Pure Polyethylene Neutron Shielding


JCPEP is a pure, high molecular weight, polyethylene neutron shielding, frequently used as a moderator where it is desired to slow fast neutrons down to thermal energies for experimentation.

In these applications, it is highly desirable to maximise the hydrogen content and minimise any impurities, especially those that might absorb neutrons. We can supply high purity virgin polyethylene for this application in a variety of shapes and sizes.

JCPEP can be readily machined into complex shapes for applications involving neutron instrumentation, reactor physics, activation analysis or isotopic neutron sources. John Caunt Scientific can not only provide custom machining but can also pour JCPEP into custom-made moulds to provide application-specific shielding form.

Used to thermalise fast neutrons
An excellent neutron moderator with very high hydrogen content
Available as slabs, bricks, pellets, rods and spheres
Other dimensions/shapes on request
Can be supplied machined to close tolerances

Linac Bunkers
Medical Applications

The JCS borated neutron shielding assembly
The JCS borated neutron shielding assembly
Material designation JCPEP
ISO designation PE-HMW
Table Group 3
Material description High Molecular Weight
Polyethylene (virgin)
Colour(s) natural, green, blue, yellow, red, black
Material properties Standard Unit
Average molecular weight (average molecular mass) (g/mol) approx. 0,5 * 10⁶
Density ISO 1183 (kg/m²) 950-957
Water absorption at 23° C until saturation ISO 62 (~) < 0,01
Mechanical properties Standard Unit
Tensile stress at yield (tensile strength) ISO 527 (MPa) > 20
Elongation at break ISO 527 (~) > 450
Tensile modulus ISO 527 (MPa) 800
Impact strength (Charpy) at 23° C ISO 179 (kJ/m²) no break
Notched impact strength (Charpy) at 23° C ISO 11542-2 (kJ/m²) > 15
Ball indentation hardness ISO 2039-1 (N/mm²) 32-38
Shore-Hardness D, 15 s value ISO 868 (~) 62-68
Coefficient of friction (~) approx. 0,25
Abrasion (Sand-Slurry) (~) < 400
Themal properties Standard Unit
Melting point DSC, 10 K/min ISO 3146 (°C) 135-138
Vicat softening point ISO 306 (°C) 79
Coefficient of linear themal expansion between 23 and 80° C ISO 11359 (K-1) approx. 2 * 10⁻⁴
Themal conductivity ISO 52612 (W/[m * K]) approx. 0,4
Use temperature (max.) (°C) 80
Use temperature (briefly) (°C) 90
Use temperature (min.) (°C) -30
Electrical propertiess Standard Unit
Relative permitivity at 100 Hz IEC 60250 (-) 2,9
Dissipation factor at 100 Hz IEC 60250 (-) 2,1 *10⁻⁴
Volume resistivity IEC 60093 (Ohm * m) >10¹²
Surface resistivity IEC 60093 (Ohm) >10¹²
Dielectric strength IEC 60243 (kV/mm) 40
Physiological properties Standard Unit
Food conformances according to
EU Directive 2002/72/EC yes
FDA Regulation 21 CFR1 77.1520 yes
FDA Regulation 21CFR178.2010 N/A
FDA Regulation 21 CFR1 78.3297 yes
Get in touch with The JCS team