Designated PP-H under ISO 1043-1, TIPPLEN (MOL Petrochemicals) PP Homopolymer is an isotactic propylene homopolymer produced without ethylene comonomer. The grade slate includes H 145 F, H 385 F, H 649 D, H 880 F, and H 890 F, spanning nominal melt mass-flow rate classes from 2.6 g/10 min to 18 g/10 min at 230 °C under 2.16 kg load according to ISO 1133-1. Density is typically 0.90 g/cm³ as determined by ISO 1183-1. The absence of ethylene comonomer produces higher crystallinity, higher flexural modulus, and lower low-temperature impact strength than TIPPLEN random or impact copolymer grades. The xylene-soluble fraction, measured according to ISO 16152, is generally below 5 wt%, indicating high isotacticity. The material is supplied as pellets for film extrusion, fibre/raffia conversion, and injection moulding. Compared with random copolymers, the homopolymer offers higher stiffness and upper service temperature but reduced optical clarity in thick sections and reduced sub-zero impact toughness; compared with impact copolymers, it contains no dispersed ethylene-propylene rubber phase and therefore gives higher rigidity but lower crack propagation resistance under impact loading.

Typical homopolymer flexural modulus values range from 1450 MPa to 1600 MPa under ISO 178, while many random copolymers fall below 1000 MPa. Vicat softening temperature is generally above 150 °C when tested by ISO 306/A50, whereas random copolymers are commonly below 130 °C. Notched Charpy impact at −20 °C is usually below 2 kJ/m² according to ISO 179-1/1eA, while impact copolymers may exceed 6 kJ/m² to 10 kJ/m². These property differences define the application boundary: the homopolymer is suitable for rigid parts, oriented film, textile fibre, and technical injection mouldings requiring dimensional stability, but it is not appropriate for freezer impact containers or transparent flexible packaging where random copolymer or impact copolymer grades are required.

What Melt Flow Rate Boundaries Separate Film, Fibre, and Injection Moulding Grades?

Melt mass-flow rate (MFR) is the primary specification for assigning TIPPLEN PP homopolymer grades to conversion processes. Grades with MFR near 2.6 g/10 min are intended for biaxially oriented film because high melt strength resists sagging and stabilises the melt bank. Grades at 8.0 g/10 min to 12 g/10 min are used for cast film, tape, and fibre because they balance extruder back pressure against line speed. Grades at 16 g/10 min to 18 g/10 min are intended for high-speed injection moulding and thin-wall packaging, where lower melt viscosity reduces injection pressure and shortens cycle time. The following table lists representative typical values from MOL technical bulletins. These values are not specification limits and must be verified against the grade-specific certificate of analysis.

The flexural modulus values above are obtained at 23 °C using a 2 mm/min test speed. The notched Charpy values are obtained using type 1eA specimens. The differences in MFR between H 145 F and H 890 F correspond to more than a fivefold reduction in melt viscosity, which changes not only throughput but also shear heating behaviour in the extruder. Higher-MFR grades generate less viscous heat but require more careful screw speed control to avoid barrel temperature override.

Injection Moulding Processing Boundaries and Tool Temperature Control

Injection moulding grades such as H 649 D are processed at melt temperatures of 220 °C to 260 °C and mould temperatures of 20 °C to 50 °C. On a reciprocating screw machine with clamp force from 800 kN to 1500 kN, screw L/D 20:1, and a non-return valve, low mould temperatures reduce cycle time but increase frozen-in orientation and residual stress. At mould temperatures below 10 °C, weld lines in unfilled homopolymer can show visible surface discontinuity and reduced tensile strength when tested according to ISO 527-2. Injection speed should be high enough to fill before the flow front freezes, typically 100 mm/s to 300 mm/s; however, excessive speed produces jetting and splay. Hold pressure of 40 MPa to 80 MPa compensates for volumetric shrinkage. Screw plastication rates are typically derated by 10% to 15% when adding 2 wt% to 4 wt% colour masterbatch because viscosity stratification can cause melt temperature heterogeneity at the nozzle.

Mould shrinkage of unfilled homopolymer measured according to ISO 294-4 is typically 1.0% to 1.8%; post-mould crystallisation can increase total shrinkage over 24 h. Shrinkage anisotropy is influenced by gate geometry and flow direction. For dimensionally stable parts, the mould should be designed with gate positions that avoid opposing flow fronts meeting in visible areas. Hot runner temperatures should remain below 280 °C; residence time above 10 min at 280 °C initiates oxidative degradation, causing discolouration and reduced elongation at break under ISO 527-2. The upper melt temperature boundary is therefore a process safety limit, not a recommended operating point.

Cast film and biaxially oriented film conversion use the lower-MFR TIPPLEN homopolymer grades. On a 90 mm single-screw extruder with L/D 30:1 and barrier screw, melt temperature for cast film is set between 240 °C and 260 °C; the chill roll is maintained at 20 °C to 30 °C to maximise gloss and limit crystallisation rate. Melt temperature above 280 °C initiates oxidative degradation of the polymer chain, causing gel formation and reduced elongation at break when tested by ISO 527-3. Biaxially oriented film lines require polypropylene with MFR below approximately 3.5 g/10 min to maintain melt bank stability at the die lip; if MFR is too high, the web thins unpredictably and draw resonance occurs in machine direction orientation. For H 145 F, typical machine-direction draw ratio is 4:1 to 5:1 at 145 °C to 155 °C, and transverse direction draw ratio is 8:1 to 10:1 at 155 °C to 165 °C. Chill roll temperature above 30 °C can suppress the formation of a fine smectic structure and increase haze, which is quantified by ASTM D1003 or ISO 13468-1. The homopolymer’s high crystallisation rate therefore makes the cast film chill roll boundary a critical threshold; a temperature deviation of ±5 °C can shift gloss and haze outside acceptable optical limits.

When Fibre Spinning Demands Narrow Molecular Weight Distribution

High-speed fibre and raffia tape production requires controlled-rheology homopolymer with narrow molecular weight distribution. Grades H 880 F and H 890 F are processed at melt temperatures from 220 °C to 270 °C using spinneret holes from 0.25 mm to 0.80 mm; narrow distribution reduces die swell and filament diameter variance. Water-quench multifilament lines typically operate with quench water temperature 20 °C to 40 °C, and drawing is performed at draw ratios 3:1 to 7:1 at temperatures below the melting point. The resulting tapes show high tensile tenacity but lower elongation at break than random copolymer grades because the homopolymer crystal lamellae orient more efficiently; tensile properties are measured according to ISO 527-3 or ISO 2062 for filaments. A narrow molecular weight distribution also reduces the tendency for fibre fusing at high line speeds. However, the processing window for melt temperature remains ±5 °C around the set point in water-quench systems because overheating causes filament breaks and undrawn material in the spin pack. Extruder zone control calibration is therefore critical for stable multi-end spinning.

Compliance Matrix for Food Contact, Automotive, and Electrical Applications

Food-contact use requires grade-specific verification. TIPPLEN PP homopolymer grades are generally certified for compliance with EU Regulation (EC) No 1935/2004 and EU No 10/2011 when used under the specified migration limits; the overall migration limit is 10 mg/dm² for food simulants. US food-contact status is assessed under FDA 21 CFR 177.1520 for olefin polymers. Automotive and electrical applications require RoHS compliance under Directive 2011/65/EU and REACH SVHC screening; specific additive packages may require the buyer to confirm absence of substances above 0.1 wt% in homogeneous material. The following matrix lists the principal standards applicable to the homopolymer as supplied. The values are not performance guarantees and must be verified against the lot-specific certificate of analysis.

Storage of the homopolymer at relative humidity above 60% or exposure to ambient moisture can raise surface moisture above 0.1 wt%, which may cause splay or surface defects during extrusion. In such cases, a desiccant dryer with dew point of −30 °C or lower should be used at 80 °C for 2 h to 3 h. The unmodified homopolymer is not recommended for continuous use above 90 °C in air without heat stabilisation because oxidative chain scission reduces molecular weight and embrittles the part; this is particularly relevant in under-bonnet automotive components where peak temperatures exceed 110 °C. Addition of copper-based pigments or certain transition metal salts should be avoided without an appropriate antioxidant package because these accelerate oxidative degradation. The product should not be blended with random or impact copolymers where low-temperature impact or transparency is required because the higher crystallinity of the homopolymer will reduce both properties when evaluated by ISO 179-1/1eA at −20 °C and by ASTM D1003 haze. The processing window for controlled-rheology fibre grades is narrow, with melt temperature deviations above ±5 °C causing filament breaks; that operational boundary must be reflected in extruder zone control calibration.