Polyetherimide, oxygen permeability

Figure 3. Correlation between polyarylate and polyetherimide oxygen permeability versus reciprocal of specific free volume.

To further investigate the question of polymer structure-permeability relationships, this study reports oxygen permeability measurements on a group of structurally varied bisphenol based polymers. In addition to representing commercially important classes of engineering thermoplastics, polycarbonates, polyarylates and polyetherimides can be easily prepared from a common set of... 

A plot of the logarithim of the oxygen permeability coefficients versus the reciprocal of the SFVs, as proposed by Lee, shows a fair correlation between these values. Data for the polyetherimides and polyarylates (Figure 3) is meager, but does allow some general conclusions to be drawn. The model does apparently overestimate the permeability for the bisphenol A based PEI 24. In addition, the fit of the polyarylate data with the calculated model is favorable except for an overestimation of the permeability of the bis(4-hydroxy-... 

Attention has been paid to the possible use of multilayer coextrusion of engineering resins for dual ovenable containers, as multilayer packaging could increase shelf stability and thus eliminate the need for freezing or refrigeration. One multilayer combination in commercial use is a sheet of Lexan polycarbonate sandwiched between layers of Ultem polyetherimide. Thermoformed trays of this material are reported to have better break resistance at lower temperatures and higher stiffness at temperatures up to 232°C, as compared to CPET. They are also insert, compatible with polyester lidding materials, and have lower oxygen permeability than PET materials. 

The permeability coefficients of nitrogen, oxygen and toluene are 280, 600 and 1.4 10 Barrer. respectively. A composite membrane has been developed for the removal of toluene vapours from air. As sublayer a polyetherimide (PEI) membrane was developed which has been characterized by the nitrogen permeability and the bubble point (bp). Two membranes (A and B) have been developed with the following properties Membrane A = 10 cm. cm 2.s. cniHg, andar(,p = 0.5 jim... 

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