| HS Code | 645945 |
| Chemical Name | Poly(vinyl alcohol), aqueous solution |
| Cas Number | 9002-89-5 |
| Appearance | Clear to slightly hazy, viscous aqueous liquid |
| Odour | Mild characteristic polyvinyl alcohol odour |
| Solids Content | 24.0 ± 1.0 wt% |
| Viscosity At 25c | 203 cP (mPa·s) |
| Ph | 5.0 - 7.0 |
| Specific Gravity | 1.05 |
| Boiling Point | 100 °C (212 °F) |
| Freezing Point | Around 0 °C (32 °F) |
| Solubility | Completely miscible with water |
| Degree Of Hydrolysis | 99.0 - 99.8 mol% (fully hydrolyzed) |
As an accredited SELVOL Polyvinyl Alcohol 24-203 Solution factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SELVOL Polyvinyl Alcohol 24-203 Solution is packaged in 200 kg drums and 1,000 kg IBC totes, sealed and labeled. |
| Container Loading (20′ FCL) | Load 20' FCL with drums/IBCs of SELVOL Polyvinyl Alcohol 24-203 Solution; secure pallets, prevent leakage, label, and ventilate. |
| Shipping | SELVOL Polyvinyl Alcohol 24-203 Solution is not classified as dangerous goods under DOT, IMDG, or IATA regulations. Ship in leakproof, properly labeled containers such as drums or totes, protected from freezing and contamination. Follow standard chemical handling procedures and refer to the SDS for emergency response and spill details. |
| Storage | Store SELVOL Polyvinyl Alcohol 24-203 Solution in its original, tightly closed container in a cool, dry, well-ventilated area away from direct sunlight and heat. Protect from freezing and extreme temperatures. Keep separated from oxidizing agents and incompatible materials. Ensure proper labeling and containment to prevent spills, maintaining good housekeeping practices throughout storage. |
| Shelf Life | Shelf life is six months when stored in original tightly sealed containers at room temperature, protected from freezing and contamination. |
For indirect food-contact paper packaging seams, the adhesive falls under 21 CFR 175.105; the PVOH component is evaluated under 21 CFR 176.170 when the final article is intended for aqueous or fatty food contact. EU import requires registration under REACH Regulation (EC) No 1907/2006, and residual vinyl acetate monomer must be declared against the limit specified in the current Annex XVII entries where applicable. Fibre-tear values are assessed after conditioning according to TAPPI T 402; comparative numerical adhesion data are generated with the block shear method of ASTM D4501. Machine-side microbial stability must be monitored by viscosity decay: a loss greater than 15% over 8 h in the diluted letdown indicates biopolymer degradation and requires replacement or addition of a preservative system compatible with 21 CFR 175.105. High-calcium paper dust and alkaline fillers above pH 7.5 reduce storage stability by forming insoluble calcium-PVOH complexes at the doctor blade; the installation should therefore include a 100 μm inline filter before the applicator.
Terminal paper-converting products that rely on this adhesive profile include spiral-wound paper tubes with inner diameter tolerances below ±0.5 mm, multiwall sack bottom pasting, corrugated case conversion under high-speed folding, paperboard edge lamination, and envelope seam gumming. The adhesive is not recommended for wet-lap laminations where water resistance above 24 h soak is mandatory without crosslinker addition; in such cases, the 24-203 Solution must be co-formulated with a glyoxal or carbonate-zirconate crosslinker at 0.05–0.2 parts per 100 parts dry starch and retested for pot life, because the PVOH crosslinking reaction consumes free hydroxyl groups and raises the storage modulus to a level that can pull fibre from uncoated recycled linerboard.
To prevent fibre-to-metal slippage in air-jet loom preparation, the 24-203 Solution is diluted to 7–10% dry solids and applied in a two-size-box slasher at 12–25 m/min. The size box temperature is held at 70–75 °C; lower temperatures reduce wetting of hydrophobic filament bundles, while temperatures above 80 °C accelerate hydrolysis of residual spin finish and produce sloughing at the warp beam. Add-on is set by squeeze roll pressure between 20 and 40 N/cm, giving a dry PVOH add-on of 1.0–1.5% on yarn mass for low-denier polyester and 2.5–3.0% for regenerated cellulose-rich warps where greater film stiffness is required. The dried size film exhibits a glass transition near 70–78 °C; loom-room relative humidity above 65% plasticises the PVOH film, reducing its tensile modulus and increasing shedding at the reed, particularly on sateen constructions.
Production-scale observations on a seven-cylinder drying section indicate that cylinder surface temperatures above 135 °C form a skin on the film and cause flake-off, while temperatures below 110 °C leave residual moisture above 3.5% and cause blocking between adjacent winds on the loom beam. Sized warp tensile strength retention is measured according to ISO 2062:2009; abrasion resistance is evaluated by ASTM D3885; and yarn hairiness is monitored on a Uster Tester 5 hairiness module. On a 190 cm air-jet machine inserting at 700 picks/min, the warp must retain at least 99.75% strength per 100,000 reed contact cycles to avoid end breaks; this threshold is used as an internal acceptance criterion when changing size formulations. For formaldehyde-free low-temperature desizing, the PVOH film is removed with 1–2 g/L oxidative desizing agent at 60 °C, avoiding alkaline hydrolysis of the polyester substrate.
Compliance for textile auxiliaries is assessed under REACH Regulation (EC) No 1907/2006; if the fabric enters apparel or home textile markets, the size formulation must pass the relevant restricted substance lists under the purchasing contract, including azo-disperse and heavy-metal constraints. The as-received solution is not a finished size and must be formulated with lubricants or antistats only if the subsequent weaving operation demonstrates static charge accumulation above 5 kV on running yarn. Terminal products include woven polyester linings, high-density filament shirting, embroidery stabiliser base fabrics, and compressed-air filter fabrics. Published data for the 24-203 Solution on polypropylene tape yarn is limited; a pilot trial with a minimum of 1,500 m warp and 6 h continuous weaving is recommended before specifying add-on in that configuration.
In a 20,000 L stainless-steel pressure reactor for vinyl acetate-ethylene dispersion polymerisation, the vessel is charged with demineralised water, buffer salts, and Selvol Polyvinyl Alcohol 24-203 Solution at 4–8 parts dry PVOH per 100 parts total monomer. Because the product is a liquid, the separate pre-dissolution step for granular PVOH at 85–90 °C for 60–90 min is eliminated, reducing batch preparation by approximately 75–90 min and removing one hot-water jacket cycle. The reactor is equipped with two 45° pitched-blade turbines and four baffles; initial aqueous phase viscosity at 60 °C is from 15 to 30 mPa·s and rises to 300–700 mPa·s during monomer addition as the continuous phase thickens. This viscosity rise controls pre-nucleation and shifts the volume mean particle size toward 0.8–1.5 μm. Grafting extent between PVOH and vinyl acetate is monitored by iodine colour complex formation; over-grafting increases long-chain branching and produces high shear-stable dispersions but may reduce low-shear viscoelasticity.
The protective colloid function is sensitive to redox initiator chemistry and pH. With sodium persulfate at 0.1–0.3 parts per 100 monomer, chain transfer at the 1,2-diol and terminal carboxylic acid sites of PVOH creates in-situ graft copolymers that lower stripping-vacuum foam and improve wettability; excessive chain transfer, however, reduces the hydrodynamic volume and lowers final dispersion viscosity. The pH is controlled with a sodium bicarbonate or formate buffer at 4.0–4.8. Excursions above pH 5.5 during ethylene stripping cause hydrolysis of residual vinyl acetate sequences on the PVOH backbone, altering the cloud point and reducing colloidal shielding against coagulum. Post-polymerisation stripping uses steam at 70–80 °C under 0.3–0.5 bar vacuum to reduce residual monomer content; stripping temperatures above 90 °C degrade PVOH and increase sediment mass retained on a 100 μm screen.
The final dispersion is tested at 25 °C for viscosity by ISO 2555, pH by ISO 976, particle size by ISO 22412:2017, dry solids by ISO 3251, and residual vinyl acetate monomer by ISO 13741-1:1998. Food-contact dispersions fall under 21 CFR 176.170(c) and 21 CFR 176.180 for paper and paperboard coatings; the corresponding EU declarations are made under Regulation (EU) No 10/2011 and EC 1907/2006. Terminal emulsion products include vinyl acetate-ethylene interior architectural coatings, paper-coating binders, wood-adhesive intermediates, and nonwoven binders for wipe substrates. The solution form is not suitable as the sole protective colloid in styrene-acrylic systems without compatibility testing because styrene has a much lower reactivity with PVOH radicals, and the resulting dispersion may show macroscopic serum separation above 50 °C.
| Property | Standard or clause |
|---|---|
| Apparent viscosity | ISO 2555 |
| pH | ISO 976 |
| Particle size distribution | ISO 22412:2017 |
| Non-volatile content | ISO 3251 |
| Residual vinyl acetate monomer | ISO 13741-1:1998 |
| Food-contact paper coating | 21 CFR 176.170(c) |
| Food-contact paperboard | 21 CFR 176.180 |
| EU plastic food-contact compliance | Regulation (EU) No 10/2011 |
When fine paper grades run through a puddle or metering size press at 800–1,200 m/min, Selvol Polyvinyl Alcohol 24-203 Solution is blended with oxidised starch or low-viscosity ethylated starch at 2–5 parts dry PVOH per 100 parts starch solids. The PVOH reduces ribbing in the transfer film and improves the smoothness of the metering gate, but the final dry PVOH add-on is kept below 0.6 g/m² to avoid blocking in the reel and sheeting. At higher add-on, the static coefficient of friction of the sized sheet against steel can rise above 0.35, producing reel-side marks and double-sheet feeding faults in high-speed sheeters. The size press solution temperature is maintained at 50–60 °C because lower temperatures raise Brookfield viscosity and cause gate pressure swings.
Printability and water-absorption tests use ISO 535 for Cobb value, ISO 3783 for surface strength, and TAPPI T 441 for water absorptiveness of sized paper. Food-contact grades comply with 21 CFR 176.170 and 21 CFR 176.180; EU compliance for paper and board is assessed under Regulation (EU) No 10/2011 and the relevant BfR recommendations for paper used in food contact. The solution itself must pass through a 100 μm basket filter before the size press supply tank to remove dried skin that forms at the day-tank headspace. If the starch mixture pH rises above 7.5, borax or glyoxal crosslinkers must not be added simultaneously with the PVOH because the PVOH-boron complex creates gel particles larger than 150 μm that are visible as print mottle. Incompatibilities also include highly cationic wet-strength resins, which can precipitate the PVOH and reduce the charge balance of the wet sheet.
Typical terminal products include woodfree offset printing paper, copy paper, linerboard with improved surface strength, envelope base stock, and inkjet paper treated at the size press. This application is considered a shallow-formulation zone because the PVOH content is low and the main performance variable is the starch ratio; extensive reformulation is not required unless the mill changes from acid to alkaline papermaking or introduces significant ash levels above 20% in the base sheet. In that case, the retention of the PVOH at the size press is reduced by the higher pore volume, and the addition ratio must be shifted to the top of the stated range, with Cobb-value monitoring used for confirmation.
For unit-dose detergent pouch film, the slot-die casting stage receives Selvol Polyvinyl Alcohol 24-203 Solution after degassing under 50–100 mbar for at least 20 min to remove entrained air. Glycerin or sorbitol plasticizer is metered into the solution at 10–25 parts per 100 parts dry PVOH, with the lower half of the range used for detergent pod film requiring high cold-water solubility and the upper half for agrochemical sachets requiring lower dusting. The solution is cast onto a stainless-steel belt or PET release liner through a slot die with a wet gap of 0.4–0.8 mm; after drying, the film thickness is typically 40–80 μm. The four-zone drying oven uses zone setpoints of 70 °C, 80 °C, 85 °C, and 70 °C to allow water evaporation before a surface skin closes the film. A production line running at 8–15 m/min exhibits bubble defects when dissolved oxygen exceeds 4 mg/L or when the solution temperature at the die falls below 22 °C. The cast film is conditioned at 20–25 °C and 35–50% relative humidity before slitting; lower humidity produces edge fracture, while higher humidity causes blocking on the unwind.
Seal strength after jaw release at 120–140 °C for 0.5–1.0 s is measured by ASTM F88/F88M. Tensile properties of the film are determined according to ASTM D882 and ISO 527-3; in-process moisture is quantified by Karl Fischer titration or ISO 15512, with typical target moisture of 8–12% depending on pouch geometry. Dissolution rate at 20 °C in deionised water is not a fixed property; it is governed by residual PVOH crystallinity, which is reduced by holding the solution at 80 °C for 30 min before casting. On an automatic pouch machine at 120 pouches/min, the film tends to stick to heated tooling below 0.5 MPa clamp pressure; release coatings on the seal bars are necessary. Published data for the 24-203 Solution as a sole film former in that precise sealing configuration is limited, so plant trials with a reference polyester-reinforced PVOH film are recommended.
Regulatory and performance testing includes OECD 301B for ready biodegradability of the film ingredients, the EU Detergents Regulation EC No 648/2004 for detergent packaging compatibility labelling, and 21 CFR 177.1670 for PVOH used in food-contact films within extractives limits. Terminal products include laundry detergent unit-dose pouches, dishwasher detergent pods, agrochemical water-soluble sachets, dye and cement additive dosing packs. The PVOH film is incompatible with cationic detergents above 5% actives in the filled formulation because cationic surfactants can precipitate the PVOH and embrittle the sealed seam; this limitation must be resolved by reformulating the liquid payload or by using a barrier liner.
| Test parameter | Method or standard |
|---|---|
| Thickness profile | ISO 4593 |
| Tensile strength and elongation | ASTM D882, ISO 527-3 |
| Heat-seal strength | ASTM F88/F88M |
| Water content | ISO 15512 |
| Ready biodegradability | OECD 301B |
| PVOH food-contact film compliance | 21 CFR 177.1670 |
Alumina tape casting slurries based on 24-203 Solution require the PVOH binder to be combined with deionised water, a plasticizer, and a dispersant to produce a slurry at 45–55 wt% ceramic solids. The PVOH binder is added at 3–7 parts dry PVOH per 100 parts ceramic powder; this ratio is low enough to prevent green-tape embrittlement but high enough to provide tensile strength for handling. The slurry is de-aired under vacuum and cast with a doctor blade gap of 0.8–1.2 mm onto a polyethylene terephthalate carrier. Shear viscosity is controlled at 20–30 Pa·s at 10 s⁻¹ using a cone-and-plate viscometer, while the high-shear viscosity at 500 s⁻¹ is kept below 1 Pa·s to ensure levelling without blade buildup.
The critical process conflict is binder burnout, not casting. A ramp rate of 5 °C/min to 450–500 °C followed by a 30 min soak oxidises the PVOH without leaving carbon residue above 0.05% on the fired ceramic. Shortening the soak produces black-core defects in alumina substrates because decomposition gases cannot escape through the closing pore network; lengthening the soak above 60 min increases grain growth at the surface and reduces fired flexural strength. Fired density and water absorption are tested by ASTM C373-18; binder content is validated by thermogravimetric analysis at 10 °C/min in air from 100 °C to 650 °C. Clean-room tape casting benefits from the low cation content of the solution, but the lot certificate must confirm sodium and potassium levels below 100 ppm because alkali contamination modifies the sintering temperature.
Compliance for electronic ceramic substrates is determined by the end application; raw material quality is usually screened under ISO 14604 for advanced technical ceramics where referenced, while the PVOH binder's burn-off is assessed by gravimetric residue and not by RoHS directly. Terminal products include multilayer ceramic substrates, high-purity alumina sheets for power electronics, ceramic fuel-cell green tapes, and wear-resistant alumina tiles. The solution is not suitable for highly reactive aluminium nitride slurries unless the water content in the solvent mixture is strictly controlled, because hydrolysis of the ceramic powder consumes water and shifts the slurry viscosity into an uncastable range within 4–6 h.
Competitive SELVOL Polyvinyl Alcohol 24-203 Solution prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615380400285 or mail to sales2@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615380400285
Email: sales2@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
SELVOL Polyvinyl Alcohol 24-203 Solution is an aqueous delivery form of the partially hydrolyzed polyvinyl alcohol grade SELVOL 24-203, CAS 9002-89-5. The underlying dry-grade polymer is controlled within a 4.0–5.0 mPa·s viscosity window for a 4% aqueous solution at 20 °C, measured by falling-ball technique under ISO 12058, and a degree of hydrolysis of 87.0–89.0 mol%, determined by saponification-based chemistry in accordance with JIS K6726. The pH of the solution is normally 4.5–6.5 when measured by ISO 976, and ash content is specified at ≤0.5% by ISO 3451-1. Because the material is supplied as a solution, the active polymer concentration is not a universal constant; it is set by supply specification, commonly 10–25 wt%, and must be confirmed by non-volatile residue gravimetry under ISO 3251 before the solution is metered into viscosity-sensitive processes.
The 87.0–89.0 mol% hydrolysis range leaves 11–13 mol% residual acetate groups along the polymer backbone. Those acetate groups disrupt interchain hydrogen bonding enough to permit cold-water dissolution at 20–25 °C, whereas fully hydrolyzed grades in the 98–99 mol% range generally require heating above 80 °C and extended hold time for complete hydration. The acetate content also alters the interfacial tension and steric stabilization behavior of the polymer; partially hydrolyzed PVOH is a more effective protective colloid in many emulsion systems than a fully hydrolyzed material of equivalent viscosity. The trade-off appears in dried-film performance: residual acetate reduces tensile strength and hot-water resistance relative to a fully hydrolyzed grade. The 24-203 solution therefore functions between low-viscosity surfactant-like stabilizers and high-molecular-weight fully hydrolyzed film formers.
| Parameter | Control range or limit | Test method |
|---|---|---|
| Active solution concentration | 10–25 wt%, as negotiated; verify per lot | ISO 3251 |
| Viscosity, 4% solution, 20 °C | 4.0–5.0 mPa·s | ISO 12058 |
| Degree of hydrolysis | 87.0–89.0 mol% | JIS K6726 |
| pH | 4.5–6.5 | ISO 976 |
| Ash content, dry basis | ≤0.5% | ISO 3451-1 |
| Volatile matter, dry basis | ≤5.0% | ISO 3251 by difference |
The principal processing difference is the temperature required for full solubility. A 4% stirred batch of 24-203 solution can be prepared without heat when the water is deionized and temperature is maintained at 20–25 °C; this is not the case for fully hydrolyzed PVOH grades with equivalent viscosity, which generally require slurry heating to 80–95 °C and a minimum hold time. The viscosity response is also different after complete dissolution: 24-203 builds viscosity in a more linear relationship with concentration at low solids, while fully hydrolyzed grades can form stronger hydrogen-bonded networks and develop higher gel strength as temperature drops. In hot coating lines, the partially hydrolyzed grade retains lower hot-water resistance, which can be either a limitation in water-resistant barrier coatings or an advantage in repulpable paper grades.
The temperature coefficient of the solution’s viscosity is negative and non-linear. When the solution is cooled toward 5 °C, low-shear viscosity rises as intermolecular hydrogen bonding increases; when it is heated to 60–70 °C, viscosity drops and the solution again approaches Newtonian behavior. This has direct consequences for sizing and coating lines because a cold morning start-up may require higher pump pressure or reduced line speed even when solids content is unchanged. Inline temperature-compensated viscosity measurement is therefore preferable to simple dip-tube or efflux cup methods for process control.
When borate crosslinkers are introduced into an adhesive or coating formulation, the 1,3-diol residues in the polyvinyl alcohol chain react with borate ions to form a reversible monodiol/di-diol complex. Viscosity increases rapidly with pH and borate concentration; production lines using 24-203 solution with boric acid or borax therefore require pH-stat control and inline viscosity monitoring because the product’s pH window of 4.5–6.5 shifts upward during borax addition and can pass through an irreversible precipitation boundary if the dose is uncontrolled. This sensitivity differs from plasticizer-thickened starch adhesives, which do not show the same borate-diol complexation response.
Paper-coating and water-remoistenable adhesive operations use the product as a film-forming binder where cold dissolution and remoistenability are more important than permanent water resistance. In these converting lines, the solution is metered into a pigment coating color at low PVOH addition levels, typically below 2 parts per hundred parts pigment, and dried surface strength is assessed by IGT pick-resistance testing under ISO 3783. The remoistening step later reintroduces water through a lick roll or spray bar; partial hydrolysis lowers the rewet temperature needed to develop tack. However, dried films remain water-soluble unless a crosslinker is added. The operational limit is therefore clear: permanent water resistance must be designed through crosslinking or overcoating, not expected from the base polymer.
In vinyl acetate, vinyl acetate-ethylene, and acrylic emulsion processes, the solution is introduced as the protective-colloid phase to control particle size, shelf stability, and end-use rheology. The product’s partial hydrolysis and 4.0–5.0 mPa·s viscosity at 4% solids mean that it can be pre-diluted and fed without hot dissolution. The feed configuration should avoid localized high-concentration zones at the monomer addition nozzle; direct feed into a stirred monomer-rich region can create transient viscous skins that later hydrate incompletely. Jacketed stainless steel reactors with pitched-blade agitation are typical; the PVOH phase is usually charged as an initial reactor heel or as an aqueous feed stream, depending on whether the target particle-size distribution is monomodal or bimodal.
The continuous phase viscosity in the final emulsion is governed by PVOH concentration, molecular weight, and the degree of graft formation during polymerization. At higher PVOH solids in the aqueous phase, low-shear Brookfield viscosity rises and shear-thinning becomes more pronounced; inline process viscometers must be calibrated against the specific formulation because the 24-203 solution itself is Newtonian at 4% but the compounded emulsion is not. In published vinyl acetate-acrylic systems, medium-viscosity partially hydrolyzed PVOH levels are commonly observed in the 2–6 phm range, but this window is not a universal specification; particle-size distribution, coagulum, and dry-film water sensitivity must be rebalanced for each monomer set. Published monomer-specific formulation data for 24-203 is limited to supplier technical service trials and production records; therefore, reactor trials are required when replacing a fully hydrolyzed grade or a low-viscosity partially hydrolyzed grade.
The solution’s pH 4.5–6.5 range is close to the optimum decomposition window for persulfate initiators at typical reaction temperatures of 70–85 °C. If the pH is shifted upward by ammonia or sodium bicarbonate buffers, the hydrolysis rate of vinyl acetate increases, and the graft level between PVOH and vinyl acetate can change. The resulting changes in particle-size distribution and latex viscosity are usually larger than those introduced by small variations in the PVOH feed rate. This is a critical threshold conflict in continuous or semi-batch processes where pH control and temperature control interact.
On slasher sizing lines for spun cotton and polyester-cotton yarns, the solution is blended with starch or acrylic size binders at size-box temperatures of 65–85 °C. Typical size-box solids are maintained by refractometric control; PVOH contributes film adhesion to the yarn surface and reduces hairiness without requiring a separate wax or lubricant. Yarn tensile retention is measured by ASTM D2256, and abrasion resistance is evaluated by ASTM D3885 or equivalent loom-stop records. The partial hydrolysis level is an advantage in desizing because the size film can be removed by hot-water washing; however, complete removal requires sufficient water temperature and mechanical action, and residual PVOH on the fabric can interfere with later optical brightener pickup if desizing is incomplete. Desizing of woven fabrics containing 24-203-based size is performed with hot-water washes above 70 °C; cold water below 40 °C rewets the size film but does not fully dissolve it. In reuse systems, the dissolved PVOH can accumulate in the desize bath and alter liquor viscosity, requiring overflow dilution or membrane filtration.
The polyvinyl alcohol ingredient under CAS 9002-89-5 may be referenced in food-contact regulations where PVOH is cleared as an indirect additive, including 21 CFR 175.105, 21 CFR 176.170, and 21 CFR 176.180, but end-use compliance is formulation-specific and depends on the finished article, extractives limits, and use conditions. The solution form does not automatically confer food-contact clearance; converters must obtain the appropriate regulatory declaration from the supplier for the specific lot and application.
Storage of aqueous PVOH solution requires a closed, agitated or recirculated tank at 5–35 °C. Prolonged holding at ambient temperature without biocide protection permits microbial growth, which can reduce viscosity and produce organic acid by-products. Repeated freeze-thaw cycles are outside the product’s operational boundary; freezing can cause local polymer enrichment or phase separation that is not fully reversible by simple remixing. The solution should be pre-filtered through a 100–250 µm bag or cartridge filter before use in coating or spraying operations to remove any skin or gel particles formed during storage. Long-term viscosity drift in aqueous PVOH solutions is normally slow when the solution is stored under nitrogen or another inert gas and protected from light. However, polyvinyl alcohol solutions are sensitive to metal-ion contamination, especially iron and copper, which can catalyze oxidative degradation. Storage tanks and piping for the solution should be constructed of 316L stainless steel or compatible plastics; carbon steel should be avoided unless fully lined because corrosion products accelerate viscosity loss.
Concentrated oxidizing acids, hypochlorite-based cleaning agents, and peroxide-containing oxidizers are incompatible because oxidative chain scission breaks the polyvinyl alcohol backbone and lowers solution viscosity. Equipment cleaned with these materials must be rinsed to neutral pH and confirmed free of residual oxidizer before the product is reintroduced.
