Assessing the Feasibility of Coal As an Eco-Friendly Filler in Phenolic Resin Composites: A Study of Thermal and Structural Properties

Introduction: Due to the environmental concerns associated with using coal as the primary source of energy generation, there has been a recent surge of interest in exploring alternative utilization options for coal. The incorporation of coal particles as a filler in phenolic resin composites is a promising approach for composite development, owing to the similarity in the aromatic structure of both materials. This moiety similarity could promote increased interfacial connectivity and enhanced filler-composite compatibility.

In recent years, the demand for phenolic-based composite materials reinforced with fillers to reduce brittleness has risen due to their competitive performance and widespread use in the transportation, construction, and sports industries. Furthermore, fillers can provide an additional economic advantage by reducing cost; however, factors like filler effect on the curing process and the end use of the phenolic-based material must be considered. To fully exploit the potential of coal-based phenolic composites, it is essential to investigate the correlation between curing kinetics and network formation based on structural analysis. Understanding this correlation can provide insight into how different coal ranks can be leveraged to enhance certain mechanical and thermal properties of the composites, hereby promoting material advancement in the phenolic resin industry.

This work focuses on highlighting the effect of coal rank and content on the curing of phenolic resin using differential scanning calorimetry (DSC) and characterizing the cured composite samples using spectroscopic techniques.

Methods: DSC measurements were used to evaluate certain thermal properties like the peak temperature, heat of reaction, and activation energy. Two ranks of coal were selected due to functionality differences – anthracite and sub-bituminous coal type, and their content was utilized at varied filler weight percentages within the sample mix. The cured samples were characterized using FTIR and solid-state 13C NMR.

Results: The DSC analysis using a 40% filler weight content of both ranks of coal within the sample mix revealed an increased activation energy effect on the curing of phenolic resin with the sub-bituminous ranked coal (which could be attributed to the presence of a higher number of functional end groups) relative to the anthracite-ranked coal. Preliminary results from the FTIR analyses reveals a disappearance of aromatic isocyanate bonds (N=C=O) in the 40% coal-filled phenolic samples compared to the 100% phenolic, which suggests the possible interaction between the coal particles and the phenolic resin during cure. Results from the CNMR analysis was carried out to further elucidate the structural behavior of these cured samples and would be displayed during the poster presentation.