LyondellBasell HDPE FLP 3714 is a high-density polyethylene resin supplied in pellet form for extrusion blow molding and sheet extrusion. The grade is produced by a low-pressure suspension polymerization process, which provides a controlled molecular weight distribution and a density of 0.944 g/cm³ measured under ISO 1183-1:2019. The melt flow rate is 0.30 g/10 min at 190 °C/2.16 kg according to ISO 1133-1:2022. These values place the material in the low-flow, high-melt-strength region used for containers with capacities up to 5 L, where parison stability and top-load strength are primary processing requirements. The designation FLP 3714 is not a specification by itself; the lot-specific certificate of analysis defines upper and lower control limits for density and melt flow rate. The material is not intended for thin-wall injection molding because the low melt flow rate limits flow length under normal injection pressures. Published data for this specific configuration is limited; processability claims should be confirmed on the target machine.

How does the molecular architecture of FLP 3714 influence processing behavior?

The melt flow rate of 0.30 g/10 min under ISO 1133-1:2022 indicates a molecular weight high enough to resist parison sag during extrusion blow molding, but the value alone does not define the complete rheological response. The ratio of melt flow rates under 2.16 kg and 5.0 kg loads is used to assess shear sensitivity; a melt-flow ratio in the range of 3.0–4.0 is typical for this class of high-density polyethylene. A lower ratio may require a higher melt temperature to maintain output, which reduces the safety margin to oxidative degradation. The recommended melt temperature window is 190–220 °C, and the upper processing limit at the die exit is 230 °C. Above 230 °C, the antioxidant package is consumed rapidly, forming gel particles that accumulate on the die lip and produce parison surface defects. The density of 0.944 g/cm³ reflects a crystallinity level that balances stiffness against environmental stress-cracking resistance; increasing density in the same product family may improve top load but may shorten failure time under ASTM D1693-15 condition B. The Vicat softening point of 128 °C under ISO 306:2022/A50 does not imply continuous load-bearing capability at that temperature; designs above 60 °C require creep and stress-relaxation verification.

Parison formation on shuttle machines equipped with 60 mm/24:1 L/D single-screw extruders is typically carried out at die temperatures of 190–210 °C and melt pressures of 15–25 MPa. A barrier screw with a Maddock mixing section and a screen pack of 60/80/100 mesh is used to homogenize melt temperature and filter gel particles. Screw speeds above 80 rpm can widen the residence time distribution and cause localized thermal degradation in the compression zone; this degradation is usually visible as yellowing or gel specks in the bottle wall. Mold temperatures of 10–30 °C are specified to control cooling cycle time and reduce post-mold shrinkage in containers between 1 L and 5 L. Regrind addition up to 20% by weight is common on production lines, but the regrind must be free of polypropylene closures, paper labels, and PVC contamination. Mixed-polymer contamination lowers stress-crack resistance under ASTM D1693-15 condition B and can create delamination at the pinch-off weld. Blow-up ratio is typically 2.0–2.5:1; higher ratios reduce top-load strength because the wall thickness distribution becomes less uniform. Parison programming with 20–50 points is used to control wall thickness at the bottle shoulder and base. Die swell is lower than that of high-molecular-weight HDPE, which permits a narrower die gap adjustment and reduces flash at the pinch-off. The parison hang time should not exceed 3 seconds for wall sections below 1.0 mm; longer hang times require a higher-molecular-weight HDPE grade or a reduced melt temperature. Output rate is limited by the low melt flow rate rather than screw torque in most machines, but extruders with deep feed sections and 24:1 L/D or greater provide stable conveyance at melt pressures above 20 MPa.

Thermocouple drift and shear heating create a narrow process window that must be controlled in production. The difference between set-point and actual melt temperature can reach 5–8 °C depending on screw speed, back pressure, and barrel conditioning. Because the upper melt temperature limit of 230 °C is close to the recommended processing band, temperature controllers should be calibrated to ±2 °C or less. When the melt temperature exceeds 225 °C at the screw tip, thermo-oxidative chain scission accelerates; gels form in the die and appear as shark-skin or melt fracture patterns on the parison surface. Reducing screw speed from 80 rpm to 50 rpm typically lowers melt temperature by 8–10 °C in a 60 mm extruder, restoring the material to the stable window. A vented barrel is not recommended for this grade because the vent can introduce pressure fluctuations that destabilize the parison. The material is not hygroscopic, but condensed surface moisture on cold pellets can produce steam pores in thick sections; drying at 80 °C for 2 hours is used only when visible surface water or frost is present.

Sheet extrusion with FLP 3714 is less common than blow molding but is technically possible on a 90 mm/30:1 L/D single-screw extruder with a flat die and polished chill rolls. Melt temperatures of 200–220 °C are used to control draw sag and web tension. Chill roll temperatures of 20–40 °C control surface finish and crystallinity; a lower roll temperature freezes gloss but increases internal stress. Sheet gauges below 0.5 mm may require a higher melt flow rate because the web loses tension when melt strength is too high. In thermoforming, the sheet must be heated to 160–180 °C for uniform drawing; heating above the Vicat softening point of 128 °C is required. The sheet may be used for dunnage, trays, or secondary packaging where transparency is not required. Published data for this specific configuration is limited; processors should request a sheet extrusion trial from the supplier before specifying the grade for a sheet line.

Which application conditions expose the grade’s critical limitations?

The grade’s low melt flow rate becomes a limitation when the container design includes very thin wall sections below 0.6 mm or long flow paths in handle regions. At melt temperatures below 190 °C, melt viscosity rises and the parison may exhibit poor die swell, causing pinch-off weld weakness. At melt temperatures above 220 °C, the low melt strength no longer supports the parison and the container wall thickness becomes erratic. The usable processing window is therefore 190–220 °C, and in some machines with high shear heating the practical window narrows to ±5 °C around the set point. Containers with sharp corners and deep ribs may require a higher-flow grade or a design change because the material cannot be post-formed under pressure in blow molding. In chemical packaging, continuous exposure to aggressive solvents or strong oxidizing agents above 40 °C can reduce stress-cracking life; a higher-molecular-weight or crosslinked polyethylene may be required. Published data for this specific configuration is limited; the user must test the finished container with the actual chemical formulation.

Specification, regulatory status, and test-standard matrix

Food-contact suitability in the United States is assessed under FDA 21 CFR 177.1520 for olefin polymers, provided the finished article meets the extraction limits applicable to the intended food type and temperature. European food-contact compliance is based on Regulation (EU) No 10/2011; the overall migration limit is 10 mg/dm² of food contact surface, and specific migration limits for monomers and additives must be verified on the final article. The grade is not supplied as a medical-grade resin unless a separate medical change notification is issued. The following values are representative data from manufacturer documentation and are not an independent product specification.

Environmental stress-cracking resistance is evaluated under ASTM D1693-15 condition B; published data for this specific configuration is limited, and the test is sensitive to thickness, internal stress, and wetting agent concentration. Processors should not use a single ESCR value for product design. Tensile elongation values and melt-flow ratio should be requested from the supplier certificate of analysis for each lot. The certificate should also report the antioxidant level or stabilizer package batch code so that regrind accumulation can be tracked on the production floor.

When FLP 3714 replaces injection-molding HDPE in blow-molded containers

A shift from an injection-molding HDPE with an MFR of 4–20 g/10 min to FLP 3714 changes both machine settings and part performance. The lower MFR raises melt viscosity and parison hang strength, but it reduces the ability to fill thin ribs, threads, or handles under injection pressures below 100 MPa. Injection-molding grades are not suitable for continuous parison extrusion because they sag and produce uneven wall thickness; FLP 3714 is formulated for the low-flow, high-shear regime of blow molding. Compared with large-part blow-molding HDPE grades with MFR values near 0.1–0.2 g/10 min, FLP 3714 flows more readily at the same melt temperature, lowering extruder torque and die head pressure. This can improve surface finish but reduces the maximum parison length before sag. Compared with high-density polyethylene film grades, FLP 3714 is formulated for thicker cross sections and slower crystallization kinetics; the additive package is selected for repeated extrusion heat rather than high film line-speed oxidation demands. The exact additive package is proprietary; published data for this specific configuration is limited. Processors should perform a comparative trial on the target mold before substituting grades, with wall thickness distribution measured by non-contact thickness gauge and top-load deformation by a compression tester.

Incoming quality control for FLP 3714 should include melt flow rate measurement under ISO 1133-1:2022, density by gradient column or gas pycnometer under ISO 1183-1:2019, and visual inspection for contamination. The melt-flow ratio between 2.16 kg and 5.0 kg loads is a more sensitive indicator of molecular architecture than single-point MFR; a change greater than 0.5 units between lots may indicate a shift in molecular weight distribution and should trigger a mold trial before production. Spectroscopic methods such as Fourier-transform infrared spectroscopy are used to confirm the absence of polypropylene contamination in regrind; methyl-group absorbance peaks can indicate mixed polymer. Batch-to-batch color variation is controlled by the supplier, but processors should measure yellowness index under ASTM E313-20 if the container is used in unpigmented applications. The use of masterbatch at levels above 3% by weight may shift melt viscosity and die swell; the masterbatch carrier resin must be compatible with HDPE.

Storage conditions affect the subsequent processing window. The pellets should be kept in a clean, dry area below 60 °C and shielded from ultraviolet exposure to reduce oxidative degradation at the pellet surface. Water pickup is generally not significant for HDPE unless the pellets are stored outdoors in high humidity; condensation on cold pellets can cause surface defects, and drying at 80 °C for 2 hours is applied only when visible surface water or frost is present. The grade should not be combined with copper-based antioxidants or amine-based additives unless the supplier has disclosed compatibility with the stabilizer package; additive incompatibility can alter long-term thermal oxidative stability and produce color shifts in the finished article. After prolonged storage, the quality control laboratory should re-test melt flow rate under ISO 1133-1:2022 and density under ISO 1183-1:2019 before the lot is released to production. The supplier’s recommended storage period should be confirmed on the certificate of analysis rather than assumed from generic HDPE data.