| HS Code | 163930 |
| Fiber Type | PVA (Polyvinyl Alcohol) High Tenacity High Modulus |
| Dry Tenacity | ≥ 14 cN/dtex |
| Dry Initial Modulus | ≥ 300 cN/dtex |
| Elongation At Break | 4 – 8% |
| Density | 1.30 g/cm³ |
| Melting Point | 220 – 230°C |
| Fiber Diameter | 10 – 15 μm |
| Staple Cut Length | 3 – 20 mm (customizable) |
| Alkali Resistance | Strength retention ≥ 97% in 10% NaOH at 80°C for 2 h |
| Acid Resistance | Strength retention ≥ 95% in 10% HCl at room temperature for 1 h |
| Moisture Regain | ≤ 5% |
| Color | Pale yellow or white |
| Heat Resistance | Stable under dry heat up to ~150°C |
| Dispersibility In Water | Easily dispersed without gelation |
| Abrasion Resistance | Excellent |
As an accredited Shuangxin SX-1-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 woven bags with inner plastic lining, palletized and shrink-wrapped for dry, safe transport and storage. |
| Container Loading (20′ FCL) | 20′ FCL container loading: HSHM PVA Fiber packed in pressed bales or cartons, secured palletized for efficient, safe transport. |
| Shipping | Shuangxin SX-1 HSHM PVA Fiber is shipped in dry, moisture-proof bales or cartons with protective lining. Store away from direct sunlight and humidity. Ensure secure palletization during transit to prevent damage. This non-hazardous material requires standard dry cargo handling, avoiding excessive compression and exposure to water. |
| Storage | Store Shuangxin SX-1 HSHM PVA Fiber in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and open flames. Keep packages tightly sealed and protected from moisture and mechanical damage. Avoid contact with strong oxidizers. Maintain proper stacking order, with a stable climate and pest-free environment to preserve product performance. |
| Shelf Life | Shelf life is typically two years when stored unopened in a cool, dry, well-ventilated area. |
In thin-section cementitious repair overlays, the transition from a single-crack brittle failure to multiple fine cracking is controlled by fibre stiffness, matrix fracture energy, and fibre–matrix bond. The Shuangxin SX-1 high-tenacity high-modulus PVA fibre is specified in such systems at dosage levels between 1.50 vol% and 2.50 vol%, with a nominal cut length of 8 mm or 12 mm selected according to aggregate packing and overlay thickness. The fibre class typically exhibits a tensile tenacity above 13 cN/dtex, an initial modulus above 300 cN/dtex, density near 1.29 g/cm³, and elongation at break in the 6.0–8.0% range, as stated in manufacturer product data. When dispersed in a mortar containing CEM I 42.5 N, 8 wt% silica fume, and a water–binder ratio near 0.25, the fibre modifies the post-cracking response measured under ASTM C1609/C1609M-19a and EN 14651:2005+A1:2007. The end product is typically a strain-hardening cementitious composite used in bridge deck link slabs, building facade repair, and precast shell elements.
The mixing sequence in a 50 L planetary mixer conforming to EN 196-1:2016 is the principal determinant of fibre dispersion. Dry blending of the SX-1 fibre with cement and silica fume before water addition is inferior to delayed addition after a fluid paste has formed. A controlled addition of fibre at low agitator speed over 60–90 s reduces fibre balling and air entrapment. Polycarboxylate ether superplasticizer is adjusted to maintain a slump flow compatible with formwork geometry without exceeding an air content of 3.0% by volume. Batch-to-batch variation in fibre cut length and moisture regain is a documented source of scatter in ASTM C1609/C1609M-19a residual strength; incoming lots should be tested for cut length distribution using a fibre length analyser and for moisture regain before batching.
The first-crack strength is not increased by fibre addition in the same proportion as matrix strength; rather, the fibre alters the ratio of residual flexural strength to first-crack strength. Design verification therefore requires notched beam testing under EN 14651:2005+A1:2007 and reporting of the limit of proportionality and residual flexural tensile strength at crack mouth opening displacement values of 0.5 mm, 1.5 mm, 2.5 mm, and 3.5 mm. When the HSHM PVA fibre is used in cementitious composites with a matrix fracture energy above the fibre bridging stress capacity, crack widening is arrested and multiple microcracking occurs. Single-fibre pullout tests on an electrodynamic tensile tester with a 10 N load cell are used to quantify the fibre–matrix interfacial shear strength and slip-hardening response that control this microcracking behaviour. At relative humidity above 60%, fibre bales should be conditioned in a dry room and, if necessary, pre-dried at 40 °C for 4 h before weighing to avoid false dosage caused by moisture regain.
| Application | Test method designation | Measured parameter |
|---|---|---|
| Fibre-reinforced mortar flexural toughness | ASTM C1609/C1609M-19a | Residual flexural strength ratio f300/f150 |
| Notched beam flexural toughness | EN 14651:2005+A1:2007 | Limit of proportionality, residual flexural tensile strength |
| Sprayed concrete energy absorption | ASTM C1550-12a | Energy absorption to 40 mm central deflection |
| Fibre-cement flat sheets | ISO 8336:2017 | Modulus of rupture, saturated and dry |
In underground TBM tunnel support, synthetic macro fibres are exposed to high-speed spray impact, alkaline accelerator chemistry, and early-age load from geological relaxation. The Shuangxin SX-1 HSHM PVA fibre is employed in wet-mix sprayed concrete at addition rates commonly bracketed between 4.0 kg/m³ and 8.0 kg/m³, with the final dosage validated by round panel testing to ASTM C1550-12a and energy absorption classification under EN 14487-1:2005. In a wet-mix sprayed concrete machine equipped with a positive-displacement pump and nozzle-mounted alkali-free aluminium sulfate accelerator, the HSHM PVA fibre enters the mix in the agitator stream after the aggregate and cement have been blended at the batching plant. The most frequent processing bottleneck is fibre clumping at the pump hopper when fibre is added too rapidly or when the aggregate moisture content exceeds 1.0% by mass. Accelerator dosage is commonly adjusted between 4% and 8% by cement mass, with setting time verified under EN 196-3:2016 at the site batch plant.
Because HSHM PVA fibre has a density near 1.29 g/cm³, its rebound loss during spraying is generally lower than steel fibre of comparable aspect ratio, but the comparison is strongly influenced by air velocity at the nozzle, accelerator type, and spray operator technique. Quantitative rebound comparisons require site-specific calibration with a standard rebound box. The hardened shotcrete should be tested for energy absorption under EN 14488-3:2006 or ASTM C1550-12a; the choice between these methods changes the reported energy absorption values and cannot be interchanged for specification compliance. Target energy absorption class E500 or E700 is frequently specified for permanent rock support, but excavation-specific ground class definitions under EN 14487-1:2005 should govern the exact value.
Alkaline durability is the primary long-term concern in saturated calcium hydroxide environments. The fibre should be evaluated by immersion in saturated Ca(OH)2 at 60 °C for 90 days, followed by tensile testing according to ISO 2062:2009 or equivalent, to confirm retained tenacity exceeds 90% of the as-received value. Published data for this specific SX-1 configuration in permanent shotcrete is limited, so qualification testing on production-mix panels is required. The addition of HSHM PVA fibre does not replace crack control measures at rock contour changes, and severe water inflows reduce pumpability and fibre distribution uniformity.
For woven and needle-punched geotextiles in coastal erosion control, the reinforcement yarn must combine high modulus with wet strength retention and low elongation under sustained soil load. The Shuangxin SX-1 HSHM PVA fibre is processed into staple yarns and nonwoven fabrics where the required wide-width tensile strength is verified under ISO 10319:2015 and static puncture resistance under ISO 12236:2006. The apparent opening size of a woven geotextile is measured under ISO 12956:2020; a low apparent opening size is necessary to contain fine silty soils, but over-tight fabrics can create uplift pressure beneath wave-loaded revetments. The design balance between soil retention and permeability is evaluated by combining ISO 12956:2020 with water permeability characteristics determined under ISO 11058:2019.
In a weaving plant, high-modulus PVA yarns are processed on a Dornier rapier loom with a weaving width of 430 cm; yarn tension is controlled below 2.0 cN/dtex to limit strength loss at the reed. The finished fabric is heat-set at 120–140 °C for dimensional stability under wave impact. The high modulus of HSHM PVA fibre reduces elongation under wide-width load, which is an advantage in basal reinforcement of embankments on soft clay. However, the low elongation also means that geotextile puncture and tear propagation resistance must be confirmed under ISO 13433:2006. Ultraviolet exposure is a known operational boundary; unprotected PVA yarns should be specified only where the fabric is permanently covered by sand, rock, or concrete. For exposed installation periods, UV resistance is assessed under ASTM D4355/D4355M-18, and carbon black or UV-stabilised coating is recommended.
With three-strand laid and twelve-strand braided constructions, HSHM PVA fibre is used in winch lines, aquaculture net cages, and offshore mooring assist lines where low creep under sustained load is a selection driver relative to high-tenacity polyester or nylon. The breaking load of the finished rope is determined under ISO 2307:2019, while yarn strength conversion efficiency in a three-strand laid rope is typically between 75% and 85% depending on twist factor and lubrication. The SX-1 grade is introduced as a high-modulus component in blended constructions to reduce elongation and improve sheave wear resistance. The wet strength retention of PVA fibre is often reported above 80% of oven-dry tenacity, but the exact retention for SX-1 in marine rope construction should be confirmed by immersion testing under ISO 2307:2019 after 24 h water conditioning.
A significant process constraint is the twist setting and bending fatigue of PVA yarns. PVA fibres are sensitive to sustained bending over small radii; cyclic bending over a pulley with a diameter-to-rope diameter ratio below 20:1 can produce premature internal abrasion. Rope sheaves and rollers should therefore maintain a D/d ratio of at least 20:1, with larger ratios required for high-cycle applications. The high fibre modulus increases rope stiffness, which improves load control but reduces fatigue life if the rope is bent beyond its elastic curvature limit. Published data for this specific SX-1 rope configuration is limited; rope manufacturers qualify new yarns with fatigue testing on a rotating sheave test rig under a specified load cycle, typically 10,000–50,000 cycles at 20% of breaking strength. The final rope construction should also be tested for splice strength retention under ISO 2307:2019 if the application requires splicing rather than hardware termination.
When autoclaved fibre cement sheets are produced on a Hatschek machine, the reinforcement fibre must survive alkaline slurry, vacuum dewatering, and saturated steam curing without brittle failure. The Shuangxin SX-1 HSHM PVA fibre is incorporated into cellulose-based fibre cement at dosages between 1.0 wt% and 2.5 wt% of total dry fibre content, with the exact dosage fixed by modulus of rupture testing under ISO 8336:2017 and design requirements in EN 12467:2012+A1:2016. The fibre is added after cellulose defibration in a hydrapulper to avoid fibre balling in high-turbulence zones. Machine trials show that staged addition of SX-1 fibre after cellulose has been refined to a Schopper-Riegler freeness of 30–40 °SR improves retention on the sieve and reduces fibre loss in white water. The Hatschek machine formation process uses rotating cylindrical sieves, vacuum boxes, and accumulator rolls to build a thin wet sheet that is later pressed and autoclaved.
The autoclave cycle usually operates at 170–180 °C and 0.8–1.0 MPa saturated steam for 8–12 h; under these conditions the cellulose fraction degrades partially, while the PVA fibre must retain sufficient modulus to carry bending loads. Validation of the SX-1 grade therefore includes retention testing in a saturated calcium hydroxide matrix environment with subsequent tensile testing of extracted fibres or flexural testing of composite sheets under ISO 8336:2017. The saturated density of the cured sheet, typically between 1.30 g/cm³ and 1.60 g/cm³, is controlled by press pressure and autoclave duration. The final facade or cladding element is classified under EN 12467:2012+A1:2016 according to bending strength, water tightness, and dimensional stability. A known operational boundary exists at high ambient relative humidity: fibre bales should be pre-conditioned below 60% RH because moisture regain can change fibre feeding rates and reduce sheet basis weight consistency.
In power transmission belts and hose plies, short-cut HSHM PVA fibre is dispersed into rubber compounds to raise low-strain modulus and reduce die swell without the weight and metallic adhesion systems required for steel wire cord. The fibre is cut to 3 mm or 6 mm and added at 10–20 phr in a laboratory internal mixer or production Banbury mixer with a fill factor of 0.70–0.80. The mixing sequence brings the rubber to a dump temperature below 120 °C to avoid pre-scorch when curatives are added. Tensile stress-strain is measured under ISO 37:2017; abrasion resistance is determined under ISO 4649:2017; and cure kinetics are recorded on an oscillating disc rheometer under ISO 3417:2008 with parameters ML, MH, ts2, and t90.
The polar surface of PVA fibre requires adhesion treatment before mixing into a non-polar rubber matrix. Resorcinol-formaldehyde-latex dipping is common for synthetic fibres, but PVA often requires an isocyanate or epoxy pre-dip before RFL to achieve adequate cord adhesion. Short-fibre reinforcement increases low-strain modulus, reduces die swell during extrusion, and improves cut resistance; however, over-addition above 20 phr can reduce elongation at break sharply and raise Mooney viscosity to a level that impairs downstream calendering. The operational boundary for moisture is significant: at relative humidity above 65%, PVA fibre must be pre-dried at 60 °C for 4 h before compound mixing, otherwise moisture release during mixing can produce porosity and cure variation.
In a compression-moulded belt section, the HSHM PVA fibre orientation follows the direction of flow, and anisotropic modulus is measured by cutting test pieces in the machine direction and cross direction under ISO 37:2017. Published data for this specific SX-1 grade in rubber compounds is limited; compounders typically run a design-of-experiments matrix across fibre loading and pre-treatment temperature to establish process windows.
| Parameter | Standard designation | Reported value |
|---|---|---|
| Tensile stress at 100% elongation | ISO 37:2017 | Compound-specific |
| DIN abrasion volume loss | ISO 4649:2017 | Compound-specific |
| Cure time t90 | ISO 3417:2008 | Compound-specific |
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The Shuangxin SX-1-High Tenacity High Modulus PVA Fiber（HSHM PVA Fiber） is a synthetic monofilament reinforcement grade for cementitious matrices, fiber-cement board manufacture, engineered cementitious composites, and short-fiber composite systems. The SX-1-HSHM designation identifies a high-tenacity, high-modulus polyvinyl alcohol fiber in which polymer chain orientation generated during high-draw processing raises the tensile modulus into the crack-bridging range beyond that of textile-grade PVA staple. Unlike water-soluble PVA staple, SX-1-HSHM is a high-crystallinity, high-orientation grade that does not dissolve in cold or warm water; this property is essential for survival during concrete mixing and long-term exposure to cement pore solution. Published data for this specific configuration is limited; the values discussed below are class-typical for high-tenacity high-modulus PVA fiber and should be verified against Shuangxin batch certificates for exact SX-1-HSHM cut-length distribution, filament diameter, surface finish, and mechanical data.
Incoming inspection for SX-1-HSHM should require tensile strength and modulus testing on single filaments under ASTM D3822/D3822M-14 or equivalent ISO 2062:2009 procedures. The values in Table 1 are the industrial envelope for HSHM PVA fiber; the manufacturer certificate may report narrower product-specific ranges.
| Property | Class-typical range | Test method |
|---|---|---|
| Tensile strength at break | 1,200–1,600 MPa | ASTM D3822/D3822M-14 |
| Tensile modulus | 30–43 GPa | ASTM D3822/D3822M-14 |
| Elongation at break | 6–10% | ASTM D3822/D3822M-14 |
| Density | 1.28–1.30 g/cm³ | Density gradient column |
| Nominal diameter | 12–20 µm | Optical microscopy |
| Cut length | 4–12 mm | Sieve or image analysis |
| Moisture regain at 65% RH | 3–5 wt% | Gravimetric conditioning |
| Thermal decomposition onset | 200–230 °C | Thermogravimetric analysis in air |
For specification compliance, SX-1-HSHM may be classified under ASTM C1116/C1116M as a Type III synthetic fiber when incorporated in concrete. Microsynthetic dosage for plastic shrinkage control is commonly 0.6–1.5 kg/m³; macro-synthetic performance evaluation under ASTM C1609/C1609M-19a becomes relevant when fiber length is at least 12 mm and the dosage is above 1.5 kg/m³. Acceptance testing should also record cut-length distribution because variability above ±1 mm alters fiber count per unit volume and post-crack residual strength in thin-section precast elements. In single-filament tensile testing, coefficient of variation for HSHM PVA fiber is commonly 5–12%; a coefficient above 15% indicates poor drawing uniformity or filament damage and can reduce batch performance in strain-hardening mixes.
The hydroxyl-rich backbone of SX-1-HSHM is the primary chemical variable separating it from polypropylene and polyester monofilaments in cementitious service. PVA fibers form hydrogen bonds with cement hydration products, particularly calcium silicate hydrate, producing higher single-fiber pullout resistance than hydrophobic fibers at the same embedded length. General-purpose PVA staple is typically below 900 MPa tensile strength and 10–20 GPa modulus; SX-1-HSHM falls in the 1,200–1,600 MPa and 30–43 GPa ranges. Relative to aramid, SX-1-HSHM has lower stiffness but comparable density and improved alkaline stability without requiring a sacrificial sizing. Relative to AR glass fiber, SX-1-HSHM has a lower modulus but does not rely on zirconia content to resist portland cement pore solution.
For fiber length selection, the critical embedded length can be estimated from the class-typical tensile strength of 1,400 MPa, filament diameter of 14 µm, and interfacial shear strength near 1.5 MPa. The resulting critical length is approximately 6.5 mm; cut lengths shorter than 12 mm may therefore not develop full tensile capacity in smooth-surfaced cementitious matrices. This is why macro-synthetic applications generally specify 12 mm or longer fibers, while microsynthetic plastic shrinkage control can use 4–6 mm fibers where full fiber rupture strength is not the governing design parameter. High-shear mixing above 25 m/s can reduce fiber length distribution through bending fatigue; production trials should include wash-out and image analysis after 90–120 s of mixing to confirm length retention.
Batching sequence in a twin-shaft compulsory mixer with a volume of 1 m³ should avoid adding fiber before coarse aggregate because fiber can wrap around mixer blades and form nests. Fiber is commonly added over 30–60 s at full mixing speed; if bags are emptied into a stationary mixer, dispersion time doubles and localized water-cement ratio variations occur. In truck-mixed concrete, fiber should be added at the batch plant rather than at the site to allow mixing energy control. These production practices are generic to synthetic microfiber use and apply to SX-1-HSHM.
In fiber-cement board manufacture, SX-1-HSHM is dispersed into a dilute water furnish containing cement, ground silica, and cellulose pulp. Typical addition rates are 1.0–3.5 wt% of dry furnish. The fiber is subjected to repeated passes through recirculating white water, formation cylinders, and vacuum dewatering; production-scale difficulties are most often associated with mat formation when fiber is added too rapidly to a low-shear pulper. Local fiber concentration in the pulper should remain below approximately 0.8 wt% of slurry mass, and a high-shear disperser with a tip speed of at least 15 m/s should be used before the suspension enters the mixing vat. Batch-to-batch variation in cut length and crimp directly controls retention on the felt. Fiber fines below 2 mm may pass through the forming wire and accumulate in process water, while excessively long fiber can wrap around screen-sieve shafts and reduce dewatering uniformity.
If the fiber is evaluated for autoclaved fiber-cement production, plant trials should include saturated steam exposure at 170–190 °C and post-autoclave flexural testing, because published data for SX-1-HSHM under autoclave cycles is limited. PVA fiber chemistry generally retains strength better than cellulose pulp under hot alkaline conditions, but sizing and crystallinity influence the result. For air-cured fiber-cement sheets, the main processing holdback is not thermal degradation but poor retention and nonuniform distribution caused by slurry flocculation.
In cast-in-place concrete and precast production, the fiber is typically added after coarse aggregate and part of the mixing water. For plastic shrinkage crack control evaluated under ASTM C1579-21, the dosage range is 0.6–1.5 kg/m³. For engineered cementitious composite mixtures, PVA fiber volumes near 2.0 vol% are common, and direct tensile strain capacities of 3–6% have been reported for suitable matrix chemistries; published data for this specific SX-1-HSHM configuration is limited, so strain-hardening performance must be verified on the actual production mix. At high fiber volumes, the increase in total surface area raises water demand, and a polycarboxylate ether superplasticizer is generally required to maintain a flow-table spread of 150–250 mm under ASTM C230/C230M. Mixing should continue 60–120 s after fiber addition at high shear to prevent fiber balling, followed by shorter low-shear mixing before placement.
For fiber-cement sheet products, specification compliance is generally assessed under ISO 8336 or the relevant national equivalent. Test coupons should be sampled from the full sheet width because fiber orientation in Hatschek machines is not random; the forming direction produces anisotropy in flexural strength. SX-1-HSHM fiber orientation follows the machine direction and can raise the ratio of machine-direction to cross-direction flexural strength above 1.2:1 unless forming parameters are adjusted.
The substitution decision is controlled by density, elastic modulus, fiber count, interfacial bonding, and chemical durability. Table 2 compares the class-typical envelope for SX-1-HSHM with common alternative fibers. SX-1-HSHM does not match the modulus of steel; therefore direct replacement on an equal volume basis will lower post-crack residual flexural strength measured under ASTM C1609/C1609M-19a. The offsetting properties are corrosion resistance, electrical non-conductivity, lower density, and a much higher fiber count per kilogram.
| Fiber type | Density (g/cm³) | Tensile strength (MPa) | Tensile modulus (GPa) | Elongation (%) | Matrix interaction | Main limitation |
|---|---|---|---|---|---|---|
| SX-1-HSHM (HSHM PVA fiber class) | 1.28–1.30 | 1,200–1,600 | 30–43 | 6–10 | Hydroxyl-rich hydrogen bonding | Moisture regain; lower modulus than steel |
| General-purpose PVA staple | 1.26–1.30 | 600–900 | 10–20 | 15–25 | Hydroxyl-rich hydrogen bonding | Lower crack-bridging stiffness |
| Polypropylene monofilament | 0.90–0.91 | 300–600 | 3–8 | 15–30 | Hydrophobic; low chemical bond | Low interfacial load transfer |
| Cold-drawn steel fiber | 7.85 | 1,000–1,500 | 200 | 1.5–3.0 | Mechanical anchorage | Corrosion risk; high density |
| AR glass fiber | 2.68 | 1,700–3,500 | 72 | 2.5–4.8 | Cementitious bond | Alkaline attack unless ZrO₂-rich |
At a nominal diameter of 14 µm and cut length of 12 mm, SX-1-HSHM provides approximately 4.2×10⁸ fibers per kilogram based on a density of 1.30 g/cm³. A cold-drawn steel fiber of 0.2 mm diameter and equivalent length provides approximately 3.4×10⁵ fibers per kilogram. This difference improves spatial distribution and plastic shrinkage crack control, but does not compensate for the lower tensile modulus in structural post-crack design. Against polypropylene, SX-1-HSHM provides roughly three to five times the tensile strength and approximately five to ten times the tensile modulus; the hydroxyl-rich surface also reduces fiber pullout at small crack openings. Against AR glass fiber, SX-1-HSHM lowers the composite modulus but avoids the long-term alkaline hydrolysis risk associated with insufficient zirconia content in glass fiber.
In engineered cementitious composites, the fiber–matrix bond must be tuned so that crack opening initiates fiber pullout rather than fiber rupture. If the bond is too strong, failure is dominated by fiber fracture and tensile strain capacity falls. HSHM PVA fiber often carries a proprietary oiling agent or surface treatment to control chemical bond; the oil content should be measured by solvent extraction and compared with the certificate target range. Deviation from the specified oil range changes interfacial toughness and can suppress multiple cracking. For this reason SX-1-HSHM is not directly interchangeable with a general-purpose PVA monofilament or with polypropylene fiber in strain-hardening mix designs.
Storage and processing boundaries are set by the hydrophilic surface and thermal decomposition behavior. Moisture regain at 65% RH is typically 3–5 wt%; opened bags should be stored dry, and pre-drying at 80–100 °C is required when ambient RH exceeds 60% before the fiber is used in moisture-sensitive polymer compounding. SX-1-HSHM is stable in the high-alkali environment of portland cement pore solution, but continuous exposure to strong oxidizing acids is not recommended. Continuous operating temperature should remain below 200 °C; the fiber decomposes near its melting point and is not melt-processable as a neat thermoplastic. In cementitious systems, SX-1-HSHM should not be specified as primary structural tensile reinforcement unless strain-hardening behavior and long-term durability are validated by direct tensile testing on the production mix.
