Polylactide compositions. II. Correlation between morphology and main properties of PLA/calcium sulfate composites

Starting from calcium sulfate (gypsum) as fermentation by‐product of lactic acid production process, high performance composites have been produced by melt‐blending polylactide (PLA, L/D isomer ratio of 96:4) and β‐anhydrite II (AII) filler, that is, calcium sulfate hemihydrate previously dehydrated at 500 °C. Characterized by attractive mechanical and thermal properties due to good filler dispersion throughout the polyester matrix, these composites are interesting for potential use as biodegradable rigid packaging. Physical characterization of selected composites filled with 20 and 40 wt % AII has been performed and compared to processed unfilled PLA with similar amorphous structure. State of dispersion of the filler particles and interphase characteristic features have been investigated using light microscopy (LM) and scanning electron microscopy (SEM). Addition of AII did not decrease PLA thermal stability as revealed by thermogravimetry analyses (TGA) and allowed reaching a slight increase of PLA crystallizability during melt crystallization and upon heating from the glassy, amorphous state (DSC). It was found by thermomechanical measurements (DMTA) that the AII filler increased pronouncedly storage modulus (E′) of the composites in comparison with PLA in a broad temperature range. The X‐ray investigations showed stable/unchanged crystallographic structure of AII during processing with molten PLA and in the composite system. The notable thermal and mechanical properties of PLA–AII composites are accounted for by the good filler dispersion throughout the polyester matrix confirmed by morphological studies, system stability, and favorable interactions between components. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2770–2780, 2007     

Über die Picardgruppen affinoider Algebren

Ohne Zusammenfassung     

A note on asymptotic homomorphisms

Using the notion of asymptotic homomorphism due to Connes and Higson we construct bivariant homology-cohomology theories for separableC*-algebras, which satisfy general excision axioms and are nonperiodic.     

Austauschreaktionen der Cellulose im wasserfremden Medium

Zusammenfassung Es wird das Verhalten der Kristallviolettbase in absol.-benzol. Lösung gegenüber benzolgequollener Cellulose mit neutralisierten (versalzten bzw. veresterten) COOH-Gruppen unter-sucht.Der Einfluß des Kations auf die Umsetzung wird einer ersten Prüfung unterzogen.Herrn Prof. Dr.A. Zinke zum 70. Geburtstag gewidmet.     

On the Best Constants in Some Non-Commutative Martingale Inequalities

The optimal orders are determined for the best constants inthe non-commutative Burkholder–Gundy, Doob and Stein inequalitiesobtained recently in non-commutative martingale theory. 2000Mathematics Subject Classification 46L53, 46L51.