LG Chem HDPE SP980 is a high-density polyethylene grade positioned in the manufacturer’s polyolefin portfolio for extrusion applications in which melt strength, environmental stress crack resistance, and surface uniformity have greater priority than injection-cycle fluidity. Published typical physical-property values are centred on a density of 0.956–0.960 g/cm³ measured according to ISO 1183-1:2019 and a melt flow rate of 0.70–0.90 g/10 min at 190°C/5 kg in accordance with ISO 1133-1:2022. These characteristics place the grade in the medium-high molecular weight region of high-density polyethylene, below injection-moulding grades in flowability but above fractional-melt pipe grades in extrudability. The resulting profile is directed toward rigid sheet, thermoforming feedstock, industrial profiles, cable management conduits, and non-pressure or low-pressure pipe. Lot-specific values should be confirmed against the certificate of analysis, because published data for this specific configuration is limited to manufacturer-controlled typical ranges.

Compliance declarations available for SP980 cover EU food-contact framework Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm² for plastics intended for contact with food, and US FDA 21 CFR 177.1520 for olefin polymers in contact with aqueous, acidic, and fatty foods under conditions of use A through H. The grade is also subject to REACH registration and RoHS Directive 2011/65/EU as amended by (EU) 2015/863; specific SVHC content should be confirmed from the safety data sheet. These regulatory positions are standard for unfilled high-density polyethylene but do not constitute food-contact approval for finished articles. Final compliance depends on pigmentation, process additives, and migration testing of the formed part.

What processing window governs SP980 sheet and profile extrusion?

SP980 is processed on single-screw extruders with a length-to-diameter ratio of 24:1 to 30:1 and a barrier screw designed for high-density polyolefins. A typical barrel profile, starting from the feed zone, is 180°C, 190°C, 200°C, and 205°C; adapter and die zones are held at 210–220°C. Melt temperatures above 240°C increase oxidative degradation risk, resulting in gel formation and surface sharkskin on extruded sheet. A melt pump between the screw tip and die reduces surging and improves gauge uniformity; melt pressure before the screen pack is typically 15–25 MPa for a 60 mm extruder at 50–80 rpm, but the value must be adjusted for screw geometry and back pressure. Filtration with a 60/100/60 mesh screen pack is standard on sheet and profile lines; an increase in screen-pack differential pressure above 8–10 MPa indicates contaminant accumulation and requires replacement before melt temperature control deteriorates. Pre-drying is not normally required below 60% relative humidity. At RH above 60%, surface moisture can generate small bubbles or splay in thick sheet, and a desiccant hopper at 70–80°C for 2 h is applied.

On sheet lines, the moderate-high melt strength of SP980 stabilises the melt curtain between die lips and cooling rolls. A polishing stack with a matte or mirror finish is set to 70–90°C for gloss control and minimal residual orientation. Roll gaps are configured to produce a sheet drawdown ratio below 1.5:1; higher drawdown increases longitudinal orientation and reduces thermoforming uniformity. For profiles, calibration plates or vacuum sizers are used at 15–25°C water temperature to set dimensions. The low melt index limits sag in thick-wall profiles but also increases screw back-pressure; extruder motors must be sized for a power draw of approximately 0.25–0.35 kWh/kg depending on screw speed, die restriction, and melt temperature.

When SP980 replaces a fractional-melt PE100 pipe grade in non-pressure service

SP980 should not be specified for PE100 pressure pipe under ISO 9080:2022 unless the lot has been certified for long-term hydrostatic strength at the required service temperature. PE100 compounds are formulated to achieve a minimum required strength of 10.0 MPa at 20°C for 50 years; published data for SP980 under ISO 1167-1:2006 is limited. In non-pressure drainage, conduit, and cable protection, this distinction is less critical, and SP980 can be selected for higher output and lower melt temperature than a fractional-melt pressure-pipe grade. The substitution must preserve the minimum ring stiffness required by the installation. If a product standard specifies SN4 or SN8 ring stiffness in accordance with ISO 9969:2016, wall thickness must be calculated from flexural modulus rather than copied from pressure-pipe wall thickness tables.

Batch acceptance and contamination control during incoming resin inspection

Incoming lots of SP980 are tested for melt flow rate, density, and residual volatile content. A lot-to-lot melt flow rate shift of more than ±0.05 g/10 min from the certified value can indicate bimodal reactor split variation or contamination with a lower-molecular-weight grade; such material should be segregated before silo blending. Density shifts greater than ±0.002 g/cm³ can shift flexural modulus and thermoforming sag time. Silo handling must avoid cross-contamination with polypropylene or polycarbonate; even 0.5% contamination can create visible gels, delamination, and reduced Charpy impact. Metal separation with rare-earth magnets or eddy-current units is recommended before extrusion; screen packs and melt pumps do not protect the screw from hard contaminants.

Evaluating substitution risk across the LG Chem HDPE product range

The comparison highlights a key substitution conflict: the higher flow of SP980 relative to PD0100 reduces extrusion back-pressure but removes the long-term pressure rating. Against BE0400, SP980 has a less pronounced shear-thinning response, which improves thickness uniformity in flat sheet but provides less parison hang strength in blow moulding. Against ME8000, SP980 has significantly higher notched impact and environmental stress crack resistance, but its low MFR will overheat and degrade if forced through small injection sprues or thin-wall moulds without sufficient gate sizing.

Thermoforming behaviour is controlled by sheet orientation and reheat uniformity

Thermoforming behaviour of SP980 sheet is dominated by sheet orientation, reheat uniformity, and the forming temperature window between 125°C and 140°C. Quartz or ceramic heaters must deliver uniform surface temperature within ±3°C to avoid premature sagging in the centre and inadequate stretching at the periphery. The sag time of SP980 is intermediate between a blow-moulding grade and an injection-moulding grade; higher molecular weight delays sag, but excessive heat can reduce the oriented strength of the finished part. Plug-assisted forming with syntactic foam or heated aluminium plugs reduces thinning in deep-draw geometries. After forming, parts should be cooled in the mould to below 60°C before trimming to minimise dimensional recovery. Amine-based antistatic agents and certain hindered amine additives can deposit on die lips and alter surface roughness; direct combination should be avoided unless the masterbatch is pre-dispersed and evaluated on the production line.

Environmental stress crack resistance in SP980 is influenced by comonomer distribution, cooling rate, and residual orientation. Rapid quenching in sheet extrusion produces smaller spherulites and lower crystalline perfection; slower cooling in thick profiles increases density and can reduce ESCR slightly. In contact with detergent solutions or alcohols, stress cracking initiates at surface defects and propagates through interlamellar tie-chain regions. The medium-high molecular weight of SP980 increases the number of tie chains and entanglements, shifting F50 values in 100% Igepal to 500–1000 h according to ASTM D1693-15. However, pigments, regrind, and process oils can reduce this value by 30% or more; any formulation change should trigger a full ESCR re-qualification.

On production-scale sheet lines, a recurrent failure mode is melt-temperature drift in the adaptor section when screen packs are not replaced. The resulting gel streaks in the finished sheet are not always visible at the extruder head; they appear after thermoforming as local thinning or stress-whitening near the clamp frame. The preferred control response is to log melt pressure before and after the screen pack, replace the screens when differential pressure exceeds 9 MPa, and purge with a high-viscosity HDPE transition material rather than lowering the barrel profile. Reducing melt temperature below 190°C can generate flow marks and poor roll release, while raising it above 230°C increases oxidation and odour. The practical operating window for SP980 is therefore narrower than for lower-molecular-weight sheet grades, and control of melt pressure is the primary limiting variable on high-output calendering lines.