Polymer SEBS

Rubber-like materials now superseding the traditional mastics and putties used in the building industry. Such sealants (also termed mastics) are based on butyl rubber, liquid polysulphides, silicone rubbers, polybutylene, nitrile rubbers and plasticised vinyl polymers. SEBS... 

Recently, Liu et al. [34] prepared banana fibre (BaF)-filled composites based on high-density polyethylene (HDPE)/polyaminde-6 (PA 6) blends via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystaUization/melting, thermal stability, water absorption and... 

FIGURE 2.15 Forces of interactions on blocks and nanoclay of poly[styrene-(ethylene-co-butylene)-styrene] (SEBS)-clay nanocomposite taken from force-volume experiments. (From Ganguly, A., Sarkar, M.D., and Bhowmick, A.K., J. Polym. Set, Part B Polym. Phys., 45, 52, 2006. Courtesy of Wiley InterScience.)... 

The authors are thankful to Dr. P. Sadhukhan (Bridgestone/Firestone Research, Akron, OH) for different rubber samples Dr. T. Medintseva (the Semenov s Instimte of Chemical Physics, Moscow, Russia) for TPV samples Dr. N. Dutta (University of South Australia, Adelaide, Australia) for the samples of SEBS filled with oil Dr. Z. Petrovich (Kansas Polymer Research Center, Pittsburg State University, Pittsburg, KA) for PU samples, and NIST/ATP Award 70NANB4H3055 for financial support. 

Hong, B. K. and Jo, W. H. (2000) Effects of molecular weight of SEBS triblock copolymer on the morphology, impact strength, and rheological property of syndiotactic polystyrene/ ethylene-propylene rubber blends. Polymer, 41, 2069-2079. 

Usually polymeric substances of appropriate chemical structure and morphology which promote the miscibility of incompatible materials. Block copolymers are especially useful surfactants at the polymer/polymer interface because the two blocks can be made up from molecules of the individual polymers to be mixed. Typical compatibilisers in polymer blends are LDPE-g-PS in PE/PS CPE in PE/PVC acrylic- -PE, -PP, -EPDM in polyolefin/PA and maleic-g-PE, -PP, -EPDM, -SEBS in polyolefin/polyesters. 

The effects of equivalent weight (FW = g polymer/mol SO3H) and water content on diffusion coefficient, solubility, and permeability of oxygen for fully hydrated BAM, S-SEBS, ETFE- -PSSA, Nafion 117, and BPSH membranes have been studied. It has been found that the diffusion coefficients of all the studied membranes decrease with increasing EW, while the solubility correspondingly increases. These trends are the same as found in... 

For ETFE- -PSSA membranes with the same lEC, water uptake is higher than MeOH uptake of the membrane, but for Nation and S-SEBS membranes, MeOH uptake of membrane is always higher than water uptake. Chemical structure and morphology of membranes affect the solvent absorption. Nafion is considered to consist of ionic clusters that are separated from the polymer phase. For grafted polymers, heterogeneity exists to some extent due to the hydrophobic base polymer however, a regular clustered structure, as in the case of Nafion, has not been proposed for these materials. 

Edmondson, C. A., Eontanella, J. J., Chung, S. H., Greenbaum, S. G. and Wnek, G. E. 2001. Complex impedance studies of S-SEBS block polymer proton-conducting membranes. Electrochimica Acta 46 1623-1628. 

As more complex multicomponent blends are being developed for commercial applications, new approaches are needed for morphology characterization. Often, the use of Ru04 staining is effective, as it is sensitive to small variations in the chemical composition of the component polymers. For instance PS, PC, and styrene—ethylene/butylene—styrene block copolymers (SEBS) are readily stained, SAN is stained to a lesser degree, and PBT and nylons are not stained (158,225—228). 

Sulfonation is very useful chemical modification of polymer, as it induces high polarity in the polymer changing its chemical as well as physical properties. Sulfonated polymers are also important precursors for ionomer formation [75]. There are reports of sulfonation of ethylene-propylene diene terpolymer (EPDM) [76, 77], polyarylene-ether-sulfone [78], polyaromatic ether ketone [79], polyether ether ketone (PEEK) [80], styrene-ethylene-butylene-styrene block copolymer, (SEBS) [81]. Poly [bis(3-methyl phenoxy) phosphozene] [82], Sulfonated polymers show a distinct peak at 1176 cm"1 due to stretching vibration of 0=S=0 in the -S03H group. Another peak appears at 881 cm 1 due to stretching vibration of S-OH bond. However, the position of different vibrational bands due to sulfonation depends on the nature of the cations as well as types of solvents [75, 76]. 

SEBS Styrene-ethylene-butylene-styrene block co-polymer... 

The butadiene blocks can be hydrogenated, as mentioned above with hydrogenated nitrile, to form SEBS polymers having better thermal stability and chemical resistance. The EB stands for ethylene-butylene, which are the structures formed after the butadiene segments have been hydrogenated. 

Figure 21.8 Endblock size effect on softening point of various SEBS block copolymers by L. K. Djiauw, Kraton Polymers LLC (internal communication), Westhollow Technology Center, Houston, TX (1999)...

Strength generally increases as the driving force for phase separation between the blocks, %N, increases in the order SIS < SBS << SEPS, SEBS, where N is the polymer molecular weight and x is the segmental interaction parameter. 

Figure 21.12 TEM of an SEBS polymer dispersed in a matrix of polycarbonate. The styrene domains and the polycarbonate matrix are stained dark with R11O4, making the rubber appear light...

Hydrogenated SBCs are often used to modify polyolefins such as polypropylene, polybutylene and polyethylene. One of the unique characteristics of strongly phase-separated block copolymers such as high molecular weight (>50 000) SEBS and SEPS is their response to shear in the melt. These polymers retain their phase-separated structure well above the Tg of the polystyrene because their order-disorder transition temperatures are above processing temperatures. This phase separation strongly inhibits flow in the absence of shear resulting in infinite viscosity at zero shear rates. The application of shear... 

Linear low-density polyethylene (LLDPE) and PS resins were the same as described previously (Chapter 21). The various block copolymers that were used as compatibilizers have also been described (I). A series of crystalline copolymers (Q series) was prepared by hydrogenation of diblock and triblock copolymers of styrene and butadiene [styrene-hydrogenated butadiene (SEB) and styrene-hydrogenated butadiene—styrene (SEBS)J (1). Triblock copolymers of styrene and butadiene [styrene-butadiene-styrene (SBS)] and a noncrystalline hydrogenated block copolymer (SEBS) (Kraton) were supplied by Shell Chemical Co. Diblock copolymers of styrene and butadiene [styrene-butadiene (SB) (Vector)] were obtained from Dexco Polymers. The characteristics of the resins are given in Table I. 

CL has been employed to study the mechanism of degradation in polymers such as UV-cured aliphatic polyurethane-acrylate-based adhesives. In styrenic block copolymers, SEBS, the order of the reaction was determined, and the efficiency of antioxidants was evaluated. Also, the relationship between thermooxidation of SEBS and morphology was established, indicating that for these copolymers the oxidation started in the interfacial region. 

C-Flec . [Concept Polymer] Thermoplastic elastomers inch SEBS, SBS for medical, laboratory, food, and industrial fields. 

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