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A Near‐Infrared Spectroscopy Study on Thermal Transitions of PMMA and PMMA/SiO 2 Nanocomposites
Author(s) -
Sanchez Freddy A.,
Redondo Marta,
Olmos Dania,
Kuzmanovic Maja,
GonzálezBenito Javier
Publication year - 2014
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201300137
Subject(s) - absorbance , materials science , glass transition , infrared spectroscopy , polymer , nanocomposite , infrared , spectroscopy , analytical chemistry (journal) , nanoparticle , polymer nanocomposite , polymer chemistry , composite material , optics , nanotechnology , chemistry , organic chemistry , physics , quantum mechanics
Summary In this work infrared spectroscopy in the near infrared (NIR) range is used to study the dynamics of polymethylmethacrylate (PMMA) as a pure polymer and when it is modified with silica nanoparticles. Different ways of analyzing FT‐NIR spectra were explored taking the temperature as the variable of the systems: i) bands shifts in terms of the first moment of the wavenumber; ii) bands shifts in terms of an absorbance ratio method and iii) absorbance variations in terms of the integrated absorbance. The spectroscopic analysis allowed to study thermal transitions in PMMA and PMMA based nanocomposites. In particular the method based on the use of an absorbance ratio is the most sensible to analyze the thermal transitions. All bands considered could be used to detect thermal transitions reflecting how the vibrations of the groups CH 2 ; CH 3 and CO are affected by changes in the free volume of the PMMA. It seems that the PMMA dynamics is more driven by the lateral groups than the backbone of the polymer. The presence of silica nanoparticles, at least when 1% by weight is used, restrains the PMMA motion increasing the relaxation temperatures that can be associated with the glass transitions.