Título
Membranes from rigid block hexafluoro copolyaramides: Effect of block lengths on gas permeation and ideal separation factors
Autor
MANUEL DE JESUS AGUILAR VEGA
Nivel de Acceso
Acceso Abierto
Materias
Resumen o descripción
Dense membranes were prepared from three different rigid block copolyaramides, one block bearing two
bulky hexafluoro (–CF3) groups and a lateral tert-butyl group (–C–(CH3)3), and the second block without
the lateral tert-butyl group. The effect of block length, at constant comonomer concentration, on thermal
properties as well as gas permeability coefficients and separation factors is analyzed. The results indicate
that block copolyaramide membranes present a density that is quite similar but slightly lower, as the
length of the blocks that form the copolymer increase, that falls in between the density of the
homopolyamides. The fractional free volume, FFV, increases in the block copolymers as the block length
increases. This result is attributed to an inefficient packing of the copolymer molecules as the block
length gets larger. As a result, the permeability and diffusion coefficients in the block copolymers are
larger than those in the parent homopolymers. The gas separation factors remain with a minimum
change even though there is a gain in gas permeability; therefore, block copolymerization using highly
rigid blocks, due to differences in packing, presents the advantage of a higher gas permeability coefficient
with a minimum loss in selectivity. The rigidity of these copolymers presents advantages for high
temperature applications.
Fecha de publicación
15 de septiembre de 2013
Tipo de publicación
Artículo
Recurso de información
Formato
application/pdf
Repositorio Orígen
Repositorio Institucional CICY
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