SEBS

Most elastomers that are used for nylon modification contain a small amount of maleic anhydride (0.3 to 2%). In the melt blending process, these elastomers react with the primary amine end groups in nylon, giving rise to nylon grafted elastomers. These grafts reduce the interfacial tension between the phases and provide steric stabili2ation for the dispersed mbber phase. Typically, thermally stable, saturated mbbers such as EPR, EPDM, and styrene—ethylene/butylene—styrene (SEBS) are used. 

Seb cic Acid. Sebacic acid [111-20-6] C QH gO, is an important intermediate in the manufacture of polyamide resins (see Polyamides). It has an estimated demand worldwide of approximately 20,000 t/yr. The alkaline hydrolysis of castor oil (qv), which historically has shown some wide fluctuations in price, is the conventional method of preparation. Because of these price fluctuations, there have been years of considerable interest in an electrochemical route to sebacic acid based on adipic acid [124-04-9] (qv) as the starting material. The electrochemical step involves the Kolbn-type or Brown-Walker reaction where anodic coupling of the monomethyl ester of adipic acid forms dimethyl sebacate [106-79-6]. The three steps in the reaction sequence from adipic acid to sebacic acid are as follows ... 

The hydrogenated materials have a higher maximum service temperature than the conventional SBS materials and, because of the absence of double bonds in the chain, better weathering properties. Known as SEBs these materials now find use in adhesives, sealants and roofing membrane compounds. These also find use in highly filled automotive acoustic barriers and in medical, sports and leisure applications. 

Styrene-butadiene-styrene triblocks and the related S-I-S and SEBS materials (Section 11.8). 

Fig. 5. Representative block copolymer structures, (a) Routes to SIS i, coupling reaction ii, sequential, (b) Three and four-arm SI stars, (c) (Sllih radial, (d) (SEB)2B2 radial.

SBS and SIS can be subsequently hydrogenated to form SEBS and SEPS, respectively. SEBS is obtained from SBS with a higher vinyl content (typically around 30%) in order to avoid crystallization of the mid-block. The properties of all four of these common styrenic block copolymers are displayed in Table 2. 

Anionic Styrenic block copolymers (SBS, SIS, SEBS, SEES) 1.0-1.1 Excellent... 

Because of concerns about long term stability and transfer resistance, adhesives based on saturated SBCs, primarily SEBS, have dominated this application. Over time, cost pressures have encouraged the use of unsaturated rubbers, both SIS and... 

Impact strength toughness PVC, PP, PE ABS, ASA, SEBS, Block copolymer, SEBS, EPR, EPDM,... 

Figure 2 Notched Izod impact strength of ternary PA-PP-SEBS-g-MAH blends with 0 wt%, 5 wt%, and 10 wt% SEBS-g-MAH. Source Ref. 44.

The influence of maleic anhydride modified styrene-(ethylene-co-butylene)-styrene (SEBS) triblock copolymer as a reactive compatibilizer in a nylon-6-SEBS blend was investigated by Wu et al. [66]. When the ma]e-ated SEBS was incorporated into the PA-6-SEBS biend. 

Table 3 The Formulation and the Impact Strength of the PA-6-SEBS-g-MA Blends...

PA6 (wt%) Recipe SEES (wt%) MA-g-SEBS (wt%) MA graft ratio (gMA/gSEBS) Impact strength (J/m)... 

SEBS-g-MA - maleic anhydride grafted styrene (ethyl-... 

When ACPC was condensed with hexamethylene diamine in the presence of two other acid chlorides (seb-acoyl or adipoyl chloride), poly(amide)s 6.6 and 6.10 with various numbers of azo groups per repeating unit (between 0.14 and 1.0, depending on the ratio of the acid chlorides used) could be obtained [35,36]. Thus, block copolymers with a controlled segment length of the poly-(amide) blocks were attainable. 

J mol ). This is additional evidence in favor of rate limitation by inner diffusion. However, the same reaction in the presence of Dowex-50, which has a more open three-dimensional network, gave an activation energy of 44800 J mol , and closely similar values were obtained for the hydrolysis of ethyl acetate [29] and dimethyl seb-acate [30]. The activation energy for the hydrolysis of ethyl acetate on a macroreticular sulphonated cationic exchanger [93] is 3566 J mol . For the hydrolysis of ethyl formate in a binary system, the isocomposition activation energy (Ec) [28,92] tends to decrease as the solvent content increases, while for solutions of the same dielectric constant, the iso-dielectric activation energy (Ed) increases as the dielectric constant of the solvent increases (Table 6). 

If high impact resistance is required, the PA can be modified with rubber particles.11,15 The blends are usually made by reactive compounding from maleic-anhydride-modified rubbers, such as, EPDM, EPR, polybutadiene, or SEBS. Partial amorphous PA with a high Tg combines to give a high dimensional stability and good solvent resistance with transparency. 

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.)... 

Saturated styrene-ethylene-butylene-styrene (SEBS) and styrene-ethyl-propyl-styrene (SEPS) are produced by hydrogenating SBS and SIS block copolymers, respectively, before they are recovered from the solution [3]. 

Lindsey C.R., Paul D.R., and Barlow J.W., Mechanical properties of HDPE-PS-SEBS blends, J. Appl. 

ABS or ASA (acrylonitrile-styrene-acrylate) Carboxylated polyolefin elastomer (SEBS-MA)... 

EPDM-g-glycidyl methacrylate SEBS block copolymer polypropylene... 

Polycarbonate-polystyrene blend along with poly(alkylene-dicarboxylate) such as SMA SEBS copolymer for toughening blends of PPO with nylon and polyolefin (proprietary compatibilizer)... 

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. 

Elnancdal si jport of this work throu the Deutsche Rorschungsgemein-schaft (SEB 6 and 128) is gratefully acknowledged. 

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