spore: profile
id: borated-polyethylene
spore_version: 0.2
family: polyolefins
name: Borated polyethylene
abbreviation: BPE
role: neutron shield
category: shielding
type: hydrogen-rich-polymers
summary: |
  Borated polyethylene is polyethylene loaded with boron, at 5 % boron by weight in the grades read, for neutron shielding. JCS Nuclear Solutions' JCPE5 (5 % boron, HMW grade) has a density of 1.04 g/cm3 (ISO 1183-1) and a melting temperature of 135 °C (ISO 11357-1/-3). MarShield's borated polyethylene is printed as 1.01 g/cc (ASTM D792) with a melting point of 128 °C (ASTM D3418), so the two datasheets differ. In a preliminary 2009 NASA proton test, boron-polyethylene at 5.35 g/cm2 gave 2.10 µGy per spill, against 2.11 µGy per spill for neat HDPE at 5.52 g/cm2, so no clear boron benefit showed at those thicknesses.
best_for: Neutron shielding where the temperature stays low, such as vault doors, containers and nuclear shields (5 % boron grade, density 1.04 g/cm3 per JCPE5)
weakest_at: 'Heat under load: heat deflection at 1.8 MPa is 45 °C (JCPE5) and 46.7 °C (MarShield), and continuous service is rated to 80 °C in air'
identity:
  formula: (C2H4)n polyethylene with a boron filler, 5 % boron by weight in the grades read
  source: wikipedia-polyethylene
  where: Introduction and infobox, chemical formula (C2H4)n; boron content from the MarShield data sheet first page and the JCPE5 page
tags:
  environments: []
  stresses:
    - total-radiation-dose
    - extreme-cold
    - extreme-heat
  applications:
    - radiation-shielding
properties:
  - benchmark: density
    label: Density, JCPE5 5 % borated polyethylene
    value: 1.04
    unit: g/cm3
    scope: material
    conditions:
      grade: JCPE5, 5 % boron loaded, HMW grade
      standard: ISO 1183-1 as printed
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Specifications table, Density row
  - benchmark: melting_point
    label: Melting temperature, JCPE5
    value: 135
    unit: °C
    scope: material
    conditions:
      grade: JCPE5
      test: DSC, 10 °C (50 °F) per minute, ISO 11357-1/-3 as printed
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, Melting temperature row
  - benchmark: heat_deflection_temperature
    label: Heat deflection temperature, JCPE5
    value: 45
    unit: °C
    scope: material
    conditions:
      load: 1.8 MPa (264 PSI), method A
      standard: ISO 75-1/-2 as printed
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, Heat Deflection Temperature method A row
  - benchmark: max_service_temp
    label: Continuous allowable service temperature in air, JCPE5
    value: 80
    unit: °C
    scope: material
    conditions:
      duration: 20,000 h in air, as printed (20.000 hrs)
    method: Rating printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, Continuous allowable service temperature in air row
  - benchmark: min_service_temp
    label: Minimum service temperature, JCPE5
    value: -20
    unit: °C
    scope: material
    conditions:
      basis: minimum service temperature as printed, no test printed
    method: Rating printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, Min. service temperature row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, JCPE5
    value: 0.38
    unit: W/(K.m)
    scope: material
    conditions:
      temperature: 23 °C (73 °F)
      bound: printed as ≥ 0.38, so this is a minimum
    method: Typical value printed on the manufacturer product page; no test standard printed
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, Thermal conductivity at 23 °C row
  - benchmark: cte
    label: Coefficient of linear thermal expansion, JCPE5
    value: 135
    unit: µm/(m.K)
    scope: material
    conditions:
      temperature_range: 23 to 100 °C (73 °F to 210 °F)
    method: Value printed on the manufacturer product page; no test standard printed
    status: ground
    source: jc-jcpe5
    where: Thermal Properties table, CTE 23 to 100 °C row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, JCPE5
    value: 21
    unit: MPa
    scope: material
    conditions:
      standard: ISO 527-1/-2 as printed
      specimen: not printed
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Mechanical Properties table, Tensile strength row
  - benchmark: elongation
    label: Tensile strain at break, JCPE5
    value: 7
    unit: '%'
    scope: material
    conditions:
      standard: ISO 527-1/-2 as printed
      type: at break, as printed (the page also prints 7 % at yield)
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Mechanical Properties table, Tensile strain (elongation) at break row
  - benchmark: elastic_modulus
    label: Tensile modulus of elasticity, JCPE5
    value: 1600
    unit: MPa
    scope: material
    conditions:
      standard: ISO 527-1/-2 as printed
    method: Typical value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Mechanical Properties table, Tensile modulus of elasticity row
  - benchmark: moisture_absorption
    label: Water absorption after 24 h immersion, JCPE5
    value: 0.1
    unit: '%'
    scope: material
    conditions:
      duration: 24 h immersion
      temperature: 23 °C (73 °F)
      bound: printed as < 0.1, so this is an upper limit
      standard: ISO 62 as printed
    method: Value printed on the manufacturer product page
    status: ground
    source: jc-jcpe5
    where: Miscellaneous table, Water absorption after 24h immersion row
  - benchmark: density
    label: Specific gravity, MarShield borated polyethylene
    value: 1.01
    unit: g/cc
    scope: material
    conditions:
      standard: ASTM D792 as printed
      grade: Borated polyethylene, MarShield data sheet N-BP-0616, 5 % boron by weight (brochure page)
    method: Typical value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Physical Properties table, Specific Gravity row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, MarShield borated polyethylene
    value: 16.6
    unit: MPa
    scope: material
    conditions:
      standard: ASTM D638 as printed
      grade: MarShield borated polyethylene
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Tensile Strength row
  - benchmark: elastic_modulus
    label: Tensile modulus, MarShield borated polyethylene
    value: 0.7667
    unit: GPa
    scope: material
    conditions:
      standard: ASTM D638 as printed
      grade: MarShield borated polyethylene
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Tensile Modulas row (printed spelling)
  - benchmark: flexural_strength
    label: Flexural yield strength, MarShield borated polyethylene
    value: 29.1
    unit: MPa
    scope: material
    conditions:
      standard: ASTM D790 as printed
      grade: MarShield borated polyethylene
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Flexural Yield Strength row
  - benchmark: flexural_modulus
    label: Flexural modulus, MarShield borated polyethylene
    value: 0.8729
    unit: GPa
    scope: material
    conditions:
      standard: ASTM D790 as printed
      grade: MarShield borated polyethylene
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Flexural Modulas row (printed spelling)
  - benchmark: elongation
    label: Elongation at break, MarShield borated polyethylene
    value: 4
    unit: '%'
    scope: material
    conditions:
      standard: ASTM D638 as printed
      grade: MarShield borated polyethylene
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Elongation at Break row
  - benchmark: cte
    label: Linear CTE, MarShield borated polyethylene
    value: 198
    unit: µm/m-°C
    scope: material
    conditions:
      temperature_range: '-40 to 150 °C as printed (-40 to 302 °F)'
      standard: ASTM E831 as printed
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Thermal Properties table, CTE linear row
  - benchmark: melting_point
    label: Melting point, MarShield borated polyethylene
    value: 128
    unit: °C
    scope: material
    conditions:
      standard: ASTM D3418 as printed
      grade: MarShield borated polyethylene
    method: Printed on the data sheet as 128C °C; the value is recorded as 128 °C
    status: ground
    source: marshield-bpe
    where: Thermal Properties table, Melting Point row
  - benchmark: heat_deflection_temperature
    label: Heat deflection temperature, MarShield borated polyethylene
    value: 46.7
    unit: °C
    scope: material
    conditions:
      load: 1.8 MPa (264 psi)
      standard: ASTM D648 as printed
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Thermal Properties table, Deflection Temperature at 1.8 MPa row
  - benchmark: izod_impact_notched
    label: Izod impact, notched, MarShield borated polyethylene
    value: 0.481
    unit: J/cm
    scope: material
    conditions:
      standard: ASTM D256 as printed
      specimen: notched
    method: Value printed on the manufacturer data sheet, which also prints 0.900 ft-lb/in
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Izod Impact Notched row
  - benchmark: hardness_shore_d
    label: Hardness, Shore D, MarShield borated polyethylene
    value: 71
    unit: '-'
    scope: material
    conditions:
      standard: ASTM D2240 as printed
      scale: Shore D
    method: Value printed on the manufacturer data sheet
    status: ground
    source: marshield-bpe
    where: Mechanical Properties table, Hardness Shore D row
  - benchmark: absorbed_dose_per_spill
    label: Absorbed dose per spill, boron-polyethylene at 5.35 g/cm2 (preliminary)
    value: 2.1
    unit: µGy/Spill
    scope: material
    conditions:
      beam: 190 MeV protons, Loma Linda University Medical Center proton synchrotron
      areal_density: 5.35 g/cm2
      sample: boron-doped polyethylene as described in the Figure 7 caption (94.5 % polyethylene, 5.5 % boron)
    method: Tissue equivalent proportional counter measurement, preliminary; instrument error about 8 % as printed
    status: ground
    source: rojdev-2009-nasa
    where: Table 1, row Boron -Poly 5.35
  - benchmark: absorbed_dose_per_spill
    label: Absorbed dose per spill, neat HDPE at 5.52 g/cm2 (comparison)
    value: 2.11
    unit: µGy/Spill
    scope: material
    conditions:
      beam: 190 MeV protons, Loma Linda University Medical Center proton synchrotron
      areal_density: 5.52 g/cm2
    method: Tissue equivalent proportional counter measurement, preliminary
    status: ground
    source: rojdev-2009-nasa
    where: Table 1, row HDPE 5.52
  - benchmark: dose_equivalent_per_spill
    label: Dose equivalent per spill, boron-polyethylene at 5.35 g/cm2 (preliminary)
    value: 3.31
    unit: µSv/Spill
    scope: material
    conditions:
      beam: 190 MeV protons, Loma Linda University Medical Center proton synchrotron
      areal_density: 5.35 g/cm2
    method: Tissue equivalent proportional counter measurement, preliminary
    status: ground
    source: rojdev-2009-nasa
    where: Table 1, row Boron -Poly 5.35, Dose Equivalent column
corrosion:
  - environment: Continuous sunlight
    headline: MarShield rates continuous sunlight as Limited for its borated polyethylene.
    effect: The chemical resistance table gives continuous sunlight as Limited. The table prints no UV exposure time, dose or retention figure.
    conditions:
      basis: qualitative rating in the chemical resistance table; no test method printed
    source: marshield-bpe
    where: Chemical Resistance Properties table, Continuous Sunlight row
    rating: unknown
  - environment: Hot water or steam
    headline: MarShield rates hot water and steam as Limited for borated polyethylene.
    effect: The chemical resistance table gives hot water and steam as Limited, with no temperature or time printed.
    conditions:
      basis: qualitative rating; no test method printed
    source: marshield-bpe
    where: Chemical Resistance Properties table, Hot Water / Steam row
    rating: unknown
  - environment: Chlorinated solvents, aliphatic and aromatic hydrocarbons, ketones and esters
    headline: MarShield rates chlorinated solvents, hydrocarbons, ketones and esters as Unacceptable.
    effect: The same table rates strong and weak acids, strong and weak alkalies, alcohols and inorganic salt solutions as Acceptable. Chlorinated solvents, aliphatic and aromatic hydrocarbons, and ketones and esters are rated Unacceptable.
    conditions:
      basis: qualitative rating; no concentration or temperature printed
    source: marshield-bpe
    where: Chemical Resistance Properties table, rows Chlorinated Solvents, Hydrocarbons and Ketones, Esters
    rating: unknown
  - environment: Heat in service
    headline: JCPE5 is rated to 80 °C continuous in air for 20,000 hours.
    effect: Under a 1.8 MPa load the material softens at 45 °C (JCPE5) or 46.7 °C (MarShield), so the continuous rating is well below the melting point of 128 to 135 °C.
    conditions:
      basis: manufacturer rating in air; the load case is the heat deflection test at 1.8 MPa
    source: jc-jcpe5
    where: Thermal Properties table, Continuous allowable service temperature in air row and Heat Deflection Temperature row
    rating: unknown
  - environment: Cold
    headline: JCPE5 gives -20 °C as its minimum service temperature.
    effect: No low-temperature impact or brittleness test for borated polyethylene was read in these sources, so the -20 °C rating is the manufacturer's only cold figure.
    conditions:
      basis: manufacturer rating; no test printed
    source: jc-jcpe5
    where: Thermal Properties table, Min. service temperature row
    rating: unknown
risks:
  hazards:
    - text: 'Boron filler: the Materion SDS for elemental boron (boron pieces, CAS 7440-42-8, 100 %) says the substance does not meet GHS classification criteria, and that dust may irritate the respiratory tract, skin and eyes. That SDS covers pure boron, not the borated polyethylene.'
      ghs: []
      source: materion-boron-sds
      where: Sections 2 (hazards identification), 3 (composition) and the toxicological section
    - text: 'Base polyethylene: the Borouge Borcoat HE3450 safety information sheet gives the product as not hazardous under SS 586: Part 2: 2022 (GHS, Singapore adaptation), with pictograms, signal word and hazard statements all printed as Nil. It notes that dust can irritate the respiratory tract and, mixed with air in critical proportions, can form a dust explosion risk.'
      ghs: []
      source: borouge-he3450-sds
      where: Section 2 (hazards identification) and the fire-fighting text
  failure_risks:
    - mode: Softening under sustained load
      trigger: A load-bearing shield held above about 45 °C under sustained load
      consequence: Deformation at 1.8 MPa is the only load case in the sources read; no creep or long-term load test was read, so the consequence is not quantified.
      severity: moderate
      source: jc-jcpe5
      where: Thermal Properties table, Heat Deflection Temperature row
    - mode: Lower dose benefit than expected from the boron
      trigger: Preliminary proton-beam test at 190 MeV on boron-polyethylene samples at 5.35 g/cm2
      consequence: The boron sample gave 2.10 µGy per spill against 2.11 µGy per spill for neat HDPE at 5.52 g/cm2. NASA reports similar performance to neat polyethylene and aluminium at comparable thickness, and says ground data were not final.
      severity: moderate
      source: rojdev-2009-nasa
      where: Table 1 and Preliminary Results text
  side_effects: []
  handling:
    - text: MarShield says the standard 48 x 96 x 1 inch sheet can be cut with standard woodworking tools; no handling hazard is printed on that data sheet.
      source: marshield-bpe
    - text: Keep dust down when machining. The boron SDS advises minimising dust generation and using exhaust ventilation where dust forms.
      source: materion-boron-sds
    - text: Dust from the base polyethylene can irritate the respiratory tract, and the Borouge sheet notes a dust explosion risk in air at critical proportions.
      source: borouge-he3450-sds
  mitigations: []
uses:
  - application: radiation-shielding
    device: Neutron shield sheets, vault doors and storage containers
    example: MarShield lists medical vaults and doors, particle accelerators, hot cells, nuclear storage and transport containers, and nuclear detection systems as uses of its borated polyethylene.
    source: marshield-bpe
    where: Opening text, first page of the borated polyethylene data sheet
  - application: radiation-shielding
    device: Neutron shield in nuclear installations (JCPE5)
    example: JCS Nuclear Solutions describes JCPE5 as a 5 % boron loaded polyethylene neutron shield, developed for nuclear installations where low and intermediate neutron flux is expected and elevated temperatures are not.
    source: jc-jcpe5
    where: Product description text
  - application: radiation-shielding
    device: Space radiation shield, preliminary study
    example: NASA's 2009 study tested boron-polyethylene in a 190 MeV proton beam and modelled thicker samples. In simulation, the 5 % borated grade was a better mitigator than the 0.86 % and 30 % grades, but the ground data were preliminary.
    source: rojdev-2009-nasa
    where: Figure 1 text and Summary
supply:
  - subject: Boron (filler element and borate feedstock)
    demand: 'USGS 2025 production, thousand metric tons, all forms: Turkey refined borates 1,500; Bolivia ulexite 380; Chile ulexite 300; China boric oxide equivalent 230; Peru crude borates 220; Argentina crude ore 170; Russia datolite ore 80; Germany compounds 40; US production withheld (W).'
    routes: Boron does not occur in nature as the element. USGS says it is mined as borates and processed to boric acid or borate salts, and boron products are priced by boric oxide (B2O3) content.
    producers: []
    critical_lists:
      - list: USGS 2025 critical minerals list, boron added (USGS Mineral Commodity Summaries 2026)
        listed: true
    substitutes: []
    source: usgs-mcs2026-boron
    where: World Production and Reserves table, 2025 column; Events, Trends and Issues; Import Sources line
    abundance: 'USGS reserves printed in thousand metric tons: Turkey 950,000; Chile 35,000; Russia 40,000; China 9,100; Peru 4,000; United States 48,000.'
  - subject: Boron (US import sources)
    demand: 'Import sources for all boron forms, 2021 to 2024: Turkey 90 %, Bolivia 6 %, other 4 % (USGS). The basis (value or weight) is not printed.'
    producers: []
    critical_lists: []
    substitutes: []
    source: usgs-mcs2026-boron
    where: Imports for consumption, Import Sources line
documents:
  - title: 5% Borated Polyethylene (JCPE5), JCS Nuclear Solutions product page
    type: datasheet
    url: https://johncaunt.com/products/jcpe5/
    year: 2026
  - title: Borated Polyethylene, Neutron Shielding, MarShield data sheet N-BP-0616
    type: datasheet
    url: https://marshield.com/publications/Nuclear_BoratedPolyethylene.pdf
  - title: Evaluation of Multi-Functional Materials for Deep Space Radiation Shielding (Rojdev, Atwell, Wilkins, Gersey, Badavi), NTRS 20090020691
    type: report
    url: https://ntrs.nasa.gov/api/citations/20090020691/downloads/20090020691.pdf
    year: 2009
  - title: 'USGS Mineral Commodity Summaries 2026: Boron'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
  - title: Materion Safety Data Sheet, Boron pieces (SDS B-MSDS0071, revision 07-14-2015)
    type: sds
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/boron%20%20-%20Materion..pdf
    year: 2015
  - title: Borouge Borcoat HE3450 safety information sheet (polyethylene)
    type: sds
    url: https://www.borouge.com/en/e-service/DataSheets/Borcoat%20HE3450/HE3450_SIS.pdf
  - title: NIST Atomic Weights and Isotopic Compositions for All Elements
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=B&all=all&ascii=html
gaps:
  - No safety data sheet for the 5 % borated polyethylene product was read. The hazard entries use an elemental boron SDS (Materion) and a base polyethylene SDS (Borouge), which are different products.
  - No neutron capture cross-section, neutron attenuation coefficient or half-value thickness for any borated grade was found. NASA gives proton dose only.
  - No source read names the boron compound in the commercial grades. JCPE5 says only the added boron compound absorbs the neutrons.
  - Radiation ageing of borated polyethylene (gamma, neutron, or long UV exposure) was not found. The only sunlight rating is MarShield's Limited, with no test figure.
  - Environment tags (lunar-day, deep-space) are left empty. The NASA paper discusses lunar surface and deep-space cases but gives no test condition tied to the product.
  - Production and producers of the base polyethylene were not found in a source read for this profile.
  - JCPE5 Charpy impact values are printed unclearly (15,0 and 5C) and are left out. Izod, flexural strength and flexural modulus are printed as dashes on the JCPE5 page.
  - MarShield's chemical resistance is qualitative (Acceptable, Limited, Unacceptable). No numeric exposure test was printed.
  - Notched Izod impact, Shore D hardness, and absorbed dose or dose equivalent per spill use snake_case names that are not in the property canon.
  - 'The NASA dose values are preliminary: one 190 MeV proton beam, TEPC error about 8 %, the Li-polyethylene target corrupted, and the boron coupons were 5.5 % boron per the Figure 7 caption, not the 5 % commercial grade.'
  - JCPE5 (1.04 g/cm3, 135 °C) and MarShield (1.01 g/cc, 128 °C) differ on density and melting point. Both values are recorded and not averaged.
  - No low-temperature brittleness, outgassing or atomic oxygen erosion value for borated polyethylene was found.
  - Volume resistivity of JCPE5 (printed 10E13) and surface resistivity of MarShield (printed >= 1.0e+12 ohm) are left out because the printed form could not be matched to a plain number in the source check.
sources:
  jc-jcpe5:
    title: 5% Borated Polyethylene (JCPE5), JCS Nuclear Solutions product page, Specifications table
    id: Product page, Specifications table
    url: https://johncaunt.com/products/jcpe5/
    year: 2026
    kind: datasheet
    license: manufacturer web page, linked not reproduced
  marshield-bpe:
    title: Borated Polyethylene, Neutron Shielding, MarShield data sheet N-BP-0616
    id: N-BP-0616, physical, mechanical, thermal, electrical and chemical resistance tables
    url: https://marshield.com/publications/Nuclear_BoratedPolyethylene.pdf
    kind: datasheet
    license: manufacturer data sheet, linked not reproduced
  rojdev-2009-nasa:
    title: Evaluation of Multi-Functional Materials for Deep Space Radiation Shielding
    id: Rojdev, Atwell, Wilkins, Gersey and Badavi; NTRS 20090020691; 2009 NSMMS
    url: https://ntrs.nasa.gov/api/citations/20090020691/downloads/20090020691.pdf
    year: 2009
    kind: report
    license: NASA public document
  usgs-mcs2026-boron:
    title: 'Mineral Commodity Summaries 2026: Boron (U.S. Geological Survey)'
    id: mcs2026-boron, World Production and Reserves table, Events, Trends and Issues
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
    kind: report
    license: US government publication
  materion-boron-sds:
    title: Safety Data Sheet, Boron pieces, Materion Advanced Chemicals
    id: SDS B-MSDS0071, version 02, revision 07-14-2015
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/boron%20%20-%20Materion..pdf
    year: 2015
    kind: datasheet
    license: supplier SDS, linked not reproduced
  borouge-he3450-sds:
    title: Borcoat HE3450 safety information sheet, Borouge (polyethylene)
    id: SIS, polyethylene; GHS classification under SS 586 Part 2 (2022) as printed
    url: https://www.borouge.com/en/e-service/DataSheets/Borcoat%20HE3450/HE3450_SIS.pdf
    kind: datasheet
    license: supplier SDS, linked not reproduced
  nist-atomic-weights:
    title: NIST Atomic Weights and Isotopic Compositions for All Elements (H, B and C rows)
    id: 'Standard atomic weight intervals as printed: H [1.007 84, 1.008 11]; B [10.806, 10.821]; C [12.0096, 12.0116]'
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=B&all=all&ascii=html
    kind: database
    license: US government data
  wikipedia-polyethylene:
    title: Polyethylene, Wikipedia
    id: 'Introduction and infobox: chemical formula (C2H4)n; Manufacturing process, monomer ethylene C2H4'
    url: https://en.wikipedia.org/wiki/Polyethylene
    kind: web
    license: CC BY-SA 4.0, linked not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 25
  unreachable: 0
  caveats: 6
  note: 'Values read by an AI assistant on 2026-11-01 from the pages named in each entry. The Marshield and NASA PDFs were read as text with pdftotext. JCPE5 values were confirmed in the page HTML. Caveats: JCPE5 and MarShield differ on density, melting point, tensile strength and HDT; the NASA dose values are preliminary and from a 5.5 % boron coupon; the Marshield data sheet prints no grade name; no SDS for the 5 % borated product was read; the JCPE5 volume resistivity and MarShield surface resistivity were dropped after the value check.'
story:
  recipe:
    line: Borated polyethylene is polyethylene, (C2H4)n, made from ethylene, with a boron filler. The grades read carry 5 % boron by weight (MarShield and JCPE5). The sources do not name the boron compound, so the recipe lists boron as an element.
    parts:
      - name: Carbon
        symbol: C
        role: Two carbons per ethylene repeat unit, forming the polymer backbone.
      - name: Hydrogen
        symbol: H
        role: Four hydrogens per repeat unit. JCPE5 says the high hydrogen content slows fast neutrons.
      - name: Boron
        symbol: B
        share: 5 % by weight
        role: Neutron absorber. JCPE5 says the added boron compound absorbs the slowed neutrons.
  risk_groups:
    - title: For people
      lead: Base polyethylene and elemental boron are both described as not classified under GHS in the sheets read. No safety data sheet for the 5 % borated product was read, so its own classification is not verified.
      level: 1
      verdict: Not classified in the sheets read; product sheet not found
      points:
        - label: Base polymer
          line: 'The Borouge polyethylene sheet prints no pictogram, signal word or hazard statement under SS 586: Part 2: 2022.'
        - label: Boron filler
          line: The Materion boron sheet says the substance does not meet GHS criteria, and that dust may irritate the respiratory tract, skin and eyes.
        - label: Dust
          line: Keep machining dust down and ventilated, as the boron sheet advises.
    - title: If it fails
      lead: 'Two failure routes come from the sources: heat under load, and a weaker boron benefit than expected in one preliminary test.'
      points:
        - label: Heat
          line: The heat deflection temperature is 45 °C (JCPE5) or 46.7 °C (MarShield) at 1.8 MPa, well below the melting point of 128 to 135 °C.
        - label: Shielding
          line: A preliminary 190 MeV proton test gave 2.10 µGy per spill for boron-polyethylene at 5.35 g/cm2 against 2.11 µGy per spill for neat HDPE at 5.52 g/cm2.
  why: Borated polyethylene combines a hydrogen-rich polymer with boron, which captures neutrons. JCPE5 is a 5 % boron grade with a density of 1.04 g/cm3 and a melting temperature of 135 °C, both per the manufacturer's page. MarShield's borated polyethylene is printed as 1.01 g/cc with a melting point of 128 °C, so the two datasheets disagree slightly and both values are shown.
  uses:
    - where: Nuclear facilities
      line: MarShield lists vault doors, particle accelerators, hot cells and nuclear storage and transport containers as uses. JCS Nuclear Solutions sells JCPE5 as a neutron shield for nuclear installations.
    - where: Space radiation research
      line: NASA tested boron-polyethylene in a 190 MeV proton beam in 2009. The results were preliminary, and the study says ground data were still to come.
  can_do:
    - label: Shield neutrons
      value: 5 % boron
      line: JCPE5 is loaded with 5 % boron. The page says the hydrogen slows fast neutrons and the boron absorbs the slowed neutrons.
    - label: Stay stiff at room temperature
      value: 1600 MPa
      benchmark: elastic_modulus
      line: JCPE5 prints a tensile modulus of 1600 MPa (ISO 527). MarShield prints 0.7667 GPa (ASTM D638) for its product, so the two sheets are shown side by side.
    - label: Take continuous heat
      value: 80 °C
      benchmark: max_service_temp
      line: JCPE5 gives 80 °C as the continuous allowable service temperature in air for 20,000 hours.
  compare: Borated polyethylene is a polymer shield with a density of 1.04 g/cm3 on one datasheet and 1.01 g/cc on the other. The sources read give no density or dose comparison with a metal or concrete alternative, so no ranking is made. NASA's preliminary Table 1 puts the boron grade close to neat HDPE at similar thickness, and it does not show a clear advantage at 5.35 g/cm2.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Heat deflection temperature
      benchmark: heat_deflection_temperature
    - label: Absorbed dose per spill at about 5 g/cm2
      benchmark: absorbed_dose_per_spill
  handling:
    - Specify the grade and boron content, since the sources print 5 % by weight and the two datasheets differ in property values.
    - Check the current supplier SDS for the grade you buy. No SDS for the 5 % borated product was read.
    - Keep dust down when cutting, since the boron and polyethylene sheets both mention dust hazards.
    - Keep the material below about 45 °C under sustained load.
  good_for:
    - 'Neutron shielding at low to moderate temperature: JCPE5 states it suits low and intermediate neutron flux where elevated temperatures are not expected.'
    - Shielding around vaults, doors and containers in nuclear and medical facilities, as MarShield describes.
    - 'Low-cost shielding: MarShield describes its sheet as a lightweight, cost-effective shielding solution.'
  watch_out:
    - 'Heat under load: deflection starts at 45 °C (JCPE5) and 46.7 °C (MarShield) at 1.8 MPa.'
    - 'Dose benefit: the 2009 NASA preliminary test found no clear advantage over neat HDPE at similar thickness.'
    - 'Solvents and sunlight: MarShield rates continuous sunlight as Limited, and chlorinated solvents, hydrocarbons, ketones and esters as Unacceptable.'
  verdict: Borated polyethylene is a low-cost neutron shield at 5 % boron by weight, with densities of 1.04 and 1.01 printed by the two datasheets and a heat limit near 45 °C under load. The one space test read was preliminary and showed no clear benefit over neat polyethylene at similar thickness, so ground data are the next check.