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Published on: October 3, 2025
Influence of polar groups in binary polymer blends on positronium formation
P Ramya1, P Guagliardo, T Pasang
1Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore-570006, India.
Summary
Unconjugated oxygen in polymer blends can inhibit positronium formation, similar to chlorine. This study found that the polar acetate group in EVA significantly reduced positronium, even with PVC present.
Area of Science:
- Materials Science
- Polymer Chemistry
- Radiochemistry
Background:
- Positronium (Ps) formation is sensitive to the electronic environment within materials.
- Polymer blends offer tunable properties, but the influence of specific polar groups on Ps inhibition requires further study.
Purpose of the Study:
- To investigate the role of unconjugated oxygen in polar groups on positronium formation inhibition in polymer blends.
- To compare the positronium inhibiting effects of different polar groups within polymer matrices.
Main Methods:
- Coincidence Doppler broadening and positron lifetime spectroscopy were employed.
- Analysis of polymer blend samples: PVC-EVA and PVC-SAN.
Main Results:
- The polar acetate group in EVA demonstrated significant positronium inhibition, causing approximately 28% reduction.
- Unconjugated oxygen in EVA contributed to positron annihilation, evidenced by momentum distribution curves.
- PVC-SAN blends showed no similar inhibition effect, attributed to the weakly polar acrylonitrile group.
Conclusions:
- Chlorine in PVC is a primary inhibitor of positronium formation via a (Cl(-)-e(+)) bound state.
- Unconjugated oxygen in EVA's polar groups also inhibits positronium formation, playing a significant but lesser role compared to chlorine.
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