Reactive extrusion, a way to solvent free processing and new materials

Extruders are traditionally used in industry to melt, mix and shape polymeric materials. Due to their ability to process high viscous materials they can be used as a novel type of reactor. It is possible to use extruders as solvent free polymerisation or modification reactors. In situ compatibilisation during mixing of incompatible polymers is another interesting application of these machines. A third area, where extruders can be used as reactors is in the gelatinisation and modification of starches to use them as a base chemical from renewable resources. In this way it is also possible to produce copolymers between starches and synthetic polymers that can be used for packaging, disposables and controlled release

Metal-ceramic interfaces studied with high-resolution transmission microscopy

This paper reports on investigations of Ag-ZnO and Cu-ZnO interfaces, produced by internal oxidation. ZnO precipitates with the wurtzite structure were found showing mainly one orientation relationship( OR) with the matrix. However, closely related ORs were found, rotated by small angles from that orientation relation. The atomic structure of several interfaces surrounding these precipitates was studied and compared using high resolution transmission electron microscopy. This paper focuses on interfaces between low index facets of ZnO and vicinal planes of Ag. These interfaces clearly show relaxations. An interpretation of these relaxations in terms of dissociation of partial dislocations at the interface is put forward

Core-shell latices based on conductive polymers

A poly(butyl methacrylate) (PBMA) latex was coated with a thin polypyrrole (PPy) layer in a chemical in situ polymerization. Ammonium persulfate and Fenton's reagent were used as the oxidants. The influence of reaction time on the conversion of pyrrole and on the conductivity of the resulting coated latices was investigated. Furthermore, the influence of the reaction atmosphere was investigated. It was found that the ammonium persulfate-oxidized reaction was quite insensitive towards the reaction atmosphere, whereas the Fenton's reagent oxidized system was very sensitive. In the latter system, when kept in air the conductivity reached a maximum after 30 minutes. In a nitrogen reaction atmosphere the conductivity gradually increased. The maximum conductivity, which was about 20 times as high as in air, was reached after 90 minutes and remained stable