scholarly journals Low Molecular Weight ‘Liquid’ Polymer Extended Compounds Impact on Free Volume and Crosslink Density studied by Positron Lifetime Spectroscopy and Stress-Strain Analysis according to Mooney-Rivlin

2021 ◽  
pp. 107239
Author(s):  
M. Gruendken ◽  
D. Koda ◽  
J. Dryzek ◽  
A. Blume
Keyword(s):  
Molecular Weight ◽  
Free Volume ◽  
Crosslink Density ◽  
Positron Lifetime ◽  
Strain Analysis ◽  
Low Molecular Weight ◽  
Stress Strain ◽  
Liquid Polymer ◽  
Positron Lifetime Spectroscopy

Molecular Packing of Carbohydrate Oligomer Encapsulants - A Free Volume Perspective

2012 ◽  
Vol 733 ◽  
pp. 96-99 ◽  
Author(s):  
Mina Roussenova ◽  
Sam Townrow ◽  
Mathieu Murith ◽  
Job Ubbink ◽  
M. Ashraf Alam
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
Free Volume ◽  
Glassy State ◽  
Low Molecular Weight ◽  
Hole Size ◽  
Positron Annihilation Lifetime ◽  
Food Industries ◽  
Molecular Organisation ◽  
Complex Manner

Positron annihilation lifetime spectroscopy (PALS) is used in conjunction with dilatometry to analyse the effects of water and low molecular weight diluents (maltose and glycerol) on the molecular organisation and density of carbohydrate oligomers commonly used in the pharmaceutical and food industries for the formulation of encapsulation matrices. In the glassy state, both maltose and glycerol act as packing enhancers, causing a non-linear decrease in the average molecular hole size of the carbohydrate matrices. Water exists in a highly non-ideal state in these systems and it alters the molecular organisation of the matrices in a complex manner, whereby it can act either as an anti-plasticiser or a plasticiser, depending on the level of hydration.

Temperature and time dependence of free volume in bisphenol A polycarbonate studied by positron lifetime spectroscopy

1992 ◽  
Vol 25 (19) ◽  
pp. 5089-5093 ◽  
Author(s):  
J. E. Kluin ◽  
Z. Yu ◽  
S. Vleeshouwers ◽  
J. D. McGervey ◽  
A. M. Jamieson ◽  
...  
Keyword(s):  
Bisphenol A ◽  
Time Dependence ◽  
Free Volume ◽  
Positron Lifetime ◽  
Bisphenol A Polycarbonate ◽  
Positron Lifetime Spectroscopy

Effect of Water on the Size Distribution of Free-Volume Holes in Nafion Membrane

2012 ◽  
Vol 733 ◽  
pp. 49-52 ◽  
Author(s):  
Jakub Čížek ◽  
Zuzana Barnovská ◽  
Michal Šourek ◽  
Ivan Procházka
Keyword(s):  
Size Distribution ◽  
Free Volume ◽  
Water Uptake ◽  
Positron Lifetime ◽  
Ionic Clusters ◽  
Mean Size ◽  
Positron Lifetime Spectroscopy ◽  
The Mean ◽  
Kinetics Of

Positron lifetime spectroscopy was employed for investigation of the size distribution of free volume holes in Nafion N-1110 membrane. Size distribution of free volume holes was determined in the as-received and dried membrane and in the membrane immersed in water at various temperatures. It was found that absorbed water causes reduction of the mean size of free volume holes and increase of their dispersion and concentration. This indicates that free volumes are split by swollen ionic clusters absorbing water. The kinetics of water uptake and the amount of absorbed solvent was determined by in-situ measurement of the weight increase.

scholarly journals Free-Volume Studies in Polycaprolactone/Poly(propylene oxide) Urethane/Urea Membranes by Positron Lifetime Spectroscopy

2008 ◽  
Vol 113 (5) ◽  
pp. 1359-1364 ◽  
Author(s):  
M.F. Ferreira Marques ◽  
P.M. Gordo ◽  
A.P. de Lima ◽  
D.P. Queiroz ◽  
M. Norberta de Pinho ◽  
...  
Keyword(s):  
Free Volume ◽  
Propylene Oxide ◽  
Positron Lifetime ◽  
Positron Lifetime Spectroscopy ◽  
Poly Propylene

scholarly journals Temperature dependence of free volume distributions in polymers studied by positron lifetime spectroscopy

1993 ◽  
Vol 03 (C4) ◽  
pp. 265-270 ◽  
Author(s):  
J. KRIŠTIAK ◽  
K. KRIŠTIAKOVÁ ◽  
O. ŠAUŠA ◽  
P. BANDŽUCH ◽  
J. BARTOŠ
Keyword(s):  
Temperature Dependence ◽  
Free Volume ◽  
Positron Lifetime ◽  
Positron Lifetime Spectroscopy

Free-volume and crystallinity in low molecular weight poly(ethylene oxide)

2007 ◽  
Vol 45 (17) ◽  
pp. 2400-2409 ◽  
Author(s):  
José C. Machado ◽  
Glaura G. Silva ◽  
Fernando C. de Oliveira ◽  
Rodrigo L. Lavall ◽  
Jacques Rieumont ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ethylene Oxide ◽  
Free Volume ◽  
Low Molecular Weight ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Positron Lifetime Studies of Irradiated Ultra-High Molecular Weight Polyethylene and Composites Made of Martian Regolith

2014 ◽  
Vol 783-786 ◽  
pp. 1585-1590 ◽  
Author(s):  
Naidu V. Seetala ◽  
Naeem Tull-Walker ◽  
Abhijit Baburaj ◽  
Jian Ren Zhou ◽  
Richard Wilkins ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Positron Annihilation ◽  
High Molecular Weight ◽  
Free Volume ◽  
Irradiation Dose ◽  
Positron Lifetime ◽  
Positron Source ◽  
Vacancy Defects ◽  
Martian Regolith ◽  
Ultra High Molecular Weight

Positron Annihilation Lifetime Spectroscopy (PALS) is used to study the nanoporosity and fractional free volume in Ultra High Molecular Weight Polyethylene (UHMWPE) and composites with the addition of Martian Regolith (UHMWPE-MR) as-made and irradiated with56Fe heavy ions at an energy of 600 MeV/u to three different doses (10, 32, 64 Gy). The positron lifetime spectra were obtained using22Na positron source and the spectra were analyzed to two lifetime components using POSFIT program. First short lifetime component around 0.28 ns is related to positron annihilation in material including vacancy defects and the second long lived component around 1.7 ns is due to Positronium formation in free volume pores. UHMWPE-MR composites were shown to be less porous with much lower nanopores concentration compared to the UHMWPE polymer. The average size of the nanopores is around 0.5 nm (obtained from a simple model). Larger variations in positron lifetime parameters are observed with increasing irradiation dose for UHMWPE polymer compared to UHMWPE+MR composites. The 3-point bend test results also showed larger variations with increasing irradiation dose for the UHMWPE polymer. The variations in PALS parameters may indicate an increasing competition between two processes at higher irradiation doses: 1) vacancy defects aggregation and 2) escape of vacancy defects as the local temperature increases at higher doses resulting in increased vacancy defects mobility. Present results clearly indicate a qualitative inverse relationship between nanoscale porosity measured by positron life time and mechanical properties of UHMWPE and its composite with MR.

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