The rheology of Torlon® solutions and its role in the formation of ultra-thin defect-free Torlon® hollow fiber membranes for gas separation

Peng, Na; Chung, Tai‐Shung; Lai, Juin‐Yih

doi:10.1016/j.memsci.2008.10.038

Cited by 42 publications

(19 citation statements)

References 36 publications

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“…It is believed that the nodular structure arises from rapid demixing of the polymer solution, followed by rapid vitrification. 45,55,56 Since the Torlon V R /NMP spinning solutions exhibits shear-thinning and strain-thinning rheological behavior, 30 it can be concluded that Torlon V R molecular chains will stretch, disentangle, and slide over one another during spinning at high elongational draw ratios. The disentangled and aligned polymer chains may result in smaller nodule sizes because of shorter-range interactions with R a , mean roughness; R ms , root mean square of Z values; R max , maximum vertical distance between the highest and lowest data points.…”

Section: Resultsmentioning

confidence: 99%

“…Only recently has Torlon V R been applied in the membrane field, in areas such as vapor permeation, 25 pervaporation, 24,26,27 and gas separation. [28][29][30] Although Torlon V R has also been utilized to fabricate NF membranes, it has only served as the supporting layer in flat-sheet membranes. 31 The uniqueness of our work is in that wholly integral Torlon V R PAI NF membranes are fabricated from a polymer/solvent binary system in the absence of additives by a one-step phase-inversion process without further modification.…”

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confidence: 99%

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Polyamide‐imide nanofiltration hollow fiber membranes with elongation‐induced nano‐pore evolution

et al. 2009

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in Wiley InterScience (www.interscience.wiley.com).The molecular design of nanoporous membranes with desired morphology and selectivity has attracted significant interest over the past few decades. A major problem in their applications is the trade-off between sieving property and permeability. Here, we report the discovery of elongation-induced nano-pore evolution during the external stretching of a novel polyamide-imide nanofiltration hollow fiber membrane in a dry-jet wet-spinning process that simultaneously leads to a decreased pore size but increased pure water permeability. The molecular weight cutoff, pore size, and pore size distribution were finely tuned using this approach. AFM and polarized FTIR verified the nano-pore morphological evolution and an enhanced molecular orientation in the surface skin layer. The resultant nanofiltration membranes exhibit highly effective fractionation of the monovalent and divalent ions of NaCl/ Na 2 SO 4 binary salt solutions. More than 99.5% glutathione can be rejected by the nanofiltration membranes at neutral pH, offering the feasibility of recovering this tripeptide.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Polyamide‐imide nanofiltration hollow fiber membranes with elongation‐induced nano‐pore evolution

et al. 2009

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“…Since the thickness of the dense-selective layer is usually lower than several hundred nanometers, [42][43][44] the dimension of nanoparticles must be much smaller than this number to avoid defects and particle penetration. Since the thickness of the dense-selective layer is usually lower than several hundred nanometers, [42][43][44] the dimension of nanoparticles must be much smaller than this number to avoid defects and particle penetration.…”

Section: As-synthesized Zif-8 Particle Propertiesmentioning

confidence: 99%

Symmetric and Asymmetric Zeolitic Imidazolate Frameworks (ZIFs)/Polybenzimidazole (PBI) Nanocomposite Membranes for Hydrogen Purification at High Temperatures

Yang¹,

Shi²,

Chung³

2012

Advanced Energy Materials

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High‐performance zeolitic imidazolate frameworks (ZIFs)/polybenzimidazole (PBI) nanocomposites are molecularly designed for hydrogen separation at high temperatures, and demonstrate it in a useful configuration as dual‐layer hollow fibers for the first time. By incorporating as‐synthesized nanoporous ZIF‐8 nanoparticles into the high thermal stability but extremely low permeability polybenzimidazole (PBI), the resultant mixed matrix membranes show an impressive enhancement in H2 permeability as high as a hundred times without any significant deduction in H2/CO2 selectivity. The 30/70 ZIF‐8/PBI dense membrane has a H2 permeability of 105.4 Barrer and a H2/CO2 selectivity of 12.3. This performance is far superior to ZIF‐7/PBI membranes and is the best ever reported data for H2‐selective polymeric materials in the literature. Meanwhile, defect‐free ZIF‐8‐PBI/Matrimid dual‐layer hollow fibers are successfully fabricated, without post‐annealing and coating, by optimizing ZIF‐8 nanoparticle loadings, spinning conditions, and solvent‐exchange procedures. Two types of hollow fibers targeted at either high H2/CO2 selectivity or high H2 permeance are developed: i) PZM10‐I B fibers with a medium H2 permeance of 64.5 GPU (2.16 ×10−8 mol m−2 s−1 Pa−1) at 180°C and a high H2/CO2 selectivity of 12.3, and, ii) PZM33‐I B fibers with a high H2 permeance of 202 GPU (6.77 ×10−8 mol m−2 s−1 Pa−1) at 180°C and a medium H2/CO2 selectivity of 7.7. This work not only molecularly designs novel nanocomposite materials for harsh industrial applications, such as syngas and hydrogen production, but also, for the first time, synergistically combines the strengths of both ZIF‐8 and PBI for energy‐related applications.

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“…In this study, Torlon®, a polyamide‐imide, was chosen as a candidate OSRO membrane material because it has superior mechanical, thermal, and chemical stability . Torlon® has been applied for membrane applications such as vapor permeation, pervaporation, and gas separations . Here, we investigate the applicability of Torlon® to realize OSRO‐type separations of similarly‐sized molecules relevant to the hydrocarbon processing industry.…”

Section: Introductionmentioning

confidence: 99%

Torlon® hollow fiber membranes for organic solvent reverse osmosis separation of complex aromatic hydrocarbon mixtures

Jang

Johnson

et al. 2019

AIChE Journal

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Defect‐free polyamide‐imide (Torlon®) hollow fiber membranes were fabricated to investigate the potential for polymer‐based organic solvent reverse osmosis (OSRO) separations. The quality of the membranes was assessed by gas permeation, and the membranes were found to be defect‐free. Low molecular weight cut‐offs of ~180 g/mol were obtained using a complex mixture of aromatic hydrocarbons relevant to refinery separations. We demonstrate bulk OSRO‐type separations of 80/20 (mol%) mixtures of toluene and 1,3,5‐triisopropylbenzene (TIPB, 204 g/mol). At an upstream pressure of 80–90 bar, we find that the permeate concentration was approximately 98.5–99.0 mol% toluene and that the TIPB rejection coefficient was approximately 90% in the permeate. We observed low solvent permeances of 0.01 L/m2 hr bar, which can be attributed to the low OSRO driving forces and the low permeability of Torlon®. The membranes were found to provide stable performance up to pressures of 95 bar and temperatures of 60°C.

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The rheology of Torlon® solutions and its role in the formation of ultra-thin defect-free Torlon® hollow fiber membranes for gas separation

Cited by 42 publications

References 36 publications

Polyamide‐imide nanofiltration hollow fiber membranes with elongation‐induced nano‐pore evolution

Polyamide‐imide nanofiltration hollow fiber membranes with elongation‐induced nano‐pore evolution

Symmetric and Asymmetric Zeolitic Imidazolate Frameworks (ZIFs)/Polybenzimidazole (PBI) Nanocomposite Membranes for Hydrogen Purification at High Temperatures

Torlon® hollow fiber membranes for organic solvent reverse osmosis separation of complex aromatic hydrocarbon mixtures

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