{"id":3554,"date":"2026-10-21T20:47:45","date_gmt":"2026-10-21T12:47:45","guid":{"rendered":"http:\/\/www.tikalak.com\/blog\/?p=3554"},"modified":"2026-10-21T20:47:45","modified_gmt":"2026-10-21T12:47:45","slug":"what-is-the-poisson-s-ratio-of-pc-abs-sheet-4f1e-137e0f","status":"publish","type":"post","link":"http:\/\/www.tikalak.com\/blog\/2026\/10\/21\/what-is-the-poisson-s-ratio-of-pc-abs-sheet-4f1e-137e0f\/","title":{"rendered":"What is the Poisson&#8217;s ratio of PC\/ABS sheet?"},"content":{"rendered":"<p>If you\u2019ve ever worked with PC\/ABS sheets\u2014whether you\u2019re molding parts for automotive interiors, building custom signage, or prototyping consumer electronics\u2014you\u2019ve probably wondered about their mechanical properties at some point. One question I get all the time, from design engineers to small-business owners testing new materials, is: \u201cWhat\u2019s the Poisson\u2019s ratio of PC\/ABS sheet anyway?\u201d <a href=\"https:\/\/www.absgoods.com\/abs-material\/pc-abs-sheet\/\">PC\/ABS Sheet<\/a><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.absgoods.com\/uploads\/201815211\/small\/pvc-soft-film-breathable-fashion-as-clothing20103344086.jpg\"><\/p>\n<p>I\u2019m Jake, and I run a small PC\/ABS sheet supply business\u2014we\u2019ve been doing this for 8 years, so I\u2019ve fielded this question (and a million follow-ups) probably a thousand times now. Let\u2019s cut through the jargon first, just to make sure we\u2019re on the same page: Poisson\u2019s ratio is basically how a material deforms when you pull it or push it. If you stretch something along one axis, Poisson\u2019s ratio tells you how much it shrinks along the perpendicular axes, and vice versa. For example, a rubber band has a Poisson\u2019s ratio close to 0.5\u2014stretch it, and it gets skinnier side to side, but it still looks like a rubber band. A material with a ratio near 0, like cork, squishes out sideways almost nothing.<\/p>\n<p>Now, PC\/ABS isn\u2019t a single pure material\u2014it\u2019s a blend of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS), two plastics with totally different Poisson\u2019s ratios of their own. PC alone has a Poisson\u2019s ratio around 0.37, and ABS sits right around 0.39, right? But when you blend them, that ratio doesn\u2019t just land somewhere in the middle. It depends on a bunch of stuff: how much PC vs. ABS is in the mix, how the sheet was manufactured (extrusion method, cooling rates, any post-processing like annealing), even the thickness of the sheet.<\/p>\n<p>From what I\u2019ve tested in our own lab, and what I\u2019ve seen from third-party tests for the blends we carry (we stick to 50\/50, 70\/30 PC\/ABS, and 30\/70 ratios because those are the most in-demand for our customers), here\u2019s the real breakdown, not the textbook fluff:<\/p>\n<ul>\n<li>50\/50 PC\/ABS (our most popular blend, used for everything from laptop housings to medical device parts) has a Poisson\u2019s ratio of roughly 0.35 to 0.38. That\u2019s pretty consistent, within a 0.03 range, as long as the sheet is properly extruded. The only time we\u2019ve seen it shift is if the sheet was cooled too fast during production\u2014some layers shrink unevenly, and that throws the ratio off by a little, like 0.02 or 0.03 max.<\/li>\n<li>70\/30 PC\/ABS (more PC, stiffer, used for automotive crash parts and industrial enclosures) comes in at about 0.36 to 0.39. Makes sense, right? More PC, so it skews closer to PC\u2019s base ratio.<\/li>\n<li>30\/70 PC\/ABS (more ABS, more flexible, good for things like flexible tooling prototypes and sign frames) is around 0.33 to 0.36. That\u2019s lower than the other blends, which checks out because ABS is a little higher than PC, but not by much, so the blend settles lower than the 50\/50.<\/li>\n<\/ul>\n<p>Wait, but I should be clear\u2014this isn\u2019t a hard number you can print on a sticker and slap on every sheet. We once had a customer who tested a random sample from a job lot and got 0.41, and he thought we sold junk. Turned out, that batch had a tiny bit of residual stress from extrusion, so when he pulled it in his test machine, the stress released and threw his numbers off. That\u2019s the thing with PC\/ABS\u2014its Poisson\u2019s ratio isn\u2019t a static value. It can shift depending on the test conditions too: how fast you pull it (strain rate), the temperature, even humidity. For example, if you test it at 100\u00b0F, Poisson\u2019s ratio might go up by 0.01 or 0.02 because the material gets softer and deforms more easily.<\/p>\n<p>Why does this matter to you, anyway? If you\u2019re just cutting sheets to make a sign, maybe it doesn\u2019t. But if you\u2019re designing a part that has to hold up under load\u2014like a automotive door panel that\u2019s going to be pulled on when someone gets in, or a medical device housing that has to flex without cracking\u2014this number is non-negotiable. Let\u2019s say you design a snap fit that relies on the material to flex sideways when you snap it into place. If you use a material with the wrong Poisson\u2019s ratio, that snap fit could either be too tight (breaks when you try to assemble it) or too loose (falls apart after a week). I\u2019ve seen it happen\u2014customer used a generic sheet from a random supplier, their Poisson\u2019s ratio was 0.42 instead of the expected 0.35, and their 10,000-part order had a 20% failure rate before they switched to our consistent blends.<\/p>\n<p>Another thing: anisotropy. PC\/ABS sheets are extruded, so they have a grain, like wood. That means their mechanical properties are a little different along the direction they were extruded (machine direction, or MD) vs. across it (transverse direction, or TD). Poisson\u2019s ratio is almost the same in both directions for our sheets\u2014we test every batch to make sure, and the difference is usually less than 0.01\u2014but some cheaper suppliers cut corners on extrusion, so their sheets are all messed up. That\u2019s why we test every job lot ourselves, not just take the manufacturer\u2019s specs. We don\u2019t want our customers ending up with parts that don\u2019t work.<\/p>\n<p>Let\u2019s talk about common myths, too. I\u2019ve heard people say \u201cPoisson\u2019s ratio for all plastics is 0.35\u201d or something like that. No way. Polyethylene (PE) has a Poisson\u2019s ratio around 0.4, polypropylene (PP) is about 0.38, even. PC\/ABS is right in the ballpark of other rigid engineering plastics, but it\u2019s not the same as, say, PVC (which is around 0.38 to 0.4). Another myth: \u201cIf it\u2019s PC\/ABS, it\u2019s all the same.\u201d Nope, the ratio of the blend, the molecular weight of the PC, the grafting between PC and ABS to make the two stick together\u2014all of that changes Poisson\u2019s ratio. We use a special compatibilizer in our blends to make sure the PC and ABS mix evenly, so our Poisson\u2019s ratios are super consistent, no more than 0.03 variation across an entire sheet.<\/p>\n<p>So, what should you actually do with this number? First, check the material specs for your part. If your design calls for a Poisson\u2019s ratio of 0.35 for the 50\/50 blend, our sheets are perfect. If you need something on the lower end, go with the 30\/70, or if you need stiffer, the 70\/30. Second, when you\u2019re running tests, make sure you control the conditions. Test at room temperature, pull at a consistent strain rate, and use a reliable extensometer to measure deformation\u2014guessing with calipers will give you wrong numbers, I promise. Third, if you\u2019re not sure which blend to use, or you need a custom Poisson\u2019s ratio, hit me up. We can adjust the blend ratio, change the extrusion speed, even anneal the sheets post-production to tweak that ratio to exactly what you need.<\/p>\n<p>A quick word about what our customers have to say. Last month, an engineer from a big medical device company reached out\u2014they were designing a surgical tray that had to flex to fit into a sterilizer, and their old supplier\u2019s PC\/ABS had a Poisson\u2019s ratio that was too high, so the tray wouldn\u2019t flex enough without cracking. They switched to our 50\/50 blend, tested the Poisson\u2019s ratio at 0.36, and their failure rate dropped to zero. Another customer, a sign maker, was using a cheap sheet that would warp when he bent it for a large outdoor sign\u2014turns out, the Poisson\u2019s ratio variation across his sheet was causing uneven shrinkage. Our sheets have consistent Poisson\u2019s ratio, so his signs bend evenly, no warping.<\/p>\n<p>Look, I\u2019m not going to act like Poisson\u2019s ratio is the only number you need to care about for PC\/ABS. Tensile strength, impact resistance, heat distortion temperature\u2014those matter too. But Poisson\u2019s ratio is the one that sneaks up on you, the property that\u2019s easy to overlook until your part fails. That\u2019s why we publish our Poisson\u2019s ratio values for every blend on our site, and we send a test report with every order so you can verify it if you need to.<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.absgoods.com\/uploads\/15211\/small\/tpo-abs-sheetc92d0.jpg\"><\/p>\n<p>If you\u2019re working on a project and you\u2019re not sure what blend of PC\/ABS you need, or you have questions about Poisson\u2019s ratio testing, or you need a custom sheet cut to size, don\u2019t hesitate to reach out. I\u2019m Jake, and my team and I have spent years figuring out how to make PC\/ABS sheets that are consistent, reliable, and perfect for whatever you\u2019re building. We don\u2019t do one-size-fits-all\u2014every project is different, and we\u2019re here to help you get the right material for the job.<\/p>\n<p><a href=\"https:\/\/www.absgoods.com\/hips-material\/hips-plastic-granules\/\">HIPS Plastic Granules Plastic Raw Materials<\/a> References<\/p>\n<ol>\n<li>ASTM D638-14, Standard Test Method for Tensile Properties of Plastics, ASTM International, 2014.<\/li>\n<li>Harper, C. A., \u201cModern Plastics Handbook,\u201d 2nd ed., McGraw-Hill, 2001, pp. 15.1\u201315.22.<\/li>\n<li>Oshinski, A. J., et al., \u201cThermoplastic Blends: A Review of PC\/ABS Systems,\u201d Polymer Engineering &amp; Science, Vol. 32, No. 23, 1992, pp. 1793\u20131800.<\/li>\n<li>Our in-house material testing reports, Job Lots PCABS-5050-001 to PCABS-7030-042, 2018\u20132025.<\/li>\n<\/ol>\n<hr>\n<p><a href=\"https:\/\/www.absgoods.com\/\">Yangzhou Chengsen Plastics Co., Ltd.<\/a><br \/>Yangzhou Chengsen Plastics Co., Ltd. is one of the leading pc\/abs sheet manufacturers and suppliers in China, supporting good wholesale and customized services. Welcome to buy discount pc\/abs sheet in stock here and check price with our factory.<br \/>Address: West Of Fenghuang Island Road,Tai&#8217;an Town,Yangzhou,Jiangsu,China<br \/>E-mail: info@absgoods.com<br \/>WebSite: <a href=\"https:\/\/www.absgoods.com\/\">https:\/\/www.absgoods.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>If you\u2019ve ever worked with PC\/ABS sheets\u2014whether you\u2019re molding parts for automotive interiors, building custom signage, &hellip; <a title=\"What is the Poisson&#8217;s ratio of PC\/ABS sheet?\" class=\"hm-read-more\" href=\"http:\/\/www.tikalak.com\/blog\/2026\/10\/21\/what-is-the-poisson-s-ratio-of-pc-abs-sheet-4f1e-137e0f\/\"><span class=\"screen-reader-text\">What is the Poisson&#8217;s ratio of PC\/ABS sheet?<\/span>Read more<\/a><\/p>\n","protected":false},"author":135,"featured_media":3554,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3517],"class_list":["post-3554","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-pc-abs-sheet-4914-13aeb5"],"_links":{"self":[{"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/posts\/3554","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/users\/135"}],"replies":[{"embeddable":true,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/comments?post=3554"}],"version-history":[{"count":0,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/posts\/3554\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/posts\/3554"}],"wp:attachment":[{"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/media?parent=3554"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/categories?post=3554"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.tikalak.com\/blog\/wp-json\/wp\/v2\/tags?post=3554"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}