FREE VOLUME RELATED STRUCTURAL CHANGES IN THE EPOXY POLYMER TGDDM

1994 ◽  
Vol 08 (13) ◽  
pp. 1699-1711 ◽  
Author(s):  
V. RAVINDRACHARY ◽  
R. RAMANI ◽  
C. RANGANATHAIAH ◽  
S. GOPAL
Keyword(s):  
Free Volume ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Epoxy Polymer ◽  
Slow Increase ◽  
Treatment Variation ◽  
Kinetic Relations ◽  
Long Lifetime ◽  
Average Size ◽  
Free Volume Hole

Positron lifetime measurements have been carried out in an amine-cured epoxy polymer TGDDM/DDS/BFE as a function of annealing temperature. The measured spectra are best fitted to three component analysis. From the measured long lifetime component the average size of the free volume holes has been calculated following Nakanishi et al.’s treatment. Variation of lifetime parameters with temperature indicates the preferential trapping of positronium atoms in the regions of increased free volume hole sizes. On the other hand, positrons are being trapped at micro-voids in the ordered regions. The slow increase of free volume upto 170°C may be due to the thermal expansion and we measure 170° C as the Tg for this epoxy. Lifetime data are also used to calculate the trapping rates in the ordered and disordered regions of the epoxy based on Goldanskii’s kinetic relations.

Pressure dependence of free-volume hole properties in an epoxy polymer

1992 ◽  
Vol 96 (1) ◽  
pp. 492-495 ◽  
Author(s):  
Q. Deng ◽  
C. S. Sundar ◽  
Y. C. Jean
Keyword(s):  
Free Volume ◽  
Pressure Dependence ◽  
Epoxy Polymer ◽  
Free Volume Hole

Structural Changes of UHV Deposited Titanium Thin Films in Presence of Oxygen Flow and Temperature

2011 ◽  
Vol 110-116 ◽  
pp. 1094-1098
Author(s):  
Haleh Kangarlou ◽  
Mehdi Bahrami Gharahasanloo ◽  
Akbar Abdi Saray ◽  
Reza Mohammadi Gharabagh
Keyword(s):  
Room Temperature ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Annealing Process ◽  
Oxygen Flow ◽  
Glass Substrates ◽  
Annealing Temperatures ◽  
Titanium Thin Films ◽  
Deposition Angle ◽  
Ti Films

Ti films of same thickness, and near normal deposition angle, and same deposition rate were deposited on glass substrates, at room temperature, under UHV conditions. Different annealing temperatures as 393K, 493K and 593K with uniform 8 cm3/sec, oxygen flow, were used for producing titanium oxide layers. Their nanostructures were determined by AFM and XRD methods. Roughness of the films changed due to annealing process. The gettering property of Ti and annealing temperature can play an important role in the nanostructure of the films.

Positronium Lifetime in an Ellipsoidal Free-Volume Hole of Polymers

1994 ◽  
Vol 175-178 ◽  
pp. 691-694 ◽  
Author(s):  
Yan Ching Jean ◽  
Hong Shi ◽  
G.H. Dai ◽  
C.M. Huang ◽  
John Liu
Keyword(s):  
Free Volume ◽  
Positronium Lifetime ◽  
Free Volume Hole

Preliminary Positron Lifetime Results on Free Volumes in Cyclodextrins

2010 ◽  
Vol 666 ◽  
pp. 99-102 ◽  
Author(s):  
Maria Fatima Ferreira Marques ◽  
A.M.G. Moreira Da Silva ◽  
P.M. Gordo ◽  
Z. Kajcsos
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Source ◽  
Lifetime Component ◽  
Positron Annihilation Lifetime ◽  
Long Lifetime

Positron annihilation lifetime spectroscopy was used to study the free-volume parameters in various pure -, - and -cyclodextrins samples and, in the case of β-cyclodextrin, with inclusion of S-carvone and thymoquinone. The results clearly indicate the presence of long lifetime components related to Ps-formation. The data show that the addition of S-carvone to β-cyclodextrin results in a decrease of o-Ps lifetime that we ascribe to a reduction of free volume holes from 81.8 to 63.7 Å3. The long lifetime component disappears when thymoquinone is added to -cyclodextrin, indicating this substance acts as an o-Ps quencher. For all samples studied, a decrease in the long lifetime component values was observed with increasing source in situ time, a result that might be attributed to the irradiation of the sample by the 22Na positron source.

scholarly journals Bandgap Engineering of Bilayer Ge/CdS Thin Films via Interlayer Diffusion under Different Annealing Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Faheem Amin ◽  
Syedah Afsheen Zahra ◽  
Muhammad Sultan ◽  
Sajjad Hussain Mirza ◽  
Fahad Azad
Keyword(s):  
Thin Films ◽  
Glass Substrate ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Thermal Evaporation ◽  
Rutherford Backscattering ◽  
Bandgap Engineering ◽  
Thermal Evaporation Method ◽  
Annealing Temperatures ◽  
Cds Thin Films

Bilayer thin films of Ge/CdS have been deposited on a glass substrate through thermal evaporation method. The obtained Ge/CdS samples were annealed at temperatures up to 400°C to observe the resulting effect on the structural changes in the film. The bandgap of the annealed films was found to increase with increasing annealing temperature which can be attributed to the increased interlayer diffusion. The interlayer diffusion was found to take effect above a temperature of 300°C which was confirmed by the Rutherford backscattering technique. Complementary XPS was done to investigate the surface stoichiometry of the bilayers.

Sign in / Sign up

Export Citation Format

Share Document