LyondellBasell Icorene 3560 G WHI 1603 is classified as a linear low density polyethylene compound supplied with a white pigmentation package. The Icorene 3560 G base polymer is typically listed with a melt flow rate of 6.0 g/10 min at 190 °C under a 2.16 kg piston load when tested in accordance with ISO 1133-1:2022, and a density of 0.935 g/cm³ when measured by ISO 1183-1:2019. Because the WHI 1603 suffix denotes a compounded colour-stabilised variant, the exact melt flow rate, ash content, and oxidation induction time must be confirmed against the lot-specific certificate of analysis. The material is intended for rotational moulding and related powder-processing operations where a density of 0.935 g/cm³ and a melt flow rate of 6.0 g/10 min support powder densification and bubble removal.

The density of 0.935 g/cm³ places the product in the upper segment of the linear low density polyethylene range, below medium-density polyethylene but above conventional 0.918–0.922 g/cm³ film-grade LLDPE. This density level produces a crystallinity commonly measured between 45% and 55% by differential scanning calorimetry at a heating rate of 10 K/min under nitrogen per ISO 11357-3:2018. In processing terms, the product exhibits a broader crystalline melting range than high-density polyethylene; the main endotherm typically lies between 122 °C and 128 °C for this resin class. These class-level values indicate that the material requires an oven plateau above 190 °C internal air temperature to fully densify and eliminate trapped air in rotational moulding.

How Does Icorene 3560 G WHI 1603 Differ From LDPE, HDPE and Metallocene LLDPE?

Relative to high-pressure low density polyethylene, the linear low density structure contains a controlled level of short-chain branching introduced by copolymerisation rather than free-radical reactor branching. The result is a higher tensile yield stress at equivalent density when tested to ISO 527-2:2012, lower long-chain branching, and a narrower molecular weight distribution that affects shear thinning behaviour in extrusion and rotational moulding. A conventional LDPE with identical melt flow rate usually displays lower zero-shear viscosity and stronger strain hardening in extensional flow; the LLDPE counterpart can show less sag but also slower orientation-induced crystallisation in film processes. Compared with HDPE of 0.950 g/cm³ or above, the 0.935 g/cm³ density reduces flexural modulus and increases environmental stress crack resistance under ASTM D1693 conditions, although exact stress crack performance for the white compound must be taken from the manufacturer’s datasheet. Compared with single-site or metallocene LLDPE grades, a conventional Ziegler-Natta LLDPE may display broader comonomer composition distribution, which influences heat seal initiation temperature, extractable content, and low-temperature impact consistency. If a narrower composition distribution is required for organoleptic-sensitive applications, a metallocene product may be evaluated in parallel.

Rotational moulding with Icorene 3560 G WHI 1603 is constrained by the balance between bubble dissolution and melt sag. A sample with a melt flow rate of 6.0 g/10 min has lower zero-shear viscosity than a 3.0 g/10 min LLDPE rotomoulding powder, which shortens the time required for particle coalescence but increases flow and sag in wall sections above 6 mm. Typical oven set-points for this density class range from 290 °C to 315 °C; the internal air temperature measured inside the mould should reach 190–210 °C and be held for 2–5 min to allow bubble diffusion. If the internal air temperature is raised beyond 220 °C, oxidation of the white compound can increase yellowness index and reduce ductility. Cooling rate is a further control variable: air cooling at 8–12 °C/min followed by forced-air demoulding at 60–65 °C lowers warpage and post-mould shrinkage relative to rapid water quenching. Published machine-specific data for this exact configuration is limited, so these processing windows are class-typical and should be verified by in-mould thermocouple trials.

On single-arm shuttle rotational moulding machines, the powder is charged directly into the mould; dry-flow and bulk density therefore control cavity fill consistency. Powders in this density and melt-flow class commonly exhibit bulk densities of 0.35–0.45 g/cm³ when measured by ASTM D1895 Method A, and a dry-flow time in the range of 28–34 s per 50 g through a standard funnel. A deviation in dry-flow by more than ±3 s from the supplier reference can indicate particle fines, pigmentation agglomeration, or moisture surface pickup. Because the WHI 1603 variant contains a white pigment and stabiliser package, the particle size distribution and dry-flow values may differ from the unpigmented Icorene 3560 G; incoming inspection should compare the lot against the supplier’s reference sample rather than against a natural powder specification.

When a Precompounded White Feedstock Replaces Masterbatch Addition

The WHI 1603 designation indicates that the white pigment and associated stabiliser system are incorporated into the resin during manufacturing rather than dry-blended at the processing floor. In rotational moulding, dry blending a colour masterbatch into natural Icorene 3560 G powder introduces the risk of segregation during powder transfer, especially when the masterbatch and base powder differ in bulk density by more than 0.10 g/cm³. A precompounded white powder reduces shot-to-shot colour variation and prevents pigment agglomerates from accumulating in the mould corners or at weld lines. However, the titanium dioxide loading can affect the thermal conductivity of the melt and the oxidative degradation pathway. For exterior applications, ultraviolet absorber and hindered amine stabiliser levels must be evaluated in the final part by accelerated weathering to ISO 4892-2:2013 cycle 1 or ASTM G155 cycle 1; published data for this specific compound is limited, so test plaques should be moulded from the commercial lot and exposed alongside a control.

Pigment particles in semicrystalline polyethylene can act as nucleation sites, increasing crystallisation temperature and reducing spherulite size. In a white compound, the rheological effect is usually modest at loadings below 5 wt%, but excessive pigment agglomeration can reduce tensile elongation at break and notched impact energy. When injection moulding or extrusion is used instead of rotational moulding, screw wear and melt filtration behaviour become relevant. Titanium dioxide abrasiveness can increase barrel and screw wear rates, particularly in unlined barrels with flight clearances above 0.25 mm. Screen packs of 60/80/100 mesh may need replacement more frequently than with natural LLDPE if pigment dispersion is inadequate.

Sintering, Bubble Evolution and Crystalline Morphology in the White Compound

Densification of a 0.935 g/cm³ LLDPE powder involves particle necking, interstitial air dissolution, and crystallite perfection. The rate of sintering is inversely proportional to zero-shear viscosity; at 190 °C, the zero-shear viscosity for this melt-flow class is commonly between 2,000 Pa·s and 4,000 Pa·s. Air bubbles trapped in the melt shrink by diffusion; their elimination time scales with the square of the initial bubble radius and inversely with the pressure difference across the bubble wall. Sections above 8 mm may retain bubbles if cooling begins before the internal air temperature reaches the plateau. The white pigment increases opacity and slightly increases thermal conductivity, but it does not eliminate the need for a plateau above 190 °C. After cooling, the crystalline morphology consists of lamellae whose thickness depends on the cooling rate; slow cooling at 8–12 °C/min yields a tensile yield stress of approximately 14–18 MPa and a flexural modulus between 500 MPa and 700 MPa on ISO 178:2019. These are class-typical mechanical values for LLDPE rotomoulding grades at this density, not lot-specific guarantees.

Bubble dissolution in rotational moulding can be approximated by a diffusion-limited radius reduction in which the time for a bubble to vanish is proportional to the square of the initial bubble diameter and inversely proportional to the gas diffusivity. For a 0.935 g/cm³ LLDPE melt, nitrogen and oxygen diffusivities are on the order of 10⁻⁶ to 10⁻⁵ cm²/s at 200 °C. This means air cells with initial diameters of 100 µm can be removed within seconds, but cells larger than 500 µm or trapped between uncoalesced powder layers may persist into the solid part. Therefore, the densification step is controlled not only by temperature but by particle size distribution and the removal of fines that melt early and form a low-permeability skin.

Specimen preparation influences the comparison between suppliers. When properties are reported on compression-moulded plaques to ISO 293, the crystallisation history differs from that of a rotomoulded part cooled at 8–12 °C/min. Compression-moulded sheets cooled at 15 °C/min under pressure typically show a smaller spherulite size and slightly lower crystallinity than slow-cooled rotomoulded walls. Tensile tests on ISO 527-2 type 1B specimens machined from compression-moulded sheet may therefore overestimate ductility and underestimate modulus relative to actual part performance. For design validation, test specimens should be cut from production parts or rotomoulded plaques on the same machine and cooling cycle.

The molecular weight distribution of a 6.0 g/10 min LLDPE rotomoulding grade is typically broader than that of a metallocene LLDPE and narrower than that of a high-pressure LDPE. The breadth influences the transition from solid-like sintering to melt flow in the oven. A broader distribution can provide a wider sintering window because lower-molecular-weight chains melt and flow early while higher-molecular-weight chains retain melt strength. However, the same breadth can increase extractable content and reduce organoleptic performance. The exact polydispersity index of Icorene 3560 G WHI 1603 is not stated in all public documents; publication of the full molecular weight distribution would require gel permeation chromatography data from the manufacturer.

Incoming inspection should include melt flow rate, density, ash content, particle size distribution, and dry flow. A typical LLDPE rotomoulding powder is ground to a particle size distribution with D50 between 250 µm and 500 µm and D90 below 800 µm; finer particles improve surface detail but reduce bulk density and increase dust. The white compound may contain fines that affect fusing. The bulk density difference between natural and white lots should be recorded. If the powder is stored in an unheated warehouse at high humidity, surface moisture can be removed in a dehumidified hopper at 70 °C for 30 min before moulding. This is particularly relevant for multi-layer applications where trapped steam creates interfacial bubbles.

Although Icorene 3560 G WHI 1603 is primarily considered for rotational moulding, the same density and melt flow rate can be processed by injection moulding in short-flow parts. Injection moulding machines should use a general-purpose polyolefin screw with an L/D ratio of 20:1–24:1 and a compression ratio of 2.5:1–3:1. Melt temperatures of 210–240 °C and mould temperatures of 20–40 °C are typical for LLDPE compounds. Shrinkage can range from 1.5% to 2.5% depending on flow direction and wall thickness; holding pressure should be adjusted to minimise sink marks. The white colourant can affect surface gloss and hide minor flow lines but does not replace the need for correctly sized gates and vents.

The primary failure modes observed on production rotational moulding lines are incomplete densification, oxidative yellowing, and warpage. Incomplete densification appears as microvoids and rough internal surfaces when the plateau internal air temperature does not stay above 190 °C for the required time. Oxidative yellowing is detected by an increase in yellowness index measured to ASTM E313; white compounds are sensitive to yellowness values above 2–3 units for aesthetic applications. Warpage arises from asymmetric cooling or ejection above 65 °C. To control warpage, forced-air cooling should be uniform across the mould surface, and the part should be removed only after the demoulding temperature is below the heat deflection threshold for the wall thickness.

A compliance review for a white LLDPE compound should include verification of food-contact status under regional requirements such as FDA 21 CFR 177.1520 for olefin polymers, European Union EU 10/2011 and its amendments, and any applicable REACH SVHC disclosure. The exact compliance status of Icorene 3560 G WHI 1603 is supplier-specific and application-dependent; users must request the current regulatory statement from LyondellBasell rather than infer compliance from the polymer class alone. The product is not specified for chemical immersion or high-temperature pressure piping. Continuous-use temperatures above 60 °C can reduce creep resistance and accelerate stabiliser consumption. Storage conditions should avoid prolonged exposure to direct sunlight and relative humidity above 85%; although polyethylene has low equilibrium moisture absorption, surface moisture can generate steam defects during moulding.

For potable water contact, additional certifications such as NSF/ANSI 61 or KTW/BWGL may be required depending on jurisdiction. The base resin or compound status should be verified with the supplier; no inference should be made from a food-contact grade alone.