Romira ROMILOY 2700 is an unfilled acrylonitrile-butadiene-styrene (ABS) injection moulding grade supplied as cylindrical pellets in natural, black, and matched-colour formulations. The grade is positioned in the medium-impact, high-flow segment of the Romiloy ABS portfolio, meaning it is specified where filling of thin-wall geometries and surface reproduction are more critical than extreme low-temperature ductility. Typical values from supplier technical literature place density at 1.04–1.06 g/cm³ when measured under ISO 1183-1, melt volume-flow rate at 20–25 cm³/10 min under ISO 1133-1 at 220 °C/10 kg, tensile modulus at 2200–2500 MPa under ISO 527-2, Charpy notched impact strength at 20–25 kJ/m² under ISO 179-1/1eA, and Vicat softening temperature B50 at 94–98 °C under ISO 306. These are not independent quality-control limits; they are typical batch-centre measurements that vary with pigmentation, moisture content, gate geometry, and moulded-specimen orientation. The material is principally used for electronic housings, small appliance bodies, and interior trim components that are injection moulded with wall thicknesses below 2.5 mm and require high filling ratios from hot-runner or cold-runner tooling.

Melt Rheology and Injection Moulding Process Boundaries

Material handling on injection moulding lines should begin with dehumidified-air or desiccant drying at 80 °C for 2–4 h; the moisture content of melt-processed pellets is maintained below 0.10 %. Hydrolytic degradation of the butadiene phase at melt temperatures above 240 °C reduces Charpy impact and surface gloss, and produces splay at the gate. Melt-temperature interlocks are usually set at 230–260 °C, with mould-wall temperatures of 40–80 °C. Higher mould temperatures above 80 °C increase weld-line strength in screw bosses and snap-fit features but extend cycle time and can induce sink marks in ribbed sections. Cylinder nozzle geometry with a reverse-taper shutoff is standard; free-flow nozzles may drool at the upper end of the melt window. Screw recovery is set to maintain a cushion of 3–5 mm, and back pressure of 50–120 bar is applied to homogenize colourant dispersion. Fill speeds are adjusted to maintain a flow-front velocity of 100–300 mm/s; slower speeds reduce shear heating and permit gas evacuation through vents of 0.02–0.05 mm channel depth. Insufficient venting causes diesel-effect burn marks at the end of flow paths, especially in closed-cavity tools without perimeter relief. On high-cavitation tooling with hot-runner systems, hot-runner tip temperatures above 260 °C accelerate yellowing and generate visible cold-slug contamination at gate entry.

For thin-wall electrical enclosures with nominal wall stock below 1.5 mm, ROMILOY 2700 is frequently processed on machines with clamp force calculated at 0.40–0.60 t/cm² of projected mould area. Snap-fit features exploit tensile stress at yield of 40–48 MPa and elongation at yield of 2.0–2.8 % under ISO 527-2, but gate placement must avoid jetting because the high melt-volume flow encourages unstable flow through restricted gates. Flammability classification for natural and black grades is typically UL 94 HB at 3.0 mm; thinner sections or colour concentrates can alter the rating, so final certification must be confirmed on the actual moulded part. For appliance components assessed under IEC 60695-2-12, glow-wire ignition temperature is strongly thickness-dependent. Published supplier data for this specific grade in glow-wire configurations is limited, and end-product validation is required before use in unattended appliance enclosures.

What Limits Moisture Uptake and Drying Stability Before Processing?

Saturated moisture regain of ABS is low compared with polyamide or polycarbonate; however, regrind stored in open containers at relative humidity above 60 % can reach surface moisture contents of 0.2–0.4 % within 24 h. At these values, injection moulding produces surface splay, streaking, and reduced weld-line strength. Drying in a desiccant-bed dryer with dew point below -30 °C is preferred over hot-air hopper dryers because the latter cannot return surface moisture to a stable sub-0.10 % condition. Predrying residence time beyond 4 h at 80 °C does not significantly increase melt stability but raises energy consumption and can promote pellet bridging in conical drying hoppers. Blends with regrind are typically limited to 20–30 % regrind fraction unless injection trial data demonstrate equivalent Charpy impact retention and colour uniformity. Melt residence time after drying should be minimized; hold-up time exceeding 10 min at 250 °C causes visible yellowing and molecular-weight degradation.

When Charpy Notched Impact Above 25 kJ/m² Is Required, Higher-Impact ABS Grades Replace ROMILOY 2700

ROMILOY 2700 differs from extrusion-grade and high-impact ABS types primarily in its flow-impact balance. Compared with general-purpose ABS of equivalent melt flow, it maintains surface hardness and dimensional stability but exhibits lower Charpy notched impact than high-impact injection moulding grades, which can exceed 30 kJ/m² at 23 °C under ISO 179-1/1eA. At low temperatures, the notched impact of ROMILOY 2700 declines; published supplier data for notched Charpy at -30 °C is not consistently available for every colour lot, so application qualification must include cold-impact testing on the actual part. When a component is exposed to repeated impact loading or requires ductile failure below 0 °C, high-impact ABS or a polycarbonate/ABS blend is preferable. When the processing requirement exceeds 25 cm³/10 min melt volume-flow rate, ROMILOY 2700 may be substituted for less fluid ABS grades in thin-wall moulds, but the trade-off is a measurable reduction in environmental stress-crack resistance to low-polarity oils and cleaning fluids. PC+ABS blends may also provide Vicat B50 values of 110–130 °C under ISO 306, but generally at lower melt-flow and higher density.

Relative to glass-fibre-reinforced ABS grades, ROMILOY 2700 produces lower melt viscosity and lower tool wear, but it does not provide the flexural modulus above 3000 MPa or heat deflection temperature above 100 °C associated with short-glass ABS. When load-bearing brackets or structural housings require flexural modulus above 3500 MPa, reinforced ABS or PC+ABS should be selected. Conversely, for thin-wall parts with long flow paths and fine surface grain, ROMILOY 2700 has a melt-flow advantage over reinforced grades because glass fibres increase viscosity and can promote anisotropic shrinkage, surface roughness, and gate fouling in hot-runner systems.

When chemical resistance is evaluated, ROMILOY 2700 follows the expected ABS behaviour: the material resists dilute aqueous acids and alkalis, aliphatic hydrocarbons, and most alcohols at room temperature, but it is incompatible with ketones, esters, chlorinated solvents, and aromatic hydrocarbons. Environmental stress cracking can be evaluated using ISO 22088-2 bent-strip procedures at constant strain; moulded features with high residual stress, such as press-fit pins and self-tapping screw bosses, are more susceptible than flat specimens. Exposure to methyl ethyl ketone or ethyl acetate at room temperature causes visible crazing within minutes, so solvent bonding should use cyanoacrylates or two-component acrylic adhesives validated for ABS. Stress-relief annealing at 60–70 °C for 1–2 h after machining reduces solvent crazing in bonded joints but does not eliminate it.

For outdoor applications requiring weathering stability, ASA grades rather than ROMILOY 2700 are specified. The butadiene rubber phase in ABS is susceptible to photo-oxidative scission under UV-A exposure; surface chalking and yellowing typically precede embrittlement. Xenon-arc weathering according to ISO 4892-2 is used to rank colour change and gloss retention, but published data for ROMILOY 2700 in custom colours is limited. Exposed components should use UV-stabilized ASA or a paint system with adequate UV barrier. This substitution is a material-family difference: ABS retains a cost and flow advantage but lacks the weatherability and lower yellowing index of ASA grades.

Thermal Performance Under Constant Mechanical Load

Heat deflection temperature under 1.80 MPa load typically falls between 90–96 °C when tested by ISO 75-2; the B50 Vicat softening temperature of 94–98 °C is not a continuous service temperature. Continuous exposure to air at 70–80 °C can cause gradual gloss loss and colour shift; above 90 °C, mechanical properties decay as acrylic-styrenic matrix relaxation and rubber-phase oxidation proceed. For gears, brackets, or lamp housings in proximity to incandescent sources, published data for this specific configuration is limited, and long-term thermal ageing at the maximum service temperature should be validated by part-specific accelerated testing. Dimensional stability under thermal cycling can be assessed with ISO 11359-2 thermomechanical analysis; the linear coefficient of thermal expansion for unfilled ABS is approximately 80–110 × 10⁻⁶ K⁻¹, causing noticeable gap changes in assemblies exposed to temperature swings above 60 °C.

Regulatory Documentation and Supply-Condition Variability

Compliance documentation for ROMILOY 2700 is supplied according to product-specific declarations, not generic statements. The grade is generally positioned to support EU RoHS Directive 2011/65/EU, REACH Regulation (EC) No 1907/2006, and packaging waste directive 94/62/EC; however, the presence of antimony or brominated flame-retardant additives in colour-matched variants must be confirmed because non-black custom colours can carry different stabilizer systems and may fall under separate regulatory classifications. Polymer marking under ISO 11469 is >ABS< for unfilled ABS. Food-contact status under EU 10/2011 or FDA 21 CFR 177.1020 is not routinely assigned to every supply form; if migration-sensitive applications are contemplated, the customer must obtain lot-specific certification and assess additive migration kinetics in the polymer matrix. Supply-condition variability includes pellet moisture, lot-to-lot colour difference measured as Delta E under ISO 11664-4, and residual monomer levels that affect odour in enclosed cabin interiors.

Optimising High-Shear Dispersion and Weld-Line Strength Through Gate Design

Optimising high-shear dispersion in ROMILOY 2700 starts with gate type and land length rather than screw speed alone. Direct pin gates with land lengths over 1.0 mm increase pressure drop and shear heating; higher melt temperatures at the gate can create local gloss variation on textured surfaces. Tunnel and submarine gates used on high-cavitation moulds should be sized to maintain a shear rate below 50,000 s⁻¹ at maximum fill velocity, because excessive shear initiates rubber-phase agglomeration and reduces Charpy impact. Weld-line strength is maximized when melt fronts meet at temperatures above 220 °C; cold stagnation zones below 200 °C produce visible weld lines and lower fracture energy. On parts with multiple gates, sequential valve-gate sequencing expands the filling window and prevents entrapment of gas at the last cavity to fill. In pre-compounded custom colours, twin-screw compounding on machines with L/D ratios of 32:1–40:1 is typical; this compounding step can shift melt flow slightly compared with natural pellets, and injection moulders should request lot-specific ISO 1133-1 data for masterbatch-modified material.

ROMILOY 2700 is not optimized for profile extrusion or thick-wall sheet. Extrusion-grade ABS grades have higher molecular weight and higher melt strength to resist draw-down, while ROMILOY 2700 is designed for injection moulding where high melt fluidity and short cooling cycles dominate. If sheet extrusion is required, an extrusion ABS with lower melt-volume flow and higher elongational viscosity should be selected. Published data for this specific configuration is limited; processing outside the primary injection moulding window is not recommended without rheological characterization.