LyondellBasell HDPE 2723PM is a high-density polyethylene resin identified by the alphanumeric grade designation 2723PM within the manufacturer’s high-density portfolio. The product is supplied as a pelletized thermoplastic for extrusion or injection molding, with lot-specific properties certified on the supplier’s certificate of analysis. The grade is differentiated from general-purpose HDPE by its molecular weight distribution, melt viscosity, and additive package, which together set the processing temperature window and end-use mechanical response. Because the supplier’s technical data sheet is the controlling document, the following sections identify specification methods and class-typical boundaries rather than substituting lot-specific numerical values.

What specification test methods govern the HDPE 2723PM data sheet?

Melt mass-flow rate is reported under ISO 1133-1:2022 at 190 °C and 2.16 kg load. Density is reported under ISO 1183-1:2019. Tensile properties are determined according to ISO 527-2:2012 using type 1A or type 5A test specimens, and flexural modulus is measured according to ISO 178:2019. Notched impact values may be reported under ISO 179-1:2010 or ASTM D256-23. For high-density polyethylene, density normally falls between 0.941 g/cm³ and 0.965 g/cm³; melt flow rate ranges from below 0.2 g/10 min for high-molecular-weight blow molding and pipe grades to above 50 g/10 min for thin-wall injection molding. The 2723PM designation must be checked against the supplier’s current bulletin for the single-point value and lot-to-lot tolerance. Published data for this specific configuration outside the supplier’s certificate of analysis is limited, and the use of class-typical ranges for machine acceptance or product release is not appropriate.

Extrusion and injection molding response across the 190–230 °C barrel profile

Single-screw extrusion of high-density polyethylene grades such as 2723PM commonly employs a screw length-to-diameter ratio of 24:1 to 30:1, with a compression ratio of 2.5:1 to 3.5:1. Barrel temperatures are maintained between 180 °C and 230 °C, and die-head temperatures are held between 190 °C and 220 °C. Melt temperatures above 260 °C are outside the recommended processing window for standard HDPE stabilizer systems and may accelerate chain scission or oxidative degradation. In contrast to polypropylene, high-density polyethylene does not exhibit the same oxidative sensitivity at standard barrel residence times, but prolonged hold-up in stagnant zones can generate gel particles and black specks. Moisture content below 0.05 wt% is normally sufficient for pelletized HDPE; if storage occurs at relative humidity above 60%, surface condensation should be removed by drying at 60–80 °C for 2–4 h in a desiccant dryer. Production-scale behavior on twin-screw compounding equipment varies with screw configuration and downstream pelletizing load; grade-specific torque and melt-pressure data should be obtained from the supplier or from a line trial.

In injection molding, clamp force requirements follow the projected area and flow length of the cavity, not the grade designation alone. HDPE 2723PM should be evaluated for melt residence time, screw-back pressure, and injection velocity against the supplier’s recommended range. Low-melt-flow HDPE grades require extended pack pressure and hold time to control sink marks and dimensional variation, whereas high-melt-flow grades may exhibit lower melt strength and may require adjusted gate freeze time. Screw decompression before plasticating can reduce drool from vertical nozzle configurations. On production lines with hot-runner systems, gate temperature uniformity and heater calibration strongly influence shot-to-shot variance.

When HDPE 2723PM replaces a fractional-MFI HDPE in closure and container applications

The substitution direction depends on whether the supplier-reported melt mass-flow rate of 2723PM is higher or lower than the incumbent grade; process engineers should compare values obtained under ISO 1133-1:2022. If the melt flow rate is higher, injection pressures may decrease and cycle time may shorten, but environmental stress crack resistance may be lower than that of a fractional-MFI grade. If the melt flow rate is lower, impact resistance and stress crack resistance may improve at the expense of higher melt viscosity and higher pressure drop. HDPE 2723PM should not be treated as interchangeable with bimodal pipe grades rated under ISO 9080 or with linear low-density polyethylene film grades unless the supplier has issued a written statement covering the intended end-use. Compared with linear low-density polyethylene, high-density polyethylene generally exhibits higher flexural modulus and lower puncture resistance; compared with high-molecular-weight blow molding HDPE, an injection molding grade typically has a narrower molecular weight distribution and lower melt strength.

In rigid packaging applications, HDPE 2723PM may be evaluated against general-purpose injection molding HDPE grades using tensile yield stress, flexural modulus, and notched Charpy impact values. The relevant test methods are ISO 527-2:2012, ISO 178:2019, and ISO 179-1:2010. Dimensional stability after demolding is influenced by crystallization kinetics and mold temperature; for high-density polyethylene, mold temperatures between 20 °C and 60 °C are commonly used. Higher mold temperatures increase shrinkage uniformity but extend cycle time. The grade-specific shrinkage coefficient must be taken from the supplier’s technical data sheet and verified on the production tool.

The above table is a class-typical comparison and does not assign a specific processing classification to HDPE 2723PM. Grade-specific placement within these classes must be verified against the supplier’s current technical data sheet and certificate of analysis. Melt flow rate alone does not capture molecular weight distribution, branching, or additive effects that control processing behavior.

Compliance test methods and regulatory certification pathways

For food-contact evaluation in the United States, high-density polyethylene grades may be assessed under FDA 21 CFR 177.1520, which covers olefin polymers intended for use in contact with food. Compliance is ingredient-level and requires end-use migration testing or an appropriate written assumption. For the European Union, plastics intended for food contact are evaluated under Regulation (EU) No 10/2011, with overall migration limits and specific migration limits determined by food simulant testing. REACH registration under Regulation (EC) No 1907/2006 must be confirmed for the European Economic Area. RoHS Directive 2011/65/EU restricts lead, mercury, cadmium, hexavalent chromium, and certain brominated flame retardants in electrical and electronic equipment; unfilled high-density polyethylene grades typically fall below these limits, but a supplier declaration is required for each production lot.

Storage conditions before processing affect the surface moisture and stabilizer integrity of high-density polyethylene resin. The product should be stored in a dry area away from direct ultraviolet exposure. If silo residence time exceeds the supplier’s recommended maximum, the oxidation induction time should be checked by differential scanning calorimetry under ISO 11357-6:2018. Incompatibility with halogenated flame retardants, strong oxidizers, and certain metal deactivators should be evaluated before compounding. Regrind addition above 30 wt% may shift melt flow rate and impact resistance; any regrind ratio should be validated against the supplier’s process window and the final part specification.

On a production line for rigid containers, HDPE 2723PM may be evaluated by short-shot studies and gate freeze tests using the production mold. Cavity pressure sensors should be placed near the gate and at the end of flow to compare holding-pressure requirements against a qualified reference grade. If the material exhibits higher melt viscosity than the incumbent, the hydraulic pressure required to fill the cavity increases, and the process window narrows. If the material exhibits lower melt viscosity, flash, drool, and dimensional variation may appear under the same machine settings. Transfer position, holding time, and cooling time must be adjusted independently rather than copied from a different product.

For extrusion applications, melt pressure before the screen pack and head pressure are recorded at constant feed rate and screw speed. A change in pressure drop over time can indicate gel accumulation or filler agglomeration. When HDPE 2723PM is run on a grooved-feed extruder, the feed-zone temperature should be maintained below the onset of pellet surface melting to avoid bridging in the hopper. For smooth-bore extruders, barrel temperatures should be profiled from a lower feed-zone setting to a higher metering-zone setting. The die land length and drawdown ratio affect melt fracture and dimensional stability; grade-specific recommendations should be confirmed by a trial on the production line.

Comparative evaluation against other products requires the use of identical test methods and specimen preparation. Injection-molded plaques must be conditioned at 23 °C and 50% relative humidity for a defined period before mechanical testing. Density values should not be compared across different sample preparation methods, because cooling rate influences crystallinity. Melt flow rate should not be used to predict molecular weight distribution unless the supplier provides a curve or supporting size-exclusion chromatography data. HDPE 2723PM may differ from other LyondellBasell HDPE grades in additive package, molecular weight distribution, and comonomer content; those differences are not visible from density and melt flow rate alone.

In a closure application, the torque-retention and sealing performance of HDPE 2723PM depend on the cap design, liner, and bottle finish rather than on the resin alone. Short-term mechanical properties cannot predict long-term stress crack resistance under load. Environmental stress crack resistance should be evaluated according to ASTM D1693 or an equivalent notched constant tensile load method if the application involves contact with surfactants, oils, or strong alkaline solutions. For containers holding aggressive fluids, the use of a qualified stress crack resistant high-density polyethylene grade may be required, and HDPE 2723PM should be evaluated against the specific fluid at the storage temperature.

Injection molding trials on machines with clamp force capacities between 800 kN and 6,000 kN are commonly used for HDPE packaging components, depending on cavity number and part area. The screw diameter should be matched to shot weight so that the shot size is between 30% and 80% of the barrel capacity. The cushion should be maintained constant to ensure consistent melt delivery. Screw speeds below 0.2 m/s typical for HDPE reduce shear heating, but the specific limit depends on screw design and melt flow rate. Gate and runner dimensions should follow the supplier’s flow length and wall thickness guidance.

In blow molding applications, HDPE 2723PM may be evaluated for bottle drop impact, top-load strength, and environmental stress crack resistance. These properties are influenced by die swell, parison sag, and mold temperature. A high-density polyethylene grade with insufficient melt strength will show excessive parison sag, leading to wall thinning in the pinch-off and base areas. A grade with excessive melt strength may not trim cleanly or may retain die lines. Comparative evaluations should include unfilled formulations without regrind to isolate resin effects from process effects.

In sheet extrusion and thermoforming, HDPE 2723PM may exhibit drawdown and sag behavior that differ from fractional-MFI pipe or blow molding grades. The melt strength measured on the production line is influenced by melt temperature, die gap, air gap, and draw ratio. Thermoforming windows should be mapped by surface temperature, not by oven setpoint alone, because sheet thickness and color affect heat transfer. If the formed part shows excessive warpage after trimming, the cooling rate and mold temperature should be verified before assigning the variation to the resin.

When compared with filled polypropylene grades, unfilled high-density polyethylene has lower continuous use temperature and lower modulus but may offer improved impact at low temperature and better moisture barrier performance in packaging. When compared with linear low-density polyethylene, high-density polyethylene offers higher stiffness and a sharper melting peak, but lower tensile elongation at break and higher susceptibility to stress cracking in some detergent and surfactant formulations. The selection of HDPE 2723PM over a fractional-MFI blow molding grade should be based on processability, end-use mechanical requirements, and the supplier’s compliance documentation.