Shandong Yulong HDPE 7000F is a high-molecular-weight high-density polyethylene extrusion grade supplied in pellet form and directed toward blown film conversion. The product is not positioned as a general-purpose injection moulding or pipe resin; the grade suffix denotes film extrusion, and the low melt flow rate is selected to deliver a combination of melt strength, dart impact resistance, and stiffness in thin-gauge film. Manufacturer lot-release data and technical summaries list a nominal density of 0.949 g/cm³ and a melt flow rate of 0.04 g/10 min when measured at 190 °C under a 2.16 kg load using ISO 1133-1:2022. At this flow level, the resin has a higher weight-average molecular weight than typical medium-flow HDPE film grades, which shifts processing behaviour toward elevated melt viscosity and higher die pressure. The resin is applicable to high-strength carrier films, garment bags, industrial liners, and geomembrane feedstocks where gauge reduction below 10 µm is commercially relevant. In food-contact applications, the base olefin polymer may be assessed against 21 CFR 177.1520 and EU No 10/2011; the exact compliance status depends on additive package, downstream conversion, and the finished article.

Specification Limits and Test Methods for Shandong Yulong HDPE 7000F

Batch release values are determined with standardised test methods. The tabulated values are representative technical data, not specification limits for all supply contracts; certificates of analysis provide lot-specific results.

Mechanical test specimens are conditioned for at least 88 h at 23 °C ± 2 °C and 50% ± 5% relative humidity according to ISO 291:2008 before tensile evaluation. Dart impact values are gauge-dependent; the value above is specific to film produced at the converter’s reference thickness, and comparisons across grades require identical gauge and test method. The low melt flow rate value under 2.16 kg is insufficient to describe processability; high-load melt flow rate or melt flow ratio should be obtained from the lot certificate for screw design and throughput calculations.

The density of 0.949 g/cm³ positions the product in the high-density class, but the value should not be used alone to infer stiffness. Crystallinity and modulus are influenced by cooling rate, blow-up ratio, and frost line position. The tensile yield stress of 22 MPa and tensile stress at break of 38 MPa are generated on compression-moulded or specified film specimens; they may not correspond to values measured on blown film at high haul-off speeds.

Molecular weight distribution is not specified in short technical data sheets, but the low MFR and film-grade designation imply a high-molecular-weight tail. For process design, the melt flow ratio obtained from high-load melt flow rate and standard melt flow rate is a more useful control parameter than MFR alone. Comparable high-molecular-weight HDPE film grades exhibit melt flow ratios above 20; values for this specific resin require lot measurement under ISO 1133-1:2022 at 190 °C and 21.6 kg load.

On blown-film lines equipped with single-screw extruders of 25:1 to 30:1 L/D, HDPE 7000F is usually processed with barrel temperatures ramping from 180 °C to 210 °C and die temperature held at 200 °C to 210 °C. Actual set points depend on screw design, screen pack, throughput, and die diameter. Die gaps of 1.2 mm to 1.8 mm and blow-up ratios of 3:1 to 5:1 are practical starting conditions. Because the resin has a low MFR, melt pressure at the adapter, breaker plate, and screen pack is higher than for medium-flow HDPE film grades. Screens of 60 to 120 mesh are common; pressure should be monitored to avoid excessive shear heating. Where sharkskin or surface melt fracture appears at high output, additions of 200 to 600 ppm fluoropolymer processing aid are used in comparable high-molecular-weight HDPE film formulations. The exact concentration depends on shear rate, die design, and the masterbatch carrier system.

At 190 °C and 100 s⁻¹, high-molecular-weight HDPE film grades of this type typically show apparent shear viscosity in the range of 2 × 10³ Pa·s to 5 × 10³ Pa·s; by comparison, a medium-flow HDPE film grade may fall in the range of 1 × 10³ Pa·s to 2 × 10³ Pa·s. These values are based on published capillary rheometry for comparable resins; product-specific data are not always available and should be measured for simulation input.

The resin is hydrophobic and has low water absorption below 0.01% at 23 °C and 50% relative humidity. Pre-drying is not required under normal indoor storage, but surface condensation on cold pellets should be removed with dry air at 40 °C to 50 °C before hopper loading. Excessive moisture on pellet surfaces can produce splay-like defects in the film, although the polymer itself is not hydrolytically degradable.

Residence time above 240 °C should be minimised. Thermo-oxidative degradation can form gel particles, discoloration, and odour; if these appear, the line should be purged with a lower-viscosity HDPE or LLDPE purge compound. Shutdown procedures should reduce barrel temperatures below 180 °C before a prolonged stop to limit polymer degradation in stagnant zones.

What Distinguishes HDPE 7000F from Lower-Molecular-Weight HDPE Film Grades?

Relative to a lower-molecular-weight HDPE film resin with a melt flow rate near 0.5 g/10 min, HDPE 7000F generates higher melt pressure at constant screw speed and die restriction. The elevated viscosity is not simply a processing penalty; it contributes to bubble stability and permits gauge reduction without severe bubble sag. The reported nominal tensile stress at break of 38 MPa and dart impact of 250 g for HDPE 7000F are above typical values of many medium-flow HDPE film grades, where tensile stress at break may lie in the 28 MPa to 34 MPa range and dart impact may fall below 180 g under the same test method. These differences arise from higher weight-average molecular weight and broader molecular weight distribution, which increase chain entanglement and tie-molecule concentration in oriented film.

Compared with LLDPE film resins of 0.918 g/cm³ density, HDPE 7000F provides higher modulus and yield stress but a different balance of tear and puncture behaviour. LLDPE grades commonly exhibit lower stiffness and greater stretch at equivalent thickness, whereas HDPE 7000F is specified for stiffness and moisture vapour transmission resistance. The difference in density between 0.949 g/cm³ and 0.918 g/cm³ alone shifts the crystalline fraction and modulus, but additive and drawing conditions also control final film properties.

This grade is not a direct substitute for medium-flow HDPE in extrusion coating or cast film because the low melt flow rate can limit web orientation and line speed. In injection moulding, the flow path is too restricted for multi-cavity tools, and the product is not recommended for that process. Published data for this specific configuration is limited, so conversion to a new downstream technology should begin with pilot trials rather than relying on technical data sheet values.

If frost line height is raised beyond six die diameters, bubble stability and tear balance change

Frost-line position controls the quench rate and the orientation state of HDPE 7000F blown film. Raising the frost line beyond 6 to 8 die diameters delays quenching, permits additional crystallisation, and can raise film modulus while reducing dart impact and increasing tear anisotropy. The effect is visible in film produced at high blow-up ratios, where a high frost line may create a less stable bubble and alter the balance between machine-direction and transverse-direction tear. Operators commonly reset air ring damper angle and internal bubble cooling exhaust to hold frost-line height below 8 die diameters. If bubble instability occurs under high ambient humidity, reducing melt temperature by 10 °C or increasing internal bubble cooling airflow may restore bubble symmetry. These adjustments are line-specific; published data for this exact resin and equipment combination is limited.

Where regulatory approval is required, compliance documentation for HDPE 7000F depends on the finished article and jurisdiction. In food-contact packaging, the olefin polymer base is assessed under 21 CFR 177.1520 and, in the European Union, under EU No 10/2011. The European regulation sets an overall migration limit of 10 mg/dm² for general food contact and 60 mg/kg for infant food contact, based on the specific simulant testing conditions defined in the regulation. Packaging waste applications should be checked against Directive 94/62/EC, which sets a combined lead, cadmium, mercury, and hexavalent chromium limit of 100 ppm. Under REACH, polyethylene as a polymer is exempt from registration, but imported articles containing substances of very high concern above 0.1% w/w trigger notification and communication obligations under Regulation EC 1907/2006. A converter-specific additive declaration is required because additives, not the base resin, typically determine final food-contact and REACH compliance.

Applications for HDPE 7000F include high-strength carrier bags, garment bags, industrial liners, and geomembrane feedstocks. In geomembrane use, the resin is often combined with carbon black masterbatch and processed into sheets above 0.75 mm; the low MFR contributes to stress-crack resistance in the welded sheet, but weld validation should follow ASTM D6392 or project-specific shear peel protocols. In thin-gauge bag film, gauge control is critical: film thickness variation should be kept below ±5% for consistent dart impact and tear results. Converters producing high-strength bags at 12–18 µm typically use gravimetric dosing and internal bubble cooling. The product is not recommended for injection moulding, rotomoulding, or pipe extrusion without reformulation because the melt flow characteristics do not match these process requirements.