A guide to polyvinyl alcohol — what it is, how hydrolysis and viscosity define a grade, and how it's supplied — from a US-based distributor.
Polyvinyl alcohol (PVA) is a water-soluble synthetic polymer made by hydrolyzing polyvinyl acetate. It is used as an adhesive binder, a paper and textile coating, a protective colloid in emulsion polymerization, and a water-soluble film. Stratus Chemical supplies fully and partially hydrolyzed grades, with COA and SDS.
| Chemical name | Polyvinyl alcohol |
|---|---|
| CAS number | 9002-89-5 |
| Molecular formula | (C2H4O)n |
| Molecular weight | Grade-dependent; expressed as solution viscosity, not a fixed value |
| Synonyms | PVA, PVOH, PVAl, poly(vinyl alcohol), poly(ethenol), vinyl alcohol polymer |
| Appearance | White to cream granule or powder |
| Grades supplied | Fully hydrolyzed, partially hydrolyzed |
| Packaging | Bags, supersacks |
Polyvinyl alcohol is one of the few genuinely water-soluble synthetic polymers made at industrial scale. Unlike most polymers it is not made by polymerizing its own monomer — vinyl alcohol is not stable and rearranges to acetaldehyde. PVA is instead produced indirectly: vinyl acetate is polymerized to polyvinyl acetate, and the acetate groups on that backbone are then replaced with hydroxyl groups by alcoholysis in methanol, usually with a sodium hydroxide catalyst.
That production route is the reason the product is defined by two numbers rather than one. Degree of hydrolysis, given in mole percent, says how far the conversion from acetate to hydroxyl was taken. Degree of polymerization, reported commercially as the viscosity of a 4% aqueous solution in centipoise, says how long the chains are. Almost every practical property of a PVA grade — how hot the water has to be to dissolve it, how tacky the solution is, how water-resistant the dried film is — follows from those two figures. When you specify PVA, you are specifying that pair.
The ranges below cover the standard grade families. Individual lots are supplied to a defined grade with a lot-specific COA.
| Fully hydrolyzed | Partially hydrolyzed | |
|---|---|---|
| Viscosity, 4% aqueous (cps) | 3–80 | 3–70 |
| Degree of hydrolysis (mole %) | 95.0–99.8 | 86.0–93.0 |
| Volatiles (wt%) | <5 | <5 |
| Ash (wt%) | <1 | <0.5 |
| pH | 5–7 | 5–7 |
Two notes on reading that table. The 95 mole percent floor on the fully hydrolyzed side comes from a small number of specialty grades; the mainstream fully hydrolyzed grades start at 97 and most sit between 98.5 and 99.2. And the ash ceiling is below 0.7 wt% for nearly all fully hydrolyzed grades — only the lowest-viscosity grades run to 1%.
PVA is a binder and a rheology modifier in water-based adhesives. In wood glues and paper laminating adhesives it is used both on its own and blended with polyvinyl acetate emulsions, where it improves wet tack, open time, and machine handling. Partially hydrolyzed grades are the usual choice because their residual acetate content makes them surface active, so they wet difficult substrates and hold a stable dispersion. Remoistenable gum adhesives on envelopes and tapes are a classic PVA application: the film is hard and non-tacky when dry, then becomes adhesive when wetted.
As a surface size and coating binder, PVA forms a continuous film with high tensile strength and very low porosity. That gives a paper or board sheet grease and oil resistance and a smooth, closed surface for printing. Its low oxygen permeability at moderate humidity also makes it useful as a barrier layer in packaging structures.
Warp yarns are sized before weaving so they survive the mechanical abrasion of the loom. PVA is used for this because it forms a tough, flexible film that adheres well to both cotton and synthetic fibers, and because it washes back off cleanly in hot water at the desizing step — a starch size does not come off as completely. Fully hydrolyzed grades dominate here for their film strength.
In the manufacture of polyvinyl acetate and acrylic emulsions, PVA acts as a protective colloid: it adsorbs onto the growing polymer particles and keeps them from coalescing. The grade chosen controls particle size, emulsion viscosity, and the mechanical and freeze-thaw stability of the finished latex. Partially hydrolyzed grades are standard for this because of their surface activity.
Cast PVA film dissolves completely in water, which is what makes unit-dose detergent pods, agrochemical sachets, and dissolvable laundry bags possible. The degree of hydrolysis is what tunes the dissolution temperature: partially hydrolyzed grades dissolve in cold water, fully hydrolyzed grades need hot water, and formulators choose between them based on whether the package must survive damp handling before use.
This is the first decision in any PVA specification, and it matters more than viscosity.
| Fully hydrolyzed | Partially hydrolyzed | |
|---|---|---|
| Residual acetate | Very low | Roughly 11–14 mole % |
| Water needed to dissolve | Hot, about 90–95 °C | Lower; some grades near cold |
| Surface activity | Low | High — acts as a colloid |
| Adhesion to hydrophobic surfaces | Weaker | Stronger |
| Dried film water resistance | Higher | Lower |
| Solvent and oil resistance | Higher | Lower |
| Typical uses | Textile sizing, barrier coatings, hot-water-soluble film | Adhesives, emulsion polymerization, cold-water film |
The trade-off is real in both directions. Fully hydrolyzed grades have more hydroxyl groups free to hydrogen bond with each other, which builds crystallinity — that is what delivers film strength and resistance, but it is also why they need near-boiling water to dissolve and why they can gel or retrograde in storage as solutions. Partially hydrolyzed grades keep enough acetate to disrupt that crystallinity, so they dissolve easily, stay stable in solution, and wet non-polar substrates far better — at the cost of a softer, more moisture-sensitive dried film. If the finished film has to survive water, go fully hydrolyzed. If the material has to emulsify, disperse, or stick to something greasy, go partially hydrolyzed.
The most common problem with PVA is not storage, it is dissolution. PVA must be added to cold water under agitation and fully dispersed before any heat is applied. If dry powder hits hot water, the outside of each particle gels immediately and seals dry powder inside; the resulting lumps, called fish-eyes, can take hours to break down and often never fully clear. Disperse cold, then raise the temperature with continued stirring and hold until the solution goes clear.
Solutions of fully hydrolyzed grades can gel on standing, particularly at higher concentrations and lower temperatures. Make them at working strength and use them rather than holding them for long periods. In the dry state, PVA is hygroscopic: keep bags closed and off the floor, since absorbed moisture causes caking and shifts the volatiles result on retest.
COA and SDS are provided with every shipment.
Polyvinyl alcohol (PVA) is used as a binder in wood, paper, and packaging adhesives, as a coating and size for paper and textiles, as a protective colloid in emulsion polymerization, and as the film former in water-soluble packaging such as detergent pods. Stratus Chemical supplies fully and partially hydrolyzed grades to US manufacturers.
The CAS number for polyvinyl alcohol is 9002-89-5. Its molecular formula is written (C2H4O)n because it is a polymer, so it has no single fixed molecular weight. Grades are identified instead by degree of hydrolysis in mole percent and by the viscosity of a 4% aqueous solution.
Fully hydrolyzed polyvinyl alcohol has 95 mole percent or more of its acetate groups converted to hydroxyl groups, which gives stronger hydrogen bonding, better solvent and oil resistance, and a more water-resistant dried film. Partially hydrolyzed PVA retains around 11 to 14 mole percent residual acetate, which makes it surface active, easier to dissolve, and better at wetting hydrophobic substrates. Stratus Chemical supplies both types.
Add polyvinyl alcohol to cold water under agitation and disperse it completely before applying any heat, then heat with continued stirring and hold until the solution is clear. Adding PVA powder directly to hot water causes the outer surface of each particle to gel instantly, trapping dry powder inside and forming lumps that are very slow to dissolve. Fully hydrolyzed grades generally need to reach about 90 to 95 °C, while partially hydrolyzed grades dissolve at lower temperatures.
No. Polyvinyl acetate (PVAc, CAS 9003-20-7) is the starting material, and polyvinyl alcohol (PVA, CAS 9002-89-5) is made by hydrolyzing it. PVAc is a water-insoluble emulsion polymer used directly as white glue, while PVA is a water-soluble solid resin. The abbreviations are often confused because both are sometimes written PVA in adhesives literature.
Yes. Polyvinyl alcohol is one of the few water-soluble synthetic polymers produced at industrial scale, and the temperature needed to dissolve it depends on its degree of hydrolysis. Partially hydrolyzed grades at 86 to 89 mole percent dissolve in warm or near-cold water, while fully hydrolyzed grades above 98 mole percent generally require water at about 90 to 95 °C.
Stratus Chemical supplies both fully hydrolyzed and partially hydrolyzed polyvinyl alcohol across a viscosity range of roughly 3 to 80 cps measured as a 4% aqueous solution, in bags and supersacks. Tell us the degree of hydrolysis, viscosity, and volume you need and we will respond with pricing and availability within one business day.
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