| HS Code | 368431 |
| Chemical Name | Poly(vinyl alcohol) |
| Cas Number | 9002-89-5 |
| Molecular Formula | (C2H4O)n |
| Appearance | White to light yellow granular powder |
| Degree Of Hydrolysis | 99.0 - 100.0 mol% |
| Degree Of Polymerization | 900 |
| Viscosity 4 Solution 20 C | 8.0 - 12.0 mPa·s |
| Ph 4 Solution | 5.0 - 7.0 |
| Ash Content | ≤ 0.5 wt% |
| Volatile Content | ≤ 5.0 wt% |
| Density | 1.19 - 1.31 g/cm³ |
| Melting Point | 180 - 230°C |
| Solubility | Soluble in hot water above 80°C; insoluble in common organic solvents |
| Typical Molecular Weight | About 40,000 |
As an accredited PVOH 990E factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PVOH 990E is supplied in 25 kg multi-wall paper bags with an inner plastic liner, palletized and shrink-wrapped for safe transport. |
| Container Loading (20′ FCL) | PVOH 990E in 25kg bags loaded into a 20ft FCL container, securely stowed and protected for safe transport. |
| Shipping | PVOH 990E ships as a non-hazardous, water-soluble polymer powder in sealed multi-layer bags or FIBCs. Keep dry, avoid moisture, dust, and extreme heat during transit. Store in ventilated containers away from incompatible materials. Use clean, covered transport to prevent contamination and preserve product integrity. |
| Storage | Store PVOH 990E in its original, tightly sealed container in a cool, dry, well-ventilated area. Keep away from moisture, direct sunlight, heat sources, and strong oxidizers. Avoid generating dust; keep containers off the floor and separate from incompatible materials. Under proper conditions, shelf life is typically 24 months. |
| Shelf Life | Shelf life: 2 years from manufacture when stored in original, unopened containers under cool, dry conditions. |
Production-scale warp sizing of Ne 60/1–Ne 80/1 combed cotton for air-jet weaving routinely encounters end-break rates exceeding 0.8 breaks/10⁵ weft insertions when size add-on falls below 11%. PVOH 990E, with a degree of hydrolysis above 99.2 mol% and a 4% solution viscosity above 25 mPa·s (DIN 53015, Höppler method), builds a continuous film that bridges fibre-to-fibre contact points under high reed-beat forces.
Typical cook formulation in a 1 200 L jet-cooker at a single-end sizing line: 95 kg PVOH 990E dispersed in 900 L soft water at 18–25 °C, heated to 85 °C over 45 min and held for 90 min at 95 °C with mechanical agitation at 800 rpm. No external plasticiser is required; film elongation at break stays at 180% (ASTM D882-18) without the migration risk that glycerol introduces. For spun yarns with a high percentage of immature cotton, 4.5 kg of a starch ether (e.g., carboxymethyl starch, DS 0.25–0.35) may be dry-blended before dispersion to reduce film brittleness at low loom shed humidity. The size solids in the supply tray is maintained at 9.8–10.2%, temperature at 88±2 °C, and pick-up is controlled between 10.5% and 12.0% OWF via a double-nip squeeze roller with a linear pressure of 4.5 daN/cm.
When the warp sheet enters the pre-drying zone on a 9-cylinder multi-can dryer, first-can surface temperature is set to 125 °C, gradually declining to 105 °C on the final can, giving a residual moisture of 3.5–5.5%. Shed splitting is performed after drying; a 10 mm lease rod separation measured directly in front of the heald frames is mandatory to prevent adjacent-end adhesion. The finished beam diameter of 800 mm commonly carries 1 200–1 500 ends, supplied to air-jet looms running at 1 050 rpm with a shed humidity set point of 68–72% RH. End-product conformity references Oeko-Tex Standard 100 product class I, because desizing depends only on hot water at 90 °C without enzymatic pre-treatment, and the desize waste COD contribution remains below 320 mg/L at a 1:20 liquor ratio.
Banknote and passport paper substrates printed with intaglio and UV-curable offset inks demand a surface with both high surface strength (IGT pick velocity above 2.5 m/s) and controlled Cobb60 water absorption (25–40 g/m²). A twin-roll size press running at 850 m/min applies a solution containing 5.0–7.5 wt% PVOH 990E combined with 1.2–2.0 wt% of a styrene-acrylate surface-sizing agent (Tg ≈ 20 °C) and 0.3 wt% ammonium zirconium carbonate (AZC) as a water-soluble crosslinker that activates during the dryer section at 110–130 °C surface temperature. The pick-up on a dry base paper of 85 g/m² is held between 3.0 g/m² and 4.5 g/m² per side.
At a size-press nip pressure of 35 kN/m and a puddle temperature of 55–60 °C, PVOH 990E forms a coherent film that seals surface fibres while maintaining a PPS roughness (ISO 8791-4) below 1.8 μm, a parameter critical for subsequent holographic patch application. The surface-sizing operation is judged by the dry-pick resistance under IGT tester (ISO 3783) and by the reduction in deionised water drop absorption time from 0.8 s (unsized) to values above 120 s. Compliance with FDA 21 CFR 176.170(c) (table I, condition of use C) and BfR Recommendation XXXVI ensures the sized paper is admissible for dry food contact without functional barrier coatings when the total migration limit of 10 mg/dm² is not exceeded.
Industrial-scale runs at 4 000 mm deckle width demonstrate that replacing fully hydrolysed starch with PVOH 990E eliminates paper dust build-up on flexographic plate edges, reducing press cleaning cycles from every 12 000 to every 35 000 impressions. The final security substrate typically enters intaglio printing at absolute moisture content of 5.0±0.5%; any deviation above 6.5% triggers curl issues that disturb the sheet-fed registration tolerance of ±0.15 mm.
The dissolution of PVOH 990E in demineralised water at 85–90 °C produces a clear solution with a Brookfield LVF viscosity (20 rpm, spindle #2) of 320–480 mPa·s at 18% solids. This solution blanketed onto a chill roll at 4 °C and then dried across a 6-zone convection oven yields cast water-soluble film used in unit-dose laundry detergent pods. The film thickness is controlled to 76±3 μm and dissolution time in 10 °C water is benchmarked against MSTM 205 (MonoSol Test Method) at below 45 s, a property governed by the near-complete hydrolysis of PVOH 990E that prevents cold-water gelation. A proprietary plasticising blend of glycerol and sorbitol at a combined 9–13 phr (per hundred resin) is compounded into the aqueous mass before casting to achieve an MD tensile strength of 45–55 MPa and strain at break above 250% (ASTM D882).
Film production on a 2.2 m wide cast line with in-line corona treatment at 1.5 kW output requires residual moisture to be held between 2.5% and 3.5%. Exceeding 3.8% triggers blocking on jumbo rolls wound at 800 N/m tension. Converters die-cut the film into unit-dose pouches that are filled with liquid nonionic surfactant content up to 75% active; the PVOH 990E grade demonstrates migration resistance such that peroxide-based bleach components show less than 0.5% activity loss after 12 months at 30 °C per accelerated aging protocol IATA DGR 4.2. Final article conformance to EU Detergent Regulation 648/2004 on water-soluble packaging and to ISO 14021 for claimed biodegradability depends on PVOH 990E film achieving over 90% mineralisation in a 56-day Sturm test (OECD 301B).
When polyvinyl butyral (PVB) resin is plasticised with triethylene glycol bis(2-ethylhexanoate) at 32 phr to produce the interlayer for laminated safety glass, addition of 0.8–2.5 wt% PVOH 990E powder as a compatibilising agent reduces the yellowness index (ASTM E313) after 1 000 h QUV-B exposure from 6.8 to below 3.2. The mechanism involves PVOH 990E scavenging residual free aldehyde from the butyralisation step; the highly hydrolysed backbone provides hydroxyl sites that add to unreacted butyraldehyde under the extrusion temperatures of 180–210 °C. Co-rotating twin-screw extrusion (KDT 58 mm, L/D 48:1) with an underwater pelletiser processes the dry blend at a melt temperature of 205±3 °C, a die pressure of 42–48 bar, and a specific mechanical energy input of 0.28 kWh/kg.
Sheet extrusion at 0.76 mm thickness requires chill-roll temperatures of 40 °C to prevent surface haze caused by premature crystallisation of the PVOH-rich domains. The resultant PVB sheet must exhibit a pummel adhesion of 4–6 (according to ESI/UL Internal Method 601) to float glass after autoclave lamination at 12 bar, 135 °C. Commercially, this application satisfies ECE R43 for automotive windscreens, where the residual stress in the glass (measured by Senarmont compensation) stays below 4 MPa after conditioning per ISO 12543-4 section 7.3.
In a 15 000 L continuous stirred-tank reactor for vinyl acetate‑ethylene (VAE) copolymer dispersions, PVOH 990E is introduced at 5.0–8.0 wt% relative to the monomer phase, together with 0.15 wt% hydrogen peroxide initiator and a reducing agent, maintaining a redox activation energy lower than 60 kJ/mol. The 99-series hydrolysis degree produces a grafting frequency of approximately 3–5 graft sites per polymer chain, determined by the residual acetate groups that act as chain-transfer points during the exothermic polymerisation at 68 °C and 6.0 MPa ethylene pressure. The resultant dispersion stabilised exclusively with PVOH 990E yields a solids content of 54–56% and a Brookfield RVT viscosity of 1 800–2 800 mPa·s (spindle #4, 20 rpm) at 25 °C.
Post-synthesis, the PVOH-grafted layer boosts aqueous calcium ion stability to above 50 mL of 10% CaCl₂ solution before coagulation, rendering the emulsion suitable for formulating D3 wood adhesives meeting EN 204/D3 durability classes without blending with post-added polyvinyl alcohol. Testing per ISO 9020:1994 for the woodworking sector confirms wet-bond strength on beech above 4.5 N/mm². Because PVOH 990E carries no alkylphenol ethoxylate surfactants, the dispersion complies with the voluntary emission restriction set by GEV-Emicode EC1 PLUS and with the German AgBB scheme for VOC emissions from interior building materials.
In tape-casting of 96% alumina substrate for thick-film circuits, a binder formulation comprising 3.5–5.0 wt% PVOH 990E solution (prepared at 14% solids in deionised water) combined with 2.0 wt% polyethylene glycol 400 and 0.3 wt% ammonium polyacrylate dispersant is milled with submicron alumina powder (D50 0.7 μm) in a high‑torque planetary mixer at 35 rpm for 60 min. The slip viscosity measured via parallel-plate rheometer at a shear rate of 100 s⁻¹ falls to 1.2–1.8 Pa·s, low enough for polishing through a 20 μm doctor blade gap onto a Mylar carrier advancing at 0.5 m/min.
Green tape drying proceeds through a 3-zone convection tunnel at 40/60/80 °C; the PVOH 990E binder provides a tensile strength after drying of 3.2 MPa (ASTM D638-14 type V specimen) and a TMA-determined thermal decomposition range of 290–340 °C in air, allowing clean burnout before the 1 520 °C co-firing step. The tape can be punched with carbide tooling into substrates measuring 50 mm × 50 mm with 0.25 mm diameter registration holes showing edge chipping below 15 μm. Final ceramic body displays a bulk density above 3.85 g/cm³ and a camber below 50 μm/25 mm, meeting the requirements of LTCC (low-temperature co-fired ceramic) processes adapted for alumina-based power modules. Substrate manufacturers reference DIN EN ISO 17872 for scribe-test adhesion of the conductive paste printed post-firing.
A floated film of PVOH 990E supported on a 40 °C water bath functions as the carrier for offset-printed transfer patterns applied to helmet shells and automotive interior trim. Five parts PVOH 990E are dry-blended with 1.0 part sorbitol-bis(2-ethylhexanoate) and 0.2 parts fumed silica, then extruded through a chill-roll line into film of 35±2 μm. The absolute dissolution time of the unsupported film on still water at 25 °C lies between 55 s and 70 s, measured by the moment the printed pattern floats free; this window is engineered through precise control of the film’s sodium acetate content below 0.8%, a by‑product of the polymerisation saponification stage.
During transfer, an activator spray containing iso-butyl acetate applied at 12 g/m² (wet) softens the ink within 18–25 s, after which the part is dipped through the floating ink at a constant incidence angle of 30°. Since no haze remains after curing at 80 °C, the process achieves a gloss level of 90+ GU at 60° (ASTM D523) on black ABS after a 2K urethane topcoat. Compliance with the automotive OEM specification TL 226 and GMW 3191 is validated via the cross‑hatch check (ISO 2409) showing class 0 adhesion.
Paper tube winders operating at 80–120 m/min with 6-ply construction apply a 40–44% solids adhesive composed of native corn starch (82 parts dry), 8 parts PVOH 990E solution at 20% concentration, and 1.8 parts borax decahydrate as a tack‑builder and crosslink‑promoter, processed in a 1 000 L Stein Hall cooker at 72 °C. The addition of PVOH 990E shifts the adhesive’s open time from approximately 22 s to 38 s at 50% RH (measured with a rotary tack tester at 23 °C), directly reducing tube delamination rates at the slitter to below 0.4%.
Bond strength is evaluated by Morgan crush test (TAPPI T 822); cores manufactured with this modified adhesive exhibit a radial crush resistance of 1 700–1 900 N per 100 mm length for an inner diameter of 76 mm and wall thickness of 8 mm. The adhesive formulation falls under FDA 21 CFR 175.105 for incidental food contact, as the PVOH 990E migrates into the paperboard at levels that do not exceed the detection limit when tested per the FDA “chemistry recommendation” for starch‑based adhesives in dry-food packaging cores.
| Parameter | Test method | PVOH 990E (10% size add-on) | Oxidised starch + acrylic (12% add-on) |
|---|---|---|---|
| Weaving stops / 10⁵ picks | DIN 53855 | 0.6–0.9 | 1.8–2.6 |
| Desizing of COD (mg O₂/L) | DIN 38409-H41 | 310 | 1 450 |
| Size film elongation (%) | ASTM D882 | 180 | 52 |
| Shed humidity window (% RH) | In-line hygrometer | 55–75 | 68–78 |
| Regulation/Standard | Scope | Relevant clause / condition |
|---|---|---|
| FDA 21 CFR 176.170 | Components of paper and paperboard in contact with aqueous and fatty food | Table I – conditions of use A through H |
| EU 10/2011 | Plastic materials and articles intended to come into contact with food | Annex I, Table 1 – substance-specific migration limit may apply |
| BfR Recommendation XXXVI | Paper and board for food contact | Pure PVOH meets the positive list for surface-sizing agents |
| Oeko-Tex Standard 100 | Textile ecology | Product class I (baby articles) |
| ISO 14851 | Ultimate aerobic biodegradability in aqueous medium | ≥90% biodegradation within 56 days |
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Polyvinyl alcohol synthesized via continuous alcoholysis of polyvinyl acetate retains a strong affinity for atmospheric moisture. For PVOH 990E—a fully hydrolysed homopolymer with a degree of hydrolysis exceeding 99 mol% and a 4% aqueous solution viscosity positioned within the high-molecular-weight segment—residual moisture content directly governs processing stability. Karl Fischer titration per ASTM D6869-03 routinely reveals as-received moisture levels between 2.5 wt% and 4.0 wt%, depending on ambient humidity during packaging. Introduction of such moisture into a compounding extruder triggers a cascade of thermally induced side reactions that compromise not only the finished film aesthetics but also the polymer backbone integrity.
The primary failure mechanism observed on production-scale twin-screw lines is steam flash in the first compression zone. When pelletized feedstock carrying >0.15 wt% moisture enters barrel zone 2, the temperature plateau of 190–205 °C superheats the water beyond its boiling point, generating internal voids. These voids collapse irregularly at the die land, producing longitudinal die lines and micro-gels visible under 20× magnification on cast film. Beyond surface defects, hydrolysis of residual acetate groups accelerates at elevated temperature in the presence of water, releasing acetic acid that corrodes downstream vacuum calibration sleeves and promotes transesterification when glycerol-based plasticizers are used. To arrest this degradation trajectory, a closed-loop dehumidifying hopper dryer with a molecular sieve desiccant bed is applied. The process air dew point is maintained at or below −40 °C, with an air flow rate of 2.0 m³/h per kg/h of throughput. Under these conditions, pellet moisture falls to <0.12 wt% within 3.5 hours at a resin temperature not exceeding 85 °C, as verified by an inline NIR moisture sensor calibrated against the Karl Fischer method. Failure to achieve this dryness before entering the feed throat typically results in erratic barrel pressure swings of ±15 bar and demands a screw-pull to clear carbonized deposits from the kneading blocks.
Fully hydrolysed polyvinyl alcohol grades in the 990E viscosity class exhibit a narrow thermal processing window that demands precise barrel zoning and low-residence-time screw geometries. A counter-rotating twin-screw extruder with a 45:1 L/D ratio, segmented screw elements, and vacuum devolatilization at barrel zone 9 is the minimum viable configuration for compounding films intended for water-soluble packaging. Temperature profiling follows a rising gradient: feed zone 160 °C, compression zones 190 °C and 200 °C, metering zone 205 °C, and adapter/die zone held at 195 °C. The melt temperature, measured by an immersion-type thermocouple just downstream of the screen pack, must not exceed 215 °C. Exceedance by as little as 5 °C accelerates thermal crosslinking via ether bridge formation between adjacent hydroxyl groups, manifesting as a step increase in melt pressure and a shift in the melt’s dynamic storage modulus G' beyond the linear viscoelastic limit.
Capillary rheometry following ASTM D3835 on formulations containing 12–15 phr glycerol plasticizer yields apparent melt viscosities of 600–800 Pa·s at a shear rate of 100 s⁻¹ and 200 °C, enabling a melt flow index (MFI) suitable for slot die casting of 25–70 µm gauge films. The compounding step must incorporate the plasticizer through a liquid injection port at barrel zone 5, after the primary melting section, to avoid lubricant slip on the pellets and severe surging. Lubricant selection requires caution: calcium stearate at addition levels above 0.5 phr induces stick-slip at the screw tip and periodic melt fracture at the die lip, visible as chevron patterns in the machine direction. Trials on a 60 mm diameter extruder with a 750 mm wide coat-hanger die demonstrated that reducing stearate content to 0.2 phr eliminated the defect while still providing adequate release from the chill roll.
Without a heading, the following paragraph anchors film property differentiation to standardized mechanical testing:When cast onto a chill roll held at 30 °C and subsequently oriented at a draw ratio of 3.5:1, films based on fully hydrolysed PVOH 990E develop a machine-direction tensile strength that, according to published data for this hydrolysis class, registers above 50 MPa at 23 °C and 50 % RH when tested per ISO 527-3 at a crosshead speed of 250 mm/min. Elongation at break, however, typically falls within the 150–200 % range, markedly lower than the 250–350 % elongation observed for 88 mol% hydrolysed copolymers. This reduced extensibility imposes tighter web tension control during secondary converting—dancer roller oscillation amplitude must be kept below ±2 mm to avoid thickness bands that compromise heat-seal integrity in unit-dose detergent sachets. Oxygen permeability, measured at 0 % RH by ASTM D3985, lies in the range 0.2–0.4 cm³·mm/m²·day·atm, and water vapour transmission rate at 38 °C and 90 % RH per ASTM E96 (desiccant method) approaches 800–1200 g·mm/m²·day, demonstrating the high barrier function under dry conditions alongside moisture sensitivity that must be managed during film storage.
The shift from partially hydrolysed polyvinyl alcohol to a fully hydrolysed grade such as 990E in water-soluble packaging for liquid laundry detergents is driven by improved chemical resistance to alkaline formulations and non-ionic surfactants. Immersion testing conducted per ASTM D471 with a model detergent at pH 9.5 and 40 °C reveals that film swelling in the through-thickness direction is limited to less than 5 % after 24 hours for fully hydrolysed grades, compared to 15–20 % for 88 % hydrolysed films. This dimensional stability preserves the burst strength of the unit-dose sachet during warehouse aging, where standard partially hydrolysed films can suffer from creep rupture at corner seals under stack loading of 15 kg. Dart impact resistance, assessed by ASTM D1709 Method A, remains at ≥300 g for a 38 µm film thickness even after 8 weeks of ambient temperature conditioning in contact with the packaged detergent.
Nevertheless, the higher closed-loop crystallinity of PVOH 990E raises the dissolution temperature threshold. Published data for fully hydrolysed high-viscosity polyvinyl alcohol films indicate that complete dissolution in water at 20 °C does not occur within 30 minutes; dissolution initiates above 60 °C and progresses to full solubility at 85–95 °C under gentle agitation. Consequently, the grade is suited for hot-water release applications—such as institutional laundry sachets dosed into wash cycles above 65 °C—and is unsuitable for cold-water home laundry products demanding disintegration below 30 °C. This temperature-dependent solubility profile is a primary differentiator from lower-hydrolysis analogues often specified for cold-water solubility.
On high-speed cast film lines producing 30–50 µm gauge, PVOH 990E generates characteristic defect patterns linked to its high elastic modulus in the melt state. Edge bead formation, amplified by the polymer’s limited melt elongation, requires a vacuum knife positioned 8–12 mm downstream of the die exit and adjusted to a negative pressure of −0.2 bar to pin the web to the chill roll. Without sufficient pinning, the web lifts and develops transverse ripple marks with an amplitude of 2–3 µm that act as stress concentrators during slitting. Release from the polished chromed chill roll depends on the roll surface temperature: at 28–30 °C, auto-release is achieved for plasticized films containing 14 phr glycerol, whereas temperatures below 25 °C result in adhesion requiring an air knife at 1.0 bar. When glycerol content is reduced below 12 phr to raise glass transition temperature for hot-fill applications, the film adheres aggressively to metal surfaces and necessitates a permanent polytetrafluoroethylene sleeve on the peeling idler roll.
Published data for this specific processing configuration is limited, but production logs from 3-layer A/B/A film lines indicate that centre-layer incorporation of 5 wt% plasticized starch improves web release without degrading interlayer adhesion measured by a T-peel test at 200 mm/min (≥8 N/15 mm). The starch acts as a shear-softened internal lubricant, visibly reducing die drool accumulation and extending continuous run time between die-lip cleaning cycles from 6 hours to 12 hours.
| Property | Test Method | Fully Hydrolysed (98–99 mol%) | Partially Hydrolysed (87–89 mol%) |
|---|---|---|---|
| Viscosity (4% aq., 20°C) | ISO 1209 | 70–110 mPa·s | 20–30 mPa·s |
| Tensile strength at break (MD, 23°C/50% RH) | ISO 527-3 | 50–70 MPa | 35–50 MPa |
| Elongation at break (MD) | ISO 527-3 | 150–200% | 250–350% |
| Oxygen permeability (0% RH) | ASTM D3985 | 0.2–0.4 cm³·mm/m²·day·atm | 1.5–3.0 cm³·mm/m²·day·atm |
| Water vapour transmission rate (38°C/90% RH) | ASTM E96 (desiccant) | 800–1200 g·mm/m²·day | 400–600 g·mm/m²·day |
| Dissolution temperature (complete solubility) | Internal visual method | 85–95°C | 20–40°C |
Batch-to-batch consistency of PVOH 990E is further characterised by loss on drying (ISO 1269), ash content (ISO 1407), and bulk density (ISO 1209), values of which are listed on the product’s certificate of analysis and fall within narrow windows that permit automated gravimetric feeding with a deviation below ±0.2% of target mass flow. These metrics, combined with a particle size distribution where ≥98% passes a 1.4 mm mesh, minimise bridging in silo hoppers during continuous compounding operations.
| Standard/Regulation | Scope | Relevant Clause |
|---|---|---|
| FDA 21 CFR 176.170 | Components of paper and paperboard in contact with aqueous and fatty foods | Indirect food additive; limited to specified extractives |
| FDA 21 CFR 175.105 | Adhesives for food contact packaging | Polyvinyl alcohol as component permitted |
| EU Regulation 10/2011 | Plastic materials and articles intended to come into contact with food | Polyvinyl alcohol (FCM substance No. 485) with specific migration limit for vinyl acetate |
| REACH Regulation (EC) 1907/2006 | Registration, Evaluation, Authorisation of Chemicals | Pre-registered polymer; SVHC screening negative |
| RoHS Directive 2011/65/EU | Restriction of hazardous substances in electrical and electronic equipment | Compliant; no restricted heavy metals or flame retardants |
Storage of PVOH 990E shall be within sealed, moisture-barrier bags at warehouse conditions not exceeding 25 °C and 60% RH. Shelf life from the date of manufacture is specified at 12 months when original packaging integrity is maintained; after opening, the material must be consumed within 72 hours or transferred to a dehumidified storage cabinet with a desiccant wheel maintaining an internal dew point below −20 °C. Exposure to ammonia-releasing compounds or volatile amines must be absolutely avoided, as amine-catalysed hydrolysis of residual acetate groups depresses the solution viscosity and broadens the molecular weight distribution to a polydispersity index exceeding 3.5, rendering the grade unsuitable for thin-gauge film extrusion.
