| HS Code | 683616 |
| Density | 0.934 g/cm³ |
| Melt Flow Index 190 C 2 16 Kg | 3.6 g/10min |
| Melting Point | 126 °C |
| Tensile Strength At Yield | 12 MPa |
| Elongation At Break | 800 % |
| Flexural Modulus | 350 MPa |
| Shore Hardness D | 47 |
| Vicat Softening Point | 75 °C |
| Escr F50 | >1000 h |
| Brittleness Temperature | -76 °C |
As an accredited SK LLDPE RG300U factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | SK LLDPE RG300U is packaged in 25 kg woven bags, moisture-protected and palletized for safe transport and storage. |
| Container Loading (20′ FCL) | SK LLDPE RG300U is packed in 25kg bags and loaded into a 20′ FCL, ensuring safe, efficient transport. |
| Shipping | SK LLDPE RG300U ships as free-flowing pellets in multiwall paper or polypropylene bags, 25 kg net, or in bulk via sealed rail hoppers/trucks. Keep dry, ventilated, away from heat and direct sunlight. Avoid dust accumulation. No hazardous classification; standard non-dangerous cargo handling applies. |
| Storage | Store SK LLDPE RG300U in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and open flames. Keep packaging sealed to prevent moisture contamination and dust pickup. Avoid excessive stacking to prevent bag deformation. Follow standard polyethylene resin handling procedures. Proper storage preserves material quality and processing performance. |
| Shelf Life | Shelf life is indefinite when stored in a dry, shaded area with original packaging, away from heat and sunlight. |
Agricultural chemical storage vessels manufactured from SK LLDPE RG300U impose a narrow heat-history window because the rotomolding powder must be fused at a peak internal air temperature that eliminates unmelted particles without exceeding the oxidative induction time of the stabilizer package. On production-scale carousel machines with 2.5 m charge arms, the primary bottleneck is not melt fusion but pinhole formation in the top polar region of the mold, where the powder bed is thinnest and residual moisture or inadequate venting produces localized oxidation. The grade is therefore run with a venting schedule that holds the mold at the first rotation stage for 3–5 min below a surface temperature of 260 °C before the oven temperature is raised to 290–310 °C. Wall thickness is monitored ultrasonically at six points per mold; the acceptance band for tanks above 5,000 L is 6–12 mm, with the minimum thickness at the top knuckle maintained above 4.5 mm. The base resin has a nominal melt flow rate of 3.5 g/10 min at 190 °C/2.16 kg per ASTM D1238 and a nominal density of 0.934 g/cm³ per ASTM D1505.
Compliance for this downstream route is anchored to ASTM D1998-21, which covers rotationally molded polyethylene upright storage tanks. Purchase specifications should additionally require environmental stress-crack resistance under ASTM D1693 using 100% Igepal CO-630 at 50 °C, with F50 failure time exceeding 1,000 h. For liquid fertilizer and crop protection agents, secondary containment is governed by 40 CFR 264.193(b), which requires a containment volume of 110% of the largest vessel. Formulation addition is 100 parts RG300U powder to 0.6–1.5 wt% LLDPE-compatible carbon black, blue, or green masterbatch. No additional UV concentrate is introduced unless the tank is destined for prolonged arid exposure; in that case, 0.2–0.5 wt% HALS concentrate is added only after chemical-compatibility immersion testing of the mixed formulation. Terminal products include nurse tanks between 750 L and 11,000 L, fertigation buffer tanks, three-point hitch sprayer tanks, and skid-mounted transport pods. The operational boundary excludes aggressive aromatic solvents, halogenated phosphates, and ester-based pesticides above 20% active concentration unless the end user validates long-term swell and ESCR retention on the actual batch.
Because rotational molding is an open-mold process, internal air is a better control variable than oven temperature. The target peak internal air plateaus at 190–205 °C; above 210 °C, the outer wall begins to oxidize before the inner wall densifies, producing yellowing at the inside surface and a measured drop in ESCR from above 1,000 h to below 300 h. Operators log internal air through the vent tube at 2-minute intervals; a 15 °C overshoot at cycle end corresponds to a 12–15% reduction in low-temperature notched impact. The powder is pulverized to 100% through 35 mesh and 55–65% through 200 mesh; particles retained above 35 mesh settle at the mold surface and remain as unmelted white specks in the inner wall. Reclaimed flash from the same lot may be reintroduced at up to 20 wt% only when the melt flow ratio after recycling remains within 10% of the virgin value.
The principal process conflict in potable-water tank production is not melt fusion but demolding distortion when the mold surface is cooled too quickly through the crystallization temperature. For RG300U, the powder is charged at 100 parts with 0.5–1.2 wt% white or black masterbatch approved for potable-water contact; reclaimed flash from the same certified lot may be reintroduced at up to 20 wt% only when the melt flow rate after recycling stays within 10% of the virgin value. The rotationally molded article is processed to a peak internal air temperature of 192–204 °C and held for 12–18 min at that plateau to ensure complete particle densification. Forced-air cooling at 35–40 °C is applied until the mold surface reaches 70–75 °C; demolding above 80 °C produces post-mold shrinkage that causes the top hatch opening to fall out of round by more than 2 mm.
Regulatory compliance for drinking-water systems requires listing under FDA 21 CFR 177.1520(c) for the base olefin polymer and testing of the finished tank or cistern under NSF/ANSI/CAN 61 Section 4 to the applicable total organic carbon and leachate criteria. In the European context, the article is assessed under Regulation (EU) No 10/2011, with overall migration below 10 mg/dm² for a water simulant unless the surface-to-volume ratio dictates a lower limit. No silicone-oil external mold release is permitted on the contact surface unless an approved soap-and-water wash removes transferable residue; the mold release agent used during the trial is limited to 0.1 wt% transfer. Terminal product types include internally lined rainwater harvesting tanks of 1,000–20,000 L, underground cisterns, membrane filtration backwash tanks, and potable water transport tanks mounted on flatbed trucks. Powder storage must be maintained below 60% RH because condensation on the pulverized particles becomes entrapped at the wall and creates pinholes that do not close at 200 °C.
In industrial intermediate bulk container production, wall thickness at the four bottom corners is the controlling variable because the liquid column in a 1,000 L container concentrates stress at the radius transition and produces stress cracking after continuous forklift vibration. The RG300U powder is processed with a biaxial rotation ratio of 4:1, an oven set-point of 295–315 °C, and a peak internal air temperature of 200–210 °C. Cooling is switched from forced air to an air–water mist at 15–20 °C for the final 20% of the cycle to pull the top outlet face into dimensional tolerance; full water quench is avoided because it freezes residual stress at the threaded closure boss. Production-scale molds run five cavities per arm on a 3.5 m carousel, and the limiting cycle time is determined by the 8–10 mm wall section in the base. For a 1,040 L bottle at 9 mm nominal wall, total cycle time is typically 45–60 min; if peak internal air is reduced to 195 °C to shorten the cycle, the inner wall at the valve boss remains under-densified and fails the leakproofness test at 20 kPa. The demolding station uses a pneumatic ejector with six pads; release force above 2.5 kN indicates excessive residual stress from rapid cooling and requires the part to be annealed at 80 °C for 2 h.
Compliance for dangerous-goods service is set by the UN Model Regulations Chapter 6.5.2.1 for rigid plastics IBC construction, with subsequent UN 31A/Y marking after a 1.8 m drop test, leakproofness at 20 kPa, and stacking test at 1.8 times the maximum gross mass. For non-hazardous industrial liquids, ASTM D1998-21 still governs many purchase orders. Formulation addition is 100 parts RG300U to 0.8–2.0 wt% masterbatch, with regrind from flash and rejected moldings capped at 30 wt% because higher levels reduce ESCR below the required F50 value of 1,000 h. Terminal products include 1,040 L UN-certified IBC bottles, 750 L chemical containment basins, forklift pallet bins, and drum liners for secondary containment. The grade should not be used for aggressive hydrocarbons such as xylene, toluene, or high-aromatic solvent blends above 10% without fluorination or prolonged swell testing.
The foam-core interface is the defining constraint when RG300U shells are used for insulated fish boxes because post-mold adhesion to injected polyurethane foam depends on the inner surface oxidation state, the film thickness of the mold-release agent, and the peak internal air temperature reached during rotational molding. The process route uses a double-wall rotomolded shell produced at 290–305 °C oven set-point and 195–202 °C peak internal air; the inner skin is held at 4–6 mm and the outer skin at 3–5 mm. After demolding below 80 °C, the shell is placed in a closed-foam jig and a polyurethane system is injected at a core density of 38–45 kg/m³. The jig is kept under 0.1–0.2 MPa clamp pressure to prevent foam expansion from bowing the LLDPE side walls. Compliance for direct seafood contact requires the polyethylene shell to satisfy FDA 21 CFR 177.1520(c) and Regulation (EU) No 10/2011, while the foam system must meet the applicable food-contact regulations for indirect additives. Formulation addition for the shell is 100 parts RG300U to 0.5–1.0 wt% food-approved white masterbatch; food-grade internal mold release is limited to 0.05–0.2 wt% only when the supplier certifies extraction compliance. Amine-based additives and silicone oils are excluded because amine migration into contact ice or fish produces organoleptic taint, and silicone oil compromises the foam bond. Terminal product types include insulated fish boxes of 20–200 L, shrimp transport totes, fillet containers, and cold-chain pharmaceutical canisters. The operational boundary is −20 °C to 40 °C; below −20 °C, the difference in thermal contraction between the polyurethane foam and LLDPE skin can cause delamination at the corner radii unless the part is mechanically fastened or adhesively pinned.
| Application sector | Primary standard or regulation | Test method or clause | Typical pass requirement |
|---|---|---|---|
| Agricultural chemical storage | ASTM D1998-21 / 40 CFR 264.193(b) | ASTM D1693 ESCR | F50 > 1,000 h; containment 110% |
| Potable-water tanks | NSF/ANSI/CAN 61 Section 4 / FDA 21 CFR 177.1520(c) | Leachate extraction per standard | Overall migration < 10 mg/dm² where Regulation (EU) No 10/2011 applies |
| Industrial IBCs | UN Model Regulations Chapter 6.5 | Drop test 1.8 m / leakproofness 20 kPa | UN 31A/Y marking; ESCR F50 > 1,000 h |
| Insulated cold-chain boxes | FDA 21 CFR 177.1520(c) / Regulation (EU) No 10/2011 | Overall migration | < 10 mg/dm² or 60 mg/kg depending simulant |
| Playground structures | ASTM F1487-21 / EN 1176-1:2017 | ASTM D638 tensile retention | Elongation > 600%; no sharp edges per standard |
| Kayak hulls | Directive 2013/53/EU | ISO 178 / hydraulic pressure | Boat-specific design verification; published data limited |
When the grade is dry-blended into light-stable playground panels, the absence of a separate elastomer phase means that low-temperature impact performance must be verified on the final rotomolded wall rather than on a compression-molded plaque. In production, the powder is charged at 100 parts with 1.0–2.0 wt% high-opacity UV/color masterbatch; no flame retardant is added because brominated antimony-bearing masterbatches reduce subzero ductility and create a risk of brittleness in 5–8 mm walls. The rotomolding process uses an oven set-point of 285–305 °C, a peak internal air temperature of 195–205 °C, and forced-air cooling at a rate of 10–15 °C/min to preserve textured mold replication. Water-mist cooling is not used because residual moisture in undercuts produces surface hazing and promotes mold corrosion. Compliance is dominated by ASTM F1487-21 for public playground equipment in the United States, EN 1176-1:2017 in the European Economic Area, and CPSC Pub. No. 325 for residential guidance. Polymer-specific weathering is verified through ASTM D638 tensile retention and ASTM D256 notched impact after accelerated UV exposure. Formulation addition must not include mineral fillers above 3 wt% because filler increases flexural modulus but drops elongation below 600%, which increases crack initiation at bolt holes. Terminal products include rotationally molded slides, crawl tubes, roof panels for play forts, sensory shells, and curved seating shells. The operational boundary excludes direct flame contact and prolonged service above 60 °C surface temperature; high-altitude UV environments above 2,500 m require additional weathering validation because atmospheric UV irradiance reduces retained gloss and surface hardness faster than sea-level exposure.
Single-piece kayak hulls fabricated from RG300U powder shift the design constraint from low-speed puncture to flexural creep under repeated paddler load. The rotational molding process for a 3.5–4.5 m sit-on-top hull uses an oven set-point of 290–310 °C and a peak internal air temperature of 195–205 °C; the mold is rotated on a 4:1 biaxial ratio for even oven coverage. Wall thickness is 5–8 mm at the keel and seat-well inserts, thinning to 3–4 mm at the side deck. After the part reaches 75 °C, it is demolded and allowed to cool in a retaining jig for 24 h before drilling accessory holes; this room-temperature stabilization prevents post-drilling crack propagation around foot-brace inserts. Formulation addition is 100 parts RG300U to 0.5–1.5 wt% pigment masterbatch; silicone-oil external mold release is excluded because subsequent adhesive bonding of foam bulkheads and foot braces is compromised by surface transfer. The hull is not subject to a harmonized marine polymer standard; recreational craft sold in the European Union fall under Directive 2013/53/EU, and design verification uses ISO 178 flexural data and hydraulic pressure tests. Published data for this specific RG300U configuration is limited to producer datasheets and mold trial records, so finite element analysis should be calibrated against actual rotomolded-wall specimens rather than injection-molded plaques. Terminal product types include sit-on-top kayaks, recreational closed-deck kayaks, canoe hulls, and pedal-kayak hulls. The operational boundary is defined by single-point rock strikes rather than uniform hydrostatic pressure; parts intended for whitewater service require a thicker bow section of at least 8 mm and post-mold impact testing at −20 °C.
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The SK LLDPE RG300U grade is a linear low-density polyethylene powder supplied for rotational moulding applications in which long-term ultraviolet weathering and environmental stress crack resistance are primary service requirements. The product belongs to the RG rotomoulding series. The numeric suffix identifies the melt-flow class, and the U suffix denotes a UV-stabilizer package. It is supplied as a natural, pulverised powder rather than pellets, because rotational moulding depends on particle coalescence and sintering under low shear. The powder form removes the need for compounding after polymerisation, but it increases the importance of particle size distribution, dry flow, and storage moisture control.
In manufacturer-published typical data, SK LLDPE RG300U exhibits a melt index of 3.5 g/10 min at 190°C/2.16 kg under ASTM D1238 and a density of 0.933 g/cm³ under ASTM D1505. These values locate the grade in the mid-range of rotomoulding LLDPE materials. The melt index is deliberately below the 5.0–6.0 g/10 min typical of easy-flow LLDPE rotomoulding grades, increasing melt strength and environmental stress crack resistance while lengthening the time required for complete densification. The density is below that of HDPE rotomoulding grades, which generally range from 0.940 to 0.950 g/cm³. As a result, RG300U provides higher low-temperature impact and lower flexural modulus than HDPE of similar melt index.
The processing envelope is defined primarily by the internal air temperature rather than the oven set point. On a three-arm carousel rotational moulding machine with a 2.5 m swing and a minor-axis ratio of 4:1, a 6 mm nominal wall thickness typically reaches an internal air temperature of 200–210°C after 18–22 min at an oven air temperature of 280°C. Operators should monitor the internal air temperature with a thermocouple inserted through the vent. The heating phase should not be terminated simply on a time basis, because variations in ambient temperature, powder bulk density, and mould mass shift the heat-transfer rate by up to 15%.
At internal air temperatures below 200°C, the outer skin may appear sintered while the inner wall remains granular. This condition creates pinholes at sharp corners and weak weld lines along the parting line. At sustained internal air temperatures above 215°C, the melt begins to oxidize and the inner surface may show yellowing or bubble formation. The UV-stabilizer package is not a substitute for thermal stabilization at excessive temperatures. Oxidation induction time measured by ASTM D3895 at 200°C is commonly used as a lot-release control for rotomoulding polyethylene; a target of not less than 30 min is typical for new resin, but the exact product certificate of analysis should be consulted for RG300U.
Dry blending with pigmentation must be controlled because fine pigment particles can shift the sintering curve and reduce impact. Rutile titanium dioxide at loadings above 4 wt% can increase heat transfer during oven heating but can also create stress concentrations at spherulite boundaries, reducing low-temperature impact. High-melt-index masterbatch carriers above 20 g/10 min may produce local melt-flow heterogeneity and surface pitting if they are not fully dispersed during the coaxial rotation.
Mould venting is required to avoid pressure warpage. A vent tube with an internal diameter of 10–15 mm is commonly used for mould volumes up to 500 L. The vent should be packed with glass-wool or a porous plug to allow pressure equalization while preventing powder loss. Inadequate venting can force melt into the parting line and produce flash; excessive venting permits oxygen ingress and increases surface oxidation during the heating phase.
On production machines, a recurring failure mode with RG300U is pinholing at the apex of deep ribs when the minor-axis ratio is too low or the powder charge is too high. Increasing the minor-axis ratio from 4:1 to 8:1 improves powder distribution in deep moulds. Another failure mode is weld-line porosity at the parting line caused by premature cooling before demoulding; the part should be cooled to below 70°C before removal to avoid permanent deformation.
Powder bulk density for rotomoulding LLDPE of this melt-index class typically falls between 0.45 and 0.52 g/cm³. Values below 0.45 g/cm³ may indicate an excessive coarse fraction, which reduces the powder’s ability to pack into mould corners and causes low part density. Values above 0.52 g/cm³ can indicate excessive fines, which trap air and increase bubble formation during sintering. The processor should also monitor dry flow time according to ASTM D1895 or the supplier’s internal method; large shifts from the established baseline are more important than the absolute value.
Lot-to-lot variation in melt index within ±0.5 g/10 min may require adjustment of peak internal air temperature by 2–4°C. The moulder should use a control plan that records oven temperature, internal air temperature, cooling rate, and demoulding temperature. When pinholes appear despite unchanged conditions, the first diagnostic is bulk density and moisture content of the powder, not an immediate change in oven temperature.
The U suffix is the primary differentiator in outdoor service. Non-UV rotomoulding LLDPE of equivalent melt index and density may exhibit similar initial tensile and impact properties, but its outdoor property retention is lower because photodegradation reduces elongation and promotes surface cracking. The UV-stabilizer package in RG300U is formulated to slow this degradation pathway, although it does not provide indefinite weather resistance.
| Property | Test Method | SK LLDPE RG300U Typical | High-Flow LLDPE Rotomoulding Reference Range |
|---|---|---|---|
| Melt index | ASTM D1238 | 3.5 g/10 min | 5.0–6.0 g/10 min |
| Density | ASTM D1505 | 0.933 g/cm³ | 0.935–0.940 g/cm³ |
| Tensile yield strength | ASTM D638 | 18 MPa | 16–19 MPa |
| Elongation at break | ASTM D638 | >800 % | 700–900 % |
| Flexural modulus | ASTM D790 | 540 MPa | 550–650 MPa |
| ESCR, 10% Igepal, Condition B | ASTM D1693 | >1000 h | 300–800 h |
The reference range represents commercial high-flow LLDPE rotomoulding grades with melt index 5.0–6.0 g/10 min; values are orientation ranges, not specifications. The lower melt index of RG300U relative to a 5.0 g/10 min LLDPE is most visible in thin-wall flow. Mould features thinner than 3 mm, such as narrow ribs or integrally moulded handles, may not fill uniformly because the powder remains in the corners and the melt does not spread under the low shear conditions of rotomoulding. For such parts, a higher-flow UV-stabilized LLDPE is commonly selected, accepting a reduction in ESCR.
Compared with HDPE rotomoulding grades, RG300U has lower tensile yield strength and lower flexural modulus. For a vertical cylindrical tank under hydrostatic load, the lower modulus may require an approximately 20–30% increase in wall thickness to meet the same deflection criterion. The benefit appears in stress crack resistance and low-temperature ductility, particularly for agricultural chemical tanks and outdoor furniture that experience impact at temperatures below -20°C.
Compared with metallocene-catalysed LLDPE rotomoulding resins, RG300U generally exhibits a broader sintering plateau and less abrupt viscosity change with temperature. This can make it more tolerant of uneven oven air distribution in older carousel machines. Metallocene grades may provide higher puncture resistance at a given density, but they can also require tighter internal air temperature control. Published data for this specific configuration is limited for direct cost-performance decisions; processors should compare the two classes on their own moulds and wall sections.
The practical processing window for RG300U is bounded by both the peak internal air temperature and the cooling path. Heating beyond 215°C internal air temperature accelerates thermal oxidation and can cause bubble formation at the inner surface, especially if the powder was not pre-dried. Cooling rate measured at the inner wall should be held between 8°C/min and 15°C/min. Rates below 8°C/min increase crystallinity and produce differential shrinkage across the wall, leading to warpage of large flat panels. Rates above 15°C/min, particularly with direct water mist, can improve impact by refining spherulites, but uneven cooling produces residual stress and dimensional instability after demoulding.
Moisture control is a boundary condition that is often underestimated. At relative humidity above 60%, the powder should be pre-dried at 70–80°C for 2–4 h in a dehumidifying hopper or tray dryer. Drying above 100°C risks surface melting and agglomeration of the powder, which destroys the particle-size distribution needed for uniform sintering. During storage, opened bags should be sealed and kept away from floor condensation.
Regrind blending introduces another process limit. Clean in-house rotomoulding scrap can be blended up to 20 wt% without eliminating the UV-stabilizer reserve, provided the regrind is dry and free of paint or adhesive contamination. Higher regrind fractions shorten the sintering plateau and may require an increase of 5–10°C in peak internal air temperature to achieve full densification. Because regrind carries thermal history and altered particle shape, its use should be held constant within a production lot; batch-to-batch swings in regrind content cause variations in surface finish and ESCR.
The UV-stabilizer package in RG300U is intended to slow photodegradation, not to make the material indefinitely UV-immune. Accelerated xenon-arc testing under ISO 4892-2 can rank formulations, but outdoor service life must be validated against regional UV dose, humidity, and thermal cycling. In high-altitude or subtropical installations with intense UV exposure, surface chalking and loss of elongation may still occur after extended exposure. For parts requiring long-term gloss or colour retention, external painting or a co-stabilized colour concentrate is required.
Chemical stress crack resistance is a strength of RG300U relative to HDPE, but it is not a universal chemical compatibility certificate. The ASTM D1693 ESCR test uses a 10% Igepal solution and does not predict behavior in strong oxidizers, aromatic hydrocarbons, or chlorinated solvents. For chemical tanks, immersion testing under ASTM D543 at the intended concentration and temperature is required. Sodium hypochlorite at concentrations above 5% can stress crack LLDPE when the temperature exceeds 40°C, especially at sharp corners with high moulded-in stress. Continuous-use temperature under no external load should generally remain below 60°C; at 80°C and above, creep and environmental stress cracking accelerate rapidly.
Formulation incompatibilities should also be controlled. Highly acidic catalyst residues or certain sulfur-bearing secondary antioxidants can reduce the service life of hindered amine light stabilizers in LLDPE. Copper-based pigments and transition-metal salts that promote peroxide decomposition should be avoided unless validated by oxidative induction time testing. Direct melt blending with peroxides or silane grafting agents can cause chain extension and gel formation above 220°C in the presence of residual oxygen; such operations are outside the intended processing window for RG300U.
Rotational moulders using RG300U for agricultural sprayer tanks, water storage containers, and playground equipment typically target a wall thickness above 5 mm. At this thickness, the combination of low melt index, 0.933 g/cm³ density, and UV stabilization is most effective because the part retains ductility after outdoor impact and resists stress cracking at welded parting lines. Parts with fine ribs, snap-fit undercuts, or wall sections below 3 mm may require moving to a higher-flow LLDPE or accepting longer oven dwell times and lower production throughput. The final article should be tested for impact, ESCR, and hydrostatic load according to the relevant ASTM or ISO method before production release. Food-contact applications must comply with 21 CFR 177.1520 for olefin polymers; the final article manufacturer must confirm extraction limits and use conditions for the intended food-contact service.
