Modifizierungen der Oberfläche von Polyethylen und Polypropylen

Niederenergetische Kunststoffe, wie die Polyolefine Polyethylen oder Polypropylen, sind nur schwer zu kleben oder zu bedrucken. Die Herausforderung kann gelöst werden mit einer Methode, die ursprünglich aus der Biochemie stammt und mit der sich die Oberflächen von solchen Kunststoffen chemisch verändern lassen. Am Beispiel von photoreaktivem Skiwachs, einer hydrophoben Modifikation von Polyethylen, wird das Verfahren veranschaulicht

Schepeneses mumifizierte Organe

Four mysterious packages were found on the abdomen and legs of the mummy of Schepenese when she was unwrapped in 1993. Here we show by chemical analysis that at least one of them contains human tissue, presumably the intestines, sodium chloride, bitumen ans sand. The composition of a sample is to 85% of organic origin (about 71% human tissue and 14% bitumen), about 9% is common salt and 6% is desert sand. It is concluded that Schepenese's viscera were preserved with common salt and bitumen. Trace analysis displays enhanced values of molybdenum. The occurrence of this metal is linked to bitumen used for mummification

A moisture-absorbing and abrasion resistant transparent coating on polystyrene

A common phenomenon concerning cold surfaces which are subjected to a warmer, more humid atmosphere is condensation in the form of water droplets (fogging) or even ice crystals (icing). Thus, a previously transparent object becomes opaque because light is scattered by the droplets or crystals. This may impair the usability of that object. We developed an anti-fogging/icing coating which overcomes the problem of fogging and icing by being able to absorb the condensing water and preventing it from crystallizing. The coating consists of poly(1-vinyl-2-pyrrolidone) (PVP) crosslinked by UV light using hydrogen peroxide (H2O2). Benzophenone (BP) is used to attach PVP to the surface of the polystyrene (PS) substrate. At temperatures as low as -60°C, the PVP coating can absorb up to 70 wt% of water and still inhibit its crystallization. However, at surface temperatures of around -18°C, opacity is only observable at 150 wt% of absorbed water and higher. An increasing coating thickness as well as a decreasing crosslink density improves the anti-fogging/icing effect because the coating can absorb more water. The abrasion resistance of the coating is impaired by a decreasing crosslink density

EU-konform und dennoch verschweissbar

Die Recycelvorschriften der EU verlangen nach immer sortenreinerem Papierabfall. Papier wird in Lebensmittelverpackungen verwendet, wo es verschweisst werden muss. Um zwei Papierstreifen miteinander verschweissen zu können, müssen diese mit einem Fremdmaterial beschichtet sein. Das IMPE entwickelte zusammen mit der Firma Tanner & Co. AG eine neuartige Dispersionsbeschichtung für Papier, welche den Vorschriften der EU entspricht und dennoch verschweissbar ist

Sol-gel coatings with lime repellent properties

Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Calcification of surfaces by hard water represents a major issue for sanitary installations. Calcium carbonate precipitates forming crusts of lime that are difficult to remove. Much effort has been undertaken to avoid scaling, most methods require chemicals or create waste. We constructed a test rig which allows for the controlled calcification of various substrates. It is found that all solid surfaces investigated calcify more or less evenly. On the other hand, surface bound poly(ethylene glycol), PEG, is known to prevent the non-specific adsorption of biomolecules. PEG coated surfaces find their use in a variety of applications. Here we show that glass and plastics, such as polyethylene, polypropylene and acrylonitrile-butadiene-styrene, can be efficiently made lime repellent by the use of sol-gel coatings containing a PEG bearing silane. It is shown that the amount of scaling is drastically reduced. Prior to coating, plastics have to be pretreated by oxygen plasma and an adhesion promoter has to be employed

Sol-gel coatings with lime repellent properties

Calcification of surfaces by hard water represents a major issue for sanitary installations. Calcium carbonate precipitates forming crusts of lime that are difficult to remove. Much effort has been undertaken to avoid scaling, most methods require chemicals or create waste. We constructed a test rig which allows for the controlled calcification of various substrates. It is found that all solid surfaces investigated calcify more or less evenly. On the other hand, surface bound poly(ethylene glycol), PEG, is known to prevent the non-specific adsorption of biomolecules. PEG coated surfaces find their use in a variety of applications. Here we show that glass and plastics, such as polyethylene, polypropylene and acrylonitrile-butadiene-styrene, can be efficiently made lime repellent by the use of sol-gel coatings containing a PEG bearing silane. It is shown that the amount of scaling is drastically reduced. Prior to coating, plastics have to be pretreated by oxygen plasma and an adhesion promoter has to be employe