In addition to acting as a service provider, we offer advice to our customers wishing to crosslink, modify or sterilize their products by having them treated in our systems.
A selection of the products which we treat with our electron-beam units:
- Cables and wires
- Plastic pipes
- Shrink-fit tubing Implants (e.g. joints with integrated synthetic sliding surfaces)
- Foam sheeting for automobile construction and other applications
- Plastic injection moulded components (housings, seals, gears)
- Electrical and electronic components
- Ultra high molecular weight polyethylene for implants
Our plants are designed for very specific product groups and thus have equipment that enables optimum handling. This ranges from special single part and box transport systems to winding systems for cables and pipes that can be used in a variety of ways.
Crosslinking · Electron beams
High energy electrons create free radicals which combine to create new bonds releasing Hydrogen
Crosslinking is a way of improving certain properties of plastics to enable them to be used to replace more expensive, usually harder to handle high-performance plastics. This is particularly effective as a way to increase dimensional stability under the influence of heat. The much-enhanced dimensional stability under thermal influences is not the only material improvement that arises as a result of crosslinking.
Crosslinked plastics not only more resistant to deformation at high temperatures, but are also:
- more resistant to chemicals
- more resistant to solvents (enhanced resistance to swelling)
- more resistant to bending and
- harder and more abrasion-resistant than conventional plastics.
Electron beams consist of electrons (negatively charged elementary particles) that move in a single direction at the same speed along a line. They are generated in a vacuum using high voltage with a heated cathode. This process can be compared with the cathode ray tube (CRT) of a television in which the electrons are accelerated by an electrostatic field.
In our case the acceleration takes place in a vacuum of 10-6 Pascal. Depending on the system, the electrons are accelerated in a straight acceleration channel through an electromagnetic field (linear accelerator) or in a circular movement (rhodotron) and then diverted to the item to be treated. The fast-moving electrons are also known as beta rays.
When the beta rays impact on the product, electrons are released from the atoms of the treated material. These secondary electrons cause a variety of effects: On the one hand the DNA and cell membranes of micro-organisms change, thus leading to cell death (sterilisation), while on the other they contribute to the formation of more highly reactive ions and free radicals, which, for their part, react with each other and with the contents of the treated material, causing the crosslinking of the molecules.
Crosslinking process: From thermoplastics to thermosets
Thermoplastic materials consist of long, smooth chains of molecules that start to move when heat is applied, sliding past each other and increasingly losing their cohesiveness. The plastic becomes soft and melts.
Due to the energy of the electron beams used, which is absorbed in the plastic, so-called “radicals” are formed that react with one another chemically and form a link between the chains of molecules. Crosslinking takes place, joining the molecules together and considerably restricting their movements. Thus, the plastic changes to a thermoset from a thermoplastic state. Even when increased heat is applied it remains largely dimensionally stable and can no longer melt.