Designated as a heterophasic polypropylene impact copolymer, MOPLEN PP EP340M is supplied for injection-moulded articles requiring a controlled balance between flexural stiffness and low-temperature impact energy absorption. The grade consists of a continuous isotactic polypropylene matrix and a dispersed ethylene-propylene rubber phase. This two-phase morphology provides an energy-dissipation mechanism under rapid strain; visible light scattering from the dispersed rubber domains reduces total luminous transmittance to below 70 % when measured to ASTM D1003 on 2 mm plaques. The nominal melt flow rate, determined in accordance with ISO 1133-1:2022 at 230 °C under 2.16 kg, is 4.0 g/10 min. Density measured to ISO 1183-1 at 23 °C is 0.900 g/cm³. These two values place the product in a low-flow, medium-stiffness segment of the producer's injection-moulding portfolio, suitable for articles where high-flow grades fail during chilled-drop impact or sub-zero service.

For feedstock handling, pellet moisture content is maintained below 0.05 wt%. Although polypropylene is not hygroscopic, condensation on cold pellet surfaces stored at relative humidity above 60 % must be removed before processing. A desiccant dryer operating at 80 °C for 2 h to 4 h with a dew point of -30 °C or lower prevents silver streaks and splay in polished cavity surfaces. Failure to pre-dry in humid environments has been observed on production lines as surface splay concentrated at the gate area, with batch-to-batch variance exceeding ±10 % in surface-gloss retention measured to ASTM D523 at 60° specular incidence.

Rheologically, EP340M shows a broad molecular weight distribution with shear-thinning behaviour typical of heterophasic polypropylene. Capillary rheometry to ISO 11443 at 230 °C indicates that viscosity decreases from approximately 900 Pa·s at 100 s⁻¹ to below 280 Pa·s at 1000 s⁻¹; these values are characteristic of impact copolymers in the 4 g/10 min melt-flow range and support filling of medium-thickness sections. The low melt flow rate restricts spiral flow length in sections below 1 mm, especially when combined with chilled mould walls below 40 °C. At 2 mm wall thickness and 800 bar specific injection pressure, spiral-flow length to ASTM D3123 is typically 450–550 mm. Higher-flow heterophasic grades with MFR above 15 g/10 min achieve 650–800 mm under the same conditions, but fracture energy at -20 °C declines sharply due to lower molecular weight.

What Happens When Melt Temperature Drops Below 220 °C in Thin-Wall Tooling?

Production-scale injection-moulding validation on a 350 t hydraulic clamp machine with a 32 mm diameter screw of L/D 22:1 and compression ratio 2.2:1 identified a lower practical melt-temperature limit of 220 °C for sections thinner than 1.5 mm. At 200 °C to 210 °C, flow-front hesitation and incomplete replication of texture occurred in a 1.2 mm rib pattern; weld-line tensile elongation measured to ISO 527-2 was reduced by more than 20 % relative to the same tool run at 240 °C. The dispersed ethylene-propylene rubber phase remains too viscous to orient uniformly at the flow front at low temperatures, producing streak-like inclusions visible in transmitted light. The recommended melt-temperature window is therefore 200 °C to 250 °C, with the lower boundary acceptable only for thick parts above 3 mm and the upper boundary limited by colour shift in nucleated masterbatch systems. Screw rotation speed should be 80–140 rpm for screws of 32–40 mm, and hydraulic backpressure should be held at 4–10 MPa to prevent unmelted pellet bypass. Mould temperatures are set between 20 °C and 60 °C; temperatures below 20 °C generate frozen-in stress in thick bosses, while temperatures above 60 °C increase crystallisation shrinkage and can push total mould shrinkage to the upper end of the 1.0–1.4 % range measured to ISO 294-4.

Injection-speed profiling is used to manage shear heating in the melt stream. When filling thick bosses adjacent to thin ribs, a two-stage velocity profile of 60–80 mm/s for the thick section and 120–180 mm/s for the thin ribs avoids hesitation lines. This was demonstrated on a 280 t all-electric machine with a 30 mm screw, where a constant injection velocity of 100 mm/s produced visible hesitation marks at the transition from 4 mm to 1.2 mm wall thickness. Switching to profiled velocities and maintaining melt temperature at 235 °C eliminated the defect and improved weld-line elongation by 18 %.

Transport packaging, automotive interior structural carriers, and appliance housing components are the primary application segments for EP340M. Battery housing components benefit from the combination of puncture toughness and resistance to dilute alkaline exposure; puncture impact at -20 °C measured to ISO 6603-2 on 2 mm injection-moulded plaques typically exceeds 4 J, although published data for this specific battery-housing configuration is limited. Notched Charpy impact at 23 °C, tested to ISO 179-1/1eA, is typically in the range 12–20 kJ/m²; at -20 °C the range falls to 4–7 kJ/m². These values make the material suitable for crates, tote bins, and structural pails that are dropped from loading-dock height at low ambient temperature. Transparent thin-wall food containers are not a recommended application because the rubber phase scatters light and reduces clarity; random copolymer grades are used when contact clarity and hot-fill haze are specified.

Contrasting EP340M with High-Flow Heterophasic and Random Copolymer Grades

Within the Moplen injection-moulding portfolio, EP340M occupies a low-flow, high-toughness position. High-flow heterophasic grades with melt flow rates above 15 g/10 min reduce cycle time and permit thinner nominal wall sections, but their notched impact performance at -20 °C is generally 30–50 % lower than that of a 4.0 g/10 min grade. Random copolymer polypropylene grades offer transparency above 80 % light transmission and lower sealing initiation temperature, but they exhibit lower stiffness, lower heat-deflection temperature, and lower sub-zero impact strength. EP340M is therefore selected when opacity is acceptable and field failure mode is ductile-brittle transition in chilled service. Compared with isotactic homopolymer grades of similar melt flow rate, EP340M has lower elastic modulus and lower surface hardness because the rubber phase disrupts crystallinity. Pencil hardness measured to ASTM D3363 is typically HB–2B, whereas homopolymer grades are usually F–H. For structural clips where creep resistance and dimensional retention at 80 °C are more important than impact, a homopolymer grade may be preferable. EP340M is not recommended for continuous service above 90 °C in load-bearing parts because modulus retention under load drops below 50 % at 100 °C relative to 23 °C. The table below summarises the representative test matrix for this grade.

The representative ranges are compiled from producer technical literature and compounder quality-control records. Lot-specific values should be verified against the current certificate of analysis because rubber-phase concentration and molecular weight can shift within the stated range during campaign-to-campaign transitions at the polymerisation unit.

Dynamic mechanical analysis of pressed plaques to ISO 6721-7 typically places the polypropylene matrix glass transition near 0–5 °C, while the dispersed rubber phase shows a loss-modulus peak between -45 °C and -30 °C. This secondary transition is responsible for the retention of impact energy below freezing. The exact position of the rubber-phase peak depends on ethylene content and sequence distribution, which explains why low-temperature Charpy results can vary by ±2 kJ/m² across production campaigns. Users performing incoming quality control should measure notched Charpy at -20 °C rather than relying solely on melt flow rate, because MFR does not adequately capture rubber-phase cross-distribution changes.

Mould shrinkage anisotropy is also a critical boundary condition. On centre-gated plaques, shrinkage in the flow direction is typically 0.4–0.6 % lower than in the transverse direction; this differential contributes to warpage in flat lids and must be compensated by tool design rather than extended packing. Packing pressure should be 60–80 % of injection pressure, and hold time should be set to gate-sealing time plus 0.2 s. Overpacking beyond this threshold increases sink-mark depth in ribbed sections and raises demoulding ejection force by approximately 10–15 %.

If Regulatory Compliance Is Required for Food-Contact or Automotive Articles

Verification of food-contact suitability for MOPLEN EP340M must be obtained through the producer's regulatory affairs statement. Polypropylene impact copolymers are generally covered by FDA 21 CFR 177.1520 for olefin polymers and by EU Regulation (EC) No 1935/2004 when the grade is listed in the producer's food-contact statement; however, the dispersed ethylene-propylene rubber phase and any nucleating or antistatic additives can modify overall migration and specific migration limits under EU Regulation (EC) No 10/2011. Electrical and electronic applications require RoHS recast 2011/65/EU compliance for lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ethers, with supplier certificates typically stating values below the maximum concentration value of 1000 ppm for restricted substances except cadmium at 100 ppm. REACH registration under EC 1907/2006 is maintained for polymer substances, but imported formulations containing additives must be assessed for substances of very high concern above 0.1 wt%.

Automotive interior applications may also require compliance with ISO 3795 or FMVSS 302 for horizontal burn rate. Producers typically list a burn rate of 25–100 mm/min for unfilled polypropylene, but the rubber phase and any flame-retardant masterbatch can shift this value; end-use testing on the exact wall thickness is required.

In a multi-cavity crate tool running on a 450 t toggle clamp machine, batch-to-batch variation in pelletised ethylene content caused weld-line Charpy impact to shift by ±15 % when regrind levels exceeded 20 wt%. Maintaining regrind below 15 wt% and controlling hot-runner manifold temperature at 230–240 °C reduced this variation to ±6 %. The material should not be purged with polyamide or polyethylene terephthalate residues because immiscible melt pockets will appear as delamination at gate-freeze boundaries after painting or adhesive bonding. For colouring, a polypropylene-based masterbatch at 2–4 wt% is recommended; carrier resins with melt flow rates below 1 g/10 min should be avoided because they can produce visible dispersion defects in thin ribs and weld lines. If antistatic or nucleating additives are required, compatibility trials should be performed at the minimum addition level 0.1 wt% because some nucleating agents shift crystallisation onset to higher temperature and reduce mould filling pressure loss by 10–20 %.