LyondellBasell Icorene 3560 BWN 8412 is a linear low-density polyethylene powder grade supplied for rotational moulding, compounding, and selected extrusion processes. The numerical designation identifies the resin within the Icorene polyolefin powder portfolio; the BWN 8412 suffix denotes the natural colour, additive package, and packaging configuration. As an LLDPE, the material is produced by low-pressure polymerisation with a linear backbone and controlled short-chain branching. Typical datasheet values include a melt flow rate of 3.5 g/10 min at 190 °C under 2.16 kg load using ASTM D1238 or ISO 1133-1:2022, and a density of 0.935 g/cm³ at 23 °C using ISO 1183-1:2019 or ASTM D1505. The density positions the product between conventional film-grade LLDPE at approximately 0.918 g/cm³ and high-density polyethylene rotational moulding grades at 0.940–0.944 g/cm³. Primary end uses include rotomoulded tanks, hoppers, containers, fenders, and components requiring a combination of rigidity, low-temperature impact strength, and environmental stress-crack resistance.

The BWN 8412 designation is a commercial coding for colour, additive package, and packaging format. The product is supplied in flowable powder form, typically in bulk packaging with nominal mass in the range of 500–1000 kg per container depending on regional logistics. Because the grade is a powder, it is suitable for dry blending with pigments, antistatic agents, and UV stabilizers prior to charging; dispersion uniformity depends on particle-size compatibility and adhesion between additive particles and the resin powder. For colour-critical parts, a melt-compounded masterbatch or pre-coloured rotomoulding powder should be evaluated, because dry-blended pigments can segregate during charging and lead to colour streaks.

What Distinguishes Icorene 3560 BWN 8412 from Conventional LLDPE and HDPE Grades?

The differentiation is governed by density, melt flow rate, and powder morphology. A melt flow rate of 3.5 g/10 min is lower than injection-moulding LLDPE grades in the 20–50 g/10 min range, providing the melt strength required for rotational moulding wall formation. In comparison with a 0.918 g/cm³ film-grade LLDPE, the 0.935 g/cm³ density increases flexural modulus and yield stress while slightly reducing impact and tear toughness. Against a conventional HDPE rotational moulding powder of 0.942 g/cm³ density, this grade exhibits lower crystallinity, lower Vicat softening temperature, and lower tensile yield stress, but greater environmental stress-crack resistance and a lower brittle-ductile transition temperature. The comonomer type and short-chain branch distribution are not fully detailed in the manufacturer’s published data; published data for this specific configuration is limited. Industrial LLDPE resins in this density band are commonly based on butene, hexene, or octene comonomers. Hexene- and octene-based resins generally produce higher tie-molecule density than butene-based materials of equivalent melt index and density, which can improve dart impact and slow crack growth resistance; however, the converter should confirm the exact comonomer basis with the manufacturer.

Datasheet values for mechanical and thermal performance are generally obtained from compression-moulded specimens, not from rotomoulded walls; therefore, part validation must include testing on prototypes cut from actual mouldings. Tensile property data generated according to ISO 527-2:2012 indicate a yield stress of approximately 14 MPa and elongation at break exceeding 800 %. Flexural modulus measured by ISO 178:2019 is approximately 450 MPa. The Vicat softening temperature under a 10 N load using method A50 of ISO 306:2022 is approximately 115 °C. Low-temperature impact performance is commonly evaluated by brittleness temperature according to ASTM D746; the product is reported below -70 °C. Environmental stress-crack resistance under 100 % Igepal CO-630 at 50 °C using ASTM D1693 condition B typically exceeds 1000 h without failure. Table 1 lists the typical profile for initial material screening. These values are not specification limits and can vary with lot and test laboratory.

Oscillatory rheology of LLDPE with this melt index typically shows a complex viscosity at 190 °C and angular frequency 10 rad/s in the range of 500–1500 Pa·s; the exact value for this grade should be taken from manufacturer lot data. Capillary viscosity measurements by ISO 11443 can support die design for compounding lines. Differential scanning calorimetry by ISO 11357-3 usually shows a peak melting endotherm near 124 °C and crystallisation exotherm near 105 °C for LLDPE of 0.935 g/cm³ density. These thermal signatures are important for designing oven heating curves and cooling profiles. If melt compounding into pellet form is required, a co-rotating twin-screw extruder with L/D 40:1 or higher and screw temperature profile from 180 °C to 230 °C is commonly used. Injection moulding of thin-wall parts from powder is not recommended without prior melt-compounding into pellets because the powder feed can produce shot-to-shot density variation and poor screw conveying.

Rotational Moulding Process Parameters and Powder Handling Limits

Powder handling is a critical production variable because the dry-flow characteristics of the pulverised resin determine mould charging consistency. Dry-flow time measured by ASTM D1895 Method A is typically in the range of 25–35 s/100 g for rotomoulding powders of this melt flow rate. The particle-size distribution is normally controlled with a 35 mesh (500 µm) top size and a controlled fines fraction below 105 µm; excessive fines increase bulk density but reduce dry flow and can produce frothy inner surfaces. Bulk density of the powder is commonly between 0.35 g/cm³ and 0.45 g/cm³. During the heating stage, the powder first tacks to the mould surface, then densifies by sintering as melt surface tension drives void closure. The rate of sintering depends on melt zero-shear viscosity and particle size; smaller particles sinter faster, but excess fines can trap air and create porosity.

On carousel, shuttle, and rock-and-roll rotational moulding machines, biaxial rotation ratios are typically set between 4:1 and 8:1; the actual ratio depends on part geometry and mould mounting. Peak internal air temperature is the primary control parameter. For this LLDPE grade, production-scale equipment commonly operates at 220 °C to 230 °C. The lower bound is critical: when peak internal air temperature falls below 220 °C, particle coalescence may be incomplete, producing pinholes and localised low-impact weld lines. The upper bound is equally important: sustained temperatures above 240 °C accelerate thermo-oxidative degradation, increase discolouration, and reduce impact resistance. Oven air temperatures are often set between 280 °C and 320 °C; higher air temperature reduces cycle time but increases thermal gradient risk. For wall sections of 3–6 mm, oven residence times of 18–25 min are common, but these values must be adjusted for oven air temperature, mould thermal mass, and charge weight. Cooling rate influences crystallite size, shrinkage, and warpage; forced-air cooling followed by controlled water mist reduces cycle time but can increase internal stress in thick sections. The powder should be stored below 50 °C and protected from direct sunlight. Pre-drying is generally unnecessary at relative humidity below 60 %; above that threshold, surface moisture can create steam-induced porosity in thick-walled mouldings.

When Lower Peak Internal Air Temperature Is Required in Moulding

When a lower peak internal air temperature is specified to protect foam-blowing agents, multi-layer constructions, or heat-sensitive inserts, the processing latitude changes. The 3.5 g/10 min melt flow rate of this grade provides greater particle coalescence at lower temperature than a 1.0 g/10 min high-viscosity LLDPE rotomoulding powder, but less melt strength than a 0.5 g/10 min grade. The material will fill shallow rib sections and embossed surface detail more readily, but it may produce more wall-thickness variation in deep-draw or high-surface-area parts. If peak internal air temperature must remain below 210 °C, the operator should compensate with longer oven residence, reduced charge size, or pre-compacted powder; however, incomplete fusion at the inner surface is a known risk. Production experience on carousel machines indicates that wall-thickness variation increases when cavity surface temperature gradients exceed 20 °C across the tool. In multi-layer operations, the inner and outer layers must be selected to avoid premature melting of the grade at the interface; the use of a higher-melting HDPE outer layer can create a thermal gradient that inhibits full sintering of the LLDPE core.

For food-contact and regulated applications, the base olefin polymer is designed for potential compliance with FDA 21 CFR 177.1520(c) and EU Commission Regulation No 10/2011, subject to migration testing and end-use conditions. The grade is supplied without heavy-metal pigments or phthalate plasticizers; however, finished-article compliance must be verified under EU Regulation 1935/2004 Article 3 and applicable national provisions. Under REACH, the polymer itself is exempt from registration, but the monomer and additive inventory must be confirmed according to Title II of Regulation (EC) No 1907/2006. For electrical and electronic equipment, RoHS screening applies to the homogeneous material and requires cadmium below 100 ppm, and lead, mercury, and hexavalent chromium below 1000 ppm unless a specific exemption applies under Directive 2011/65/EU. Table 2 summarises the standards and verification points.

Failure Modes and Operational Boundaries in Production-Scale Rotomoulding

Process deviations in rotational moulding with this powder most often present as pinhole formation, cold spots, warpage, and inner-surface roughness. Pinhole defects arise when powder fails to sinter at the lowest-temperature zones of the tool, typically corners of rectangular tanks or the base of open-top containers. Cold spots occur around metal inserts, flanges, and mould support points; the local wall section may appear acceptable while retaining reduced impact resistance because of incomplete fusion. Warpage results from asymmetric cooling or crystallisation shrinkage differences across the part. The linear low-density structure of Icorene 3560 BWN 8412 has lower mould shrinkage than an HDPE rotomoulding grade of 0.942 g/cm³ density, but demoulding shrinkage still depends on mould temperature, cooling rate, and part geometry. Mould release agents and surface preparation influence demoulding force and should not be assumed to be resin-controlled.

Regrind use should be limited and screened for particle-size distribution; regrind grinding can generate fines that lengthen dry-flow time and reduce bulk density. Moisture absorption above 60 % relative humidity, storage above 50 °C, or contamination with low-molecular-weight lubricants can shift the processing window and generate surface defects. The grade should not be dry-blended with amine-based antistatic agents or other additives that may promote oxidative degradation or surface discoloration at the upper temperature range. Incoming quality control for long-term thermal stability should include oxidative induction time testing by ISO 11357-6 or ASTM D3895. The natural grade does not include a UV stabilizer; outdoor applications requiring extended weathering should use a stabilised grade or dry-blend a compatible UV additive system at the recommended loading. The terminal process boundary is not defined solely by melt flow rate and density; it is set by the interaction of powder dry flow, peak internal air temperature, cooling rate, and part geometry.