LyondellBasell Icorene 3560 G BWN 8423 is a linear low density polyethylene (LLDPE) supplied as a ground rotational moulding powder. The grade is specified by a melt mass-flow rate of approximately 6.0 g/10 min at 190 °C under a 2.16 kg load in accordance with ISO 1133-1:2022, and by a density of approximately 0.935 g/cm³ determined under ISO 1183-1:2019. The suffix BWN 8423 identifies a colour and stabiliser formulation; the stabiliser package is intended to protect the polymer during the long oven-residence times characteristic of rotational moulding and during outdoor service. Because the product is supplied as powder rather than pellets, particle coalescence occurs directly on the heated mould surface, and sieve distribution, bulk density, and dry-flow behaviour are as technically relevant as melt flow rate.

The typical property envelope for the Icorene 3560 G family includes a tensile yield stress near 18 MPa under ISO 527-2:2012, elongation at break above 800%, flexural modulus near 550 MPa under ISO 178:2019, and environmental stress crack resistance exceeding 1000 h under ASTM D1693 Condition B, 100% Igepal. These values place the grade in the medium-stiffness, high-ductility segment of the rotomoulding polyethylene range. At 23 °C, the tensile yield stress is low enough to permit demoulding from moderate undercuts, while the high elongation at break indicates a ductile failure mode under standard tensile loading. However, notched impact performance at low temperature depends strongly on fusion quality; a badly fused rotomoulded part can show brittle fracture even when the base resin specification is satisfactory.

These values are typical and not batch specification limits. The certificate of analysis for each delivery remains the controlling document for acceptance testing because colour concentrate and stabiliser additions in the BWN 8423 configuration may shift individual values by several percent relative to a natural Icorene 3560 G powder.

Powder Dry-Flow, Particle Size Distribution, and Machine Feeding

Rotational moulding powders fail during mould filling if dry-flow behaviour or particle size distribution is not consistent. Icorene G-series materials are ground to a nominal 35-mesh powder; typical rotomoulding LLDPE distributions have less than 5% retained on a 500 µm screen and a controlled fraction below 125 µm. Published data for the exact sieve curve of the BWN 8423 colour-compounded configuration is limited, so incoming inspection should include sieve analysis to screen for excessive fines. Fines segregation can create resin-rich and resin-lean regions in the mould, leading to local porosity at corners and ribs. Bulk density for LLDPE rotomoulding powders typically falls between 0.33 g/cm³ and 0.38 g/cm³; low bulk density increases the charge volume and can alter the powder-to-mould surface contact pattern.

Because the BWN 8423 package contains pigment and stabiliser, dry-flow may be slightly lower than that of a natural grade due to increased interparticle friction. Processors should measure pourability and angle of repose after lot changes and avoid pneumatic conveying velocities that generate fines by particle attrition. The addition of a mechanical flow additive is not recommended without compatibility testing, because such additives can reduce surface gloss and interfere with particle coalescence. The powder should also be stored in sealed containers away from direct sunlight and sources of heat; prolonged storage above 40 °C can accelerate additive migration and reduce dry-flow stability.

On production-scale carousel and shuttle rotomoulding lines, LLDPE powders are typically heated at oven set-points between 260 °C and 300 °C. The critical control variable is peak internal air temperature, not oven residence time alone. Published processing guidance for linear low density rotomoulding powders indicates that a peak internal air temperature between 190 °C and 210 °C generally produces complete densification without excessive oxidative degradation. Higher peak internal air temperature values above 210 °C may produce yellowing, higher odour, and reduced environmental stress crack resistance due to thermo-oxidative chain scission. Lower peak internal air temperature values below 180 °C leave partially fused particles at the inner surface and reduce low-temperature impact. The difference between undercure and overcure can be narrow in multi-layer or foamed structures; in such cases the control band may be held to ±5 °C.

The actual optimum for Icorene 3560 G BWN 8423 depends on wall thickness, mould material, and part complexity. Thin parts below 3 mm lose heat quickly and may require higher oven set-points; thick parts above 10 mm require longer heating and risk over-cure on the inner surface while the mid-wall is still fused. Thermocouple placement in the mould cavity is the standard method for monitoring peak internal air temperature. Mould release and warpage are controlled by cooling rate; a staged air-cooling step before water spray reduces residual stress in thick sections. The material should not be removed from the mould until the inner surface is free of loose powder; demoulding too early causes delamination at the parting line.

What Happens to Impact and ESCR When the Grade Is Pigmented or Dry-Blended?

The BWN 8423 formulation already contains colour and stabiliser; additional dry-blending of pigment masterbatch is generally unnecessary for the intended outdoor and industrial applications. If a processor adds a separate masterbatch, the addition ratio becomes a critical threshold. In rotomoulding LLDPE, poorly dispersed pigment agglomerates at loadings above approximately 1.0 wt% can reduce instrumented puncture energy by more than 15% and shorten environmental stress crack resistance, because agglomerates at particle boundaries act as crack-initiation sites. The decrease is not linear; above a critical volume fraction the low-temperature impact property may fall rapidly. Published data for this specific Icorene BWN 8423 configuration with additional masterbatch is limited, so processors should evaluate compounded plaques under ISO 6603-2 or ASTM D3763 before production. The carrier resin of any masterbatch should also be an LLDPE or metallocene polyethylene with similar density; a low-density polyethylene or high-density polyethylene carrier can alter crystallisation kinetics and cause inconsistent shrinkage.

When dry-blending is unavoidable, it should be performed in low-shear tumble mixers rather than high-speed mixers, because high-shear mixing can generate fines and electrostatic surface charges that worsen dry-flow. The batch should be used within the shift to reduce segregation during storage. Oxidative induction time determined under ISO 11357-6 or ASTM D3895 is useful for verifying that the antioxidant package remains active after blending; a significant drop indicates stabiliser consumption and should trigger cycle-time or temperature adjustment.

The application profile follows from the density, environmental stress crack resistance, and low-temperature ductility of the LLDPE matrix. Rotomoulded parts in this product class include agricultural sprayer tanks, diesel fuel tanks, water storage tanks, material-handling bins, marine buoys, and outdoor enclosures. In chemical service, the polymer is commonly resistant to dilute acids, alkalis, and many aliphatic hydrocarbons at ambient temperature; however, published data for this specific configuration under concentrated oxidising acids, aromatic solvents, or chlorinated hydrocarbons is limited, and immersion testing under the actual service fluid is required. For potable-water contact, the final article should be evaluated under FDA 21 CFR 177.1520 or the applicable national migration standard; the presence of the BWN 8423 colour package does not automatically confer food-contact certification. For electronic or automotive components sold in Europe, the formulated compound should be checked against REACH and RoHS Directive 2011/65/EU, because colour concentrates may contain declarable heavy metals or organic pigments.

The grade is also selected where a high-density polyethylene article fails by environmental stress cracking in the presence of detergents, oils, or secondary cleaning agents. Its lower modulus accepts higher deformation before yielding, which makes it suitable for large flat panels that are subject to thermal expansion and flexural loading. Tensile data on rotomoulded specimens should be supplemented by dart impact tests on cut plaques from the actual part, using ASTM D3763 or ISO 6603-2, because fusion quality at corners and weld lines controls field performance more than the resin specification alone.

When This LLDPE Grade Replaces an HDPE or LDPE Rotomoulding Powder

Substituting Icorene 3560 G BWN 8423 for a high-density polyethylene rotomoulding powder reduces flexural modulus and upper service temperature but increases environmental stress crack resistance and low-temperature impact. Typical high-density polyethylene rotomoulding powders have densities between 0.940 g/cm³ and 0.946 g/cm³ and flexural moduli above 800 MPa; they are chosen for high stiffness, but their crystallinity can make them susceptible to environmental stress cracking in detergent, oil, or agricultural chemical contact. The LLDPE grade, with a density of 0.935 g/cm³, remains below the crystalline transition region where environmental stress crack resistance can fall sharply with increasing density. Compared with low-density polyethylene rotomoulding powders, which commonly have densities between 0.920 g/cm³ and 0.925 g/cm³, the Icorene grade has higher tensile yield stress and higher resistance to top-load deformation, while retaining sufficient ductility for deep undercuts. The melt flow rate near 6.0 g/10 min also lies in a mid-range that fills complex mould details without the excessive pinhole risk seen in very high-melt-flow low-density polyethylene.

In direct substitution trials, processors should not simply exchange powders at constant cycle time. The LLDPE grade may require a slightly lower oven set-point or shorter cooking time than a higher-density high-density polyethylene because its lower crystallinity melts and densifies earlier. Differences in shrinkage and warpage should be measured on the actual mould because the lower crystallinity of LLDPE produces lower total shrinkage but a greater tendency to distortion in flat panels. The colour and ultraviolet package in BWN 8423 may also alter surface appearance compared with natural high-density polyethylene or unpigmented LLDPE rotomoulding powders.

Operational boundaries for Icorene 3560 G BWN 8423 derive from its powder form and stabiliser package. Although polyolefins are not hygroscopic, surface moisture from condensation can produce blowholes in rotomoulding; if the powder is stored below 10 °C and then moved to a humid moulding hall, pre-drying at 60–70 °C for 2–4 h may be required. The grade should not be processed with amine-based or nitrile-containing additives that deactivate the hindered phenolic stabiliser package, nor with high levels of oxidising agents that consume the antioxidant during the oven cycle. Contamination with high-density polyethylene or low-density polyethylene powders should be prevented because density and rheology shifts can occur at charge ratios above 5 wt%. Regrind from rejected parts may be re-used in rotomoulding, but the particle shape of regrind differs from virgin powder, and its proportion should be kept constant to maintain dry-flow and impact consistency.