Polycarbonate Roll Stock, Clear

General-purpose polycarbonate is the toughest transparent glazing material in common use. The honest version of the impact claim: notched impact strength by ASTM D256 is 12 to 18 ft-lb/in against 0.4 for acrylic, so roughly thirty to forty times acrylic's notched impact, and instrumented impact by ASTM D3763 at 0.125 inch is 47 ft-lb where acrylic and glass are a small fraction of that. We do not quote a multiple against glass, because the only published glass comparison is a maker's bar chart whose values are not printed. Note too that "tougher" is not "stronger": acrylic beats polycarbonate on tensile strength at 10,000 psi against 9,500, on flexural at 17,000 against 13,500, on compressive at 17,000 against 12,500, on surface hardness at Rockwell M95 against M70 and on clarity at 92% transmission against 86%. Polycarbonate wins on impact and on temperature, 240F continuous against 160F.

Published properties: light transmission 86% clear at 0.118 inch, tensile 9,500 psi ultimate and 9,000 at yield on a 340,000 psi modulus with 110% elongation, flexural 13,500 psi on 345,000, compressive 12,500 psi, shear 10,000 psi ultimate, Rockwell M70 and R118, thermal expansion 3.75 x 10^-5 in/in/F, water absorption 0.15%, brittleness temperature minus 200F, specific gravity 1.20.

On flammability, publish the gauge with the rating or do not publish it. Clear general-purpose sheet is UL 94 HB at 0.060 inch and only reaches V-0 around 0.394 inch. For interior finish, the maker publishes Class A at 0.030 inch and Class B at 0.060 inch under IBC Chapter 8, and publishes no class for thicker sheet - so a Class A claim on 1/8 inch stock is unsupported. It also publishes CC-1 under IBC Chapter 26 Section 2606. 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.