Autor: He, Chunqing - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide
Autorzy:: Li, Jingjing
Yin, Chongshan
Zhou, Yawei
Li, Gang
Yeh, Jen-taut
He, Chunqing
Powiązania:: https://bibliotekanauki.pl/articles/1033920.pdf
Data publikacji:: 2017-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: Nylon12/PVA
ScCO₂
positron annihilation
free volume
relaxation
Opis:: Free volume variations of Nylon12/Polyvinyl alcohol (Nylon12/PVA) blends treated in supercritical carbon dioxide (ScCO₂) were investigated using positron annihilation lifetime spectroscopy. It is found that o-Ps lifetime τ₃ and the corresponding intensity I₃ in Nylon12/PVA decrease with increase of the PVA content. Being treated in ScCO₂ at 50°C and 20 MPa for 1 h, the free volume holes in Nylon12/PVA blends expand to different extents depending on the weight ratio of PVA. After releasing of CO₂, the free volume size decreases as a function of the elapsed time due to the molecular relaxation, and the relaxation time constant depends on the content of PVA in the blends.
Źródło:: Acta Physica Polonica A; 2017, 132, 5; 1552-1555
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Effect of Ultraviolet Absorber on Photo-Degradation of Epoxy Coating Studied by Slow Positron Beam
Autorzy:: Wang, Zheng
Liu, Fuwei
Li, Jingjing
He, Chunqing
Peng, Xiangyang
Huang, Zhen
Fang, Pengfei
Powiązania:: https://bibliotekanauki.pl/articles/1033239.pdf
Data publikacji:: 2017-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: epoxy coating
photo-degradation
ultraviolet absorber
slow positron beam
microstructure
Opis:: The photo-degradation progress of epoxy coating and the effect of ultraviolet absorber under UV-B irradiation have been investigated in slow positron beam and by the Fourier transform infrared spectrometer. After 120 h of irradiation, the value of S parameter in sample bulk is reduced while compared with the virgin sample. The result is mostly due to post-cure process happening in this initial irradiation stage. As the irradiation time increases to 360 h, the S parameter decreases sharply. This is due to the growth of carbonyl group and the generation of free radical. After 528 h or longer time of irradiation, a very low S value was obtained near sample surface, indicating the formation of a dead surface layer. Positron results also reveal that the addition of ultraviolet absorber suppresses the development of the dead layer after long-term UV-B irradiation. Ultraviolet absorber has a suppressing effect on generation of polar groups towards sample bulk. The addition of ultraviolet absorber is a key factor that affects the photo-degradation of epoxy coating.
Źródło:: Acta Physica Polonica A; 2017, 132, 5; 1523-1526
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Photo-oxidative Aging Behaviors of Acrylic Coatings during UV Irradiation Investigated by Positron Annihilation Spectroscopy
Autorzy:: Zhao, Xipo
Cai, Xiaolin
Liu, Chang
Chen, Ting
He, Chunqing
Fang, Pengfei
Peng, Shaoxian
Powiązania:: https://bibliotekanauki.pl/articles/1033253.pdf
Data publikacji:: 2017-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: Acrylic coating
UV irradiation
positron annihilation spectroscopy
Opis:: Slow positron annihilation spectroscopy, contact angle and scanning electron microscope (SEM) were employed to investigate the surface polarity and morphologies as functions of aging time in acrylic coatings during UV-a irradiation. The S parameter plots of each exposed sample are lower than that of the virgin sample in the whole range of E. The S parameter plots become lower as the exposing longer time, indicated that the irradiation generated more polar groups and increased the oxidation layer depth. Combined with surface morphology and the surface energy of acrylic coating, the variation of contact angle, and surface energy, polar component and dispersive component is related with surface polarity and morphologies.
Źródło:: Acta Physica Polonica A; 2017, 132, 5; 1527-1530
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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