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Wyświetlanie 1-3 z 3
Tytuł:
Structural Changes in Surface-Modified Polymers for Medical Applications
Autorzy:
Pamula, E.
Dryzek, E.
Powiązania:
https://bibliotekanauki.pl/articles/1812545.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.35.-x
82.35.Lr
78.70.Bj
83.85.Jn
68.37.Ps
Opis:
Biological properties of synthetic polymers can be improved by surface modification with the use of liquid oxidizers. A resorbable biomedical polymer - poly(glycolide-co-ε-caprolactone) (PGCL) was incubated in 0.1 M NaOH for 2, 6, 16, and 24 h, followed by excessive washing and drying in vacuum. Surface properties of the materials before and after modification were evaluated: wettability by contact angle measurements, topography by atomic force microscopy, and chemical functions by infrared spectroscopy. Applied modification improved wettability of PGCL due to creation of chemical oxygenated functionalities, and resulted in a slight alternation of the surface topography and roughness. In order to determine whether NaOH incubation caused structural changes in bulk of PGCL, positron annihilation lifetime spectroscopy, differential scanning calorimetry and viscosity measurements were performed. It was found that the ortho-positronium lifetime in PGCL declines as a function of modification time. It suggests that NaOH incubation causes structural changes in PGCL not only on the surface but also in bulk.
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1485-1493
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Local Rigidity as a Criterion of Gas Permeation of Polymer and Composition Materials; PAL and TSL Experiments
Autorzy:
Shantarovich, V.
Gustov, V.
Belousova, E.
Polyakova, A.
Bekeshev, V.
Kevdina, I.
Yampolskii, Yu.
Pastukhov, A.
Powiązania:
https://bibliotekanauki.pl/articles/1196455.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.41.+e
61.43.Fs
68.43.Vx
78.70.Bj
82.35.Lr
Opis:
Various commercial and industrial properties of polymeric materials can be developed by the way of purposeful synthesis. For example, there are polymeric materials of extremely developed intrinsic microporosity. In attempts to further develop membrane properties (permeability and selectivity), the researchers artificially increase the pore sizes by various external influences, such as plastification by saturation of polymers with gases, sometimes in supercritical state, filling of a polymer with some non-organic components (zeolites). Sometimes, porosity of the composition appears to become higher than that of the components. This porosity, in difference with intrinsic one, can be called externally affected. The reason of these phenomena is not always clear, and in order to get some ideas in this field we suggest an experimental study using a combination of the two genetically interconnected (by spur processes) methods: positron annihilation lifetime spectroscopy and thermostimulated luminescence. This paper summarizes recently published and completely new results of the authors in order to illustrate the benefits of this experimental approach.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 806-811
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydrolytic Degradation of Poly(L-Lactide-co-Glycolide) Studied by Positron Annihilation Lifetime Spectroscopy and Other Techniques
Autorzy:
Pamuła, E.
Dryzek, E.
Dobrzyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/2047148.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.35.-x
82.35.Lr
78.70.Bj
61.18.Fs
82.56.Ub
83.85.Jn
68.37.Ps
Opis:
Changes of the poly(L-lactide-co-glycolide) structure as a function of degradation time in phosphate-buffered saline for 7 weeks were investigated by gel permeation chromatography, differential scanning calorimetry, nuclear magnetic resonance ($\text{}^{1}$H NMR), and positron annihilation lifetime spectroscopy. Surface properties as wettability by sessile drop and topography by atomic force microscopy were also characterized. Chain-scission of polyester bonds in hydrolysis reaction causes a quite uniform decrease in molecular weight, and finally results in an increase in semicrystallinity. Molecular composition of the copolymer and water contact angle do not change considerably during degradation time. Atomic force microscopy studies suggest that the copolymer degrades by "in bulk" mechanism. The average size of the molecular-level free volume holes declines considerably after one week of degradation and remains constant till the sixth week of degradation. The free volume fraction decreases as a function of degradation time.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 631-640
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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