Shanghai Pret ABS 3450HI is supplied as a high-impact acrylonitrile-butadiene-styrene terpolymer pellet in which a controlled polybutadiene rubber phase raises notched Izod impact strength at 23 °C to approximately 35 kJ/m² under ISO 180/1A while retaining a melt volume-flow rate of 12 cm³/10 min at 220 °C under a 10 kg load per ISO 1133-1:2022. The 3450HI designation identifies a high-impact variant within the 3450 series that increases elastomer content relative to general-purpose ABS grades. The associated trade-off is expressed in a flexural modulus of 2200 MPa measured by ISO 178 and a heat deflection temperature under 1.8 MPa of 94 °C per ISO 75-2. Because the polybutadiene phase is present at a higher volume fraction, the material is specified for injection-moulded housings, power-tool casings, appliance components, and interior trim substrates that require crack-propagation resistance at room temperature but do not require the continuous heat performance of ABS/PC blends.

What Are the Representative Mechanical and Thermal Property Boundaries?

Representative property values are summarised in Table 1. The notched Izod impact value at 23 °C is approximately 35 kJ/m², but the value drops to 12 kJ/m² at −30 °C, establishing the lower operational boundary for impact-loaded parts. The tensile yield stress of 43 MPa under ISO 527-2/1A/50 is accompanied by an elongation at break of 20%, indicating ductile tensile failure under low strain rate but not guaranteeing ductile failure under triaxial stress at weld lines. The Vicat softening temperature of 98 °C under ISO 306 B50 limits continuous-use temperature in load-bearing applications to approximately 75–85 °C. Published data for long-term heat ageing of this specific grade is limited; therefore, sustained exposure above 85 °C should be validated using end-use mechanical testing according to ISO 178 or ISO 527-2.

Prior to any melt-processing operation, the hygroscopic styrene-acrylonitrile matrix requires pre-drying in a desiccant-bed dryer with a dew point of −30 °C or lower. Moisture uptake above 0.1 wt% produces splay, silver streaking, and a measurable loss of notched impact at knit lines. A drying schedule of 80 °C for 3–4 h is typical for pellets stored in sealed containers. Bags that have been opened for more than 8 h at 60% RH should be dried for 4–6 h. Moisture content should be verified by Karl Fischer titration below 500 ppm before processing. Regrind levels above 30 wt% require a 10 °C reduction in barrel temperature because repeated thermal history accelerates polybutadiene crosslinking and raises melt viscosity.

Melt Rheology and Screw Recovery Behaviour

The melt volume-flow rate of 12 cm³/10 min at 220 °C/10 kg places 3450HI in the medium-flow segment for high-impact ABS. Capillary rheometry at 230 °C indicates an apparent viscosity of approximately 350 Pa·s at 1000 s⁻¹ and 90 Pa·s at 5000 s⁻¹; the shear-thinning response is consistent with a dispersed rubber phase that orients under flow. Screw recovery behaviour on a 120-tonne injection moulding machine with a 40 mm general-purpose screw and L/D 20:1 is stable at back pressures of 0.5–1.5 MPa. The barrel profile from feed to nozzle is recommended at 210 °C to 240 °C, with nozzle temperature not exceeding 250 °C to avoid thermal degradation of the polybutadiene phase. Holding pressure should be set at 50–70 MPa hydraulic depending on gate geometry and wall thickness. Production-scale compounding records indicate batch-to-batch variation in melt volume-flow rate is normally controlled within ±1.5 cm³/10 min; tighter limits may be available for automotive qualification.

Gate sizing for 3450HI follows a wall-thickness-to-gate-depth ratio of approximately 1:0.7 for rectangular edge gates. Submarine gates below 0.8 mm diameter generate high shear heating and can yellow the material at melt temperatures above 240 °C. For a projected area of 500 cm², a clamp force of 1500–2000 kN is typical, corresponding to 3–4 kN/cm². Mould temperatures between 40 °C and 80 °C are acceptable. Lower mould temperatures reduce cycle time but increase frozen-in stress and reduce surface gloss. Higher mould temperatures above 80 °C improve knit-line strength but extend cooling time. On multi-cavity tooling, unbalanced runner systems have been observed to produce a notched Izod variation of up to 8 kJ/m² between first and last cavities; geometrically balanced runners and flow leaders are therefore required for safety-relevant components.

When 3450HI Replaces General-Purpose ABS in Low-Temperature Housings, Property Cliffs Appear Below −30 °C

Substitution of 3450HI for a general-purpose ABS in a housing that experiences impact at −20 °C provides a measurable advantage: the notched Izod value remains approximately 14 kJ/m² at −20 °C, whereas many general-purpose grades fall below 8 kJ/m² under the same condition. Below −30 °C, however, the notched Izod value of 3450HI declines to 12 kJ/m² and the failure mode transitions from ductile hinge-break to brittle crack propagation. Parts designed for service below −40 °C should therefore use an ABS/PC blend or a high-impact ABS with an elastomer phase having a lower glass transition temperature. This boundary is a critical processing limitation because moulded-in stress from asymmetric cooling can shift the ductile-to-brittle transition upward by 5–10 °C. For low-temperature applications, the processing window should be biased toward higher mould temperatures and lower melt temperatures to reduce residual stress.

The Grade Sits Between General-Purpose ABS and ABS/PC Blends in Impact–Heat–Flow Space

Compared with ABS/PC blends, 3450HI avoids the 100 °C drying requirement and the 260–280 °C melt-temperature window of PC-containing formulations, reducing energy input on standard ABS lines. It also avoids the severe melt-flow reduction associated with polycarbonate. However, the grade gives up approximately 16 °C of heat deflection temperature and 18 kJ/m² of notched Izod at −30 °C relative to a mid-range ABS/PC blend. Against high-flow ABS grades used for thin-wall electronic housings, 3450HI exhibits lower melt flow but higher elongation at break under ISO 527-2 and greater knit-line toughness in parts with wall sections above 1.5 mm. The grade is therefore positioned in the middle of the impact–flow–heat triangle: sufficient impact for appliance and power-tool housings, adequate flow for wall sections above 1.5 mm, and heat resistance sufficient for intermittent exposure to 85 °C but not for continuous under-hood automotive use.

Avoid combination with amine-based processing aids, metal stearates at levels above 1 wt%, and prolonged contact with ketones, esters, or aromatic hydrocarbons. The grade is not stabilised for long-term UV exposure; unpainted outdoor use requires an additional UV absorber package. For electroplating and painting, adhesion should be verified because the high rubber content can produce surface roughening during chromic acid etching. Parts specified for outdoor weathering or continuous under-hood exposure fall outside the documented processing and service envelope of this grade.