Magnetic Cellulose Nanocrystal Based Anisotropic Polylactic Acid Nanocomposite Films: Influence on Electrical, Magnetic, Thermal, and Mechanical Properties

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• 作者：Prodyut Dhar ; Amit Kumar ; Vimal Katiyar
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：July 20, 2016
• 年：2016
• 卷：8
• 期：28
• 页码：18393-18409
• 全文大小：977K
• 年卷期：0
• ISSN：1944-8252

文摘

This paper reports a single-step co-precipitation method for the fabrication of magnetic cellulose nanocrystals (MGCNCs) with high iron oxide nanoparticle content (∼51 wt % loading) adsorbed onto cellulose nanocrystals (CNCs). X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopic studies confirmed that the hydroxyl groups on the surface of CNCs (derived from the bamboo pulp) acted as anchor points for the adsorption of Fe₃O₄ nanoparticles. The fabricated MGCNCs have a high magnetic moment, which is utilized to orient the magnetoresponsive nanofillers in parallel or perpendicular orientations inside the polylactic acid (PLA) matrix. Magnetic-field-assisted directional alignment of MGCNCs led to the incorporation of anisotropic mechanical, thermal, and electrical properties in the fabricated PLA–MGCNC nanocomposites. Thermomechanical studies showed significant improvement in the elastic modulus and glass-transition temperature for the magnetically oriented samples. Differential scanning calorimetry (DSC) and XRD studies confirmed that the alignment of MGCNCs led to the improvement in the percentage crystallinity and, with the absence of the cold-crystallization phenomenon, finds a potential application in polymer processing in the presence of magnetic field. The tensile strength and percentage elongation for the parallel-oriented samples improved by ∼70 and 240%, respectively, and for perpendicular-oriented samples, by ∼58 and 172%, respectively, in comparison to the unoriented samples. Furthermore, its anisotropically induced electrical and magnetic properties are desirable for fabricating self-biased electronics products. We also demonstrate that the fabricated anisotropic PLA–MGCNC nanocomposites could be laminated into films with the incorporation of directionally tunable mechanical properties. Therefore, the current study provides a novel noninvasive approach of orienting nontoxic bioderived CNCs in the presence of low magnetic fields, with potential applications in the manufacturing of three-dimensional composites with microstructural features comparable to biological materials for high-performance engineering applications.