Papers by Keyword: SEBS

Abstract: The study involves the use of high density polyethylene (HDPE) as a filament for 3D printing. Considering the warpage and adhesion problem of HDPE on the build plate during 3D printing, this was addressed through the incorporation of wood flour compatibilized with styrene-ethylene-butylene-styrene grafted maleic anhydride (SEBS-gMAH). The composite wood-HDPE (cHDPE) was studied to observe warpage changes. Using different SEBS, heat bed parameters and identification of the suitable print heat beds for HDPE was conducted. Results from the mechanical testing show that the compressive strength and elastic force of virgin HDPE (vHDPE) increases with infill percentage, while the same properties for cHDPE increases up to 50% infill density/percentage then decreases as it approaches 100% infill percentage. Digital microscopy imaging shows that poor layer adhesion initiated the poor compressive performance of cHDPE. Warp studies reveal that wood flour significantly decreases warping of HDPE by 42.88% at 50% infill density. While different SEBS brands show similar effectiveness as heat beds in reducing warping of HDPE during printing.

Abstract: To improve the compatibility of montmorillonite (MMT) with polymer. A kind of organic intercalation agent was applied in the intercalating organic modification of montmorillonite (OMMT) through ion exchange method, and a kind of silane coupling agent was further used to do the organic treatment. The SEBS/OMMTs composites were also prepared by melt blending. Structure and characterization of the modified MMTs were investigated by Fourier Transform infrared (FT-IR), wide angle X-ray diffraction (WAXRD), and the thermal stability were characterized by Thermogravimetric analysis (TGA). The dispersion status of MMTs were evaluated by scanning electron microscope (SEM) and the composites were tested by universal material testing machine. The FTIR results initial displayed that OMMTs had the absorption peak of organic functional groups. The XRD results showed that compared to Na⁺-MMT(1.47 nm), the layer spacing of H-OMMT increased to 3.27 nm, the above two results showed the organic modification of MMT had succeed. The results of TGA showed that OMMTs had a weight loss of organics. The SEM demonstrated that H-OMMT had the best dispersion status in SEBS matrix, and Na⁺-MMT was the worst.

Abstract: A kind of intumescent flame retardant (IFR) were used for flame retarding of oil-extended hydrogenated styrene-butylenes-styrene (O-SEBS). The samples were systemically characterized by limited oxygen index (LOI), vertical burning test (UL-94), and scanning electron microscopy (SEM); Thermogravimetric (TG) analysis. The results showed that the IFR retardant can promote residual chars with multi-micro holes on the surface of SEBS to inhibit flame; with 45% IFR content, the LOI is 28.3 and flame retardant level is UL-94 classification of V-0, with no dripping. The morphological structures observed by SEM demonstrated that higher IFR content promote to form larger and compact films cover on bubbles of the intumescent char layer. The TG data revealed that the IFR could change the degradation behavior of the O-SEBS, enhance the thermal stability and increase the char residue, The tensile strength of all the O-SEBS/IFR blends had the tensile strength of more than 4MPa and the elongation of more than 850%.

Abstract: Organomodified layered silicates and silicas have been incorporated in thermoplastic elastomers such as styrene-ethylene-butylene-styrene copolymers (SEBS) and polyurethanes (PU) in order to improve mechanical properties - especially tear strength. The organically modified layered silicates used were Cloisite® 30B, a montmorillonite modified with a ternary ammonium salt with hydroxyls as end groups and Nanofil®2 which is organically modified by long chains of hydrocarbon and benzyl groups. Sepiolite, a natural clay with fibrous morphology was also used. The silicas incorporated are Aerosil 300, hydrophilic fumed silica and Aerosil R202, hydrophobic fumed silica. nanoparticles are incorporated between 1 and 5 weight percent. A compatibilizer SEBS grafted with maleic anhydride has been incorporated in some of the formulations for a better dispersion of some of the nanoparticles. Different ways of incorporation have been investigated. For SEBS formulations, melt blends of SEBS pellets and clays have been prepared with an internal mixer and then films have been casted. For polyurethanes, solvent blending of polyols and clays were carried out in a vessel and then, compression molding of the blend with diisocyanates was made to synthesize polyurethanes. Materials have been compared on the basis of normalized tear test and sequenced tensile test. Mechanical parameters, as stabilization ratio (Mullins effect) and viscoelastic ratio, have been defined by integration of the stress-strain curves obtained. An interesting improvement of tear strength was observed for modified materials.

Abstract: SEBS (styrene-ethylene/butylene-styrene) is a hydrogenated SBS used as a compatibilizer of other thermoplastic or as a blend to improve the properties (mainly impact). There is very little information about SEBSs research, independent of other materials. This study focuses on a blend from the providers SEBS extreme hardness (50% Shore-A 5 and 50% Shore-A 90) in order to analyze the miscibility of mixed materials from the storage of 2 references only. It has been used the thermoplastic elastomer Megol TA® SEBS, whose characteristics make it special due to the wide range of hardness and transparency, and can be obtained blend for industrial applications where nowadays liquid silicone rubber is used. Next step is rheological characterization of the blend, analyzing the viscosity for subsequent mathematical modeling. Finally, in order to reproduce the rheological behavior of materials during the injection process, Autodesk Moldflow Inside 2010 CAE (Computer Aided Engineering) tool has been used with Cross-WLF model parameters, and compared with tests injected.

Abstract: Dielectric elastomers, a class of electroactive polymers, are specially promising due to their proven high actuation strain and energy density. Their electromechanical response is described by the Maxwell stress, where the level of strain reached depends mostly on the dielectric constant, elastic modulus and applied electric field. Since a decrease in modulus can enhance the elastomer response, swelling in appropriate solvents, transforming them into gels may enhance actuation. Tri-block copolymer gels offer a large range of possibilities since the mechanical properties and electroactive behaviour of these physically crosslinked materials can be adjusted by varying the polymer concentration, morphology and molecular weigh between crosslinks. In this work efforts were undertaken in reducing the elastic modulus by selective swelling of the elastomer midblocks with an organic oil. Strain responses to static and dynamic electrical stimuli were considered and, in particular, the effect of the frequency on the mechanical efficiency was investigated in detail. A simple theoretical model describing the frequency response was formulated.