Journal of Chromatography A, 1368 (2014) 199–203 Contents lists available at ScienceDirect Journal of Chromatography A j o ur na l ho me page: www.elsevier.com/locate/chroma Application of inverse gas chromatography in physicochemical characterization of phenolic resin adhesives Beata Strzemiecka, Adam Voelkel ∗ , Mateusz Hinz, Mateusz Rogozik Pozna´ n University of Technology, Institute of Chemical Technology and Engineering, pl. M. Sklodowskiej-Curie 2, 60-965 Pozna´ n, Poland a r t i c l e i n f o Article history: Received 29 July 2014 Received in revised form 24 September 2014 Accepted 25 September 2014 Available online 2 October 2014 Keywords: Phenolic resins Degree of hardening Work of adhesion Inverse gas chromatography FTIR a b s t r a c t One of the most important stages during production of abrasive tools is their hardening. The degree of hardening is very important and influence toughness of the final product. During hardening process the cross-linking of the phenolic resins, used as a binder, occurs. Nowadays, there is no standard, accurate and simple method for the estimation of the hardening degree of abrasive tools. The procedure of the deter- mination of hardening degree of the binder (phenolic resins) by means of inverse gas chromatography (IGC) was presented in this paper. Results obtained by use of IGC derived method was verified by Soxhlet extraction and by FTIR method. Good agreement was found for results from IGC and Soxhlet extraction whereas those from FTIR were much lower. FTIR method supplies data concerning bulk properties not the surface as in case of IGC and Soxhlet methods. These results indicate that resins are more cross-linked on the surface than inside the material. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The production of the abrasive materials includes the fol- lowing stages: covering of abrasive materials by wetting agent, addition of the filler with the binding material, mixing of the components, stabilization of the composition and the hardening. The most important processes influencing the properties of the final product are the coverage of the abrasive materials, mixing and proper hardening [1,2]. The homogeneity of the mixture of semi-product increases the quality of the final product. The effec- tiveness of the hardening process depends also on the applied temperature programme. Although the determination of wettabil- ity of abrasive materials is relatively simple, the controlling of the hardening process is much more complicated. There is no easy standard industry method for controlling the hardening degree of such complex composites [3]. Brinell test is the most com- monly used test for assessment of hardness of abrasive tools. This method suffers from several disadvantages. The main disadvan- tage of this standard method is its very low repeatability and accuracy in case of such composites as abrasive tools. The results depend strongly on the place of ball pressing. Moreover, only final hardness of abrasive tool can be assessed. It is not possible to ∗ Corresponding author. E-mail addresses: Adam.Voelkel@put.poznan.pl, adamvoelkel@wp.pl (A. Voelkel). monitor the hardening process on-line. Viscoelastic parameters can be also applied for estimation of the degree of hardening. This method needs to use expensive equipment for dynamic rheolo- gical measurements. Moreover, it can be applied only for resins without additives or with nano/microfillers. The presence of filler nano/microparticles in resins can influence the rheological param- eters significantly. Inverse gas chromatography is an extension of classic gas chro- matography [4–8]. The word “inverse” means that the examined material is placed in the chromatographic column and its proper- ties are determined based on the retention behaviour of carefully selected test compounds. Inverse gas chromatography method is widely used for characterization of polymers and polymer blends [8], surfactants [9,10], biopolymers, solid food and petroleum pitches [1]. Inverse gas chromatography can be divided into inverse gas liquid and inverse gas solid chromatography. The obvious cri- terion of such discrimination is the state of the examined material placed in the column. The dominating retention mechanism is related to the temperature of IGC experiment. Polymeric materials might be characterized by using both surface parameters (surface free energy, surface acid/base properties and bulk parameters). The pertinence of IGC measurements to surface or bulk properties clearly depends on whether or not the probe molecules can diffuse into the bulk during the experiment. Retention volume measured at the temperature of IGC experiment higher than T g of the exam- ined polymer (or blend) results from the sum of surface and bulk sorption. Below T g mainly from the adsorption of probe molecules http://dx.doi.org/10.1016/j.chroma.2014.09.069 0021-9673/© 2014 Elsevier B.V. All rights reserved.