REPOL PP Homopolymer H034SG is a reactor-grade propylene homopolymer supplied by Reliance Industries Limited. The grade identifier H034SG belongs to the REPOL PP Homopolymer family and is supplied as unmodified pellets for extrusion, injection moulding, sheet forming, and tape production. Melt mass-flow rate is 3.4 g/10 min at 230 °C under 2.16 kg load when tested in accordance with ISO 1133-1:2022. The nominal density is 0.90 g/cm³ under ISO 1183-1:2019. Because the polymer contains no intentional ethylene comonomer, the crystalline phase is predominantly α-phase isotactic polypropylene; this molecular structure contributes to a high tensile yield stress and flexural modulus while limiting low-temperature impact energy absorption.

The values below are typical datasheet values for the unfilled grade. They are not specification limits and may be revised by the producer when the additive package, pigmentation, or regrind content is changed.

H034SG is positioned between fractional-melt and high-flow homopolymer grades. This supports applications requiring a balance of melt strength and shear flow, such as extruded sheet from 0.5 mm to 2.0 mm, thermoformed food and industrial trays, thin-wall injection-moulded housewares, and slit tape or raffia where draw ratios between 1:5 and 1:8 are common.

What processing limits govern H034SG in sheet and injection moulding?

Melt-phase processing of H034SG is defined by a practical barrel-temperature corridor of 210 °C to 250 °C for single-screw extrusion and 220 °C to 260 °C for injection moulding. At die and nozzle sections, melt temperatures below 210 °C increase back-pressure and may produce unmelts or high melt fracture in thin sections; above 260 °C, oxidative degradation accelerates when the material is held in the melt phase for more than 10 min. On a 60 mm single-screw extruder with a 30:1 L/D barrier screw and a screen pack of 60/80/100 mesh, melt pressure typically stabilises between 80 bar and 180 bar depending on screw speed and die restriction. Production-scale line observations for similar polypropylene homopolymers indicate that pressure fluctuations greater than ±5% across a 10 s interval are usually traceable to poor solids conveying or incorrect barrel-zone balancing rather than melt-flow-rate variation of the resin itself.

In injection moulding, H034SG can be processed with a mould temperature between 20 °C and 50 °C. Lower mould temperatures shorten cycle time but reduce surface replication and may induce post-mould shrinkage; higher mould temperatures improve crystallinity and weld-line strength but extend cooling time. A back pressure of 5 bar to 10 bar and a screw speed of 50 rpm to 120 rpm are typical for this melt-flow class. Clamp force requirements for thin-wall parts with a wall thickness of 1.5 mm to 2.5 mm range from 0.5 tonne/cm² to 0.8 tonne/cm² of projected area, though gating and flow-length-to-thickness ratios above 250:1 require higher holding pressures and may exceed the practical capability of smaller machines.

During continuous extrusion of H034SG sheet with a target thickness of 0.5 mm to 2.0 mm, the melt temperature at the adaptor should be held in the upper half of the processing corridor to reduce die lip build-up; however, for water-quenched slit tape, lower melt temperatures near 220 °C are preferred to maintain melt strength and limit draw resonance. The material’s melt-flow-rate of 3.4 g/10 min provides moderate shear thinning: apparent viscosity at 230 °C and 100 s⁻¹ is expected in the range of 1,500 Pa·s to 2,500 Pa·s for linear polypropylene homopolymers of this MFR, although published data for this specific configuration is limited. Processors using capillary rheometry should collect apparent viscosity data at three shear rates—typically 100 s⁻¹, 500 s⁻¹, and 1,000 s⁻¹—to model the power-law index for die design.

Thermal stability during extrusion is governed by oxygen ingress and residence-time distribution. At melt temperatures above 250 °C, melt-flow-rate drift of more than 15% can occur after 15 min residence in a screw channel with an open feed throat due to β-scission. When processing H034SG with regrind levels above 20 wt%, hopper nitrogen blanketing and a temperature reduction of 5 °C to 10 °C at the feed section are common countermeasures. Pre-drying is not required for sealed packaging; if bags have been open at relative humidity above 70%, drying at 80 °C for 2 h to 4 h in a desiccant dryer with a dew point of -40 °C is recommended to prevent surface splay.

In sheet extrusion, the melt bank between the die exit and the three-roll polishing stack should be kept small to avoid edge encapsulation and air entrapment. Roll temperatures for H034SG are typically set at 70 °C to 90 °C on the top roll, 80 °C to 95 °C on the middle roll, and 60 °C to 80 °C on the bottom roll, depending on sheet thickness and surface gloss. A middle roll temperature below 60 °C can induce surface haze and microcracks in a 1.5 mm sheet; a top roll temperature above 100 °C may cause adhesion and degrade flatness. The sheet should be wound at a surface temperature below 45 °C to prevent blocking and post-winding shrinkage.

For thermoforming, H034SG sheet reaches a forming window between 155 °C and 175 °C surface temperature. Below 150 °C, the material exhibits high elastic recovery and may tear at deep-draw corners; above 180 °C, sag during the oven-index time typically exceeds 25 mm for a 500 mm span and produces non-uniform wall thickness. Zoned ceramic heaters with top-side heat input of 60% to 70% and bottom-side heat input of 30% to 40% are effective for reducing curl on 0.8 mm to 1.2 mm sheet. The exact settings require line-specific profiling because published data for this specific configuration is limited.

When H034SG replaces a random copolymer in rigid packaging

Substitution of a random copolymer with H034SG in rigid packaging increases top-load strength and heat resistance but narrows the optical window. The flexural modulus of 1,700 MPa measured under ISO 178:2019 is typically 40% to 90% higher than that of propylene-ethylene random copolymers used in thin-wall containers. This enables a wall-thickness reduction of approximately 10% to 15% while retaining equivalent sidewall stiffness, provided the thermoforming or injection moulding tooling can compensate for the lower melt elongation at high draw ratios. The heat deflection temperature of 105 °C at 0.45 MPa under ISO 75-2:2013 permits short-duration hot-fill or warm-air exposure at 100 °C to 110 °C, but the polymer should not be used above its Vicat softening temperature of 155 °C under load-bearing conditions without filler reinforcement.

Optical haze is higher for homopolymer than for random copolymer; therefore H034SG is less suitable for critical contact-clarity packaging. For a 1 mm injection-moulded plaque, total luminous transmittance for polypropylene homopolymer is approximately 85% to 90% and haze may exceed 20%, whereas random copolymers can show haze below 10%. The use of nucleating agents or clarified random copolymer grades lies outside the specification of H034SG.

Mould shrinkage for H034SG is approximately 1.2% to 1.8% in the flow direction and 1.0% to 1.6% in the transverse direction when measured on a 60 mm × 60 mm × 2 mm injection-moulded specimen under ISO 294-4:2018. Shrinkage is anisotropic: the ratio of flow-direction to transverse shrinkage is commonly between 1.1 and 1.3. Post-mould crystallisation may increase shrinkage by 0.1% to 0.3% over 24 h at 23 °C, so approval measurements should be taken after full conditioning.

Comparative property profile with random and impact copolymers

H034SG differs from heterophasic impact copolymers primarily in low-temperature impact resistance. The notched Izod impact strength of 3.0 kJ/m² at 23 °C under ISO 180:2019 falls below the impact-copolymer range, which commonly exceeds 6 kJ/m² at -20 °C depending on rubber-phase composition. For applications involving sub-zero impact, H034SG is not the appropriate selection. Conversely, the tensile yield stress of 37 MPa and flexural modulus of 1,700 MPa are higher than those of many impact copolymers, making H034SG more suitable for dimensionally stable components where stiffness is the primary mechanical requirement.

Comparative ranges in the table are representative for unfilled polypropylene grades and depend on comonomer content, rubber-phase morphology, additive package, and test specimen preparation. They are not intended as specification limits for any particular grade.

Compared with high-flow homopolymers in the 10 g/10 min to 12 g/10 min melt-flow range, H034SG retains a longer relaxation time and higher melt strength, which is advantageous in sheet extrusion and profile forming. In thin-wall injection moulding, however, the lower flow of H034SG increases filling pressure and may require a higher melt temperature; for flow-length-to-thickness ratios above 300:1 at wall thickness below 1 mm, a higher-MFR grade may be required.

For food-contact applications, the regulatory status of H034SG should be confirmed with the manufacturer against FDA 21 CFR 177.1520(c)1.1a and European Commission Regulation (EU) No 10/2011. These references apply to propylene homopolymer subject to end-use migration limits. Under REACH Regulation (EC) No 1907/2006, the polypropylene polymer is exempt from registration as a polymer, but the monomer and additive components must be registered or authorised as applicable. RoHS compliance under Directive 2011/65/EU requires a supplier certificate for cadmium below 0.01% and lead below 0.1% in homogeneous materials. The absence of documented lot-level certificates should be treated as a supply-chain risk, not as a material property.

Pellets should be stored below 50 °C and away from direct UV radiation to minimise oxidative degradation of the polymer and additive package. Bags exposed to high humidity should be dried before processing as previously specified. Silo blending of multiple lots is common in sheet extrusion; if melt-flow-rate variation between lots exceeds 0.3 g/10 min, melt-pressure and gauge variation on a 1.2 mm sheet line may become detectable as transverse thickness fluctuations above ±3%.