Braskem HDPE 0147 is a high-density polyethylene grade supplied as natural or coloured pellets for injection molding applications. The product is specified primarily by a melt flow rate of 7.0 g/10 min determined under ASTM D1238 at 190 °C/2.16 kg and a nominal density of 0.947 g/cm³ determined under ASTM D1505. These two anchors place the material in the mid-flow injection molding band of the supplier’s HDPE portfolio. The melt flow rate is high enough to fill thin-wall closures and multi-cavity houseware tools without the elevated pressures required for high-molecular-weight blow-molding grades, while the density remains in the range associated with stiffness, toughness, and moisture resistance.

Industrial applications for this product include injection-molded caps and closures, housewares, toys, small industrial containers, and general-purpose technical articles. The product should not be confused with HDPE film or extrusion-coating grades, which have melt flow rates below 1.0 g/10 min and are optimized for bubble stability or melt strength. The differences in molecular weight distribution and rheology that separate injection grades from extrusion grades are significant despite similar density values.

Melt Flow, Density, and Mechanical Benchmarks

The core specification anchors for Braskem HDPE 0147 are the melt flow rate and density. Manufacturer-published typical data for the grade also include mechanical and thermal values: tensile yield strength falls in the mid-twenties MPa range under ASTM D638-14, flexural modulus is reported near 1,100 MPa under ASTM D790-17, notched Izod impact is in the 4–7 kJ/m² band under ASTM D256-10, and Vicat softening temperature is near 126 °C under ASTM D1525-17. These mechanical values are not a sales specification; lot-specific certificates of analysis and the supplier’s current technical data sheet should be used for design calculations.

Because the density is 0.947 g/cm³, the material retains the crystalline character and solvent resistance typical of HDPE. The melt flow rate of 7.0 g/10 min corresponds to a moderate molecular weight that reduces injection pressure relative to lower-flow grades but still provides adequate notched impact and heat deflection properties for many non-pressure general-purpose articles. For applications requiring long-term environmental stress crack resistance measured under ASTM D1693, a higher-molecular-weight grade with a lower melt flow rate may be required.

Injection molding of Braskem HDPE 0147 is performed on reciprocating-screw machines with a general-purpose polyolefin screw. The recommended melt temperature window is 180 °C to 230 °C; the lower boundary is defined by insufficient flow and visible weld-line weakness in thin sections, while the upper boundary is set by oxidative degradation and viscosity reduction. Mold temperature is generally held between 10 °C and 40 °C. Lower mold temperatures reduce cycle time but increase orientation and differential shrinkage; higher mold temperatures improve surface finish but extend cooling time. Moisture absorption in HDPE is low, so pre-drying is not normally required. If condensation has formed on pellets or regrind contains more than 0.1% moisture, drying at 80 °C for 2 h is applied before processing.

Production-scale experience on multi-cavity cap and closure tools indicates that melt temperatures below 180 °C produce short shots in wall sections below 0.8 mm, particularly in molds with long flow lengths from a central sprue. Melt temperatures above 230 °C can lead to gate blush, yellowing, and reduced oxidative induction time. Screw speed is usually set between 80 rpm and 120 rpm for medium-sized molding machines, but the optimal setting depends on shot size and cycle time. Back pressure is maintained at low-to-moderate levels, typically 5–15 bar hydraulic, to avoid excessive shear heating. Injection speed is set high enough to fill before the melt freezes at the gate, but not so high that jetting occurs. The material follows shear-thinning behavior; at injection shear rates of 10³–10⁴ s⁻¹, apparent viscosity drops significantly from the low-shear plateau, allowing cavity filling at moderate pressures.

Clamp force sizing for this grade follows the same practice used for other HDPE injection grades: cavity pressure is estimated at 30–50 MPa multiplied by the projected area of the part and runner system. If the mold has insufficient venting at vent depths greater than the HDPE flash threshold of 0.02–0.03 mm, burn marks and diesel effect occur in blind pockets. Excessive vent depth produces flash at the parting line. Mold shrinkage for this density class is typically 1.5–3.0% according to ASTM D955-08; differential shrinkage between thick bosses and thin walls is the principal cause of sink marks, warpage, and dimensional instability in houseware and container lids.

Regrind of 0147 can be incorporated in molding operations provided that the feedstock is clean and not degraded. In injection molding, up to 20% regrind is common without significant loss of mechanical properties; higher regrind fractions can reduce notched Izod impact and increase melt flow variation. Batch-to-batch MFR variation for this grade is usually controlled within ±0.5 g/10 min; thin-wall and multi-cavity tools with wall thickness below 1.0 mm may need tighter internal control because small changes in melt flow shift fill and pack behavior. The effect of a 1.0 g/10 min increase in MFR can lower peak cavity pressure by 10–15% in high-speed cap molds, but published data for this specific configuration is limited and should be verified on the target machine.

What critical processing boundaries govern mold fill, shrinkage, and thermal stability?

The processing boundary for mold fill is controlled by melt temperature, injection speed, and the flow length through the runner and gate. At wall thicknesses below 0.8 mm, the flow length achievable with a 7.0 g/10 min HDPE is much greater than that of a 0.5 g/10 min blow-molding grade but lower than that of a 20 g/10 min high-flow injection grade. This means 0147 can fill thin sections, but the process window narrows when part geometry includes long ribs or hinges. If the injection speed is too low, the flow front freezes and creates visible weld-line separation; if the speed is too high, shear heating at the gate can exceed 230 °C locally even when barrel temperature is lower.

Shrinkage control requires packing pressure and time to compensate for the volume change from melt density to solid density. The density change from melt to solid for HDPE is approximately 0.15–0.20 g/cm³; correspondingly, the part volume decreases unless melt is added during packing. Packing pressures in the 50–80 MPa injection range are typical, but published data for this specific configuration is limited and should be validated with in-mold pressure transducers. Gate freeze time is determined by gate thickness and melt temperature; when the gate freezes too early, packing cannot compensate for shrinkage, and sink marks deepen. For thick-walled parts, cycle time is governed by cooling rather than filling, and mold temperatures at the higher end of the 10–40 °C range can reduce warpage but increase cycle time.

Thermal-oxidative stability is monitored by oxidative induction time under ASTM D3895-19. For HDPE of this density and melt flow class, a minimum OIT of 20 min at 200 °C is commonly used as an incoming-lot check, although grade-specific published data for Braskem HDPE 0147 is limited. Repeated hot-runner residence times above 230 °C can reduce OIT and shift color toward yellow. When machine shutdown is planned, the barrel should be purged with a lower-flow HDPE or a commercial purging compound to minimize retained oxidized material. Weld-line strength in injection molded HDPE is generally 60–80% of the base material tensile strength, depending on melt temperature and injection speed. Higher melt temperatures within the 180–230 °C window improve weld-line strength but increase cycle time. For snap-fit geometries, weld-line location should be moved away from high-stress regions or part design should include radii and flow leaders.

When 0147 Replaces a Lower-Flow HDPE Grade in Thin-Wall Tooling

Replacing a lower-flow HDPE blow-molding or extrusion grade with 0147 in an existing injection mold is not a simple drop-in change. The lower melt viscosity of 0147 reduces injection pressure and can improve fill, but the mold may begin to flash if clamp force and vent depths are not adjusted. Gate blush and jetting can also appear because the more fluid melt enters the cavity with a more unstable flow front. Conversely, replacing a higher-flow HDPE with 0147 may require higher melt temperature, higher injection pressure, or longer packing time to avoid short shots and sink marks. The increase in cycle time is often minor, but it must be captured in piece-cost calculations.

Environmental stress crack resistance is the most important property trade-off when moving from a lower-flow blow-molding grade to 0147. Testing under ASTM D1693 with a 10% Igepal CO-630 solution at 50 °C usually shows that blow-molding grades with melt flow rates of 0.3–1.0 g/10 min have longer failure times than injection grades with a melt flow rate of 7.0 g/10 min. This is expected because the higher molecular weight of the blow-molding grade provides greater tie-molecule density and slow crack growth resistance. For detergent bottles, fuel tanks, and stress-cracked agricultural chemical containers, lower-flow grades remain the correct choice. For general-purpose housewares, closures, and toys, the injection molding productivity of 0147 outweighs the ESCR difference.

The comparison in Table 2 is class-level rather than grade-specific and is intended for material selection at the concept phase. Specific Braskem grade values should be confirmed against current supplier datasheets and application-specific testing.

Food-contact use of Braskem HDPE 0147 requires lot-specific confirmation that the material is covered by the supplier’s food-contact compliance statement under FDA 21 CFR 177.1520 and, for EU markets, Regulation (EU) No 10/2011. Non-food industrial uses such as caps, pails, and housewares are not constrained by these certifications, but customers should confirm heavy-metal and hazardous substance compliance under REACH and RoHS as applicable. The material is not recommended for continuous immersion in strong oxidizing acids, chlorinated solvents, or aromatic hydrocarbons; for such environments, chemical resistance testing under ASTM D543 and stress cracking testing under ASTM D1693 should be conducted before production.