Molecular rearrangements in ultra high molecular weight polyethylene after irradiation and long-term storage in air
| Autor: | Murali Jasty, V. Premnath, Anuj Bellare, Edward W. Merrill, William H. Harris |
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| Rok vydání: | 1999 |
| Předmět: |
Ultra-high-molecular-weight polyethylene
Polymers and Plastics Chemistry Small-angle X-ray scattering Organic Chemistry Polyethylene Photochemistry Crystallinity chemistry.chemical_compound Differential scanning calorimetry Nuclear magnetic resonance Decalin Materials Chemistry Irradiation Fourier transform infrared spectroscopy |
| Zdroj: | Polymer. 40:2215-2229 |
| ISSN: | 0032-3861 |
| Popis: | Molecular rearrangements and alterations in supermolecular structure of ultra high molecular weight polyethylene (UHMWPE) due to cross-linking and oxidation-induced chain scission following irradiation and subsequent storage in air at room temperature have been studied over a period of 29 months. The techniques that were used are: equilibrium swelling in decalin, differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR) and electron spin resonance (ESR). The experimental results indicate that immediately after irradiation, cross-linking and an increase in crystallinity are the important processes. With time, chain scission induced by oxidation takes place resulting in a new phase of thinner crystallites in the amorphous region. In the absence of oxygen diffusion limitations, the free radicals survive for 30 months in the form of peroxides. The effect produced by higher doses and shorter aging times correspond to those produced by lower doses and longer aging times, thus, suggesting a superposition law between dose and aging time. |
| Databáze: | OpenAIRE |
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