PCC (Iran) HDPE HF5101 is marketed by Petrochemical Commercial Company as a high-density polyethylene resin for blown film and extrusion blow moulding processes. The grade is defined in commercial documentation by a nominal density of 0.951 g/cm³ measured according to ISO 1183-1:2019 and a melt mass-flow rate of 0.10 g/10 min at 190 °C under 2.16 kg according to ISO 1133-1:2022. These two parameters position the material as a high-stiffness, high-melt-strength resin rather than a high-flow injection-moulding grade. The product is therefore specified for applications in which film rigidity, creep resistance and moisture vapour barrier contribute more to package integrity than low-temperature dart impact. The low MFR also distinguishes it from general-purpose blow moulding HDPE grades with MFR values between 0.30 g/10 min and 0.70 g/10 min. Published data for product-specific crystallisation kinetics under quench rates above 50 K/s is limited, so incoming quality control should include density, MFR and ash content before large-scale conversion.

How Do Melt Flow Ratio and Density Position HF5101 Relative to Injection Moulding and Pipe Grades?

The 0.951 g/cm³ density of HF5101 is higher than that of metallocene LLDPE film grades but within the common range for high-stiffness HDPE film resins. The low MFR of 0.10 g/10 min gives the resin a longer terminal relaxation time, higher elongational viscosity and greater melt strength than a 0.70 g/10 min HDPE film grade. These rheological differences reduce parison sag in extrusion blow moulding but increase extruder drive load. Compared with a 0.20–0.50 g/10 min medium-molecular-weight HDPE used for small blow-moulded bottles, HF5101 requires a wider temperature profile or a screw with deeper feed channels to avoid overloading the drive. Compared with injection-moulding HDPE of 8 g/10 min MFR, HF5101 provides better stress-crack resistance and higher notched impact, but it is not suitable for thin-wall injection moulding because the flow length is severely limited. The flow rate ratio under 21.6 kg is not always printed in the grade datasheet; when lot certificates list it, the ratio is a practical check for molecular weight distribution shifts. A higher ratio, commonly above 80, indicates a broader molecular weight distribution and stronger shear thinning, which helps to reduce melt pressure under high screw speeds. Compared with pipe-grade HDPE, HF5101 exhibits lower melt strength but higher flowability; compared with injection-moulding HDPE, it has much lower flowability but better ESCR and tensile stiffness.

In batch-to-batch comparisons, density and MFR are insufficient to predict gel content, die build-up, or bubble stability. The molecular weight distribution can be inferred from extensional rheology and from the 21.6 kg/2.16 kg flow rate ratio. A bimodal HDPE of this density typically uses a low-molecular-weight fraction to improve processability and a high-molecular-weight fraction to retain ESCR at high density. This architecture is the main difference from conventional unimodal HDPE film resins where density increases usually reduce ESCR more rapidly. Table 1 lists representative values from commercial technical literature; lot-specific certificates govern the actual quality.

On a 65 mm grooved-feed single-screw extruder with an L/D of 30:1 and a barrier screw, the processing window for HF5101 begins with barrel temperatures from 180 °C to 210 °C and adaptor/die settings of 205–215 °C. Melt temperature should be held below 230 °C; excursions above this threshold in the presence of oxygen increase gel formation and reduce film tear resistance. Pre-drying is normally omitted for unopened bags stored at relative humidity below 60 %, but surface moisture above 0.05 wt % justifies desiccant drying at 80 °C for 2 h. A starting die gap of 1.0–1.4 mm is typical for monolayer films of 10–50 μm, with a blow-up ratio from 2.5:1 to 4.0:1. The grooved feed section stabilizes output but also raises melt pressure; filter packs with 40/60/100 mesh screen layers should be monitored for pressure drop exceeding 80 bar. Processors should not raise output primarily by increasing rear-zone temperatures because this reduces the solids conveying pressure and can increase surging. Instead, screw speed is raised while maintaining barrel cooling and measuring melt temperature at the screen changer.

For heavy-duty sack film at 80 μm, dual-lip air ring cooling is set with a lower-lip gap of 8–12 mm and internal bubble cooling is introduced above 180 kg/h on a 90 mm die. Frost-line height for 2.5:1 BUR is maintained at 250–400 mm for 10–25 μm film, while the higher stalk configuration used for sacks may position the frost line at 600–900 mm to improve machine-direction tear. Melt temperature at the screen changer should be measured with an immersion probe; if the value exceeds 220 °C, rear-zone temperatures and screw cooling are reduced before further line-speed increases. Flow anomalies such as sharkskin and melt fracture should be mapped on the specific die because onset values depend on die gap, temperature and polymer memory. If sharkskin appears at low take-up speeds, the first response is not a temperature increase but a reduction of the die land length or the use of a wider die gap within the above range. Initial trials for this melt viscosity class often begin at apparent shear rates of 200–400 s⁻¹ in the die lip.

Thermal Stability Limits, Pre-Drying, and Regrind Addition in Multilayer Coextrusion

In multilayer coextrusion with an EVOH barrier layer, HF5101 is brought to the combining adapter at 205–215 °C; higher temperatures increase the risk of thermal transfer to the EVOH stream and accelerate acid-catalysed degradation of the barrier polymer. The grade should be purged with a lower-viscosity LDPE when transitioning from a metallocene LLDPE or a higher-flow HDPE to avoid screw overload and to shorten transition time at the die exit. Clean post-industrial regrind from the same lot may be added at levels up to 20 wt % in non-food-contact layers if the regrind stream is dry and free of paper fibre, strapping and ethylene-vinyl acetate contamination. Regrind for food-contact layers must be qualified under the converter’s migration protocol because thermally aged HDPE can exhibit increased low-molecular-weight extractables. Oxidation induction time of the regrind measured by ISO 11357-6 at 210 °C should not fall below the supplier’s recommended minimum, and repeated extrusion passes should be limited when gel counts exceed the lot-specific action limit. Pre-drying of regrind is required at relative humidity above 60 % or when moisture content exceeds 0.05 wt %. Incompatibility with amine-based antifog concentrates has not been established for this specific grade, but converters should verify additive interactions because amino-functional additives can alter organoleptic performance in sealed food packages.

The melt temperature is measured with a flush probe in the adapter; if the temperature exceeds 220 °C, the screw cooling and rear barrel temperatures are reduced before increasing line speed. For films requiring low gel content, nitrogen blanketing of the hopper and a 20 μm screen pack can reduce oxidative degradation during long campaigns. Published data for gel-count development in this specific resin over multiple re-extrusion passes is limited. In corona-treated film structures, treatment should be applied after the film is cooled below 35 °C; excessive treatment at high line temperatures can raise surface oxidation to a level that reduces seal strength.

When HF5101 Replaces a Lower-Density Unimodal Film Resin in Heavy-Duty Sack Applications

In heavy-duty sack applications with average film thickness of 80 μm, a converter may replace a 0.948 g/cm³ unimodal HDPE with HF5101 to increase secant modulus and creep resistance at equal thickness. Because density is the primary variable controlling stiffness in this range, the higher density of 0.951 g/cm³ raises the film modulus but may reduce dart impact under ASTM D1709A unless blow-up ratio and frost-line height are adjusted. The low MFR of 0.10 g/10 min supports bubble stability at low frost-line heights and permits higher stalk heights, which can improve tear balance. Compared with a 0.70 g/10 min film grade, HF5101 typically requires a higher die pressure and a narrower temperature window, and haul-off speed may be limited by drive torque rather than bubble stability. The change in moisture vapour transmission rate associated with the density increase should be measured by ASTM E96 or ISO 15106-2 rather than extrapolated from another grade.

Compared with a butene LLDPE of density 0.918 g/cm³, HF5101 has higher tensile modulus and lower elongation at break but lower dart impact. In a multilayer film, HF5101 may be used as a stiff core while LLDPE skins provide seal strength. Seal initiation temperature measured by a heat-seal tester is influenced by density; the higher density may require a sealing temperature 5–10 °C higher than a lower-density film. The converter should generate a seal curve per ASTM F88 before setting bag-machine dwell time. Dart impact comparisons against a specific lower-density reference resin are not established by published data, so pilot-scale confirmation at the target gauge is required before committing to full production.

Regulatory documentation for PCC (Iran) HDPE HF5101 is typically based on the base olefin polymer and does not automatically cover pigments, processing aids or masterbatch additives added downstream. The converter remains responsible for the final food-contact article under EU 10/2011 and FDA 21 CFR 177.1520. Table 2 summarises the key compliance parameters that should be verified on lot certificates.

In extrusion blow moulding of 5 L containers with a 200 g shot weight, HF5101 is processed at a melt temperature of 205 °C and a mould temperature of 15–25 °C. The low MFR increases parison sag resistance, but it also increases extruder back pressure. Tooling should provide a die gap of 1.5–2.0 mm for a 5 L container with 2.5–3.0 mm handle pinch-off depth, and the clamp force should be set to the machine manufacturer’s minimum required value rather than the maximum. Weld-line integrity in the pinch-off area is evaluated by sectioning and by burst testing at 1.5 times the nominal service pressure. If the resin is used for a container requiring food-contact approval, migration testing on the finished container takes precedence over pellet compliance certificates because the blow moulding process changes crystallinity and surface-to-volume ratio. For converter operations that run both HF5101 and a high-flow HDPE, the transition procedure should begin with the high-flow HDPE and finish with HF5101 only after the extruder head pressure has stabilised below the safety limit.