Ceramics-Silikáty 51 (3) 168-172 (2007)

FORMATION AND CHARACTERIZATION OF POLY(VINYL ALCOHOL–CO–VINYL ACETATE–CO–ITACONIC ACID)/PLASTER COMPOSITES

PART 2. COMPOSITE FORMATION AND CHARACTERISTICS

H. F. El-Maghraby , O. Gedeon , A. A. Khalil

Poly(vinyl alcohol–co–vinyl acetate–co–itaconic acid) P(VA–VAc–It), ranging between 0.2 and 2.0 wt.%, were added to b-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.

Keywords: -hemihydrate plaster, Polymer composites, Mechanical properties