INVISTA PP Homopolymer P4C5K-123A is a propylene homopolymer supplied in pellet form for injection molding, compounding, and extrusion operations requiring controlled melt viscosity and high stiffness. The grade belongs to the isotactic polypropylene family and develops a crystalline morphology that governs its balance of tensile strength, heat deflection, and resistance to aqueous chemical environments. Published manufacturer data for this specific INVISTA configuration remain limited in public secondary repositories; property values cited below are drawn from ISO and ASTM class data for propylene homopolymers at a nominal melt flow rate of 12 g/10 min and should be confirmed against the current INVISTA product datasheet and lot-specific certificates before production release. The grade is not a rubber-modified impact copolymer and should not be substituted into components requiring ductile failure at sub-zero temperatures without design evaluation.

Which Property Benchmarks Are Reported for P4C5K-123A Against ISO and ASTM Methods?

The following representative values define the stiffness, thermal resistance, and flow behavior of P4C5K-123A as a homopolymer class. The data do not replace a production lot certificate, but they provide the comparative foundation for grade substitution and mold design.

Melt viscosity exhibits pseudoplastic behavior; apparent viscosity decreases with increasing shear rate in capillary rheometry. The viscosity curve is sufficiently shear-sensitive to fill thin sections, but the polymer retains higher stiffness than random copolymers with comparable melt flow rate. The melt flow rate of 12 g/10 min positions the grade between low-flow extrusion homopolymers and high-flow controlled-rheology grades used for multi-cavity thin-wall packaging. Lot-to-lot melt flow variation is typically controlled within ±1.5 g/10 min by the manufacturer, but converters should verify lot-specific values before adjusting hold pressure or gate seal time.

On reciprocating-screw injection machines with screw L/D ratios of 20:1 to 24:1 and compression ratios of 2:1 to 3:1, the recommended melt temperature measured at the nozzle is 220–240°C. The melt should not exceed 260°C during short residence periods; higher temperatures accelerate chain scission and can reduce notched Izod impact by more than 30% after repeated cycles. Mold temperatures between 15°C and 60°C are acceptable, with thin-wall parts typically molded at 40–60°C to reduce premature freeze-off and flow marks. Hydraulic injection pressures of 80–120 MPa are common, with V/P switchover at 95–98% of fill and hold pressures from 30–50 MPa. Back pressure should be limited to 5–10 bar; on 250-ton hydraulic machines, back pressure above 15 bar measurably increases screw recovery time and can generate shear heating, surface splay, and molecular weight loss. Moisture uptake is low, but unsealed storage in ambient relative humidity above 60% for more than 24 h requires drying at 80°C for 2–4 h in a desiccant dryer to hold surface moisture below 0.01%.

When Stiffness-Limited Components Replace Random Copolymer PP at Similar Flow Rates

The selection of P4C5K-123A over a random copolymer polypropylene is governed primarily by flexural modulus and heat deflection requirements. Relative to random copolymers containing 2–4 wt% ethylene, this homopolymer class typically exhibits flexural modulus higher by 25–40% and heat deflection temperature at 0.45 MPa higher by 10–15°C. The trade-off is reduced impact toughness, with notched Izod impact lower by 50–70% at 23°C, and reduced transparency, with haze at 2 mm wall thickness generally higher by 20–30 percentage points. In caps, closures, thin-wall food-service containers, syringe barrels, and chemical-resistant housings, the homopolymer provides sufficient resistance to creep at moderate load and better dimensional stability after washing at elevated temperatures.

Compared with impact copolymer PP containing 8–12 wt% ethylene-propylene rubber, P4C5K-123A delivers tensile stress at yield approximately 20% higher and maintains useful stiffness above 90°C. However, its notched Charpy impact at -20°C is generally below 1.5 kJ/m², whereas impact copolymers can exceed 10 kJ/m² under the same conditions. The grade is therefore unsuitable for frozen-impact applications, automotive interior crash-sensitive brackets, or large blow-molded containers exposed to sub-zero drop tests. The product is intended for stiffness-limited, chemically aggressive, thin-wall injection-molded articles rather than ductile failure modes.

Compounding, Extrusion, and Regrind Stability Boundaries

Twin-screw compounding of P4C5K-123A with mineral fillers or glass fiber can be performed at barrel temperatures from 200°C to 240°C, with screw speeds of 300–600 rpm on co-rotating intermeshing extruders. Addition of talc or calcium carbonate increases flexural modulus and reduces mold shrinkage, but it also lowers tensile elongation at yield and can shift the heat deflection temperature upward by 5–15°C depending on filler loading. Glass fiber at 10–30 wt% raises tensile strength and heat deflection, but abrasive wear on screws, barrels, and check rings increases; nitrided or bimetallic barrels are required for extended production runs. The homopolymer can also be extruded as cast film, strapping tape, monofilament, and sheet at melt temperatures near 220–250°C, with chill roll temperatures below 40°C to reduce haze growth and surface tack.

Regrind stability is acceptable up to 30 wt% regrind in many non-aesthetic injection-molded parts, provided the regrind is dried and free of mixed polymers. Repeated thermal cycles reduce molecular weight and increase melt flow rate; after three closed-loop regrind returns, the effective MFR can rise by 2–5 g/10 min depending on residence time and screw severity. This shift changes fill pressure, shrink, and impact behavior. Use of a low-intensity screw with a minimum residence time and purging after shutdown is required when processing at the high end of the melt temperature window.

P4C5K-123A is not inherently UV-stabilized for prolonged outdoor exposure. Long-term weatherability requires addition of 0.2–0.5 wt% hindered amine light stabilizer and 0.1–0.3 wt% UV absorber masterbatch, with accelerated weathering data generated per ISO 4892-2:2013. The grade is also not designed for prolonged hot-water contact above 80°C under continuous oxidative load, because polypropylene undergoes oxidation and embrittlement over time. Strong oxidizing acids, chlorinated hydrocarbons, aromatic solvents, and long-term contact with vegetable oils at elevated temperatures should be avoided. Aqueous salt solutions, dilute acids, dilute alkalis, and many polar organic media are generally accommodated at room temperature, but chemical resistance must be validated on finished parts under actual stress and temperature conditions, not only on unstressed tensile specimens.

For food-contact applications, compliance may be available under FDA 21 CFR 177.1520 for olefin polymers and under Regulation (EU) No 10/2011, subject to specific migration limits for the antioxidant and processing-aid package. Lot-specific certificates of compliance must be obtained for each production lot, and final article migration testing is required when the packaging is used with fatty, alcoholic, acidic, or high-temperature foods. For electrical and electronic applications, conformity with RoHS Directive 2011/65/EU Annex II and REACH SVHC restrictions should be verified through the current INVISTA safety data sheet and compliance statement. The resin should not be blended with copper-based heat stabilizers or certain amine-based additives that can interact with phenolic antioxidants and produce yellowing or premature loss of thermal protection.