| HS Code | 807929 |
| Fiber Type | High-tenacity high-modulus polyvinyl alcohol (PVA) fiber |
| Tenacity Cn Per Dtex | 14-15 |
| Initial Modulus Cn Per Dtex | 350-450 |
| Elongation At Break Percent | 5-7 |
| Fiber Diameter Um | 15-25 |
| Fiber Length Mm | 6-12 |
| Melting Point Degc | 220-230 |
| Decomposition Temperature Degc | above 250 |
| Moisture Regain Percent | 4-5 |
| Alkali Resistance | excellent resistance to alkaline environments |
| Acid Resistance | good resistance to weak acids; limited resistance to strong acids |
| Uv Resistance | good resistance to ultraviolet light |
| Solvent Resistance | excellent resistance to common organic solvents |
As an accredited Shuangxin SX-2-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 | Shuangxin SX-2 HSHM PVA Fiber is supplied in 25 kg woven bags with PE liner, palletized and stretch-wrapped. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Shuangxin SX-2 High Tenacity High Modulus PVA Fiber, securely packed for safe transport and delivery. |
| Shipping | Ship as packaged in dry, sturdy woven bags or cartons with inner plastic liners. Store away from moisture, heat, and open flame. Protect from mechanical damage during transit. Ensure proper ventilation and secure loading. No special hazardous material requirements, but follow standard safe handling practices for chemical fibers. |
| Storage | Store in a cool, dry, well-ventilated area away from direct sunlight, heat sources, and moisture. Keep in original sealed packaging or clean, dry containers, off the floor on pallets. Avoid excessive compression, sharp objects, and contact with acids, alkalis, or oxidizing agents. Maintain moderate temperature and humidity to preserve fiber tenacity and modulus. |
| Shelf Life | Shelf life is typically 12 months when stored in a cool, dry, well-ventilated area, protected from moisture and sunlight. |
In engineered cementitious composite production, Shuangxin SX-2 HSHM PVA fiber is introduced at fiber volume fractions normally set between 1.5% and 2.0% during the final high-shear mixing stage after cement, Class F fly ash, silica sand with a maximum particle size below 300 µm, water, and polycarboxylate ether high-range water-reducing admixture have formed a homogeneous slurry. The water-to-binder ratio is typically held between 0.24 and 0.30, and a viscosity-modifying admixture is used to suspend the fiber during placement. Mixing is carried out in a counter-current pan mixer or planetary paddle mixer with variable rotor speed; fiber is added at a controlled feed rate below approximately 1.5 kg/min per 100 L batch to avoid bundle entanglement. After fiber addition, the batch is mixed for an additional 90–120 s at rotor speeds not exceeding 400 rpm. Fresh mortar flow is verified in accordance with ASTM C1437-20, with acceptable flow values for thin-section casting generally between 180 mm and 220 mm. Hardened flexural performance is evaluated by ASTM C1609/C1609M-19a using 100 mm × 100 mm × 350 mm beams under third-point loading. Published data for comparable high-tenacity PVA fiber of 12 mm cut length in ECC report first-crack flexural strengths of 3.5–5.0 MPa, ultimate flexural strengths of 8.0–11.0 MPa, and residual strengths at net deflection L/150 above 3.0 MPa. Uniaxial tensile strain capacity is commonly reported in the range of 3.0–5.0% when displacement-controlled testing is performed at 0.5 mm/min. The critical processing boundary is fiber volume fraction: below approximately 1.2% the mix loses tensile strain-hardening capacity, while above 2.2% the probability of fiber balling, flow collapse, and void formation increases rapidly unless wetting agent and mixing time are precisely adjusted. Batch-specific tensile strength, modulus, and cut-length values should be taken from the manufacturer certificate of analysis, because fiber-to-matrix bond is sensitive to surface sizing and filament diameter.
| Fiber volume fraction | Fresh flow ASTM C1437-20 | First-crack flexural strength ASTM C1609 | Ultimate flexural strength | Residual strength at L/150 | Tensile strain capacity |
|---|---|---|---|---|---|
| 1.2% | 180–210 mm | 3.0–4.0 MPa | 6.0–8.0 MPa | 2.0–3.0 MPa | 1.0–2.0% |
| 2.0% | 150–190 mm | 3.5–5.0 MPa | 8.0–11.0 MPa | 3.5–5.5 MPa | 3.0–5.0% |
The replacement of refined virgin kraft pulp in autoclaved fiber-cement board production requires a different retention and refining strategy because the synthetic fiber contributes tensile reinforcement without the water-holding and fibrillation function of cellulose. In Hatschek machine processing, HSHM PVA fiber is charged at 1.5–3.0 wt% of total furnish solids using 6 mm or 8 mm chopped fiber, while cellulose refining is reduced to maintain sheet formation and vacuum drainage. The fiber is added as dry chopped strand directly to the feed tank or pre-dispersed in water at pH between 6.5 and 8.0 before mixing with Portland cement, ground silica, and cellulose pulp. Retention on the rotary sieve cylinders is primarily mechanical, and fiber length must not exceed approximately 40% of the forming layer thickness to avoid washboard formation and poor interlaminar bonding. Board forming is carried out on a Hatschek machine with three-cylinder vat configuration and forming roll pressure maintained between 0.4 MPa and 0.6 MPa. Autoclave curing is performed at saturated steam temperature from 170°C to 180°C under pressure of 0.8–1.0 MPa for 6–10 h; the highly crystalline PVA fiber retains tensile strength under these conditions, but sustained temperature above 200°C causes measurable modulus loss and discoloration. Product verification follows ISO 8336:2017 for flat fiber-cement sheets, with additional bending tests evaluated by ASTM C1185-08a. The main process conflict is drainage: at substitution levels above 3.0 wt%, fine fiber segments can blind the sieve surface, reduce dewatering rate, and extend cycle time beyond the operating window of continuous sheet machines unless vacuum box settings and flocculant dosage are re-optimized.
During dry-mix shotcrete placement, HSHM PVA fiber is pre-blended with washed concrete sand, microsilica, and ordinary Portland cement before the mixture enters a rotary gunite feed bowl; fiber dosage is usually maintained between 0.5% and 1.0% by volume, with cut length limited to 6–8 mm to prevent nozzle blockage in 38–50 mm delivery hoses. Water is introduced only at the nozzle through a perforated spray ring, and the water pressure is held 0.1–0.2 MPa above the air pressure to achieve uniform wetting without washing the fiber from the dry stream. Published field data for polymer fiber shotcrete indicate that fiber addition at 0.5 vol% can reduce rebound from approximately 20–35% to 12–20% on vertical and overhead surfaces, although the reduction depends on nozzle distance, aggregate grading, and air flow. The hardened sprayed concrete is evaluated by EN 14488-3:2006 for flexural strength and residual strength of fiber-reinforced beam specimens, and compressive strength is checked by EN 12390-3. This application is less sensitive than ECC to tight rheological limits, but field experience shows that fiber lengths above 12 mm and fiber volume fractions above 1.0% increase the risk of aggregate pocketing at the nozzle tip and uneven pneumatic transport.
Two-stage internal mixing is used to incorporate HSHM PVA fiber into conveyor belt skim rubber without excessive fiber breakage. In a Banbury internal mixer with tangential rotor configuration, the fiber is added during the second mixing stage at 2–6 phr with cut length usually between 4 mm and 6 mm, after carbon black and process oil have been dispersed into the polymer matrix. The HSHM fiber is pretreated with a two-stage resorcinol-formaldehyde-latex dip, producing a dry solids pickup between 3% and 6% on fiber weight, which promotes adhesion to the rubber matrix during vulcanization. Curing is performed at temperatures from 150°C to 170°C, and the compound is characterized by tensile stress-strain properties under ISO 37:2017. Belt carcass adhesion is tested by ISO 252:2017 or the equivalent ply adhesion method specified for the belt class. The operational boundary is vulcanization temperature: above approximately 180°C, the PVA fiber begins to lose tensile integrity at a rate that can reduce carcass tear strength after extended cure cycles. The fiber is therefore not recommended for compounds requiring high-temperature post-cure above 200°C or those using amine-based accelerators that promote alkaline hydrolysis at the fiber-rubber interface.
Preform strength is the controlling variable when HSHM PVA fiber is charged into non-asbestos organic friction material formulations for disc brake pads and drum linings. The fiber is dispersed in a ploughshare mixer with Novolac phenolic resin, hexamethylenetetramine, barite, calcium carbonate, cashew friction dust, and steel fiber; PVA fiber addition is normally between 2 wt% and 6 wt% of total dry compound, with cut lengths from 3 mm to 6 mm. Mixing proceeds for 8–15 min at nominal rotor speeds below 120 rpm because higher shear fractures the synthetic fiber and reduces green preform strength. Cold preforming is carried out at 20–30 MPa and room temperature, followed by hot pressing in a multi-cavity compression mold at 140–160°C under 15–25 MPa. The fiber improves preform handling strength before thermoset cure, which reduces edge chipping during mold loading. Friction performance is evaluated with ISO 26867:2009 or SAE J2522 dynamometer procedures, and coefficient of friction values are reported over the designated braking pressure and temperature profile. Processing limitations are explicit: PVA begins to decompose above approximately 200°C, releasing water and acetic acid; therefore press platen temperatures above 180°C and post-cure ovens above 200°C require forced ventilation and are generally outside the recommended operating window. Formulations requiring extended post-cure above 230°C should not use this fiber unless the organic fiber fraction is isolated from the thermal cycle by staged cure profiles.
Wet-laid technical paper and filtration media can incorporate 5–15 wt% of 4 mm HSHM PVA fiber as a synthetic reinforcing furnish component, subject to stock pH above 4.0 and drying calendar temperatures below 180°C to preserve filament integrity.
The addition of HSHM PVA fiber to a stiff extrudable mortar changes the relationship between progressive cavity pump screw speed and nozzle back-pressure, dictating the maximum fiber volume fraction that can be used in additive manufacturing. In laboratory-scale 3D concrete printing with a 20 mm circular nozzle and layer height of 10 mm, fiber dosage is normally limited to 1.25–1.75 vol% using 6 mm cut fiber to avoid excessive pump pressure and layer splitting. The water-to-binder ratio is held near 0.26–0.30, and a thixotropic viscosity-modifying admixture is added to maintain extrusion shape stability after deposition. Screw speed is typically maintained between 30 rpm and 60 rpm, with back-pressures below approximately 20 bar; above this threshold, the extrusion rate becomes unstable and surface tearing occurs at the nozzle exit. Fiber orientation aligns preferentially along the print direction due to shear-induced orientation in the nozzle, producing anisotropic flexural response. Flexural testing is performed by ASTM C1609/C1609M-19a on specimens cut parallel and perpendicular to the printed filament; published data for extruded mortar with short PVA fiber indicate higher residual load capacity in the longitudinal direction than in the transverse direction. The critical processing window is narrow because the fiber must be long enough to bridge microcracks but short enough to pass through the nozzle without clogging. At 1.75 vol%, print surface quality can still be maintained if nozzle standoff distance is kept between 8 mm and 10 mm; at higher fiber volume fractions, pump pressure rises sharply and layer cold joints become visible under digital microscopy.
| Application segment | Primary standard designation | Typical fiber addition | Critical processing boundary |
|---|---|---|---|
| Engineered cementitious composite | ASTM C1609/C1609M-19a | 1.5–2.0 vol% | Flow below 150 mm |
| Autoclaved fiber-cement board | ISO 8336:2017 | 1.5–3.0 wt% | Autoclave temperature above 200°C |
| Dry-mix shotcrete and repair mortar | EN 14488-3:2006 | 0.5–1.0 vol% | Fiber length above 12 mm |
| Rubber conveyor belt skim compound | ISO 37:2017 | 2–6 phr | Vulcanization above 180°C |
| Non-asbestos organic friction material | ISO 26867:2009 | 2–6 wt% | Post-cure above 200°C |
| 3D printed mortar | ASTM C1609/C1609M-19a | 1.25–1.75 vol% | Pump pressure above 20 bar |
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Shuangxin SX-2-High Tenacity High Modulus PVA Fiber（HSHM PVA Fiber）is a polyvinyl alcohol monofilament reinforcement produced for cementitious matrices requiring tensile strength, elastic modulus, and controlled elongation at break above the limits of general-purpose polyvinyl alcohol staple grades. The designation SX-2 identifies a high-tenacity high-modulus variant formed by wet spinning, hot drawing, and surface finishing. The product is supplied in cut lengths of 6 mm and 12 mm and is dispersed into mortar or concrete before the addition of high-range water-reducing admixture. Primary applications include strain-hardening cementitious composites, tunnel linings, shotcrete, and impact-resistant slabs where a low-density, alkali-stable synthetic fiber must provide crack-bridging stress without the corrosion risk of steel fiber.
Vendor-published representative values for SX-2 HSHM PVA fiber are presented in Table 1; acceptance criteria must be confirmed against the batch certificate because wet-spinning draw ratio, drying profile, and finish chemistry affect the measured single-filament properties. The fiber is characterized by a nominal tensile strength of 1,500 MPa, an elastic modulus near 40 GPa, and an elongation at break of 6.5% under ISO 2062 single-filament testing. Density is approximately 1.30 g/cm³, which allows the fiber to remain suspended in low-viscosity cement paste without the segregation exhibited by higher-density steel fiber.
| Property | Test method | SX-2 HSHM PVA fiber | General-purpose PVA fiber |
|---|---|---|---|
| Tensile strength | ISO 2062 | 1,400–1,600 MPa | 900–1,100 MPa |
| Elastic modulus | ISO 2062 | 35–42 GPa | 22–28 GPa |
| Elongation at break | ISO 2062 | 6.0–7.5% | 8–12% |
| Density | ISO 1183-1 | 1.29–1.31 g/cm³ | 1.26–1.30 g/cm³ |
The narrower elongation range of SX-2 HSHM PVA fiber is functionally significant: it places the fiber in the high-modulus region where crack-bridging stress develops rapidly at 0.5–1.0 mm crack openings in cementitious matrices, whereas general-purpose PVA fiber with higher elongation undergoes greater deformation before mobilizing the same bridging force. In strain-hardening cementitious composites, SX-2 HSHM PVA fiber is typically added at 1.0–2.0 vol%. Published ECC research using high-tenacity high-modulus PVA fibers reports tensile strain capacity from 3% to 6% when the matrix is proportioned with water-to-binder ratio near 0.45, silica fume replacement, and polycarboxylate ether superplasticizer. The same literature identifies an upper practical limit: beyond 2.0 vol%, the benefits of increased fiber volume are partially offset by reduced matrix workability, higher air content, and greater fiber-ball formation unless mixing energy is increased substantially.
In dry-mix shotcrete and tunnel lining applications, the fiber is introduced at the batching plant or at the nozzle through a metered feed. Field observations indicate that fiber rebound can remove 20–40% of loose synthetic fiber if the feed rate is not adjusted for the higher aspect ratio of the 12 mm monofilament. The product is not a replacement for steel fiber in every use: post-peak flexural capacity in structural concrete remains lower than that of steel-fiber-reinforced concrete because the absolute modulus of PVA fiber is lower, but the composite avoids chloride-induced corrosion and provides better chemical resistance in wet tunnel environments.
On production-scale twin-shaft compulsory mixers with capacity of 500 L, SX-2 HSHM PVA fiber has shown better dispersion when added to dry aggregate before water, rather than to a finished slurry. High-shear mixing for 180–240 s after fiber addition separates individual monofilaments; mixing beyond 360 s can increase fiber breakage and abrade the size finish, reducing cement-fiber affinity. Batch-to-batch variance is observed when fiber opening is incomplete at the point of water addition, and the resulting fiber agglomerates can remain intact through 90 s of standard mixing. In a pan mixer of 250 L capacity, pre-dispersing the fiber with a portion of the fine aggregate for 60 s before adding cement and water reduces agglomeration in mixes containing 2.0 vol% fiber.
Slump reduction is proportional to fiber volume fraction and aspect ratio. For 6 mm SX-2 HSHM PVA fiber at 1.0 vol%, ASTM C143/C143M slump values typically decrease by 40–60 mm relative to the same matrix without fiber; the required polycarboxylate ether dosage increases by 0.5–1.0 kg/m³. For 12 mm fiber at 2.0 vol%, the slump reduction can reach 70–100 mm, and published data for SX-2-specific slump retention across all mixer types is limited; site calibration is therefore required. The practical upper addition level is constrained by workability rather than fiber tensile capacity. At 2.5 vol%, a matrix with aggregate volume fraction above 0.35 and paste volume below 0.60 can become unworkable unless the mix is redesigned with lower coarse aggregate and increased paste.
The fresh-state rheology is further influenced by the surface size on the fiber. PVA fiber with a size system that dissolves too rapidly can create a local viscosity spike around each monofilament, while a size that dissolves too slowly leaves fiber bundles intact and reduces effective fiber count. For SX-2 HSHM PVA fiber, the manufacturer’s finish is designed for compatibility with polycarboxylate ether and naphthalene-based superplasticizers, but combinations with amine-based admixtures should be avoided without plant-scale compatibility testing because pH shifts above 13 can alter dispersion behavior and leave unhydrated cement agglomerates attached to fiber bundles.
The difference between SX-2 HSHM PVA fiber and general-purpose PVA fiber is primarily the draw ratio and resulting tensile modulus. SX-2 HSHM develops tensile strength of approximately 1,500 MPa and elastic modulus of approximately 40 GPa, while general-purpose PVA grades typically exhibit 900–1,100 MPa tensile strength and 22–28 GPa modulus. This difference changes the failure mode in cement-based materials: high-modulus PVA fiber can transfer stress across microcracks without excessive elongation, allowing strain-hardening behavior at lower fiber volumes. General-purpose PVA fiber, with its higher elongation and lower modulus, is more commonly used for plastic shrinkage crack control rather than structural microcrack bridging.
Compared with steel fiber, SX-2 HSHM PVA fiber has lower absolute modulus—40 GPa versus approximately 200 GPa for steel—but a density of approximately 1.30 g/cm³ versus 7.85 g/cm³ for steel. The specific tensile strength of SX-2 HSHM PVA fiber is therefore higher in mass-based terms, and the finished composite does not exhibit ferrous staining or chloride-induced corrosion. The lower stiffness must be considered in structural applications requiring post-peak flexural capacity, where steel fiber remains the stiffer reinforcement. In aggressive water and tunnel drainage environments, however, the PVA fiber eliminates the maintenance problems associated with exposed steel fiber corrosion at crack surfaces.
Compared with polypropylene fiber, SX-2 HSHM PVA fiber has a much higher tensile strength—1,400–1,600 MPa versus 300–600 MPa—and a much higher elastic modulus—35–42 GPa versus 3–8 GPa. Polypropylene fiber is hydrophobic and can reduce cement adhesion, whereas PVA fiber is hydrophilic and forms a stronger interfacial bond with cement paste. This bond improves early crack control but also reduces the ease of post-cracking fiber pullout; the balance is tuned through the surface finish on SX-2 HSHM fiber. In applications such as impact-resistant slabs, the higher strength and modulus of SX-2 HSHM PVA fiber provide greater energy absorption than polypropylene fiber at equal volume fractions, but the trade-off is lower workability and a greater need for water reducer adjustment.
Among high-modulus PVA fibers from different producers, SX-2 HSHM PVA fiber is differentiated by the proprietary surface finish, cut-length consistency, and stated tensile property profile. Published comparative data for all competitor grades is limited, so direct substitution should be based on the batch certificate and a full-scale mixer trial rather than on nominal datasheet values alone. The fiber geometry, finish content, and modulus interact with the matrix such that two products with identical datasheet tensile strength can perform differently in the same ECC mix if the interfacial bond differs.
| Standard or regulation | Scope | Typical requirement |
|---|---|---|
| EN 14889-2:2006 | Polymer fibres for concrete | Geometry, tensile strength, modulus, alkali resistance; batch certificate required |
| ASTM C1116/C1116M-10a | Synthetic fiber-reinforced concrete | Type III synthetic fiber classification; dosage and mixing compliance |
| ISO 2062 | Single-filament tensile properties | Tensile strength, elongation at break, modulus |
| ISO 1183-1 | Plastics density | Density determination for material handling |
| REACH Regulation (EC) No 1907/2006 | Chemical safety | Substance registration and safety data sheet compliance |
| RoHS Directive 2011/65/EU | Hazardous substances in electrical/electronic equipment | Not required for construction products; optional testing for Pb, Cd, Hg, Cr(VI), PBB, PBDE |
Published data for SX-2-specific performance in ultra-high-performance concrete is limited; therefore, the values in Table 1 and the workability ranges above should be validated with a plant trial using the actual cement, supplementary cementitious materials, and mixer retention time. The product should not be combined with amine-based admixtures without compatibility testing, and storage at relative humidity above 60% requires pre-drying at 60 °C for 2 h to prevent microfilament aggregation. Fiber addition should be re-validated whenever the source of supplementary cementitious material changes, because fly ash-fired carbon content and silica fume surface area can shift the effective water demand and alter dispersion of the high-modulus monofilaments.
