On a 70 mm single-screw blown-film extruder fitted with a 30:1 L/D barrier screw and a 350 mm monolayer die, Braskem LF0720/21AF is processed into heavy-duty form-fill-seal liners for 25 kg granular fertiliser sacks. The resin is a blown-film extrusion linear low density polyethylene with nominal density 0.920 g/cm³ (ASTM D792) and nominal melt flow rate 1.0 g/10 min (ASTM D1238, 190 °C/2.16 kg). A starting formulation for this sector is 75 wt% LF0720/21AF, 20 wt% high-pressure LDPE with MFR 0.3 g/10 min, and 5 wt% titanium dioxide masterbatch. The high-pressure LDPE phase raises bubble stability at elevated frost line positions, while the masterbatch lowers light transmission for fertiliser contact labelling. Die gap is set at 1.8 mm, blow-up ratio at 2.5:1, melt temperature at 205–215 °C, and frost line height at 8–10 die diameters. Film gauge is controlled at 60 µm. On this equipment, die pressure remains below 330 bar, and output is limited by bubble cooling rather than screw recovery. The terminal inner liner is pre-converted into tubular rollstock and sealed on vertical form-fill-seal equipment. Converter-side hot-tack and seal-strength checks are based on ASTM F1921; a minimum seal strength of 9 N/15 mm is commonly specified for pest-proof and moisture-tight wicket filling. Compliance for fertiliser contact is evaluated under applicable national packaging legislation, with REACH Regulation (EC) No 1907/2006 applying to European Union import. Batch-to-batch variance in dart impact at 60 µm is controlled by monitoring incoming resin MFR and density rather than relying on film appearance alone.

What Limits Outdoor Service Life in Silage Cover Film?

The service life of a bunker silo cover is controlled by UV stabiliser dispersion, film gauge, and mechanical damage during installation. Braskem LF0720/21AF is formulated as a black monolayer film at 125 µm with a starting blend of 96 wt% resin, 2 wt% carbon black masterbatch, and 2 wt% hindered amine light stabiliser masterbatch. The masterbatch carrier is selected to be compatible with LLDPE; incompatible carriers lower carbon black dispersion and create premature film fibrillation at fold lines. Processing is carried out on a 90 mm single-screw extruder with 30:1 L/D and a 450 mm die. Die gap is 2.0 mm, blow-up ratio is 2.8:1, melt temperature is 200–210 °C, and frost line height is 10–12 die diameters to stabilise the larger bubble. The finished bunker cover is perforation-free and is secured with sandbags or tires. Accelerated weathering is checked according to ASTM G154 Cycle 1; a common acceptance criterion is 70% retained elongation at break after 500 h, though published data for this specific formulation is limited. Compliance is industrial and agricultural, not food contact. Outdoor exposure beyond 12 months is not recommended unless gauge is increased above 150 µm, because continuous UV irradiation and silage acids embrittle the film near the soil interface.

Coextruded frozen-food webs operating at −40 °C need sealant layers that retain impact resistance after surface frosting and distribution vibration. LF0720/21AF is placed in the sealant layer of a three-layer structure at 35 wt%, with a 45 wt% high-α-olefin LLDPE core and a 20 wt% high-pressure LDPE outer layer. The three-layer die measures 300 mm, with 1.6 mm die gap, 2.2:1 blow-up ratio, and 215 °C melt temperature across all layers; line output is held near 85 kg/h to control gauge profile. Finished film gauge is 50 µm. Cold-temperature dart impact is measured under ASTM D1709 Method A after conditioning at −18 °C for 24 h; a specification of 140 g or higher is frequently set for vegetable pillow pouches, but published data for this specific layer structure is limited and must be verified on the converter line. Heat seal initiation is tested on a laboratory jaw sealer at 0.7 N/mm² pressure and 1 s dwell; LLDPE sealant layers of this melt index typically initiate between 105 °C and 115 °C. Compliance is governed by FDA 21 CFR 177.1520 for olefin polymers and EU Regulation (EU) No 10/2011, with overall migration below 10 mg/dm² under simulated frozen-food conditions. The terminal article is a printed pillow pouch for free-flow frozen vegetables, where the sealant web provides low-temperature puncture resistance and controlled seal separation on packaging lines.

Stretch Hood Tear Propagation Across Palletized Construction Materials

Palletized construction materials create repeated low-speed puncture events at the bottom edges of the load. LF0720/21AF is used as the majority phase in a 180 µm monolayer stretch hood film blended with 15 wt% metallocene-catalysed LLDPE to lift puncture resistance without sacrificing elastic recovery. The line is a 100 mm extruder with 35:1 L/D and a 600 mm die. Die gap is 2.2 mm, blow-up ratio is 2.5:1, melt temperature is 215–225 °C, and the bubble is run in a high-stalk configuration to increase machine-direction orientation. Terminal stretch hoods are wound on 300 mm cores and applied on automatic pallet hooders. Tensile properties are checked according to ASTM D882, and tear propagation is measured by ASTM D1922; converters commonly define transverse-direction Elmendorf tear acceptance on a line-specific basis because tear anisotropy shifts with high-stalk frost line height. Compliance is industrial packaging; direct food contact is not claimed unless migration testing under EU Regulation (EU) No 10/2011 is completed by the converter. The operational boundary is cold stretching; at application temperatures below 5 °C, converter trials are required to set pallet hooder pre-stretch force and avoid film fracture at pallet corners.

When a 150 µm Vapour Barrier Membrane Replaces LDPE in Crawl-Space Installation

A 150 µm black membrane intended for crawl-space installation must combine low water vapour transmission with puncture resistance during aggregate placement. Braskem LF0720/21AF is formulated with 2.5 wt% carbon black masterbatch and 1 wt% processing aid masterbatch, then blown on a 75 mm extruder with 30:1 L/D, a 400 mm die, 2.0 mm die gap, 2.6:1 blow-up ratio, and 205 °C melt temperature. Water vapour permeance is measured by ASTM E96 Method B at 23 °C and 50% relative humidity; a 150 µm LLDPE film of 0.920 g/cm³ density typically reports permeance below 0.15 perm, but converter certification is required. Puncture resistance during installation is evaluated by ASTM D1709 Method A after film conditioning at 23 °C. The membrane is installed as a loose-laid sheet with 150 mm overlap; acrylic pressure-sensitive tape is recommended for lap seams. Compliance is building-code driven and may require ASTM E84 surface burning classification when the film is installed in a conditioned crawl space. LF0720/21AF contains no flame-retardant additive; a flame-retardant masterbatch can be introduced but commonly reduces tensile elongation and should be qualified with ASTM D882 before specification.

Lamination Sealant Webs and Heat-Seal Strength Decay

Lamination converters using solventless polyurethane adhesives require a sealant web that does not block at winding temperatures and maintains heat-seal strength after adhesive cure. LF0720/21AF is downgauged to 30 µm at 2.0:1 blow-up ratio and 1.2 mm die gap, with melt temperature 210 °C. The extruder is a 55 mm line with 28:1 L/D and a 250 mm die. No slip additive is added to this structure; antiblock is dosed at 0.15 wt% to avoid interference with ink adhesion after lamination. Seal strength is evaluated after lamination to 12 µm polyester film using ASTM F88 with a 25 mm strip at 180 °C, 0.5 s dwell, and 0.4 N/mm² pressure. The sealant web should reach stable peel strength above 12 N/25 mm after 48 h adhesive cure; early testing at 4 h can show reduced values due to undercured polyurethane. Compliance for dry food contact follows EU Regulation (EU) No 10/2011, with migration testing under test condition OM1. Terminal article is a stand-up pouch for powdered beverage mixes, in which the sealant layer provides burst resistance at the gusset corners.