Effect of Immobilization of Phenolic Antioxidant on Thermo-Oxidative Stability and Aging of Poly(1-trimethylsilyl-1-propyne) in View of Membrane Application.

Sergey Shishatskiy,Valeriy Khotimskiy,Petra Merten,Ivan Levin,Vladimir Makrushin,Samira Matson

doi:10.3390/polym14030462

Abstract

The effect of phenolic antioxidant Irganox 1076 on the structure and gas permeation behavior of poly(1-trimethylsilyl-1-propyne) (PTMSP) was investigated. Isotropic films as well as thin film composite membranes (TFCM) from pure PTMSP and with added antioxidant (0.02 wt%) were prepared. PTMSP with antioxidant has a significantly higher thermal degradation stability in comparison to pure polymer. The thermal annealing of isotropic films of PTMSP with antioxidant was carried out at 140 °C. It revealed the stability of gas permeation properties for a minimum of up to 500 h of total heating time after a modest permeation values decrease in the first 48 h. X-ray diffraction data indicate a decrease in interchain distances during the heat treatment of isotropic films and indicate an increase in the packing density of macromolecules during thermally activated relaxation. Isotropic films and TFCMs from pure PTMSP and with antioxidant stabilizer were tested under conditions of constant O2 and N2 flow. The physical aging of thick and composite PTMSP membranes point out the necessity of thermal annealing for obtaining PTMSP-based membranes with predictable properties.

Highlights

Glassy poly(1-trimethylsilyl-1-propyne) (PTMSP) has an extremely high fractional free volume (>0.3), which determines its extremely high permeability to gases and vapors, as well as the highest selectivity of condensable hydrocarbons over permanent gases, which is necessary for the recovery of organic vapors [1,2,3,4,5]
Due to the nonequilibrium state of PTMSP, physical aging is observed, which is a characteristic property of glassy polymers
One can observe that the introduction of a stabilizer in the amount of 0.02 wt% leads to a decrease in the permeability coefficients in comparison to pure PTMSP film

Summary

Introduction

Glassy poly(1-trimethylsilyl-1-propyne) (PTMSP) has an extremely high fractional free volume (>0.3), which determines its extremely high permeability to gases and vapors, as well as the highest selectivity of condensable hydrocarbons over permanent gases, which is necessary for the recovery of organic vapors [1,2,3,4,5]. An increase in O2 /N2 and H2 /N2 selectivity along with a decrease in permeability was noted for aged PTMSP films [13,14] This fact should be attributed to a drop in the diffusion coefficients due to an increase in the density of the polymer with time, which is confirmed by a decrease in the interchain distance in the polymer. The authors interpreted the results from the standpoint of relaxation and an increase in the polymer packing density under the action of heating. It was shown in [16] that

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Results

Conclusion