Dow HDPE DMDA-8904 NT 7
- Product Name: Dow HDPE DMDA-8904 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-8904 NT 7 is typically used in formulations when melt index and density and processing temperature and pressure must be controlled within specific ranges.
| HS Code | 685388 |
| Density | 0.952 g/cm³ |
| Melt Index | 0.40 g/10 min (190°C/2.16 kg) |
| Tensile Strength At Yield | 26 MPa |
| Tensile Strength At Break | 30 MPa |
| Elongation At Break | 600% |
| Flexural Modulus | 1200 MPa |
| Vicat Softening Point | 124°C |
| Shore D Hardness | 66 |
| Environmental Stress Crack Resistance | >1000 h |
| Brittleness Temperature | < -70°C |
| Deflection Temperature At 0 45 Mpa | 70°C |
As an accredited Dow HDPE DMDA-8904 NT 7 factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Dow HDPE DMDA-8904 NT 7 comes in 25 kg polyethylene-lined bags, palletized with 1,000 kg per pallet. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL): Dow HDPE DMDA-8904 NT 7, 25 kg bags, palletized, shrink-wrapped, securely stowed for ocean shipment. |
| Shipping | Dow HDPE DMDA-8904 NT 7 is a non-hazardous high-density polyethylene resin in pellet form. It ships in 25 kg bags, supersacks, or bulk trucks/railcars, palletized and wrapped. Keep dry, cool, away from sunlight and contamination. No dangerous goods documentation required. |
| Storage | Store Dow HDPE DMDA-8904 NT 7 in a cool, dry, well-ventilated area away from direct sunlight, heat, flames, and strong oxidizers. Keep original containers or bags closed, off the floor, and protected from moisture, dust, and contamination. Avoid prolonged UV exposure. Stack securely to prevent deformation or bursting. Keep away from incompatible materials. Follow the SDS and local regulations. |
| Shelf Life | Shelf life is typically 24 months when stored in original packaging under cool, dry conditions, away from direct sunlight. |
Extrusion blow molding of 220 L tight-head drums from DMDA-8904 NT 7 is performed on accumulator-head shuttle presses with clamp forces from 350 kN to 900 kN and extruder diameters in the 75 mm to 120 mm range. The melt temperature is maintained at 190–230 °C, and the parison programmer applies a wall-thickness profile from 2.0 mm at the pinch-off zone to 6.5 mm at the chime area to compensate for local stretch ratios and to maintain top-load strength under ISO 20848 stack storage. The high-load melt index of approximately 6.0 g/10 min under ASTM D1238 at 190 °C/21.6 kg permits filling of shot weights up to 10.5 kg without exceeding head pressure limits of 25–35 MPa, while the flow ratio I21/I2 above 80 provides sag resistance for parison lengths beyond 1,200 mm. The environmental stress cracking resistance of DMDA-8904 NT 7 under ASTM D1693 Condition B in 10% Igepal exceeds 1,000 h, which is the primary selection criterion for long-term storage of polar and aromatic hydrocarbon-based fills. The formulation for hazardous chemical transport uses 0.8–1.5 wt% hindered amine light stabilizer masterbatch and 0.05–0.15 wt% antistatic additive only when packaging flash-point solvents; regrind from trimmed pinch-off and reamed closures is reintroduced at up to 20 wt% only after the resulting drum passes the UN drop test at −18 °C and the hydraulic internal pressure test at 100 kPa for 10 min. Terminal product types are UN 1H1 closed-head and UN 1H2 open-head drums of 120 L, 200 L, and 220 L capacity for liquid chemicals, detergents, and non-flammable powders. Relevant compliance standards include UN Model Regulations Chapter 6.1, ADR P001, IMO IMDG Code, 49 CFR 178.504, ISO 20848 for stackability, and ASTM D256 for notched Izod impact at −30 °C, where the resin typically retains ductile failure above 6 kJ/m².
What Prevents Interlayer Delamination in Coextruded Barrier Fuel Tanks?
Plastic fuel tanks built with DMDA-8904 NT 7 employ a six-layer parison architecture in which the HDPE layers carry structural load and the ethylene-vinyl alcohol copolymer layer reduces hydrocarbon permeation. Delamination is controlled by matching the melt viscosity of the HDPE outer layer to the maleic anhydride-grafted polyethylene tie layer at a die temperature of 200–230 °C, and by holding the die temperature within ±5 °C across all six extruder streams so that the viscosity ratio at each interface remains below the level at which layer encapsulation or wavy interfacial flow occurs. The layer thickness distribution for a 60 L passenger vehicle tank is typically 12–18 wt% outer HDPE, 1.5–2.5 wt% tie/adhesive, 2.0–3.5 wt% ethylene-vinyl alcohol copolymer, 45–55 wt% regrind core, and 20–30 wt% inner conductive HDPE; the inner layer is compounded with conductive carbon black masterbatch to achieve a surface resistivity below 106 ohm/sq under SAE J1645. The production line uses a six-extruder coextrusion head with a 120 mm main extruder for the regrind core and 45–60 mm satellite extruders for the barrier and tie layers, a clamp force of 2,200–3,500 kN, and a blow pressure of 0.8–1.0 MPa. The resin density of 0.952 g/cm³ under ASTM D792 keeps tank mass within the manufacturer’s component weight envelope, while its notched Izod impact under ASTM D256 at −40 °C supports cold-impact requirements. Compliance anchors include EPA 40 CFR Part 86.1811 for evaporative emissions, CARB LEV III, Euro 6/VI evaporative emission limits, ECE R34 Annex 5 for fuel tank integrity, and SAE J1737 for laboratory hydrocarbon permeation testing. Published data for this specific coextruded fuel tank configuration is limited; the ethylene-vinyl alcohol layer thickness, adhesive grade, and regrind loading require line-specific qualification because DMDA-8904 NT 7 supplies the HDPE structural layers rather than the barrier function. Terminal product types are 50–85 L passenger car and light truck plastic fuel tanks, including low-permeation tanks for hybrid platforms where internal pressure fluctuates during canister purge cycles.
| Layer | Thickness allocation | Primary function | Critical control parameter |
|---|---|---|---|
| Outer HDPE | 12–18 wt% | Impact protection and stress distribution | Melt temperature 200–230 °C |
| Tie/adhesive | 1.5–2.5 wt% | Interlayer adhesion | Die setpoint held within ±5 °C |
| Ethylene-vinyl alcohol copolymer | 2.0–3.5 wt% | Hydrocarbon permeation barrier | Layer uniformity across parison circumference |
| Regrind core | 45–55 wt% | Material recovery and stiffness | Regrind loading validated by notched Izod at −40 °C under ASTM D256 |
| Inner conductive HDPE | 20–30 wt% | Electrostatic discharge | Surface resistivity below 106 ohm/sq per SAE J1645 |
Agrochemical packaging produced from DMDA-8904 NT 7 is dominated by wall-thickness uniformity challenges on shuttle blow molders with 38–65 mm grooved-feed extruders and 25–80 kN clamp force. The resin is processed at a melt temperature of 185–215 °C and blow pressure of 0.6–0.9 MPa; pre-blow delay is set between 0.3–1.0 s to stabilize the parison against sway before the mold closes, and post-cooling fixtures are applied to maintain thread dimensional stability under UN 31HZ2 closure torque tests. The required low-temperature drop performance is validated with 5 L and 10 L jerricans conditioned at −18 °C and dropped from a height of 1.2 m onto a steel plate. Formulation additions include 0.8–1.5 wt% hindered amine light stabilizer, 0.05–0.20 wt% phenolic antioxidant, and 1.5–2.5 wt% carbon black masterbatch for light-sensitive active ingredients; regrind from tail flash is limited to 10–15 wt% where the fill contains xylene, cyclohexanone, or ester-based emulsifiable concentrates, because these solvent classes reduce the environmental stress cracking resistance measured under ASTM D1693 Condition C. Standards governing the package are UN 31HZ2, ADR P001, IMDG Code, 40 CFR 156 for pesticide label packaging, and ISO 16101 for compatibility testing with liquid agrochemical formulations. Terminal product types include 500 mL, 1 L, 5 L, 10 L, and 20 L jerricans and narrow-mouth bottles used for organophosphate insecticides, pyrethroid formulations, and phenoxy herbicides.
IBC Inner Bottle Melt Rupture and UN 31HA1 Qualification Pressures
The critical failure mode in 1,000 L inner bottle blow molding is melt rupture at the pinch-off weld, not parison sag. DMDA-8904 NT 7 is processed on accumulator-head machines with a 120 mm extruder, 14–18 kg shot weight, and 2,000–3,500 kN clamp force; melt temperature is held at 190–220 °C and the parison die gap is profiled from 2.5 mm to 9.0 mm so that the pinch-off zone receives sufficient material without exceeding the cooling capacity of a mold chilled to 10–20 °C. Wall-thickness variation across a 1,250 mm parison is kept within ±3% by segment-based programming, and in-line ultrasonic thickness mapping is used to reject bottles with weld-line thinning below 2.0 mm. The formulation for UN 31HA1 qualification is 100% virgin DMDA-8904 NT 7, with 0.2–0.5 wt% fluoropolymer processing aid added only when surface melt fracture appears at high extrusion rates; no regrind is introduced into the inner wall unless the bottle passes the hydraulic internal pressure test at 100 kPa for 10 min and a 1.2 m drop test at −18 °C after 30 d of chemical exposure. Relevant compliance standards include UN 31HA1, ADR P001, IMDG Code, ISO 15867 for IBC design type, and ASTM D1998 for empty container stack life. Terminal product types are 1,000 L and 1,250 L composite IBC inner bottles for petrochemical intermediates, agricultural adjuvants, and liquid fertilizers.
| Packaging domain | Standard designation | Test condition | Acceptance threshold |
|---|---|---|---|
| Tight-head chemical drum | UN 1H1, 49 CFR 178.504 | Hydraulic internal pressure 100 kPa for 10 min; drop at −18 °C | No rupture, no leakage, no weld-line material failure |
| Agrochemical jerrican | UN 31HZ2, 40 CFR 156 | Drop from 1.2 m at −18 °C; closure torque per UN 31HZ2 | No rupture, no leakage, thread remains serviceable |
| Composite IBC inner bottle | UN 31HA1, ISO 15867 | Hydraulic 100 kPa for 10 min; drop 1.2 m at −18 °C after 30 d exposure | No rupture, no leakage, no wall thinning below 2.0 mm |
| Plastic fuel tank | EPA 40 CFR 86.1811, ECE R34 | Hydrocarbon permeation by SAE J1737; cold impact at −40 °C per ASTM D256 | Emission limit met; no brittle failure at weld or pinch-off zone |
Large Part Blow Molding Requires Melt Strength Above the Rheological Percolation Threshold
Marine holding tanks and agricultural sprayer tanks in the 100–500 L range are blow molded from DMDA-8904 NT 7 on single-station large-part machines with a 90 mm extruder and 24–36 kg shot capacity. The critical process conflict is maintaining sag resistance in a parison that can exceed 1,500 mm in free length; the resin’s high zero-shear viscosity and strain-hardening response delay draw-down only if die temperature is kept below 210 °C and the parison extrusion speed is matched to the mold close time of 8–15 s. Cooling time is governed by the square of the nominal wall thickness, so a 6.0 mm wall requires internal blow-air staging and post-mold cooling to hold total cycle time below 180 s while preventing post-mold shrinkage above 1.5% under ISO 294-4. Published extensional viscosity data for this specific grade is limited; line-specific melt strength measurement is required before using parison lengths above 1,500 mm. Formulation additions for outdoor service are 0.6–1.2 wt% carbon black masterbatch for UV stabilization, 0.1–0.3 wt% antioxidant, and 0.0–0.2 wt% antistatic additive when the tank stores flammable adjuvants; regrind from deflashed pinch-off and drilled fittings is limited to 15 wt% to maintain the environmental stress cracking resistance required for field service. Standards applied to these products include ISO 8096 for water storage in agriculture, NSF/ANSI 61 where potable-water contact is claimed by the fabricator, and ASTM D638 for tensile property verification at 23 °C and 50 mm/min. The terminal product types are 100 L, 200 L, 300 L, and 500 L horizontal sprayer tanks, marine holding tanks, and stationary chemical dosing tanks.
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- Dow HDPE DMDA-8904 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-8904 NT 7 is an unpigmented high-density polyethylene extrusion blow molding resin supplied in pellet form. The grade is specified for rigid container applications in which hydrostatic pressure, aggressive liquid contact, and compressive top load occur simultaneously. Manufacturer-published property data place the melt flow rate at 0.80 g/10 min under ASTM D1238 at 190°C/2.16 kg and solid density at 0.956 g/cm³ under ASTM D792. The resin is processed on shuttle, reciprocating screw, and accumulator-head extrusion blow molding lines for container volumes typically between 50 mL and 5 L. These melt flow and density values are used as incoming lot-acceptance parameters, but they do not replace application-specific validation of environmental stress crack resistance, pinch-off weld integrity, or top-load performance.
Commercial lot-to-lot melt flow variation for HDPE of this type can range within ± 0.05 g/10 min of the nominal value, while density variation is commonly within ± 0.001 g/cm³. Such shifts are small in absolute terms but can alter optimum cycle time and container wall distribution on high-cavity production molds. Statistical process control of bottle weight and wall thickness is therefore more sensitive to batch-to-batch variation than incoming melt flow testing alone.
Why Is DMDA-8904 NT 7 Chosen Over Bimodal HDPE Blow Molding Resins?
Selection between DMDA-8904 NT 7 and bimodal HDPE blow molding grades typically involves three processing trade-offs. The melt flow rate of 0.80 g/10 min is higher than that of many high-molecular-weight bimodal blow molding resins, which frequently fall below 0.30 g/10 min at the same temperature. The higher melt flow rate lowers extruder torque and shortens plastication time in 60 mm to 90 mm single-screw extruders with 24:1 to 30:1 length-to-diameter barrels.
The molecular architecture of DMDA-8904 NT 7 generally produces lower die swell than bimodal high-molecular-weight HDPE grades. Low die swell assists parison dimensional control in thin-wall containers but reduces parison melt strength for very large partisons above 5 L. A density of 0.956 g/cm³ also confers higher flexural modulus than lower-density HDPE bottle grades in the 0.949–0.952 g/cm³ range, but higher density can reduce low-temperature impact resistance when wall thickness is reduced below 0.5 mm. The grade is accordingly positioned for containers requiring stiffness and chemical resistance rather than for large industrial drums, fuel tanks, or deeply drawn hollow parts requiring maximum melt strength.
On continuous shuttle extrusion blow molding lines, barrel temperature profiles are commonly set from 170°C at the feed throat to 210°C at the die head, with a target melt temperature of 200–220°C. At screw speeds above 90 rpm on a 60 mm grooved-feed extruder, shear heating can raise melt temperature above 220°C, producing parison sag and nonuniform sidewall thickness in containers with 0.6–1.0 mm walls. For grooved-feed single-screw machines with water-cooled feed sections, back pressure is typically maintained between 5 MPa and 15 MPa to compact the solid bed. Screws with barrier flights and Maddock mixing sections are used to reduce melt temperature gradients across the channel.
Mold temperatures between 10°C and 30°C are maintained to freeze the pinch-off weld before part ejection. Blow air pressure is normally set between 0.6 MPa and 1.0 MPa, measured at the blow pin, to expand the parison without producing flash or inner-surface roughness. Because HDPE is not hygroscopic, pre-drying is generally unnecessary. Pellets exposed to ambient humidity above 60% RH should nevertheless be stored in closed containers or hoppers to avoid surface moisture above 0.05 wt%, which can produce surface splay in bottle sidewalls.
Top-Load Mechanics in Frozen-Wall HDPE Bottles
| Property | Test method | Typical value |
|---|---|---|
| Melt flow rate | ASTM D1238 | 0.80 g/10 min |
| Density | ASTM D792 | 0.956 g/cm³ |
| Tensile stress at yield | ASTM D638 | 30 MPa |
| Flexural modulus, 1% secant | ASTM D790 | 1,380 MPa |
| Vicat softening temperature | ASTM D1525 | 127°C |
Container top-load is measured under ASTM D2659 or by customer-defined compression plates at a displacement rate of 12.5 mm/min. For a 1 L bottle molded at 30 g weight, top-load capacity depends on sidewall geometry and material modulus. The reported flexural modulus near 1,380 MPa provides higher resistance to panel deformation than HDPE grades with density near 0.950 g/cm³. However, empty-container top-load failure frequently occurs at the pinch-off weld when clamp force is insufficient to compress the parison lands. Pinch-off weld thickness should be at least 1.5 times the adjacent wall thickness for aggressive liquid formulations, with land width maintained between 0.5 mm and 2.0 mm depending on container size.
Cooling-limited cycle time for HDPE blow molded containers is governed by heat transfer through the mold wall. With chilled water at 7–12°C, cycle times for a 500 mL bottle weighing 20 g are typically 8–14 s, whereas a 5 L container weighing 200 g can require 45–75 s. Faster cycles are possible with high-thermal-conductivity aluminum tooling but may increase shrinkage variation. Dimensional readings are made after conditioning samples for 24 h at 23 ± 2°C and 50 ± 10% RH.
A 100% Igepal CO-630 test under ASTM D1693 Condition B is the most commonly cited environmental stress crack resistance method for rigid HDPE containers. Published typical values for DMDA-8904 NT 7 are often expressed as F50 > 300 h, meaning more than half of specimens survive beyond that interval without visible cracking. The test is conducted at 50°C with a notched specimen bent to a controlled strain. While this result supports use with household cleaners, detergents, and water-based formulations, it does not guarantee compatibility with solvent-based automotive fluids or oxidizing acids.
When 1,000-Hour ESCR Testing Is Required for Aggressive Household Chemistries
Some retail specifications impose a 1,000 h environmental stress crack resistance threshold under ASTM D1693 Condition B or ISO 22088-2. Under these conditions, test variability becomes significant because notch depth and bent-specimen stress are sensitive to specimen preparation. Direct ranking between HDPE grades should not be made unless a common notching blade, controlled radius, and identical stock temperature are used. In DMDA-8904 NT 7, the combination of density 0.956 g/cm³ and rapid blow mold cooling produces ESCR values that vary with wall thickness and cooling rate. Rapidly cooled sidewalls below 0.6 mm can show different crack kinetics from the compression-molded plaques used for datasheet values.
When a 1,000 h requirement must be verified, testing should be performed on bottles sampled across a multi-cavity mold and across multiple production lots. Batch-to-batch catalyst residue and comonomer distribution can shift crack initiation times even when melt flow rate and density remain within specification. For solvent-based fluids, coupon immersion testing at 40°C for 14 days or at 60°C for 30 days is required to measure mass uptake and tensile property retention according to ISO 175 and ASTM D543. Published data for DMDA-8904 NT 7 in concentrated solvent mixtures is limited; qualification therefore requires chemical compatibility testing on the finished container, not reliance on resin ESCR alone.
DMDA-8904 NT 7 is a natural, unpigmented resin. Food-contact status must be confirmed through a current manufacturer compliance letter; olefin polymers are referenced under 21 CFR 177.1520 for applicable indirect food-contact uses, but specific end-use limitations and conditions of use require fabricator validation. Heavy metal and hazardous substance restrictions are typically assessed against EU REACH Candidate List obligations and Directive 2011/65/EU RoHS articles. The base resin does not contain intentionally added UV stabilizer or antistatic additive. Containers exposed to outdoor storage require carbon black, UV stabilizer masterbatch, or opaque colorant in the final formulation. Users should verify that the selected colorant or processing aid masterbatch does not reduce environmental stress crack resistance or regulatory compliance.
Injection Molding Substitution Is Not Recommended
Compared with HDPE injection molding grades with melt flow rates above 4 g/10 min, DMDA-8904 NT 7 would exhibit insufficient flow for thin-wall injection molding and should not be substituted into injection mold tools without rheological verification. Its molecular weight is optimized for parison integrity and pinch-off weld formation rather than for filling long flow-length cores. Conversely, substituting a lower-molecular-weight injection grade into extrusion blow molding would reduce parison melt strength and increase reject rates from hole formation and nonuniform wall distribution.
For accumulator-head machines, die land length-to-gap ratio is normally maintained between 10:1 and 20:1 to generate sufficient head pressure and reduce weld lines in the parison. Excessively high shear in the die land can produce melt fracture and surface roughness, particularly at wall thicknesses below 0.5 mm. Surface treatment for printing and labeling by flame or corona should raise surface energy above 38 mN/m measured by ISO 8296, because nonpolar HDPE surfaces otherwise provide poor ink adhesion. These processing limits form part of the operational boundary for this grade and must be addressed before commercialization of any new container design.
