{"id":7808,"date":"2025-10-13T09:00:00","date_gmt":"2025-10-13T08:00:00","guid":{"rendered":"https:\/\/uplastech.com\/pla-biodegradable-thermoforming\/"},"modified":"2026-10-28T09:22:38","modified_gmt":"2026-10-28T09:22:38","slug":"pla-biodegradable-thermoforming","status":"publish","type":"post","link":"https:\/\/uplastech.com\/pl\/pla-biodegradable-thermoforming\/","title":{"rendered":"PLA Thermoforming: Compostable Trays on Equipment You Already Have"},"content":{"rendered":"<style>\n.upl-blog{font-size:17px;line-height:1.78;color:#1f2937}\n.upl-blog p{margin:0 0 18px}\n.upl-blog h2{font-size:26px;line-height:1.3;color:#0b2b33;margin:46px 0 14px;font-weight:700;letter-spacing:-.015em}\n.upl-blog h3{font-size:19.5px;color:#0d3b47;margin:28px 0 10px;font-weight:700}\n.upl-blog ul,.upl-blog ol{margin:0 0 20px;padding-left:22px}\n.upl-blog li{margin:0 0 9px}\n.upl-blog figure{margin:0 0 34px}\n.upl-blog figure img{width:100%;height:auto;display:block;border-radius:10px}\n.upl-blog figcaption{font-size:13px;color:#6b7280;margin-top:10px;line-height:1.5}\n.upl-blog .toc{background:none;border:0;border-radius:0;padding:0;margin:0 0 34px}\n.upl-blog .toc .lwptoc{margin:0}\n.upl-blog .toc h4{margin:0 0 10px;font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#0d5563}\n.upl-blog .toc ol{margin:0;padding-left:18px;font-size:14.5px}\n.upl-blog .toc li{margin-bottom:6px}\n.upl-blog table{width:100%;border-collapse:collapse;font-size:14.5px;margin:0 0 10px}\n.upl-blog th{background:#0d3b47;color:#fff;text-align:left;padding:11px 13px;font-weight:600;font-size:13.5px;border:0}\n.upl-blog td{padding:11px 13px;border:0;border-bottom:1px solid #e8ebed;vertical-align:top}\n.upl-blog tbody tr:nth-child(even){background:#fafbfc}\n.upl-blog .tablecap{font-size:12.5px;color:#6b7280;margin:0 0 30px}\n.upl-blog .myth{background:#fff8ef;border:1px solid #f6ddbd;border-radius:8px;padding:16px 20px;margin:0 0 26px;font-size:15.5px}\n.upl-blog .myth b{color:#a85c10}\n.upl-blog .callout{background:#f2f8f9;border-radius:8px;padding:18px 22px;margin:0 0 26px;font-size:15.5px;border-left:3px solid #14707f}\n.upl-blog .faq h3{border-top:1px solid #eceff1;padding-top:22px;margin-top:0;font-size:18px}\n.upl-blog .faq h3:first-of-type{border-top:0;padding-top:0}\n.upl-blog .cta{background:linear-gradient(135deg,#0b2b33,#0d5563);color:#fff;border-radius:12px;padding:34px;margin:48px 0 30px}\n.upl-blog .cta h2,.upl-blog .cta .cta-h{color:#fff;margin:0 0 10px;font-size:24px;font-weight:700;line-height:1.3}\n.upl-blog .cta p{color:#c9dee3;margin:0 0 20px;font-size:16px}\n.upl-blog .btn{display:inline-block;background:#e07a1f;color:#fff;text-decoration:none;font-weight:700;padding:13px 26px;border-radius:8px;font-size:15.5px}\n.upl-blog .rel{border-top:1px solid #e8ebed;margin-top:40px;padding-top:26px}\n.upl-blog .rel h4{font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#6b7280;margin:0 0 14px}\n.upl-blog .rel ul{list-style:none;padding:0;margin:0}\n.upl-blog .rel li{padding:11px 0;border-bottom:1px dashed #e8ebed}\n.upl-blog .rel a{text-decoration:none;font-weight:600;font-size:15.5px}\n@media(max-width:640px){.upl-blog h2{font-size:22px}.upl-blog table{font-size:13px}.upl-blog .cta{padding:24px}}\n\/* \u5355\u7bc7\u9875\u9690\u85cf WhatsApp \u95ee\u5019\u5361\uff0c\u53ea\u4fdd\u7559\u5706\u5f62\u6c14\u6ce1\uff0c\u907f\u514d\u906e\u6321\u4fa7\u680f\u8be2\u76d8\u63d0\u4ea4\u6309\u94ae\u3002\n   \u6ce8\u610f\uff1aClick to Chat \u7684\u70b9\u51fb\u903b\u8f91\u662f\u300c\u95ee\u5019\u5361\u5143\u7d20\u5b58\u5728\u5c31\u4e0d\u8df3\u8f6c\u300d\uff0c\u53ea\u9760 CSS \u9690\u85cf\u4f1a\u8ba9\u6c14\u6ce1\u53d8\u6210\u6b7b\u94fe\u63a5\u3002\n   Code Snippets #9\u300cUPL single post: WhatsApp bubble jumps straight to chat\u300d\u8d1f\u8d23\u628a\u8be5\u8282\u70b9\u4ece DOM \u79fb\u9664\uff0c\n   \u4e0b\u9762\u8fd9\u6761 CSS \u53ea\u662f\u79fb\u9664\u524d\u7684\u89c6\u89c9\u515c\u5e95\u3002\u5220 #9 \u524d\u5fc5\u987b\u5148\u5220\u8fd9\u6761\u89c4\u5219\u3002 *\/\nbody.single-post .ht_ctc_chat_greetings_box{display:none !important}\n<\/style>\n<div class=\"upl-blog\">\n<figure>\n<img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/10\/pla-biodegradable-thermoforming.jpg\" alt=\"PLA thermoforming window by thickness and heat deflection temperature against crystallinity\" width=\"1536\" height=\"909\"><figcaption>Amorphous PLA holds its shape to 55 \u00b0C. A hot drink is 85. That gap is the whole engineering problem.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"what\">What PLA is<\/h2>\n<p>Polylactic acid is a polyester made from lactic acid, which is fermented from starch \u2014 usually corn, sometimes sugarcane or cassava. It is the most commercially established bioplastic, and its thermoforming behaviour is close enough to PET that most converters can run it without new equipment.<\/p>\n<p>It is clear, glossy, stiff and printable. It is also brittle, has a low heat deflection temperature in its amorphous form, and its compostability depends entirely on the conditions it meets at end of life.<\/p>\n<p>Those three facts define the market. PLA wins where clarity and a sustainability claim matter and the product is used cold. It loses where the product sees heat, where toughness is required, or where industrial composting is not available.<\/p>\n<table>\n<thead>\n<tr>\n<th>Grade<\/th>\n<th>Characteristic<\/th>\n<th>Forming note<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Amorphous PLA<\/td>\n<td>Clear, standard<\/td>\n<td>Widest window, lowest heat resistance<\/td>\n<\/tr>\n<tr>\n<td>Crystalline PLA (CPLA)<\/td>\n<td>Opaque, heat resistant<\/td>\n<td>Needs hot mould, slower cycle<\/td>\n<\/tr>\n<tr>\n<td>High heat PLA<\/td>\n<td>Stereocomplex<\/td>\n<td>Up to 120 \u00b0C, narrow window<\/td>\n<\/tr>\n<tr>\n<td>PLA blend<\/td>\n<td>With PBAT or starch<\/td>\n<td>Tougher, less clear<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 PLA grades for thermoforming. The choice is decided by the service temperature, not by the forming behaviour.<\/p>\n<h2 id=\"window\">The forming window<\/h2>\n<p>PLA forms between 105 and 145 \u00b0C at the surface. That is lower than PET, which is why a machine set up for APET needs its heaters turned down by 30 to 40 \u00b0C rather than a new oven.<\/p>\n<p>The window is narrow at the bottom end. Below 105 \u00b0C the sheet is stiff and stress-whitens at every radius; the whitening in PLA is more visible than in PET because the material is clear and the craze lines scatter light. Above 145 \u00b0C the sheet sags and becomes tacky enough to stick to the heater or the mould.<\/p>\n<p>PLA also has a thermal history limit. Held above 140 \u00b0C for more than a minute, the molecular weight drops through hydrolysis and the part becomes brittle. The smell of lactic acid in the workshop is the warning sign.<\/p>\n<table>\n<thead>\n<tr>\n<th>Grubo\u015b\u0107<\/th>\n<th>Surface temperature<\/th>\n<th>Czas nagrzewania<\/th>\n<th>Mould temperature<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>0.3 mm<\/td>\n<td>110 \u2013 130 \u00b0C<\/td>\n<td>8 \u2013 14 s<\/td>\n<td>20 \u2013 40 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>0.5 mm<\/td>\n<td>112 \u2013 135 \u00b0C<\/td>\n<td>15 \u2013 25 s<\/td>\n<td>20 \u2013 40 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>0.8 mm<\/td>\n<td>115 \u2013 138 \u00b0C<\/td>\n<td>28 \u2013 45 s<\/td>\n<td>25 \u2013 45 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>1.2 mm<\/td>\n<td>118 \u2013 140 \u00b0C<\/td>\n<td>50 \u2013 80 s<\/td>\n<td>30 \u2013 50 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>2.0 mm<\/td>\n<td>120 \u2013 142 \u00b0C<\/td>\n<td>90 \u2013 140 s<\/td>\n<td>35 \u2013 55 \u00b0C<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 PLA forming parameters for amorphous sheet. For crystalline PLA the mould temperature rises to 90 \u2013 110 \u00b0C and the cycle doubles.<\/p>\n<h2 id=\"heat\">Crystallinity and the heat resistance problem<\/h2>\n<p>Amorphous PLA has a heat deflection temperature of about 55 \u00b0C. A takeaway coffee at 85 \u00b0C, a car interior at 60 \u00b0C in summer, or a microwave will all deform it. This is the single limitation that decides most PLA projects.<\/p>\n<p>The answer is crystallinity. PLA can be crystallised during forming by holding it against a hot mould at 90 to 110 \u00b0C for long enough for the chains to organise. The result is opaque, white, and heat resistant to 120 \u00b0C \u2014 a direct analogue of the APET to CPET transition.<\/p>\n<p>The cost is cycle time. A crystalline PLA tray needs 15 to 30 seconds in the mould against 2 to 4 for an amorphous one, because crystallisation is a time-temperature process and the mould has to stay hot. That is a factor of five to ten on the cycle, and it changes the economics completely.<\/p>\n<div class=\"callout\">If a customer asks for a PLA tray that takes hot food, the answer is crystalline PLA and a hot mould. There is no additive that makes amorphous PLA heat resistant.<\/div>\n<h2 id=\"drying\">Drying: less critical than PET, still necessary<\/h2>\n<p>PLA absorbs about 0.2 percent moisture, less than PET and more than PS. At forming temperature, moisture causes hydrolysis and a loss of molecular weight, which shows as brittleness rather than as bubbles.<\/p>\n<p>The target is 0.025 percent or below. At 60 \u00b0C in a desiccant dryer that takes four hours; at 80 \u00b0C it takes two but risks the pellets sticking together in the hopper. Most sheet suppliers dry before winding and ship in a sealed bag, in which case the converter only needs to keep the sheet dry.<\/p>\n<p>Sheet stored in an open warehouse will pick up moisture within days. A roll that has been open for a week should be re-dried before use, and the drying must be at low temperature to avoid the pellets or the sheet sticking.<\/p>\n<h2 id=\"compost\">Compostability: what the claim actually requires<\/h2>\n<p>PLA is certified industrially compostable to EN 13432 or ASTM D6400. Both standards require disintegration within 12 weeks and biodegradation of 90 percent within 180 days under controlled conditions of 58 \u00b0C and high humidity.<\/p>\n<p>Those conditions exist in an industrial composting facility. They do not exist in a home compost heap, in a landfill, or in the sea. A PLA cup in a home compost bin will still be recognisable after a year. A PLA cup in the ocean behaves like any other plastic.<\/p>\n<p>This matters commercially because the claim is regulated. In the EU, describing a PLA pack as biodegradable without qualifying it as industrially compostable is a misleading claim. In several markets the pack must also be a colour that sorting equipment recognises \u2014 usually green \u2014 and must carry the certification mark.<\/p>\n<p>The practical requirement is that the collection infrastructure exists. A compostable pack in a market with no industrial composting is functionally the same as a conventional plastic pack, with a better story and a worse carbon footprint.<\/p>\n<h2 id=\"running\">Running PLA on PET equipment<\/h2>\n<p>The changeover is mostly temperature. Heaters down 30 to 40 \u00b0C, mould temperature down to 20 to 40 \u00b0C, and the vacuum and pressure settings can stay as they were because PLA's forming behaviour is similar to APET.<\/p>\n<p>The differences that catch people are trimming and static. PLA is more brittle than PET, so a steel rule die that cuts PET cleanly will crack a PLA part. A matched punch or a heated blade gives a better edge. PLA also generates more static than PET, which makes parts stick together and attracts dust.<\/p>\n<p>Extrusion coating and sealing are different too. PLA seals at 90 to 120 \u00b0C against a PLA-coated card, lower than PVC or PET, and the seal is more sensitive to pressure. A sealing machine set for PVC will burn through a PLA blister.<\/p>\n<div class=\"faq\">\n<h3>At what temperature does PLA thermoform?<\/h3>\n<p>105 to 145 \u00b0C at the surface, lower than PET. A machine set up for APET needs its heaters turned down 30 to 40 \u00b0C.<\/p>\n<h3>Why does my PLA tray deform with hot food?<\/h3>\n<p>Amorphous PLA has a heat deflection temperature of about 55 \u00b0C. For hot fill or microwave use you need crystalline PLA formed against a hot mould at 90 to 110 \u00b0C.<\/p>\n<h3>Is PLA home compostable?<\/h3>\n<p>No. PLA is certified industrially compostable to EN 13432, which requires 58 \u00b0C and controlled humidity. In a home compost heap it will not break down in a useful time.<\/p>\n<h3>Does PLA need drying before thermoforming?<\/h3>\n<p>Yes, to about 0.025 percent. Four hours at 60 \u00b0C. Moisture causes hydrolysis and makes the part brittle rather than producing visible bubbles.<\/p>\n<h3>Can PLA be run on the same line as PET?<\/h3>\n<p>Yes, with the heaters turned down and the mould temperature reduced. Trimming needs attention because PLA is more brittle, and static is higher.<\/p>\n<h3>What is the difference between PLA and CPLA?<\/h3>\n<p>CPLA is crystallised PLA, formed against a hot mould so that it becomes opaque and heat resistant to about 120 \u00b0C. The cycle time is five to ten times longer.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">Developing a compostable pack?<\/p>\n<p>Tell us the product, the fill temperature and the market. We will tell you whether amorphous or crystalline PLA is right, and what the cycle really costs.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/pl\/custom-vacuum-forming\/\">Talk to a thermoforming engineer<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/pl\/pet-rpet-thermoforming\/\">PET and rPET Thermoforming<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/pl\/cpet-ovenable-trays\/\">CPET Ovenable Trays<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/pl\/why-thermoformed-packaging-is-better-for-the-environment\/\">Why Thermoformed Packaging Is Better for the Environment<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/pl\/food-contact-thermoforming-compliance\/\">Food Contact Compliance for Thermoformed Packaging<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/pl\/pp-cup-thermoforming\/\">PP Cup Thermoforming<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>PLA forms at 105 to 145 \u00b0C, which means it runs on a machine set up for PET with the heaters turned down. The complication is that amorphous PLA softens at 55 \u00b0C, and a coffee cup is hotter than that.<\/p>","protected":false},"author":1,"featured_media":7807,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"PLA Thermoforming: Forming Window, Crystallinity and Heat Re","_seopress_titles_desc":"PLA thermoforming guide: 105-145 C window, drying, crystallinity and heat deflection, compostability claims, running PLA on PET equipment and the defects each c","_seopress_robots_index":"","_seopress_robots_follow":"","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"29","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"","footnotes":""},"categories":[29],"tags":[],"class_list":["post-7808","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vacuum-forming"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/posts\/7808","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/comments?post=7808"}],"version-history":[{"count":1,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/posts\/7808\/revisions"}],"predecessor-version":[{"id":7868,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/posts\/7808\/revisions\/7868"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/media\/7807"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/media?parent=7808"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/categories?post=7808"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/pl\/wp-json\/wp\/v2\/tags?post=7808"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}