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Analysis Of Positron Lifetime Spectra In Polymers
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722234904 Total Pages :64 pages Book Rating :4.2/5 (349 download)
Book Synopsis Analysis of Positron Lifetime Spectra in Polymers by : National Aeronautics and Space Administration (NASA)
Download or read book Analysis of Positron Lifetime Spectra in Polymers written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new procedure for analyzing multicomponent positron lifetime spectra in polymers was developed. It requires initial estimates of the lifetimes and the intensities of various components, which are readily obtainable by a standard spectrum stripping process. These initial estimates, after convolution with the timing system resolution function, are then used as the inputs for a nonlinear least squares analysis to compute the estimates that conform to a global error minimization criterion. The convolution integral uses the full experimental resolution function, in contrast to the previous studies where analytical approximations of it were utilized. These concepts were incorporated into a generalized Computer Program for Analyzing Positron Lifetime Spectra (PAPLS) in polymers. Its validity was tested using several artificially generated data sets. These data sets were also analyzed using the widely used POSITRONFIT program. In almost all cases, the PAPLS program gives closer fit to the input values. The new procedure was applied to the analysis of several lifetime spectra measured in metal ion containing Epon-828 samples. The results are described. Singh, Jag J. and Mall, Gerald H. and Sprinkle, Danny R. Goddard Space Flight Center; Langley Research Center...
Book Synopsis Analysis of Positron Lifetime Spectra in Polymers by : Jag J. Singh
Download or read book Analysis of Positron Lifetime Spectra in Polymers written by Jag J. Singh and published by . This book was released on 1988 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Positron Lifetime Spectra in Polymers by : Jag G. Singh
Download or read book Analysis of Positron Lifetime Spectra in Polymers written by Jag G. Singh and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Lifetime Spectroscopy for Investigation of Thin Polymer Coatings by : Jag J. Singh
Download or read book Positron Lifetime Spectroscopy for Investigation of Thin Polymer Coatings written by Jag J. Singh and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of Positron Lifetime Spectra in Polymers by : Jag G. Singh
Download or read book Analysis of Positron Lifetime Spectra in Polymers written by Jag G. Singh and published by . This book was released on 1988 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Free-volume Properties in Polymers by Positron Annihilation Spectroscopy by : Qin Deng
Download or read book Characterization of Free-volume Properties in Polymers by Positron Annihilation Spectroscopy written by Qin Deng and published by . This book was released on 1993 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Measurements of Microscopic Voids in Polymers Using Positron Annihilation Lifetime Spectroscopy by : Li Xie
Download or read book Measurements of Microscopic Voids in Polymers Using Positron Annihilation Lifetime Spectroscopy written by Li Xie and published by . This book was released on 1995 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Lifetime Spectroscopy on Selected Polymers by : Ronghai Wang
Download or read book Positron Lifetime Spectroscopy on Selected Polymers written by Ronghai Wang and published by . This book was released on 1992 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Annihilation Spectroscopy of High Performance Polymer Films Under CO2 Pressure by :
Download or read book Positron Annihilation Spectroscopy of High Performance Polymer Films Under CO2 Pressure written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron annihilation Lifetime and Doppler broadening measurements are reported for six polymer films as a function of carbon dioxide absolute pressure ranging from 0 to 45 psi. Since the polymer films were thin and did not absorb all positrons, corrections were made in the lifetime analysis for the absorption of positrons in the positron source and sample holder using the Monte Carlo transport code MCNP. Different polymers are found to behave differently. Some polymers studied form positronium and some, such as the polyimide structures, do not. For those samples that form positronium an interpretation in terms of free volume is possible; for those that don't form positronium, further work is needed to determine how best to describe the behavior in terms of the bulk positron annihilation parameters. Some polymers exhibit changes in positron lifetime and intensity under CO2 pressure which may be described by the Henry or Langmuir sorption models, while the positron response of other polymers is rather insensitive to the CO2 pressure. The results demonstrate the usefulness of positron annihilation spectroscopy in investigating the sorption of CO2 into various polymers at pressures up to about 3 atm.
Book Synopsis Positron Lifetime Studies of Polyaniline Conducting Polymers by : Chia-Ming Huang
Download or read book Positron Lifetime Studies of Polyaniline Conducting Polymers written by Chia-Ming Huang and published by . This book was released on 1995 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Annihilation Spectroscopy: A Nondestructive, Submicroscopic Characterization Technique for Structural Polymers by :
Download or read book Positron Annihilation Spectroscopy: A Nondestructive, Submicroscopic Characterization Technique for Structural Polymers written by and published by . This book was released on 1989 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron annihilation lifetime spectroscopy (PALS) has been used to characterize as extruded and aged LEXAN polycarbonate. The long-lived component of the PALS analysis is attributed to orthoPositronium (oPs) pick off annihilations. The oPs pickoff component lifetime and intensity decrease as the result of the aging heat treatment, and this decrease is associated with a decrease in the free volume site size and concentration in glassy polycarbonate due to aging. Isothermal relaxation experiments performed over the range 12 C to 30 C performed on as-extruded and aged polycarbonate indicate that the relaxation kinetics are significantly different, and are consistent with a decrease in molecular mobility as the result of aging. An activation energy for structural relaxation of 8.2 kcal/mole for aged polycarbonate versus 3.0 kcal/ mole for unaged polycarbonate was determined. The relaxation kinetics observed using PALS is related to the structural state and molecular mobility of the polymer.
Book Synopsis Microstructural Characterization of Polymers by Positron Lifetime Spectroscopy by : Jag J. Singh
Download or read book Microstructural Characterization of Polymers by Positron Lifetime Spectroscopy written by Jag J. Singh and published by . This book was released on 1996 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Free-volume Hole Properties of Gas-exposed Polymers Studied by Positron Annihilation Spectroscopy by : Xiaoyong Hong
Download or read book Free-volume Hole Properties of Gas-exposed Polymers Studied by Positron Annihilation Spectroscopy written by Xiaoyong Hong and published by . This book was released on 1996 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Positron Lifetime Changes in Gamma- And Beta-Irradiated Polymers by : Ahmed A. Selman
Download or read book Positron Lifetime Changes in Gamma- And Beta-Irradiated Polymers written by Ahmed A. Selman and published by LAP Lambert Academic Publishing. This book was released on 2012-05 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Positron is the simplest antimatter particle, and it is the electron's unsociable twin, they have identical characters with opposite electric charges. Thus, when they meet spatially they annihilate each other. This particle has drawn attention since the early days of nuclear era, since it proved vital theories such as Einstein's mass-energy equivalence law. The existence of such natural entities is, however, ruled by many physical laws similar to those of the (negative) electron. This book discusses the physical nature of positrons in a straightforward yet explicable way and reviews the wide scientific applications, specially experimental ones, by means of the nondestructive Positron Annihilation Lifetime Spectroscopy (PALS). The applications are focused on solid organic polymer samples, vis., LDPE, HDPE and PMMA, subjected to gamma and beta low dose nuclear radiations. PALS spectra are collected in the laboratory and used to calculate the free volume (Vh), a micro-physical quantity aimed to explore the molecular structure of industrial substances. The correlation between radiation damages and Vh is thoroughly discussed and compared for both types of radiations.
Book Synopsis Positrons in Solids by : P. Hautojärvi
Download or read book Positrons in Solids written by P. Hautojärvi and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: In condensed matter initially fast positrons annihilate after having reached equi librium with the surroundings. The interaction of positrons with matter is governed by the laws of ordinary quantum mechanics. Field theory and antiparticle properties enter only in the annihilation process leading to the emergence of energetic photons. The monitoring of annihilation radiation by nuclear spectroscopic methods provides valuable information on the electron-positron system which can directly be related to the electronic structure of the medium. Since the positron is a positive electron its behavior in matter is especially interesting to solid-state and atomic physi cists. The small mass quarantees that the positron is really a quantum mechanical particle and completely different from any other particles and atoms. Positron physics started about 25 years ago but discoveries of new features in its interac tion with matter have maintained continuous interest and increasing activity in the field. Nowadays it is becoming part of the "stock-in-trade" of experimental physics.
Book Synopsis Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy by : Jag J. Singh
Download or read book Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy written by Jag J. Singh and published by . This book was released on 1996 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Principles and Applications of Positron & Positronium Chemistry by : Y. C. Jean
Download or read book Principles and Applications of Positron & Positronium Chemistry written by Y. C. Jean and published by World Scientific. This book was released on 2003 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive description of the principles and applications of positron and positronium chemistry. Pedagogical and tutorial in nature, it will be ideal for graduate students and researchers in the area of positron annihilation spectroscopy. The contributing authors are authoritative scientists prominent in the frontiers of research, actively pursuing positron annihilation research on chemical and applied systems. Contents: Introduction to Positron and Positronium Chemistry (Y C Jean et al.); Compounds of Positrons and Positronium (D M Schrader); Experimental Techniques in Positron Spectroscopy (P G Coleman); Organic and Inorganic Chemistry of the Positron and Positronium (G Duplotre & I Billard); Physical and Radiation Chemistry of the Positron and Positronium (S V Stepanov & V M Byakov); Positrons and Positronium in the Gas Phase (D M Schrader); Positron Porosimetry (M H Weber & K G Lynn); Positron Annihilation Studies on Superconducting Materials (C S Sundar); Positronium in Si and SiO 2 Thin Films (R Suzuki); Applications to Polymers (P E Mallon); Applications of Slow Positrons to Polymeric Surfaces and Coatings (Y C Jean et al.); Positron Annihilation Induced Auger Spectroscopy (S Amdani et al.); Characterization of Nanoparticle and Nanopore Materials (J Xu); AMOC in Positron and Positronium Chemistry (H Stoll et al.). Readership: Materials science researchers; physical chemists; polymer scientists and engineers; chemical and mechanical engineers; solid state physicists; graduate students in chemistry, physics, engineering and polymer science; coating industry researchers."
