Ceramics-polymer composites based on porous ceramic material with porosity gradient
Mikołaj Szafran, Gabriel Rokicki, Ewa Bobryk, Aleksander Lamenta Politechnika Warszawska, Wydział Chemiczny, ul. Noakowskiego 3, 00-664 Warszawa
Annals 4 No. 11, 2004 pages 231-236
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abstract In the paper preliminary studies on the preparation of ceramics-polymer composites based on porous ceramic material with porosity gradient are presented. The porous ceramic material was obtained applying lamination and sintering of cera-mic tapes. The tapes were prepared using tape-casting method. Al2O3 of average grain size 0.5 μm and specific surface measu-red by the BET method equal to 8.28 m2/g was used as a ceramic powder. Ceramic tapes were prepared using water or organic solvent as a dispersing medium. In the water system poly(vinyl alcohol) plasticized with glycerin was used as a polymeric binder, whereas in nonaqueous system poly(vinyl butyral) plasticized with dibutyl phtalate was used. Microcellulose of particles size 25÷75 μm was applied as a porophore. To obtain porous ceramic material green ceramic tapes of different composition were laminated at 110°C (Fig. 1), and sintered at 1550°C for 1 h. The properties of the ceramic samples are presented in Table 1. To obtain ceramics-polymer composite dimethacrylic macromonomers were introduced into pores of the obtained ceramic samples. Macromonomers were synthesized by copolymerization of dilactide and trimethylene carbonate (1:1; 1:3; 3:1) and then reacted with methacryloyl chloride according to the scheme in Figure 2. Macromonomers were introduced into porous samples under reduced pressure and polymerized at room temperature using radical initiator. The degree of pores filling was in the range 60÷80%. The pictures of the ceramics-polymer fractures are presented in Figure 5. The mechanical properties investigations of the composites indicated that the strain-stress behaviour is different from this for samples without polymer in pores. Mechanical strength of composite samples was 10 to 20% higher in comparison with that of unmodified ones (Fig. 6 and Tab. 3). The new method of obtaining ceramic material with gradient porosity that can be easily transform into ceramics-polymer composites was developed. Key words: ceramics-polymer composites, porosity gradient, biodegradable polymer