Synthesis and Characterization of Low-Cost Cresol-Based Benzoxazine Resins as Potential Binders in Abrasive Composites.

Artur Jamrozik,Paulina Jakubowska,Daniel Baranowski,Łukasz Klapiszewski,Adam Voelkel,Teofil Jesionowski,Mateusz Barczewski,Grzegorz Framski,Beata Strzemiecka

doi:10.3390/ma13132995

Abstract

A series of cresol-based benzoxazines were synthesized for potential application as a polymer matrix in abrasive composites. The chemical structures of the obtained benzoxazine resins were investigated in detail using Fourier transform infrared spectroscopy (FTIR) and hydrogen-1 as well as carbon-13 nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR) with an additional analysis using two-dimensional NMR techniques (2D NMR 1H-1H COSY, 1H-13C gHSQC and gHMBC). Structural analysis confirmed the presence of vibrations of -O-C-N- at ~950 cm−1 wavenumber, characteristic for an oxazine ring. The thermal properties of benzoxazine monomers were examined using differential scanning calorimetry (DSC) analysis. The polymerization enthalpy varied from 143.2 J/g to 287.8 J/g. Thermal stability of cresol-based benzoxazines was determined using thermogravimetry (TGA) analysis with additional analysis of the amount of volatile organic compounds (VOC) emitted from the synthesized benzoxazines during their crosslinking by static headspace coupled with gas chromatography technique (HS-GC). The amount of residual mass significantly differed between all synthesized polybenzoxazines in the range from 8.4% to 21.2%. The total VOC emission for benzoxazines decreased by 46–77% in reference to a conventional phenolic binder. The efficiency of abrasive composites with the benzoxazine matrix was evaluated based on abrasion tests. Performed analyses confirmed successful synthesis and proper chemical structure of cresol-based benzoxazines. All the experiments indicated that benzoxazines based on different cresol isomers significantly differ from each other. Good thermal performance and stability of the abrasive composites with the polybenzoxazine matrix and significantly lower VOC emission allow us to state that benzoxazines can be a promising and valuable alternative to the phenolics and a new path for the development of modern, eco-friendly abrasives.

Highlights

Surface quality is one of the most important characteristics of products which consist of metal, stone, wood and polymers
The results presented in this study demonstrate that cresol-based benzoxazines can be synthesized according to the Mannich reaction mechanism with good efficiency
Fourier transform infrared spectroscopy (FTIR) and NMR techniques confirmed that the resulting compounds possessed the expected chemical structure and functional groups

Summary

Introduction

Surface quality is one of the most important characteristics of products which consist of metal, stone, wood and polymers. The gradual release of phenol, formaldehyde and other VOCs at almost every stage of manufacturing of abrasive tools, from mixing of raw materials to hardening in furnaces, is a well-known fact [7,8,9,10]. This phenomenon concerns many other materials containing phenolics, e.g., printed circuit boards and wood-based panels [11,12]. The adhesion between polymer matrix and the abrasive grain is a property of the tool that is very difficult to determine. Benzoxazines are a type of thermoset polymers which exhibit basic properties that meet the general requirements imposed by the abrasive industry

Methods

Results

Conclusion