LyondellBasell Icorene 3560 BUE 5917 is classified as a polyethylene, linear low density under ASTM D883 and ISO 472. The base resin is a copolymer of ethylene and an α-olefin; the short-chain branches introduced by comonomer insertion disrupt lamellar crystallization and produce a property balance that differs from long-chain branched low density polyethylene. Distributor technical listings commonly identify the numeric field 3560 with a nominal density of 0.935 g/cm³ when measured by ASTM D792 or ISO 1183-1, and a nominal melt flow rate of 6.0 g/10 min when measured at 190 °C under 2.16 kg load by ASTM D1238. The suffix BUE 5917 is a supplier-specific blue-tinted UV-stabilizer and processing package. Published data for this specific configuration is limited; the controlling specification remains the certificate of analysis and manufacturer technical bulletin.

At a nominal density of 0.935 g/cm³, the material sits near the upper boundary of the LLDPE classification and approaches the medium-density polyethylene range. This density level is frequently selected for rotomoulded parts requiring a balance between stiffness, chemical resistance, and low-temperature ductility. The molecular architecture contains a substantial fraction of linear chain segments between short-chain branches; this produces higher crystallinity than a 0.915 g/cm³ film resin, while the branch distribution suppresses the thick lamellae and rapid crack propagation observed in HDPE homopolymer.

In storage, the resin should remain below 50 °C and out of direct sunlight. Polyethylene of this class is not hygroscopic; pre-drying is not required for virgin powder unless condensation has formed after outdoor storage. Where free moisture is suspected, a desiccant dryer at 60–70 °C for 2–4 h removes surface water without fusing the powder. Reclaimed rotomoulded scrap should be ground, screened through a 250 μm sieve, and blended at no more than 15 wt% with virgin material to limit loss of impact strength and surface finish.

Why Does Comonomer Selection Alter Dart Impact and ESCR in Linear Low Density Polyethylene?

The length and distribution of α-olefin comonomer branches control tie-molecule formation and crystalline morphology. An ethylene/1-octene copolymer with the same density as an ethylene/1-butene copolymer typically has a more homogeneous branch distribution, lower crystallite lamella thickness, and higher dart impact and environmental stress crack resistance. The effect is measurable by ASTM D1709, ASTM D1693, and ISO 22088-4. Product-specific comonomer identity for Icorene 3560 BUE 5917 is not disclosed in the grade code; it must be confirmed from the supplier safety data sheet or technical bulletin.

The values in the table are general class ranges from public polyethylene technical literature; they are not certification values for Icorene 3560 BUE 5917. When a nominal density of 0.935 g/cm³ is used, the expected flexural modulus and tensile yield should fall in the upper end of the LLDPE band, and the ESCR should be verified under the specific chemical environment of the moulded article.

Compared with HDPE of equivalent stiffness, the linear low density polyethylene structure provides higher puncture resistance and a more ductile failure mode. HDPE with density above 0.941 g/cm³ typically exhibits flexural modulus above 900 MPa and Vicat softening above 120 °C, while this LLDPE class at 0.935 g/cm³ generally shows flexural modulus below 550 MPa and Vicat softening below 115 °C. For load-bearing structural parts, the lower modulus requires thicker wall sections than HDPE; for low-temperature impact and chemical crack resistance, the LLDPE choice may reduce brittle failure rates. The product grade should be compared against the end-use design rather than selected on density alone.

Metallocene-catalysed LLDPE grades with identical density and melt flow rate often show a narrower short-chain branching distribution by temperature-rising elution fractionation. This narrow distribution lowers seal initiation temperature in film and improves organoleptics, but it may reduce melt strength and require tighter temperature control in rotational moulding. Conventional Ziegler-Natta LLDPE grades tend to have broader composition distribution and may tolerate a wider processing window. Icorene 3560 BUE 5917 is not designated in public product listings as a single-site resin; the polymerization and catalyst package should be confirmed before replacing a metallocene material in an existing process.

On a shuttle-type rotational moulding machine with a double-arm biaxial rotation ratio of 4:1 and an oven set point of 290 °C, a powder with a nominal melt flow rate near 6.0 g/10 min typically reaches an internal air temperature of 180–195 °C in 12–18 min, depending on wall thickness and mould conductivity. Raising the density by 0.002 g/cm³ may shift the peak internal air temperature requirement upward by 3–5 K. The operator should monitor internal air temperature rather than oven temperature alone because the core temperature history determines bubble removal, wall density, and tensile elongation.

When Melt Index and Density Are Held Constant, Processability Still Depends on Molecular Weight Distribution

Molecular weight distribution, commonly expressed as Mw/Mn from gel permeation chromatography, affects shear thinning, melt strength, and die swell. Conventional Ziegler-Natta LLDPE materials of this density often have Mw/Mn in the range 3.5–5.0, whereas single-site grades may fall below 3.0. The broader distribution reduces apparent viscosity at high shear rate, lowers extruder head pressure, and improves melt strength for large-part moulding; the narrower distribution improves impact consistency and low-temperature sealing but can transfer more frictional heat through the screw.

In capillary rheometry under ASTM D3835, the apparent shear viscosity at 100 s⁻¹ and 190 °C for a 0.935 g/cm³ LLDPE with melt flow rate 6.0 g/10 min is commonly in the range 200–400 Pa·s. The entrance pressure loss in a capillary die of length/diameter ratio 30:1 provides an indirect measure of melt elasticity. When the wall shear stress exceeds 0.2 MPa, sharkskin may appear; this threshold is lower for narrow-distribution LLDPE than for branched LDPE.

Injection moulding of this LLDPE class is feasible with a general-purpose screw having an L/D ratio between 20:1 and 24:1 and a compression ratio of 2.5:1 to 3.5:1. A barrel profile of 170 °C feed, 200 °C centre, and 220 °C nozzle is typical. Melt temperature should not remain above 240 °C for extended cycles; this accelerates chain scission and may produce yellowing and a decline in impact strength. For a projected area of 300 cm² at a cavity pressure of 35 MPa, the required clamp force is approximately 105 t. Packing pressure is usually maintained at 60–80% of injection pressure to avoid overpacking and moulded-in stress.

Rotational Moulding Operating Boundaries for LLDPE Powder Grades

Particle size distribution is measured by dry sieving according to ISO 3310-1. Rotational moulding powders typically show at least 95% passing 500 μm and 5–15% retained on 125 μm. Bulk density measured by ASTM D1895 is commonly 0.35–0.50 g/cm³. Powder with excessive fines below 100 μm may segregate in the mould and create low-density regions; powder with excessive coarse particles may require longer oven cycles.

Oven set points should be limited to 260–320 °C. Below 260 °C, sintering is slow and bubble removal may be incomplete; above 320 °C, oxidative degradation accelerates. Internal air temperature should reach 180–200 °C and then trigger cooling. Cooling with forced air at 5–8 K/min to 90 °C, followed by water mist at 10–15 K/min, is used to reduce warpage. Too rapid water quench below 80 °C can introduce internal voids in thick sections.

The BUE 5917 package should be verified by accelerated weathering under ASTM G154 or ISO 4892-2. For outdoor blue-tinted parts, retention of tensile elongation after accelerated weathering is a more meaningful criterion than colour change alone. Class-level experience indicates that stabilized polyethylene may retain more than 50% of initial elongation after 12,000 h of Florida exposure, but product-specific data for this configuration is limited.

Chemical resistance at 23 °C is generally excellent for water, aqueous salt solutions, and many alkalis. Strong oxidizing acids such as concentrated nitric acid and halogens can attack polyethylene, especially at elevated temperatures. The environmental stress crack resistance test under ASTM D1693 uses a nonylphenol ethoxylate solution and is a standard screening method; however, field failures are better predicted by ISO 22088-4 or full-scale container testing because the stress state in rotomoulded corner radii differs from the bent-strip coupon.

Rotational moulded LLDPE parts typically exhibit linear shrinkage in the range 2.5–4.0% depending on wall thickness, cooling rate, and mould release. Thicker sections cool more slowly and may show greater shrinkage. Uneven wall thickness can produce warpage of 1–2 mm on a 500 mm flat wall if cooling is not symmetric. Internal air temperature and cooling curve control are therefore more important than nominal resin properties when dimensional stability is critical.

Melt flow rate is determined under ASTM D1238 at 190 °C with 2.16 kg. Density specimens are conditioned at 23±2 °C and 50±5% relative humidity before measurement by ASTM D792. Tensile testing uses ASTM D638 Type IV specimens cut from moulded parts; specimen location and wall thickness affect the result more than resin variability in rotomoulded parts. Low-temperature impact is assessed by ASTM D256 notched Izod at -40 °C or by ISO 6603-2 multiaxial impact, depending on the failure mode in service.

What Regulatory Documentation Must Be Verified Before Food-Contact or Outdoor Use?

For food-contact use in the United States, the base polyethylene may be evaluated under 21 CFR 177.1520, but the blue colorant and UV stabilizer require a separate Food Contact Substance Notification or FDA authorization. The product code alone is not sufficient for food-contact compliance. In the European Union, a Declaration of Compliance against EU Regulation 10/2011 and its amendments is required, including overall migration testing at 10 mg/dm² for general contact and specific migration limits for the additive package.

For industrial and outdoor applications, REACH registration must be confirmed through the safety data sheet. RoHS restrictions under Directive 2011/65/EU apply only to electrical and electronic equipment, where lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE levels must be below the respective maximum concentration values. For toy or childcare articles, heavy-metal migration limits under EN 71-3 or ASTM F963 may apply to the coloured grade. None of these compliance positions should be assumed from the PE classification alone.

Operational limitations include prolonged melt residence above 240 °C, which accelerates oxidative chain scission and reduces low-temperature impact. The material should be isolated from copper-containing heating elements and strong oxidizing acids at elevated temperatures. Regrind streams should be segregated from PVC, acetal, and halogenated flame retardants; residual contamination can generate acid gases during processing. For tanks or containers holding aggressive fluids, environmental stress crack resistance should be tested under ASTM D1693 Condition B at 50 °C or ISO 22088-4 using the actual chemical at the intended service concentration. Product-specific data for Icorene 3560 BUE 5917 is limited in public technical literature; the final part must be validated under the complete mechanical, thermal, and chemical load of the application.