Polycarbonate Sheet, Flame Retardant UV Stabilised

This is the UV-stabilised flame-retardant polycarbonate sheet: UL 94 V-0 at 0.080 inch and up, a FAR 25.853 pass from 0.080 to 0.250 inch, light transmission 86% for clear with haze under 1%, and specific gravity 1.20. It is the grade to specify when a panel needs a flame rating AND goes somewhere the sun reaches - exterior enclosures, transit glazing, canopies and signage with a code requirement.

The distinction from the other flame grade matters and is routinely got backwards. Flame-inhibited sheet reaches V-0 at a thinner 0.060 inch and adds 5VA at 0.118, but it is not UV stabilised and its notched Izod is 2 ft-lb/in. This grade needs 0.080 inch for V-0 and does not carry 5VA, but it is UV stabilised and keeps a notched Izod of 15 ft-lb/in - near plain polycarbonate's 12 to 18. So: thinner and higher-rated but interior only, against slightly thicker, tough, and fit for outdoors.

Other properties: tensile 9,500 psi at break, flexural 13,500 psi, compressive 12,500 psi, unnotched Izod no failure at 60, instrumented impact 46 ft-lb, heat deflection 270F at 264 psi and 280F at 66 psi. Temperature, stated honestly. Heat deflection temperature is 270F at 264 psi and 280F at 66 psi by ASTM D648, but that is a short-duration softening test and must not be used as a service limit. Published maximum continuous service temperature in air is 240 to 250F depending on the publisher, with intermittent exposure to 275F published. Parts under sustained load should be derated well below that, and anything load-bearing near the top of the range needs creep data.

One thing to check before you order, and this is distributor practice rather than anything a manufacturer prints. Polycarbonate sheet sold as "1/4 inch" is commonly 0.220 inch, which is the 5.6 mm North American extruded gauge, or 0.236 inch, which is the metric 6 mm gauge - not 0.250 inch. Those are 7% apart in thickness and in weight, and the difference matters wherever the sheet has to fit a frame, a channel or a glazing pocket. The thickness on each listing here is the actual decimal, not the nominal label.

Chemical compatibility and cleaning, which is where most polycarbonate failures start. Clean it with mild diluted dish soap and a soft microfibre cloth, or an ammonia-free glass cleaner. Do NOT use ammoniated glass cleaner - the common blue kind - because ammonia attacks polycarbonate, and the resin maker's own testing shows 0.1% ammonia is enough to do damage in the presence of water. Also avoid abrasive or high-alkaline cleaners, scrapers and squeegees, dry rubbing, and solvent in direct sun. Isopropyl alcohol diluted 50/50 with water handles oil and tar. Acetone, MEK, methylene chloride, chloroform, toluene, xylene and aromatic fuels all attack it, and so do amines and the plasticisers that migrate out of flexible PVC - which is why PVC gasket, tape and cable tie contact is a real failure mode. The important subtlety is that chemical resistance is not a fixed property: stress cracking only develops where the part is in tension, so a cold-bent, over-torqued or tightly framed part will fail with chemicals a compatibility chart calls safe.