Polypropylene Sheet, Flame Retardant Electrical Grade

Flame-retardant polypropylene electrical insulation sheet in black, sold by the full sheet.

This is flame-retardant polypropylene electrical insulation sheet - a thin, formable, die-cuttable barrier material for electrical and electronic work, not a structural sheet. It is a filled flame-retardant grade at a specific gravity of 1.035, about 14 percent heavier than plain polypropylene.

The electrical numbers are what you buy it for: dielectric strength 987 V/mil, dielectric breakdown 29,610 V, volume resistivity 3.97 x 10^15 ohm-cm, dielectric constant 1.90 at 1 MHz and dissipation factor 0.0023. Limiting oxygen index is 29 percent, water absorption 0.06 percent, heat deflection 250F at 0.45 MPa (65 psi), and tensile yield 4,000 psi machine direction and 3,200 psi transverse.

It also does something plain polypropylene cannot. Surface energy as produced is at least 50 dynes/cm - well above the roughly 36 mN/m adhesives need - so unlike ordinary polypropylene it prints, laminates and bonds without surface treatment, including foil lamination for EMI and RFI shielding.

It is manufactured to a UL 94 V-0 listing with a 115C relative thermal index and a 600 V comparative tracking index. That listing belongs to the manufacturer and its UL file, not to us - we will supply the documentation for the sheet shipped. Note also that the maker publishes two data pages for this family whose density, dielectric constant and thermal index figures do not agree; the figures above are from the main grade table.

It goes into electrical enclosures and barriers, EV battery insulation, wire organisers, HVAC airflow baffles, UPS and power distribution assemblies, printed-circuit barriers, telecom and LED lighting components, and digital signage.

Outdoor use, and this is the one that comes back as a warranty claim. Standard polypropylene is not UV stabilized. Continuous sunlight is rated limited, and exposure causes progressive loss of tensile strength and elongation - polypropylene's peak photochemical sensitivity sits at 370 nm, inside the UV-A band, which makes it the more vulnerable of the two common polyolefins. For outdoor or UV-exposed service, specify a UV-stabilized polypropylene grade or UV-stabilized HDPE. Color alone is not UV protection, black included: the UV-stabilized polypropylene grades actually sold are blue, beige, gray and white, and no mill we can find publishes a UV service claim for black polypropylene.