Chemical surface modification of calcium carbonate particles with stearic acid using different treating methods

Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. However, the method of application of the SA treatments has a strong influence on CaCO3 thermoplastic composite's interfacial structure and distribution. Several of papers describe the promising effects of SA surface treatment, but few compare the treatment process and its effect on the properties of the final thermoplastic composite. In the current study, we assessed a new SA treatment method, namely, complex treatment for polymer composite fabrication with HDPE. Subsequently, a comparative study was performed between the complex process and the other existing methods. The composites were assessed using different experiments included scanning electron microscopy (SEM), void content, density, wettability, differential scanning calorimetry (DSC), and tensile tests. It was observed that the complex surface treatment yielded composites with a significantly lower voids content and higher density compared to other surface treatments. This indicates that after the complex treatment process, the CaCO3 particles and HDPE matrix are more tightly packed than other methods. DSC and wettability results suggest that the wet and complex treated CaCO3 composites had a significantly higher heat of fusion and moisture resistance compared to the dry treated CaCO3 composites. Furthermore, wet and complex treated CaCO3 composites have a significantly higher tensile strength than the composites containing untreated and dry treated CaCO3. This is mainly because the wet and complex treatment processes have increased adsorption density of stearate, which enhances the interfacial interaction between matrix and filler. These results confirm that the chemical adsorption of the surfactant ions at the solid-liquid interface is higher than at other interface. From this study, it was concluded that the utilization of the complex method minimised the negative effects of void coalescence provides key information for the improvement of existing processes. (C) 2016 Elsevier B.V. All rights reserved.