SEBS Copolymer Research Articles

Design and synthesis of poly(styrene-b-(ethylene-co-butadiene)-b-styrene) anion exchange membranes with high ion conductivity

Poly(styrene-b-(ethylene-co-butadiene)-b-styrene) copolymers (SEBS) have garnered significant attention to develop anion exchange membranes (AEMs) for fuel cells. However, SEBS commodities encounter a formidable obstacle of fabricating high-performance AEMs as thermoplastic elastomer. Herein, a series of poly(styrene-b-butadiene-b-styrene) copolymers (SBS) with high content of 1,4-butadiene units (>90 % of middle block) and variable content of polystyrene (PS, 51.3, 61.6 and 70.7 wt%) has been designed to develop SEBS AEMs with high-strength polyethylene phase via hydrogenation, chloromethylation, quaternization and alkalization. The results demonstrate that high PS content broadens the ion transport channel, improves the ion exchange capacity (IEC) and alkali resistance stability, and substantially boosts the ion conductivity, water uptake and swelling ratio of AEMs. Besides, the high proportion of polyethylene phase from 1,4-butadiene unit of SBS copolymers provides good dimensional stability to the AEMs. Remarkably, the AEMs with 70.7 wt% PS and an IEC value of 3.37 mmol g−1 significantly upgrades the ionic conductivity to ∼190 mS cm−1 at 80 °C. It attains a peak power density of ∼1000 mW cm−2 at 2.09 A cm−2 in a H2/O2 single cell operating at 80 °C. This outstanding performance underscores the promising potential of such SEBS copolymers in the development of high-performance SEBS AEMs for fuel cells.

Toward improving the compatibility of the polypropylene (PP)/acrylonitrile–butadiene–styrene (ABS) blends through the incorporation of SEP and SEBS copolymers

Toward improving the compatibility of the polypropylene (PP)/acrylonitrile–butadiene–styrene (ABS) blends through the incorporation of SEP and SEBS copolymers

Transforming vulcanized styrene–butadiene waste into valuable raw material: an opportunity for high-impact polypropylene production

Polypropylene (PP) compounds with styrene–butadiene rubber residue (SBRr) from the footwear industry were produced, adding styrene-(ethylene–butylene)-styrene (SEBS) as a compatibilizer, with 20% and 30% of styrene (St.). The PP/SBRr and PP/SBRr/SEBS compounds were processed in a co-rotating twin-screw extruder and injection molded. The addition of 30% SBRr did not compromise processability, as torque and melt flow index increased slightly compared to neat PP. Significant increases in impact strength were achieved for PP/SBRr/SEBS (10–20% St.) and PP/SBRr/SEBS (10–30% St.), with gains of 316% and 248% related to PP. The elastic modulus, tensile strength, elongation at break, and Shore D hardness indicated greater flexibility for the PP/SBRr/SEBS, especially in the copolymer with 20% St. When the PP/SBRr system was made compatible with SEBS (30% St.), the elastic modulus, tensile strength, and Shore D hardness increased in relation to the PP/SBRr/SEBS (20% St.). Such behavior suggested that the SEBS copolymer (30% St.) was more effective in increasing the resistance to elastic deformation of the PP/SBRr/SEBS compounds, compared to SEBS (20% St.). The heat deflection temperature (HDT) indicated that even adding high content of SBRr to PP, the HDT was not severely affected, possibly due to its crosslinked character. PP/SBRr compatibilization with SEBS (20% St.) inhibited the PP crystalline peaks, as verified through X-ray diffraction (XRD). Stable morphology was achieved upon 10% of SEBS addition to PP/SBRr, providing proper interfacial adhesion and fine particles, contributing to toughening PP. Acquired results are promising for rubber recycling, aiming to produce high-impact polypropylene for containers and furniture accessories applications.Graphic abstract

Improving the performance of quaternized SEBS based anion exchange membranes by adjusting the functional group and side chain structure

Polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) has attracted more and more attention recently for using as the matrix of anion exchange membranes (AEMs) in fuel cells due to its low cost, superior mechanical properties and ether-free total C-C bond backbone. In this work, the short side chain of chloromethyl and long side chain of bromohexanoyl groups are grafted into the SEBS copolymer via the chloromethylation and Friedel-Crafts acylation reactions. After quaternized by different nitrogen heterocyclic compounds including 1-methylimidazole (Im), 1-methylpyrrolidine (Mpy), N-methylpiperidine (Pip) and 2-methyl-1-pyrroline (Mpyl), various SEBSCn-x AEMs are prepared. Combing with small molecule model experiment results, Mpy and Pip cations grafted SEBS membranes are confirmed to possess good alkali resistance, while SEBSC1-x membranes with Im and Mpyl cations are not suitable for AEMs due to their poor alkaline stability. Meanwhile, long side-chain cation grafted SEBSC6-x AEMs with lower ion exchange capacity (IEC) values exhibit higher water uptake, ionic conductivity and mechanical strength simultaneously comparing with short side-chain cation grafted SEBSC1-x AEMs. As an example, the SEBSC6-Pip membrane with an IEC of 0.48 mmol g−1 exhibits a water uptake of 47% at 80 °C, an OH− conductivity of 57.7 mS cm−1 at 80 °C, a tensile strength of 52 MPa at room temperature, and a conductivity retention percent of 75% after 600 h in 1 M KOH at 80 °C, demonstrating a big potential for the AEM fuel cell application.

Magnetorheological gel based on mineral oil and polystyrene-b-poly(ethene-co-butadiene)-b-polystyrene

Magnetorheological (MR) materials can have their properties reversibly altered by exposure to a magnetic field. Currently they can be divided into three categories: magnetorheological fluids (MRF), magnetorheological elastomer, and magnetorheological gel (MRG). MRFs present sedimentation problems inherent to the densities of their components. MRG are an alternative to MRF, but they still need to be further studied for their preparation. This study aims to prepare and evaluate the rheological behavior of eight MRG samples using iron carbonyl (HQ and OM) particles, SEBS copolymer and commercial mineral oil in different compositions. The samples were characterized by creep-recovery and angular frequency sweep, without magnetic field, and under magnetic fields of 88 and The sample OM4 ( OM, KRT and mineral oil) showed a viscosity increase around ten thousand times under favoring a wide range of control. Through the results, the study concludes that the magnetorheological response of MRG was more affected by the gelatinous matrix (OIL + SEBS) than the particle size used. Even so, there are indications that the interparticle separation distance (IPS) in the polymer matrix of the material also influences the behavior of the sample.

Synthesis of a proton exchange membrane from SEBS copolymer and natural latex modified with V2O5 for fuel cells

Synthesis of a proton exchange membrane from SEBS copolymer and natural latex modified with V2O5 for fuel cells

Low Frequency Relaxation in Block Copolymers and Nanocomposites

Results of the loss tangent, tan δ, at low frequencies, obtained for a SEBS copolymer and carbon nanotube (CNT)/polyurethane (PUR) nanocomposites, are analysed. The hindering effect of nanostructures (i.e. ordered domains or nanoparticles) on the motion of polymer chains is revealed by the occurrence of a mechanical relaxation at low frequencies. In the case of SEBS copolymer, the effect of domains orientation and extender oil on a characteristic time associated with the relaxation is investigated. For CNT/PUR nanocomposites, the variation of the frequency at which the relaxation takes place, with CNT concentration and temperature, reveals that the interactions between the nanotubes and the polymer chains are improved with temperature

A Study on Compatibility and Properties of POE/PS/SEBS Ternary Blends

Ethylene‐α‐olefin copolymer (POE)/polystyrene (PS)/poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) blends were prepared via melt blending in a co‐rotating twin‐screw extruder. The effects of SEBS copolymer on the morphology and rheological and mechanical properties of the blends were studied. Scanning electron microscopy (SEM) photos showed that the addition of SEBS copolymer resulted in finer dispersion of PS particles in the POE matrix and better interfacial adhesion between POE and PS compared with POE/PS blends, which exhibited a very coarse morphology due to the immiscibility between them. Interestingly, the tensile strength increased from 12.5 MPa for neat POE to 23.5 MPa for the POE/PS/SEBS (60/10/30) blend, whereas the tensile strengths of POE/PS (85.7/14.3) blend and POE/SEBS (66.7/33.3) blend were only 10.5 and 16.5 MPa, respectively. This indicates that both SEBS copolymer and PS have a synergistic reinforcing effect on POE. Dynamic mechanical thermal analysis (DMTA) and dynamic rheological property measurement also revealed that there existed some interactions between POE and SEBS as well as between SEBS and PS. DMTA results also showed that the storage modulus of POE increased when PS and SEBS were incorporated, especially at high temperature, which means that the service temperature of POE was improved.

Polypropylene/talc/SEBS (SEBS-g-MA) composites. Part 2. Mechanical properties

Isotactic polypropylene/styrenic rubber block copolymer blends (iPP/SRBC) as well as the iPP/talc/SRBC composites with 12 vol.% of aminosilane surface treated talc were studied by the measurement of mechanical properties (tensile properties and notched impact strength). Mechanical properties and their relation with the structure of polypropylene blends and composites were investigated as a function of poly(styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS) and the SEBS grafted with maleic anhydride (SEBS-g-MA) content in the range from 0 to 20 vol.% as elastomeric components. Elongation at yield of the iPP/talc/SEBS-g-MA composites and impact strength of the iPP/talc/SEBS composites show synergistic effect at high elastomer content (20 vol.%). Higher molecular weight (and consequently higher viscosity, elasticity and impact strength) of thicker SEBS layers around highly oriented talc crystals and higher miscibility or interactivity of SEBS than SEBS-g-MA with iPP chains seem to contribute to enormous impact strength of the iPP/talc/SEBS composites. On the other side, a higher extent of encapsulation and disorientation of talc crystals by the SEBS-g-MA than by SEBS copolymer, and lower molecular weight of the SEBS-g-MA than SEBS copolymer may contribute to higher elongation at yield of the iPP/talc/SEBS-g-MA composite.

Block copolymers as compatibilizers for blends of linear low density polyethylene and polystyrene

AbstractCompatibilization of blends of linear low‐density polyethylene (LLDPE) and polystyrene (PS) with block copolymers of styrene (S) and butadiene (B) or hydrogenated butadiene (EB) has been studied. The morphology of the LLDPE/PS (50/50) composition typically with 5% copolymer was characterized primarily by scanning electron microscopy (SEM). The SEB and SEBS copolymers were effective in reducing the PS domain size, while the SB and SBS copolymers were less effective. The noncrystalline copolymers lowered the tensile modulus of the blend by as much as 50%. Modulus calculations based on a coreshell model, with the rubbery copolymer coating the PS particle, predicted that 50% of the rubbery SEBS copolymer was located at the interface compared to only 5–15% of the SB and SBS copolymers. The modulus of blends compatibilized with crystalline, nonrubbery SEB and SEBS copolymers approached Hashin's upper modulus bound. An interconnected interface model was proposed in which the blocks selectively penetrated the LLDPE and PS phases to provide good adhesion and improved stress and strain transfer between the phases. © 1995 John Wiley & Sons, Inc.

Adhesion enhancement in polystyrene/polyethylene blends by corona treatment and triblock copolymer addition

A comparative study of interfacial effects due to styrene-butadiene-based triblock copolymer (SEBS) addition and to corona treatment has been investigated for blends of polyethylene (PE) and polystyrene (PS). Blends of PS/PE covering a wide range of weight composition have been prepared in the molten state. Scanning electron microscopy demonstrated that moderate amounts of SEBS copolymer addition (2-5%) resulted in finer particle dispersion and in better interfacial adhesion between PE and PS phases. Tensile strength and elongation at break were also significantly improved. In the case of corona treatment of both polyethylene and polystyrene, the tensile strength of the blends increased while their elongation at break remained almost unchanged. The same trend was found when small amounts of corona-treated blend (5%) were added to the non-modified PS/PE blends. Rheological measurements revealed that corona treatment resulted in a decrease of dynamic shear viscosity of both PE and PS. From a view-point of m...

Deformation behavior of HDPE/(PEC/PS)/SEBS blends

AbstractImmiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC) were compatibilized with various amounts of a styrene‐hydrogenated butadiene block copolymer (SEBS). PEC is structurally similar to poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO). Using a liquid displacement stress dilatometer, the volume change of samples during uniaxial mechanical straining was determined and related to the various modes of deformation. Blends were fabricated by both injection and compression molding. Miscible PEC and PS blends were found to undergo a craze to shear yielding transition between 40 and 60% PS, which occurred at higher PS concentrations as SEBS was added. Blends with a HDPE matrix and a dispersed glassy phase showed reduced volume dilatation on adding SEBS, indicating better interfacial adhesion between the incompatible blend components. Increases in the sample volume were substantially less in blends with a PEC/PS glassy phase instead of pure PS, suggesting more effective compatibilization by the SEBS copolymer in blends with PEC. This trend is presumed to stem from an exothermic heat of mixing between the PS endblocks of SEBS and the PEC‐rich phases in the blend. Microscopic evidence of the improved adhesion and modes of deformation agrees with the results obtained by dilatometry. The volume dilatation of compression‐molded materials do not seem to be similarly affected by the composition of the glassy phase which may reflect morphological differences between injection‐and compression‐molded blends.