Crystallization of triethyl‐citrate‐plasticized poly(lactic acid) induced by chitin nanocrystals

• Published in: Journal of applied polymer science 2019-09, Vol.136 (36), p.n/a
• Main Authors: Singh, Shikha, Maspoch, Maria Lluisa, Oksman, Kristiina
• Format: Article
• Language: English
• Subjects: Chitin; Chitin nanocrystals; Cooling rate; Cristal·lització; Crystallization; Degree of crystallinity; Enginyeria dels materials; Isothermal crystallization; Materials plàstics i polímers; Materials science; Microscopy; Microstructure; Nanocristalls; Nanocrystals; Nucleation; Optical microscopy; Plasticizer; poly(lactic acid); Polylactic acid; Polymers; Scanning electron microscopy; Spherulites; Trä och bionanokompositer; Wood and Bionanocomposites; X-ray diffraction; Àrees temàtiques de la UPC
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.47936

ABSTRACT The aim of this study was to gain a better understanding of the crystallization behavior of triethyl‐citrate‐plasticized poly(lactic acid) (PLA–TEC) in the presence of chitin nanocrystals (ChNCs). The isothermal crystallization behavior of PLA–TEC was studied by polarized optical microscopy, scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction (XRD). Interestingly, the addition of just 1 wt % ChNCs in PLA–TEC increased the crystallization rate in the temperature range of 135–125 °C. The microscopy studies confirmed the presence of at least three distinct types of spherulites: negative, neutral, and ring banded. The ChNCs also increased the degree of crystallinity up to 32%, even at a fast cooling rate of 25 °C min−1. The XRD studies further revealed the nucleation effect induced by the addition of ChNCs and thus explained the faster crystallization rate. To conclude, the addition of a small amount (1 wt %) of ChNC to plasticized PLA significantly affected its nucleation, crystal size, and crystallization speed; therefore, the proposed route can be considered suitable for improving the crystallization behavior of PLA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47936. Polarized optical microscopy image of isothermal crystallization of triethyl‐citrate‐plasticized poly(lactic acid) (PLA–TEC) in the presence of PLA–TEC–chitin nanocrystal (ChNC) showing the increased crystallization of PLA–TEC with ChNC.