| Cross Linked Polyethylene (XLPE) |
|
| Plastic Type | Thermoset |
| Melting Temp. | 150-170 0C |
| Density | 0,93 g/cm3 |
| Tensile Strength |
18 MPa |
| Dielectric constant | 2,2@1MHz |
| Resistance (ohm.cm) |
1018 |
Polyethylene was cross linked
for the first time in 1930 with electron beam technology. "Engel" cross-linking
was developed in 1960's. Using vinylsilane was developed in 1986.
Polyethylene (PE) is one of the most common thermoplastic that used in cable
production. Cross-linked
Polyethylene is abbreviated either XLPE or PEX. In cable production XLPE
is more common. PE has good electrical properties and a high electric resistivity,
that gives it potential for use at much higher voltages than PVC.
Plus, cross-linking results in better mechanical properties which makes XLPE
the most compatible for cable types rated over 0,6/1 kV and higher.
After cross linking XLPE would not melt down anymore. By cross linking
process, thermoplastic PE
changed into thermoset XLPE. Meanwhile, Abrasion resistance, impact
strength, thermal stability, tensile strength and scratch resistance would be
enhanced significantly.
There are
a few different ways to cross link polyethylene. Cross-links can be
formed by chemical reactions that are initiated by heat, pressure, change in
pH, or irradiation. For example, mixing of an unpolymerized or partially
polymerized resin with specific chemicals called crosslinking reagents results
in a chemical reaction that forms cross-links. Cross-linking can also be
induced in materials that are normally thermoplastic through exposure to a
radiation source, such as electron beam exposure, gamma radiation, or UV
light. For example, electron beam processing is used to cross-link the C type
of cross-linked polyethylene. Other types of cross-linked polyethylene are
made by addition of peroxide during extruding (type A) or by addition of a
cross-linking agent (e.g. vinylsilane) and a catalyst during extruding and
then performing a post-extrusion curing.1
References:
wikipedia.org/wiki/Cross-linked_polyethylene
http://electrical-engineering-portal.com/