The fractal characteristic of porous coatings prepared with ground calcium carbonate
Guodong Liu, Shaanxi University of Science &Technology, Xi’an, China, Zhaoqing Lu, Shaanxi University of Science & Technology, China, Meiyun Zhang, Shaanxi University of Science &Technology, China, Cathy Ridgway and Patrick Gane, Omya International AG, Oftringen, Switzerland
To enhance the print quality of coated paper, the methodology of adjusting the porous structure of the coating is frequently employed to obtain particular imbibition characteristics for print liquids. Due to the complex and random pore structure of coating materials, it is not plausible to use Euclidean geometry to describe the stochastic morphology of the pore surface. Therefore, we use the non-Euclidean fractal geometry to characterise the irregular internal pore surface and offer some evidences for the fractal nature of coating materials. To exemplify, we adopt an extensively used mineral coating pigment, ground calcium carbonate (GCC), to analyse the structural characteristics based on the fractal method. The fractal dimensions of these materials accordingly are calculated by the classical fractal Frenkel-Halsey-Hill (FHH) model on the basis of isothermal nitrogen sorption measurement. The fractal feature of GCC coatings is represented by the fractal dimensions, showing excellent correlation with the observed structure data (R2 = 0.900~0.993). In addition, the relationship between spontaneous liquid imbibition into GCC coatings and their fractal dimensions is also discussed to support this model further. Thus, in principle, it is possible to adjust the porous structural parameters and internal surface morphology via fractal dimension to perform specific functions.
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent. Open Access: Articles not available through Gold Open Access may be purchased by credit card as a pdf file, to be downloaded within 24 h after ordering, at a price of 22 EUR per article. (Value added tax may apply depending on your location, which you enter at payment logout.) Such articles have Green Open Access, i.e. authors may share articles on their personal non-commerical homepage immediately after publication on the website and download them to non-commercial hosting platforms one year after publication in a full issue of NPPRJ. ISSN: 0283-2631