Poly (2,6-dimethyl-1,4-phenylene oxide) hollow fibres for gas separation

Hollow fibres used for gas separation applications need to have good mechanical strength and excellent gas separation properties. The production of hollow fibres by the dry-wet spinning process involves many variables, each having the potential to affect these properties.;This is a systematic study of the effect of several variables in the spinning process on the dimensions, morphology and CO2/CH 4 gas separation performance of poly(2,6-dimethyl 1,4-phenylene oxide) (PPO). Hollow fibres were prepared by the dry-wet spinning method from solutions of PPO in trichloroethylene using the non-solvent methanol as the bore liquid and for the gelation bath. The variables studied were the length of the air gap, the flowrates of the bore liquid and polymer solution and the presence of 2-ethyl-1-hexanol in the polymer solution used for spinning. A one-factor-at-a-time approach was used to show how these variables affected the outer diameter; wall thickness and carbon dioxide and methane permeate flux of the hollow fibres. A factorial design was used to determine which of the effects were significant and if there were any interactions between the variables that also affected the hollow fibre properties. The results were used to develop models for each of the five response variables as a function of those spinning variables that were found to significant.;The outer diameters of the fibres produced within the constraints of the factorial design ranged from 0.39--0.6 mm, and the wall thickness from 0.018--0.045 mm. The outer diameter of the fibres was found to decrease with increasing air gap, decreasing polymer solution flowrate and decreasing bore liquid flowrate. The wall thickness was found to increase with increasing polymer solution flowrate, and decreasing bore liquid flowrate. The interaction between the presence of 2-ethyl-1-hexanol and the bore liquid flowrate had a significant effect on the hollow fibre wall thickness. None of the interactions between the other variables were found to have a significant effect on the hollow fibre dimensions.;The methane permeate flux for the hollow fibres produced within the constraints of the factorial design ranged from 1.52 x 10-11--4.8 x 10-11 mol/m2.s.Pa, and the carbon dioxide permeate flux from 3.52 x 10-10--1.25 x 10-9 mol/m2.s.Pa. (Abstract shortened by UMI.)...