Crystallization and Morphology of Nanocomposites Based on Poly(lactic acid)/Graphene Nanoplatelets: Effect of Nanoparticle Functionalization

Document Type : Research Paper

Authors

1 Polymer Engineering Department, Kashan Branch, Islamic Azad University, P.O. Box: 87135-433, Kashan, Iran

2 Department of Plastics, Faculty of Processing, Iran Polymer and Petrochemical Institute, P.O. Box: 14975-112, Tehran, Iran

3 Department of Applied Chemistry, Islamic Azad University, South Tehran Branch, P.O. Box: 17776-13651, Tehran, Iran

Abstract

Crystallization behavior of nanocomposite based on semicrystalline polymers and graphene nanoplatelets (GNp) has been considered due to its critical effect on the performance of the final product. In this study, nanocomposite based on poly(lactic acid)/graphene nanoplatelets (PLA/GNp, 0.5 and 1 wt %) was prepared via solution method using dimethylformamide as a solvent. PLA has the largest contribution in the current biopolymer research. To present time, it is well accepted that nanoparticles would be recognized as efficient heterogeneous nucleating agents for various semicrystalline polymers. To improve the dispersion of graphene in the matrix, functionalization using acid treatment and acylation reaction was accomplished. Characterization of functionalization reaction and grafting reaction between PLA and functionalized graphene (FGNp) was tracked by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetry analysis. Scanning electron microscopy results demonstrated that a relatively fine dispersion of FGNp is achieved in the PLLA matrix. Non-isothermal and isothermal crystallization behavior was studied using differential scanning calorimetry. The isothermal tests were conducted at test temperatures 130°C, 125°C, 120°C and 115°C. The results indicated that crystallization percentage for the samples containing FGNp nanoparticles were higher than those of pristine-containing samples. With increase of temperature in isothermal test onset time for crystallization decreased due to higher mobility of polymeric chains in the samples. It seems that the presence of functionalized nanoparticles facilitated formation of β format of crystals.

Keywords

Iranian Journal of Polymer Science and Technology
Volume 27, Issue 5 - Serial Number 5
November and December 2014
Pages 394-383

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