Chemomechanical, morphological, and rheological studies of chitosan‐graft‐lactic acid oligomer reinforced poly(lactic acid) bionanocomposite films

• Published in: Journal of applied polymer science 2018-01, Vol.135 (3), p.n/a
• Main Authors: Pal, Akhilesh Kumar, Bhattacharjee, Sayan Kumar, Gaur, Surendra Singh, Pal, Ajinkya, Katiyar, Vimal
• Format: Article
• Language: English
• Subjects: Acids; Biodegradability; biodegradable; Chemical synthesis; Chitosan; Condensation polymerization; Dispersion; Dynamic mechanical analysis; Elongation; Glass transition temperature; Grafting; Loss modulus; Materials science; micelles; NMR; Nuclear magnetic resonance; Polylactic acid; Polymers; Rheological properties; Rheology; Storage modulus
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.45546

ABSTRACT Various compositions of nontoxic biodegradable poly(lactic acid) (PLA)/chitosan‐graft‐lactic acid oligomer (CH‐g‐OLLA) bionanocomposite films were fabricated with a solution casting technique by the dispersal of CH‐g‐OLLA copolymer at different amounts (1, 3, and 5 wt %) into the PLA matrix. The filler (CH‐g‐OLLA) was synthesized by an in situ condensation polymerization reaction in a microwave, and the grafting of lactic acid oligomer chains at the C2 position of the chitosan backbone was confirmed by the presence of new peaks at 179.08 and 174.41 ppm in 13C‐NMR analysis. The transparency results show the synergic effect of CH‐g‐OLLA in the form of reduced transparency and excellent blocking capability of UV light. Dynamic mechanical analysis confirmed a reduction in the glass‐transition temperature (up to ∼13 °C) with increasing filler concentration; this signified the improvement in the elongation of bionanocomposite films. The rheological studies showed the viscous behavior of the PLA and PLA–CH‐g‐OLLA bionanocomposite films as the storage modulus values were found to be lower than the loss modulus values over the entire range of angular frequency at 180 °C. Furthermore, a Cole–Cole plot and Han plot described the uniform dispersion of the filler in the PLA matrix, its agglomeration at higher loading, and the structural change between the PLA and PLA–CH‐g‐OLLA bionanocomposite films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45546.