Styrene-butadiene

About: Styrene-butadiene is a research topic. Over the lifetime, 5568 publications have been published within this topic receiving 62099 citations. The topic is also known as: styrene-butadiene rubber & SBR.

Experimental Fracture Toughness Study for some Modified Asphalt Mixtures

Abstract: The use of modifiers or additives in the asphalt mixtures is a suitable and common method for improving their mechanical properties especially under high temperature service conditions. However, for cold climates which the pavement of roads usually experience subzero temperatures, the overall failure mechanism of asphalt layers may be occurred mainly due to elastic brittle fracture and growth of initiated cracks inside the pavements. Fracture toughness is the most important parameter for characterizing the crack growth and failure of cracked materials and structures such as the asphalt pavements. Hence, the main aim of this research is to study the effect of different additives including Poly phosphoric acid (PPA), Styrene butadiene styrene (SBS), Anti striping agent (ANTI), Crumb rubber (CR) and FT-paraffin wax (Sasobit) on the low temperature mode I fracture resistance of asphalt mixtures. A series of asphalt samples with different percentages of the mentioned additives were manufactured in the shape of semi circular specimens containing vertical edge cracks. The test samples were then loaded monotonically using a symmetric three-point bend fixture at a constant subzero temperature of-15°C. The value of mode I fracture toughness (KIc) were determined by recording the critical fracture loads of tested specimens. It is shown that all the investigated additives increase the low temperature fracture toughness of the asphalt mixture and the maximum increase in the value of KIc occurs when the sasobit and CR additives are used.

Structure and properties of a styrene–butadiene–styrene block copolymer

Abstract: Electron-microscopic texture and physical properties of a styrene–butadiene–styrene (SBS) block copolymer obtained by casting from toluene, carbon tetrachloride, ethyl acetate, and methyl ethyl ketone are discussed. Two peaks are observed in the mechanical loss (tan delta;) curve at −70 and 100°C which are attributed to segmental motion of polybutadiene and polystyrene, respectively. The polybutadiene peak heights are in the order of solubility in the solvent used; the polystyrene peak heights are in converse order. In addition to these peaks, a third peak is observed at 10°C for specimens cast from ethyl acetate or methyl ethyl ketone. A transition corresponding to this peak is also noticed in thermal analysis. It is proposed that aggregation of styrene blocks is relatively incomplete in specimens cast from solution in poor solvents.

Physico-mechanical properties and thermal stability of thermoset nanocomposites based on styrene-butadiene rubber/phenolic resin blend

Abstract: Effect of organoclay (OC) on the performance of styrene-butadiene rubber (SBR)/phenolic resin (PH) blend prepared by two-roll mill was investigated. The influence of OC content ranging between 2.5 and 30 phr on the performance of SBR/PH was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), interfacial energy analysis, tensile, dynamic mechanical, swelling, cure rheometry and thermogravimetric analysis (TGA). It was found that the OC is mainly localized in the SBR phase of SBR/PH blend through the kinetically favored mechanism relevant to rubber chains. The results also demonstrated the positive role of PH on the dispersion of OC. Both PH and OC showed accelerating role on the cure rate of SBR and increased the crosslinking density of the rubber phase. Additionally, the mechanical and dynamic mechanical properties of SBR were influenced by incorporation of both PH and OC. TGA showed that the OC improves thermal stability of SBR vulcanizate, while it exhibits a catalytic role in presence of PH.

Evaluation of the properties of bitumen modified by SBS copolymers with different styrene–butadiene structure

Abstract: Four styrene–butadiene–styrene(SBS) modified bitumens had been prepared by a base bitumen, a crosslinking agent and four SBS copolymers which differ in styrene blocks content and molecular configuration (radial or linear) under the same experimental conditions. Conventional properties, morphology, thermal behavior and microstructure were investigated by means of conventional tests, fluorescence microscopy, differential scanning calorimetry (DSC), and Fourier transform infrared (FT-IR) spectroscopy. In terms of linear SBS polymers, the SBS molecule with the styrene content of 30% has a perfect dispersion and complete stretching in bitumen matrix, and in this case, the conventional properties and thermal stability of bitumen are enhanced substantially. However, the star SBS polymer due to long branched chains forming the preferable steric hindrance to enhance the intensity of base bitumen, plays a more important role in improving the conventional properties of base bitumen than linear SBS polymers. Furthermore, the FT-IR spectra indicate that, the main bands assignations of four modified bitumens are identical and the significant variation is the peak intensity. And a noncomplete crosslinking reaction happens between the bitumen and each SBS polymer, which can efficiently prevent excessive cross-linking from affecting the intrinsic bitumen characteristics. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40398.