Low-density polyethylene (LDPE) is specified by melt mass-flow rate (MFR) under ISO 1133-1:2022 at 190 °C/2.16 kg, nominal density under ASTM D1505, and additive package variables such as slip, antiblock, and antioxidant loading. A conversion from PTTGC to SABIC LDPE—or the reverse—is not a direct resin exchange because the two suppliers may differ in long-chain branching distribution, gel level, and molecular weight polydispersity even when nominal MFR and density overlap. The comparison PTTGC vs SABIC LDPE: Price, Lead Time and Grade Mapping therefore requires evaluation of three separate vectors: landed cost, delivery lead time, and grade translation by processing window. Datasheet-only substitution is insufficient for blown film lines running thin-gauge film at high throughput, especially where bubble stability, heat-seal initiation, and melt strength control the operating window.

Resin acceptance testing for film-grade LDPE should include ASTM D1238 MFR, ASTM D1505 density, ASTM D882 tensile modulus and elongation, and ASTM D1709 dart impact. These tests describe the resin in the standardized state but do not quantify melt strength, neck-in, or heat-seal initiation. A processor performing a drop-in substitution should first run a standardized trial on a blown film line with a die gap of 1.2–1.8 mm, blow-up ratio between 2.0 and 3.0, and melt temperature from 160 °C to 190 °C. Bubble stability is the controlling response variable; MFR matching alone does not predict performance on a high-speed monolayer line.

What Supply-Chain Variables Differentiate PTTGC and SABIC LDPE Deliveries?

Price comparison for PTTGC and SABIC LDPE is best performed on a total landed cost basis rather than on a single CFR or FOB number. PTTGC supplies LDPE from Map Ta Phut, Thailand, to ASEAN converters. Domestic lead time by truck is typically 1–7 days, while intra-ASEAN deliveries through Laem Chabang to Vietnam, Malaysia, Indonesia, and the Philippines generally require 7–14 days depending customs clearance and feeder vessel frequency. SABIC LDPE from Saudi Arabian ports such as Jubail or Yanbu to Southeast Asian main ports typically requires 18–30 days for deep-sea container service, with an additional 3–5 days for inland trucking and port deconsolidation. On the Indian subcontinent, SABIC deliveries may be shorter than PTTGC because of direct Arabian Sea routing, while PTTGC may use transshipment through Singapore or Port Klang. Specific spot price differentials are not stable enough to state a single number; purchase contracts should be indexed to ICIS or S&P Global Commodity Insights weekly CFR assessments, plus monomer and freight adjustments.

Working capital exposure changes directly with lead time. At a consumption rate of 500 t/month and a notional CFR landed cost of 1,100 USD/t, a 30-day SABIC transit pipeline carries roughly 500 t of in-transit inventory, compared with 7–14 days for PTTGC intra-ASEAN supply. This difference affects warehouse occupancy, letter of credit tenor, and supply-chain safety stock. The comparison is therefore not only per-tonne price but also cash-to-cash cycle time, demurrage risk, and minimum order quantity constraints at the converter warehouse.

Blown Film LDPE Grade Translation by Melt Index and Density Bands

Grade mapping between PTTGC and SABIC LDPE should be performed first by normalizing MFR and density, then by matching additive functions such as slip, antiblock, and processing aid. A one-to-one grade equivalence is valid only after the converter confirms that the supplier technical datasheets list the same additive package and that the molecular weight distribution does not shift bubble stability outside the operating window. The table below provides a conservative grade-space mapping. It is not an exhaustive equivalence list.

A film conversion trial should be designed as a paired comparison on the same blown film line rather than as a sequential trial with residual pellet contamination. The extruder should be purged with the incoming resin for at least 30 min before data collection. Output rate, bubble diameter, frost-line height, extruder backpressure, motor load, film thickness, and dart impact should be recorded using calibrated gauges traceable to ISO 9001. The changeover protocol should not alter either barrier screw speed or temperature settings until baseline stability is documented. On a high-output blown film line with a 65 mm extruder and 30:1 L/D, the processor typically controls melt temperature between 160 °C and 190 °C, frost-line height between 300 mm and 700 mm, and haul-off speed to a target film thickness of 40–80 µm. A change from PTTGC LD2420D to SABIC LDPE 2101 should be validated by plateau trials at fixed extruder barrel profiles and not by a single datasheet MFR match.

Molecular architecture is a residual variable in LDPE grade mapping. The high-pressure autoclave or tubular reactor configuration, chain-transfer agent type, and reactor pressure profile influence long-chain branching frequency. Two LDPE grades with identical 2.0 g/10 min MFR can show measurable differences in extensional viscosity and strain hardening. Published data comparing the full viscoelastic fingerprint of PTTGC and SABIC LDPE film grades is limited, so a capillary rheometry test under ISO 11443 at apparent shear rates from 100 s⁻¹ to 1,000 s⁻¹ is recommended when a converter moves from one supplier to the other. If capillary viscosity at 1,000 s⁻¹ deviates more than 10%, a new screw-speed setpoint or temperature profile is required to maintain gauge uniformity.

When Extrusion Coating Replaces Blown Film in High-Line-Speed LDPE Operations

Extrusion coating lines running 12–15 µm LDPE coatings at 250–320 m/min require melt strength and draw-down behaviour that does not appear directly on a standard datasheet. PTTGC and SABIC extrusion-coating LDPE grades with nominal MFR in the 3.5–7.5 g/10 min range are matched by processing behaviour, not by grade code equivalency. The trade-off is neck-in and heat seal initiation. Neck-in measured on a 300 mm slot die at 300 m/min ranks the resins for a given substrate and air-gap setting. Without that measurement, the grade-mapping is provisional. The processor should also monitor gel count and melt curtain stability because LDPE produced with different reactor technologies may differ in gel population and draw resonance onset.

For food-contact LDPE converters, compliance verification is separate from grade mapping. Selected PTTGC and SABIC LDPE film grades may be supplied with food-contact compliance statements under FDA 21 CFR 177.1520 and EU Regulation 10/2011. The statement applies to the unmodified resin as supplied. A converter adding masterbatch, slip/antiblock concentrate, or post-consumer recyclate changes the compliance status of the finished packaging. Migration testing should be performed on the finished article under EN 1186-1 or equivalent. Published data for specific PTTGC/SABIC LDPE migration results is limited and cannot substitute for article-specific testing.

Masterbatch producers using LDPE as a carrier resin should compare viscosity at shear rates relevant to twin-screw compounding, not only MFR at 2.16 kg. A co-rotating twin-screw extruder with 28–40:1 L/D and temperature profile from 140 °C to 190 °C may show different torque draw between PTTGC and SABIC LDPE grades because of long-chain branching. Capillary rheometry at apparent shear rates from 100 s⁻¹ to 1,000 s⁻¹ under ISO 11443 provides a better ranking than MFR for carrier resin substitution. If the capillary viscosity at 1,000 s⁻¹ deviates more than 10%, a new screw-speed setpoint is required to maintain pigment dispersion and letdown ratio.