LDPE INJ (Injection moulding grade)
Grade
ASTM D1248 Type I · ISO PE-LD
High-MFR, lower-molecular-weight resin for thin-wall soft mouldings such as closures, liner caps and squeeze parts.
Values for the INJ condition
Other LDPE grades and fills
LDPE is listed in 7 conditions; see the grade overview at LDPE.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Closed-cell LDPE foam | Chemically or physically blown closed-cell foam for protective packaging, gaskets and thermal insulation. | 0.35 | 100 | ||
Extrusion coating / lamination grade | Broad-MWD resin for high-speed coating of paper, board and foil; chosen for neck-in control and hot-tack adhesion. | 9 | 11 | 400 | 45 Shore D |
INJThis page Injection moulding grade | High-MFR, lower-molecular-weight resin for thin-wall soft mouldings such as closures, liner caps and squeeze parts. | 10 | 10 | 200 | 46 Shore D |
FR V-0 | Use where UL 94 V-0/V-2 or low-smoke halogen-free cable compounds are required; heavy filler loading cuts elongation sharply. | 10 | 10 | 150 | 52 Shore D |
Carbon-black pigmented (2–2.5% CB) grade | Best low-cost outdoor durability — 2.5% well-dispersed carbon black for pipe sleeving, geomembrane and cable jacketing. | 10 | 11 | 400 | 48 Shore D |
Antistatic / conductive carbon-filled grade | Carbon-black or antistat-loaded compound for electronics packaging film, explosive-atmosphere liners and cable semicon layers. | 11 | 12 | 250 | 50 Shore D |
Cross-linked LDPE | Cross-linked network for LV/MV cable insulation and heat-shrink; raises continuous rating to ~90 °C and kills stress cracking, but the cured part cannot be remelted. | 17 | 450 | 50 Shore D |
What is LDPE INJ?
LDPE INJ is LDPE in the INJ grade — high-MFR, lower-molecular-weight resin for thin-wall soft mouldings such as closures, liner caps and squeeze parts. LDPE INJ has a yield strength of 10 MPa (1.38 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 92% of polymer grades. Elongation at break is 200% and the elastic modulus is 0.2 GPa (0.029 Msi). LDPE INJ has a density of 0.92 g/cm³ (0.0333 lb/in³), lighter than 79% of polymer grades. Its glass-transition temperature is -110°C (-166 °F).
Advantages
- Low moisture uptake — 0.01%, better than 97% of polymer grades
- Readily welded — 90/100, better than 94% of polymer grades
- Low embodied carbon — 2.1 kg CO₂/kg, better than 94% of polymer grades
- Forms and bends easily — 90/100, better than 91% of polymer grades
- Conducts heat well — 0.33 W/m·K (0.191 BTU/hr·ft·°F), better than 89% of polymer grades
Limitations
- Low strength — 10 MPa (1.38 ksi), worse than 92% of polymer grades
- Degrades in UV without stabilisers — 20/100, worse than 88% of polymer grades
- High mold shrinkage — 2.2%, worse than 87% of polymer grades
- Hard to polish — 30/100, worse than 82% of polymer grades
- Difficult to machine — 45/100, worse than 78% of polymer grades
LDPE INJ properties
Typical room-temperature values for LDPE INJ; 27 are specific to this condition. Other listed values are LDPE reference data and may not represent this condition. Bars are the position among polymer grades.
Physical7
LDPE INJ has a density of 0.92 g/cm³ (0.0333 lb/in³), lighter than 79% of polymer grades. Its glass-transition temperature is -110°C (-166 °F).
Mechanical17
LDPE INJ has a yield strength of 10 MPa (1.38 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 92% of polymer grades. Elongation at break is 200% and the elastic modulus is 0.2 GPa (0.029 Msi).
Thermal11
LDPE INJ is rated for continuous service to 70°C (158 °F). It conducts heat at 0.33 W/m·K (0.191 BTU/hr·ft·°F), better than 89% of polymer grades. Thermal expansion is 190 µm/m·K (105.6 µin/in·°F).
Electrical7
LDPE INJ is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of LDPE INJ takes about 80 MJ of energy and emits 2.1 kg of CO₂ — less than 85% of polymer grades. Typical recycled content is 10%.
Manufacturability8
LDPE INJ's machinability is fair (45/100, worse than 78% of polymer grades); weldability excellent (90/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with LDPE INJ
Is LDPE easy to machine?
Cuts easily but is gummy and springs back — use very sharp positive-rake single-flute tools, high speed, low feed pressure, air blast, and expect poor tolerance hold (>0.2 mm) plus large thermal expansion.
Can LDPE be welded?
Excellent thermoplastic weldability: heat sealing, impulse, hot-plate, hot-gas and extrusion welding with LDPE/LLDPE rod; adhesive bonding needs corona, flame or plasma surface treatment.
Can LDPE be formed, bent or molded?
Very easy flow at 160–230 °C melt, 20–50 °C mould, low injection pressure; allow 1.5–4% shrinkage with strong direction dependence and design generous draft and thick-to-thin gating to avoid voids and sink.
What surface finishes work on LDPE?
Cannot be plated or painted without pre-treatment; use corona/flame treatment (≥38 dyn/cm) before printing, or in-mould colour, laser marking and hot stamping instead.
LDPE chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| antioxidant / process stabilizer (hinder | 0.02 – 0.3 | 0.1 |
| slip & antiblock (erucamide, silica) — fOmitted in injection and food-critical grades | 0 – 1 | 0.3 |
| ethylene (branched homopolymer, C2H4 repHigh-pressure free-radical polymer; 20–40 short-chain branches + long-chain branching per 1000 C; crystallinity 40–55% | ≥ 98 (balance) |
LDPE INJ — frequently asked
What is LDPE INJ used for?
LDPE INJ is typically used for squeeze bottles, flexible tubing and hose, packaging film and drum liners, bottle cap liners and gaskets, wire and cable insulation and extrusion coating on paperboard. In short: flexible; low cost.
What is the yield strength of LDPE INJ?
LDPE INJ has a typical yield strength of 10 MPa (1.38 ksi) and a tensile strength of 10 MPa (1.45 ksi) — weaker than 92% of polymer grades. Strength varies by condition: see the 7 listed tempers.
Is LDPE INJ easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 78% of polymer grades). Cuts easily but is gummy and springs back — use very sharp positive-rake single-flute tools, high speed, low feed pressure, air blast, and expect poor tolerance hold (>0.2 mm) plus large thermal expansion.
Can LDPE INJ be welded?
Yes — weldability is rated excellent (90/100). Excellent thermoplastic weldability: heat sealing, impulse, hot-plate, hot-gas and extrusion welding with LDPE/LLDPE rod; adhesive bonding needs corona, flame or plasma surface treatment.
What surface finishes work on LDPE INJ?
Cannot be plated or painted without pre-treatment; use corona/flame treatment (≥38 dyn/cm) before printing, or in-mould colour, laser marking and hot stamping instead.
Can LDPE INJ be formed, bent or molded?
Very easy flow at 160–230 °C melt, 20–50 °C mould, low injection pressure; allow 1.5–4% shrinkage with strong direction dependence and design generous draft and thick-to-thin gating to avoid voids and sink.
What is the maximum service temperature of LDPE INJ?
LDPE INJ is rated for continuous use to about 70°C (158 °F), and briefly to 90°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in LDPE INJ?
Yes — LDPE INJ is available for sheet metal and injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D4976 — Standard Specification for Polyethylene Plastics Molding and Extrusion Materials — ASTM International (2020)
- ISO 1872-1/-2 — Plastics: Polyethylene (PE) moulding and extrusion materials — ISO (2015)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
- CAMPUS / UL Prospector polyethylene datasets — CWFG / UL Solutions (2024)
- LDPE film and injection grade datasheets — Dow / ExxonMobil / SABIC / (2024)
- Eco-profile: Low Density Polyethylene (LDPE) — PlasticsEurope (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.