Positron Spectroscopy of Free Volume in Poly(vinylidene fluoride) after Helium Ions Irradiation

Jin Zhe Lyu, Roman Laptev, Natalya Dubrova

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Free volume is an extremely important intrinsic defect in polymers. Structurally, free volume is the randomly distributed holes in the polymer molecular chain segments. In proton exchange membrane fuel cells, free volume is also the space needed for the directional conduction of protons. Irradiation by α particles to grafting sulfonated poly(vinylidene fluoride) (PVDF) is one of the methods to produce proton exchange membrane with good proton channel rate. Positron annihilation lifetime spectroscopy was used to study the free volume size at different absorbed dose levels from 0.13 MGy to 0.65 MGy. Measurement method of positron annihilation lifetime spectroscopy for PVDF based on 44 Ti positron source was developed. For low dose irradiation at 0.26 MGy, a decrease in free volume and practically unchanged crystallinity were observed. Further increase of absorbed dose range from 0.26 MGy to 0.39 MGy led to an increasing crystallinity with the same free volume level. For the absorbed dose from 0.39 MGy to 0.65 MGy, crystallinity was decreased but free volume remained almost constant.

Original languageEnglish
Pages (from-to)527-534
Number of pages8
JournalChinese Journal of Polymer Science (English Edition)
Issue number5
Publication statusPublished - 1 May 2019


  • Connection
  • Degradation
  • Free volume
  • Helium ions
  • Poly(vinylidene fluoride)
  • Positron annihilation
  • XRD

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Organic Chemistry
  • Polymers and Plastics

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