Dow ELITE 5940G is a metallocene-catalyzed linear low-density polyethylene resin marketed within the enhanced polyethylene portfolio for blown film conversion. The nominal density is 0.940 g/cm³ when determined according to ASTM D792, and the melt index is 0.85 g/10 min at 190°C under a 2.16 kg load using ASTM D1238. These two values are the primary resin specifications for grade identification. The density places the product at the upper edge of the linear low-density range and the lower edge of medium-density film resins, while the melt index identifies a high-viscosity extrusion product rather than an injection molding or rotomolding grade.

The polymerization route uses a constrained-geometry catalyst system and solution-phase production, which produces a narrow molecular weight distribution and homogeneous incorporation of octene-1 comonomer. The homogeneous short-chain-branch distribution reduces the crystallizable-sequence length distribution relative to Ziegler-Natta butene-based LLDPE, which is often characterized by wider melting-temperature breadth and less uniform branch placement. For film converters, the practical effect is not visible in the resin pellet but appears in seal initiation, optical uniformity, tear balance, and low-molecular-weight extractables.

In terms of solid-state structure, an octene-based mLLDPE at 0.940 g/cm³ may retain higher dart impact and Elmendorf tear than a butene-based LLDPE of equivalent density and melt index because the longer short-chain branches and more regular branch spacing support a higher effective tie-molecule fraction. The result is not recoverable from density and melt index alone and must be validated on the target blown film line.

What Is Covered by the Resin Specification and Test Method Boundaries?

The following table contains the resin-level parameters used for grade selection. Film properties are not specifications; they depend on die configuration, blow-up ratio, frost line height, output rate, and downstream conversion conditions.

Secondary thermal and mechanical data, including DSC melting temperature, Vicat softening point, tensile properties, and film impact values, are published as typical values in the supplier’s current technical data sheet. They are not intended as batch release limits. The melt-flow rate below 1.0 g/10 min indicates that the material is not optimized for thin cast film or injection molding processes requiring low melt viscosity; attempts to use it in such equipment may lead to high melt pressure and melt fracture.

Within the enhanced polyethylene family, the density digit indicates the stiffness segment. Grades at 0.918 g/cm³ or below are typically selected for sealant films, high-clarity film, or stretch applications, while grades near 0.935–0.940 g/cm³ are selected for stiff industrial film. The specific 5940G grade has higher density than many flexible packaging grades, which contributes to modulus but can reduce tear propagation resistance. Product substitution should not be made solely on the basis of melt index without evaluating blown film property balance.

On production-scale blown film towers fitted with grooved-feed extruders of 60–90 mm screw diameter and L/D ratios near 30:1, melt temperatures are commonly maintained between 190°C and 230°C. The narrow molecular weight distribution reduces die swell compared with high-pressure LDPE, so the internal bubble pressure and frost line height require recalibration when switching from an LDPE-rich recipe to a 100% ELITE 5940G formulation. Head pressure is usually lower than that of HDPE film resin at the same output but may be higher than that of a high-melt-flow LLDPE due to the grade’s high molecular weight.

Capillary rheometry is not part of the routine release specification. In process troubleshooting, it is used to compare shear viscosity and shear thinning across candidate resins. The shear viscosity of this grade is typically more Newtonian at low die-lip shear rates than high-pressure LDPE, meaning there is less shear thinning; this is why die-lip shear rate and die gap become primary controls for melt fracture.

Optical haze measured by ASTM D1003 is influenced more by die condition, melt temperature, and cooling air than by the resin in many heavy-gauge industrial structures. High melt temperature oxidation can generate die-lip deposits that increase haze, while slower cooling can increase surface roughness from crystalline microstructure. No special nucleating agents are required for general-purpose opaque films; clear film structures may require a lower-density grade or additional processing adjustments.

Blown Film Die Selection, Melt Fracture Onset, and Bubble Stability Diagnostics

Sharkskin melt fracture is the most commonly reported surface defect when running metallocene LLDPE of this density on spiral mandrel dies. With a die gap of 1.2 mm or less, surface roughness can appear at modest output because the melt relaxes slowly at the die exit and the die-lip shear rate rises rapidly. On a 75 mm grooved-feed extruder running between 180 kg/h and 250 kg/h, stable film surfaces have been obtained by opening the die gap to 1.5–2.5 mm or by adding a fluoropolymer processing aid at 200–500 ppm. The exact critical shear rate for melt fracture is configuration-dependent and is affected by die-surface finish, melt temperature, and conditioning of the die lip; published data for this specific grade across all die geometries is limited.

Bubble stability is the second critical limit. Because the linear architecture has less strain hardening than high-pressure LDPE, the bubble is more susceptible to vertical oscillation, draw resonance, and punctures caused by air turbulence. Stable operation is usually achieved at blow-up ratios of 2.0–3.0 and frost line heights of 3–8 die diameters. A frost line height below 3 die diameters may quench the film before sufficient transverse orientation and crystallization, shifting the tear balance toward machine-direction weakness. A frost line height above 8 die diameters can reduce line speed and increase film gauge variation due to bubble sag. When die-lip air-ring capability is insufficient, blending 10–20 wt% high-pressure LDPE is a practical way to increase melt strength, but it reduces film stiffness and changes dart impact and tear balance.

Post-industrial recycled trim from ELITE 5940G can be re-extruded at up to 20–30 wt% in many heavy-duty film structures without severe loss of film toughness, but the exact allowable regrind fraction depends on the number of heat histories, contamination level, and final dart impact specification. Each heat history increases gel count and reduces tear resistance; converters running high regrind fractions should monitor melt pressure, film defect counts, and retained dart impact.

In relation to Ziegler-Natta butene-based LLDPE of similar melt index, ELITE 5940G generally offers a lower seal initiation temperature, improved optical uniformity, and higher puncture resistance due to the more homogeneous comonomer distribution. Against high-pressure LDPE, it provides higher tensile strength and higher puncture resistance but lower melt strength, smaller die swell, and a narrower die-gap window. Against HDPE film resins, it has lower stiffness and lower maximum continuous-use temperature but substantially higher dart impact and deeper draw. These differences position the resin in heavy-duty sack, industrial liner, and multi-wall packaging where abuse resistance and down-gauging are valued more than built-in bubble stability or thermal resistance.

Coextrusion compatibility with LDPE, LLDPE, HDPE, and tie resins is generally acceptable when the adjacent melt viscosities are reasonably matched. Interfacial flow instabilities can appear when the layer viscosity ratios exceed the stable window of the particular die design; for multi-layer structures containing ELITE 5940G as a core or sub-layer, process adjustments are often required to maintain layer thickness uniformity. Heat-seal settings for the resin are typically lower than for HDPE but higher than for VLDPE grades; the sharp melting distribution gives a relatively narrow seal-transition range, and sealing parameters must be established on the finished package.

When Down-Gauging Below 25 µm Becomes a Critical Design Decision

At thickness below 25 µm, retained film stiffness is a major advantage of the higher density, but tear-propagation resistance can become the limiting property. Dart impact should be measured according to ASTM D1709, Elmendorf tear according to ASTM D1922, and tensile properties according to ASTM D882 on the actual film produced under target line conditions. The higher density of ELITE 5940G may improve secant modulus but reduce the energy-dissipation mechanisms associated with interlaminar cavitation and tie-molecule pulling; therefore, tear strength in the transverse direction can be lower than that of a 0.918 g/cm³ mLLDPE. If the end-use failure mode is tear propagation from punctures, a lower-density resin or a lower-density blend may be more robust. If the failure mode is tensile failure under sustained load, the modulus retention of ELITE 5940G supports down-gauging within the validated range.

Masterbatch letdown ratios of 2–6 wt% are common for color and functional additives. The carrier resin should be selected to avoid excessive viscosity mismatch with the narrow molecular weight distribution of the base resin; otherwise, streaks and visible flow lines can appear at high output. Loadings above 6 wt% of particulate additives, especially titanium dioxide, should trigger re-validation of dart impact and Elmendorf tear because solid particles act as stress concentrators. Slip and antiblock additives are normally added via masterbatch rather than by direct powder addition, which preserves product uniformity and avoids dust exposure.

Food-contact compliance in the United States is evaluated under 21 CFR 177.1520(c) for olefin polymers, subject to the extractables and end-use limitations in the regulation. For the European Union, plastic materials and articles intended for food contact are evaluated under Regulation (EU) No 10/2011, Annex I, including overall migration and specific migration limits. Compliance is not established by the resin grade alone; it requires data on the final formulation, additive package, processing temperatures, and intended food-contact time and temperature. The product carries no inherent antistatic, UV stabilization, flame retardancy, or high oxygen barrier; those properties require additional masterbatches or coextruded barrier layers.

Because polyethylene is hydrophobic, drying is not normally required before extrusion. If pellets have been stored at 85% RH or higher, or moved from cold storage into a warm production hall, surface condensation may form; in that case, a hopper dryer at 60–70°C for 2–4 h is sufficient to remove moisture. The melt should not be held above 280°C for extended periods, and repeated or prolonged hold-up at temperatures above 230°C can produce oxidative gel specks and reduce film appearance. This grade is not intended for continuous service above its melting point, retort or autoclave conditions, or direct contact with aromatic hydrocarbons without barrier protection.