Biolloy KG340 High Rigidity General Purpose Polylactic Acid/ABS Alloy is a compounded melt blend of polylactic acid and acrylonitrile-butadiene-styrene positioned for injection molding applications in which flexural modulus, dimensional consistency, and a partially renewable carbon fraction are evaluated together. The model designation KG340 identifies a high-rigidity, general-purpose grade within the Biolloy family. The formulation is intended to increase elastic modulus and flexural strength above standard ABS while avoiding the severe notch sensitivity and edge cracking associated with neat PLA. Product-specific lot data for tensile behavior, impact resistance, melt flow rate, and mold shrinkage should be obtained from the supplier technical datasheet; the values discussed below are class-level ranges for high-rigidity PLA/ABS alloys and are not a substitute for KG340 certificate of analysis values.

The material is normally supplied as cylindrical pellets in moisture-barrier packaging. On production-scale injection molding lines, inadequate drying is the most common source of surface splay, gate blush, and molecular weight reduction from ester hydrolysis. The melt contains ABS domains dispersed in a PLA-rich matrix or co-continuous phases depending on composition and shear history. High-rigidity versions of this class retain a high proportion of high-modulus PLA phase, which raises flexural modulus but narrows the ductile deformation window. If the material is processed without a desiccant dryer having a dew point below −30°C, equilibrium moisture uptake can exceed 0.2% and hydrolysis accelerates above 220°C. Drying at 70–80°C for 4 h is the minimum practical target in production; above 60% relative humidity, drying time should be extended to 6 h or the hopper kept under dry air to reach a residual moisture content below 0.02% by Karl Fischer titration.

What Distinguishes KG340 from Standard ABS, Neat PLA, and PC/ABS in Part Design?

Compared with standard ABS, the high-rigidity PLA/ABS class typically raises flexural modulus from the 1,900–2,500 MPa range to 2,800–3,400 MPa under ISO 178:2019. Compared with neat PLA, the ABS phase increases Charpy notched impact from the 2–4 kJ/m² range to 7–15 kJ/m² under ISO 179-1/1eA and reduces sharp-edge fracture during ejection. Compared with PC/ABS, the PLA/ABS alloy shows lower heat deflection temperature and should not be treated as a direct substitute for continuous service above 80°C. Compared with impact-modified PLA/PBAT or flexible PLA compounds, KG340 is on the stiff end of the portfolio; elongation at break is generally below 10%, and the grade is selected for structural rigidity rather than snap-deformation capacity. The exact KG340 additive system is proprietary, but the property envelope indicates a compatibilized PLA/ABS morphology rather than an immiscible binary blend with low interfacial adhesion.

In injection molding trials on a 1,200 kN hydraulic clamp machine using a 30:1 L/D general-purpose screw, barrel profiles of 170–190°C in the feed zone, 180–210°C in the compression zone, 190–220°C in the metering zone, and 200–230°C at the nozzle are used. Melt temperature measured by air shot is normally maintained between 210°C and 230°C. Residence time above 230°C should remain below 8 min because PLA undergoes thermal depolymerization and discoloration; short shots and gate blush increase when the melt is held at temperature. Back pressure of 5–8 bar and screw speed of 80–150 rpm improve melt consistency without generating excessive shear heat. Mold temperature between 25°C and 50°C balances surface gloss and cycle time; higher mold temperatures can improve weld line strength but slow cooling of thin features.

Mechanical Property Envelope and the High-Rigidity Classification

The term high rigidity is not a standardized material class. In the Biolloy portfolio it is generally understood as a flexural modulus above 2,800 MPa after conditioning at 23°C and 50% relative humidity according to ISO 291:2008. The table below provides the typical property envelope for high-rigidity PLA/ABS injection molding grades of this type. These values are class-level ranges reported in supplier technical bulletins and peer-reviewed polymer literature; published data for the exact KG340 configuration is limited, so the manufacturer datasheet remains mandatory for part qualification.

Within the KG340 high-rigidity class, density is typically lower than neat PLA due to the ABS fraction, often 1.08–1.16 g/cm³. Tensile strength under ISO 527-2/1A is commonly 46–56 MPa; the material is formulated for stiffness-driven parts rather than tensile ductility. The notched Charpy value is intermediate between neat PLA and standard ABS, which means snap fits must be designed with larger radii and lower deflection than standard ABS. Heat deflection temperature under 1.8 MPa load is normally 65–85°C; short-term excursions above 120°C are not recommended for load-bearing features. Differential scanning calorimetry of PLA/ABS blends often shows two glass transitions, with the PLA phase near 55–65°C and the ABS phase near 100–110°C, although dynamic mechanical analysis may resolve broader damping peaks. This two-phase structure contributes to the high modulus but also creates a narrower processing window than standard ABS when high shear or high temperature is applied.

For thin-wall electronics housings and display bezels, the grade is evaluated for flatness and boss strength rather than high-impact abuse. Typical mold shrinkage for unfilled high-rigidity PLA/ABS is 0.4–0.7%; if mineral filler is present, shrinkage can fall below 0.4% and warpage can increase along the flow direction. Tooling qualification should use the supplier's published shrinkage range; if no datasheet value is available, prototype cavities should include 0.5% shrink compensation as an initial reference. Gate freeze time is shorter than standard ABS because the melt solidifies more quickly; packing pressure should be raised or gate size increased by 10–20% to prevent sink at rib intersections. Screw retraction during decompression should be minimized to avoid air entrapment and gate stringing.

When KG340 Replaces Standard ABS in Thin-Wall Enclosures and Structural Brackets

Substitution is most viable when the part is stiffness-limited rather than impact-limited. The higher flexural modulus allows a wall-thickness reduction of roughly 0.2–0.3 mm on a 2.0 mm ABS baseline without a proportional loss of stiffness, provided the Charpy notched impact requirement remains within the PLA/ABS class. For structural brackets, the material is used where continuous temperature is below 65°C and intermittent exposure does not exceed 85°C under mechanical load. The most common processing defect observed in this replacement scenario is stress whitening near threaded inserts and snap hooks. Post-molding cracking is reduced by using cold inserts or by increasing wall thickness around the insert by 0.5 mm. If adhesive bonding is required, corona or plasma surface treatment raises polar surface energy; the PLA phase contributes ester functionality, but hydrophobic ABS domains can limit adhesion to water-based systems.

Pre-drying to 0.02% moisture is required before processing. A desiccant dryer with closed-loop regeneration and air dew point below −30°C should be set to 70–80°C for 4–6 h. If pellets are exposed to plant air at relative humidity above 60% for more than 30 min, moisture re-uptake can cause splay and a reduction in average molecular weight. Do not process KG340 in barrels previously used for PVC, acetal, or polyamide without thorough purging; residual acidic or alkaline species can accelerate PLA chain scission. Strongly alkaline additive masterbatches should be evaluated before use because PLA ester linkages are susceptible to base-catalyzed hydrolysis. Storage in sealed bags with desiccant is recommended. Regrind addition is typically possible up to 20 wt%, but repeated extrusion cycles increase melt flow rate and reduce impact, so lot-to-lot variability is controlled by limiting regrind ratio.

Compliance Verification Points Under REACH, RoHS, and UL Material Screening

No single datasheet should be considered a compliance certificate. The following verification matrix summarizes the documentation typically requested before export or appliance-level qualification. KG340-specific declarations for substances of very high concern, RoHS-restricted substances, and flame class must be confirmed by the supplier because copolymer ratio and additive package influence results.

In domestic appliance structural brackets, internal frames, and consumer electronics housings, KG340 is typically selected for stiffness retention after repeated door closures and for a lower carbon footprint than standard ABS. The material is not a drop-in replacement for all standard ABS applications; components requiring more than 15 kJ/m² Charpy notched impact or continuous load above 80°C should remain with impact-modified ABS or PC/ABS. Mold trials should verify ejection force, gate blush, and insert stress before production release. Processors should obtain the supplier's certificate of analysis for melt flow rate, density, and flexural modulus on each lot and retain the material identification code under ISO 11469:2016 on the part drawing.