Polyimides Matrimid

Kharitonov et al. [59] have shown that direct fluorination of the polyimide Matrimid is possible, hence the resulting membrane should have a nice potential for use in harsh environment. Perfluorinated materials were also studied by Hagg [60] for chlorine gas purification, and were shown to be exceptionally stable in these harsh environments. The selectivity was however too low. In a later publication on chlorine purification [31] it was suggested to use perfluorinated monomers as surface-modifying compounds for pore tailoring of glass membranes for chlorine gas separation. 

Kharitonov AP, Moskvin YL, Syrtsova DA, Starov VM, and Teplyakov VV. Direct fluorination of the polyimide Matrimid 5218 The formation Kinetics and Physicochemical properties of the Fluorinated layers. J. Appl. Pol. Sci. 2004 92 6-17. 

Analytical pyrolysis has been successfully used for monitoring the curing process of certain polyimide polymers. For example, the polyimide Matrimid 5292 is obtained from two components in a reaction as shown below ... 

Jiang, L.Y., Chung, T.-S. and Rajagopalan, R. 2008. Dehydration of alcohols by pervapora-tion through polyimide Matrimid asymmetric hollow fibers with various modifications. Chenh ng Sa. 63 204-216. 

Although CA is the focus of this study, there are other polymers available of which the most widely reported are the polyimides [22]. Reported values of even 100 for CO2/CH4 separation factors (a) are not nncommon with polyimides. This compares with reported pure gas dense film CA a valnes listed in Table 15.2 of about 32 depending on the acetyl content [23]. The higher acetyl content polymers have higher CO2 permeabihty. A commercially available polyimide, Matrimid, has attracted much interest and had a pure gas a reported between 43 and 58 depending on how the membrane was prepared and tested [24]. Chemical structures of these two polymers are illustrated in Figure 15.4. 

Introducing a thermoplastic resin [53,54] into the matrix such as a thermoplastic polyimide Matrimid 5218 [55,56], polyethersidfone [54-57], polyetherimide [55-56,58-61] and poly (arylene ether) [58-59,61-63]. All these polymers however, cause an attendant loss of processability coupled with poorer solvent resistance. 

In EP07708077A3 (Dabou et al. 1996), gas separation polymer membranes were prepared from mixtures of a polysulfone, Udel P-1700 and an aromatic polyimide, Matrimid 5218. The two polymers were proven to be completely miscible as confirmed by optical microscopy, glass transition temperature values and spectroscopy analysis of the prepared mixtures. This complete miscibility allowed for the preparation of both symmetric and asymmetric blend membranes in any proportion from 1 to 99 wt% of polysulfone and polyimide. The blend membranes showed significant permeability improvements, compared to the pure polyimides, with a minor change in the selectivity. Blend membranes were also considerably more resistant to plasticization compared with pure polyimides. This work showed the use of polysulfone-polyimide polymer blends for the preparation of gas separation membranes for applications in the separation of industrial gases. 

A commercially available polyimide, Matrimid 5218, exhibits a combination of selectivity and permeability for industrially significant gas pairs superior to that of most other readily available polymers. Its permeation properties, combined with its processability (i.e., solubility in common solvents) makes it an ideal candidate for gas separation applications. 

Figure 9.17 illustrates the general schematic of the membrane unit used in permeation measurements. Experimental permeation runs were performed with CO2 and N2 in a composite PES/PI (polyethersulfone Sumikaexcel/polyimide Matrimid 5218) hollow-fiber membrane. The single-component permeances were measured using a standard variable-pressure method and the binary ratios converted into the corresponding ideal selectivities. A specified feed pressure was applied to the upstream shell-side, while the permeate side was initially under vacuum. The permeation rates were calculated from the pressure increase as a function of time, in a downstream calibrated volume. The permeation stopped when equalization between pressures on both sides of the membrane was achieved. The main physical properties of the membrane are listed in Table 9.2. 

A common problem in the fabrication of supported carbon membranes is related to cracks formation and the minimization of defects arising from pyrolysis. Figure 10.6 shows a supported carbon membrane obtained from a commercial polyimide Matrimid coated on a porous substrate after pyrolyz-ing at 973 K with a ramp rate of 2.5 K/min in Nj atmosphere. The differences of thermal expansion coefficients between substrate and coated polymer film during pyrolysis created a lot of cracks in the resultant carbon membrane. Therefore, the selection of polymer precursor, the optimization of pyrolysis temperature and the deposition parameters of the polymer layer are believed to be very important for avoiding such cracks. 

Specialty polymers Aerospace composites Primaset BADCY, PT-resins Matrimid Kapton Avimid 2,2-Bis(4-cyanatophenyl) propane and oligomers, Novolac cyanates Nonmelting polyimides Lonza, Switzerland Ffuntsman, USA DuPont, USA Mitsui, Japan... 

COMPIMIDE 796-COMPIMIDE 123. b Resisttherm PH-10 polyhydantoin. c Resistofol N polyhydantoin. d Matrimide 5218 polyimide. 

The first, and currently only, successful solvent-permeable hyperfiltration membrane is the Starmem series of solvent-resistant membranes developed by W.R. Grace [40]. These are asymmetric polyimide phase-inversion membranes prepared from Matrimid (Ciba-Geigy) and related materials. The Matrimid polyimide structure is extremely rigid with a Tg of 305 °C and the polymer remains glassy and unswollen even in aggressive solvents. These membranes found their first large-scale commercial use in Mobil Oil s processes to separate lube oil from methyl ethyl ketone-toluene solvent mixtures [41-43], Scarpello et al. [44] have also achieved rejections of >99 % when using these membranes to separate dissolved phase transfer catalysts (MW 600) from tetrahydrofuran and ethyl acetate solutions. 

MATRIMID CIBA-Geigy Indane containing polyimide... 

A similar concept based on a mixture of BMI-MDA (Matrimide 5292 A) and bis-alkenylphenol (Matrimide 5292 B) with a flexible polyimide has been patented as a heat-resistant adhesive [117]. 

A further point of interest is the effect, if any, of the addition and elimination of amine on the molecular weight of the polyimide. An interesting experiment was devised to investigate this possibility. Samples of Matrimid 5218 were reacted in separate experiments with... 

Matrimid . [Qba-Geigy/Plastics] Thermoplastic polyimides for structural composites and adhesives. 

Matrimid 5218. See Polyimide, thermoplastic Matrimid 5292A. See Bismaleimide Matrimid 5292B. See 0,0 -D allyl bisphenol A Mattex . See Kaolin, calcined Matting acid. See Sulfuric acid Matting Microblanc. See Calcium monocarbonate Maw oil. See Poppyseed oil Maxahibit lOCt, Maxahibit TT-50. See Sodium tolyltri azole... 

Wang Y, Gob SH, Chung TS. Miscibility study of torlon(r) polyamide-imide with matrimid(r) 5218 polyimide and polybenzimidazole. Polymer 2007 48(10) 2901-9. 

The influence of H2S on the CO2 permeability in the glassy polymeric membranes polysulfone and Matrimid 5218 (a polyimide) are shown in Figures 11.6 and 11.7 respectively, where the membrane was exposed to 90% N2-10% CO2 gas mixture with H2S at 500ppm. 

---