Near-infrared (NIR) disrelation mapping analysis for poly(lactic) acid nanocomposite

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 181; pp. 1 - 6
• Main Authors: Shinzawa, Hideyuki, Mizukado, Junji
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.06.2017
• Subjects: Disrelation mapping; Near infrared (NIR) spectroscopy; Poly(lactic) acid (PLA); Two-dimensional (2D) correlation spectroscopy; Disrelation mapping; Near infrared (NIR) spectroscopy; Two-dimensional (2D) correlation spectroscopy; Poly(lactic) acid (PLA)
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2017.03.026

Near infrared (NIR) imaging data of poly(lactic) acid (PLA) nanocomposite were analysed by disrelation mapping to prove the possible interaction between PLA matrix and montmorillonite-based nanoclay. The basic concept of disrelation mapping can be viewed as a spatial filter based on two-dimensional (2D) correlation function to elucidate specific areas where disrelated variation between intensities occurs. Correlation intensity develops on disrelation map only if spectral intensities at v1 and v2 within the local spatial area vary in a dissimilar manner. This feature is especially suitable for identifying the area where interaction between components occurs, which is not fully detected by the conventional visualizations based on a single wavenumber. Disrelation maps constructed with NIR bands arising from the crystalline and amorphous components of the PLA. The pattern appearing on the disrelation map indicated different distributions of the crystalline and amorphous components of the nanocomposite sample. In addition, the development of disrelation intensity becomes acute especially at the area adjacent to the clay, revealing that the clay essentially works as nucleating agent to cause the additional development of crystalline structure of PLA by lowering the surface energy barrier. [Display omitted] •Disrelation mapping was applied to NIR imaging data of PLA-nanocomposite.•Disrelation map improved visibility of NIR image by taking advantages of 2D correlation spectroscopy.•Additional development of PLA crystals was observed at the interface between PLA and nanoclay.