Shuangxin 05-99 PVA (PVA 098-05)

Polyvinyl alcohol 05-99 from Shuangxin, also designated PVA 098-05, is a fully hydrolysed, low-viscosity vinyl alcohol homopolymer. The model string identifies a nominal degree of polymerisation in the 500 range and an alcoholysis degree near 99 mol%; the alternate four-digit code encodes the same polymer class. Shuangxin manufactures the grade to the GB/T 12010 series, and certificates of analysis typically report alcoholysis degree by GB/T 12010.2-2010, viscosity by GB/T 12010.3-2010 using an Ubbelohde viscometer, volatile matter by GB/T 12010.4-2010, ash by GB/T 12010.5-2010, and pH by GB/T 12010.6-2010. The polymer carries CAS 9002-89-5 and is water-soluble; however, because the alcoholysis degree is 98.0–99.0 mol%, dissolution requires heat input above 70 °C, unlike partially hydrolysed grades in the 86–89 mol% range that disperse in cold water.

In the as-received powder form, the grade is a white to off-white granule or powder. The lot release specification for viscosity is typically 4.5–6.0 mPa·s for a 4% aqueous solution at 20 °C, though lot-specific certificates of analysis should be consulted because Shuangxin may report against an internal method aligned to GB/T 12010.3-2010. Volatile matter is normally controlled at ≤5.0%, ash at ≤0.5%, and pH of a 4% solution at 5.0–7.0. Residual acetyl content is below 2.0 mol%, measured as saponification-released acetic acid. Published data for Shuangxin-certified lot-to-lot variance for this specific grade is limited; the above ranges reflect the general 05-99 class and should be verified against the supplier’s certificate.

What Controls Dissolution Behaviour and Solution Handling?

The main process conflict in using fully hydrolysed PVA 05-99 is that its high crystallinity, resulting from the 98–99 mol% alcoholysis degree, raises the minimum dissolution temperature while the low polymerisation degree shortens the molecular weight distribution tail. In production-scale kettles, powder is pre-slurried in deionised water at 10–25 °C with a turbine agitator tip speed of 3–5 m/s to wet the particles, then heated to 85–95 °C and held for 30–60 min. If the slurry is heated too quickly before the powder is fully swollen, gel particles form on the liquid surface and on the kettle wall; these particles are not removed by a 100 mesh filter but will blind a 200 mesh screen. The solution should be cooled under low shear to 40–50 °C before transfer to storage, and viscosity drift during extended hold at 90 °C is usually caused by microgel aggregation rather than molecular weight degradation; nitrogen blanketing may be used if colour stability is critical. The process boundary for this grade is therefore a minimum dissolution temperature of 85 °C; below 80 °C, solution clarity may appear acceptable yet film defects appear later in casting or sizing.

Solution compatibility boundaries should be observed. The fully hydrolysed grade is not compatible with strong mineral acids, which catalyse dehydration and insolubilisation; borate salts, which form stiff complexes; and high concentrations of polyvalent metal ions, which reduce shelf life. Glyoxal or dialdehyde crosslinkers can be added at 0.5–2.0 wt% on PVA solids to improve water resistance of paper coatings, but gel time depends on pH; buffering at pH 4–5 is typical for controlled pot life. At pH> 8, the solution may discolour during prolonged heating. These boundaries are not unique to Shuangxin 05-99 but are more critical because the high alcoholysis content provides fewer acetate substituents to interrupt borate crosslinking.

In remoistenable adhesive and paper converting, 05-99 is typically formulated as a 5–10 wt% aqueous solution with plasticisers or dextrin. The fully hydrolysed polymer imparts higher wet bond strength and lower moisture sensitivity than partially hydrolysed 05-88. Application viscosity at 25 °C for a 5 wt% solution is commonly below 150 mPa·s when measured by Brookfield viscometer at 20 rpm; this allows clean roll-coating on kraft paper. Film tensile strength of solution-cast specimens conditioned at 23 °C and 50% RH is reported in polymer film literature at 40–60 MPa, with elongation at break 150–250%, when tested per ASTM D882-18. Users should verify exact film properties on their own substrate because fillers, defoamers, and drying profiles change crystal development. The product is not a cold-water grade; mixing into process water below 70 °C yields an opaque dispersion, not a true solution.

Textile warp sizing is a major application. A size mix containing 4–6 wt% 05-99 and native or modified starch is applied to spun cotton and polyester/cotton warps. The PVA contributes film strength and abrasion resistance on high-speed looms; the low DP keeps size-box viscosity low enough for jet cooking and reduces starch retrogradation compared with 17-99. Desizing of the fully hydrolysed grade requires hot water above 80 °C or an oxidant-based desizing agent; partially hydrolysed grades are removed faster at lower temperatures. The narrow viscosity specification of 4.5–6.0 mPa·s supports size add-on control within ±0.5% absolute on a slasher, provided the cook temperature stays at 90 ± 5 °C. For air-jet weaving of Ne 40 cotton, size add-on values of 8–12% are typical, but published data for this specific product in textile field trials is limited; trials should include weave-room humidity at 70–80% RH to prevent size film brittleness.

If the Formulation Requires Low-Temperature Processing, a Partially Hydrolysed 05-88 Grade Is Preferred

The difference between 05-99 and 05-88 lies in alcoholysis control. At 98–99 mol%, interchain hydrogen bonding is strong enough to require thermal energy for disruption; at 86.5–89.0 mol%, residual acetate groups reduce crystallinity and permit solution preparation in water at 20–30 °C. The trade-off is water resistance: films from 05-99 show lower swelling after 24 h water immersion than those from 05-88. In adhesion to hydrophobic substrates, the fully hydrolysed grade generally produces higher ultimate tensile strength but lower tack and slower open time. Therefore 05-99 is selected when the downstream process can accommodate a 85–95 °C cook step and the final article requires moisture resistance; 05-88 is selected when cold or ambient processing is compulsory and re-moistenability is acceptable.

Property Differences Among Grades Are Driven by Alcoholysis and Viscosity

Table 1 compares the class-range specifications of 05-99 with two common alternatives. The values are typical public technical data for PVA grades in the same test framework; Shuangxin lot-specific certificates may vary within the stated ranges.

Because PVA degrades at temperatures close to its crystalline melting point, 05-99 is not melt-processable as a pure polymer without plasticiser. Water, glycerol, or polyol plasticisers lower the processing temperature enough for film extrusion. In blown film, a water-plasticised PVA pellet or pre-compounded masterbatch is used on a single-screw extruder with a compression ratio of 3:1 and barrel temperatures below 190 °C. Residual water is controlled to 15–30 wt% in the feed, and venting is required to avoid steam pressure instability. The low-viscosity grade is less prone to shear overheating than 17-99 but may require a higher plasticiser level or a narrower die-temperature band to maintain bubble stability.

On a twin-screw extruder used for PVA compounding, the low-viscosity grade may require careful liquid injection because it wets slowly and can form cavitation bubbles if the plasticiser is injected too early. Published data for this specific configuration is limited; compounding trials should begin with liquid injection downstream of the first kneading block and a screw speed ramp from 100 rpm to 300 rpm to prevent overtorque. The product’s low ash content reduces screw wear relative to filled PVA compounds.

The nominal degree of polymerisation of 500 does not appear directly on certificates; instead, viscosity is a proxy. The relationship between intrinsic viscosity and viscosity-average molecular weight can be described by the Mark-Houwink equation, but routine release uses the empirical 4% solution viscosity. Low-DP fully hydrolysed grades such as 05-99 exhibit lower shear sensitivity than high-DP grades because the chain length is below the entanglement threshold at typical use concentrations. This is advantageous in high-speed coating where high shear reduces dynamic viscosity predictably.

Specification Compliance Matrix and Test Designations

Table 2 lists the principal release parameters and the test designations that should appear on a certificate of analysis. If a parameter is not reported, the user should request it before qualifying the grade for food-contact or pharmaceutical use.

In paper surface sizing, 05-99 is used at 0.5–2.0 wt% solution. The low solution viscosity permits size-press pickup at higher solids than high-DP grades. IGT surface strength improvements can be measured according to ISO 3783 or TAPPI T 499; the increase depends on base paper and drying. The fully hydrolysed grade provides oil resistance and reduces dusting. However, if the paper machine has a flooded nip size press with short contact time, undissolved gel particles from incomplete cooking cause blade scratches; a 100 mesh inline filter is recommended.

For food-contact applications, the grade should be qualified under 21 CFR 177.1670 for polyvinyl alcohol film or 21 CFR 176.170 and 21 CFR 176.180 for paper and paperboard components, as applicable. Migration limits under EU 10/2011 apply to finished articles; the supplier should provide a compliance statement for residual vinyl acetate monomer, sodium acetate, and methanol. For pharmaceutical topical films, published data for this specific Shuangxin grade is limited, so a supplier audit and lot-specific extraction profile are required.

Powder storage should be below 30 °C and at relative humidity below 60% to prevent caking; if exposed above 60% RH, the powder may absorb moisture and bridge in screw feeders. Pre-drying is not normally required unless the powder is to be dry-blended with moisture-sensitive additives. Bags should be kept sealed because the product is hygroscopic and may develop lumps that are harder to disperse. Dry powder conveying systems should be grounded to avoid electrostatic discharge, and dust collection should be designed for a Kst value verified in accordance with ASTM E1226.

In sustainability-related assessments, the low ash specification of ≤0.5% and the absence of intentionally added halogen-bearing additives simplify material declarations. RoHS does not apply to PVA as a polymer unless the finished electrical article incorporates the material, in which case the inorganic residue should be included in the article-level declaration. The grade is not intended for direct consumer use as an ingredient and should be handled with dust control consistent with combustible organic powder processing.