Aspectos cinéticos de la cristalización isoterma del polipropileno isotáctico en sus mezclas con un copolímero de etileno-alcohol vinílico
- Ares-Pernas, Ana
- Marco, C.
- Gómez, M.
- Ellis, G.
- Abad López, María José
- Barral, Luis
ISSN: 0121-6651, 1988-4206
Ano de publicación: 2009
Volume: 10
Número: 6
Páxinas: 297-309
Tipo: Artigo
Outras publicacións en: Revista Iberoamericana de Polímeros
Resumo
The isothermal crystallization behaviour from the melt of isotactic polypropylene in blends with 10 - 40% by weight of an ethylene-vinyl alcohol copolymer has been analysed. The influence of an ethylene-methacrylic acid copolymer compatibilizing agent was studied. The rate constants of the isothermal crystallization process of iPP were determined from the times associated with 50% crystalline transformation. The values of basal interfacial free energies associated with the nucleation stage, corresponding with crystallization regime III, demonstrate the nucleation activity of small crystals of the EVOH copolymer on the crystalline nucleation of iPP in binary blends, and an increase in the crystallization rate. The presence of the interfacial agent generates a compatibilizing effect which extinguishes this nucleating activity, and increases the free energy of nucleation, with the consequent reduction in the crystallization rate of polypropylene.