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Characteristics of PVDF Membranes Irradiated by Electron Beam.

Jaleh B, Gavary N, Fakhri P, Muensit N, Taheri SM - Membranes (Basel) (2015)

Bottom Line: The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement.The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity.Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Bu-Ali Sina University, Hamedan 65174, Iran. jaleh@basu.ac.ir.

ABSTRACT
Polyvinylidene fluoride (PVDF) membranes were exposed vertically to a high energy electron beam (EB) in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphologies were studied by Scanning Electron Microscopy (SEM) and showed some changes in the pore size. Thermogravimetric (TGA) analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR) showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane.

No MeSH data available.


Electron paramagnetic resonance (EPR) curve of irradiated PVDF membrane by 50 kGy, 200 kGy and 300 kGy.
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membranes-05-00001-f004: Electron paramagnetic resonance (EPR) curve of irradiated PVDF membrane by 50 kGy, 200 kGy and 300 kGy.

Mentions: The formation of free radicals was detected by EPR measurements. Free radicals induced in PVDF by ionizing radiation have been previously studied. EB irradiation of PVDF leads to a scission of C-H, C-F, and C=C bonds and creation of –˙CF2 , –˙CH2 , –CF2–˙CH–CF2– and –CH2–˙CF–CH2– radicals. Some of the radicals become oxygenated in the air and alkoxy or alkyl peroxy radicals appear [10,17]. The radical amount is proportional to the absorbed dose. Figure 4 shows changes in the EPR spectra of PVDF after irradiation with various doses. From the Figure it can be seen that the intensity of the peaks increases with increasing dose. This confirms the increasing number of free radicals at higher doses. Also, a peak appears around 3480 G above 150 kGy, this peak is probably related to peroxide radicals [17].


Characteristics of PVDF Membranes Irradiated by Electron Beam.

Jaleh B, Gavary N, Fakhri P, Muensit N, Taheri SM - Membranes (Basel) (2015)

Electron paramagnetic resonance (EPR) curve of irradiated PVDF membrane by 50 kGy, 200 kGy and 300 kGy.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384087&req=5

membranes-05-00001-f004: Electron paramagnetic resonance (EPR) curve of irradiated PVDF membrane by 50 kGy, 200 kGy and 300 kGy.
Mentions: The formation of free radicals was detected by EPR measurements. Free radicals induced in PVDF by ionizing radiation have been previously studied. EB irradiation of PVDF leads to a scission of C-H, C-F, and C=C bonds and creation of –˙CF2 , –˙CH2 , –CF2–˙CH–CF2– and –CH2–˙CF–CH2– radicals. Some of the radicals become oxygenated in the air and alkoxy or alkyl peroxy radicals appear [10,17]. The radical amount is proportional to the absorbed dose. Figure 4 shows changes in the EPR spectra of PVDF after irradiation with various doses. From the Figure it can be seen that the intensity of the peaks increases with increasing dose. This confirms the increasing number of free radicals at higher doses. Also, a peak appears around 3480 G above 150 kGy, this peak is probably related to peroxide radicals [17].

Bottom Line: The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement.The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity.Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Bu-Ali Sina University, Hamedan 65174, Iran. jaleh@basu.ac.ir.

ABSTRACT
Polyvinylidene fluoride (PVDF) membranes were exposed vertically to a high energy electron beam (EB) in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphologies were studied by Scanning Electron Microscopy (SEM) and showed some changes in the pore size. Thermogravimetric (TGA) analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR) showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane.

No MeSH data available.