| Autor: |
Cifraničová, Katarína, Královič, Dávid P., Šauša, Ondrej, Švajdlenková, Helena |
| Zdroj: |
Chemical Papers; Dec2023, Vol. 77 Issue 12, p7277-7282, 6p |
| Abstrakt: |
The photopolymerization process of a liquid mixture of monomers (2 M) and photoinitiator (PI) takes place under specific and controllable conditions. UV light-induced photopolymerization of mixture leads to the reactions of a photoinitiator with a monomer to produce a polymer. The microstructural properties of the materials were measured by positron annihilation spectroscopy. The lifetime of orthopositronium (o-Ps) (τo–Ps) obtained from the complex annihilation time spectrum monitors the influence of various chemical and physical parameters on the change of local free volume. The structural changes of the mixture of two dimethacrylates (2 M) with a small amount of photoinitiator (PI) were investigated during periodically illumination of two differently thick samples by positron annihilation lifetime spectroscopy (PALS). Samples were cured for a specific time, when a constant lifetime of o-Ps reflecting free volume was reached. It was found that the 2 mm sample (2 M-2 mm) cross-links faster and reaches a more reduced local free volume in the structure compared to the 5 mm sample (2 M-5 mm). Moreover, the near-infrared (NIR) spectra and bulk density of both cured samples revealed the molecular and micro-structural relations for two different thick samples. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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