| HS Code | 165674 |
| Product | Wanwei PVA 20-92(L) (PVA 092-35) |
| Chemical Name | Polyvinyl alcohol |
| Cas Number | 9002-89-5 |
| Appearance | White powder or granular |
| Degree Of Hydrolysis | 92.0 ± 1.0 mol% |
| Viscosity 4 Solution 20c | 30.0 - 40.0 mPa·s (nominal 35 mPa·s) |
| Average Degree Of Polymerization | 2000 |
| Ph 4 Solution 20c | 5.0 - 7.0 |
| Volatile Content | ≤ 5.0% |
| Ash Content | ≤ 0.5% |
| Bulk Density | 0.4 - 0.6 g/cm³ |
| Particle Size | 20 - 80 mesh |
| Solubility | Soluble in water |
As an accredited Wanwei PVA 20-92(L) (PVA 092-35) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 20 kg net polyethylene-lined woven polypropylene bags, sealed to protect against moisture, ensuring safe handling and storage. |
| Container Loading (20′ FCL) | 20′ FCL: Wanwei PVA 20-92(L) packed in palletized bags, securely stowed, moisture-protected, and container sealed for safe transit. |
| Shipping | Wanwei PVA 20-92(L) ships as non-hazardous polyvinyl alcohol powder. It must be kept dry, as it is hygroscopic. Use sealed, moisture-resistant bags or containers, protect from puncturing, and store away from humidity and direct rain. Standard freight is suitable, but avoid contamination with dust-generating materials. |
| Storage | Store Wanwei PVA 20-92(L) in a cool, dry, well-ventilated area away from heat, sparks, and direct sunlight. Keep the original container tightly sealed to prevent moisture absorption and contamination. Avoid dust accumulation and contact with strong oxidizers. Use appropriate personal protective equipment when handling, and follow all local regulations for safe storage. |
| Shelf Life | Shelf life is 12 months from manufacture when stored in original sealed packaging in a cool, dry place. |
In the production of polyvinyl acetate homopolymer and vinyl acetate-ethylene copolymer dispersions intended for wood assembly adhesives, Wanwei PVA 20-92(L) (alias PVA 092-35) functions as the primary steric stabiliser. The polymerisation adopts a semi-continuous pre-emulsion feed regime within a glass-lined jacketed reactor equipped with a 45°-pitch impeller and baffles. An initial reactor charge of deionised water and 4–8 wt% PVA 20-92(L) (on total monomer mass) is heated to 75–80 °C. Non-ionic surfactant is optionally dosed at 0.3–1.0 wt% to modulate particle nucleation without completely replacing the polymeric colloid, as total surfactant substitution leads to a lost shear-stress plateau in the final adhesive.
Monomer pre-emulsion containing vinyl acetate monomer, the shell of a redox initiator system (typically potassium persulphate/sodium metabisulphite), and buffer solution is metered in over 3–4 hours. The process control variable most tightly coupled to PVA grade is the minimum film-forming temperature of the finished emulsion, which shifts non-linearly when the residual polyvinyl alcohol acetate distribution broadens. Users report that dropping the PVA 20-92(L) charge under 3.5 wt% on monomer triggers secondary nucleation bursts, yielding a bimodal particle size distribution detectable by disc centrifuge photosedimentometry ISO 13318. The emulsion is cooled and post-stabilised with a biocide package before drumming. Industry compliance framework: FDA 21 CFR 175.105 (adhesive components in indirect food contact), GB 18583-2008 (limits for free formaldehyde and volatile organic compounds in interior architectural adhesives), and qualitative identity under EU REACH Regulation (EC) No 1907/2006. Terminal end-products include D3/D4 wood bonding adhesives (as classified by EN 204), paper lamination glue, and bookbinding hot-melt adhesives where the dispersion substitutes for bulk acrylic systems.
Operational incompatibility: direct addition of borax (sodium tetraborate) or boric acid to the colloid-stabilised emulsion causes an immediate and irreversible viscosity climb exceeding 50,000 mPa·s due to cross-bridging of the 1,3-diol units on the PVA backbone. Manufacturers running a ‘borated’ thickening step must pre-dilute borax to 0.5% solution and dose under high agitation; without this, induction period shortening in subsequent storage stability tests (ISO 13032-2) is observed.
On a Benninger Supertronic SMR-2 two-cylinder pre-wet sizing range processing 40s Ne 65/35 polyester/combed cotton warp yarns for high-density down-proof shirting fabric at 800 m/min, PVA 20-92(L) is the dominant filming binder in the size liquor. The volume of medium is held at 920 L in the circulating system with a solids content of 10.5 ± 0.5 %. Formulation of the size box: 100 parts oxidised corn starch (fluidity 62 BF), 35 parts PVA 20-92(L), 8 parts polyacrylic size as lubricating component, and 2 parts winding oil, the balance water. PVA is dissolved in a separate heated cook tank at 95 °C for 45 min under propeller agitation before being commingled with gelatinised starch. Real-time control of size pick-up at 12–14.5 % (dry mass on yarn) is achieved by regulating squeezing roller pressure (12–16 kN for the first nip). Sizing viscosity at 90 °C is maintained between 28–35 mPa·s (Brookfield LV #21, 100 rpm); excursions above 40 mPa·s produce a brittle brittle size film with increased lint shedding at the reed. After drying cylinder surface temperature 125–140 °C, the sized beams demonstrate a hairiness index reduction of 62–78 % relative to unsized warp (Zweigle G565 tester). The finished fabric passes OEKO-TEX® Standard 100 Annex 4 limits for residual vinyl acetate monomer and formaldehyde. Terminal textiles include 80 × 80 / 230 × 195 down-proof taffeta and shirting poplin, where warp breakage rates on Tsudakoma ZAX9200i water-jet looms fell to 0.24 breaks per 100,000 picks in plant data logs.
When surface sizing high-brightness woodfree sheets on a Voith SpeedSizer with film-transfer metering, the replacing of a fraction of pigment coating binder with PVA 20-92(L) is driven by the requirement for IGT dry pick velocity above 3.5 m/s. The size press stock is prepared at 7.2 % solids and the portion of PVA 20-92(L) in the binder mix (predominantly styrene-acrylate latex and enzyme-converted starch) is tuned between 18–28 dry weight %. The liquor’s temperature at the blade is 62–68 °C. Viscosity stability across the blade is critical because partially hydrolysed PVA is more shear-stable than the alternative cationic starch but can undergo retrogradation-induced microgelation if the blade reservoir pH drifts below 5.0. For that reason, the wet-end additive programme must guarantee that the base paper’s surface pH exceeds 6.5.
The coating weight target is 1.2–1.8 g/m² per side, monitored through beta-ray or IR reflection gauges. Tuning the PVA 20-92(L) fraction above 30 dry weight % increases the dynamic water contact angle of the sized sheet beyond 85° after 10 s, which deteriorates the receptivity to water-based flexo ink on press, a phenomenon tracked via Emtec PDA.C 02 short-time measurement. Regulatory boundary: composition of the surface-sizing layer is subject to FDA 21 CFR 176.170 (components of paper and paperboard in contact with aqueous and fatty foods) and BfR Recommendation XXXVI. The finished outputs are 90 g/m² SBS folding cartonboard for dry food packaging and 128 g/m² C1S art paper for offset lithography, where the PVA fraction in the surface size recipe raised Dennison wax pick values by 2–3 units in mill qualification trials.
PVA 20-92(L) exhibits a cold-water dissolution spectrum that enables continuous cast film production for unit-dose applications without requiring a post-coating crosslinking step. The film stock is fabricated on a caterpillar-track conveyor solution-casting line with co-rotating L/D = 36 twin-screw extruder degassing of the aqueous PVA dope. The aqueous solution is prepared at 19–22 wt% PVA 20-92(L) with 15–20 parts of a plasticiser blend (glycerol/sorbitol/xylitol) per 100 parts resin, 0.5–1.2 wt% of release agent, and quaternary ammonium salt as anti-block modifier. A series of static mixers after the extruder head ensures that gel counts detected by inline 50 μm mesh screen remain below 5 particles per 10 m² of finished film. The casting curtain is spread onto a chromium-plated steel belt moving at 8–18 m/min and progressed through five drying zones from 65 °C (zone 1) to 108 °C (zone 5). Humidity profiling is critical: the feed section is held at 60 % RH to prevent skin-over, while the last zone exits at 12–14 % equilibrium moisture to avoid inter-layer blocking during wind-up.
In quality control, dissolution time—measured as the time for complete disintegration of a 76 μm-thick, 25 mm × 25 mm film coupon in 1 L deionised water stirred at 200 rpm at 20 °C—must fall within 22–36 s. In the pH range of commercial laundry liquid detergents (7.5–8.5), no statistically significant drift in dissolution half-life is observed; however, high-alkaline formulas with pH above 10.5 cause progressive crystallisation-driven oligomer re-association that extends dissolution time beyond 120 s after 8‑week storage at 37 °C. Test standards tethered to final product claims: ISO 14851 (ultimate aerobic biodegradability), EN 17017:2018 for soluble detergent packaging sheets, and ISO 15270 when claimed as biodegradable plastics. End products include PVOH film encasing liquid laundry capsules, water-soluble agricultural chemical sachets, and release film for cast composite components.
Spray-dried polymer-bound dispersible polymer powders based on ethylene-vinyl acetate copolymers utilise PVA 20-92(L) as the primary colloidal armour during emulsion synthesis and again as a post-added spray-drying aid. In the upstream polymerisation reactor, the protective colloid demand is 5–7.5 wt% based on vinyl acetate plus ethylene monomer feed; subsequent dilution to 47 % solids precedes the atomisation step. Drying is executed on a NIRO MOBILE MINOR™-type co-current pressure nozzle tower with an inlet temperature of 185–205 °C and outlet temperature clamped at 83–87 °C. The critical boundary is the outlet temperature: exceeding 92 °C causes the PVA shell to thermally fuse, yielding non-redispersible grit that fails the EN 12004 mineral surface bond strength retention test after immersion. The powder is post-blended with 8–12 % fine SiO₂ anti-caking agent, then packed in moisture-resistant aluminium-foil bags. In the downstream dry-mix formulation—a C2TE S2 ceramic tile adhesive conforming to EN 12004:2007—the content of redispersible powder containing PVA 20-92(L) is 3.5–5.0 % on cement weight. Compound storability is limited to 6 months at 20 °C/50 % RH due to gradual plasticiser migration into hygroscopic filler particles.
In the non-aqueous tape-casting process for 96 % Al₂O₃ thin-film electronic substrates, the low-ash designation of PVA 20-92(L) (residual sodium < 200 ppm, residual iron < 50 ppm) meets the ionic cleanliness requirement for microwave dielectric laminates. The tape-casting slurry is blended in a planetary centrifugal mixer: 100 parts alumina powder (D₅₀ 0.8 μm), 35–45 parts MEK/ethanol azeotrope solvent system, 3.5–4.2 parts PVA 20-92(L) as sacrificial binder, 1.8–2.5 parts dibutyl phthalate plasticiser, and 0.4 parts phosphate ester dispersant. After deaeration under 20 mbar vacuum, the slurry is doctor-bladed onto silicone-coated PET carrier film at a gap of 200–280 μm and line speed of 0.5–1.2 m/min. Drying is executed in a two-zone convection channel with zone 1 at 50 °C and zone 2 at 70 °C, holding green tape moisture below 0.5 wt% before peeling.
The burnout profile is validated against DIN 51085-style thermogravimetry: linear ramp to 280 °C at 1 °C/min, hold for 60 min to volatilise plasticiser, then ramp to 600 °C at 3 °C/min and dwell for 120 min to oxidise the PVA backbone. Residual carbon measured by coulometric detection must fall below 0.04 wt%, otherwise co-fired silver-palladium conductor paste suffers blistering. The sintering step proceeds at 1,580–1,620 °C in an air atmosphere to reach ≥ 96 % theoretical density. A known limitation when using partially hydrolysed PVA binders is the increased hygroscopicity of the green tape: ambient exposure beyond 2 hours at RH > 55 % induces 3D swelling and via-hole misregistration exceeding ±0.15 mm on a 200 mm × 200 mm panel. Finished components include microstrip antenna substrates, thick-film hybrid circuit boards, and multi-layer ceramic capacitor (MLCC) dielectric sheets where the binding phase burnout behaviour directly influences loss tangent (tan δ) at 1 MHz per IEC 60384-8.
| Application | Input concentration of PVA 20-92(L) | Critical process window | Primary compliance code |
|---|---|---|---|
| PVAc/VAE emulsion protective colloid | 4–8 wt% on total monomer | 75–80 °C reactor temp; do not charge < 3.5 wt% to avoid bimodal PSD | FDA 21 CFR 175.105, GB 18583-2008 |
| Polyester/cotton warp sizing | 35 parts in size formulation with 100 parts starch | Squeeze pressure 12–16 kN; size liquor viscosity 28–35 mPa·s | OEKO-TEX® Standard 100 |
| Coated fine paper surface sizing | 18–28 dry wt% of total binder | pH at blade > 5.0; base sheet surface pH > 6.5 | FDA 21 CFR 176.170 |
| Water-soluble unit-dose film | 19–22 wt% in aqueous dope | Drying humidity zone 1: 60 % RH; final moisture 12–14 % | EN 17017:2018 |
| Spray-dried redispersible powder | 5–7.5 wt% on monomer; post-add in emulsion | Outlet air 83–87 °C; 92 °C triggers non-redispersible grit | EN 12004 |
| Tape-casting electronic ceramic | 3.5–4.2 parts per 100 parts Al₂O₃ | Burnout hold at 280 °C 60 min; green tape exposure < 2 h at RH 55 % | IEC 60384-8 (MLCC tan δ) |
An additional formulation note common to all aqueous PVA 20-92(L) mixtures: dry powder must be stored at < 30 °C and < 60 % RH. Solution preparation requires slow sifting of powder into a vortex of water at 20–25 °C followed by heating to 85–95 °C with constant agitation for at least 30 min; cold slug addition directly to hot water results in undispersed ‘fish-eye’ cores that resist full hydration and show up as micro-gels in sizing or coating operations.
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Wanwei PVA 20-92(L) — also distributed in certain regional markets under the designation PVA 092-35 — is a partially hydrolysed polyvinyl alcohol grade characterised by a nominal viscosity of 20–25 mPa·s (measured as a 4% aqueous solution at 20 °C per ISO 15023-2:2019) and a degree of hydrolysis controlled within 91.0–93.0 mol%. The residual acetyl content, determined by saponification value according to ISO 15023-1:2019, ranges between 100 and 120 mg KOH/g. Ash residue after ignition at 800 °C is specified at ≤0.5 wt%, and the pH of a 4% aqueous solution falls at 5.0–7.0. The powder exhibits a bulk density of 0.40–0.60 g/cm³ and passes a 80-mesh screen with ≥90% retention. This balance of medium molecular weight and controlled lipophilic character positions the grade as a multipurpose stabiliser, temporary binder, and film former in water-based industrial formulations, where full cold-water solubility and adequate intercoat adhesion are required without the excessive hygroscopicity of lower-hydrolysis grades.
In the manufacture of aqueous vinyl acetate-ethylene (VAE) copolymer dispersions in 10–25 m³ stirred stainless-steel reactors fitted with multi-stage impellers (80–120 rpm), PVA 20-92(L) functions as the primary protective colloid. Charged at 3–6 pphm (parts per hundred monomer) into a pre-emulsion along with a persulphate initiator at 0.2–0.5 wt%, the polymer chains undergo partial grafting reactions with the growing PVAc backbone, generating a steric barrier that controls both particle nucleation and coalescence. Industrial trials show that substituting a fully hydrolysed grade (e.g., 99+ mol%) with 20-92(L) depresses the final latex particle size distribution (PSD) from 800–1200 nm to 400–700 nm, as measured by dynamic light scattering (ISO 22412:2017). The lower acetoxy surface excess, expressed as the surfactant-to-colloid transition concentration, reduces the risk of foaming in the reactor headspace. However, the grafting efficiency is sensitive to the dissolved iron content in the vinyl acetate monomer; when Fe2+ exceeds 2 ppm, an induction period of 20–40 s followed by an exotherm overshoot of +8 °C has been recorded at commercial scale, necessitating the addition of 50–100 ppm EDTA tetrasodium as a metal chelator. The resulting dispersion’s shear-rate-dependent flow curve, fitted to a Carreau–Yasuda model, shows a zero-shear viscosity 5–15 Pa·s and a power-law index 0.35–0.45 at 25 °C, data points critical for designing downstream transfer pumping and filter screen packs.
Dewatering behaviour of size films was evaluated on a Benninger warp sizing line operating at 75 m/min. A 6% solids bath containing PVA 20-92(L) combined with a potato starch ether (1:1 w/w) exhibited a size pick-up of 10.5–11.2% on ring-spun cotton yarn (30 Ne). The residual acetate groups soften the film morphology, imparting a glass transition temperature (Tg) of 62 °C as determined by differential scanning calorimetry (ASTM E1356), 15 °C lower than that of a 98–99 mol% hydrolysed grade. This depression reduces lint shedding in the split rod zone and cutting rail by 30–45%, quantified by gravimetric lint collection over 5000 loom cycles. Nonetheless, the sensitivity to condensation-induced hydrolysis must be accounted for: size boxes held overnight at pH >9.5 by residual desizing enzymes from previous lot changes triggered a viscosity decay greater than 15%, highlighting the need for alkaline buffer removal prior to makeup.
Polyvinyl alcohol wood adhesives formulated with 20-92(L) typically contain 10–14 wt% of the polymer, together with a polyvinyl acetate emulsion, calcium carbonate filler (30–50 µm median particle size), and a plasticiser such as dibutyl phthalate or a citrate ester. Wet tack development, measured by a probe-tack tester (ASTM D2979-16) on a birch veneer substrate conditioned at 23 °C, 50 % RH, follows a profile that reaches 0.8 N/mm² within 12–18 s, then plateaus at 1.2–1.5 N/mm² after 60 s. The partially hydrolysed structure yields an open assembly time on a porous beech surface of 8–12 min at 20 °C — approximately 4–6 min longer than an equivalent 88 mol% grade, due to slower water release governed by hydrogen bonding. During hot pressing at 110 °C, 0.8 MPa for 3 min, the bond line remains cohesive; no phase separation between PVA and the filled PVAc phase has been observed by scanning electron microscopy at 2000× magnification. A documented processing constraint arises when urea-formaldehyde or melamine-formaldehyde hardeners are incorporated to meet D3 or D4 durability classification (EN 204/205): pre-reaction between the hydroxymethyl groups and the PVA hydroxyls can cause a gelation front inside the static mixer elements within 45 min at 30 °C, forcing a shift to two-component application ahead of the static mixer.
Solution-cast multilayer films incorporating an oxygen barrier interlayer of 20-92(L) deposited from 15 wt% aqueous solution on a Böhnhardt film stretching line display an oxygen transmission rate (OTR) of 12–18 cm³·mm/(m²·d·atm) at 23 °C, 0 % RH when measured per ASTM D3985-17. Raising the relative humidity to 50 % elevates the OTR to 35–50 cm³·mm/(m²·d·atm), a permeability penalty attributed to plasticisation of the amorphous phase by sorbed water, which disrupts the interchain hydrogen-bond network responsible for gas barrier function. In contrast, a fully hydrolysed grade (hydrolysis degree >99 mol%) delivers OTR values of 1–5 cm³·mm/(m²·d·atm) under identical dry conditions, but requires dissolution at 95–98 °C and subsequent cooling to 35–40 °C over 90 min to avoid gel particle formation — a processing window that 20-92(L) expands significantly, dissolving rapidly at 40–45 °C without need for a temperature ramp. This trade-off positions 20-92(L) where moderate barrier performance suffices but ambient-temperature handling of the casting solution is mandatory, such as in pharmaceutical strip packaging where the cast film is thermally laminated between two polyethylene layers with an ethylene-acrylic acid adhesive tie coating at 90 °C, conditions where pinholing due to PVA film brittleness is eliminated owing to the grade’s lower crystallinity (the X-ray crystallinity index determined by peak deconvolution of the 2θ = 19.4° reflection stays below 28%).
| Property | Method | 20-92(L) | 17-99 | 20-99 | 05-88 |
|---|---|---|---|---|---|
| 4% solution viscosity (mPa·s) | ISO 15023-2 | 20–25 | 25–30 | 21–26 | 4.5–6.5 |
| Hydrolysis degree (mol%) | ISO 15023-1 | 91.0–93.0 | 99.0–99.5 | 99.0–99.5 | 86.5–89.0 |
| Ash (wt%) | ISO 3451-5 | ≤0.5 | ≤0.5 | ≤0.5 | ≤0.5 |
| Film tensile strength (MPa) | ISO 527-3 | 44–52 | 60–70 | 58–68 | 28–35 |
| Elongation at break (%) | ISO 527-3 | 150–200 | 70–110 | 80–120 | >250 |
| Dissolution temperature (°C) | Internal method | 35–50 | 90–98 | 92–100 | 18–30 |
When 20-92(L) partially replaces oxidised corn starch in a coating colour destined for a blade coater running at 1200 m/min, the Brookfield viscosity at 100 rpm shifts from 1200 mPa·s to 800–950 mPa·s at the same solids content, allowing an increase in coating solids from 58% to 63% while maintaining a stable dynamic water retention value (AA-GWR, 1.5 bar) of 50–65 g/m². The IGT pick strength (ISO 3783) improves to 2.8–3.2 m/s, attributed to a binder migration pattern that concentrates the PVA near the surface during the drying phase of a short-dwell evaporation zone at 250 °C web temperature. The partially hydrolysed grade generates a surface film free of excessive water sensitivity: the Cobb60 water absorption (ISO 535) of the dried coating is 25–28 g/m², compared to 18–20 g/m² for a fully hydrolysed PVA and 42–48 g/m² for the starch-only reference. An acknowledged operational boundary is the interaction with optical brightening agents (OBAs) of the tetrasulfonated stilbene class; at addition levels above 0.4 wt%, the formation of a PVA–OBA charge-transfer complex causes a visible yellowing (Δb* > +2.5) upon exposure to UV light in accelerated weathering chambers (ASTM G154).
| Regulation | Scope | Status |
|---|---|---|
| EU 10/2011 (amended) | Plastic materials and articles intended to come into contact with food | Monomers/additives listed; specific migration limit (SML) of the polymer generally not required due to high molecular weight; residual vinyl acetate monomer < 2 mg/kg verified by HS-GC-MS per EN 13628-2. |
| FDA 21 CFR 175.300 | Resinous and polymeric coatings for food contact | Substance listed as component of coatings for repeated use; extractives limitation 0.5 mg/in² in food-simulating solvents D, E, and F. |
| FDA 21 CFR 176.170 | Components of paper and paperboard in contact with aqueous and fatty foods | Component of sizing additives; GMP compliance requires extractives not to exceed 0.5 mg/in² for paper and paperboard. |
| FDA 21 CFR 177.1670 | Polyvinyl alcohol film for dry food contact | Permitted subject to maximum water-extractable fraction specifications; PVA grade with viscosity >5 mPa·s acceptable. |
| REACH (EC) 1907/2006 | Registration, Evaluation, Authorisation of Chemicals | Polymer exemption applied; registration not required per REACH Article 2(9). Monomer VAM registered; supplier has confirmed SVHC content below 0.1% w/w. |
| RoHS 2011/65/EU | Restriction of hazardous substances in electrical and electronic equipment | Not in scope for the polymer itself; cadmium, lead, mercury, chromium VI, PBBs/PBDEs below threshold if used as processing aid in EE applications. |
Material stored in open bags at ambient conditions exceeding 30 °C and 80 % RH for >72 h will exhibit lump formation and a moisture uptake of 3–5 wt%, which introduces feeding inconsistencies in gravimetric screw dosing systems (e.g., Brabender or K-Tron singe-screw feeders with D=20 mm, L/D 22:1) and requires pre-sieving through a 1.4 mm mesh. Stock solutions held without biocide at 20–25 °C exhibit a mould growth onset visible to the unaided eye after 5–7 days; addition of 0.05–0.1 wt% of a methylisothiazolinone/benzisothiazolinone blend (3:1 ratio) extends fluid service life to 90 days. Crosslinking of 20-92(L) solutions with glyoxal at molar aldehyde-to-hydroxyl ratios above 0.15 should be avoided in formulations that will be stored at pH <4.0, because the rapid formation of cyclic acetal structures increases the viscosity beyond the point of spray atomisation (>200 mPa·s) within 30 min, rendering the delivery system inoperable.
When used as a carrier resin in ceramic body extrusion, addition of 2–4 wt% 20-92(L) (based on dry ceramic mass) reduces the plasticity index of an alumina slip (prepared from A-16 SG powder, surface area 9.5 m²/g) from 28 mm to 17–19 mm (Pfefferkorn method), while retaining a green strength of 1.8–2.5 MPa measured by 3-point bending according to ASTM C1161. The sintering burnout profile demands a heating ramp in air to 600 °C at a rate of 0.5 °C/min between 180 °C and 280 °C, the interval where the exothermic decomposition of the residual acetate groups takes place; exceeding 1 °C/min in this zone has caused blistering and delamination of extruded honeycomb catalyst substrates observed in production-scale tunnel kilns.
