Ceramics-Silikáty 51, (3) 168 - 172 (2007) |
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FORMATION AND CHARACTERIZATION OF POLY(VINYL ALCOHOL–CO–VINYL ACETATE–CO–ITACONIC ACID)/PLASTER COMPOSITES - PART 2. COMPOSITE FORMATION AND CHARACTERISTICS
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El-Maghraby Hesham F. 1, Gedeon Ondřej 1, Khalil Abdel Aziz A. 2
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1 Department of Glass and Ceramics , Institute of Chemical Technology Prague, Technická 5, Praha 6, 166 28, Czech Republic
2 NRC, Department of Refractories, Ceramics and Building Materials, National Research Centre, Dokki, Cairo, 12622, Egypt
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Keywords: β-hemihydrate plaster, Polymer composites, Mechanical properties
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Poly(vinyl alcohol–co–vinyl acetate–co–itaconic acid) P(VA–VAc–It), ranging between 0.2 and 2.0 wt.%, were added to
β-hemihydrate plaster to form the plaster composites. Compressive and bending strengths of the composites were measured
and correlated with their scanning electron microscope (SEM) images. Results indicated that addition of the copolymer up
to 1.2 wt.% is improving the mechanical properties while the further addition of polymer decreased them. SEM showed the
role of polymer for interlocking among the set plaster grains. The neat set plaster contained comparatively higher porosity
and medium interlocking between the set grains; and consequently relatively low mechanical properties were observed. It is
suggested that the addition of the copolymer is forming a thin film around set plaster grains which acted to bind set grains,
increase the interlocking, and hence improve the mechanical properties of the composites. At an optimum copolymer concentration
of 1.2 wt.%, the best interlocking and strength results were thus obtained. |
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