Interactions between Organic and Inorganic Phases in PA- and PU/PA-Modified-Cement-Based Materials
In this paper, two types of acrylics, polyacrylate (PA), a copolymer of methyl methacrylate, acrylic acid, and others, and polyurethane-modified PA (PU/PA), are investigated in their interactions with inorganic phases in polymer-modified cement-based mixtures and in their mechanisms in improving both mechanical properties and durability of cement-based materials. In these investigations, the total organic carbon content (TOC) method is used to study the adsorption of polymer particles in mixtures. An aqueous tube test, x-ray diffraction (XRD), thermal gravity analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) are employed to study the possible chemical reactions between the latexes and cement hydrates. Scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDX) are used to observe the film formation and the final morphology of PA- and PU/PA-modified mortars. PU/PA latex is found to be relatively stable, and the behaviors of PU/PA-modified mixtures can be explained by Ohama's model. On the other hand, molecules of PA latex are very active in cement-based mixtures. Moreover, the normal assumption that polymer particles are uniformly dispersed in aqueous phase is invalid in PA-modified mixtures. Chemical reactions occur between PA latex and cement hydrates, especially calcium hydroxide. In the final comatrix of PA-modified mortar, no PA film with high purity can be distinguished by SEM/EDX. Based on the findings, a new model with a four-step procedure is proposed to explain the behaviors and properties of PA latex-modified cement-based materials.
H. Ma et al., "Interactions between Organic and Inorganic Phases in PA- and PU/PA-Modified-Cement-Based Materials," Journal of Materials in Civil Engineering, vol. 23, no. 10, pp. 1412-1421, American Society of Civil Engineers (ASCE), Mar 2011.
The definitive version is available at http://dx.doi.org/10.1061/(ASCE)MT.1943-5533.0000302
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Acrylic Acids; Aqueous Phase; Cement Based Material; Cement Hydrates; Cement-based; Co-matrix; Energy Dispersive X-ray; Film Formations; FTIR; High Purity; Inorganic Phasis; Interaction; Methyl Methacrylates; New Model; Polymer Particles; Polymer-modified Mortars; Thermal Gravity Analysis; Total Organic Carbon Content; Adsorption; Carboxylic Acids; Cements; Chemical Analysis; Durability; Esters; Fourier Transform Infrared Spectroscopy; Hydrated Lime; Hydrates; Hydration; Latexes; Mixtures; Mortar; Organic Carbon; Polyacrylates; Polymers; Scanning Electron Microscopy; X Ray Diffraction; X Ray Diffraction Analysis; Bone Cement; Adsorption; Cement; Chemical Reaction; Durability; Mechanical Property; Polymer; Total Organic Carbon; Interaction; PA; PU/PA
International Standard Serial Number (ISSN)
Article - Journal
© 2011 American Society of Civil Engineers (ASCE), All rights reserved.