Lotte Chemical Titan High Density Polyethylene HD5301AA is a high-molecular-weight extrusion blow moulding grade intended for rigid industrial containers, large-volume packaging, and moulded fuel-system components. The polymer sits within the manufacturer’s Titanpro HDPE range and is distinguished from general-purpose blow moulding HDPE by a low melt flow rate, typically 0.30 g/10 min at 190 °C under 2.16 kg load when measured according to ISO 1133-1:2022. Its density of 0.953 g/cm³ under ISO 1183-1:2019 balances stiffness with environmental stress crack resistance. A lower MFR indicates higher average molecular weight and greater chain entanglement, which increases melt strength during parison extrusion but also raises screw torque and head pressure.

The specification profile is conventionally reported on compression-moulded or injection-moulded specimens; the values are typical, not batch-release limits. The tensile stress at yield is approximately 26 MPa under ISO 527-2:2012, elongation at break exceeds 300%, flexural modulus is about 1,100 MPa under ISO 178:2019, and notched Izod impact strength at 23 °C is approximately 20 kJ/m² under ISO 180/A. The Vicat softening temperature is reported near 124 °C under ISO 306 A50 conditions, and environmental stress crack resistance measured as F50 in 100% Igepal CO-630 at 50 °C reaches at least 100 h under ASTM D1693. These properties support applications where stacked-load stiffness, impact resistance at low temperatures, and slow crack growth resistance under chemical exposure are simultaneous requirements.

The following table consolidates typical published properties and the corresponding test designations.

Environmental stress crack resistance in HDPE is not a simple material constant; it depends on comonomer type, short-chain branching distribution, tie-molecule concentration, residual processing stress, and moulded-in orientation. In ASTM D1693, specimens are bent to a controlled strain and immersed in 100% Igepal CO-630 at 50 °C; F50 is the time at which 50% of specimens fail. A resin with higher molecular weight, such as HD5301AA at 0.30 g/10 min MFR, increases tie-molecule density and slows crack propagation. However, the test is statistical and sensitive to surface defects; a value below 100 h can result from moulding flash, scoring, or cooling-induced residual stress rather than bulk polymer deficiency. Lot qualification should therefore pair ESCR with notched Izod impact in ISO 180/A and flexural modulus in ISO 178:2019 to separate surface-initiated fracture from bulk yielding.

Low-temperature impact of HDPE containers is influenced by slow crack growth and notch sensitivity. HD5301AA’s high molecular weight increases impact toughness at −20 °C relative to lower-molecular-weight HDPE, but brittle failure can occur at pinch-off welds if the weld is formed under insufficient melt temperature or premature blow-out. Blow-moulded parts are not isotropic; impact strength in the machine direction commonly exceeds transverse direction, and the difference increases with reduced die swell and high inflation ratios. Published directional impact data for HD5301AA is limited, so drop-test performance should be established on production parts rather than extrapolated from compression-moulded Izod specimens.

Why Does HD5301AA Provide Higher Parison Melt Strength Than Medium-Molecular-Weight HDPE?

Parison stability in extrusion blow moulding is controlled by elongational viscosity and molecular weight distribution. A lower MFR of 0.30 g/10 min corresponds to a higher weight-average molecular weight than a 0.7 g/10 min medium-molecular-weight blow moulding HDPE; the resulting chain entanglement increases zero-shear viscosity and melt strength. The effect is most visible at low shear rates, where sag occurs under gravitational load. Under extrusion shear rates of 100–1,000 s⁻¹, pseudoplasticity reduces apparent viscosity and allows flow through die heads; within the parison, deformation rates after die exit are much lower, so the polymer retains melt strength. This separates HD5301AA from lower-molecular-weight HDPE grades, which may be easier to extrude but require more aggressive parison programming to maintain wall thickness in large mouldings.

The practical difference is measured as parison sag length and weight swell in accumulator-head machines. A high-molecular-weight HDPE with broad molecular weight distribution exhibits higher die swell and weight swell than narrow-MWD grades; tooling dimensions are adjusted accordingly. Published grade-specific die-gap prediction data for HD5301AA is limited, so initial production trials should establish the relationship between die gap, shot size, and part weight at a given head pressure. The use of an extrusion blow moulding machine with a grooved feed throat and L/D 24–30 barrier screw is recommended for consistent plastication, because insufficient melting at high output results in gel particles and surface roughness.

Two process failure modes dominate high-molecular-weight HDPE extrusion blow moulding: melt fracture and parison sag. Melt fracture occurs when wall shear stress exceeds a critical value, producing sharkskin or gross surface roughness at the die exit. With HD5301AA’s high viscosity, die land temperature and die gap must be adjusted; raising the die zone to 200–220 °C lowers viscosity locally, but excessive die heating can create non-uniform parison temperature and wall-thickness variation. Parison sag occurs when the extruded parison stretches under its own weight before mould closing. For a 220 L drum parison weighing approximately 8–10 kg, sag-induced thickness variation can exceed 20% if melt temperature is too high or melt strength is insufficient. HD5301AA is selected specifically to reduce that sag, but it does not eliminate the need for parison programming with axial wall-thickness control.

The melt flow rate is inversely related to average molecular weight, but it does not capture molecular weight distribution or comonomer distribution. High-molecular-weight HDPE blow moulding grades often use chromium or Ziegler-Natta catalysts and may include broad molecular weight distribution to enhance shear thinning. Published catalyst and molecular weight distribution data for HD5301AA is limited; therefore, extrusion behaviour should not be inferred solely from MFR. Apparent viscosity decreases with shear rate more strongly for broad-MWD HDPE than for narrow-MWD grades, which is why the same MFR can behave differently in a low-shear sag condition and a high-shear die flow condition. Production-scale extruders with barrier screws and grooved feed sections are preferred because they deliver higher melt homogeneity at lower melt temperature.

In extrusion blow moulding of containers with capacities from 20 L to 200 L, HD5301AA is typically processed on shuttles or long-stroke accumulator machines with shot capacities exceeding 5 kg. Barrel-zone set points of 180–230 °C and die-zone set points of 190–220 °C are common; selecting the lower end of this range increases melt strength but increases screw torque, while operations above 230 °C risk oxidative chain scission and reduced ESCR. Mould cooling is maintained at 10–30 °C, and blow pressure is typically 0.6–1.0 MPa. The resin does not require predrying for moisture absorption, but if hopper surfaces are cold and ambient relative humidity exceeds 60%, surface condensation can generate splay; a 80 °C hot-air drying step for 2 h is sufficient to remove surface water. Regrind addition up to 30 wt% is commonly practiced when the recycled fraction is free of mixed resin contamination and thermally degraded fines; higher regrind levels may lower ESCR and impact strength, especially in thin-wall areas near pinch-off welds.

The grade is specified for aggressive liquid packaging where slow crack growth and chemical attack create premature failure. These include industrial detergent and surfactant bottles, agricultural chemical containers, oil containers, and large drums for aqueous solvent blends. The ASTM D1693 F50 ESCR test is directly relevant because it applies a constant strain under a surfactant environment; failure time is a statistical median, and the higher-molecular-weight matrix of HD5301AA increases the time to craze propagation. In automotive fuel tank blow moulding, the polymer may be used in multilayer structures with EVOH or polyamide barrier layers; adhesion requires tie-layer resin and published adhesion data for HD5301AA with specific tie-layer grades is limited. End-use fuel permeation performance is governed by wall thickness, fluorination or barrier layer design, and part geometry rather than by the base resin alone.

When HD5301AA Replaces Medium-Molecular-Weight HDPE in Chemical Containers

The substitution is not pressure-neutral. A medium-molecular-weight HDPE with MFR 0.7 g/10 min and density 0.950 g/cm³ typically offers lower melt viscosity, reduced head pressure, and higher screw output, but sacrifices ESCR and melt strength. Conversely, a homopolymer HDPE with density 0.960 g/cm³ and MFR 0.30 g/10 min may increase top-load stiffness but reduces ESCR because the higher crystallinity leaves less amorphous tie-molecule network. HD5301AA occupies an intermediate density region at 0.953 g/cm³; this is selected to balance stiffness at yield with long-term crack resistance. The substitution limit is most visible in tall containers with high fill temperatures, where higher-crystallinity HDPE fails earlier in ESCR despite equal wall thickness.

In injection moulding applications, HD5301AA is generally unsuitable when flow lengths are long and wall sections are below 1.5 mm because its high viscosity increases short-shot risk and injection pressure. The grade is also not intended for film extrusion; blown film HDPE grades typically use lower melt flow and different additive packages. For rotational moulding, the particle morphology and melt flow are not optimised, and published data for HD5301AA in rotational moulding is limited; a rotomoulding-specific HDPE should be selected instead. These boundaries are based on the measured MFR and density rather than supplier marketing classification.

HD5301AA is stabilised for normal blow moulding and storage. It should not be dry-blended with excessive acid-scavenging agents or metal stearates beyond supplier recommendations, because changes in acid scavenger concentration alter colour and may affect organoleptic properties. The grade is not inherently conductive; applications requiring electrostatic discharge protection in solvent containers require an additional conductive layer or surface treatment. Oxidative induction time is not a linear predictor of ESCR; thermal history from processing can reduce both OIT and ESCR if the resin is held above 240 °C for extended periods. Avoid regrind streams contaminated with polypropylene, nylon, or EVOH, since immiscible domains delaminate in the parison and create pinholes in pinch-off zones.

End-use compliance is verified through the following matrix. The base resin datasheet alone does not confer regulatory clearance.

A lot-specific certificate of analysis should be requested for every production campaign, particularly when the moulded part is used with aggressive surfactants, solvents, or food-contact media. Because HD5301AA is a high-molecular-weight blow moulding resin, the processing limits and part thickness distribution are inseparable from the final ESCR and impact performance.