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- 저자 : Inmaculada Suarez (검색결과 2 건)
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Rafael Van Grieken,Guillermo Calleja,Inmaculada Suarez,Javier Arranz-Andrés 한국고분자학회 2013 Macromolecular Research Vol.21 No.2
The slurry polymerization reactors on the industrial scale operate in continuous mode at low monomer conversion per pass to minimize mass and heat transfer limitations. Nevertheless, for the screening of catalytic systems,the laboratory tests are carried out using batch or semi-batch reactors. In this work, ethylene/propylene copolymers were synthesized in a semi-continuous reactor under similar conditions, where the only difference involves the modification of the feed ratio during the reaction. The key point of the control system is a micro-gas chromatograph (MGC), which analyzes the molar ratio ethylene (C2) to propylene (C3) in the gas phase during the reaction, and the composition in the liquid phase was calculated using the Soave-Redlich-Kwong equation of state. The effect of the ethylene/propylene copolymer microstructure has been studied using different techniques that allow us to conclude that the method of synthesis influences the comonomer distribution and the final copolymer properties.
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Molecular Characterization of Polypropylene Heterophasic Copolymers by Fractionation Techniques
Rafael A. García,Baudilio Coto,María-Teresa Expósito,Inmaculada Suarez,Almudena Fernández-Fernández,Susana Caveda 한국고분자학회 2011 Macromolecular Research Vol.19 No.8
Molecular microstructure, thermal properties and morphology of three polypropylene heterophasic copolymers (PHC) with similar comonomer content were characterized by gel permeation chromatography (GPC),differential scanning calorimetry (DSC), analytical and preparative temperature rising elution fractionation (TREF),scanning electron microscopy (SEM), and carbon nuclear magnetic resonance spectroscopy (13C NMR). These results indicate that there are no differences in solution and thermal properties between unfractionated copolymers. Nevertheless, a physical fractionation by crystallization of these copolymers was developed to carry out a detailed study. Four fractions at different temperatures were collected. The results showed that the PHC’s copolymers are composed by polypropylene, ethylene-propylene rubber (EPR) and, crystallisable sequences with different propylene and/or ethylene comonomers distribution. Despite the similar thermo-chemical properties shown by the raw PHC’s copolymers, the characterization of fractions displayed significant differences between them. These results suggest that the fractionation by crystallization allows the different components in which the PHC’s copolymers are based to be distinguished clearly, and obtain a more comprehensive sense of the molecular structure characterization.
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