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Journal of Spectroscopy
Volume 2015, Article ID 902340, 8 pages
Research Article

A Simple Approach to Distinguish Classic and Formaldehyde-Free Tannin Based Rigid Foams by ATR FT-IR

1Forest Products Technology & Timber Construction Department, Salzburg University of Applied Sciences, 136a Marktstraße, 5431 Kuchl, Austria
2School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 Penang, Malaysia

Received 9 October 2014; Accepted 9 February 2015

Academic Editor: Eugen Culea

Copyright © 2015 Gianluca Tondi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Tannin based rigid foams (TBRFs) have been produced with formaldehyde since 1994. Only recently several methods have been developed in order to produce these foams without using formaldehyde. TBRFs with and without formaldehyde are visually indistinguishable; therefore a method for determining the differences between these foams had to be found. The attenuated total reflectance infrared spectroscopy (ATR FT-IR) investigation of the TBRFs presented in this paper allowed discrimination between the formaldehyde-containing (classic) and formaldehyde-free TBRFs. The spectra of the formaldehyde-free TBRFs, indeed, present decreased band intensity related to the C–O stretching vibration of (i) the methylol groups and (ii) the furanic rings. This evidence served to prove the chemical difference between the two TBRFs and explained the slightly higher mechanical properties measured for the classic TBRFs.