Estudio de propiedades térmicas y viscoelásticas de copolímeros de propileno y sus mezclas

VERóNICA RIECHERT; MARCELO DANIEL FAILLA; LIDIA MARíA QUINZANI

Concepción

Congreso; 15 Congreso Binacional de Metalurgia y Materiales Argentino-Chileno (SAM-CONAMET'15); 2015

Sociedad Chilena de Materiales

The polypropylene (PP) is asemicrystalline polymer widely used in the textile industry, packaging and automobileindustries because of its good processability and properties. However, itsapplications are limited because of their low toughness, especially at room andlow temperatures. This property can be improved by incorporation of á-olefinsby PP copolymerization process. Short amounts of these comonomers decreases thecrystallinity, melting point, stiffness and hardness of the PP, and produce anincrement in its impact resistance, flexibility and transparency. In consequence,copolymers of propylene and á-olefin are a widely used alternative in certainindustrial applications.Thermal and viscoelastic properties ofmixtures of random copolymers of PP- á-olefin with small amounts offunctionalized copolymers were studied. Four propylene-ethylene copolymers(PEC) and a propylene-ethylene-butylene terpolymer (PEBC) were employed. Smallamounts of this polymers where functionalized by grafting with maleic anhydride(PECg and PEBCg). This modification is widely used to increase the polarity ofan hydrophobic polymer in the elaboration of coatings, blends and polymericcomposites.Thermal properties were analyzed byDifferential Scanning Calorimetry (DSC). The crystallization temperature of thepolymers decreases with the augment in the comonomers concentration. Thecrystallization process to the grafted polymers were slight affected by thepresence of anhydride groups. The crystallization temperature (Tc) increasesfor the CPEs with 3% ethylene content, and decreases in the case of CPEB, dueto the nucleating effect of the anhydride groups and the decrease in themolecular weight. Thermal properties of the blends are similar than those ofthe original polymers. Viscoelastic properties were studied by rotationalrheology. The decrease in the molecular weight of the polymers reduces dynamicmodule values. Dynamic modules on blends are higher than those predicted by LogarithmicMixing Rule, suggesting an extra energy of mixing due to molecularinteractions, and probable immiscibility of the mixture phases.