PE-X (polyethylene cross-linked, molding)

Designation

Crosslinked polyethylene / XLPE / PEX (Molding)

Tradenames

Borealis, Borlink, Dow Electrical Telecommunications, Endurance, Getilan, Hyundai, Icorene, Kafrit, LNP Lubricomp, LNP Stat-Kon, Polidan, Polylink, Polylink Power, Schulink, Superclean, Supercopo, Supercure, Supersmooth, Supertr, Syncure, Visico

Typical uses

Cable covering, shrink-wrap film, heat-shrinkable tubing, pipe for domestic heating systems, rotationally molded tanks.

Compositional summary

(CH2-CH2)n with a high degree of cross-linking by one of four methods. (A) peroxide, C-C cross-links; (B) silane, C-Si-O-Si-C cross-links; (C) electron beam processing; (D) azo (nitrogen) cross-links.

Material family	Plastic (thermoplastic, semi-crystalline)
Base material	PE-X (Polyethylene, crosslinked)
Polymer code	PE-X

Composition detail

Polymer

100

Physical properties

Density

0.92

–

1.24

g/cm³

Mechanical properties

Young’s modulus	1	–	1.4	GPa
Specific stiffness	0.891	–	1.38	MN.m/kg
Yield strength (elastic limit)	18	–	20	MPa
Tensile strength	20	–	31.7	MPa
Specific strength	15.2	–	20.8	kN.m/kg
Elongation	10	–	440	% strain
Compressive modulus	0.7	–	1	GPa
Compressive strength	17.3	–	37.9	MPa
Flexural modulus	0.7	–	2	GPa
Flexural strength (modulus of rupture)	20.4	–	44.8	MPa
Shear modulus	0.695	–	0.73	GPa
Bulk modulus	2	–	2.1	GPa
Poisson’s ratio	0.396	–	0.412
Shape factor	6
Hardness – Vickers	5	–	6	HV
Elastic stored energy (springs)	125	–	184	kJ/m³
Fatigue strength at 10^7 cycles	8	–	12.7	MPa

Impact & fracture properties

Fracture toughness	0.886	–	2.66	MPa.m^0.5
Toughness (G)	0.804	–	4.92	kJ/m²
Impact strength, notched 23 °C	5.3	–	110	kJ/m²

Thermal properties

Melting point	102	–	177	°C
Glass temperature	-125	–	-90	°C
Heat deflection temperature 0.45MPa	54	–	107	°C
Heat deflection temperature 1.8MPa	41	–	63	°C
Maximum service temperature	90	–	110	°C
Minimum service temperature	-81	–	-71	°C
Thermal conductivity	0.214	–	0.222	W/m.°C
Specific heat capacity	1.56e3	–	1.62e3	J/kg.°C
Thermal expansion coefficient	176	–	184	µstrain/°C
Thermal shock resistance	74.7	–	106	°C
Thermal distortion resistance	0.00118	–	0.00124	MW/m

Electrical properties

Electrical resistivity	2.37e23	–	2.13e24	µohm.cm
Electrical conductivity	8.08e-23	–	7.27e-22	%IACS
Dielectric constant (relative permittivity)	2	–	2.2
Dissipation factor (dielectric loss tangent)	1e-4	–	7e-4
Dielectric strength (dielectric breakdown)	9.06	–	21.7	MV/m

Magnetic properties

Magnetic type

Non-magnetic

Optical, aesthetic and acoustic properties

Transparency	Translucent
Acoustic velocity	938	–	1180	m/s
Mechanical loss coefficient (tan delta)	0.0286	–	0.04

Absorption & permeability

Water absorption @ 24 hrs

0.01

–

0.06

Processing properties

Polymer injection molding	Acceptable
Polymer extrusion	Acceptable
Polymer thermoforming	Unsuitable
Linear mold shrinkage	2	–	5	%
Melt temperature	77	–	149	°C
Mold temperature	30	–	50	°C
Molding pressure range	70	–	140	MPa

Durability

Water (fresh)	Acceptable
Water (salt)	Acceptable
Weak acids	Acceptable
Strong acids	Acceptable
Weak alkalis	Acceptable
Strong alkalis	Acceptable
Organic solvents	Limited use
Oxidation at 500C	Unacceptable
UV radiation (sunlight)	Fair
Flammability	Highly flammable