PURAPOL L130 High Heat Medium Flow PLA Homopolymer is a polylactide material based on a stereoregular L-lactic acid-rich backbon chain. The homopolymer designation indicates low D-isomer content, which permits the formation of semi-crystalline domains under controlled thermal conditions. All numerical intervals below are class-representative for high-heat medium-flow PLA homopolymers and are supplied for initial engineering orientation only. The binding product-specific values are those on the grade technical data sheet and lot certificate.

For preliminary design, high-heat medium-flow PLA homopolymers commonly fall within an ISO 1133-1 melt mass-flow rate at 210 °C/2.16 kg of 10 g/10 min to 25 g/10 min, an ISO 1183 density of 1.24 g/cm³ to 1.27 g/cm³, an ISO 527-2 tensile modulus of 3.0 GPa to 3.8 GPa, and an ISO 75-2 heat deflection temperature after full crystallization of 90 °C to 120 °C depending on wall thickness and annealing history. The medium-flow melt is intended to reduce fill pressure relative to low-flow high-heat PLA grades while retaining enough chain length for crystallization.

How Does the L130 Grade Differ from Standard PLA Homopolymers in Melt Rheology?

Standard PLA homopolymers often contain higher D-isomer contents, typically between 4% and 12%, which disrupt chain regularity and limit crystallinity. In contrast, high-heat PLA homopolymers of the PURAPOL L130 type are formulated or selected for low D-isomer content, frequently below 2%, so that isothermal crystallization half-times at 100 °C to 120 °C may fall below 60 s. Under ISO 11357-1 differential scanning calorimetry, the material class typically shows a cold-crystallization exotherm between 85 °C and 120 °C and a melting endotherm between 165 °C and 180 °C.

The medium-flow characteristic is produced by controlled chain-length reduction during polymerization or compounding. In injection molding, this lowers melt viscosity while preserving sufficient molecular weight for crystallization. On a 40 mm screw and 70-tonne electric injection molding machine, the medium-flow melt can fill thin-wall tools at lower hold pressures than high-heat low-flow grades; however, the pressure reduction is nonlinear because shear heating increases with injection velocity and part thickness decreases. The grade is normally selected where high-heat low-flow PLA produces excessive cavity pressure or where standard PLA fails hot-fill or dishwasher contact.

Before processing, the resin must be dried in a desiccant dryer with a dewpoint at or below −40 °C. Class-typical drying at 85 °C for 4 h may be insufficient for high-heat grades with low D-isomer content; supplier settings often increase the drying temperature to 100 °C to 120 °C for 4 h to 6 h. Residual moisture above 250 ppm measured by Karl Fischer titration can hydrolyze the ester linkage during melt processing. On injection molding machines, barrel profiles from 180 °C at the feed throat to 210 °C at the nozzle are used, with melt temperature kept below 230 °C to avoid rapid viscosity loss. A 20:1 to 24:1 L/D general-purpose screw with a compression ratio of 2.2:1 to 3.0:1 is acceptable. Residence time above 220 °C should not exceed 8 min, and regrind fractions above 30% by mass should require additional moisture and melt-flow verification.

When the Process Requirement Shifts to Annealed Rigid Articles Without Impact Modification

Application conditions for this material class include rigid food-service lids, reusable drinkware, appliance housings, automotive interior trim, and electronics carrier trays. In these parts, the medium-flow rheology permits filling of wall sections down to 1.5 mm on multicavity hot-runner tools at mold temperatures between 90 °C and 120 °C. At these mold temperatures, crystallization may begin in the mold, but full crystallinity is usually completed by post-annealing at 100 °C to 120 °C for 30 min to 60 min depending on wall thickness and tool steel thermal uniformity.

The resulting heat resistance can move the ISO 75-2 method B deflection temperature from an as-molded value of 55 °C to 65 °C to an annealed value of 90 °C to 120 °C. The medium-flow variant offers a substitution route when standard PLA does not survive hot-fill or dishwasher exposure, but it is not a drop-in for cold-impact applications. Notched Izod impact under ISO 180/1A typically remains in the 2 kJ/m² to 4 kJ/m² range unless impact modifiers are added. Impact modification reduces heat resistance and modulus, so the selection requires balancing load conditions against thermal requirements.

Comparative Property Envelope Against Impact-Modified and High-Flow PLA Grades

The table below compares class-representative values across standard PLA, high-heat medium-flow PLA homopolymers of the PURAPOL L130 type, high-flow PLA injection grades, and impact-modified PLA compounds. The values are not supplier-certified data and must be replaced with lot-specific results for production qualification.

Published data for PURAPOL L130-specific high-heat medium-flow PLA configurations are limited in open literature; the property matrix above is therefore a class-level comparison for material selection. Where process conflicts occur, the critical threshold is crystallization cooling rate. If mold temperatures fall below 80 °C, high-heat PLA homopolymers may freeze in an amorphous state, and post-annealing must then be extended. If mold temperatures exceed 120 °C, polycondensation and backbone scission compete, and cycle time increases. On thin-wall articles, the medium-flow melt can reduce cavity fill pressure by approximately 10% to 20% relative to low-flow high-heat grades, but the reduction is not linear.

The grade is not suitable for elastomeric snap-fit geometries or cold-impact housings without impact modification. Amine-containing colorants, certain metal stearate lubricants, and aqueous ink systems can accelerate chain scission under shear. Compatibility trials should include melt-flow retention under ISO 1133-1 and notched impact retention under ISO 180/1A before production.

Regulatory status is formulation-specific. If the grade is supplied with a compliance declaration for food-contact use, relevant instruments include Commission Regulation (EU) No 10/2011 for plastics intended to come into contact with food and applicable FDA 21 CFR food-contact notifications for PLA. For general industrial use, compliance under REACH (EC) No 1907/2006 and the RoHS Directive 2011/65/EU requires supplier confirmation of candidate list substances and restricted heavy metals. These documents should be tied to lot number, not assumed from the grade name.

Sheet extrusion of the high-heat medium-flow material is possible on single-screw extruders with 24:1 to 36:1 L/D and melt temperatures of 190 °C to 210 °C. The medium-flow viscosity supports gauge uniformity down to 1.0 mm on polished cooling rolls. Crystallization in sheet is suppressed by chill roll temperatures below 60 °C; subsequent thermoforming requires oven heating above 90 °C to permit crystallization during forming. The formed part is then annealed in a fixture at 100 °C to 120 °C to prevent warpage.

Processing boundary conditions are summarized in the following matrix. Values are class-typical for high-heat medium-flow PLA homopolymers; the supplier technical data sheet for PURAPOL L130 is the binding source for settings.

Annealing uniformity is best confirmed by differential scanning calorimetry. A molded article showing an ISO 11357-1 cold-crystallization exotherm above 5 J/g is not fully crystallized and may fail hot-fill or dishwasher tests. The same condition may cause post-shrinkage in service.