PetroChina Dushanzi HDPE DMDA-8008 is a high-flow injection-moulding grade with a nominal melt mass-flow rate of 8 g/10 min at 190 °C/2.16 kg per ISO 1133-1:2022 and a density of 0.956 g/cm³ per ISO 1183-1:2019. In thin-wall dairy spread tubs and deli containers produced on 250–350 t clamp-force injection-moulding machines with a 22:1 L/D general-purpose polyolefin screw, the practical melt-temperature window is 210–250 °C measured at the nozzle, with a mould temperature of 20±5 °C; the feed-throat temperature is held below 60 °C to prevent bridging. The formulation is 96.0–98.0 wt% virgin DMDA-8008 and 2.0–4.0 wt% white masterbatch carried in an HDPE base that itself meets the same food-contact requirements. The injection profile is set to fill 0.6–1.2 mm sidewall sections in 0.8–1.5 s through hot-runner valve gates, with gate shear rates kept below 10,000 s⁻¹ to limit melt fracture and gate blush; holding pressure is 35–50 MPa, back pressure is 0.5–1.0 MPa, and screw recovery speed is trimmed so that melt residence time at 230 °C does not exceed 6 min. Food-contact compliance is based on FDA 21 CFR 177.1520 for olefin polymers, EU Regulation (EU) No 10/2011 with an overall migration limit of 10 mg/dm² or 60 mg/kg in final articles, and GB 4806.7-2016 for finished food-contact plastics. If resin stored below 20 °C enters a high-humidity production hall, 2–4 h hopper warming is used; drying is not normally required because moisture absorption of this HDPE grade is below 0.01%. The terminal product types are thin-walled dairy spread tubs, deli containers, and portion cups in the 0.5–2.0 L range, where the high flow rate permits sink-free ribs and snap-fit lid undercuts without exceeding 12 s cooling time.

What becomes of the melt-flow boundary when DMDA-8008 is used in non-carbonated beverage closures?

For screw caps on non-carbonated beverages, dairy bottles, and household chemical containers, the 8 g/10 min melt flow rate of DMDA-8008 moves the injection-pressure requirement below that of fractional-MFI HDPE closure grades, but it also narrows the sealing-torque retention window under creep loading. The closure formulation is typically 98.5 wt% DMDA-8008, 1.0–1.5 wt% colour masterbatch, and 0.5–1.0 wt% slip/anti-block masterbatch; total additive masterbatch is not allowed to exceed 2.0 wt% in food-contact closures to avoid destabilising the olefin polymer basis of FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011. Multi-cavity hot-runner cap moulds with valve gates of 0.8–1.2 mm diameter operate at melt temperatures of 220–240 °C, mould temperatures of 20±5 °C, holding pressures of 40–60 MPa, and cooling times of 6–9 s for a 1.8–2.0 mm nominal skirt wall. On production-scale equipment, the main failure mode is not short-shot filling but loss of removal torque after top-load stacking; therefore closure print torque retention is screened per ASTM D2063-22 over a 24 h interval, and environmental stress-cracking resistance is checked per ASTM D1693-15 condition B for formulations that will contact surfactant-containing liquids. The terminal products are tamper-evident screw caps for still water, dairy drinks, dry grocery jars, and household cleaner bottles; carbonated-beverage closures are excluded from this construct unless the neck finish and liner system are re-validated for carbon dioxide permeation and creep at 4 °C storage.

Open-head pails of 5 L, 10 L, 20 L, and 25 L capacity for food powders, paints, and non-hazardous chemicals are injection-moulded with DMDA-8008 at 100 wt% for food-grade pails, or with up to 15 wt% clean in-house regrind from the same grade for industrial pails; in UN-certified dangerous-goods pails, recycled content is excluded or re-certified under the national competent authority. The downstream process uses single- or two-cavity cold-runner moulds, clamp forces of 700–1000 t, melt temperatures of 225–245 °C at the nozzle, mould temperatures of 20–30 °C, injection pressures of 80–100 MPa, and a stepped holding-pressure profile with total hold time of 12–18 s. Sink marks at the handle pinch-off are controlled by packing the undercut area with 45–60 MPa for 3–5 s after fill; wall thickness is maintained at 1.5–2.5 mm. Compliance is anchored to FDA 21 CFR 177.1520 and EU Regulation (EU) No 10/2011 for food-grade pails, and to the UN Model Regulations Chapter 6.1 packaging performance tests for pails intended for regulated goods, including drop and stacking tests. Terminal product types include open-head pails with tamper-evident lids for food ingredients, decorative coatings, and industrial liquids, but hot filling above 60 °C or contact with oxidising acids requires chemical resistance validation beyond the standard food-contact test battery.

When an HDPE crating grade meets ISO 8611-1:2011, the warp criterion shifts

For stackable agricultural crates, meat/fish totes, and distribution boxes, DMDA-8008 is blended at 70–85 wt% with 15–30 wt% recycled HDPE crate regrind in non-food industrial applications; where the crate contacts food directly, only virgin DMDA-8008 is used to keep the material declaration within the olefin polymer boundary of EU Regulation (EU) No 10/2011 or FDA 21 CFR 177.1520. The injection-moulding process involves two-plate cold-runner tools with clamp forces of 800–1400 t, melt temperatures of 225–245 °C, mould temperatures of 15–25 °C, and a profiled injection velocity that starts at 60–80 mm/s to fill the lower ribbed sections before decelerating in the rim area. Holding pressure is 45–65 MPa, cooling time is 18–30 s for 3.5–5.0 mm nominal wall thickness, and the mould opening is delayed until the rib root temperature falls below 80 °C to reduce warpage. Field-scale data from production lines indicates that the lower notched impact of an 8 g/10 min HDPE relative to fractional-MFI crating grades, as measured by ISO 179-1:2010, makes sharp internal corners and gate placement more critical; ribs must be radiused at no less than 0.5 mm and gates should not be located in load-bearing corners. Stacking performance is evaluated under ISO 2234:2000 or ASTM D642-20, while pallet-box versions are tested under ISO 8611-1:2011; terminal product types are stackable crates, ventilated agricultural totes, and fold-down logistics containers in the 20–70 L volume class.

0.956 g/cm³ HDPE in living hinges, toy blocks, and EN 71-3 migration limits

DMDA-8008 is used in toy blocks, storage boxes, and housewares where fast filling and short cycle time are decisive; the formulation is 98.0–99.0 wt% DMDA-8008 with 1.0–2.0 wt% heavy-metal-free masterbatch selected against EN 71-3:2019+A1:2021 migration thresholds and ASTM F963-17 total heavy-metal limits. Multi-cavity cold-runner injection tools produce parts with wall thicknesses of 1.2–2.5 mm at melt temperatures of 210–240 °C, mould temperatures of 15–25 °C, injection/hold pressures of 30–50 MPa, and total cycle times of 12–20 s. Compliance is established under REACH Regulation (EC) No 1907/2006 Annex XVII for phthalate restrictions, EN 71-3:2019+A1:2021 for soluble element migration, and ASTM F963-17 for heavy-metal content in toy substrates. The terminal product type covers injection-moulded toy construction blocks, storage boxes with integrally moulded snap-fit closures, and household hangers; components requiring prolonged hot-water immersion above 70 °C or dishwasher exposure in load-bearing parts are excluded from the standard DMDA-8008 processing window unless post-moulding annealing is introduced.

As a masterbatch and additive-compound carrier, DMDA-8008 is used at 60–80 wt% as the HDPE matrix with 20–40 wt% pigment or mineral additive in a co-rotating twin-screw extruder with 40:1 L/D, barrel temperatures of 160–200 °C, screw speeds of 400–800 min⁻¹, and strand pelletizing under a water bath; the carrier is subject to REACH Regulation (EC) No 1907/2006 registration and the masterbatch must be re-certified for EU Regulation (EU) No 10/2011 or FDA 21 CFR 177.1520 if it enters food-contact end-articles; terminal product types are pelletized HDPE masterbatches and filled compound granules for injection moulding and blow moulding.