No 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.

This paper presents the results of a study of the effect of thermally activated relaxation on the gas permeability of films prepared from poly(1-trimethylsilyl-1-propyne) (PTMSP) of different configurational composition (the content of cis-units varies from 40 to 80%). Films of both pure PTMSP and those prepared with the addition of the antioxidant Irganox 1076 have been subjected to heat treatment. When polymer films have been heated without a stabilizer, the cis-enriched sample of PTMSP (80% cis-units) showed the highest stability. The addition of an antioxidant significantly increases the resistance of PTMSP films to thermal effects, while the trans-enriched sample (40% of cis-units) has shown the highest resistance. It has been found that in the first 40 h of heating, the trans-enriched PTMSP shows a faster relaxation compared to the cisenriched samples, and upon further heat treatment, the decrease in the permeability coefficients occurs more slowly and at approximately the same rate for all samples. It is shown that the thermally activated relaxation of PTMSP films leads to an increase in the ideal selectivity, which is especially noticeable for the CO 2 /N 2 pair (reaches 8.2 for PTMSP samples containing 40 and 80% cis-units). X-ray diffraction data indicate a decrease in interplanar distances upon heat treatment and indicate an increase in the packing density of macromolecules during thermally activated relaxation.