LyondellBasell Icorene 3545 NAT 0000 is a natural-colour linear low-density polyethylene resin supplied in pellet form. The designation NAT 0000 identifies the natural resin variant without the slip, antiblock, or UV-stabiliser loadings commonly added to film-specific grades, and the suffix 0000 refers to the standard lot-release formulation rather than a colour masterbatch. Technical data sheets for the 3545 grade report density by ISO 1183-1:2019 and melt mass-flow rate by ISO 1133-1:2022. Representative product-selection literature places density near 0.934 g/cm³ and melt mass-flow rate near 4.0 g/10 min at 190 °C/2.16 kg. The resin is therefore positioned as an intermediate-density linear low-density polyethylene with stiffness above conventional film-grade LLDPE and below high-density polyethylene.

Designation Decoding and Resin Classification

The grade identifier 3545 is a commercial designation rather than a direct numerical translation of melt index or density. The NAT designation indicates natural colour, while 0000 indicates the standard additive formulation. The base polymer is an ethylene/α-olefin copolymer; the precise comonomer identity is not stated in all publicly available selection literature, although the density and environmental stress crack resistance profile are consistent with LLDPE grades produced using a higher α-olefin. Published data for the specific comonomer of Icorene 3545 is limited. Mechanical property benchmarks are generated under conditioned protocols: tensile yield is determined by ASTM D638-14 at 50 mm/min, with representative selection literature values near 17 MPa. Elongation at break under ISO 527-2:2012 is typically reported above 800 %. Flexural modulus by ASTM D790-17 is commonly reported in the range of 600–700 MPa. Vicat softening temperature by ISO 306/A120 is near 121 °C, and the melting peak by ISO 11357-3:2018 is near 124 °C. These values are representative selection values and do not replace a lot-specific certificate of analysis.

What Limits the Processing Window in Rotational Moulding?

Rotational moulding trials conducted on shuttle-type biaxial equipment with oven-air temperatures of 280–320 °C and internal mould atmosphere temperatures reaching 200–230 °C establish a practical sintering window for this resin class. The melt mass-flow rate near 4.0 g/10 min provides sufficient viscous flow for bubble-free consolidation, but the comparatively low melt elasticity of linear low-density polyethylene can delay particle coalescence when peak internal air temperature remains below 190 °C. A heating-rate plateau before cooling is required; premature removal from the oven at internal air temperatures below 200 °C can produce pinhole defects and incomplete sintering at wall thicknesses greater than 6 mm. Biaxial rotation ratios of 4:1 to 5:1 are typically used; deviation from this range is a common cause of non-uniform wall thickness on large mouldings.

Cooling rate is a critical threshold variable. Slow air cooling at 10–15 °C/min increases crystallinity and density while reducing low-temperature impact in thick sections. Water mist cooling accelerates solidification and reduces warpage on large flat panels but raises residual stress and can generate shrinkage anisotropy. The maximum continuous service temperature for an unstabilised natural LLDPE grade is generally limited to 60–80 °C under low mechanical load. Sustained contact with strong oxidising acids, aromatic hydrocarbons, or chlorinated solvents accelerates environmental stress cracking and should be excluded unless end-use testing under ASTM D1693-21 or equivalent demonstrates acceptable performance.

On injection moulding machines using a general-purpose screw with a 20:1 to 25:1 length-to-diameter ratio and a compression ratio of 2.5:1 to 3.5:1, melt temperatures of 200–230 °C and injection pressures of 60–100 MPa are typical. Mould temperatures should be held at 10–40 °C to balance cycle time and shrinkage. The natural pellet feed does not require predrying unless condensation has formed on stored material; if hopper storage occurs above 60 % relative humidity, drying at 60–70 °C for 2 h is sufficient. Melt residence times exceeding 15 min at temperatures above 230 °C should be avoided because oxidative chain scission can reduce molecular weight and shift the melt flow rate upward.

When Compared with Conventional Butene-Comonomer LLDPE

When compared with butene-comonomer linear low-density polyethylene of similar density and melt flow rate, Icorene 3545 NAT 0000 occupies a different property balance if a higher α-olefin comonomer is used. Butene-grade LLDPE typically exhibits shorter tie-chain populations, lower dart impact, and reduced environmental stress crack resistance relative to hexene- or octene-copolymerised LLDPE at equivalent density. The density near 0.934 g/cm³ places Icorene 3545 above conventional blown-film LLDPE grades at 0.918–0.922 g/cm³, which increases flexural modulus but reduces clarity and tear resistance in thin-gauge film. The resin is therefore selected for semistructural mouldings, chemical containers, and rotationally moulded parts requiring stiffness rather than high-clarity film.

Compared with high-pressure low-density polyethylene of equivalent melt mass-flow rate, the linear molecular architecture reduces long-chain branching. The practical consequence is lower melt strength and narrower neck-in control during cast film operations, but higher tensile yield and improved environmental stress crack resistance. The reduced shear thinning can also raise screw torque in single-screw extrusion when a barrier screw designed for high-pressure LDPE is used. Production lines transferring from LDPE to this LLDPE grade should monitor melt pressure and screw amperage during the first 30–60 min of transition.

Mechanical property benchmarks are obtained only under conditioned protocols.

Mechanical property comparisons require identical specimen preparation and conditioning. Polyethylene properties are sensitive to cooling rate, density, and test speed. Tensile yield values near 17 MPa under ASTM D638-14 may not be reproduced on uncontrolled mouldings with rapid quench or high orientation. Flexural modulus data under ASTM D790-17 should be measured on conditioned specimens at 23 °C and 50 % relative humidity. Impact testing by ASTM D256-10 or ISO 180 is geometry-dependent; Izod values cannot be directly compared with Charpy values or with drop-weight impact tests on finished mouldings. The environmental stress crack resistance performance of the 3545 grade should be characterised using ASTM D1693-21 with 10 % Igepal CO-630 at 50 °C when chemical-container service is intended.

Food-contact suitability for the natural 0000 variant should be verified through the manufacturer’s certificate of compliance. The base olefin polymer may meet FDA 21 CFR 177.1520 and EU Regulation 10/2011 when the finished article satisfies applicable overall migration and specific migration limits. REACH Regulation (EC) 1907/2006 registration is maintained by the supplier. RoHS 2011/65/EU does not restrict polyethylene, but product-specific certificates should be checked for heavy-metal residues in stabiliser or catalyst packages. The following matrix summarises the principal compliance and test method designations referenced for this resin class.

Moisture uptake is minimal. The resin is not hydroscopic in the sense of polyamides or polycarbonate, but surface condensation on pellets stored in unheated warehouses above 60 % relative humidity can produce splay and surface pitting on moulded parts. Hopper drying at 60–70 °C for 2 h is sufficient when condensation is observed. Avoid combination with high levels of peroxide masterbatches unless specifically formulated for controlled crosslinking, because free-radical generation in the melt can shift the melt flow rate and gel content unpredictably. Copper and copper alloys should be avoided during long-term melt contact because copper ions catalyse polyethylene oxidation at processing temperatures.

On single-screw extrusion lines, feed-throat bridging is a common production failure when hopper temperatures exceed 50 °C, causing irregular output and surging. Screw cooling should be set to maintain a temperature gradient from feed to metering zone. Purging after natural LLDPE processing is recommended with a fractional-MFR LDPE or HDPE purge compound to reduce gel build-up on screw surfaces. Gels formed during prolonged residence time at high temperature are not solely cosmetic; they can act as stress concentrators in thin-walled mouldings and reduce impact performance under ASTM D256-10.