Supplied as a grey-pigmented linear low density polyethylene rotational moulding powder, Icorene 3560 G GRY 7295 is processed into seamless hollow parts where wall thickness uniformity, environmental stress crack resistance, and low-shear consolidation are critical. Melt flow rate under ISO 1133-1:2022 at 190 °C/2.16 kg is 6.0 g/10 min, and density under ISO 1183-1:2019 is 0.935 g/cm³. The pre-coloured grey system removes the need for separate colour concentrate let-down in most non-colour-matched applications. The downstream scenarios below cover chemical storage, dry bulk handling, off-highway fluid reservoirs, aquaculture and agricultural vessels, utility enclosures, and marine float shells.

Chemical Storage Vessels and Dual-Containment Sumps

Charging a carousel-type rotational mould with Icorene 3560 G GRY 7295 at an oven set point of 285–300 °C allows the powder to pass through sintering and densification without the shear heating associated with screw-compounded thermoplastics. The powder is dry-blended with a hindered-amine light stabilizer masterbatch at 0.2–0.5 wt% for outdoor sumps; regrind from trimmed necks and failed parts is limited to 15 wt% because higher fractions reduce environmental stress crack resistance under ASTM D1693-15e1 Condition C. The chemical-service shell is final-moulded with a wall thickness of 6–9 mm, using a biaxial rotational speed ratio of 4:1 and an internal air temperature of 205–215 °C held for 18–24 min. After the oven stage, forced air cooling is used until the mould surface reaches 85–90 °C, followed by water mist cooling to a demoulding temperature of 65 °C. Demoulding above 70 °C has been observed to produce sidewall distortion in this wall-thickness range, particularly on rectangular sump geometries with flat vertical faces.

On carousel machines with 3–6 arms, a recurring processing bottleneck occurs when the demoulding sequence is accelerated below 18 min total cooling for 8 mm walls: sink marks form near flat wall sections because differential crystallinity develops between the outer and inner surfaces. Moulds with sharp transitions from the wall to the top rim require radiused corners of at least 12 mm to prevent stress concentration during shrinkage. Batch-to-batch fluctuation in powder dry-blend homogeneity is controlled by tumbling at 20–30 rpm for 15–20 min before charging; improper blending of UV masterbatch produces visible grey streaks on the outer surface of the tank.

Conformity assessment for these vessels follows ASTM D1998-21 for upright polyethylene storage tanks and ASTM D543-21 for chemical resistance testing against specific stored fluids. Contact with food or potable water under 21 CFR 177.1520 is assessed separately when the end user specifies such service, because the grey pigment package must be verified in the final formulation. Finished chemical tanks range from 500 L to 10,000 L, including vertical cylindrical vessels, secondary containment sumps, acid neutralization tanks, and double-wall spill pallet basins. Operational boundaries include case-by-case resistance testing for aromatic solvents and chlorinated hydrocarbons, and avoidance of continuous service above 40 °C with aggressive oxidizers unless coupon immersion data under ASTM D543-21 demonstrate acceptable mass change and retention of tensile properties.

For dry bulk handling hoppers subjected to repeated impact from quartz sand and angular aggregates, the grey LLDPE powder is processed on shuttle-type rotational moulding equipment with fabricated steel tooling at a wall thickness of 8–12 mm. The formulation is charged at 100 wt% powder, with 20–30 wt% in-house regrind accepted because hoppers for non-critical bulk solids do not carry the ESCR requirements of chemical storage; however, regrind above 30 wt% increases surface pitting and reduces puncture impact when tested by ISO 6603-2:2000. The mould internal air temperature is brought to 200–210 °C and held for 20–26 min depending on steel thickness, with rotational ratio 3:1 to 4:1. Finished components are bulk totes, tapered discharge hoppers, abrasive sludge trays, and chute liners of 1–2 m³ capacity. Compliance for dry bulk handling is anchored to ASTM D5276-19 drop impact testing of loaded containers and ASTM D638-22 tensile verification of cut specimens from the moulded wall. The material is not inherently antistatic; if the hopper is to be used in a combustible dust environment with minimum ignition energy below 10 mJ, a separate surface-resistance-control strategy is required, and ATEX Directive 2014/34/EU equipment category verification falls outside the resin datasheet.

What Regrind Fraction Preserves −40 °C Impact in Off-Highway Diesel Tanks?

Regrind fraction is not a single property modifier in off-highway diesel tank shells; it simultaneously shifts low-temperature dart impact, ESCR, and post-mould dimensional stability. For diesel reservoirs of 40–200 L with wall thickness 5–8 mm, the charge is set at 100 wt% virgin Icorene 3560 G GRY 7295, with regrind capped at 10 wt% because higher fractions are associated with cold-impact failures at −40 °C under multi-axial puncture per ISO 6603-2:2000. The shell is sintered in a carousel mould at 270–290 °C and an internal air temperature of 200–210 °C, with post-mould fluorination specified when hydrocarbon permeation limits are contractual. Fluorination changes the inner surface energy and reduces permeation; the effect is validated by gravimetric cup procedures per SAE J2665. Fluid resistance is checked by ISO 175:2010 immersion testing of moulded coupons in the specified diesel, hydraulic oil, or urea solution. The end products are non-pressurized diesel and hydraulic oil reservoirs for compact construction equipment, agricultural machinery, and off-highway vehicle platforms. Operational boundaries exclude gasoline service and continuous fluid temperatures above 60 °C unless the final part has been revalidated.

In aquaculture holding tanks and livestock waterers, the absence of a weld seam after rotational moulding removes the crevice biofilm accumulation observed in welded polypropylene constructions. The grey LLDPE charge is 100 phr, with 0.2–0.4 wt% hindered-amine light stabilizer masterbatch and no additional pigment let-down because GRY 7295 already contains the colour package. Wall thickness is typically 4–7 mm, and the mould is rotated at 4:1 to reach an internal air temperature of 200–205 °C for 14–20 min. Terminal products include fish holding tanks, hatchery troughs, livestock waterers, and agricultural sprayer sump tanks. Conformity for food-contact or drinking-water service is formulation-specific: the base polyethylene may be assessed under 21 CFR 177.1520, but NSF/ANSI 61 acceptance of the grey pigment must be verified before potable-water use. Continuous outdoor exposure requires UV stabilization and periodic inspection for surface oxidative cracks under ASTM D1693-15e1 Condition A; tanks cleaned with aggressive disinfectants should be checked by ASTM D543-21 immersion tests before production.

When a Grey LLDPE Powder Replaces Fibreglass in Utility Enclosures

The replacement of fibreglass with rotationally moulded grey LLDPE in utility enclosures is driven by impact toughness and part consolidation. A typical enclosure shell of 5–6 mm wall thickness is charged at 100 phr Icorene 3560 G GRY 7295, with 1–3 wt% UV masterbatch for 10-year outdoor exposure and 5–15 wt% clean in-plant regrind. Oven process conditions are 280–300 °C with internal air temperature maintained at 205–210 °C for 16–22 min; aluminium tooling with 2–3° draft angles minimizes mould release interference. The material is not flame retardant and is classified as UL 94 HB unless a specific flame-retardant additive is validated separately; enclosures requiring V-0 should not use this grade as a standalone polymer. Conformity documentation for electrical enclosures references RoHS Directive 2011/65/EU, REACH Regulation (EC) No 1907/2006, and IEC 60529 for ingress protection where the finished enclosure is tested as an assembly. Terminal products include valve boxes, pump covers, meter housings, underground utility pits, and machinery guards manufactured as single-piece bodies with integrally moulded ribs and inserts.

Seawater Immersion Service Without a Barrier Skin

Marine float bodies require an unpainted LLDPE shell that withstands seawater absorption, ultraviolet degradation, and cyclic mechanical loading from wave motion. The powder is charged at 100 phr, blended with 2–3 wt% hindered-amine light stabilizer masterbatch and 0.1–0.3 wt% antioxidant masterbatch, while regrind is limited to 10 wt% for foam-filled shells. The shell is rotationally moulded to 5–8 mm, sintered at 270–290 °C, and cooled slowly until 70 °C before demoulding to avoid sink marks on flat pontoon faces. Seawater resistance is verified by ASTM D543-21 immersion tests; ultraviolet weathering is assessed under ISO 4892-2:2013 or ASTM G155-21 with prescribed exposure intervals. Terminal components are mooring buoys, floating dock segments, harbour fender bodies, and dredge pipeline floats filled with closed-cell polyurethane foam. Unfilled rotational-moulded shells are not rated for buoyancy and must be foam-filled or compartmentalized to meet marine flotation requirements.