Champlain Irradiation Brochure
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The polymers used for the insulation of wire and conductors are long chains of molecules. Each molecule is a specific chemical group. The simplest polymer is polyethylene consisting of a carbon and two hydrogen atoms. i.e. CH2 The figure below is a representation of polyethylene. The chains intermesh in a random manner. Polyethylene is tough, flexible and relatively inexpensive but when heat is applied the chains are free to slip and slide. The polyethylene will soften and melt when heat is applied. Hence it is classified a thermoplastic compound.
The primary object of irradiation cross-linking is to reduce molecular slipping by introducing cross-linking bonds between nearby chains. Cross- linking improves the rigidity and increases the temperature resistance. Irradiation cross-linking uses a stream of fast moving electrons produced from an electron accelerator. The electrons possess sufficient energy to remove a hydrogen atom from its position along a chain leaving a highly reactive site or vacancy. This site, called a free radical, may combine with another such site to form a cross-link as shown in the figure below. The formation of a sufficient number of these cross-links results in transforming a thermal plastic material (one that melts) to a thermoset material (does not melt).
Cross-linked Polyethylene
Features of Cross-Linked Polymers
- Higher temperature resistance
- No melting
- Increased tensile strength
- Increased abrasion and cut through resistance
- Increased crush resistance
- Increased chemical and oil resistance
- Increased shear and compressive strength
Industrial Solutions for Cross-Linking
- Peroxide-Method
- Silane-Method
- Irradiation Method
In contrast to the other technologies, the irradiation cross-linking does not require heat, pressure or moisture. Therefore irradiation leaves no unreacted curing agents that can create harmful acids at elevated temperatures. Superior cut and stripping is possible because irradiation cross-linking does not require heat and pressure that can force compound between the wire strands. Furthermore with irradiation is is also possible to cross-link a wider range of compounds and subsequently produce superior cables than chemical cross-linking.
Compounds cross-linkable with Irradiation
- EPDM
- Halar
- Hypalon
- Kynar
- Neoprene
- Nordel
- Nylon
- Polyethylene
- Polyurethane
- PVC
- Silicone
- Tefzel
- Tyvrin
- Vamac
- Viton
Last Modification Freitag, 7. Mai 2010 at 22:30:53