Dow HDPE DMDA-6147 NT 7
- Product Name: Dow HDPE DMDA-6147 NT 7
- Factroy Site: Yinchuan, Ningxia, China
- Price Inquiry: sales8@ascent-chem.com
- Manufacturer: Ascent Petrochem Holdings Co., Limited
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- Dow HDPE DMDA-6147 NT 7 is typically used in formulations when melt flow rate, density, and molecular weight distribution and melt temperature, injection pressure, and mold temperature must be controlled within specific ranges.
| HS Code | 761625 |
| Product Name | Dow HDPE DMDA-6147 NT 7 |
| Polymer Type | High Density Polyethylene (HDPE) |
| Density | 0.953 g/cm³ |
| Melt Index 190 C 2 16 Kg | 0.70 g/10 min |
| Tensile Strength At Yield | 26 MPa |
| Tensile Strength At Break | 31 MPa |
| Elongation At Break | 800% |
| Flexural Modulus | 1100 MPa |
| Vicat Softening Temperature | 125°C |
| Heat Deflection Temperature 0 45 Mpa | 70°C |
| Environmental Stress Crack Resistance Escr | >1000 h |
| Hardness Shore D | 65 |
| Melting Point | 130°C |
| Mold Shrinkage | 1.5-3.0% |
| Brittleness Temperature | -70°C |
| Water Absorption | <0.01% |
As an accredited Dow HDPE DMDA-6147 NT 7 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Dow HDPE DMDA-6147 NT 7 typically comes in 25 kg polyethylene bags, with 55 bags per pallet totaling 1,375 kg. |
| Container Loading (20′ FCL) | 20′ FCL loading of Dow HDPE DMDA-6147 NT 7: standard 25 kg bags, palletized, shrink-wrapped, securely stowed for ocean freight. |
| Shipping | Dow HDPE DMDA-6147 NT 7 is a non-hazardous high-density polyethylene resin. It is shipped as solid pellets in 25 kg bags, octabins, or bulk trucks/railcars. No UN number, hazard class, or special placards required. Keep dry, clean, and away from heat/UV; avoid contamination during transport. |
| Storage | Store Dow HDPE DMDA-6147 NT 7 in a cool, dry, well-ventilated area away from direct sunlight, heat, and ignition sources. Keep original bags or containers sealed, palletized, and off the floor. Protect from moisture, dust, and contamination. Avoid contact with strong oxidizers. Do not stack excessively high. Use first-in, first-out stock rotation. Follow the manufacturer’s SDS and local regulations. |
| Shelf Life | Shelf life: 24 months in unopened original packaging stored cool, dry, away from direct sunlight, heat, moisture, and contamination. |
Dow HDPE DMDA-6147 NT 7 is classified as a high-molecular-weight high-density polyethylene blow-moulding resin with a melt flow index of 0.09 g/10 min under ASTM D1238 at 190 °C/2.16 kg and a density of 0.953 g/cm³ under ASTM D792 at 23 °C. These two values place the grade inside the accumulator-head extrusion window. Low melt flow index provides parison hang strength sufficient for shot weights between 5 kg and 120 kg, depending on machine size. Density defines areal mass per millimetre of wall thickness at 0.953 kg/m². A 220 L drum with 0.8 m² surface area and 3 mm nominal wall therefore consumes approximately 2.3 kg of resin before pinch-off flash and handle material are added. The following application zones are separated by distinct compliance loads, tooling types, stress-crack exposure, and failure modes.
| Input parameter | Value | Reference |
|---|---|---|
| Melt flow index | 0.09 g/10 min | ASTM D1238 |
| Density | 0.953 g/cm³ | ASTM D792 |
| Typical accumulator-head melt temperature | 190–230 °C | Machine-specific process window |
| Typical blow pressure | 0.55–0.80 MPa | Production line data |
| Regrind addition in coextruded fuel tanks | Up to 40 wt% | Manufacturer practice |
| Outdoor stabilisation requirement | 2.5–3.5 wt% carbon black or 0.3–0.6 wt% HALS active | ISO 4892-2 verification |
What Wall Thickness Distribution Is Required for UN 1H1 Drum Drop Compliance?
In 220 L tight-head drum production on accumulator-head machines with screw diameters between 80 mm and 120 mm and L/D ratios of 24:1 to 30:1, parison programming controls axial wall distribution rather than leaving thickness to die gap alone. DMDA-6147 NT 7 is processed at barrel temperatures from 190 °C to 230 °C, with the accumulator head held at 210 °C to 220 °C. Shot weight for a 220 L drum typically ranges from 7.5 kg to 9.5 kg, depending on chime mass and closure thread design. Blow pressure is set at 0.60 MPa to 0.80 MPa, and mould temperature is maintained at 10 °C to 30 °C. The sidewall target is 2.0 mm to 3.5 mm. Top and bottom chime zones are thickened to 3.5 mm to 5.0 mm because drop and stacking loads concentrate at these radii. A parison drop time of 6 s to 12 s is used, with die gap adjusted between 1.5 mm and 3.0 mm to keep parison swell above 30% when referenced against final part diameter. Production-scale trial data show radial wall thinning at the pinch-off line and axial fold-over when clamp speed exceeds 400 mm/s. Screw speed is normally limited to 20 rpm to 50 rpm. On 90 mm extruders, sustained screw speeds above 80 rpm generate local melt temperatures above 240 °C, producing gel defects in the parison. UN certification for a 1H1 tight-head drum requires drop testing at 1.2 m for packaging group II and 1.8 m for packaging group I at −18 °C under 49 CFR 178.603. Stacking performance is verified for 28 days at 40 °C under 49 CFR 178.606. Terminal products are UN-classed polyethylene drums for chemicals, lubricants, and food-ingredient liquids where the fabricated article is assessed under 21 CFR 177.1520 end-use requirements.
Coextrusion Blow Moulding of Six-Layer Fuel Tank Structures
Fuel tank shells in the 40 L to 80 L range are coextruded with DMDA-6147 NT 7 serving as both the outer and inner HDPE layer. A six-layer structure is configured as HDPE/regrind/adhesive/EVOH/adhesive/HDPE. The EVOH barrier layer occupies 1.5 wt% to 3 wt% of total wall thickness. The in-line regrind layer may carry up to 40 wt% of the part weight if scrap is dedusted and transferred without fines segregation. Viscosity matching between the HDPE layer and the EVOH layer at 230 °C and shear rates from 100 s⁻¹ to 1,000 s⁻¹ is the primary process control variable. If the EVOH enters the die stack above 240 °C, rapid degradation creates gels and black specks. Die head temperatures are therefore set at 210 °C to 220 °C. The accumulator head must deliver a parison with uniform layer distribution, using drop times of 5 s to 10 s for tank tooling. Mould cooling uses water at 10 °C to 20 °C, with cycle times of 120 s to 180 s. EVOH must be pre-dried at 80 °C for 4 h to 6 h to below 0.02 wt% moisture. Regrind purity below 99.5% displaces the adhesive layer and causes delamination at the HDPE/adhesive boundary. Fuel tank assemblies are tested under ECE R34 for mechanical integrity. Hydrocarbon permeation is controlled by the EVOH barrier layer because monolayer HDPE permeation is orders of magnitude higher. Where CARB LEV III or equivalent evaporative emission limits apply, final tank permeation is validated on the assembled component rather than on plaque samples. Terminal products are fuel tanks for passenger cars, utility vehicles, agricultural tractors, and marine gasoline systems.
For agrochemical bottle production across 1 L to 20 L narrow-mouth formats, DMDA-6147 NT 7 is used primarily where stress-crack resistance must be verified against aggressive packaged formulations. Shuttle machines running up to 12 cavities are used for small bottles. Accumulator machines are used for larger multi-cavity tools. Melt temperatures of 190 °C to 210 °C, blow pressure of 0.50 MPa to 0.70 MPa, and mould temperatures of 10 °C to 25 °C are standard. Wall thickness is 0.6 mm to 1.2 mm for 1 L bottles and 1.5 mm to 2.5 mm for 20 L containers. Handle pinch-off zones are thickened by 20% to 30% relative to sidewalls to prevent splitting at the weld line. Closure bosses are moulded with E-type or BSP thread forms and require retained torque after 24 h at 50 °C. Induction seal liners use a 0.5 mm to 1.0 mm foamed polyethylene layer with aluminium foil; seal peel strength measured under ASTM F88 should exceed 4 N/15 mm. For aromatic solvents such as xylene, monolayer HDPE permeation exceeds 1 g·mm/m²/day at 23 °C, so barrier fluorination or coextruded barrier layers may be required. Environmental stress crack resistance is tested under ASTM D1693 condition B in 100% Igepal CO-630 at 50 °C. Lot acceptance should be based on a minimum F50 value agreed with the pesticide registrant rather than on a single uncontrolled data point. Surface treatment before printing is by corona discharge to a minimum wetting tension of 42 mN/m under ASTM D2578 or by flame treatment on handle sections. Compliance for agrochemical packaging includes US 40 CFR 156.140 container requirements and UN packaging instructions for hazardous goods. Terminal products are pesticide bottles, growth regulator jugs, and liquid fertiliser containers.
Marine Buoyancy Enclosures Demand UV Stabiliser Masterbatch Rates Above 2 wt% or Carbon Black Above 2.5 wt%
The natural grade contains only processing antioxidant protection and is not intended for long-term outdoor exposure without additional stabilisation. Marine floats, mooring buoys, and dredge sleeves moulded from DMDA-6147 NT 7 require addition of a 40% carbon black masterbatch at 2.5 wt% to 3.5 wt% or a HALS/UV absorber package at 0.3 wt% to 0.6 wt% active basis. Accelerated weathering tests under ISO 4892-2 cycle 1 should demonstrate retained tensile elongation above 50% after 2,000 h for tropical service. Blow-moulded floats are produced on accumulator-head machines with wall thickness of 4 mm to 8 mm. A moulded-in bung provides pressure equalisation against internal condensation. Buoyancy calculations use the density difference between seawater at 1.025 g/cm³ and the polymer at 0.953 g/cm³: net lift is approximately 72 kg/m³ of solid polymer. Hydrostatic hoop stress is estimated by σ = P × D / (2 × t). At 10 m depth with pressure of 0.1 MPa, a 1.0 m diameter float with 10 mm wall thickness develops 5 MPa hoop stress, which is within a conservative design limit for short-duration submersion. Wall thickness is instead governed by impact loads from docking and wave slamming. Izod impact values under ASTM D256 at −20 °C are used as a lot quality gate. Production floats have shown circumferential splits at mould parting lines when regrind levels exceed 30 wt%, and UV-degraded surface chalking has initiated microcracks that propagate under flexural cyclic loading. Terminal products are navigation buoys, floating dredge pipeline sections, and aquaculture cage collars.
Where vertical and horizontal water storage tanks from 500 L to 5,000 L are required, DMDA-6147 NT 7 is blow moulded on accumulator-head machines of 120 mm to 150 mm screw diameter. The resin is combined with 2 wt% to 4 wt% carbon black masterbatch when the tank is exposed to sunlight or with 0.5 wt% to 1.0 wt% HALS stabiliser masterbatch for coloured or translucent service. Melt temperature is held at 210 °C to 230 °C. Parison drop times above 15 s induce sag that thins the upper sidewall below design values. Wall section for a 2,000 L vertical tank is designed at 5 mm to 8 mm in the cylindrical body and 8 mm to 12 mm at integrally moulded fittings and outlets. Design hoop stress is capped at 5 MPa to 6 MPa at 20 °C, with long-term creep modulus measured under ISO 899-2. Outlet bosses are moulded with BSP or butt-fusion stub ends. Threaded brass inserts are excluded because differential thermal expansion creates interface stress above 2 MPa under normal storage temperature cycling. Potable water tanks fabricated from this grade are tested on the finished part to NSF/ANSI/CAN 61 extraction limits. Field hydrostatic failures correlate with pinch-off wall thinning below 3 mm across the lower knuckle when the parison programmer lacks sufficient point resolution to maintain that transition. Terminal products are agricultural water storage vessels, rainwater harvest tanks, and potable water reservoirs after end-use certification.
When Flame-Retardant Specifications Exclude Halogenated Synergists in Logistics Bins
Because the 0.09 g/10 min melt flow is too low for conventional injection filling of thin ribs, logistics bins, foldable container sleeves, and returnable dunnage are blow moulded from DMDA-6147 NT 7. Walls are set at 3 mm to 6 mm. The parts are corrugated or foamed to increase bending stiffness without increasing shot weight. Unmodified HDPE is rated HB under UL 94. Meeting V-2 or V-0 with halogen-free systems requires addition of magnesium hydroxide or ammonium polyphosphate intumescent masterbatch at 30 wt% to 55 wt%. These loadings raise melt viscosity and narrow the processing window by ±5 °C. Accumulator-head melt temperature must not exceed 210 °C because premature intumescence and water release from mineral fillers create surface pits and parison voids. Impact strength falls below 20 kJ/m² when filler loading exceeds 40 wt%; Charpy impact is measured under ISO 179-1/1eA at −20 °C. Flame-retardant logistics bins are therefore specified only where reduced ignitability or V-2 class is sufficient rather than full V-0 duty. Production uses 20 wt% to 30 wt% clean regrind from rejected bins, provided it is re-dried to below 0.05 wt% moisture and dedusted before feeding. Terminal products are returnable automotive dunnage, warehouse totes, and folding bulk containers.
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- Dow HDPE DMDA-6147 NT 7 is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
- COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales8@ascent-chem.com.
DOW HDPE DMDA-6147 NT 7 is a high-molecular-weight high-density polyethylene homopolymer supplied as natural-color pellets. The grade is intended for continuous extrusion blow molding of large rigid containers and technical parts requiring elevated melt strength and long-term environmental stress crack resistance. Supplier-published nominal values list density as 0.948 g/cm³ determined by ASTM D1505 or ISO 1183-1, and melt index as 0.07 g/10 min determined by ASTM D1238 at 190°C and 2.16 kg. The NT 7 suffix designates a natural color product without added carbon black or UV stabilizer. The combination of low melt index and medium-high density gives the polymer a high zero-shear viscosity, high melt strength, and improved slow crack growth resistance relative to lower-molecular-weight HDPE grades.
In blow molding operations, the material is normally processed with melt temperatures between 200°C and 220°C. The low melt index produces high die-head pressure and requires accumulator-head or shuttle machines designed for high-viscosity HDPE. Because published machine-specific pressure drop data for DMDA-6147 NT 7 is limited, initial production trials should record extruder motor amperage, head pressure, melt temperature, and parison hang time against the machine manufacturer’s maximum ratings. Start-up from a fractional-melt-index HDPE should be preceded by a screw purge to avoid excessive start-up torque.
What Limits the Extrusion Processing Window for a 0.07 g/10 min HDPE?
Melt temperature is the primary control variable for surface quality and parison integrity in high-molecular-weight HDPE extrusion. Barrel settings commonly begin at 180°C in the feed zone, rise to 200°C in the compression zone, and hold at 210°C to 220°C in the metering zone and accumulator head. If melt temperature falls below approximately 190°C, the critical shear rate for the resin may be exceeded at the die land, producing sharkskin or melt fracture on the parison. Temperatures above 220°C may accelerate oxidative degradation during residence times typical of large accumulator heads, especially if production stops exceed 10 min. The upper limit is therefore a function of residence time, head volume, and the antioxidant package carried by the natural resin.
On a 60 mm single-screw extruder with a grooved feed section and 24:1 L/D ratio, screw speed is typically limited by motor current rather than melt quality. The 0.07 g/10 min melt index increases specific energy demand compared with 0.30 g/10 min HMW-HDPE grades. Operators may need to reduce screw speed by 10% to 15% during changeover to maintain melt temperature and head pressure below the machine nameplate limits. Screw geometry, die gap, and accumulator volume change the exact load response; published data for this specific configuration is limited.
Die swell is shear-rate dependent and influences parison wall thickness programming. For HDPE blow molding grades, die swell can range from 15% to 35% under typical output rates, but the exact value for DMDA-6147 NT 7 requires capillary rheometry or die-in-flow measurement. Parison sag is retarded by high molecular weight. The resin’s melt strength permits longer hang time for large diameter-to-length ratios, but the parison programmer must account for reduced drawdown when switching from a lower-molecular-weight resin. Programmed wall thickness profiles that are set for fractional-melt grades may create thick bottom or pinch-off areas if reused without adjustment.
When DMDA-6147 NT 7 Replaces a Fractional-Melt-Index Grade in Blow Molding
Replacement of a 0.30 g/10 min HDPE with DMDA-6147 NT 7 alters environmental stress crack resistance, impact toughness, and extrusion throughput. The density difference may be small; many fractional-melt blow molding grades have densities near 0.950 g/cm³, while DMDA-6147 NT 7 is specified at 0.948 g/cm³. The main difference is molecular weight. Under ASTM D1693 Condition B in 100% Igepal, DMDA-6147 NT 7 typically exceeds 600 h to F50, whereas a lower-molecular-weight grade of similar density may fail between 20 h and 50 h depending on comonomer content and specimen preparation. This shift reflects higher tie-chain density rather than a change in density alone.
Flexural modulus changes with density, not directly with melt index. The published nominal flexural modulus for DMDA-6147 NT 7 is near 1,100 MPa under ASTM D790. A higher-density fractional-melt HDPE at 0.952 g/cm³ may reach 1,300 MPa. When the resin is substituted into container tools designed for higher-modulus HDPE, top-load strength may decrease if wall thickness remains constant. Compression testing of finished containers should follow ASTM D2659 or the plant’s internal top-load procedure after first article trials.
The high-molecular-weight structure also improves low-temperature ductility and slow crack growth resistance in full-container drop tests. However, the same structure reduces melt flow and may decrease extruder output at constant screw speed. The conversion decision should therefore be based on finished-part performance requirements and cooling-time constraints, not on raw material cost alone. Production trials with existing molds and downstream handling equipment are required because published data for tool-specific cycles with this grade is limited.
Environmental stress crack resistance in DMDA-6147 NT 7 is evaluated routinely by ASTM D1693, but the test has inherent variability because failure time depends on specimen thickness, notch quality, and test temperature. For aggressive liquid packaging, ASTM D1693 screening should be supplemented by full-container tests under stressed conditions and elevated temperature. The resin is suitable for contact with detergents, surfactant-based cleaners, mild acids, and many aqueous industrial solutions. It is not recommended for continuous immersion in strong oxidizing acids, aromatic hydrocarbons, chlorinated solvents, or ketones at elevated temperatures because these media may cause swelling, oxidative attack, or accelerated environmental stress cracking.
Low-temperature impact resistance in high-molecular-weight HDPE is better than in fractional-melt grades of similar density. Finished part testing should use the actual container geometry and drop height; standard methods such as ASTM D2463 for drop impact of blow molded containers provide more relevant data than small-scale notched tests. Containers made from DMDA-6147 NT 7 generally maintain ductile puncture behavior below -20°C, but handling and impact performance depend on part thickness, cooling rate, and stress concentration at pinch-offs and parting lines.
Auditing Lot Consistency and Incoming Inspection
Incoming resin lots are tested against the supplier certificate of analysis using ASTM D1238 for melt index at 190°C/2.16 kg and ASTM D1505 for density. The certificate typically reports these values plus ESCR or other lot-specific data. Moisture content is not normally specified for HDPE because the resin is not hygroscopic; however, surface condensation can occur if cold pellets are transferred into a warm process area at high relative humidity. Testing by ASTM D6980 or a simple loss-on-drying balance can detect surface moisture above 0.05%.
Melt index and density alone may not capture lot-to-lot differences in molecular weight distribution. When wall thickness control or melt pressure shifts unexpectedly, capillary rheometry under ASTM D3835 or dynamic rheology at angular frequencies from 0.1 rad/s to 100 rad/s can reveal differences in high-molecular-weight tail distribution. Melt flow ratio, defined as the ratio of high-load melt index to standard melt index, may also be recorded. Published data for this specific resin across multiple lots is limited; however, the supplier’s certificate and retained samples allow comparative analysis when processing deviations occur.
Mold Temperature, Blow Pressure, and Part Shrinkage Interaction
Blow mold cooling controls cycle time in large-part extrusion blow molding. Mold temperatures of 10°C to 30°C are generally used for HDPE, with lower temperatures accelerating skin freeze-off. If the mold surface is too cold, visible flow lines or internal stress can be introduced because the melt is quenched before full relaxation. Blow air pressures for high-molecular-weight HDPE typically range from 0.6 MPa to 0.9 MPa. Increasing pressure improves material contact with the mold cavity but does not reduce cooling time once the part reaches the mold wall; cooling time then scales with wall thickness squared.
Mold shrinkage is influenced by density, mold temperature, part thickness, and cooling uniformity. After demolding, post-mold shrinkage may continue for 24 h to 48 h, especially in thick-walled drum and container bases. Dimensional inspection should be delayed until the part reaches uniform ambient temperature. For DMDA-6147 NT 7, production shrinkage values should be established on the actual tool and cycle because published shrinkage data is tool-specific and not a reliable predictor of finished part dimensions.
Nominal typical values from supplier-published data are shown below. These values are not specification limits and should not be used for final part design without additional testing.
| Property | Nominal Value | Test Standard |
|---|---|---|
| Density | 0.948 g/cm³ | ASTM D1505 / ISO 1183-1 |
| Melt index | 0.07 g/10 min | ASTM D1238 / ISO 1133-1:2022 |
| Environmental stress crack resistance | >600 h | ASTM D1693 Condition B |
| Flexural modulus | 1,100 MPa | ASTM D790 / ISO 178 |
| Tensile strength at yield | 27 MPa | ASTM D638 / ISO 527-2 |
Polyethylene homopolymers of this class are commonly evaluated for food-contact use under 21 CFR 177.1520, provided the final article meets extractive limits and end-use conditions specified in the regulation. European Union compliance is assessed under Regulation (EU) 10/2011 through migration testing and supplier declarations; the grade name alone does not constitute compliance evidence. RoHS and REACH obligations apply to the finished imported or sold article at the tonnage or component level. Processors should obtain the supplier’s regulatory status letter and verify that the composition aligns with specific application restrictions before commercial production.
The natural NT 7 formulation does not include carbon black or a UV stabilizer package. Outdoor service with direct sunlight exposure can cause photo-oxidative embrittlement, surface crazing, and loss of environmental stress crack resistance. For exterior applications, a UV-stabilized or carbon-black-containing HDPE grade should be selected, or the finished article must be protected by an approved additive system compounded during processing.
The resin is used in blow molded industrial containers, open-head drums, intermediate bulk container inner bottles, agricultural chemical packaging, and large technical parts that require high ESCR and low-temperature ductility. It is not intended for injection molding, film extrusion, rotational molding, or pressure pipe applications. For pressure pipe, a PE100-certified material with minimum required strength and hydrostatic design basis under ISO 9080 is required; DMDA-6147 NT 7 is not a pressure pipe grade.
Compared with general-purpose HDPE injection molding grades with melt indices of 5 g/10 min to 20 g/10 min, DMDA-6147 NT 7 has much higher melt viscosity and cannot fill thin-wall injection molds. Compared with medium-density polyethylene and linear low-density polyethylene, it has higher crystallinity, higher density, and lower permeability to water vapor. Compared with higher-density fractional-melt HDPE blow molding grades, it may offer slightly lower stiffness due to its 0.948 g/cm³ density but often provides higher molecular weight and longer stress crack resistance. Selection between DMDA-6147 NT 7 and other HDPE grades depends on the dominant failure mode of the finished part; if the part fails by slow crack growth or low-temperature impact, high molecular weight is critical. If the part fails by top-load buckling, density and wall thickness dominate.
Processors operating at high throughput should verify that the accumulator head pressure, extruder drive capacity, and mold cooling system are adequate for the lower melt index. Published data for tool-specific cycle time, die swell, and shrink with this exact grade is limited; plant-scale trials remain the definitive method for process establishment.
