Estudo de novos suportes para catalisadores de ziegler-natta

AUTOR(ES)
DATA DE PUBLICAÇÃO

1992

RESUMO

ln this work titanium tetrachloride -TiCl4- was heterogenized in novel supports with the objective of producing new Ziegler-Natta heterogeneous cataIysts. The organic supports tested were: atactic poly(propylene) -aPP, natural rubber -NR, poly(vinylchloride) -PVC, poly(4-vinylpyridine) -P4VP- with 2% and 25% divinylbenzene (DVB) and the Merrifield polymer. The aPP, NR and PVC were functionalized through chlorination and the Merrifield polymer was functionalized with cyclopentadienyl. The obtained catalysts were used for olefin polymerization. The heterogenized catalysts that showed the best activity to ethylene polymerization was the chlorinated aPPsystem (20,7 kg PE/mol Ti.h.bar). In the non chlorinated series, the supported TiCl4 showed lower activity. The best one being the P4VP with 25% DVB (7,9 kg PE/moI Ti.h.bar). The viscosimetric average molecular weight -v- of the poly(ethylens) -PE- varied from 300 to 1500 kg/mol, depending on the system. The inorganic supports studied were chrysotile and titanium oxide - TiO2, TiCI4 was heterogenized in the desfibrilized and termically dehydroxilated chrysotile. Its activity, to the ethylene polymerization, was 14,3 kg PE/moI Ti.h.bar and the v of the obtained PE was up to 1900 kg/mol. A method for the activation of TiO2 was developed through reduction with alquilaluminium. The heterogenized TiCl4 was partially reduced before the polymerization. This catalyst showed high activity to ethylene polymerization (7600 kg PE/mol Ti.h.bar) and to propylene polymerization (3000 kg PP/mol Ti.h.bar). The activity of this system was related to time and temperature of polymerization. This catalyst has unusually high stereoselectivity (isotacticity of poly(propylene) >93%). The v of poly(propylene) was up to 370 kg/mol and the of PE up to 2000 kg/mol. The v of the polymer was controlable by hydrogen addition during the polymerization reaction.

ASSUNTO(S)

polimeros e polimerização quimica inorganica

ACESSO AO ARTIGO

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