Sinopec PVA 088-17 is a partially hydrolyzed polyvinyl alcohol (PVOH) grade with an intermediate degree of hydrolysis and a medium‑low solution viscosity. The manufacturer’s designation encodes this architecture: the first three digits denote a nominal degree of hydrolysis of
88 mol%, while the suffix
17 corresponds to a 4 % aqueous solution viscosity centered at
17 mPa·s when measured at
20 °C per
JIS K6726 or
ISO 15023‑2. The residual acetate groups produce a polymer that dissolves readily in cold water and exhibits balanced surface activity, making it suitable as a protective colloid, film former, and binder across a range of aqueous processing platforms. Typical batch‑release specifications, verified by Sinopec quality certificates, list a hydrolysis range of
87.0 – 89.0 mol%, a 4 %‑solution viscosity of
16.0 – 18.0 mPa·s, pH
5 – 7, ash content ≤
0.5 %, and volatile matter ≤
5.0 % after drying at
105 °C for
3 h. The powder form appears as white to off‑white granules with a bulk density of approximately
0.4 – 0.6 g cm⁻³ and a particle size distribution where
≥90 % passes a
20‑mesh sieve. Residual sodium acetate, a by‑product of the saponification step, is typically held below
0.2 % because elevated carryover can catalyze thermal yellowing in downstream hot‑melt compounding.
Typical property envelope for Sinopec PVA 088-17
| Property | Method | Range or Limit |
|---|
| Degree of hydrolysis | JIS K6726 /ISO 15023‑2 | 87.0 – 89.0 mol% |
| 4 % solution viscosity (20 °C) | ASTM D3591‑17, Brookfield LV | 16.0 – 18.0 mPa·s |
| pH (4 % aqueous) | JIS K6726 | 5 – 7 |
| Ash (as Na₂O) | JIS K6726 | ≤0.5 % |
| Volatile matter | JIS K6726 (105 °C, 3 h) | ≤5.0 % |
| Residual sodium acetate | Potentiometric titration | ≤0.2 % |
| Bulk density | Scott volumeter | 0.4 – 0.6 g cm⁻³ |
In emulsion polymerization, a platform where 088-17 frequently functions as the primary protective colloid for vinyl acetate‑based latices, the degree of hydrolysis directly governs the hydrophilic‑lipophilic balance (HLB) and thus the steric stabilization efficiency. Processes employing a continuous stirred‑tank reactor (CSTR) train with a residence time distribution centered at
45 – 90 min and a jacket‑controlled temperature of
65 – 75 °C show that addition rates of
0.3 – 1.0 wt% (monomer basis) of 088-17 yield latex particles with a z‑average diameter of
150 – 350 nm as measured by dynamic light scattering. When the chosen grade shifts toward a fully hydrolysed homolog such as PVA 1799 (hydrolysis ≥
98 mol%), the colloid becomes more hydrophobic; nucleation shifts, leading to a broader particle size distribution and often an unacceptable increase in coagulum on reactor walls. Conversely, lower‑viscosity partially hydrolysed grades such as 088-05 (viscosity ~
5 mPa·s) provide inferior shear stability during polymerization and can cause excessive foam formation due to their smaller molecular weight, demanding additional defoamer and complicating post‑polymerization stripping.
How does 088-17 compare with 088-20 and 1799 in water‑soluble film applications?
Water‑soluble film intended for unit‑dose detergent packaging or agrochemical sachets demands a specific dissolution profile and mechanical integrity. Sinopec 088-17, 088-20, and 1799 span three distinct property spaces. In cast film trials on a pilot‑scale coating line with a die gap of
0.5 mm, a drying tunnel temperature of
120 °C, and a line speed of
3 m min⁻¹, films prepared from 088-17 exhibit a dissolution time of
50 – 70 s in water at
20 °C (film thickness
50 µm), whereas 088-20 (viscosity ~
20 mPa·s) extends dissolution to
80 – 100 s, and fully hydrolysed 1799 requires water temperatures above
40 °C for complete dissolution within
120 s. Tensile strength tests per
ASTM D882‑18 reveal that the 088-17 film achieves a break strength of
35 – 45 MPa with an elongation at break of
250 – 350 %; the 088‑20 film is marginally stronger (
40 – 50 MPa) but less extensible (
200 – 280 %), while the 1799 film is brittle unless heavily plasticized with
10 – 15 wt% glycerol, at which point tensile strength drops to
25 – 35 MPa. For packaging dry products that must dissolve quickly in cold water, 088‑17 is preferred; when a slightly slower dissolution and higher hot‑water resistance are required, 088‑20 is chosen. The fully hydrolysed grade is rarely used for cold‑water‑soluble films without co‑blending.
Compounding Window and Solution Preparation Constraints
The dry powder absorbs ambient moisture rapidly. In production environments where relative humidity exceeds
60 %, pre‑drying in a dehumidified‑air hopper dryer at
60 – 70 °C for
2 – 4 h is necessary to prevent lumping in volumetric feeders and to maintain consistent mass flow into continuous dissolution equipment. For aqueous dissolution, the recommended procedure is to charge
4 – 10 wt% of powder into cold water under high‑shear mixing (e.g., a rotor‑stator disperser with a tip speed>
15 m s⁻¹), then heat the slurry to
90 – 95 °C with gentle agitation for
30 – 60 min until a clear solution is obtained. Prolonged heating above
95 °C in the presence of residual alkali can darken the solution and reduce adhesive performance. Viscosity is strongly pH‑dependent: below pH
4, acid‑catalysed acetal formation can occur if aldehydes are present, whereas above pH
10 the solution thickens due to partial hydrolysis of residual acetate groups, a drift that must be accounted for in extended coating campaigns.
In paper and paperboard coating, 088-17 is dosed as a sole binder or in combination with starch at a total binder level of
3 – 6 parts per 100 parts of pigment. Trials on a multi‑station blade coater operating at
800 m min⁻¹ with a coating colour solids content of
60 % demonstrate that substituting
50 % of the oxidized starch with 088-17 increases surface strength as measured by the IGT pick test (
ISO 3783:2015) by
25 – 40 % while reducing binder migration. The high‑shear rheology is critical: a plate‑and‑cone rheometer sweep from
0.1 s⁻¹ to
10⁵ s⁻¹ shows that the PVA‑containing colour retains a lower apparent viscosity under blade‑pressure conditions, lowering the risk of stalagmite‑type coating defects. However, the partial hydrolysis level of 088-17 means the binder film is more sensitive to water rewetting than a fully hydrolysed PVA; for offset printing grades, a water‑resistance additive such as glyoxal at
0.5 – 1.0 wt% (based on PVA solids) is often post‑added.
Comparative property profiles of selected Sinopec PVA grades
| Grade | Hydrolysis (mol%) | Viscosity (mPa·s, 4 %) | Typical 4 % dissolution T (°C) | Film tensile strength (MPa)* | Common application focus |
|---|
| 088-05 | 87 – 89 | 4.5 – 5.5 | ≤10 | 25 – 35 | Low‑viscosity protective colloid, emulsion stabilizer |
| 088-17 | 87 – 89 | 16 – 18 | ≤15 | 35 – 45 | Textile sizing, paper coating binder, water‑soluble film |
| 088-20 | 87 – 89 | 19 – 21 | ≤20 | 40 – 50 | Higher hot‑water resistance film, adhesive base |
| 1799 | ≥98 | 22 – 28 | >70 | 60 – 75 | Solvent‑borne adhesive, polarizer film, high‑barrier coating |
*Films cast from 10 % solution, conditioned at 23 °C /50 % RH, tested per
ASTM D882.
When 088-17 is deployed in textile warp sizing, the focus shifts to film flexibility, abrasion resistance, and ease of desizing. A typical size formulation contains
8 – 12 % PVA solids, optionally blended with
20 – 40 % starch to balance cost and performance. The size is applied on a multi‑cylinder slasher with a squeeze‑roll pressure of
2 – 4 bar and a drying‑can temperature profile spanning
110 – 135 °C. The intermediate viscosity of 088-17 produces a size pickup of
8 – 14 % (owf) on cotton yarn, generating a weaving efficiency improvement of
5 – 8 % relative to starch‑only size on a high‑speed air‑jet loom running at
800 – 1000 rpm. The partial hydrolysis ensures rapid desizing with hot water at
60 – 80 °C without enzymatic assistance, meeting the process demands of continuous preparation ranges. A frequent bottleneck arises when the dissolved polymer solution is held in a pre‑mix tank for more than
8 h: microbial growth can degrade the solution, producing a marked viscosity loss. In-house trials indicate that the addition of
0.05 – 0.1 % of a biocide based on isothiazolinone chemistry is required to maintain viscosity stability beyond a single shift.
In polyvinyl acetate (PVAc) wood‑adhesive compounding, 088-17 often competes with lower‑viscosity grades used as protective colloids in the latex synthesis step but can also be post‑blended as a rheology modifier. Pumping the finished dispersion through a gear pump at
40 °C and
50 bar back‑pressure reveals that an addition of
1.5 wt% of 088-17 (solution‑form) elevates the low‑shear Brookfield viscosity from
6000 mPa·s to
12 000 mPa·s (spindle 6,
20 rpm) without sacrificing the shear‑thinning index (n) below
0.35, thus preserving roll‑coating transfer efficiency. The partially hydrolysed grade must be avoided in systems where the adhesive will contact aluminium substrates in a moist environment because the residual acetyl groups promote hydrogen evolution and delamination under alkaline conditions; tests per
DIN EN 204 (durability class D3) show that after a
4‑h immersion in cold water, bond strength drops from
4.2 N mm⁻² to
1.5 N mm⁻² when aluminium is the counter substrate, whereas fully hydrolysed PVA 1799 maintains
2.8 N mm⁻².
When 088-17 Replaces a Fully Hydrolysed Grade in Suspension PVC Production
The suspension polymerisation of vinyl chloride monomer (VCM) relies on a combination of suspending agents to control droplet size and resin porosity. Primary agents typically include partially hydrolysed PVAs with a hydrolysis range of
70 – 80 mol%, but 088‑17 can serve as a secondary agent that modulates the surface charge and reduces particle coalescence at the early stages of polymerisation. In a
30‑m³ autoclave operating at
57 °C with a stirring speed of
120 rpm, simultaneous dosing of
0.03 wt% of 088‑17 together with
0.08 wt% of a low‑hydrolysis primary agent yields an S‑PVC resin with a cold plasticizer absorption (CPA) of
25 – 28 g/100 g and an average particle size (D₅₀) of
130 – 150 µm. Replacing 088‑17 with a fully hydrolysed grade such as 1799 in the same protocol increases the median particle size to
180 – 220 µm and narrows the porosity distribution, causing a CPA drop below
20 g/100 g that is unacceptable for flexible PVC processing. The presence of residual acetyl groups in 088‑17 is critical to prevent excessive surface activity and thereby avoid the generation of sub‑
50 µm fines that clog dryer bag‑house filters.
A distinct application domain is temporary protective films and lapping tapes where controlled adhesion to stainless steel or glass is required. A formulation comprising
5 % 088‑17,
2 % glycerin, and
0.2 % surfactant, knife‑coated onto a corona‑treated polyethylene terephthalate carrier, generates a
15‑µm dry film with a
180° peel adhesion of
0.5 – 1.2 N/25 mm (
ASTM D3330‑22) on borosilicate glass. The low adhesion is not attainable with higher‑viscosity PVA grades because they produce thicker, stiffer films that require excessive peeling force. The moderate degree of hydrolysis also ensures the film can be removed cleanly with warm water without leaving haze, satisfying end‑user demands in electronics assembly.
Regarding global compliance, Sinopec PVA 088‑17 meets the monomer and heavy‑metal residual limits of
EU Regulation (EC) No 1935/2004 for food contact materials and has been registered under
REACH (EC) 1907/2006. It falls under FDA
21 CFR §175.105 (adhesives) and
§176.170 (components of paper and paperboard in contact with aqueous and fatty foods) when used within the specified migration limits. The product also satisfies the restricted substance requirements of
RoHS 2011/65/EU, with lead, cadmium, mercury, hexavalent chromium, PBBs, and PBDEs all below the analytical detection thresholds of
0.01 % (by weight). For exporters, compliance with
GB 9685‑2016 (China National Food Safety Standard for Uses of Additives in Food Contact Materials and Articles) is confirmed for packaging‑related applications.
Limitations that demand attention during specification selection include the material’s rapid moisture uptake; unless resealed immediately after use in a humidity‑controlled environment, the powder can gain
0.5 – 1.0 % moisture per hour at
50 % RH and
23 °C, altering the effective solids content in metered formulations. The polymer is incompatible with concentrated nitric acid, strong oxidising agents, and primary amines under heat, which can trigger crosslinking. In adhesive blends with starch, a cooking temperature exceeding
95 °C for more than
90 min leads to hydrothermal degradation that cuts the 4 %‑solution viscosity of the blend by
15 – 25 % relative to a freshly prepared sample, a drift that must be compensated through higher binder add‑on or tighter process time limits.
