Characterization of asymmetric hollow fibre membranes with graded-density skins

Fritzsche, A. K.; Murphy, Morgan; Cruse, C. A.; Malon, R. F.; Kesting, R. E.

doi:10.1016/0950-4214(89)80020-9

Cited by 39 publications

(12 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This assemblage is similar to other prototype asymmetric composite membranes [5,6]. The polyurethane is mechanically stable, resistant to solvent, and penetrable to air, and is an efficient trap for isocyanate aerosol; whereas the backup membrane allows air to flow with a sufficient linear velocity (at least 0.5 L/min) in order to capture particles in the respirable range (up to 10 km) while remaining impermeable to solvent, derivatizing reagent, and isocyanate vapor swept from the support bed.…”

Section: Introductionmentioning

confidence: 51%

Preparation and Evaluation of Polyuretham Foam/Rubber Membrane-Based Samplers for use in Isocyanate Sampling

Rudzinski¹,

Yin²,

Anderson³

et al. 1998

Polymer-Plastics Technology and Engineering

View full text Add to dashboard Cite

In order to collect isocyanate in both aerosol and vapor forms, we have developed a dual-membrane sampler which features a moist porous bed, backed up by an impermeable membrane. A polyester-polyurethane foam (PUF) was selected to function as the porous bed, and it was evaluated for its ability to resist solvent RUDZlNSKl ET AL. degradation and swelling while permitting rapid air penetration. Natural rubber (NR) and styrene-butadience rubber (SBR) membranes were prepared to serve as backup membranes. These were also evaluated for their solvent compatibility and air-penetration characteristics. A polyester-polyurethane foam backed up by a NR membrane prepared by an efficient vulcanization procedure was selected as the best combination for development of the isocyanate sampler. Recovery studies using the hexamethylenebased polyisocyanate, biuret, indicate better than 80% recovery of polyisocyanate after application to the PUF.

show abstract

Section: Introductionmentioning

confidence: 51%

Preparation and Evaluation of Polyuretham Foam/Rubber Membrane-Based Samplers for use in Isocyanate Sampling

Rudzinski¹,

Yin²,

Anderson³

et al. 1998

Polymer-Plastics Technology and Engineering

View full text Add to dashboard Cite

show abstract

“…The morphology of the asymmetric 6FDA-BAAF membrane consisted of an ultrathin skin layer supported by a sponge-like porous substructure. The interface between the two layers appears more distinct than that of other asymmetric membranes (10)(11)(12)(13)(14)(15)(16). The thickness of the skin layer was about 60 nm and there were no finger voids in the sponge-like porous layer.…”

Section: Methodsmentioning

confidence: 97%

“…For any practical use, membranes with a thin, selective layer must be developed. In particular, thin-skinned asymmetric membranes can have high gas fluxes and mechanical strength due to their structure (10)(11)(12)(13)(14)(15)(16). However, membranes with a skin layer thickness of less than 100 nm are very difficult to prepare by conventional methods (10)(11)(12)(13)(14)(15)(16).…”

mentioning

confidence: 99%

A New Type of Asymmetric Polyimide Gas Separation Membrane Having Ultrathin Skin Layer

Hachisuka

Ohara

Ikeda

1999

ACS Symposium Series

View full text Add to dashboard Cite

A new type of asymmetric gas separation membrane having an ultrathin, essentially defect-free skin layer using diethylene glycol dimethylether (DGDE) as a dope solvent was developed. The asymmetric membrane made of 6FDA-BAAF polyimide consisted of an ultrathin skin layer supported by a sponge-like porous substructure. The skin layer was essentially defect-free and had a thickness of 40-60 nm. The formation of such ultrathin skin layer was contributed to the mixing properties of the dope solvent and water as the quench medium. Solvents such as DGDE are miscible with water; however, a sharp interface between DGDE and water forms during the initial stages of the quench step. The ultrathin skin layer was possibly formed by solidification at such interface.The preparation of membranes having a thin skin layer is one of the most significant factors to achieving high gas fluxes. In addition, the skin layer of gas separation membranes must be essentially defect-free to obtain a high selectivity. Recently, thick, isotropic films of polyimides containing 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) were reported to exhibit both higher gas selectivity and permeability than previous gas separation membrane materials (1-9). However, the gas fluxes of thick, isotropic films are far too low for industrial applications. For any practical use, membranes with a thin, selective layer must be developed. In particular, thin-skinned asymmetric membranes can have high gas fluxes and mechanical strength due to their structure (10-16). However, membranes with a skin layer thickness of less than 100 nm are very difficult to prepare by conventional methods (10-16). The preparation of a high-performance asymmetric membrane having a skin layer thickness of less than 100 nm was investigated using a new casting solution method. The formation mechanism of such asymmetric membrane was examined in terms of the interaction between the polymer, solvent,

show abstract

“…Figure 2 illustrates the chemical structure ers reported that coagulation rates and solvent of this hexafluoro-isopropylidene group-conexchange mechanisms were strongly dependent on their respective molecular sizes and solubility differences. 7,23 The bigger the molecular size is, the slower the exchange process will be. An increase in the solubility difference between dope solvents and coagulants results in an increase in coagulation rate.…”

Section: Rtmentioning

confidence: 99%

“…Significant second-generation polysulfone hollow fibers using advancement has been made in both membrane Lewis acid : base complex solvent technology. 7,8 materials and fabrication technology during the This technology has been examined, evaluated, last 15 years. Materials with better separation and expanded by Chung and his coworkers 9 at characteristics, i.e., permeability and selectivity, Hoechst Celanese (HC).…”

Section: Introductionmentioning

confidence: 99%

The effects of spinning conditions on asymmetric 6FDA/6FDAM polyimide hollow fibers for air separation

Chung

Kafchinski

1997

J. Appl. Polym. Sci.

119

View full text Add to dashboard Cite

: We have found that the chemistries of inner and external coagulants, gelation bath temperature, and air gap distance have profound effects on 6FDA-polyimde hollow-fiber morphology and performance. This 6FDA-polyimide is made of 50 mol % 2,2-bis(3,4-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA) and 50 mol % 2,2-bis(3-aminophenyl) hexafluoro propane (4,4 6F-diamine) (6FDAM). An increase in air gap distance tends to induce three-dimensional open-cell pore formation. Raising bath temperature has a similar effect. Multilayer finger-void structure can be completely eliminated if one properly chooses a bore-fluid flow rate and a gelation bath temperature. Experimental data demonstrate that the location of the dense layer can be shifted from the inner skin to the outer skin based on the chemistry (solubility parameter) of coagulants. The location of finger voids is also dependent on the chemistry of coagulants, and the dense layer location may shift from the inner surface to the external surface or appear in both surfaces dependent on the differences in solubility and coagulation rate. A defect-free 6FDA/6FDAM polyimide fiber with a selectivity of 4.73 and a permeance of 38.1 GPU is produced.

show abstract

Characterization of asymmetric hollow fibre membranes with graded-density skins

Cited by 39 publications

References 9 publications

Preparation and Evaluation of Polyuretham Foam/Rubber Membrane-Based Samplers for use in Isocyanate Sampling

Preparation and Evaluation of Polyuretham Foam/Rubber Membrane-Based Samplers for use in Isocyanate Sampling

A New Type of Asymmetric Polyimide Gas Separation Membrane Having Ultrathin Skin Layer

The effects of spinning conditions on asymmetric 6FDA/6FDAM polyimide hollow fibers for air separation

Contact Info

Product

Resources

About