Polypropylene Films Studied with Variable Positron Beams

• Authors: M. Dębowska , P. Coleman , D. Gidley
• Languages of publication: EN

Abstracts

EN

Doppler broadening and positron lifetime spectra have been measured for polypropylene films of constant thickness (≈ 50 μm) and different morphology that crystallized from melt at temperature 0, 100, and 120°C. The S -parameter vs. energy curves do not change in a systematic way with crystallinity of samples. It is supposed that decrease in the fractional free volume for samples of greater crystallinity is not seen in S-values because of their increase resulting from annihilation in defects present both in the crystalline regions and on the lamellae surfaces. Intensities of the components in the positron lifetime spectra: I_{2} (τ_{2}=1.3 ns) and I_{3} (τ_{3}≈ 2.3÷2.8 ns) show changes with crystallinity of samples. The evident trend is observed for the longer-lived τ_{3}-component intensity to decrease with crystallinity while the reverse is true for the shorter, fixed τ_{2}-component. The decrease in the intensity of the longer-lived component can result from reduction of the fractional free volume.

Keywords

EN

36.10.Dr; 61.41.+e; 71.60.+z; 78.70.Bj

Discipline

• 78.70.Bj: Positron annihilation(for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
• 71.60.+z: Positron states(for positron annihilation, see 78.70.Bj)
• 61.41.+e: Polymers, elastomers, and plastics(see also 81.05.Lg in materials science; for rheology of polymers, see section 83; for polymer reactions and polymerization, see 82.35.-x in physical chemistry and chemical physics)
• 36.10.Dr: Positronium(see also 82.30.Gg Positronium chemistry)

• Journal: Acta Physica Polonica A
• Year: 1999
• Volume: 95
• Issue: 4
• Pages: 496-504

Dates

published

1999-04

Contributors

author

M. Dębowska

• Institute of Experimental Physics, University of Wrocław, Pl. Maksa Borna 9, 50-204 Wrocław, Poland

author

P. Coleman

• School of Physics, University of East Anglia, Norwich NR4 7TJ, United Kingdom

author

D. Gidley

• Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA

Identifiers

DOI

10.12693/APhysPolA.95.496