Filtern
Dokumenttyp
- Zeitschriftenartikel (3) (entfernen)
Sprache
- Englisch (3)
Referierte Publikation
- ja (3)
Schlagworte
- Poly(methyl methacrylate) (3) (entfernen)
Polylactide (PLA) and poly(methyl methacrylate) (PMMA) constitute, already for several decades, the gold standards for various biomedical applications due to their biocompatibility/inertness. Moreover, they have an additional property: they can form stereocomplexes (SCs) that have a more compact crystalline structure than the individual components. As a result, polymer SCs display improved thermal and mechanical properties, as well as delayed drug release and biodegradation rate in the case of drug delivery systems and biomaterials based on PLA, which is of prime importance in the biomedical field. In this article, the potential of SCs for biomedical applications in the areas of drug delivery, tissue engineering, and nanostructured surfaces is highlighted.
On the basis of two examples, temperature measurements are proposed within burning polymer specimen during the cone calorimeter test; especially to gain deeper insight into the actual pyrolysis conditions and flame retardancy mechanism. The heating and pyrolysis within a poly(methyl methacrylate) specimen were characterized, discussing the characteristic maximum heating rates (165-90°Cmin-1 decreasing with depth within the specimen and >275°Cmin-1 at the initial surface), pyrolysis temperature (454-432°C decreasing in accordance with decreasing heating rates), thickness of the pyrolysis zone (0.5-1.3 mm) and its velocity (1.2-2.1 mm min-1) as a function of sample depth and burning time. Thermally thick behaviour corresponds to a pyrolysis zone thickness of 0.74 mm and a velocity of 1.51 mm min-1 and occurs until the remaining specimen thickness is less than 8 mm. The shielding effect against radiation occurring in a layered silicate epoxy resin nanocomposite was investigated. It is the main flame retardancy effect of the silicate-carbon surface layer formed under fire. The reradiation from the hot surface is increased by a factor of around 4-5 when an irradiance of 70kWm-2 is applied. The energy impact into the pyrolysis zone is crucially reduced, resulting in a reduction of fuel production and thus heat release rate.