Medical device processors running multi-layer co-extrusion lines with single-screw extruders in the 24:1 to 30:1 L/D range have evaluated Kraton™ G2708 GU-N as the styrenic block copolymer layer in fluid transport assemblies where post-autoclave clarity and low extractables are part of the validation file. In this configuration the compound is blended with polypropylene homopolymer at 60–80 wt% SEBS compound to 20–40 wt% PP homopolymer; a processing stabiliser package of 0.05–0.15 wt% hindered phenolic antioxidant is added under nitrogen-blanketed twin-screw compounding at 200–230°C. Compliance evidence typically includes FDA 21 CFR 177.1810 for styrenic block copolymers in repeat-use rubber articles, USP Class VI acute systemic injection and intracutaneous reactivity data, ISO 10993-5:2009 cytotoxicity evaluation, and sterilisation validation under ISO 11135:2014 ethylene oxide or ISO 17665-1:2006 steam. The downstream production process is usually a two-stage operation: first, melt filtration through a 100–150 mesh screen pack to remove gel particles above 80–120 µm; second, extrusion of tubing with wall thickness 0.6–1.2 mm at melt temperature 180–210°C. Post-extrusion annealing at 80–100°C for 30 min is used to reduce frozen-in orientation that otherwise induces kinking at bend radii below 2× outer diameter. Terminal finished product types include pressure monitoring tubing, peristaltic pump segments for dialysis equipment, syringe plunger tips, and drip chamber seals.

What Prevents Delamination When a 35 Shore A SEBS Compound Is Overmoulded onto PC/ABS Substrates?

Because peel strength between a soft TPE-S and PC/ABS depends on interfacial temperature rather than barrel settings, trials on vertical rotary injection moulding machines with clamp force between 800 kN and 1,600 kN have used Kraton™ G2708 GU-N as the soft-segment component in a TPE-S formulation at 30–50 wt% SEBS compound, 10–20 wt% polypropylene, 20–40 wt% white mineral oil, and 0–10 wt% functionalised SEBS or polybutene-1 as a flow and tie modifier. The processing window requires pre-drying at 70°C for 2 h when ambient relative humidity exceeds 60%, because residual moisture leads to surface splay and weakens the bond line to PC/ABS below 2.5 N/mm peel strength. Amine-based antistatic additives above 0.2 phr should be avoided because they migrate to the interface during environmental cycling and lower peel strength. Barrel temperatures are maintained at 200–230°C, the substrate is heated to 100–140°C at the interface before the second shot, and holding pressure is held at 30–50 MPa for 5–10 s. Compliance is normally demonstrated with REACH Article 33 SVHC disclosure, RoHS 2011/65/EU Annex II restricted substance screening, and flow characterisation under ISO 1133-1:2022; adhesion evaluation is performed by ISO 527-1:2019 tensile testing of overmoulded plaques and by environmental cycling at 85°C/85% RH for 168 h. Terminal finished product types include power-tool soft grips, handheld consumer electronics overmoulds, toothbrush handles, and hand-tool cushions.

Low SEBS Addition Alters Ductile-Brittle Transition in PP

In homopolymer polypropylene compounding on a co-rotating twin-screw extruder with an L/D of 40:1, the incorporation of Kraton™ G2708 GU-N at 5–15 wt% lowers the ductile-brittle transition temperature without dropping melt flow below the specification floor. The compound is introduced via a side feeder after the PP melt has reached 200°C; screw speed is maintained at 400–600 rpm with specific energy input of 0.18–0.25 kWh/kg, followed by underwater strand pelletising. The formulation is PP homopolymer 80–94 wt%, SEBS compound 5–15 wt%, antioxidant masterbatch 0.1–0.3 wt%, and optionally linear low-density polyethylene 0–5 wt% to improve gloss retention. Comparative data are generated under ASTM D256-23 Izod notched impact at 23°C and -20°C, ASTM D638-22 tensile properties, and ISO 1133-1:2022 melt flow rate at 230°C/2.16 kg. Downstream production includes injection moulding of thin-wall parts with tonnage calculated at 3–5 kN/cm² projected area, using mould temperatures of 20–60°C. Terminal finished product types include automotive interior trim, appliance housings, storage containers, and battery cases. Published data for this specific compound in PP is limited; the values below represent comparable SEBS impact-modifier benchmark ranges and should be confirmed by line trials.

Hot-melt adhesive formulation lines using 200–500 L sigma-blade mixers and slot-die coating at 160–190°C use Kraton™ G2708 GU-N as the elastomeric backbone in pressure-sensitive adhesives where permanent tack and low-temperature mandrel bend are specified. The elastomer addition ratio is 15–25 wt%, combined with 40–60 wt% hydrogenated C5/C9 hydrocarbon tackifier, 20–30 wt% paraffinic or naphthenic oil, and 0.5–1.0 wt% hindered phenolic antioxidant. Mixing is performed under nitrogen blanket for 60–120 min until a Brookfield Thermosel viscosity plateau is reached; the adhesive is then pumped through a heated transfer line to a slot-die coater at 175–185°C. Compliance for dry food-contact applications is anchored to FDA 21 CFR 175.105 adhesives, and adhesive performance is tested under ASTM D3330/D3330M peel adhesion and ASTM D3654/D3654M shear adhesion failure temperature. Aromatic oil content above 5 wt% should be avoided because it disrupts the styrene domains and reduces cohesive strength; PET carrier webs require corona treatment of 38–42 dyn/cm because the non-polar SEBS surface shows limited wetting. Terminal finished product types include hygiene article construction adhesives, disposable medical dressing fixation layers, label stocks, and carton sealing hot melts.

When IEC 60332-1 Demands Halogen-Free Jacketing with Low-Temperature Ductility

In halogen-free cable jacketing, Kraton™ G2708 GU-N is formulated at 20–40 wt% with polypropylene/polyethylene carrier 20–40 wt%, magnesium hydroxide or aluminium hydroxide flame retardant 30–50 wt%, and processing lubricant 1–3 wt%. The downstream production sequence starts with flame-retardant predispersion in a co-rotating twin-screw compounder at 150–180°C to prevent screw build-up, followed by pelletising and final jacketing extrusion on a 45–90 mm single-screw extruder with L/D 25:1 to 30:1. Melt temperature in the die is held at 150–190°C; a 80–120 mesh breaker plate removes agglomerates above 100 µm. Compliance is verified against IEC 60332-1-2:2015 vertical flame propagation, IEC 60754-1 halogen acid gas content, RoHS 2011/65/EU Annex II, and UL 1581 for tensile elongation before and after 7 days at 136°C. The low-temperature ductility of the jacket is checked by IEC 60811-401 cold bend at -40°C. Terminal finished product types include flexible appliance cords, automotive harness sheathing, photovoltaic cable jackets, and industrial control cable sheaths.

Microcellular Injection Moulding Targets for SEBS-Based Footwear Soles

Foamed SEBS footwear components are produced on injection moulding machines with physical blowing agent dosing or chemical blowing agent masterbatch injection. Kraton™ G2708 GU-N is used at 50–70 wt% with PP 10–20 wt%, mineral oil 10–20 wt%, silica or calcium carbonate filler 10–20 wt%, and azodicarbonamide chemical blowing agent at 0.3–0.8 phr. The production process uses barrel temperatures of 170–200°C, mould temperature 20–50°C, and fast injection speed to promote cell nucleation; part weight reduction of 15–30% relative to solid mouldings is the primary control metric. Published data for G2708 GU-N-specific microcellular expansion ratios remains limited, so line trials should bracket blowing agent content in 0.1 phr steps and record part weight, Shore A hardness under ISO 868:2003, abrasion loss under DIN 53516, and compression set under ASTM D395-21. Compliance for footwear consumer goods typically includes REACH Annex XVII restricted substance screening and RoHS 2011/65/EU restricted metals where electronic components are not present. Terminal finished product types include lightweight sandals, midsoles, insoles, and slipper soles.