Gas permeation properties of cardo polyaryletherketones containing different alkyl substituents

The gas permeation properties of a series of cardo polyaryletherketone materials are reported, In this series, the hydrogen atoms of benzene rings on the backbone are systematically replaced with different alkyl substituents. The effects of temperature and structure variation on gas permeability and selectivity are discussed in detail. The experimental results revealed that the polyetherketone obtained by the introduction of dimethyl and diisopropyl substituents to phenolphthalein unit is 3 similar to 6 times more permeable than the unmodified one for the gases studied.

Sulfonation of polyetheretherketone and its effects on permeation behavior to nitrogen and water vapor

The novel polyetheretherketone (PEK-C) prepared from phenolphthalein in our institute is an amorphous, rigid, tough material with good mechanical properties over a wide temperature range. To improve its water vapor permeability for the application of gas drying, PEK-C was sulfonated with concentrated sulfuric acid and transferred in sodium, cupric, and ferric salt forms. Sulfonation degree can be regulated by controlling the temperature and reaction time. Characterization of sulfonated PEK-C in sodium form was made by infrared spectroscopy. Some properties of the sulfonated PEK-C, such as solubility, glass transition temperature, thermal stability, mechanical properties, and transport properties to nitrogen and water vapor, are also discussed. (C) 1996 John Wiley & Sons, Inc.

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF GASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .3. SORPTION BEHAVIOR OF WATER-VAPOR IN PPO AND SULFONATED PPO MEMBRANES

Water vapor absorption and desorption by poly (phenylene oxide) (PPO) and sulfonated PPO (SPPO) membranes were studied at a constant temperature of 30-degrees-C and over a broad range of water activity (0.05 less-than-or-equal-to a < 0.8) by the weighing

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .1. SULFONATION OF PPO AND CHARACTERIZATION OF THE PRODUCTS

Poly(2,6-dimethylphenylene oxide) (PPO) was sulfonated to varying degrees using different sulfonating agents. Physical properties such as solubility, density, and thermal properties were studied for both PPO and sulfonated PPO (SPPO) with different degree

STUDIES ON THE SULFONATION OF POLY(PHENYLENE OXIDE) (PPO) AND PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES .2. PERMEATION BEHAVIOR OF CASES AND WATER-VAPOR THROUGH SULFONATED PPO MEMBRANES

The permeation behaviors of water vapor and gases were studied for both PPO and SPPO of different sulfonation degree. It was found that the permeability of water vapor increased, and those of oxygen and nitrogen decreased; thus the selectivity for water v

Effect of H2S on stress corrosion cracking and hydrogen permeation behaviour of X56 grade steel in atmospheric environment

Susceptibility to stress corrosion cracking of X56 steel and its relationship with hydrogen permeation behaviour in atmospheric environment containing H2S was investigated by hydrogen permeation tests at a slow strain rate. The results show that: the fracture strain decreases with the decrease of strain rate under the same experimental conditions; the fracture strain also decreases with the increase of H2S concentration under the same strain rate, and the increased concentration of H2S has no significant effect on the hydrogen permeation in the first wet, etc. dry cycle, however has lead to increased hydrogen permeation in the later cycles. The SEM images of the fractured surfaces show clear evidences of enhanced stress corrosion cracking susceptibility by H2S.

Effect of mechanical deformation on permeation of hydrogen in iron

Rate of hydrogen permeation was measured under static as well as dynamic mechanical deformation conditions, Cylindrical tensile test specimens were used for the study and hydrogen permeation was measured electrochemically, It was observed that the hydrogen diffusivity decreased as plastic deformation increased for the static deformation experiments while elastic deformation had no significant effect on diffusivity but increased the steady state permeation flux, For the dynamic loading experiment, an elastic deformation increased the hydrogen permeation rate almost linearly. Onset of plastic deformation led a sudden decrease of permeation rate and the reduced rate was rapidly recovered when the plastic deformation ceased. These rapid changes in the permeation rates were explained that the absorbed hydrogen was trapped by dislocations and creation rate and density of dislocations changed drastically when plastic deformation started and stopped.

Hydrogen permeation and corrosion behaviour of high strength steel 35CrMo under cyclic wet-dry conditions

Hydrogen permeation behaviours of high strength steel 35CrMo under different cyclic wet-dry conditions have been investigated by using Devanathan-Stachurski's technique. Four electrolytes were used: distilled water, seawater, seawater containing 1500 ppm H2S and seawater containing 0.03 mol L-1 SO2. The corrosion weight loss of 35CrMo in the wet-dry cycles was measured simultaneously. The experimental results show that hydrogen can be detected at the surface opposite to the corroding side of the specimen during wet-dry cycles and the permeation current density during a wet-dry cycle showed a maximum during the drying process. The hydrogen permeation was obviously promoted by Cl- ions, H2S and SO2. The hydrogen permeation in the real marine atmosphere has also been investigated. There is a clear correlation between the amount of hydrogen permeated and the corrosion weight losses. Results show the importance of hydrogen permeation that merits further investigation.

Hydrogen permeation behavior and corrosion monitoring atmospheric of steel in cyclic wet-dry environment

Hydrogen permeation of 16Mn steel under a cyclic wet-dry condition was investigated by Devanathan-Stachurski's electrolytic cell with a membrane covered on the exit side by a nickel layer and the weight loss was measured for each wet-dry cycle. The results show that hydrogen permeation current change with different atmospheric environment: distilled water, seawater, and seawater containing 100 ppm H2S. The results show that seawater can induce an increase in the hydrogen permeation current due to the hydrolyzation reaction. And after the increase, equilibrium is reached due to the equilibrium of hydrolyzation reaction effect and the block of the rust layer. On the other hand, H2S contamination also can induce an increase in the maximum hydrogen permeation current due to the hydrolyzation reaction. And H2S contamination delays the time that hydrogen permeation is detected because of the formation of the FeS(1-x) film. The FeS(1-x) film can block the absorption of hydrogen onto the specimen surface. The surface potential change and the pH change of the metal surface control the hydrogen permeation current. And a clear linear correlation exists between the quantities of hydrogen permeated through the 16Mn steel and the weight loss. Based on the linear correlation, we monitored the corrosion rate by monitoring the hydrogen permeation current by a sensor outside. Good coherences were shown between results in laboratory and outside.

The hydrogen permeation investigation of API X56 steel in sea mud

It was found that the corrosion rate of steel in the sea mud with sulfate-reducing bacteria (SRB) could be as high as 10 times of that in the sea mud without SRB. And the hydrogen permeation reaction would occur when metals were corroded. So it is necessary to investigate the effect of living SRB on hydrogen permeation in the sea mud. Cathodic potential was often added to metals in order to protect them. But hydrogen permeation could be affected by the cathodic potential. So it is also necessary to study the effect of cathodic potential on hydrogen permeation. In this paper, the hydrogen permeation actions of APT X56 steel in the sea mud with and without SRB at corrosion and cathodic potential were studied with an improved Devanathan-Stachurski's electrolytic cell. Experimental results showed that during the growth of SRB, the current density curve of hydrogen permeation was accordant with the growth curve of SRB. But the hydrogen permeation current density of APT X56 steel hardly changed in the sterilized sea mud. Compared with the hydrogen permeation current density of APT X56 steel in the sterilized sea mud, the hydrogen permeation of APT X56 steel in the sea mud could be accelerated by living SRB. Experimental results also showed that the hydrogen permeation current density increased rapidly when the cathodic potential was added to the three-electrode system of the cathodic cell, and then the hydrogen permeation current density could obtain a stable value slowly. So the cathodic potential added to the cathodic cell could accelerate hydrogen permeation.

Synthesis and gas permeation properties of an NaA zeolite membrane

A high quality NaA zeolite membrane, which shows a H-2/n-C4H10 permselectivity of 106, has been synthesized on a seeded alpha-Al2O3 support by a multistage synthesis method.