Supplied as a pelletized extrusion resin, NOVA Chemicals HDPE 2807 is a high-density polyethylene grade specified for extrusion blow moulding, sheet extrusion, and heavy-gauge thermoforming. The grade is identified within the NOVA Chemicals high-density polyethylene portfolio by the numeric designation 2807. The resin has a nominal density of 0.957 g/cm³ as measured by ASTM D1505 or ISO 1183-1:2019, and a melt flow rate of 0.72 g/10 min at 190°C/2.16 kg as measured by ASTM D1238 or ISO 1133-1:2022. The low melt flow rate places the material in the high-molecular-weight HDPE range; this limits thin-wall injection moulding but supports parison formation in extrusion blow moulding and sag resistance in sheet extrusion. Representative room-temperature mechanical properties from the manufacturer’s technical data sheet include tensile yield strength of 26 MPa per ASTM D638-14, tensile elongation at break greater than 600%, flexural modulus of 1,170 MPa per ASTM D790-17, Vicat softening temperature near 128°C per ASTM D1525-17e1, and Shore D hardness of 68 per ASTM D2240. Typical end uses include industrial containers, agricultural chemical tanks, automotive fluid reservoirs, and heavy-gauge material handling components. The grade is not designed for thin-wall injection moulding or high-speed packaging films, where melt flow rates above 8 g/10 min are normally required. Table 1 summarizes the primary property values used for incoming material verification.

What Melt Rheology and Molecular Parameters Govern Blow Moulding Suitability?

The melt flow rate of 0.72 g/10 min indicates a high-viscosity, low-shear-flow resin. In extrusion blow moulding, this viscosity level supports parison formation but raises screw torque and head pressure compared with higher-flow HDPE grades. Melt flow rate is a single-point test and does not replace capillary rheometry per ISO 11443. The apparent viscosity of HDPE 2807 under typical blow moulding shear rates of 100–500 s⁻¹ is higher than that of injection moulding grades, and viscosity decreases with increasing shear rate. The degree of shear thinning is controlled by molecular weight distribution and long-chain branching; a broader distribution reduces viscosity at high shear rates more rapidly than a narrow distribution. In blow moulding, die entry temperature is more informative than barrel set point because viscous dissipation in a barrier screw can raise melt temperature by 5–15°C at screw speeds above 60 rpm, depending on extruder L/D and back pressure. Processors running accumulator-head machines should verify that melt temperature at die entry remains below 220°C to minimize parison sag and surface defects. Parison sag measured on an industrial accumulator blow moulder increases measurably when melt temperature exceeds 220°C, producing wall-thickness variation greater than 10% in large containers. Die swell is also influenced by melt temperature and die land length; shorter die lands increase die swell and require parison programming adjustment. These relationships are material- and machine-specific, and published data for this specific configuration in multi-layer coextrusion is limited.

Extruder configuration for HDPE 2807 typically uses a general-purpose single-screw extruder with an L/D ratio from 24:1 to 30:1 and a compression ratio from 2.5:1 to 3.5:1. The feed section should be water-cooled to maintain a temperature below 80°C to prevent premature melting and bridging; the metering section is maintained at 190–210°C. Head pressure below 35 MPa is maintained by screen pack and breaker plate selection. Excessive head pressure increases shear heating and reduces output stability. On continuous shuttle blow moulders, cycle time is controlled primarily by cooling time rather than extrusion rate; increasing melt temperature to increase output often extends cooling time and may reduce part productivity. Process logs show that wall thickness distribution is best optimized through parison programming, not by raising melt temperature. The material should not be purged with low-viscosity polyolefins at high temperatures if molecular weight reduction is to be avoided.

Incoming quality control should include melt flow rate per ISO 1133-1:2022 and density per ISO 1183-1:2019 on each lot, with the supplier certificate of analysis consulted for transition metal residues and stabilizer content.

Thermoforming and Sheet Extrusion Operating Ranges Are Constrained by Sag and Cooling Kinetics

Sheet extrusion with HDPE 2807 is performed on single-screw extruders fitted with a polished roll stack and flexible lip die. The melt temperature for sheet is maintained between 190°C and 230°C; thinner sheet below 2 mm uses the lower portion of the range to maintain melt strength, while sheet above 5 mm may require the upper portion for adequate gauge control. Roll stack temperatures from 60°C to 90°C are used to control sheet crystallinity and surface finish; higher roll temperatures reduce surface marks but increase blocking risk. The high density of 0.957 g/cm³ produces a crystalline morphology with relatively sharp melting near 130°C, so thermoforming requires precise surface heat input. For a 6 mm sheet, the forming window is narrow: surface temperature should reach 165–175°C while the core remains below 150°C. At surface temperatures above 180°C, edge sag becomes measurable and wall thickness distribution deteriorates. At surface temperatures below 160°C, the sheet cannot reproduce mould detail and corner thinning increases. Tool temperatures between 20°C and 60°C provide adequate cooling; aluminium moulds with temperature control channels are used for heavy-gauge parts. The high flexural modulus of 1,170 MPa increases service stiffness but also raises residual stress at sharp corners. Inside radii of at least three times sheet thickness reduce stress concentration and stress whitening. Demoulding is typically performed when core temperature falls below 90°C; attempts to demould at higher temperatures produce warpage due to differential shrinkage across the part. These ranges are drawn from general HDPE sheet processing practice and should be confirmed on the production line because heating uniformity, sheet thickness, and tool design shift the forming window.

Twin-sheet thermoforming of HDPE 2807 requires matched tool temperatures and adequate venting to prevent gas pockets at the weld interface. The low melt flow rate of 0.72 g/10 min supports sheet maintenance during twin-sheet forming; however, the lower flow increases the time required for the material to conform to textured tool surfaces. Vacuum holes with diameters between 0.8 mm and 1.2 mm are used in dense patterns to compensate for high melt viscosity. Published data for twin-sheet forming of this specific grade is limited; converters should conduct pilot trials before committing to production tooling.

In ambient storage conditions below 60% relative humidity, pre-drying is not mandatory for HDPE 2807 when pellets are stored in closed containers. If the resin is exposed to cold storage or high-humidity conditions, condensation on pellet surfaces may produce surface defects in extrudate; desiccant drying at 80°C for 2–4 h is recommended before processing. Prolonged melt residence time above 230°C or repeated reprocessing can cause chain scission, a measurable reduction in melt viscosity, and the formation of gels. The product is not recommended for blending with amine-based processing additives or certain hindered amine light stabilizers without testing, because amine chemistry may interact with residual peroxide or stabilizer components and alter colour or oxidative stability. For outdoor service, an unstabilized HDPE of this density will undergo surface oxidation and embrittlement; a UV-stabilized variant or carbon black addition is required. The base grade is not formulated with an antimicrobial additive, and end-users requiring microbial resistance must qualify an appropriate additive package. The material is not recommended for direct contact with strong oxidizing acids or aromatic hydrocarbons, and chemical compatibility must be verified for each service fluid. Published data for this specific grade in aggressive agricultural chemical contact is limited; ESCR testing per ASTM D1693 on a finished part is required for critical applications.

When HDPE 2807 Is Evaluated Against Lower-Flow and Higher-Flow HDPE Grades

Grade selection within the NOVA Chemicals high-density polyethylene portfolio is driven by melt flow rate, density, and environmental stress crack resistance. HDPE 2807 has a melt flow rate of 0.72 g/10 min, which is at the upper end of the extrusion blow moulding range. Compared with lower-flow blow moulding grades having melt flow rates below 0.40 g/10 min, HDPE 2807 produces lower head pressure and easier purging, but it has lower melt strength and may exhibit greater parison sag at part sizes above 60 L capacity. Compared with injection moulding HDPE grades having melt flow rates from 12 to 20 g/10 min, HDPE 2807 has higher viscosity and is not suitable for multi-cavity thin-wall packaging; injection moulding grades also show lower warpage in thin sections due to faster relaxation of molecular orientation during filling and packing. Compared with bimodal pipe HDPE grades having melt flow rates from 0.20 to 0.50 g/10 min, HDPE 2807 has lower slow-crack-growth resistance but higher stiffness and better processability in blow moulding and sheet. Density is also a differentiating variable: at 0.957 g/cm³, the grade provides higher modulus and lower permeability than lower-density HDPE grades near 0.945 g/cm³, but environmental stress crack resistance generally decreases as density increases. Table 2 summarizes positioning differences among major HDPE categories. Direct substitution of HDPE 2807 for another grade requires verification of melt temperature profiles, mould shrinkage, cooling time, and part performance; the table is not a qualification matrix for a specific tool.

Shrinkage values for HDPE 2807 are governed by part thickness, mould temperature, and crystallinity; typical mould shrinkage in blow moulding is in the 1.5–2.5% range, but published data for this specific grade in injection moulding is limited. For sheet and thermoforming, shrinkage is anisotropic and must be measured on the formed part rather than on an unstressed plaque. The conversion of a tool designed for a lower-density HDPE should account for a reduction in mould shrinkage and an increase in part stiffness when switching to HDPE 2807.

If a converter supplies HDPE 2807 for food-contact articles, compliance with United States requirements is based on FDA 21 CFR 177.1520 for olefin polymers, subject to extraction limitations and end-use conditions. The grade does not automatically confer food-contact compliance because additives and conversion conditions influence the final article. European Union plastics intended for food contact are regulated by Regulation (EU) No 10/2011, with overall migration limits specified in Annex II and specific migration limits for individual substances. REACH Regulation (EC) No 1907/2006 requires the supplier to provide safety data sheet and candidate list information; converters must request lot-specific SVHC declarations when required. RoHS Directive 2011/65/EU applies only if HDPE 2807 is incorporated into electrical and electronic equipment; restricted substances include lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ethers. The base resin is not formulated with intentionally added per- and polyfluoroalkyl substances, but specific PFAS-related specifications require analytical confirmation with the supplier. Recycling and disposal fall under polyethylene streams described by ISO 15270; multi-material labels, adhesives, and fillers reduce recyclability and must be assessed before assigning post-consumer recycling claims. These statements are not a substitute for end-use compliance testing and do not certify the material for medical device or implantable applications.