Two-Dimensional Near-Infrared Correlation Spectroscopy Studies on Composition-Dependent Spectral Variations in Ethylene/Vinyl Acetate Copolymers: Assignments of Bands Due to Ethylene Units in Amorphous, Disordered, and Orthorhombic Crystalline Phases
Abstract:Generalized two-dimensional (2D) correlation spectroscopy has been applied to the study of the composition-dependent near-infrared (NIR) spectral changes in 11 different ethylene/vinyl acetate (EVA) copolymers with vinyl acetate (VA) content from 6 to 42 wt%. The 2D synchronous correlation analysis of the 11 NIR spectra has separated the bands due to ethylene units from those due to the VA units. The obtained results are consistent with those reached by the calculation of the second derivative and by chemometrics analysis reported in our previous paper. However, the 2D correlation analysis has given clearer evidence for the band separation. Two-dimensional asynchronous correlation analysis has revealed out-of-phase variations between some bands due to ethylene and some bands due to VA and has determined the order of intensity change between them. On the basis of the order of intensity change, the bands of ethylene in the orthorhombic crystalline phase have been discriminated from those in the amorphous and disordered phases. This paper discusses the potentials of three powerful techniques, 2D correlation analysis, the calculation of the second derivatives, and that of regression coefficients in chemometrics, in unraveling rather complicated NIR spectra.
Document Type: Research Article
Publication date: August 1, 1999
More about this publication?
- The Society publishes the internationally recognized, peer reviewed journal, Applied Spectroscopy, which is available both in print and online. Subscriptions are included with membership or can be purchased by institutional or corporate organizations. Abstracts may be viewed free of charge. Previously published as Bulletin (Society for Applied Spectroscopy)
- Editorial Board
- Information for Authors
- Submit a Paper
- Subscribe to this Title
- Membership Information
- Request copyrighted SAS materials
- Spectroscopic Nomenclature
- Focal Point (Open Access)
- ingentaconnect is not responsible for the content or availability of external websites