Bada AG supplies the compound BADAFLEX® SEBS-Comp. TPE-S 90A 1016 as a styrene-ethylene/butylene-styrene block copolymer grade with nominal hardness of 90 Shore A. The 1016 suffix is the manufacturer’s internal modification index within the BADAFLEX TPE-S range; the base polymer is a saturated SEBS triblock, and the formulation is understood to contain hydrocarbon oil, polyolefinic reinforcing components, and stabilizers. Because the elastomeric mid-block is saturated, the material does not depend on butadiene double bonds for elastic recovery. This structural feature places the product in the TPE-S class rather than in an unsaturated SBS compound or a dynamically vulcanized TPV. The grade is supplied as free-flowing pellets for injection moulding and extrusion on conventional polyolefin equipment. Hardness is measured according to ISO 868 or ASTM D2240 on conditioned plaques after the specified dwell time. Published data for this specific configuration is limited; density, tensile properties, tear resistance, and compression set should be taken from the manufacturer’s technical datasheet before tooling or specification decisions.

Application contexts for a 90 Shore A SEBS compound include grips, seals, grommets, cable jackets, flexible connectors, protective boots, and soft-touch overmoulds on polypropylene or polyethylene substrates. The hardness position is used where a 70 Shore A product may deform excessively under clamping load and a 95 Shore A product may reduce sealing compliance or tactile softness. In two-component injection moulding, the compound is normally processed as the second shot over a pre-moulded substrate; interfacial bond strength is governed by substrate cleanliness, substrate temperature, and melt front velocity. For automotive interior parts, fogging and volatile organic compound behaviour are assessed by ISO 6452 and VDA 278 when the grade is qualified for the application. Without a supplier-issued certificate, the statement that this 1016 variant meets a specific OEM specification cannot be made.

Differentiation from other products in the BADAFLEX line is primarily by Shore hardness, flow length, tensile modulus, and compression set. A lower-hardness variant may require less injection pressure and may show higher surface tack; a higher-hardness variant may improve scratch resistance but may require higher melt temperature and clamp force. Compared with unsaturated SBS compounds, SEBS compounds exhibit lower sensitivity to ultraviolet embrittlement and thermal chain scission. Compared with TPV grades, SEBS compounds generally do not match compression set resistance at 125°C or hot-oil resistance; however, they remain melt-processable without a cure stage and permit direct regrind use within defined limits.

How Does the Saturated SEBS Mid-Block Affect Weathering and Thermal Aging Relative to Unsaturated SBS or TPV Grades?

Ultraviolet and oxidative stability arise from the absence of main-chain unsaturation in the ethylene/butylene mid-block. In unsaturated SBS compounds, residual double bonds act as initiation sites for ozone attack, oxidative chain scission, and loss of elongation. The saturated SEBS structure therefore permits extended outdoor exposure with less dependence on antiozonant packages. Accelerated weathering is assessed by ISO 4892-2 or ASTM G155; retained elongation or delta-E after 1000 h of exposure must be taken from the grade-specific datasheet. In processing, SEBS is fully thermoplastic; unlike a dynamically vulcanized TPV, the compound can be reground and reprocessed within controlled limits, although repeated heat history increases oxidative degradation and shifts viscosity.

Mechanically, SEBS compounds at 90 Shore A typically show lower compression set resistance than high-performance TPV grades at temperatures above 100°C. Compression set is measured after 22 h at 70°C, 100°C, or 125°C using ISO 815-1 or ASTM D395; for standard SEBS formulations the value may increase rapidly as the test temperature approaches the polystyrene endblock glass transition. The processing advantage is the absence of a vulcanization stage, which reduces cycle time and permits regrind use in non-appearance parts. If long-term sealing force retention at 125°C in air or oil is required, a TPV or silicone may be selected unless grade-specific data support the SEBS compound.

When injection moulders transfer from polypropylene homopolymer to the BADAFLEX TPE-S 90A 1016 compound, barrel temperature profiles and screw rotation should be adjusted for shear heating. Typical SEBS compounds of this hardness are processed with melt temperatures between 180°C and 230°C; lower settings may be used for thin-wall parts and higher settings for overmould adhesion. A start-up profile may be set at 180°C rear, 190°C centre, 200°C front, and 200°C nozzle, followed by viscosity and gate freeze-off validation. Moisture absorption is lower than in polyester-based TPU or polyamide, but pre-drying is recommended at 80°C for 2 h to 4 h in a desiccant dryer when storage humidity exceeds 60% RH. Residual moisture should be kept below 0.05% to prevent splay and surface defects.

On vertical clamp injection moulding machines with shut-off nozzles, screw back pressure of 5 bar to 15 bar and injection speeds of 20 mm/s to 80 mm/s are commonly used for TPE-S grades of similar hardness. Mould surface temperatures between 30°C and 60°C support adequate skin formation and release. Clamp force is normally calculated at 0.5 t/cm² to 0.8 t/cm² of projected area, although low-viscosity SEBS grades may require less. Hot runner systems should use free-flow channel geometries with low shear; dead spots and unheated sprue tips can cause premature cooling and inconsistent shot size. For profile or tubing extrusion, a single-screw extruder with a compression ratio of 2.5:1 to 3.5:1 and screw L/D of 25:1 to 30:1 is typically used; downstream calibration must account for elastomer shrinkage and die swell.

Batch-to-batch viscosity variation is relevant for multi-cavity tools with narrow gate dimensions. On production-scale compounding lines, SEBS compounds are melt-mixed on twin-screw extruders with L/D ratios of 40:1 to 52:1; hydrocarbon oil is injected in multiple zones to avoid phase inversion and reduce torque spikes. Pellet geometry affects feeding stability in single-screw extruders and injection moulding machines. Cylindrical pellets with irregular cut length may cause screw slip; spherical or lenticular pellets improve feed-throat entry. When regrind is added at 10% to 20% by weight, viscosity and colour shift may remain acceptable, but higher regrind content increases the risk of black specks and surface defects after repeated heat history. The 1016 variant should be stored in sealed containers at 10°C to 30°C; prolonged storage above 40°C may cause pellet blocking and antioxidant depletion.

The 90 Shore A Hardness Plateau and Its Consequences for Seal Compression Set and Tear Resistance

At 90 Shore A, the compound is in the upper half of the TPE-S hardness range. The indentation hardness value is not a direct measure of tensile strength or modulus but is derived by ISO 868 or ASTM D2240. Density measured by ISO 1183-1 for SEBS compounds in this hardness class generally falls between 0.88 g/cm³ and 1.10 g/cm³ depending on filler and oil content; the exact value is grade-specific. For SEBS grades in this hardness class, tensile strength measured per ISO 37 or ASTM D412 commonly falls between 5 MPa and 15 MPa, with elongation at break between 300% and 600%. These ranges depend on oil content, polystyrene endblock fraction, and filler package. Published data for this specific configuration is limited; class-average values should not be used for finite element analysis or final safety-factor calculation.

Tear strength measured by ISO 34-1 Method B or ASTM D624 die C is typically in the range of 25 kN/m to 60 kN/m for SEBS compounds near 90 Shore A. Abrasion resistance is moderate when compared with TPU; the saturated mid-block provides lower coefficient of friction than highly plasticized PVC but may require surface texturing to avoid tack. The 1016 designation should be checked for oil extension level and filler content because visual appearance, surface finish, and overmould bond strength vary among variants even within the same hardness class. At this hardness, gate blush and jetting are more likely than at 50 Shore A because viscosity is higher; melt temperature and injection speed should be raised in controlled steps while monitoring splay and flash.

The rheological response of SEBS compounds at 90 Shore A is strongly shear-thinning. Capillary rheometry per ISO 11443 typically shows apparent viscosity decreasing with increasing shear rate; high shear at the gate may improve flow length but excessive shear may create melt fracture. Spiral flow length under specified pressure and wall thickness is a useful comparison among 90A grades but should not be used alone to predict filling of complex parts. For thin-wall sections below 1 mm, verification at 220°C and 50 MPa injection pressure is advisable before tool release. Published data for this specific configuration is limited.

Overmoulding onto polypropylene represents one of the most sensitive processing boundaries for this product class. Adhesion to polypropylene is not achieved by covalent bonding; it depends on interdiffusion and compatibility between the SEBS compound and the polyolefin substrate. The substrate surface must be free of mould release, and melt temperature at the interface is typically maintained above 200°C for effective molecular contact. If the substrate is too cold, bond failure may be cohesive in the substrate or adhesive at the interface; if the melt is too hot, PP deformation or gloss loss may occur. On production-scale two-shot moulds, mould temperature uniformity within ±5°C is critical because SEBS compounds have a narrow re-melt window for overmoulding. Published data for this specific 1016 configuration is limited; process engineers should validate by tensile pull-off testing according to the designated OEM standard or ISO 527-1 if applicable.

Failure modes observed on production lines with TPE-S compounds of this hardness are frequently related to moisture, shear heating, or regrind variability. Splay, silver streaks, and edge delamination on moulded parts typically indicate residual moisture above 0.05% or excessive melt temperature. Burn marks at the gate or local yellowing indicate trapped air or decomposition products in the hot runner. Short shots and flow lines in multi-cavity tools may be caused by insufficient melt temperature, undersized gates, or screw recovery exceeding the cooling time. The use of general-purpose check rings with excessive clearance can cause melt leakage and inconsistent shot size; a ball check or ring check assembly with verified wear clearance is required. When these defects occur, process variables should be changed one at a time while recording cushion position, switchover pressure, and part weight. Additive compatibility must also be verified before modifying the compound. Halogenated flame retardants or strongly acidic purge compounds should be avoided unless specifically approved by the supplier; decomposition products may catalyse degradation at processing temperatures above 230°C. Silicone oils used as mould release can migrate to the surface and reduce overmould adhesion; if release agents are required, they should be applied only to non-bonding regions.

When Food-Contact or Medical-Grade Compliance Is Required for the 1016 Variant

The base SEBS polymer can be produced to meet specific food-contact and medical-grade requirements, but the compound as supplied may contain oil, stabilizers, and processing aids that influence regulatory status. The statement that BADAFLEX® SEBS-Comp. TPE-S 90A 1016 complies with Regulation (EU) 10/2011, FDA 21 CFR 177.1810, or USP Class VI must be confirmed against the product-specific certificate. For repeated-use food-contact articles, overall migration is tested according to EN 1186, and specific migration of additives is required. For medical devices, cytotoxicity per ISO 10993-5 and subsequent biocompatibility endpoints are device-dependent. The manufacturer’s regulatory affairs documentation should be requested before using the 1016 variant in food-contact or medical applications. RoHS compliance is assessed under 2011/65/EU; REACH obligations apply under 1907/2006.