Effect of film thickness and filler properties on sulphuric acid permeation in various commercially available epoxy mortar coatings.
The performance of various commercially available epoxy mortar coatings was compared by measuring their sulphuric acid diffusivity. Apparent diffusivities, which were measured gravimetrically, were found to be dependent on coating tortuosity. In composite materials like epoxy mortars, the tortuosity was determined by filler properties and polymer alignment. Tortuosity was found to depend on the filler size, their dispersion, filler aspect ratio and concentration. The order and greater alignment of polymer aggregates, which characterises thinner coatings effects higher tortuosity and thus lower permeabilities. The result is that sulphuric acid diffusivities were observed to increase with coating thickness, which challenges the notion that greater coating thicknesses provide greater protection or environmental barrier. The effect of film thickness and filler properties observed in this study has significant implications to the current selection of coatings and sewer protection.
School of Chemical and Biomolecular Engineering, The University of Sydney, NSW 2006, Australia. marjorie.valix@sydney.edu.au
M
M
Valix
H
H
Mineyama
C
C
Chen
W H
WH
Cheung
J
J
Shi
H
H
Bustamante
D004058:Diffusion; D004852:Epoxy Compounds / Q000737:chemistry*; D008420:Manufactured Materials / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D010539:Permeability; D011108:Polymers / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013464:Sulfuric Acids / Q000737:chemistry*
D004852:Epoxy Compounds; D011108:Polymers; D013464:Sulfuric Acids; C033158:sulfuric acid