Effects of membrane thickness and heat treatment on the gas transport properties of membranes based on P84 polyimide

Abstract

P84 polyimide membranes with thicknesses ranging from 6 to 310 lm were successfully fabricated by spin coating. The glass transition temperature of the P84 powder was found to be 315 C using differential scanning calorimetry, whereas its decomposition temperature was 536 C using thermogravimetric analysis. Scanning electron microscopy was used to examine the morphology of the membranes. The permeability of single gas (He, N 2 , O 2 , and CO 2 ) and the ideal selectivity of gas pair (O 2 /N 2 , He/ CO 2 , CO 2 /N 2 , and He/O 2 ), as a function of membrane thickness, were determined. The results showed that the permeability of a single gas increased with increasing membrane thickness, whereas the selectivity of a given gas pair was nearly independent of the membrane thickness. The average selectivity of O 2 /N 2 , He/CO 2 , CO 2 /N 2 , and He/O 2 were found to be 8.2, 10.0, 12.9, and 15.8, respectively. The effects of heat treatment on the membrane morphology and gas transport properties were investigated for three annealing temperatures, i.e., 80 C, 200 C, and 315 C. The membrane annealed at 315 C was cracked due to the stress sustained either during heating or cooling, thereby resulting in little or no selectivity. The permeabilities of P84-118 membrane (118 lm thickness) annealed at 80 C were 16.

A Study of the Reinforcement Effect of MWCNTs onto Polyimide Flat Sheet Membranes

“…Similar permeability values for polyimide P84 flat sheet membranes are also reported in the literature [ 60 , 61 ]. In the case of the single polyimide membranes, the low values of gas permeability and the fact that the temperature has positive influence are the two main characteristics of the membranes’ behavior.…”

“…The pure polyimide membrane provides, at 25 • C, permeability values of 9.6, 9.9, 8.9, 0.6, 0.3, 0.1, and 0.2 Barrer for He, H 2 , CO 2 , O 2 , CO, N 2 , and CH 4 , respectively. Similar permeability values for polyimide P84 flat sheet membranes are also reported in the literature [60,61]. In the case of the single polyimide membranes, the low values of gas permeability and the fact that the temperature has positive influence are the two main characteristics of the membranes' behavior.…”

Effect of relative humidity and temperature on gas transport in Matrimid®: Experimental study and modeling

“…After this first drying procedure, the sample was annealed at 200 1C under vacuum for 24 h, in order to ensure the complete solvent removal. As often showed by many authors, the polymer thermal history can significantly affect the mass transport properties, as well as the performance of glassy polymer membranes [7,9,40]. However, it was observed that the pretreatment of Matrimid s films at 200 1C is able to produce membranes with gas transport properties stable for a period of at least 6 months, as no significant aging was detected from gas permeability measurements [41].…”

“…Several polyimide materials, based on different diamines and dianhydride moieties, have been characterized for gas separation applications, and some of them are currently employed in commercial membrane separation modules, used for oxygen enriched air production, biogas and natural gas upgrading, or hydrogen recovery from syngas [6][7][8].…”

The utilization of micro-mesoporous carbon-based filler in the P84 hollow fibre membrane for gas separation

“…The dense layer thickness gradually increased as the fillers loading amount improved. The increment in the dense layer was originated from the improvement of dope solution viscosity and thus, it improved permeability [51].…”