ArcBiox™ SGF15-A1 is a short glass fiber reinforced injection molding grade of polylactic acid with a nominal glass fiber content of 15% by weight. The glass reinforcement is a chopped-strand fiber with a typical filament diameter of 10–14 µm and a silane-based sizing intended to improve interfacial adhesion with the PLA ester backbone; the specific sizing chemistry is listed in the product technical data sheet. The matrix is a high-purity PLA with a compounded melt volume-flow rate commonly reported at 210°C under 2.16 kg in the range of 6–12 cm³/10 min when tested in accordance with ISO 1133-1:2022. Because the actual lot-to-lot MVR varies with moisture content, fiber length distribution, and compounding history, processing personnel should verify the certificate of analysis before setting shot size or fill time.

Typical solid-state density for a 15 wt% short glass fiber PLA compound is 1.28–1.35 g/cm³ when measured under ISO 1183-1:2019. The filled grade is intended for injection molding of rigid housings, frames, brackets, and mechanical components that require reduced mold shrinkage and elevated heat deflection relative to unfilled PLA. The product is not formulated for blown film, cast film, or fiber spinning. Published data for this specific configuration is limited, but the property envelope below is representative of short glass fiber PLA injection compounds in the 15 wt% loading class and should not be read as a specification without lot-specific qualification.

The notched Izod values remain constrained by the inherent brittleness of PLA; glass fiber does not provide elastomeric toughening. Components subjected to snap-fit insertion or impact loading may require enlarged notch radii, reduced gate stress concentration, or a shift to an impact-modified PLA grade. The property table should not be used as a direct substitute for part-specific testing because fiber orientation, weld-line location, and mold temperature history can shift each value by more than the indicated range width.

What separates SGF15-A1 from unfilled PLA and mineral-filled compounds?

Compared with unfilled PLA, the 15 wt% glass fiber raises tensile modulus by approximately 60–120% and flexural modulus by a similar factor, while heat deflection temperature under 0.45 MPa increases from the 50–60°C range to 95–130°C after annealing or with heated mold conditions. Mold shrinkage measured under ISO 294-4 is reduced to roughly 0.2–0.5% in the flow direction, but becomes anisotropic: cross-flow shrinkage can remain 0.4–0.7%, a major source of out-of-plane warpage in flat covers and thin-wall trays.

Relative to talc-filled PLA, the glass fiber system yields higher tensile and flexural strength at equivalent filler weight, lower density, and better property retention at elevated temperature. However, talc-filled PLA can provide more isotropic shrinkage and lower mold wear. Glass fiber is abrasive; processing on hardened screws, barrels, and check rings with wear-resistant coatings is required to avoid progressive screw recovery drift and non-return valve leakage during multi-cavity filling.

Compared with long glass fiber PLA pellets, the SGF15-A1 short fiber distribution allows better flow into ribs as thin as 1.2 mm and produces a smoother visible surface, but notched impact and energy absorption are lower. If impact loading is the primary design requirement, a long-fiber reinforced or impact-modified grade should be evaluated before committing to SGF15-A1.

Melt rheology, screw selection, and shot-size control

Compounded short glass fiber PLA is shear-thinning; increasing injection velocity reduces apparent melt viscosity but also raises frictional heat and the risk of hydrolysis. A three-zone general-purpose screw with L/D 20:1–24:1 and compression ratio 2.0:1–2.5:1 is typically used. For shot sizes above 30% of barrel capacity, melt residence time should be kept below 8 min at melt temperatures above 200°C. The glass fiber length decreases during plastication; screw speeds above 80 rpm and back pressures above 0.7 MPa can reduce average fiber length and lower final tensile modulus. A medium check ring with wear-resistant surfaces is recommended because fiber-filled PLA can wedge in standard ball-check valves and cause inconsistent cushion.

At 210°C and an apparent shear rate of 1,000 s⁻¹, the apparent viscosity for a 15 wt% short glass fiber PLA compound is commonly in the range of 80–150 Pa·s; capillary rheometry per ISO 11443 should be used for mold-filling simulation input rather than MVR data alone. Injection pressure at the machine hydraulic cylinder typically falls between 80–120 MPa, with hold pressure set at 50–70% of the peak injection pressure until gate freeze.

Drying prior to injection molding is mandatory when exposure to ambient air above 60% relative humidity has occurred. PLA undergoes hydrolytic chain scission at melt temperatures above 200°C if moisture content exceeds 250 ppm. A desiccant dryer with dew point at or below -40°C and air temperature 80°C for 4 h is typical; drying times of 6–8 h may be used after opened storage, but temperatures above 90°C can cause pellet softening and bridging in the hopper. After drying, the material should be conveyed with dry air and fed from a hopper with minimal open-air exposure. The processing window for melt temperature is narrow: 190–210°C at the nozzle. Residence time above 220°C should not exceed 5 min; above 230°C, thermal degradation and lactide formation produce visible silver streaks, reduced melt strength, and acidic by-products that can accelerate mold deposit formation.

Mold temperature control deserves particular attention. At mold temperatures below 60°C, the PLA matrix remains largely amorphous and the heat deflection benefit of the glass fiber is reduced. For maximum heat resistance, parts are annealed at 90–110°C for 30–60 min after molding, or the mold is held at 80–100°C with sufficient cooling time for crystallization. Annealing fixtures are required for flat parts because unrestrained parts can distort during the crystallization step.

When cavity wall shear rates exceed 100,000 s⁻¹, fiber orientation and gate design control warpage

Glass fiber orientation follows the melt front and is determined by gate geometry, melt temperature, and fill speed. In flat rectangular parts with edge gates, the flow-direction orientation produces higher stiffness along flow but also lower shrinkage; the cross-flow direction retains higher shrinkage. For parts with wall thickness below 2 mm, injection speeds are often raised to avoid premature freeze-off, which drives wall shear rates above 100,000 s⁻¹. Under these conditions, the skin layer becomes highly oriented while the core remains less oriented. Differential shrinkage between skin and core leads to warpage that cannot be corrected by pack pressure alone. Mold temperature uniformity above ±5°C is often more important than absolute mold temperature in controlling flatness; cooling circuits should be balanced and documented with in-mold thermocouples.

Typical cavity pressure at switchover is 40–70 MPa. Hold pressure is maintained until gate freeze; gates smaller than 1.0 mm may freeze before packing is complete and require increased gate diameter or reduced fiber content. For multi-cavity tools, the runner system should be geometrically balanced; glass fiber orientation shifts the effective viscosity, and naturally balanced layouts can still produce cavity-to-cavity fill variation if gate lands are not identical.

ArcBiox™ SGF15-A1 is used in injection-molded electronic device housings, conveyor guide rails, agricultural sensor enclosures, and structural interior components where moderate stiffness and reduced petroleum-based polymer content are specified. It is not recommended for continuous immersion in water above 60°C, because PLA hydrolyzes at accelerated rates; in such conditions, a hydrolysis-resistant polyester or polyamide is more appropriate. It is also not recommended for load-bearing components with notched Izod impact below 6 kJ/m² unless the design eliminates sharp corners and knit lines are moved away from tensile stress concentrations.

Bio-based carbon content of the PLA matrix can be verified by ASTM D6866 or EN 16640. The inorganic glass fiber fraction is not biodegradable; therefore, the compound may not satisfy the disintegration and ecotoxicity requirements of EN 13432 or ASTM D6400 unless specifically certified by the manufacturer. For industrial composting claims, certification must be based on the final compound, not the neat PLA resin. The glass fiber residue remains after polymer biodegradation and must be accounted for in disposal and recovery planning.