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OBTENTION OF POWDERED CERAMIC MATERIAL BY PYROLYSIS OF POLY [(DIMETHYLSILOXANE)-CO-(DIMETHYLSILAZANE)] COPOLYMERS AS PRECURSORS

DOI: 10.4067/S0717-97072006000200015

Keywords: poly[(dimethylsiloxane)-co-(dimethylsilazane) ] copolymers, thermal cured, pyrolysis, ceramic powder, morphology.

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Abstract:

a series of new poly(siloxane) and poly(silazane) derivates were synthesized by cationic ring opening mass copolymerization of the cyclic monomers octamethylcyclotetrasiloxane and hexamethylcyclotrisilazane, obtaining poly[(dimethylsiloxane)-co-(dimethylsilazane) ] copolymers with different concentrations of the comonomer units. the molar masses of the soluble fractions of the copolymers and of the macrocycles generated in the copolymerization reaction medium, were determined by gel permeation chromatography. thermogravimetric analysis shows that poly(dimethylsiloxane) is more stable than the copolymers and the homopolymer poly(dimethylsilazane). differential scanning calorimetry of poly(dimethylsilazane) presents a melting endotherm, indicating that this homopolymer is crystalline. the copolymers were characterized by ft-ir and 1h and 13c nmr spectroscopy.. the polymers were thermally cured and pyrolysed, obtaining ceramic powder. the morphology of the ceramic powder, studied by scanning electronic microscopy, corresponds to highly uniform spherical particles. the ceramic material was characterized by ft-ir. it was shown that these cyclic monomers copolymerize and that they constitute pre-polymer precursors of the powdered ceramic material since the products have si, c, n and o atoms

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