Study of the mechanical and the thermal insulation properties of polyurethane coating containing chicken eggshell and rice husk ash as fillers

Abstract

Purpose

The main aim of this study was to examine the effects of chicken eggshell (CES) and rice husk ash (RHA) as fillers on the mechanical and the thermal insulation properties of polyurethane coatings.

Design/methodology/approach

CES and RHA were ground via ball milling set at different parameters, and the smallest particles size obtained were selected and used as fillers. Fillers of different weight proportions were mixed with other components such as binder, solvent and pigment to form various coating formulations and test samples were made via dip coating. A series of characterisations were conducted to analyse the thermal and mechanical properties of the coating.

Findings

The smallest particle size of CES and RHA was obtained after both of them had undergone grinding process at 400 rpm within 180 min. Morphological studies revealed that CES and RHA have irregular shape and high porosity. In crystallographic analysis, CES mainly composed of pure calcite crystal structure and RHA contained amorphous silica. Both of fillers were found thermally stable up to 520 and 710°C for RHA and CES, respectively. In RHA individual system, as the RHA proportion increases, the thermal conductivity of the coating declined. In contrast, in the CES coating system, the thermal conductivity demonstrated an opposite trend. Thermal gravimetric analysis results displayed that by adding hybrid fillers, the residue weight and the thermal stability of the coatings were increased. In addition, the adhesion strength of the coating was increased as the filler weight content increased.

Research limitations/implications

Fillers with nano-range size were expected to be produced in this research for better performance of the coating. However, the obtained fillers were limited to micron size through dry grinding method. Another drawback in this research was the coating technique which is dip coating. The coated substrates do not have uniform coating thickness and this subsequently influenced the performance.

Originality/value

A novel attempt has been made to study the formulation coating system by mixing CES and RHA as fillers which is also known as a hybrid system.

Citation

Ang, B.C., Ahmad, N., Ong, Z.C., Cheok, S.C. and Chan, H.F. (2016), "Study of the mechanical and the thermal insulation properties of polyurethane coating containing chicken eggshell and rice husk ash as fillers", Pigment & Resin Technology, Vol. 45 No. 5, pp. 313-319. https://doi.org/10.1108/PRT-05-2015-0050