title: Surface modification of purified fly ash and application in polymer.
abstract: With the growing general concern about the pollution by fly ash (FA), there has been global interest in its utilization. Purified FA or FA micro-beads are suitable as polymer filling materials because of their density, good dispersity and fluidity of globular particles. However, FA as a filler has not been widely used up to now on account of low whiteness values and low friction of untreated FA surface. In order to improve the FA quality, a surface modification method by using isothermal heating is proposed in this paper. Preparation of composite fly ash (CFA) in the Ca(OH)(2)-H(2)O-CO(2) system is described. Good coating results on FA surfaces can be achieved under suitable operating parameters. The characteristics of CFA are discussed and analyzed based on data from X-ray diffraction, scanning electron microscopy (SEM), infrared spectra, and BET multiple-point nitrogen adsorption method. Feedstocks with less than 45 microm grain size, 2.86 m(2) g(-1) specific surface area, and 36.68 whiteness value revealed an increase in specific surface area ranging from 8.69 to 10.01 m(2) g(-1) and an increase in whiteness values ranging from 63.67 to 73.13 after coating. A SEM study allowed a detailed determination of the morphology of the surface roughness. Filling tests also show that a rough surface of the CFA enhances contact opportunities and improves the interface between polymer and CFA blended with polypropylene (PP).
authors.affiliation: Powder Technology R & D Group, Department of Materials Science and Engineering, Tsinghua University, Beijing, China.
authors.forename: Yu-Fen
authors.initials: YF
authors.lastname: Yang
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Gai
authors.forename: Zhen-Fang
authors.initials: ZF
authors.lastname: Cai
authors.forename: Qing-Ru
authors.initials: QR
authors.lastname: Chen
mesh_terms: D002244:Carbon / Q000737:chemistry* / Q000302:isolation & purification*; D060729:Coal Ash; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D052638:Particulate Matter; D011108:Polymers / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D060729:Coal Ash; D052638:Particulate Matter; D011108:Polymers; D017640:Silicates; D002244:Carbon