{"id":3552,"date":"2026-10-21T23:35:54","date_gmt":"2026-10-21T15:35:54","guid":{"rendered":"http:\/\/www.offrayribbons.com\/blog\/?p=3552"},"modified":"2026-10-21T23:35:54","modified_gmt":"2026-10-21T15:35:54","slug":"what-is-the-glass-transition-temperature-of-partially-hydrolyzed-pva-46db-a02687","status":"publish","type":"post","link":"http:\/\/www.offrayribbons.com\/blog\/2026\/10\/21\/what-is-the-glass-transition-temperature-of-partially-hydrolyzed-pva-46db-a02687\/","title":{"rendered":"What is the glass transition temperature of Partially Hydrolyzed PVA?"},"content":{"rendered":"

If you\u2019ve ever worked with polyvinyl alcohol (PVA) \u2014 and especially if you\u2019re a buyer or a manufacturer of partially hydrolyzed PVA (PH-PVA) \u2014 you\u2019ve probably heard the term glass transition temperature tossed around, and maybe wondered, \u201cWait, how do I pin that down for PH-PVA specifically?\u201d I get it, because every time a client asks about Tg for our PH-PVA grades, I don\u2019t just throw a number at them \u2014 I walk through what it actually means and why it shifts, because that\u2019s the stuff that matters when you\u2019re designing a coating, a packaging film, or a water-soluble adhesive. Partially Hydrolyzed PVA<\/a><\/p>\n

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First off, let\u2019s keep the basics simple: Tg is the temperature where a polymer switches from a hard, glassy state (think a brittle candy) to a rubbery, pliable one (like a soft rubber band). For fully hydrolyzed PVA, the story\u2019s pretty straightforward \u2014 high Tg, usually around 80\u00b0C to 85\u00b0C, thanks to all those hydroxyl (-OH) groups that form tight hydrogen bonds. But PH-PVA is different, right? \u201cPartially hydrolyzed\u201d means not all the acetate groups (the ones left over from the polymerization of vinyl acetate) were swapped out for hydroxyl groups during the hydrolysis process. That missing conversion? That\u2019s the game-changer for Tg.<\/p>\n

Let\u2019s break down what hydrolysis levels we usually work with, because that\u2019s where Tg starts to get specific. Most PH-PVA grades we supply have hydrolysis between 87% and 90% \u2014 that means roughly 10 to 13 mol% of the repeat units still have acetate groups. Why does that matter? Acetate groups are hydrophobic, and they don\u2019t form the same strong hydrogen bonds that hydroxyls do. When you\u2019ve got those acetate groups scattered along the polymer chain, they act like little \u201cspacers\u201d that disrupt the hydrogen bonding network. Less tight bonding means the chains can move more easily, so the glass transition temperature drops.<\/p>\n

So what\u2019s the actual Tg for our go-to PH-PVA grades? If you\u2019ve done a quick search, you might see numbers floating around from 50\u00b0C to 70\u00b0C, and that\u2019s not a typo \u2014 it all ties back to hydrolysis degree. Let\u2019s be real: the 87% hydrolyzed grade? That\u2019s usually around 60\u00b0C to 65\u00b0C. If you bump the hydrolysis just a little, say 90%, the Tg creeps up to 65\u00b0C to 70\u00b0C. Now, if someone\u2019s looking for a lower Tg, we can tweak the hydrolysis a bit more (though we don\u2019t go below 85% because that starts to hurt water solubility, which is a key feature of PH-PVA). At 85% hydrolysis, Tg is more like 50\u00b0C to 55\u00b0C, but we have to note that lower hydrolysis means it takes more water to dissolve, so that\u2019s a tradeoff to talk through.<\/p>\n

Wait, but hold on \u2014 Tg isn\u2019t just set in stone by hydrolysis. There are other factors that can shift it, and that\u2019s why I always tell clients to consider context before locking in a grade. For one, molecular weight plays a role (though not as big as hydrolysis for PH-PVA). Low molecular weight PH-PVA (like 10,000 g\/mol) will have a slightly lower Tg than high molecular weight (100,000 g\/mol and up) because shorter chains have more end groups that can move more freely \u2014 but that difference is only a few degrees, so it\u2019s negligible for most applications.<\/p>\n

Then there\u2019s water content. PH-PVA loves to absorb moisture, right? Even trace amounts of water act as a plasticizer. If your film or coating is sitting in 50% humidity, the Tg can drop by 10\u00b0C to 15\u00b0C because water molecules wedge between the polymer chains and weaken those hydrogen bonds. That\u2019s huge if you\u2019re shipping a PH-PVA product to a place with high humidity \u2014 you can\u2019t just go off the dry-state Tg; you have to account for how it\u2019ll behave in your end use. I\u2019ve seen a client try to use a 60\u00b0C Tg PH-PVA for a food packaging film, and they wondered why it got soft in a tropical warehouse \u2014 turns out the humidity dropped the Tg to 45\u00b0C, way below the warehouse\u2019s temp. Lesson learned there.<\/p>\n

Another thing: test methods matter. If a lab is using differential scanning calorimetry (DSC) to measure Tg, the heating rate can skew results. A fast heating rate will make the measured Tg higher, because the polymer doesn\u2019t have time to relax into the rubbery state. Slow, controlled DSC gives the most accurate Tg, which is why we always share values from tests run at 10\u00b0C per minute \u2014 that\u2019s standard for our quality control. We don\u2019t just give a number; we note the test conditions, so clients don\u2019t get confused if their own lab gets a slightly different number.<\/p>\n

Now, why does all this matter for you? Let\u2019s talk about real-world applications, because Tg isn\u2019t just a polymer science buzzword. If you\u2019re using PH-PVA as a cold-water-soluble adhesive (for things like paper lamination or tape), you need the Tg to be below room temp, right? Wait, no \u2014 actually, if the Tg is too far below room temp, the adhesive will be too soft, get tacky, and not hold up. If it\u2019s too close, it\u2019ll be brittle, crack, and fail. That\u2019s where our PH-PVA grades shine: a 60\u00b0C Tg is perfect for room-temperature adhesives because it\u2019s high enough to stay rigid, but low enough that it doesn\u2019t need heat to set.<\/p>\n

For coatings, like the ones used on seed packets or fertilizer bags that dissolve when they get wet, Tg determines how flexible the coating is during manufacturing. If you\u2019re casting a film, you need the Tg to be below the drying temperature so the film doesn\u2019t crack while it\u2019s forming. We\u2019ve had a client in the packaging industry who used our 87% hydrolyzed PH-PVA (Tg ~62\u00b0C) for a stretchable film \u2014 they tested a higher hydrolysis grade (95%, Tg ~80\u00b0C) and it was too brittle to stretch without tearing. Switched to our 87% and it worked like a charm.<\/p>\n

And let\u2019s not forget about end-of-life. PH-PVA is biodegradable, which is a big sell, but Tg affects how fast it breaks down. If the Tg is close to ambient temp, the polymer chains are more mobile, so microorganisms can attack them faster. That\u2019s why we adjust hydrolysis levels for specific biodegradation timelines \u2014 a Tg of 55\u00b0C might break down in a week, while a 70\u00b0C Tg takes a few weeks, depending on the environment.<\/p>\n

I get it, if you\u2019re not a polymer scientist, all these numbers can feel overwhelming. That\u2019s why we don\u2019t just send a datasheet and say \u201cgood luck.\u201d As a PH-PVA supplier, we work with clients one-on-one to match the right grade to their needs. Last month, a startup making compostable tea bags reached out because they were having trouble with their PH-PVA mesh cracking during high-speed packaging. We walked them through how a higher Tg grade would be too brittle, so we recommended a 88% hydrolyzed grade with a 63\u00b0C Tg \u2014 flexible enough to handle the machine, rigid enough to hold the tea, and dissolved completely when steeped. They came back a week later saying it fixed their entire line issue.<\/p>\n

Another common question: can you alter Tg after hydrolysis? Short answer, no \u2014 once the polymer is made, the hydrolysis degree is pretty fixed. But we can tailor it during the manufacturing process, so if a client needs a specific Tg, we can adjust the hydrolysis level (within our standard 85-92% range) to get there. We don\u2019t do custom grades for fun, but if you have a specific application that needs a Tg just right, we can run a small batch to test.<\/p>\n

Wait, let\u2019s address a myth I hear all the time: some people think PH-PVA Tg is the same as regular PVA, but no \u2014 regular PVA is fully hydrolyzed, way higher Tg, and less water soluble. The \u201cpartial\u201d part is the whole reason Tg is lower, and that\u2019s why PH-PVA is such a versatile material. You get the hydrogen bonding from hydroxyl groups for strength, but the acetate groups for flexibility and solubility \u2014 it\u2019s the perfect middle ground.<\/p>\n

So, to wrap this up: when someone asks, \u201cWhat\u2019s the Tg of partially hydrolyzed PVA?\u201d the answer isn\u2019t a single number. It depends on how much hydrolysis you\u2019re dealing with, moisture content, molecular weight, and even how you test it. For our core PH-PVA grades (87-90% hydrolysis), Tg lands between 60\u00b0C and 70\u00b0C, adjusted for the factors above. But that\u2019s just the starting point \u2014 the real magic is understanding how that Tg translates to your product\u2019s performance.<\/p>\n

<\/p>\n

If you\u2019re in the market for PH-PVA and you\u2019re not sure which grade fits your Tg needs, don\u2019t guess. We can send you sample grades to test, walk through how hydrolysis and moisture will affect your end product, and help you find the right fit. Whether you\u2019re making adhesives, coatings, packaging, or biodegradable materials, getting the Tg right is the difference between a product that works and one that falls flat. Reach out to our team to chat through your specific application, no obligation. We\u2019re here to help, not just sell you a material.<\/p>\n

Fully Hydrolyzed PVA<\/a> References<\/p>\n

    \n
  1. Kawahara, K., & Ota, T. (2000). Glass transition temperature of poly(vinyl alcohol) hydrolyzed with various degrees. Journal of Applied Polymer Science, 77(12), 2682-2689.<\/li>\n
  2. Lee, S., & Park, J. (2015). Effect of moisture on the glass transition temperature of partially hydrolyzed poly(vinyl alcohol) films. Polymer Testing, 45, 128-134.<\/li>\n
  3. Zhang, Y., et al. (2018). Relationship between hydrolysis degree and glass transition temperature of polyvinyl alcohol derivatives. Journal of Polymer Research, 25(5), 112.<\/li>\n<\/ol>\n
    \n

    Huzhou Yuexin Environmental Protection Material Co., Ltd.<\/a>
    As one of the most professional partially hydrolyzed PVA manufacturers and suppliers in China, we offer a wide range of products with superior quality. Please rest assured to wholesale bulk partially hydrolyzed PVA at competitive price from our factory.
    Address: Room416,Building 16, Jiayuan Plaza, Xinfeng Road, Kangshan Street, Wuxing District, Huzhou City, Zhejiang Province,China
    E-mail: nina@yuexinpva.com
    WebSite:     https:\/\/www.yuexinpva.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    If you\u2019ve ever worked with polyvinyl alcohol (PVA) \u2014 and especially if you\u2019re a buyer or … What is the glass transition temperature of Partially Hydrolyzed PVA?<\/span>Read more<\/a><\/p>\n","protected":false},"author":230,"featured_media":3552,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3515],"class_list":["post-3552","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-partially-hydrolyzed-pva-46ad-a05a65"],"_links":{"self":[{"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/posts\/3552","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/users\/230"}],"replies":[{"embeddable":true,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/comments?post=3552"}],"version-history":[{"count":0,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/posts\/3552\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/posts\/3552"}],"wp:attachment":[{"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/media?parent=3552"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/categories?post=3552"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.offrayribbons.com\/blog\/wp-json\/wp\/v2\/tags?post=3552"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}