LyondellBasell Icorene 3560 BUE 5547 Polyethylene, Linear Low Density is identified in manufacturer technical literature as a high-flow injection-moulding grade within the Icorene polyolefin family. The base resin field 3560 denotes a linear low density polyethylene structure produced by copolymerisation of ethylene with a short-chain α-olefin, while the suffix BUE 5547 denotes a specific additive and version configuration. Manufacturer-published typical values for this grade include a melt mass-flow rate of 35 g/10 min determined at 190 °C under 2.16 kg load according to ISO 1133-1:2022, and a density of 0.934 g/cm³ according to ISO 1183-1:2019. The short-term tensile yield stress is reported as 16.0 MPa and the elongation at break exceeds 800 %, both measured to ISO 527-2:2012. These values position the product as a low-density polyethylene with high flow capability for thin-section injection moulding, not as a film-extrusion, blow-moulding, or rotational-moulding resin.

The term “linear low density polyethylene” in the product description is technically significant. Unlike high-pressure low density polyethylene, the resin possesses controlled comonomer short-chain branching rather than long-chain branching. The resulting molecular architecture provides higher tensile strength, puncture resistance, low-temperature impact resistance, and environmental stress-cracking resistance at a given density, but it also reduces shear thinning and may lower melt strength in processes that depend on parison or bubble stability. For Icorene 3560 BUE 5547, the high melt flow rate further reduces melt strength, making injection moulding of thin-walled parts the primary application envelope.

What distinguishes the BUE 5547 additive package from unstabilised LLDPE grades?

The BUE 5547 suffix in LyondellBasell nomenclature is not part of the base resin structure but identifies a prepared stabiliser and version package. The package typically includes processing stabilisation and ultraviolet stabilisation; however, the exact formulation is proprietary and is not disclosed in standard technical datasheets. The practical consequence is that the grade is supplied ready for applications in which outdoor exposure, long indoor storage, or repeated thermal cycling would otherwise degrade an unstabilised LLDPE too rapidly. Accelerated weathering of finished parts can be conducted according to ISO 4892-2:2013 using xenon-arc irradiation or ISO 4892-3:2016 using fluorescent ultraviolet lamps. Acceptance criteria usually include retained tensile elongation, retained Charpy or instrumented puncture resistance, and visual deterioration. Published data for this exact grade under combined weathering and mechanical loading is limited; therefore, lot- or part-specific validation is required before assigning a service life.

Operationally, a stabilised package such as BUE 5547 does not remove the need for thermal discipline. Melt residence time above 240 °C or multiple regrind passes can consume the process stabilisers, increase yellowness, and generate oxidative gels. For processors using hot-runner systems, the grade should be evaluated for residence-time distribution and dead spots because the high 35 g/10 min flow can mask local overheating until surface defects appear.

Injection Moulding Rheology and Thermal Boundaries

Maintaining a melt temperature below 240 °C is a defined operational boundary for this grade in injection moulding. On reciprocating-screw machines with 20:1 to 24:1 L/D and compression ratios between 2.5:1 and 3.5:1, barrel set points from 180 °C in the feed zone to 220 °C at the nozzle are typical. Mould temperatures are ordinarily maintained between 10 °C and 30 °C to balance crystallisation rate and cycle time. The 35 g/10 min melt flow rate reduces injection pressure and permits filling of wall sections below 1.0 mm, but the processor should not assume unlimited flow length because thin sections freeze quickly at low mould temperature.

Drying is not routinely required. If pellets have been stored in conditions above 60 % relative humidity or have been transported through large dew-point changes, surface moisture can cause splay at the gate; a desiccant dryer set at 60 °C for 1–2 h is often sufficient. Hot-air drying is less effective and can increase surface oxidation if the hopper residence time is excessive. The use of hot-runner systems with manifold temperatures above 240 °C is not recommended for long residence times because stagnation zones can produce acrid odour and yellow streaking. Valve-gated hot runners may be acceptable if the manifold is balanced and the residence time is held below approximately 5 min.

Lot-to-lot variation of approximately ±0.2 g/10 min in melt flow rate and ±0.001 g/cm³ in density can shift fill time, shot mass, and part mass. Injection moulders running thin-wall containers with shot weights below 20 g should monitor first-stage injection velocity, peak cavity pressure, and cushion position rather than melt temperature alone. Because the material is a linear low density polyethylene, it exhibits less shear thinning than a high-pressure LDPE of comparable melt flow; therefore, pressure drop in narrow gates and long flow paths remains more sensitive to melt temperature than to injection speed.

Tensile yield stress of 16.0 MPa to ISO 527-2:2012 places the grade below typical HDPE injection grades and above many flexible LDPE grades. The high elongation at break of more than 800 % is valuable for snap-fit assembly and for impact-loaded parts, but short-term tensile yield is not a design limit for continuous load. For creep-loaded applications, long-term deformation should be evaluated to ISO 899-1:2017 using tensile creep specimens, because LLDPE can exhibit significant creep compliance at ambient temperatures. Unnotched Charpy impact testing to ISO 179-1:2010 frequently produces “no break” results at 23 °C for this density range; therefore, instrumented puncture testing to ISO 6603-2:2023 at -20 °C or below provides a more discriminating measure of ductility. Ribs, bosses, and snap-fit features should be designed with generous radii, because the relatively low flexural modulus of a 0.934 g/cm³ LLDPE requires section increases rather than high-stiffness geometry to carry structural loads.

Weld-line strength in high-flow LLDPE is influenced by melt temperature and mould venting; trapped air at the converging flow front can reduce weld-line impact. Venting grooves of 0.02–0.04 mm depth and avoidance of overpacking are practical measures. If colour masterbatch is added, the let-down ratio should be verified with the stabiliser package; high levels of titanium dioxide pigment can absorb ultraviolet radiation and protect the part surface, but may also raise viscosity and affect weld-line performance.

When Low-Temperature Impact and Outdoor Ageing Are Combined in One Part

For parts such as outdoor bins, agricultural containers, dock fenders, or covers that must survive sub-zero impact after prolonged sunlight, the BUE-stabilised LLDPE system should be validated after weathering, not only on pellets. Xenon-arc exposure to ISO 4892-2:2013 can be followed by instrumented puncture testing to ISO 6603-2:2023 at the specified minimum service temperature. The combination is necessary because UV-stabilised surface layers may remain ductile while the bulk material ages physically; when failure occurs, it may initiate at a weld line, a sharp corner, or a pigment dispersion boundary. Published data for this exact grade under combined weathering and low-temperature impact is limited, so original equipment manufacturers in regulated or high-liability markets typically add end-use tests such as dropping filled containers from defined heights onto concrete at -20 °C.

The high elongation at break of the base resin does not guarantee low-temperature impact resistance after outdoor exposure. In practice, individual manufacturers establish acceptance criteria for retained elongation, colour change, and impact energy. For a linear low density polyethylene of this density range, low-temperature ductility is generally better than for a high-density polyethylene but may be below that of an octene-based metallocene LLDPE. The BUE package narrows the ultraviolet aging gap; it does not eliminate the effect of prolonged heat aging in dark confined service.

Compliance verification for LyondellBasell Icorene 3560 BUE 5547 Polyethylene, Linear Low Density should be based on the current Product Data Sheet, the certificate of analysis for the delivered lot, and regional food-contact requirements. The standards below are commonly referenced in customer specifications for LLDPE injection moulding compounds.

Food-contact compliance under FDA 21 CFR 177.1520 and EU 10/2011 depends on the additive package, migration testing conditions, and the intended food simulant; a grade designation alone does not constitute compliance. The BUE 5547 version must be confirmed against the manufacturer’s regulatory documentation before use in food-contact applications.

Comparative property and processing signals separate this grade from LDPE, HDPE, and metallocene LLDPE

The primary distinction from high-pressure LDPE arises from molecular architecture. At equivalent density, LLDPE provides higher tensile yield, higher puncture resistance, and better environmental stress-cracking resistance, but it displays less shear thinning. In injection moulding, this means the 35 g/10 min grade retains higher viscosity at high shear than a 35 g/10 min LDPE grade, so gate pressure drop may be higher. The distinction from HDPE is dominated by density and crystallinity: the 0.934 g/cm³ material gives lower stiffness but generally better low-temperature impact and stress-crack resistance. Compared with metallocene-catalysed LLDPE, a conventional short-chain-branched LLDPE may have a broader comonomer distribution; this can alter seal initiation, clarity, and toughness, but in thin-wall injection moulding the high flow rate is the controlling economic variable.

Within the Icorene portfolio, lower-flow LLDPE grades supplied for rotational moulding operate at melt flow rates below 10 g/10 min; using a 35 g/10 min grade in rotational moulding would produce thin spots and poor wall distribution. Conversely, film-grade LLDPEs with melt flow rates near 1.0 g/10 min produce high melt strength and controlled bubble stability in blown-film extrusion but are unsuitable for thin-wall injection moulding. The BUE 5547 version is therefore positioned as a specialty within the portfolio: it combines high injection speed, a stabiliser package, and low-density toughness, while sacrificing melt strength and stiffness.