INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Producción de materiales termoplásticos semicristalinos expandidos con agentes físicos en continuo y en batch
Autor/es:
C. J. PÉREZ; C. PIACENTINI; J. CARELLA
Lugar:
Iguazu, MIsiones
Reunión:
Congreso; 13° Congreso Internacional en Ciencia y Tecnologia de Metalurgia y Materiales; 2013
Institución organizadora:
Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Misiones
Resumen:
Thermoplastic semicrystalline materials expanded with physical agents show microcellular structures similar to the ones observed in their amorphous counterparts, together with many structural advantages and process drawbacks. Usable parts can be made with the conventional process in overheated steam, starting from preexpanded pellets, giving monolithic, tough structures due to the melting and cocrystallization of the pellets external layers. Parts obtained from amorphous polymers re fragile due to the slow interdiffusion process at temperatures just above the glass transition. Pellets of preexpanded polymer can be obtained by extrusion followed by cutting, or in batch process starting from precut pellets. The extrusion process is much more dependent on the melt extensional viscosity and its dependence on the shear rate applied to the melt, but its production scales is larger. The batch process requires more previous work, but can be adapted to polymers produced locally, and can be adapted to smaller production scales. Expanded polyolefins, polyethylenes and polypropylenes, have been produced in continuous processes using carbon dioxide and butane as expansion agents, and in batch processes using butane. Microcellular structures sizes distributions and closed cells fractions have been examined by electronic microscopy, and correlated with starting polymer properties and with additives used as nucleants and surfactants