| HS Code | 299488 |
| Product Name | Ningxia Dadi-High Tenacity High Modulus PVA Fiber (HSHM PVA Fiber) |
| Material | Polyvinyl alcohol (PVA) |
| Tenacity | ≥ 13 cN/dtex |
| Initial Modulus | ≥ 350 cN/dtex |
| Breaking Elongation | ≤ 7% |
| Density | 1.30 g/cm³ |
| Fiber Diameter | 10–15 μm |
| Cut Length | 3 mm, 6 mm, 12 mm, 18 mm, 24 mm |
| Melting Point | Approximately 230°C (decomposition range) |
| Moisture Absorption | ≤ 5% |
| Alkali Resistance | Excellent; stable in high-pH cementitious environments |
| Acid Resistance | Excellent; resistant to dilute acids |
| Uv Weather Resistance | Excellent |
| Abrasion Resistance | Very high |
As an accredited Ningxia Dadi-High Tenacity High Modulus PVA Fiber（HSHM PVA Fiber） factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in 25 kg moisture-proof woven bags, palletized and stretch-wrapped, ensuring safe transport and storage of HSHM PVA Fiber. |
| Container Loading (20′ FCL) | 20′ FCL shipment of Ningxia Dadi HSHM PVA fiber, packed in sealed woven bags, palletized and secured for safe transport. |
| Shipping | Shipment of Ningxia Dadi HSHM PVA Fiber requires moisture-proof, export-grade packaging, typically in woven bags or bales on pallets. Ensure containers are clean and dry, with secure lashing to prevent shifting. Store away from heat, sparks, and direct sunlight. Handled as non-hazardous cargo, but standard safe lifting and protective equipment are recommended. |
| Storage | Store in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and open flames. Keep original packaging sealed to prevent moisture absorption. Avoid contact with strong oxidizers and acidic/alkaline chemicals. Maintain moderate humidity and stable temperature. Handle carefully to prevent mechanical damage. Follow local fire and safety regulations for combustible fiber storage. |
| Shelf Life | Shelf life is typically 2 years when stored in a dry, cool, ventilated area away from moisture and sunlight. |
In engineered cementitious composites (ECC) produced for seismic coupling beams and bridge deck link slabs, Ningxia Dadi HSHM PVA fiber is dosed at 1.5–2.0 vol% of total composite volume, equivalent to approximately 19.5–26.0 kg/m³ when calculated against a fibre density of 1.30 g/cm³. The dosage is specified as a volume fraction under ASTM C1116/C1116M-23 Type III synthetic fibre-reinforced concrete and EN 14889-2:2006, with flexural response verified according to ASTM C1609/C1609M-19 or EN 14651:2005+A1:2007. On a production twin-shaft compulsory mixer, the fibre is not discharged as a dry first addition; cement, fly ash, silica fume when specified, and fine aggregate are premixed for 60–90 s, water and polycarboxylate ether superplasticiser are added to form a paste, and the HSHM PVA fibre is then metered through a vibration feeder at a controlled rate so that the fibre is wetted immediately after entering the bowl. Dry fibre added before the saturation phase creates fibre balls at the shaft ends and mid-bowl, and the resulting hardened composite may show low equivalent flexural strength in beam tests even when cylinder compressive strength remains within specification. At 2.0 vol% addition, the plastic viscosity of the mortar phase rises by 1–2 orders of magnitude compared with the same mix without fibre, which is beneficial for segregation resistance but requires rate-of-rise control in vertical formwork. The fibre surface is hydrophilic and absorbs mix water; at 65% RH, the fibre moisture regain is typically 4.5–5.5%, and sacks exposed to relative humidity above 85% should be consumed within 24 h or pre-dried to avoid metering drift in the weigh hopper. Terminal product types include tunnel segment repair overlays, seismic coupling beams for high-rise buildings, monolithic bridge deck link slabs, and blast-mitigation panels in which multiple microcracking is required before strain localisation. The operational boundary is that ambient temperatures above 30°C accelerate slump loss by 30–50 mm within 45 min unless the superplasticiser dosage is adjusted for fibre water demand; field records from precast plants show batch-to-batch differences in agglomerate count more closely track fibre storage humidity than mixer speed.
Hatschek-process fiber cement lines using HSHM PVA fiber as partial asbestos replacement operate under a retention regime that differs sharply from cellulose-only furnishes. The fibre is added to the cement-silica-cellulose slurry at 1.0–2.5% of dry furnish mass, with 6 mm cut length used on multi-vat Hatschek machines and 12 mm cut length on air-cured spray-up lines where dimensional stability class is lower. The governing product standards are ISO 8336:2017 for flat fibre-cement sheets, EN 12467:2012+A2:2018 for sheets and fittings, EN 494:2012+A1:2015 for profiled sheeting, and ASTM C1186-22 for flat sheets; fire resistance is tested under EN 13501-1 and ISO 1182 for non-combustibility component testing. The production process on a Hatschek machine begins with slushed unbleached Kraft cellulose refined to 25–45°SR, blended with Portland cement, silica flour, and HSHM PVA fibre in continuous mixing chests; rotating sieve cylinders deposit monolayer films onto an accumulation felt, and the built-up green sheet is compressed through vacuum dehydration and press rolls before autoclaving at saturated steam pressures of 0.8–1.2 MPa and temperatures of 170–190°C for 8–12 h. The process restraint is that high levels of PVA fibre slow dewatering on the felt because the hydrophilic fibre retains water in the deposited film; line speed reductions of 5–15% are typical when moving from 1.0% to 2.5% fibre addition unless vacuum box configuration is upgraded. Terminal product types include corrugated roofing sheets, flat interior wallboard, ventilated facade panels, and fire-protection board for steel-frame buildings where non-asbestos fibre reinforcement must deliver both wet green-sheet handling strength and autoclaved flexural modulus. The incompatibility boundary is that highly refined cellulose above 45°SR combined with top-end PVA fibre addition can generate a dense floc network in the mixing chest and uneven sheet formation, so furnish refining and cationic retention aid dosage must be co-optimised when the PVA content exceeds 2.0%.
For high-efficiency fuel-air separation media and HVAC bag filters formed on inclined-wire wet-laying machines, HSHM PVA fibre is incorporated at 5–20 wt% of dry furnish, with the lower end 5–8 wt% used to stabilise pleats in cellulose/glass hybrids and the upper end 15–20 wt% reserved for synthetic bicomponent-free formulations where PVA acts as both load-bearing fibril and sacrificial binder. The product must satisfy ISO 9073-2:2023 for thickness, ISO 9073-3:2023 for tensile strength, ISO 12956:2020 for pore size distribution by bubble point, and EN 1822-1:2019 for HEPA filter media classification when the downstream filter element is tested. The production route runs through a pulper, refiner or dispersion tank, headbox, moving wire, vacuum suction boxes, hydroentanglement or light calendering, and through-air or cylinder drying. The process-limiting conflict is between drainage and tensile development: fibrillated HSHM PVA segments increase surface area and lower freeness, so the furnish may drop from 60 °SR to 85 °SR depending on fibre cut length and headbox consistency; wet-end retention aids such as cationic polyacrylamide are then required at 0.05–0.15% of furnish mass to hold fine PVA segments on the wire. Terminal product types include pleated air filtration cartridges, fuel-water coalescer media, automotive cabin filters, and vacuum bag media where burst strength and pleat spring-back after cyclic humidity are the controlling purchase specifications. The operational boundary is that HSHM PVA fibre should not be refined with high-intensity plate refiners because it can wrap around the rotor and create batch-to-batch basis weight variation; low-intensity disc refining is the maximum allowable mechanical treatment.
Continuous filament HSHM PVA in braided marine rope construction requires a different twist balance than polyester or nylon because the fibre’s wet/dry strength differential remains smaller but its creep under sustained load is lower. The load-bearing core is typically built at 70–100 wt% HSHM PVA filament, with the balance being polyester or aramid in hybrid constructions intended to trade wet abrasion resistance against cost or specific energy absorption. The governing standards for general fibre ropes include ISO 9554:2019 and ISO 2307:2021; marine rope performance is additionally specified by Cordage Institute CI 1301-15 for comparative fibre rope use, and for aquaculture netting the mesh strength test follows ISO 1806:2002. The production process starts with high-tenacity PVA filament yarns twisted on ring twisters to balanced plied yarns, followed by braiding on 12- to 48-carrier braiders, hot stretching at 120–150°C under tension to remove latent twist, and optional polyurethane abrasion coating applied at 3–7% dry mass. Terminal product types include mooring tails, trawl and purse seine netting, aquaculture cage ropes, and shipping container security nets. The main incompatibility is concentrated strong acids and prolonged immersion above 60°C in closed recirculation aquaculture systems, which can reduce molecular weight and knot strength faster than PET or PA in the same installation; published field data for this specific HSHM grade in recirculating aquaculture water is limited.
For woven geotextile fabrics made from high-tenacity PVA slit-film or multifilament yarns, the addition in the warp direction is specified as 100% HSHM PVA in load-bearing ribs, while weft insertion may use a 50/50 PVA–polypropylene hybrid to lower stretch and retain hydraulic opening size. The governing compliance framework is ISO 10318:2023 for geosynthetic definitions and functions; tensile testing follows ASTM D4595-17 or ISO 10319:2015, puncture resistance follows ISO 12236:2006, and installation damage is assessed under ISO 13437:2019. The production process involves warp knitting or shuttle weaving on heavy rapier looms, followed by a hot air relaxation stage at 100–120°C to stabilise crimp, and then fabricated seams by stitching or welding when the PVA yarn is pre-treated with a low-melt copolyester tie layer. Terminal product types include coastal erosion control mattresses, temporary haul road separation fabrics, landfill drainage geocomposites, and alkaline mine-site liner protection layers. The operational limitation is that PVA fibre absorbs water and can exhibit short-term thickness swell at 20–30% in saturated fill, which tightens the fabric’s apparent opening size and can reduce in-plane permeability if the geotextile is designed too close to the minimum filtration opening size; long-term alkaline hydrolysis resistance is better than polyester when exposed to calcium-rich pore water above pH 11, but published data for this specific high-modulus grade in landfill leachate of pH 12.5 is limited.
Short-fibre-reinforced SBR, NBR, and EPDM compounds used for tension-member encapsulation and hose carcass layers accept HSHM PVA fibre at 8–20 phr on the rubber hydrocarbon content, with 12–15 phr representing the most common window for V-belt base compounds that require transverse stiffness without complete loss of elongation at break. The governing test methods are ISO 37:2017 for vulcanised rubber tensile stress-strain, ISO 34-1:2022 for trouser and angle tear, ISO 48-4:2018 for durometer hardness, and ASTM D5992-14 for dynamic compression testing of rubber compounds. The production route uses an internal mixer with intermeshing rotors at a fill factor of 0.70–0.80, with PVA fibre added after carbon black or silica is incorporated but before curatives; the batch is dropped at 140–155°C, sheeted on a two-roll mill at 40–60°C to orient short fibres in the machine direction, and then calendered or extruded into rubber sheets before vulcanisation at 150–170°C. The process bottleneck is fibre breakage and anisotropic shrinkage: at charge levels above 20 phr, the compound becomes boardy and calendering nip feeding becomes unstable, while fibre orientation can produce tensile strength in the machine direction that is 2–3 times the transverse direction value. Terminal product types include automotive V-belts, synchronous belts, high-pressure hydraulic hose covers, conveyor belt edge strips, and rubber crawler track reinforcement strips. The limitation is that HSHM PVA fibre should not be used in compounds requiring acid-cure systems with strong mineral acid accelerators unless the fibre is pre-coated; published data for this specific high-modulus fibre in acid-cured EPDM compounds is limited.
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Designated as Ningxia Dadi-High Tenacity High Modulus PVA Fiber（HSHM PVA Fiber）, the product is a wet-spun polyvinyl alcohol staple fiber manufactured from high-molecular-weight PVA resin. The production route combines aqueous dope coagulation, multi-stage tensile drawing, and thermal stabilization under tension; this sequence raises specific tenacity and initial modulus beyond ordinary PVA staple. The fiber is supplied as chopped monofilament, with cut lengths reported in producer literature at 4 mm, 6 mm, 8 mm, and 12 mm, and with linear density concentrated near 2.0 dtex. Lot certificates generally include fiber diameter, linear-density deviation, tenacity, elongation at break, hot-water shrinkage, and moisture content.
| Property | Typical value or range | Test basis |
|---|---|---|
| Linear density | 1.5–2.2 dtex | ISO 1973:2021 / gravimetric |
| Tenacity | 12.5–15.5 cN/dtex | ISO 5079:2020 |
| Tensile modulus | 280–340 cN/dtex | ISO 5079:2020 initial slope |
| Elongation at break | 6.0–8.5% | ISO 5079:2020 |
| Density | 1.29–1.31 g/cm³ | ISO 1183-1:2019 or pycnometry |
| Hot-water shrinkage | ≤ 2.0% at 95°C / 30 min | Producer method |
| Moisture content at dispatch | ≤ 1.0 wt% | Producer method |
The table values are lot-averaged ranges, not guaranteed minima for a specific production batch. The spin finish applied to the cut fiber influences dispersion in cement paste; removal of the finish by prolonged pre-wetting or aggressive alkali handling changes the yield-stress response and should be avoided unless the process specifically requires it.
The principal performance difference lies in fiber axial stiffness and interfacial shear capacity in a high-pH cement matrix. HSHM PVA Fiber is specified with a tenacity above 12 cN/dtex and an initial modulus commonly above 280 cN/dtex. A general-purpose wet-spun PVA staple typically occupies a lower tenacity band. In early-age microcracks narrower than 50 µm, crack-bridging stress is governed by fiber modulus, fiber orientation, and the chemical bond between the PVA surface and hydrating paste. The hydroxyl functional group on the PVA surface provides matrix interaction that hydrophobic polypropylene fiber lacks; polypropylene microfibre also fails to produce a continuous post-crack response at equivalent aspect ratio because its modulus is in the range of 3.5–7 GPa. However, the same hydrophilic surface causes HSHM PVA Fiber to bind more batch water and increases plastic viscosity more rapidly than polypropylene at volume fractions above 1.5 vol%.
Flexural comparison should be verified by EN 14651 notched beam tests or ASTM C1609/C1609M-19a third-point beam tests, not by fiber tensile strength alone. The operational parameter is residual stress at crack mouth opening displacement 0.5 mm and 2.5 mm. Substitution for general-purpose PVA is more straightforward than substitution for steel fiber because the material class and aspect ratio are closer. Substitution of polypropylene with HSHM PVA requires review of matrix volume fraction and mixing energy; equal volume addition can produce different slump and air content even when fiber count is similar.
Compared with silane-modified PVA fibers used in some engineered cementitious composite formulations, HSHM PVA Fiber may show a different interfacial frictional bond depending on the spin finish. Some PVA fibers are oil-treated to reduce cementitious bond and increase strain-hardening capacity; the HSHM grade is supplied for general fiber-reinforced concrete and fibre-cement use. Users should not assume the same surface treatment as an ECC-optimized PVA grade without lot-specific data.
Field records from precast plants using a 250 L pan mixer indicate that the full fiber charge should not be introduced into the dry aggregate phase. In one production campaign, direct addition to dry powder at less than 30 rpm produced persistent fiber balls that were retained on a 75 µm sieve; a staged feed over 45 seconds after water and polycarboxylate ether were mixed eliminated the defect. At 2.0 vol% fiber loading, the fresh mortar showed a slump-flow reduction of approximately 100–180 mm and could be restored with a viscosity-modifying agent without additional water. This is typical for hydrophilic PVA fiber in low water-to-binder mixtures. Mixing time required for complete fiber opening is shorter with 6 mm fiber than with 12 mm fiber, but the longer fiber provides higher residual stress in larger sections.
Replacement of hooked-end steel fiber with HSHM PVA Fiber is limited by modulus and anchorage mechanics. Steel fiber has a Young’s modulus near 200 GPa; HSHM PVA Fiber lies near 30–40 GPa. For a cracked thin section at crack width above 0.2 mm, a steel fiber may still carry substantial load through mechanical anchorage, while a synthetic PVA fiber of 12 mm length will begin to pull out or rupture depending on bond strength. For this reason, HSHM PVA Fiber is specified in thin architectural cladding, permanent formwork, and non-structural precast where service crack width is controlled by reinforcement or where early-age shrinkage control is the primary objective. The material can also be used in hybrid systems with steel fiber to improve crack distribution without fully replacing steel. Published data for this specific HSHM grade in structural beams under EN 14651 are limited; project-specific validation of residual flexural strength at CMOD 0.5 mm and 2.5 mm is required.
| Fiber class | Density (g/cm³) | Tensile strength (MPa) | Tensile modulus (GPa) | Typical diameter (mm) | Alkali behaviour |
|---|---|---|---|---|---|
| HSHM PVA | 1.29–1.31 | 1,200–1,600 | 30–40 | 0.04–0.20 | Stable in cement paste; retains wet strength |
| General-purpose PVA | 1.28–1.30 | 700–1,000 | 15–25 | 0.04–0.20 | Stable |
| Polypropylene | 0.90–0.92 | 300–500 | 3.5–7 | 0.02–0.05 | Stable but hydrophobic |
| AR-glass | 2.68 | 1,700–3,500 | 72 | 0.01–0.02 | Requires zirconium dioxide; otherwise silica dissolution |
| Hooked-end steel | 7.85 | 1,100–2,100 | 200 | 0.5–1.0 | Corrosion risk if cracking reaches surface |
These comparative values are material-class ranges from published polymer and fiber literature, not producer-guaranteed values for a specific batch. The key substitution decision is therefore not density or tensile strength in isolation, but residual post-crack stress measured in the target matrix. HSHM PVA offers the greatest advantage when the section is thin, corrosion-free service is desired, and crack widths are kept below approximately 0.1 mm.
Mixing equipment type alters the loading sequence. In twin-shaft paddle mixers, fiber is often added after initial wetting of coarse and fine aggregate but before full addition of cementitious fines, which allows mechanical opening of agglomerates. In high-shear pan mixers, the fiber is generally charged last to reduce filament breakage from long residence time. Static charging in dry air below 30% relative humidity causes wall adhesion and feed-throat buildup; plant records recommend maintaining the batching area at 40–60% relative humidity and checking fiber moisture content. Pre-wetted fiber may not feed uniformly through vibratory metering equipment and can form lumps at the feed throat. At loadings above 2.0 vol%, the mix can shift from flowable to extrudable; rheometer data on similar hydrophilic PVA fibers show a marked increase in yield stress when fiber–matrix contact networks form. Batch operators should avoid adding excess water to reduce viscosity because it lowers the fiber–matrix interface strength and increases pore size.
Incoming inspection at a precast plant should include fiber length distribution, moisture content, and standardized mortar dispersion. For length distribution, a 200-fiber count under an optical microscope detects excess short fibers or double-length fibers. Moisture content is determined by oven drying at 105°C to constant mass; deviation above 1.0 wt% suggests damaged packaging and can cause feeding problems. Dispersion screening can be performed by adding fiber at 2.0 vol% to a reference mortar and passing the fresh mix through a 75 µm sieve; retained fiber balls above 0.5 wt% of total fiber mass indicate a finish or mixing issue. These are operational controls drawn from fiber-reinforced concrete quality programs, not standard acceptance criteria.
The product falls under synthetic fiber classification in ASTM C1116/C1116M Type III for fiber-reinforced concrete, provided the aspect ratio and tensile property requirements are met. For compliance documentation, the producer can supply a mill certificate with ISO 9001 lot traceability; certificate content varies by shipment and should be checked against the project specification before batching.
In Hatschek fibre cement sheet production, HSHM PVA Fiber is introduced as a partial replacement for refined cellulose pulp or as a supplemental fiber in autoclaved calcium silicate boards. 4 mm to 6 mm fibers are preferred; 12 mm fiber can block the sieve cylinder and slow drainage. The accepted dosage is usually below 1.5 wt% of dry solids in the slurry. Mill trials show that exceeding this level increases backwater consistency and may require supplementary flocculant and lower machine speed. Autoclaving at 180°C or below is generally tolerated for PVA fiber during the standard cycle; published data for the specific HSHM grade under prolonged steam cycles remain limited to producer test reports.
Operational boundaries include strong oxidizing acid environments and melt-compounding temperatures above 220°C, at which PVA degrades. In non-aqueous polymer matrices, the hydrophilic fiber surface can yield low interfacial shear strength without coupling-agent treatment. The product should not be combined with cationic flocculants that invert the spin finish charge unless a site-specific compatibility trial is performed. In cementitious systems with polycarboxylate ether superplasticizers, some PVA fiber finishes show delayed fiber dispersion; a contact-time test in the actual mixer is more reliable than a beaker test. Published data for HSHM PVA in amine-containing coatings or solventborne resin systems are limited; those applications require surface-treatment development and bonding verification.
