Stability and degradation of poly(naphthoyleneimidobenzimidazole)

Lavrenko, P. N.; Pogodina, N.V.; Пономарев, И. И.; Okatova, O. V.; Evlampieva, N. P.

doi:10.1016/0141-3910(94)90009-4

Cited by 4 publications

(5 citation statements)

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“…There is limited information on the effect of degradation on nylon fiber properties. However, Lavrenko et al studied the stability of poly(naphthoyleneimidobenzimidazole) (PNIB) fiber under atmospheric conditions and showed that the material experienced slow hydrolytic degradation of the macromolecules, leading to a drop in the intrinsic viscosity and changes in mechanical properties such as tensile strength and elastic modulus. They also showed that the decrease in molecular weight is significantly accelerated for PNIB in the powered state.…”

Section: Resultsmentioning

confidence: 99%

“…From the results of Joung et al, the time variation of the gas holdup in nylon fiber suspensions is influenced by the change in nylon fiber deformation during an experiment, leading to a change in the suspension viscosity. According to Lavrenko et al, fiber degradation affects fiber properties such as elastic modulus, which, in turn, affects fiber deformation. Nylon fiber deformation would continue to change during exposure in a hydrodynamic field, leading to an increase in the gas holdup with time.…”

Section: Resultsmentioning

confidence: 99%

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Gas Holdup Behavior in Nylon Fiber Suspensions

Heindel

2004

Ind. Eng. Chem. Res.

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The gas holdup behavior in a nylon fiber suspension with various fiber lengths (L = 2, 3, and 6 mm) is investigated. Experiments are performed over a range of superficial gas velocities (Ug≤ 18 cm/s) and a range of fiber mass fractions (0 ≤ C ≤ 1.8%) in a 15.24-cm-diameter semibatch bubble column. Day-to-day variations in the gas holdup create difficulties in interpreting the effect of the fiber mass fraction. These variations are attributed primarily to nylon fiber surface additives leaching into the suspension water and loss of hydrophobicity in a prolonged water environment. As an alternative, the gas holdup in rayon fiber suspensions is highly reproducible. The gas holdup behavior in a nylon fiber suspension with various fiber lengths (L ) 2, 3, and 6 mm) is investigated. Experiments are performed over a range of superficial gas velocities (U g e 18 cm/s) and a range of fiber mass fractions (0 e C e 1.8%) in a 15.24-cm-diameter semibatch bubble column. Day-to-day variations in the gas holdup create difficulties in interpreting the effect of the fiber mass fraction. These variations are attributed primarily to nylon fiber surface additives leaching into the suspension water and loss of hydrophobicity in a prolonged water environment. As an alternative, the gas holdup in rayon fiber suspensions is highly reproducible.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Gas Holdup Behavior in Nylon Fiber Suspensions

Heindel

2004

Ind. Eng. Chem. Res.

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“…The open circuit voltage (OCV) of the cell under testing did not change significantly in the course of 5000 h, indicating sufficient hydrolytic stability and low gas crossover through the membrane [ 4 ]. The main problem concerning the use of co-SPNIs and classical PNI polymers in fuel cell applications is that all polyimides are known to be sensitive to hydrolysis [ 10 , 14 , 15 , 16 ]. The introduction of sulfonate groups along the polymer chains increases the overall hydrophilicity and, consequently, the rate of water diffusion within the structure, which contributes to the hydrolytic process.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Study of Sulfonated Co-Polynaphthoyleneimide Proton-Exchange Membrane for a H2/Air Fuel Cell

et al. 2020

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The sulfonated polynaphthoyleneimide polymer (co-PNIS70/30) was prepared by copolymerization of 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODAS) and 4,4’-methylenebisanthranilic acid (MDAC) with ODAS/MDAC molar ratio 0.7/0.3. High molecular weight co-PNIS70/30 polymers were synthesized either in phenol or in DMSO by catalytic polyheterocyclization in the presence of benzoic acid and triethylamine. The titration reveals the ion-exchange capacity of the polymer equal to 2.13 meq/g. The membrane films were prepared by casting polymer solution. Conductivities of the polymer films were determined using both in- and through-plane geometries and reached ~96 and ~60 mS/cm, respectively. The anisotropy of the conductivity is ascribed to high hydration of the surface layer compared to the bulk. SFG NMR diffusometry shows that, in the temperature range from 213 to 353 K, the 1H self-diffusion coefficient of the co-PNIS70/30 membrane is about one third of the diffusion coefficient of Nafion® at the same humidity. However, temperature dependences of proton conductivities of Nafion® and of co-PNIS70/30 membranes are nearly identical. Membrane–electrode assemblies (MEAs) based on co-PNIS70/30 were fabricated by different procedures. The optimal MEAs with co-PNIS70/30 membranes are characterized by maximum output power of ~370 mW/cm2 at 80 °C. It allows considering sulfonated co-PNIS70/30 polynaphthoyleneimides membrane attractive for practical applications.

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“…There is limited information on the effect of degradation on Nylon fiber properties. However, Lavrenko et al (1994) studied the stability of poly (napthoyleneimidobenzimidazole) (PNIB) fiber under atmospheric conditions and showed that the material experienced slow hydrolytic degradation of the macromolecules, leading to a drop in intrinsic viscosity and changes in mechanical properties such as tensile strength and elastic modulus. They also showed that the decrease in molecular weight is significantly accelerated for PNIB in the powered state.…”

Section: Mechanism 2: Nylon Fiber Degradationmentioning

confidence: 99%

“…From the results of Joung et al (2002), the time variation of gas holdup in Nylon fiber suspensions is influenced by the change in Nylon fiber deformation during an experiment, leading to a change in suspension viscosity. According to Lavrenko et al (1994), fiber degradation affects fiber properties like elastic modulus, which, in turn, affects fiber deformation. Nylon fiber deformation would continue to change during exposure in a hydrodynamic field, leading to an increase in gas holdup with time.…”

Section: Mechanism 4: Nylon Fiber Shape Deformationmentioning

confidence: 99%

Gas holdup in a gas-liquid-fiber semi-batch bubble column

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Stability and degradation of poly(naphthoyleneimidobenzimidazole)

Cited by 4 publications

References 1 publication

Gas Holdup Behavior in Nylon Fiber Suspensions

Gas Holdup Behavior in Nylon Fiber Suspensions

Preparation and Study of Sulfonated Co-Polynaphthoyleneimide Proton-Exchange Membrane for a H2/Air Fuel Cell

Gas holdup in a gas-liquid-fiber semi-batch bubble column

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