## Abstract The non‐parallel chain structure determined for γ‐phase isotactic polypropylene (γ‐iPP) is confirmed by Rietveld analysis for highly isotactic high molecular mass iPP crystallized at 200 MPa. The new refinement shows that: (i) stereoregularity or crystallization pressure do not signific
Study of the effect of γ-dose rate on the oxidation of polypropylene
✍ Scribed by Adams Tidjani; Yasushi Watanabe
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 560 KB
- Volume
- 60
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Polypropylene PP (high and low crystallinity) was y-oxidized, in the presence of air, using different dose rates (from 2 to 100 rad/s). Oxidation outcomes were identified and quantified by FTIR spectroscopy coupled with derivatization reactions (NO and SF,). The difficulty to separate secondary and tertiary hydroperoxides from FTIR measurements after NO treatment was addressed. Polymer physical degradation was also monitored during the y-irradiation process. GPC was used to follow molecular weight changes and tensile tests for elongation at break modifications. Comparison of the extent of oxidation product formation over y-irradiation allowed us to investigate the importance of y-dose rate on chemical and physical changes of PP. From this, different mechanisms of ketone and ester formation were examined relationship between the molecular weight changes and the elongation at break modifications was also investigated.
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