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Influence of the Isothermal Annealing on the Free Volume Changes in Thermo-Shrunken Polyethylene by Positron Annihilation

100%
Osoba W.
Acta Physica Polonica A
|
2001
|
vol. 99
|
issue 3-4
447-454
EN
Positron lifetime measurements in polyethylene have been performed. Samples of the polyethylene were isothermally annealed at three temperatures (373 K, 423 K, and 473 K) for different time periods (from 5 min to 5 h). After cooling, the samples were used for the lifetime measurements in air at room temperature. A conventional fast-slow coincidence lifetime spectrometer with plastic scintillators has been used to perform the lifetime measurements. Mean free volumes radii and fractional free volume have been calculated from the lifetime data.
2
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Investigation of the Free Volume Changes in Thermally Treated Polyethylene by Positron Annihilation

100%
Osoba W.
|
|
vol. 95
|
issue 4
632-636
EN
Positron lifetimes measurements in polyethylene were performed. Samples of the polyethylene were heated in the temperature range from 320 to 570 K. After cooling, the samples were used for the lifetime measurements in air at room temperature. A conventional fast-slow coincidence lifetime spectrometer was used for the measurements. Mean free volumes radii were calculated from the lifetime data.
3
Content available remote

Free Volume in Plastified Poly(Vinyl Chlorate)

63%
Borek J., Osoba W.
Acta Physica Polonica A
|
1995
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vol. 88
|
issue 1
91-95
EN
Positron lifetimes measurements in pure poly(vinyl chlorate) (PVC) and in plastified PVC were performed. Three different plasticizers were used: dibutyl phtalate, dioctyl phtalate and tricresyl phosphate. The measured samples were prepared of PVC with two different plasticizers concentration (20% and 30% of the plasticizers in the poly(vinyl chlorate)). All the measurements were performed in air at room temperature. A conventional fast-slow coincidence lifetime spectrometer was used for the measurements. Free volume radii were calculated from the lifetime data.
4
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Investigation of the Temperature Dependence of Free Volume in Polymethylpentene by Positron Annihilation Method

63%
Danch A., Osoba W.
Acta Physica Polonica A
|
2005
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vol. 107
|
issue 5
811-816
EN
Positron lifetime measurements in polymethylpentene were performed in a wide temperature range. A conventional fast-slow coincidence lifetime spectrometer with plastic scintillators was used. All the measurements were made in vacuum. Additional measurements (X-ray diffraction, differential scanning calorimetry, and mechanical spectroscopy) were also performed to establish properties of samples. Mean free volume radii in the investigated samples were estimated from the positron lifetimes measurements results. An increase in I_3 with the elapsed time of measurements was observed.
5
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Influence of Temperature and Pressure on the Free Volume in Thermo-Shrunken Polyethylene by Positron Annihilation

51%
Danch A., Osoba W., Wawryszczuk J.
Acta Physica Polonica A
|
2008
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vol. 113
|
issue 5
1307-1313
EN
Positron lifetime measurements were performed as a function of temperature and pressure for thermo-shrunken polyethylene. Mean volume of free volume cavities in the investigated polymer was estimated from the results of the measurements. This mean volume turned out to be the smooth function of temperature (from room temperature to 8.5 K) and high pressure (from 0.1 MPa to about 500 MPa). The effect of trapping of the free electrons produced during positron irradiation was observed at low temperature.
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