Subambient temperature CO(2) and light gas permeation through segmented block copolymers with tailored soft phase.

The permeation properties of a series of block copolymers based on poly(ethylene oxide)-ran-poly(propylene oxide) (PEO-ran-PPO) soft segments and monodisperse tetra-amide (T6T6T) hard segments have been studied. The polyether soft segment used in the current study differs from the commonly used pure poly(ethylene oxide) (PEO) soft segment by the fact that it contains 25 wt % randomly distributed poly(propylene oxide) (PPO). The presence of the methyl group of PPO suppresses crystallization of the soft segment and strongly improves the permeability of these materials, especially at subambient temperatures.

Elastic properties of thermoplastic elastomers based on poly(tetramethylene oxide) and monodisperse amide segments.

The elastic properties of thermoplastic elastomers based on poly(tetramethylene oxide) and monodisperse amide hard segments (HS) were studied in compression and tensile mode as well as with stress relaxation (SR) measurements. For these copolymers the compression set values were low and increased with the modulus and temperature. At low strains (<50%) the tensile set (TS) values were low and the strain recovered almost completely with time.

The tensile properties of poly(ethylene oxide)-based segmented block copolymers in the dry and wet state.

The tensile properties of poly(ethylene oxide)-based segmented block copolymers were studied in the dry and wet state. The hard segments were made up of monodisperse crystallisable tetra-amide segments (T6T6T) comprising terephthalate (T) and hexamethylenediamine (6) groups. The length of the segments making up the soft phase was varied from 600 to 10,000 g/mol.

Tensile properties of segmented block copolymers with monodisperse hard segments.

The tensile properties of segmented block copolymers with mono-disperse hard segments were studied with respect to the hard segment content (16-44 wt.%) and the temperature (20-110 °C). The copolymers were comprised of poly(tetramethylene oxide) segments with the molecular weights of 650-2,900 Da and of mono-disperse bisester-tetra-amide segments (T6A6T) based on adipic acid (A), terephthalic acid (T) and hexamethylene diamine (6).

Aprospective study of urinary-tract infections in a Dutch general practice.

In a Dutch general practice the adult female population was screened for asymptomatic bacteriuria (A.B.) by repeated urine culture after vulval cleansing.