Dow VLDPE DFDB-1085 NT is an ethylene-octene copolymer with a nominal density of 0.885 g/cm³ (ASTM D792-20) and a melt index of 0.80 g/10 min (ASTM D1238-20, 190 °C/2.16 kg). The low density reduces flexural modulus and heat seal initiation temperature while retaining sufficient shear viscosity for single-screw and twin-screw extrusion. The following applications are grouped by manufacturing route and not by generic end-market category.

A three-layer cast film line using a 0.5 mm die gap and 2800 mm die width extrudes DFDB-1085 NT as a 12–18 µm sealant skin over a polypropylene core. Die temperature is set at 220–240 °C; because the resin has a melt index of 0.80 g/10 min, die pressure remains between 120–180 bar and neck-in is held below 8% of die width by adjusting the air knife gap and die land length. Chill roll temperature is fixed at 18–22 °C, with a maximum of 25 °C to avoid wound-roll blocking. The formulation contains 92–96 wt% DFDB-1085 NT, 2–4 wt% LDPE for neck-in control, 1–2 wt% synthetic silica antiblock masterbatch, and 0.05–0.1 wt% erucamide slip masterbatch. Seal initiation is determined on a laboratory heat sealer at 0.3 MPa jaw pressure and 0.5 s dwell; seal strength above 8 N/15 mm is reached at jaw temperatures of 100–110 °C (ASTM F88/F88M-21). This is 15–20 °C lower than conventional LLDPE sealant skins and allows faster form-fill-seal cycling. Frozen vegetable pouches and snack films are conditioned for 48 h at -30 °C and tested by ASTM D1709-16a method A for dart impact retention. Food-contact compliance is verified under FDA 21 CFR 177.1520(c) for olefin polymers and EU Regulation (EC) No 10/2011, with overall migration below 10 mg/dm² using aqueous food simulant A and fatty food simulant D2.

What Limits Filler Loading in Halogen-Free Flame-Retardant Insulation Based on DFDB-1085 NT?

DFDB-1085 NT is selected for low-voltage single-core cable insulation because the 0.885 g/cm³ matrix accepts high loadings of precipitated alumina trihydrate without the low-temperature embrittlement observed in LDPE-based halogen-free flame-retardant compounds. A dense compound is built on 100 phr VLDPE with 150 phr precipitated ATH having a median particle size of 1.3–1.8 µm, 8 phr zinc borate, 4 phr silicone masterbatch, 1.5 phr hindered phenolic stabilizer masterbatch, and 0.3 phr maleic anhydride-grafted PE compatibilizer. The lubricant-containing masterbatch is not added at the hopper throat; it is side-fed into the melt to avoid slip on the feed screw. Mixing is carried out on a co-rotating twin-screw extruder with 44:1 L/D, 65 mm screw diameter, and 14 barrel zones. The barrel profile is 140 °C in the feed zone, 160–170 °C in the kneading blocks, 175 ± 5 °C in the final mixing zone, and 180 °C at the die. Screw speed is 280–320 rpm; melt pressure upstream of the screen changer is held below 160 bar. At filler levels above 60 wt%, torque rises by 12–18% and melt temperature overshoots above 190 °C, initiating hydrate decomposition. Above 205 °C, the strand foams and pellet surface roughness appears; the strand bath temperature must remain below 25 °C to avoid cutting-line adhesion. ATH moisture content above 0.15 wt% at hopper entry blocks the vacuum vent port on the same 65 mm line and triggers melt pressure oscillation. Pre-drying in a desiccant dryer at 60 °C for 4 h is required when ambient relative humidity exceeds 60%.

Finished insulation is tested under IEC 60332-1-2 for vertical flame spread, IEC 60754-2 for halogen acid gas evolution, and IEC 61034-2 for smoke density. Tensile specimens are cut as ISO 527-2 type 5A and conditioned at 23 ± 2 °C and 50 ± 5% RH for 24 h. High-filler compounds typically show elongation at break above 150% only when the extrudate is cooled in a water bath below 25 °C. Oxygen index is measured by ISO 4589-2; values below 32% O₂ usually indicate insufficient ATH dispersion or partial filler dehydroxylation. The same compound should not be combined with amine-based stabilizers because amine functionality accelerates surface hydrolysis of ATH and can increase water release at processing temperatures. Electric vehicle charging cable constructions are evaluated under EN 50620; polymer identity and formulation must remain traceable for the 10-year durability requirement. Published data for DFDB-1085 NT at ATH loading above 62 wt% is limited; extruder trials above that threshold require a 70 mm screw or a side-fed filler profile to maintain pellet quality.

In a 25 mm single-screw extruder with 24:1 L/D, DFDB-1085 NT is extruded through a crosshead die into low-durometer tubing with wall thickness 0.8–2.0 mm and outer diameter 6–12 mm. Barrel temperatures are profiled from 150 °C at the hopper to 180 °C at the die; melt temperature is held below 190 °C so the soft extrudate retains a circular cross-section in the vacuum sizer. Vacuum sizing uses 10 kPa negative pressure and water at 20 °C. The compound is 100 phr DFDB-1085 NT with 0.2 phr hindered phenolic antioxidant masterbatch and 0.1 phr fluoroelastomer-free process aid. No monomeric plasticizer is used, which avoids plasticizer migration into pumped fluids. Hardness is measured as 82–88 Shore A (ISO 868) at 23 °C; tensile elongation at break is determined by ISO 527-2 type 5A. For industrial fluid transfer, raw material contact with food is evaluated under FDA 21 CFR 177.1520 and EU Regulation (EC) No 10/2011; for a finished medical device, cytotoxicity testing under ISO 10993-5 and a hemocompatibility assessment are required on the final sterilized article. Published data for a DFDB-1085 NT-only medical tubing formulation without additional stabilizers is limited. Terminal uses are peristaltic pump inserts, irrigation tubing, and low-pressure hydraulic return lines.

When Cold-Chain Containers Require a Secondary Ethylene-Octene Impact Modifier

Impact-modified polypropylene for injection-molded cold-chain containers uses DFDB-1085 NT as a secondary elastomer phase to improve notched impact retention at -30 °C while keeping melt-flow index above 12 g/10 min (ISO 1133-1:2022, 230 °C/2.16 kg). The compound is produced on a co-rotating twin-screw extruder with 40:1 L/D; PP random copolymer is fed in the first barrel, DFDB-1085 NT is side-fed at 15–25 wt% after the initial melt section, and a phenolic-phosphite stabilizer blend is metered at 0.1 wt% through the side feeder. Barrel temperatures are 200–230 °C, with a die temperature of 210 °C. Injection molding uses a barrel profile of 210–240 °C, mold temperature of 20–40 °C, and hold pressure of 50–70 MPa on a clamp force of 12,000 kN. Published data for DFDB-1085 NT in this exact PP random copolymer formulation is limited; comparative compounding with an equivalent 0.885 g/cm³ ethylene-octene modifier typically raises ISO 180/A notched Izod impact at -30 °C from 3–5 kJ/m² to 9–14 kJ/m² at 18–22 wt% addition. Flexural modulus (ISO 178) falls from approximately 1,150 MPa to 820 MPa. Above 25 wt%, phase inversion creates surface tack, sink marks on ribs, and screw feed-zone fouling. Terminal parts are cold-chain crates, freezer door liners, and agricultural tote lids, where the low glass transition temperature of the octene branches delays embrittlement.

Chemical foaming of DFDB-1085 NT with azodicarbonamide masterbatch at 1.5–2.5 wt% is used to extrude closed-cell pipe insulation with density 45–80 kg/m³. A single-screw extruder with 30:1 L/D and an annular die gap of 1.0 mm is configured with a temperature profile from 130 °C in the feed zone to 165 °C at the die. The gas decomposition temperature of azodicarbonamide is 205 °C; therefore any barrel zone above 190 °C is restricted to the final 20% of screw length, and melt residence time above that threshold is kept below 60 s to prevent premature cell coalescence. Open-cell content is measured by ASTM D6226 and kept below 15% for moisture-resistant pipe insulation. Compression set at 23 °C is measured by ISO 815 after 24 h recovery; water absorption is evaluated by ASTM D1056 and held below 5%. Thermal conductivity data for this exact VLDPE foam density range is limited; building product evaluation follows EN 14313 for factory-made flexible polyethylene foam insulation. Terminal products are HVAC line insulation, refrigeration piping covers, and automotive gasket strips where elongation above 200% (ISO 527-2) and low-temperature flexibility at -40 °C are required.