVAc. Finally, the shape memory experiments revealed that the PVAc/PLA blends exhibited improved shape memory behavior as compared with their parent polymers. For instance, by incorporation of 30 wt% PLA into PVAc, the shape recovery increased from 75.4 to 91.5%. The improvement in the shape recovery was assigned to higher stored elastic energy in the blends as compared with that in neat polymers, which provided a larger driving force for corresponding quick and almost complete shape recovery. This procedure may open an avenue to fabricate SMPs through a simple blending method to be applied in different biomedical areas.

کلیدواژه‌ها [English]

  • poly(lactic acid)
  • poly(vinyl acetate)
  • blending
  • mechanical properties
  • shape memory polymer

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