Braskem (Quattor) HDPE HS5407 is a pelletized high-density polyethylene resin classified for injection-moulding conversion. The material is characterized by a nominal melt flow rate of 7.5 g/10 min when tested at 190 °C under 2.16 kg load to ISO 1133-1, and a nominal density of 0.956 g/cm³ determined to ISO 1183-1. These two properties place HS5407 in the moderate-flow, high-stiffness segment of HDPE injection resins. Published supplier data list tensile yield strength at approximately 27 MPa to ISO 527-2, flexural modulus at approximately 1,150 MPa to ISO 178, and Vicat softening temperature near 127 °C to ISO 306 under a 10 N load. The values are nominal reference points for incoming resin qualification and should not be treated as guaranteed minimums unless expressly stated in a purchase specification. The intended conversion window covers rigid closures, thin-wall containers, housewares, toys, and appliance components where high density contributes to surface hardness and dimensional stability.

What limits the melt processing window of HS5407 in high-speed injection moulding?

The melt processing window is constrained primarily by thermal degradation and rheological response rather than by hygroscopic absorption. Polyethylene pellets are not inherently hygroscopic, but surface condensation can occur when cold resin is transferred into a humid moulding hall. Under relative humidity above 60% or when hopper temperature is below the dew point, pre-drying at 70–80 °C for 2 h in a hot-air hopper dryer or desiccant dryer with a dew point below -20 °C reduces splay and surface bubbling in moulded parts. Published capillary rheometry data for this specific grade are limited, but the melt flow rate of 7.5 g/10 min indicates lower melt viscosity than fractional-melt blow-moulding or pipe HDPE grades with melt flow rates below 1 g/10 min.

In reciprocating-screw injection moulding machines with screw length-to-diameter ratios of 20:1 to 25:1 and compression ratios from 2.5:1 to 3.5:1, the recommended barrel profile is 180–210 °C in the rear feeding zone, 190–220 °C in the centre zone, 200–230 °C in the front metering zone, and 200–220 °C at the nozzle. Melt temperatures above 230 °C have been associated with yellowing and odour generation in unfilled HDPE conversion. Residence time at maximum melt temperature should not exceed 10–15 min; above 220 °C, residence time should be shortened to avoid gel formation and black specks. Mould temperatures are typically maintained between 10 °C and 40 °C. Lower mould temperatures shorten cycle time but can increase warpage in parts with non-uniform wall thickness; higher mould temperatures improve weld-line strength and surface replication at the expense of longer cooling time.

Injection pressure is typically set between 60 MPa and 100 MPa, with hold pressure at 40–70% of the injection pressure. Back pressure is maintained at 0.5–1.5 MPa to ensure melt homogeneity without excessive shear heating. Screw peripheral speed is usually limited to 0.2–0.5 m/s. In multicavity hot-runner tools with valve gating, excessive screw decompression above 3–5 mm can introduce air into the melt stream and generate burn marks at the flow front. The observed production bottleneck in thin-wall containers with flow length-to-thickness ratios above 200:1 is not plastication capacity but venting; vent depths of 0.02–0.03 mm and high injection velocities of 150–300 mm/s are required to prevent gas entrapment and short shots.

Mechanical property benchmark under dry-as-moulded conditions

The dry-as-moulded mechanical profile of HS5407 is representative of a unimodal injection-grade HDPE with density above 0.950 g/cm³. The table below consolidates selected nominal published values.

The flexural modulus of approximately 1,150 MPa positions HS5407 above many low-density and linear low-density polyethylenes but below highly filled or reinforced HDPE compounds. The notched Izod value of 4.0 kJ/m² at 23 °C indicates moderate toughness. Compared with high-molecular-weight HDPE film and blow-moulding grades, HS5407 exhibits lower impact strength and shorter environmental stress-crack resistance because of its lower molecular weight and higher density. Environmental stress-crack resistance data published under ASTM D1693 for this specific configuration are limited; however, injection-grade HDPE with density near 0.956 g/cm³ generally shows shorter F50 failure times than pipe or blow-moulding grades with density below 0.950 g/cm³. The density increase that raises flexural modulus also reduces slow crack growth resistance when the finished article is exposed to fatty oils, soaps, or wetting agents under continuous stress.

Regulatory status must be verified against current supplier documentation before qualifying the material for food, medical, or toy applications. Typical food-contact declarations for Braskem HDPE resins reference FDA 21 CFR 177.1520(c) for olefin polymers. European Union compliance under Regulation (EU) No 10/2011 is generally addressed through overall migration testing on the finished article rather than on the pellet alone. The grade contains antioxidant and acid-scavenger additives typical of polyolefin stabilization packages; specific additive identities are disclosed in the safety data sheet and regulatory declaration supplied by Braskem. REACH registration status is maintained by the resin producer, while RoHS compliance for heavy metals is normally established by the converter through finished-article analysis to IEC 62321. These certifications must be confirmed before use in food-contact or medical packaging because the final article geometry, processing temperatures, and downstream printing or lamination steps can alter migration behaviour.

When HS5407 replaces a fractional-melt HDPE in a rigid component

Substitution of a fractional-melt HDPE with HS5407 reduces melt pressure and improves mould filling, but it also lowers environmental stress-crack resistance and notched impact strength. A blow-moulding or pipe grade with melt flow rate below 1 g/10 min at 190 °C/2.16 kg has a higher average molecular weight and often a bimodal molecular weight distribution, which enhances slow crack growth resistance and long-term hydrostatic strength. HS5407, as a moderate-flow injection grade, sacrifices these long-term failure modes for shorter cycle time and easier cavity filling. In applications involving continuous hoop stress, contact with detergent solutions, or exposure to fatty food simulants, replacement should not proceed without stress-crack validation to ASTM D1693 or a finished-part constant-strain test.

Relative to high-flow HDPE injection grades with melt flow rates above 20 g/10 min, HS5407 provides better stiffness and toughness but requires higher injection pressure and may exhibit more warpage in thin-wall parts due to higher molecular orientation. Compared with an isotactic polypropylene homopolymer of similar melt flow rate, HS5407 has lower flexural modulus and lower Vicat softening temperature but better notched impact strength at low temperatures and lower density. In applications requiring continuous service above 90 °C, polypropylene or glass-reinforced resins are generally more suitable than HDPE. In applications requiring ESCR above 100 h under ASTM D1693, a blow-moulding or pipe grade with lower density is normally preferred.

For closure applications, the combination of high density and moderate flow in HS5407 supports wall thickness reduction without excessive warpage. However, closures with living hinges are typically moulded from polypropylene because HDPE grades have inferior flexural fatigue resistance. If HS5407 is evaluated for a snap-fit or press-fit closure, the design must include generous corner radii and avoid sharp notches because the notched Izod value of 4.0 kJ/m² indicates moderate notch sensitivity. In production trials, sprues and runners should be recycled at controlled ratios; regrind levels above 20 wt% may reduce impact strength and increase the risk of black specks after multiple heat histories. The resin is supplied as pellets suitable for gravimetric or volumetric dosing, but blend consistency should be monitored when regrind is introduced to avoid density and melt flow drift.

Shrinkage predictions require cavity-specific measurement rather than datasheet constants

Mould shrinkage for HDPE with density near 0.956 g/cm³ and melt flow rate near 7.5 g/10 min typically falls between 1.5% and 2.5% in an unrestricted plaque, depending on wall thickness, gate geometry, mould temperature, and hold pressure. Datasheet shrinkage values are not a substitute for cavity-specific measurement because shrinkage is anisotropic and is influenced by flow orientation. Parts moulded with long flow paths can show higher tensile modulus parallel to flow and reduced impact strength perpendicular to flow. Direct edge gates produce higher orientation near the gate and greater differential shrinkage than hot-runner valve gates. For precise cavity sizing, the mould should be cut on the basis of measured shrinkage from a prototype tool or from a flow-representative plaque, not from a single datasheet constant.

Weld-line strength is affected by melt temperature and mould temperature within the previously stated ranges. Higher melt temperature improves molecular diffusion across the weld line, but excessive temperature degrades the polymer. Higher mould temperature, up to 40 °C, improves weld-line strength by slowing cooling and allowing more time for chain entanglement. In thin-wall containers with multiple gates, venting of the weld-line region is necessary to prevent trapped gas from reducing weld strength. The fill speed should be profiled to avoid jetting from the gate; jetting produces a rounded, poorly packed flow front and reduces both surface quality and tensile strength. A short hold-pressure time at the end of filling can leave sink marks in thick sections, while excessive hold pressure can create mould sticking and ejection marks.

The processing boundaries for HS5407 are therefore defined by melt temperature control below 230 °C, mould temperature control between 10 °C and 40 °C, injection pressure from 60 MPa to 100 MPa, and regrind inclusion below 20 wt% unless process validation demonstrates otherwise. The resin should not be processed with amine-based polyolefin additives because of potential nitric oxide formation under high-temperature degradation. The use of silicone mould release should be minimized in parts destined for printing or adhesive bonding because surface migration of low-molecular-weight silicone can reduce ink adhesion. Published data for this specific configuration are limited for creep behaviour and long-term chemical resistance, so finished-article testing remains the final qualification step for load-bearing or aggressive chemical service.