Hanwha TotalEnergies HDPE C911A is a high-density polyethylene copolymer supplied in pellet form for blown film extrusion. Manufacturer technical literature identifies a melt mass-flow rate of 0.15 g/10 min at 190 °C under 2.16 kg load when measured in accordance with ASTM D1238 or ISO 1133-1, together with a nominal density of 0.951 g/cm³ when measured in accordance with ASTM D1505 or ISO 1183-1. These indices place the grade at the high-molecular-weight end of conventional HDPE film resin design space. The material is directed toward heavy-duty sacks, refuse sacks, carrier bags, industrial liners, and high-stiffness blown film where load retention, down-gauging, and bubble stability are operating requirements. Final film properties are not intrinsic resin constants; they are a function of die gap, blow-up ratio, frost-line height, output rate, and blend composition.

Where Does the C911A Molecular Architecture Place It in the HDPE Film-Grade Range?

High molecular weight in polyethylene is indicated inversely by low melt flow rate. At 0.15 g/10 min, the zero-shear viscosity of C911A is higher than that of general-purpose HDPE film resins with melt flow rates in the 0.3–0.5 g/10 min range. The viscosity increase contributes to high melt strength and stable bubble formation on long-stalk blown film lines, but it also increases extruder head pressure and torque demand. The density of 0.951 g/cm³ corresponds to an estimated crystalline fraction of approximately 66–67 % when calculated through the two-phase density model using amorphous and crystalline polyethylene reference densities of 0.853 g/cm³ and 1.000 g/cm³. This crystalline fraction is the structural basis for stiffness and reduced water-vapour transmission rate relative to LLDPE and low-density polyethylene.

The melt rheology of C911A is shear-thinning; apparent viscosity decreases as screw speed and wall shear rate rise. On a single-screw extruder, however, the low melt flow rate means that output per revolution remains limited by feed capacity and motor torque rather than by melting capacity above a certain screw speed. Processing lines intended for this grade should therefore be equipped with high-torque drives and with grooved feed sections capable of maintaining consistent intake at pressures above 80 MPa. The resin should not be treated as a drop-in replacement for an 0.5 g/10 min film grade without auditing the extruder drive, screen changer, and die-head pressure transducers.

On a grooved-feed single-screw extruder with a screw diameter of 65 mm and L/D 30:1, melt temperature set points between 190 °C and 220 °C are used for high-molecular-weight HDPE film grades. For C911A, a barrel profile that ramps from 180 °C near the feed section to 210 °C at the die is a common starting condition, but the actual settings depend on die diameter, air-ring design, internal bubble cooling, and ambient plant conditions. Head pressure must be monitored continuously because the high melt viscosity produces pressure spikes during screen-pack blinding. Die-lip drool and melt fracture are controlled by narrowing the die temperature band and by minimising residence time in the adapter.

A die gap of 1.2 mm to 1.8 mm combined with a blow-up ratio of 3:1 to 5:1 provides a practical processing window for high-stiffness HDPE film. At blow-up ratios below 3:1, the film tends to remain highly machine-direction oriented, increasing machine-direction tear and reducing dart impact. At blow-up ratios above 5:1, bubble instability can appear unless the air ring is optimised and ambient air movement is controlled. Frost-line height is used to adjust film haze, blocking, and impact; a higher frost line generally increases total orientation and can reduce dart impact while improving machine-direction tensile strength. These are process-condition effects that must be characterised on the specific line because air-ring geometry and internal bubble cooling alter the cooling-rate history and therefore the spherulitic and lamellar microstructure of the film.

Polyethylene does not require predrying under normal storage conditions.

Film-Extrusion Torque, Output, and Die-Lip Stability at Low Melt Index

The torque demand associated with C911A is best assessed by recording specific energy input, typically expressed in kW·h/kg. For high-density polyethylene with melt flow rate 0.15 g/10 min, specific energy inputs in film extrusion are commonly higher than those for 0.5 g/10 min grades by 10–25 %, depending on screw design and back pressure. Melt-temperature control should be based on the measured melt temperature at the adapter rather than on barrel set points alone. If the melt temperature exceeds 220 °C for extended periods, oxidation can increase gel count and reduce drop impact; if it remains below 190 °C, surface melt fracture and high torque may limit line speed.

In a typical high-stalk HDPE film operation, the bubble stem length is extended to 1.5–2.5 times the die diameter before radial expansion. This geometry promotes machine-direction orientation and can support down-gauging, but bubble stability in the stem region is sensitive to melt strength and air-ring turbulence. C911A’s high melt strength can tolerate high stalk lengths, provided that the collapsing frame and nip rolls are aligned and that room air currents are blocked by side shields. Process instability at the nip can be triggered by fluctuations in air-ring pressure or by inconsistent film gauge, leading to wrinkles and blocking in finished rolls. These failure modes are observed on production lines when the film bubble is not centred before the frost line and when the collapsing frame angle is too steep for the film modulus at the achieved film temperature.

When the Frost-Line Height Is Raised to Increase Orientation, How Do Tear and Dart Impact Shift?

Blown HDPE film properties are anisotropic. Tensile strength measured according to ISO 527-3 or ASTM D638 typically shows higher machine-direction yield and break strength as frost-line height increases because the polymer chains align along the take-up direction. The same orientation reduces transverse-direction tear resistance. Elmendorf tear data generated according to ASTM D1922 or ISO 6383-2 often show machine-direction tear below transverse-direction tear for HDPE film; process adjustments that increase blow-up ratio and decrease frost-line height shift the balance toward more balanced orientation. Dart impact measured according to ASTM D1709 method A or ISO 7765-1 responds to both orientation and film thickness. If two C911A films of identical 25 µm thickness are produced at different frost-line heights, the lower frost-line film typically retains more low-speed impact because its crystalline lamellae are oriented less in the machine direction and because molecular entanglement is less extended before test deformation.

Down-gauging from 40 µm to 15 µm in C911A-based film reduces mass per unit area but also reduces dart impact and Elmendorf tear in proportion to thickness. A decrease in thickness is not a linear loss for all properties; puncture and dart impact often decline faster than tensile strength because impact processes involve large-strain deformation and crack propagation through the film plane. Therefore, when down-gauging is specified, the processor should evaluate the finished film at the final gauge rather than extrapolating from 25 µm data. For critical applications, melt fracture and gel defects become more important because a small defect is a larger fraction of the thinner cross-section and acts as an initiation point for dart drop or tear failure.

Compared with a general-purpose butene-LLDPE of density 0.918 g/cm³ and MFR 1.0 g/10 min, C911A exhibits higher stiffness and lower water-vapour transmission because the higher density and crystalline fraction reduce the non-crystalline volume available for permeation. The trade-off is lower low-speed puncture and tear resistance in many blown film structures. Blending C911A with 10–30 wt% LLDPE is therefore a standard route when dart impact and heat-seal integrity must be retained; the blend system changes the seal initiation temperature and the hot-tack window and should be re-validated on the converting line. In coextruded structures, C911A is frequently placed in core or stiffness layers while a lower-density seal layer provides sealing performance.

Compared with high-flow HDPE injection-molding grades with MFR above 5 g/10 min, C911A is not suitable for spiral-flow injection because its high melt viscosity prevents filling of thin-wall moulds at practical pressures. Conversely, injection-molding HDPE formulations are not suitable for high-stalk blown film because their lower melt strength produces bubble instability. The specification difference is therefore the primary control: film grades trade high flow for melt strength, and this trade is reflected in screw selection, die design, and downstream tension control.

For food-contact applications, the final article must be evaluated under FDA 21 CFR 177.1520 for olefin polymers, and under the applicable regulatory framework for the intended country. The resin supplier’s conformity declaration, lot certificate, and additive-product list should be reviewed because conversion conditions, coextruded layers, and post-consumer recycle content can alter the regulatory status of the finished package. Under REACH, the resin must be handled according to the safety data sheet; polyethylene in pellet form is not classified as hazardous under normal industrial handling, but dust generated during grinding must be controlled to avoid combustible dust accumulation. These statements are material-class regulatory criteria, not product-specific findings unless confirmed in the manufacturer’s documentation.

Batch-to-batch consistency is monitored through melt flow rate and density, and film-grade HDPE often includes additive packages for thermal stabilisation during extrusion. Incoming QC should include lot-specific verification of melt flow rate and density against the supplier’s certificate of analysis, and film trials should monitor gel count and black specks using inline or offline optical systems. Variations in melt flow rate outside the agreed specification can alter bubble stability and torque; a shift to 0.18 g/10 min may reduce head pressure but can also reduce melt strength and make high-stalk extrusion less stable. Conversely, a shift to 0.12 g/10 min may improve bubble stability but increase torque beyond the extruder’s capacity. Therefore, the operational boundary of C911A is not a single value but a narrow melt-flow and density control window defined by the film line’s drive rating and the required final mechanical balance.