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The biaxial deformation and stress aging of polyetherimides as a way to change gas transport propertiesтезисы доклада
- Авторы: Alentiev A.Yu, Belov N.A., Kuznetsov A.A., Kechekyan A.S., Rusanov A.
- Сборник: 9-й Международный симпозиум по полиимидам и высокотехнологичным полимерам и материалам (STEPI 9). Stepi Abstracts
- Тезисы
- Год издания: 2013
- Место издания: Институт Шарля Герхарда Франция. Г. Монпелье
- Аннотация: The most progress in membrane science for the last decades was achieved in a field of the relationship between chemical structure of materials for gas separation and their gas permeation parameters. One of the summarizing of this relationship was made 20 years ago [1]. It was shown that similar changes in the values of the permeability and diffusion coefficients can be observed due to the introduction of the same groups into main chains and side groups of polymers that belong to different chemical classes (polycarbonates, polysulfones, polyimides, etc.). Demonstration of such effects can be found in the literature for various connector groups (-O-; -CH2-; -C(CH3)2-; -C(CF3)2-) or substituents (CH3, CF3, CH(CH3)2; Si(CH3)2) [2, 3]. These variations of the design of the membrane material affect chain stiffness, packing density of macromolecules and free volume as found e.g. by the Bondi method or measured using sophisticated physical techniques such as positron annihilation lifetime spectroscopy [4]. The synthesis of new polymers with these design elements was a paradigm of membrane material science The well accepted method of results presentation is a Reytlinger – Robeson diagram of permselectivity - permeability [5, 6]. But, there is a lot of facts that not only chemical structure, but also an ordering of the macromolecular structure [7] and interactions with residual solvent [8 – 11] can affect significantly the permselectivity of polymers. The dramatic dependence of permeability and permselectivity from the residual solvent and the protocol of film formation was appeared [9 – 11] for a few polyetherimides (PEI). In these works the 3 states of films were chosen. The first state (1) is drying up to constant weight under vacuum. In this state the PEI film with approximately 8% of hydrogen-bonding solvent (CHCl3) characterized the low selectivity. The second state (2) is annealing above the glass transition temperature for 2 hrs. In this state the PEI film without the residual solvent is characterized by the lowest permeability and highest selectivity in comparison with state 1. The third state (3) named as strained aging or keeping in isometric state for a prolonged period (2-3 months). The strain appears due to thinning of the film fixed at perimeter during the process of slow solvent evaporation. In this state the PEI film (with approximately 5% of residual solvent) is characterized by the same permeability as the state 1 but extremely highest selectivity in comparison with state 1. In these works chloroform was shown by FTIR and quantum chemical calculation to exist in the PEI films in the free form and in the hydrogen-bound form with Ph-O-Ph sites.
- Добавил в систему: Белов Николай Александрович