The polyimide may be in the form of a membrane and the membrane, after treatment according to the process of the invention, may be suitable for use in a membrane-based separation technique, for example gas separation, filtration, microfiltration, ultrafiltration, reverse osmosis or pervaporation.
The extent of crosslinking was monitored through differentialscanning calorimetry measurements. The influence of crosslinking on the physical and transport properties was measured.
Activation procedures included irradiation UV,and electron-beam and thermal at temperatures above and below theglass transition temperature of the polymer. Surface treatment by irradiation resulted in modest improvements in separationselectivity with little reduction in fast gas flux.
Thisresulted in negligible improvements in chemical resistance or thermal stability.
Irradiation using an electron-beam appears tohave lead to polymer chain scission resulting in a reduced thermal stability and glass transition temperature.
Thermal treatmentsresulted in high or complete ethynyl conversion. Complete conversion of the ethynyl units resulted in marked improvementsin the resistance to chemicals, thermal stability, and gas selectivity.
Because the reaction temperature was higher than theglass transition temperature of the fully reacted blend, collapse of the membrane substructure occurred accompanied by areduction in membrane permeance. Conversely, thermal treatment at C resulted in a marked increase in the permeanceof the membranes with a small reduction in selectivity.
Gas transport; Asymmetric membranes; Ethynyl-terminated monomer; Crosslinking; Polyetherimide1. IntroductionCrosslinking of a polymer matrix may influencephysical properties and the ability of the material totransport and separate gases.
Because crosslinking Corresponding author. Restriction of the polymerchain mobility can impede gas transport since the dif-fusion of gas molecules through a polymer involvesthe cooperative motion of chain segments .
Gaseswith larger molecular diameters are more severelyimpacted than those with smaller diameters. Thus,crosslinking can lead to improved separation selec-tivity but usually only at the expense of reduced gaspermeation rates. S 01 C. In terms ofcrosslinking agents, a wide variety of chemistrieshave been employed.
Most result in densification andreduced permeability while a few occur without sig-nificant volume contraction or modifications in trans-port .
The energy source employed to promote thecrosslinking has been shown to influence properties. Two trends have been demonstrated in the literature: In this study, we will reporton the crosslinking of polymer blend membranes con-taining a reactive additive using a variety of energysources.
The impacts of crosslinking on the physicaland transport properties are measured and reported. For the study reported here, polyetherimide trade-name Ultem was chosen as the primary membranecomponent. The polymer was crosslinked by blend-ing with an ethynyl-terminated monomer ETM.
Thethermosetting ETM can be crosslinked to providematerials with improved solvent resistance withoutevolution of volatile products and in the absence ofcatalysts . The thermal curing behavior and resultant prop-erties of Ultem blends with low molecular weightethynyl-terminated oligomers ETO have been re-ported.
In a study on the phase behavior and networkformation of an ethynyl-terminated polyisoimide Thermid IP blended with Ultem, Merceret al. The blends could be thermally crosslinkedat approximately C yielding tough, flexible filmswith improved solvent resistance and high-temperaturemechanical properties .
Blending of ethynyl-terminated monomers andoligomers with polyimides can influence the gastransport properties, but this is less well documented.
Rezac and Schberlformed homogeneous films from a blend of a lowmolecular weight ethynyl-terminated monomer withUltem .
These blends remained homogeneousafter thermal treatment and showed increased chem-ical and thermal stability coupled with minimalchanges to the gas transport behavior. Various energy sources have been employed topromote crosslinking in polymeric materials includ-ing thermal annealing [7,9], UV- [10,11], - ,and electron-beam-irradiation .
The thermal pro-cess activates reactive groups uniformly throughoutthe material. In contrast, the radiative processes canactivate reactive groups primarily restricted to theincident surface layer, depending on dosage rate andexposure time.An RO membrane is composed of three layers: a bottom layer made of unwoven polyester cloth of thickness – μm to support the entire membrane, a middle layer consisting of polysulfone (PSF) or polyethersulfone (PES) of thickness 30–50 μm, and a top layer of polyamide (PA) or polyetherimide (PEI), supported by PSF or PES, of average.
Journal of Membrane Science () 1–11 Influence of crosslinking technique on the physical and transport properties of ethynyl-terminated monomer/polyetherimide asymmetric.
C08G73/10 — Polyimides; Polyester-imides; Polyamide-imides; Solid-state covalent cross-linking of polyimide membranes for carbon dioxide plasticization reduction: USB2 (en) Ultrathin polyetherimide membrane and gas separation process USB1 (en).
Composite membranes with ultra-thin polymeric interpenetration network and enhanced separation performance approaching ceramic membranes for biofuel Dual-layer hollow carbon fiber membranes for gas separation consisting of carbon and mixed matrix layers Investigation of the fundamental differences between polyamide-imide (PAI) and.
carbon membranes from polyamideimide and polyetherimide for nitrogen and methane separation and its own parameter study ABSTRACT Carbon membranes well prepared from polyamideimide and polyetherimide had been studied to determine the effects of diverse parameters on membrane qualities.
Index of Materials - P.
Carbon steel is typically composed of % to about % carbon measured by weight, along with iron and trace amounts of other elements. Torlon® PAI is a family of polyamide-imides that combines the exceptional performance of thermoset polyimides with the melt-processing advantage of thermoplastics. (PEI) (polyetherimide) is a high. In this study, four different membranes were fabricated by using polyetherimide and polyacrylonitrile polymers, N-methylpyrrolidone and polyvinylpyrrolidone (PVP) via phase inversion method to improve the membrane performance in fruit juice wastewater (FJWW) treatment. A static dissipative polyetherimide utilizing proprietary filler technology which renders this material electrically conductive. This technology allows for good dimensional stability after machining (unlike conventional carbon fibers), consistent electrical properties, excellent .
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