Pure Polyethylene Neutron Shielding

JCPEP

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
Moderation
Medical Applications

The JCS borated neutron shielding assembly
The JCS borated neutron shielding assembly
Method Units Values
Properties
Colour - - White, Black, colours
Density ISO 1183-1 g/cm³ 0.96
Thermal Properties
Melting temperature (DSC, 10°C (50°F) / min) ISO 11357-1/-3 °C 135
Glass transition temperature (DSC, 20°C (68°F) / min) ISO 11357-1/-2 °C -
Thermal conductivity at 23°C (73°F) - W/(K.m) 0.4
Coefficient of linear thermal expansion (-40 to 150 °C) (-40 to 300°F) ASTM E-831 (TMA) µin./in./°F
Coefficient of linear thermal expansion (23 to 100°C) (73°F to 210°F) - µm/(m.K) 150
Heat Deflection Temperature: method A: 1.8 MPa (264 PSI) ISO 75-1/-2 °C 44
Continuous allowable service temperature in air (20.000 hrs) - °C 80
Min. service temperature - °C -100
Flammability: UL 94 (3 mm (1/8 in.)) - - HB
Flammability: Oxygen Index ISO 4589-1/-2 % <20
Mechanical Properties
Tensile strength ISO 527-1/-2 MPa 28
Tensile strain (elongation) at yield ISO 527-1/-2 % 10
Tensile strain (elongation) at break ISO 527-1/-2 % > 50
Tensile modulus of elasticity ISO 527-1/-2 MPa 1300
Shear Strength ASTM D732 MPa
Compressive stress at 1 / 2 / 5 % nominal strain ISO 604 MPa 12 / 18.5 / 26.5
Compressive strength ASTM D695 PSI -
Charpy impact strength - unnotched ISO 179-1/1eU kJ/m² no break
Charpy impact strength - notched ISO 179-1/1eA kJ/m² 105P
Charpy impact strength - double 14° notched ISO 11542-2 kJ/m² 25
Izod Impact notched ASTM D256 ft.lb./in
Flexural strength ISO 178 MPa 27
Flexural modulus of elasticity ISO 178 MPa -
Relative volume loss during wear test "sand-slurry" : TIVAR® 1000=100 ISO 15527 - 350
Shore hardness D ISO 868 - 62
Electric strength IEC 60243-1 kV/mm 45
Electrical Properties
Volume resistivity IEC 62631-3-1 Ohm.cm 10E13
Surface resistivity ANSI/ESD STM 11.11 Ohm/sq. 10E12
Dielectric constant at 1 MHz IEC 62631-2-1 - -
Dissipation factor at 1 MHz IEC 62631-2-1 - -
Miscellaneous
Specific Gravity ASTM D792 - -
Water absorption after 24h immersion in water of 23°C (73°F) ISO 62 % < 0.1
Water absorption at saturation in water of 23 °C (73°F) - % < 0.1
Wear rate ISO 7148-2 µm/km 300
Dynamic Coefficient of Friction (-) ISO 7148-2 - 0.15-0.30
Limiting PV at 100 FPM QTM 55007 ft.lbs/in².min -
Limiting PV at 0.1 / 1 m/s cylindrical sleeve bearings - Mpa.m/s 0.08 / 0.05
Note: 1 g/cm³ = 1,000 kg/m³ ; 1 MPa = 1 N/mm² ; 1 kV/mm = 1 MV/m
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