INEOS Styrolution Terluran E-115 is an acrylonitrile-butadiene-styrene copolymer assigned to the high-flow, medium-impact segment of the Terluran injection-moulding range. The grade is supplied as natural or pre-coloured pellets and is specified for components in which melt delivery into thin sections and subsequent chromic acid etching for electroplating control part acceptance. Density is 1.04 g/cm³ according to ISO 1183-1:2019; melt volume-flow rate is 14 cm³/10 min at 220 °C under 10 kg load according to ISO 1133-1:2022. The molecular architecture is balanced to produce a controlled butadiene particle-size distribution required for uniform etch pit formation in decorative chromium-plating lines. Unlike general-purpose ABS grades, Terluran E-115 is not optimised solely for mechanical property retention; the specification also includes plateability criteria such as low internal moulding stress and reproducible etch response.

The grade designation sits within the Terluran E series, which denotes electroplating-optimised feedstock rather than general-purpose or high-impact ABS. The primary polymer variables are the styrene-acrylonitrile matrix viscosity, the butadiene rubber phase volume fraction, and the rubber particle-size distribution. These variables jointly determine both melt rheology and chromic acid etch response. In the molten state, apparent viscosity at 1000 s⁻¹ is sufficiently low to fill multi-gated components, while melt strength remains adequate for ejected parts with wall thickness above 1.2 mm. Published datasheets for the grade focus on injection moulding; no claim of suitability for profile extrusion or thermoforming is made because melt strength and drawdown behaviour fall outside those process windows.

Industrial application data for this grade concentrate on electroplated automotive interior and exterior components, sanitary fittings, cosmetic closures, and consumer electronics trim. In these components, nominal wall thickness is frequently below 2.5 mm, and the polymer must fill complex ribs without excessive residual stress that causes etch over-roughening or blister defects after plating. Processing experience on injection moulding machines of 800–1200 kN clamp force indicates that Terluran E-115 can be processed with lower injection pressure than high-impact ABS grades of similar melt temperature, although published data for specific part configurations is limited. The principal process benefit is a reduction in short-shot rejection on multi-cavity tools when barrel temperatures are maintained between 230 °C and 250 °C.

What controls etch uniformity in chromic acid electroplating of ABS?

The electroplating sequence for ABS grades relies on selective oxidation of the butadiene phase in a mixed chromic acid–sulfuric acid etch bath. Etch bath conditions reported for ABS electroplating grades are typically 380–430 g/L chromium trioxide, 350–400 g/L sulfuric acid, and a bath temperature of 60–68 °C; immersion times are adjusted between 5 min and 15 min depending on part geometry and required adhesion. Terluran E-115 is formulated so that the etched surface develops microcavities with dimensions suitable for palladium–tin catalyst adsorption in the subsequent activation step. If the butadiene phase is too coarse or too finely dispersed, etch depth becomes excessive or insufficient; both conditions reduce peel adhesion after electroless copper or nickel deposition. The grade therefore carries a narrower specification for melt residence time and injection speed than general-purpose ABS, because shear-induced rubber particle deformation in the moulded skin can alter the etch response.

Process-control laboratories typically quantify etch response by weight loss per unit surface area. For ABS electroplating grades, weight loss values in the region of 0.5–1.5 wt% are often targeted before activation, but the exact target depends on the chromium trioxide-to-sulfuric acid ratio and bath ageing. Aged etch baths containing trivalent chromium above 20 g/L lose oxidation capacity and produce non-uniform etch pit density; bath maintenance and regeneration are therefore critical variables. The narrow rubber-phase specification of Terluran E-115 reduces the sensitivity of etch weight loss to minor bath drift compared with general-purpose ABS, but it does not eliminate the need for bath titration and periodic decantation.

Residual stress in the moulded part is a greater process conflict for plating grades than for unpainted ABS. High packing pressure or low mould temperature increases orientation and frozen-in stress, which is released during the hot etch bath and results in localised over-etching or cracking. Process engineers control this through modulated packing profiles, mould temperatures above 50 °C, and gate placement that avoids high shear at the part surface. When electroplated parts are subjected to adhesion pull tests, failure normally occurs cohesively within the ABS substrate or at the metal–polymer interface; for Terluran E-115, substrate cohesive failure is preferred because interface failure indicates insufficient etch depth.

Mechanical and thermal property matrix for mould design

Values are typical for injection-moulded multipurpose test specimens conditioned according to ISO 291:2008. Property retention in moulded parts depends on gate geometry, packing pressure, and cooling rate in the cavity; thin-wall electroplated components often exhibit lower notched impact values because high shear orientation freezes molecular orientation in the flow direction. Designers should treat the tabulated Charpy values as upper bounds for thick sections and not as guarantees for weld-line regions or chromium-plated assemblies.

Moisture control before melt processing is mandatory. Terluran E-115 should be dried in a desiccant dryer at 80 °C for 2–4 h to a maximum moisture content of 0.05 %. Insufficient drying produces splay marks, lowers surface smoothness, and creates microvoids that interfere with catalyst adsorption after etching. Processing experience on single-screw injection units indicates that barrel residence time above 5 min at 250 °C can cause surface degradation appearing as brown streaking and reduced etch consistency. Screw geometry with a compression ratio of 2.0–2.5:1 and a metering zone of 3–4 D is typical for medium-flow ABS, although published data for this specific grade is limited.

Failure modes observed in production-scale drying operations are primarily batch-related. If pellets are dried in trays rather than desiccant dryers, moisture content can vary throughout the batch, producing intermittent splay in later cavities. The use of hygroscopic regrind raises the equilibrium moisture load and may require extended drying; typical regrind addition for plating-grade ABS is limited to 20 % or less to preserve surface quality. Higher regrind fractions risk scatter in etch response because multiple heat histories alter the rubber phase and can generate gel particles.

When melt pressure becomes the limiting factor in multi-cavity tools

Flow length and wall thickness govern the required injection pressure in thin-wall ABS components. Under high shear rates above 1000 s⁻¹, the pseudoplastic behaviour of Terluran E-115 reduces apparent viscosity, but excessive injection velocity increases shear heating and can initiate yellowing at the hot tip. Comparative spiral-flow data for high-flow ABS grades show that melt temperature is more effective than increased mould temperature in extending flow length within the 230–260 °C barrel range. Mould temperatures are normally held between 50 °C and 70 °C for electroplating grades; higher mould temperatures improve surface gloss and reduce frozen-in stress, but they increase cycle time and may promote sink marks on ribs. Gate diameters below 0.8 mm can impose excessive pressure drop and should be avoided for plating-grade ABS unless supported by cavity-pressure measurement.

On injection moulding machines with small clamping force, the lower melt viscosity of Terluran E-115 allows a reduction in hydraulic injection pressure relative to high-impact ABS; however, pressure drop through a small gate remains the dominant bottleneck. For a spiral-flow mould or thin plaque tool, melt pressure transducers located at the nozzle and near the last cavity provide real-time evidence of viscosity shifts. A rise in cavity pressure at constant melt temperature that exceeds 10 % across consecutive shots is often traced to moisture uptake, worn check ring, or unexpected lot-to-lot variation in melt flow.

What separates this grade from general-purpose and high-impact ABS?

General-purpose Terluran GP-22 and high-impact Terluran HI-10 represent different positions in the toughness-flow trade-off. Terluran GP-22 is designed for mechanically loaded unpainted mouldings and can be electroplated with lower consistency because its rubber-phase distribution is not specified for etch uniformity. Terluran HI-10 offers higher notched impact but has lower melt volume-flow rate and demands higher injection pressure for the same flow length. In thin-wall tools, the process window for Terluran E-115 is wider in terms of fill pressure and short-shot boundaries, but the impact strength at sub-zero temperatures is lower.

A direct substitution of Terluran GP-22 into an electroplated part may proceed through the moulding stage without difficulty, but the plated part can show inconsistent adhesion or peeling after thermal cycling because the etch pit population is not optimised. Replacement of Terluran HI-10 with Terluran E-115 is generally not recommended when low-temperature ductility is a safety requirement, such as in exterior door handles or crash-relevant brackets. Conversely, substituting Terluran E-115 for HI-10 in decorative bezels reduces clamp force demand and cycle time, provided that the lower impact toughness remains within the part specification.

Regulatory documentation for Terluran E-115 is available through INEOS Styrolution and typically addresses European REACH registration under EC 1907/2006 and the restriction of hazardous substances under Directive 2011/65/EU for electrical and electronic equipment. These statements refer to the base polymer; finished plated components must be assessed separately because electroplating baths introduce metallic layers that are not covered by the polymer declaration. For automotive applications, material data systems such as IMDS may require a different reporting format, and the moulder is responsible for linking the correct Terluran E-115 grade code to the component weight and recycling category.

Solvent resistance data for ABS indicate general resistance to water, dilute acids, alkalis, and aliphatic hydrocarbons but attack by aromatic hydrocarbons, esters, ketones, and chlorinated solvents. Because electroplated parts may be exposed to cleaning agents and cosmetics residues, the selected plating stack must be tested under the end-use chemical environment. The polymer substrate absorbs low-molecular-weight organic compounds and can undergo environmental stress cracking when simultaneous stress and solvent contact occur. Moulded parts should therefore be stress-relieved or properly packed during injection to avoid tensile surface stress that combines with solvent exposure to produce fissures.

Peel adhesion of electroplated ABS is commonly reported using a peel test in which a narrow strip of the metal layer is separated from the substrate at constant crosshead speed. The measured force per unit width is affected by metal thickness, peel angle, and plating-layer ductility; therefore, comparisons across laboratories require identical specimen preparation. In decorative automotive plating specifications, minimum peel adhesion values in the range of 0.8–1.5 N/mm are often required for copper-based systems, but the exact acceptance limit is customer-specific. Published data for Terluran E-115 adhesion under every plating combination is limited; processors should generate lot-specific test plaques under their own etch and plating chemistry.

Plating lines for ABS components follow a sequence of etch, neutralisation, catalytic activation, acceleration, electroless plating, and electrolytic build-up. Neutralisation in a reducing solution such as sodium metabisulfite removes residual chromium from the etched surface; activation employs a palladium–tin colloidal bath that deposits palladium islands in the microcavities formed by the etch. After acceleration, electroless copper or nickel forms a conductive layer, and subsequent electrolytic copper, nickel, and chromium layers build the decorative and corrosion-resistant coating. Adhesion testing on plated ABS is commonly performed by tape pull or thermal shock methods, but acceptance limits are specific to the end-use specification.

Terluran E-115 is not intended for continuous outdoor use without a protective metallic or organic topcoat. Unprotected ABS undergoes photo-oxidative yellowing and loss of impact strength under UV exposure. The grade is not resistant to aromatic hydrocarbons, ketones, esters, or chlorinated solvents; contact with these fluids should be prevented during moulding and plated-part service. Electroplated parts may exhibit thermal cycling limits governed by the metal-polymer expansion mismatch, and plated assemblies should be validated under customer-specific thermal shock conditions. For food-contact or drinking-water applications, specific compliance under FDA 21 CFR 177.1020 or regional drinking-water approvals must be confirmed with the supplier and lot-specific certification because additive packages and colour concentrates can alter the regulatory status.