Styrene-butadiene Block Copolymers Research Articles

Morphology, chemical reaction mechanism, and cross-linking degree of asphalt binder modified by SBS block co-polymer

Recently, the batch production of styrene–butadienestyrene (SBS) modified asphalt has been realized, but quality control is still in the empirical stage. While the chemical reaction position and the cross-linking degree are unclear, affecting the controlling quality of SBS modified asphalt. Therefore, this study investigated the influence of the reaction conditions and the stabilizer content on the performance and morphology of the SBS modified asphalt. And whether the chemical reaction exists and the chemical reaction position were confirmed by preparing the polystyrene (PS) monomer, polybutadiene(PB) monomer, and SBS modified asphalt with and without stabilizer. Finally, the fluorescence microscope (FM) test, Fourier transformation infrared spectroscopy (FTIR) test and the chemical titration method were used to characterize quantitatively the microstructure changes of SBS modified asphalt. The results show that the reaction conditions greatly influence the performance of SBS modified asphalt. After adding the stabilizer, the phase state of the system changed from the SBS phase as a dispersed phase and the asphalt phase as a continuous phase to the double continuous phase, and the network structure was formed. The chemical reaction has taken place in the PB and SBS modified asphalt, and the PB segment of the SBS polymer participates in the chemical reaction. Furthermore, the degree of cross-linking reaction of SBS modified asphalt is low, and the range of the cross-linking percentage is about 12.3%-14.5%.

MXene by regulating etching conditions enhanced UV resistance of SBS modified asphalt: Evaluating asphalt photo-oxidation and SBS degradation

The pursuit of improving the special properties of modified asphalt using advanced nanomaterials and understanding its mechanism based on material properties is highly attractive topic. In this study, four types of MXene (Ti3C2Tx) (prepared by adjusting the synthesis methods) were incorporated into styrene–butadienestyrene (SBS) block copolymer modified asphalt as ultraviolet (UV) aging resistant modifiers. The UV aging behaviors, such as asphalt photo-oxidation and SBS copolymer degradation, were evaluated by simulating UV aging of modified asphalts using indoor equipment. The chemical and rheological results showed that MXene incorporated modified asphalts had excellent high-temperature performance and rutting resistance. Furthermore, MXene incorporation significantly inhibited asphalt oxidation and SBS copolymer degradation. The underlying mechanism of these intriguing properties was found to be the few-layered structure and -F, -O surface end groups of MXene, which were the key factors responsible for the enhanced anti-UV aging performance of modified asphalt.

The Cellular Structure and Toughness of Hydrogenated Styrene-Butadiene Block Copolymer Reinforced Polypropylene Foams

Polypropylene nanocomposites containing varying amounts of Styrene-ethylene-butadiene-styrene block copolymer (SEBS) were prepared through the supercritical nitrogen microcellular injection-molding process. Maleic anhydride (MAH)-grafted polypropylene (PP-g-MAH) copolymers were used as compatibilizers. The influence of SEBS content on the cell structure and toughness of the SEBS/PP composites was investigated. Upon the addition of SEBS, the differential scanning calorimeter tests revealed that the grain size of the composites decreased, and their toughness increased. The results of the rheological behavior tests showed that the melt viscosity of the composite increased, playing a role in enhancing the cell structure. With the addition of 20 wt% SEBS, the cell diameter decreased from 157 to 66.7 μm, leading to an improvement in the mechanical properties. Compared to pure PP material, the impact toughness of the composites rose by 410% with 20 wt% of SEBS. Microstructure images of the impact section displayed evident plastic deformation, effectively absorbing energy and improving the material's toughness. Furthermore, the composites exhibited a significant increase in toughness in the tensile test, with the foamed material's elongation at break being 960% higher than that of pure PP foamed material when the SEBS content was 20%.

Study on materials composition and process parameters of polyurethane-modified asphalt synthesized in-situ by the one-shot process

To improve the performance of ordinary road asphalt, and overcome the problems of poor thermal storage stability, easy segregation, and high preparation temperature of polymer-modified asphalt such as SBS (styrene–butadienestyrene block copolymer) or rubber powder. Polyurethane-modified asphalt (PUMA) was synthesized in-situ by the one-shot process with varying dosages of polyurethane (PU) raw materials (2.86 wt% ∼ 11.94 wt%) and isocyanate index R (–NCO/–OH) values (2, 3, 5, and 7) for a total of 12 samples, in this study. The material composition, development time, and modification mechanism of PUMA were analyzed using the approach of “macro performance + micro mechanism”. Firstly, the conventional properties, rotational viscosity, and rheological properties of PUMA samples were evaluated and compared to virgin asphalt. Secondly, under the optimal material composition scheme, the conventional performance and thermal storage stability differences between MOCA (3, 3′ -dichloro-4,4′ -diamino diphenyl methane) and BDO (1,4-butanediol) were compared. Comparing the performance of PUMA during the development times of 0 to 12 h, the oven temperature is 105 °C. Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM) were used to analyze the chemical structure and spatial structure of PU in asphalt. The results indicate that: 1) the higher the R (–NCO/–OH), the higher the asphalt's high-temperature performance, elastic recovery performance, and viscosity, but the lower its low-temperature performance. 2) Under the same R (–NCO/–OH) condition, the increase in PU has little effect on the preceding performance. 3) MOCA is marginally superior to BDO in terms of high-temperature performance, whereas BDO has greater advantages in terms of low-temperature performance; compatibility is comparable. 4) At 105 °C, the performance continued to improve for 0 to 5 h, but after 5 to 12 h, the improvement was no longer noticeable. 5) Due to the reaction of the isocyanate group with the polyol and the active group in the asphalt, functional groups such as carbamate and urea are directly synthesized in the asphalt, allowing the PU molecular chain to expand and form a network structure within the asphalt. This procedure modifies the performance of the virgin asphalt. These findings not only improve our understanding of the effect of optimal material composition and development time on the properties of PUMA, but they also provide direction for future research.

Research on the synergistic modification effect and the interface mechanism of GO/SBS compound-modified asphalt based on experiments and molecular simulations

Although there have been reports showing the modification effect of carbon nanomaterials on asphalt, there are few studies on whether carbon nanomaterials and polymers can have synergistic modification effects on asphalt. At the same time, the complex composition of asphalt makes it difficult to determine the interface mechanism between the modifier and the asphalt. In this study, graphene oxide (GO) and styrene–butadiene–styrene block copolymer (SBS) were selected as modifiers. A combined experimental and molecular simulation research method was used to study the synergistic modification effect and the interface mechanism between the modifier and the asphalt. The results show that the modification effect of GO/SBS incorporated into asphalt is significantly superior to that of GO or SBS incorporated individually and GO/SBS has a synergistic modification effect. Although the binding strength between SBS and asphalt is weak, the GO surface (GO (0 0 1)) can simultaneously bind with SBS and asphalt, increasing the binding strength of SBS and asphalt as well as promoting the dispersion of SBS in asphalt, so that GO/SBS shows a synergistic modification effect and improves properties such as low-temperature ductility, rheology and storage stability at macroscopic level. Intercalated and exfoliated structure can be formed between GO side (GO (0 1 0)) and asphalt, which improves the anti-aging properties of the asphalt. Physical bonding is the main interface binding for GO/SBS compound-modified asphalt. GO bonds to asphalt or SBS by hydrogen bonds and there are only dispersion forces between SBS and asphalt, resulting in a higher binding strength between GO and asphalt or SBS than between SBS and asphalt.

Research on creep and thermal stability of asphalt under outdoor aging (NEA) in Tibetan areas

In order to explore the aging performance attenuation mechanism of 90# and SBS (styrene–butadiene–styrene block copolymer) modified asphalt under the large temperature difference and strong ultraviolet radiation in the Tibetan area, this paper adopts the outdoor natural exposure aging (NEA) condition in the Tibetan area. Scanning calorimetry and thermogravimetric analysis techniques were used to test and analyse the permanent deformation resistance and thermal stability of two asphalts with different aging times (0 month (0M), April (4M) and 8 months (8M)) to study the on-site aging mechanism of asphalt in Tibetan areas. The results show that with the prolongation of NEA time, the non-recoverable creep compliance, polymer area and glass transition temperature of the two asphalts decrease, while the average recovery rate and deformation temperature increase, and the aging degree gradually deepens. Under the special outdoor conditions in Tibetan areas, the permanent deformation resistance and thermal stability of SBS modified asphalt are better than 90# asphalt. The research results explored the aging and decay mechanism of the two asphalts from the macro and micro perspectives, which provided theoretical support for the research and development of anti-aging technology in Tibetan areas and guaranteeing the road performance of asphalt pavement in the whole life cycle.

Application of infrared spectroscopy in combination with chemometric algorithms for determining the presence of styrene-butadiene block copolymer in bitumen products

At present polymer-bitumen binders (PBB), including those containing styrene-butadiene copolymer (SBC), are widely used for improving the performance of asphalt concrete coverings. Qualitative detection of the polymer in the petroleum bitumen composition is a difficult research task owing to the low content of the polymer in the PBB composition. Existing methods for determining the polymer in petroleum bitumen are based on a complex multi-stage extraction or on measuring the specific characteristic viscosity of the polymer in the analyzed PBB. These methods are time-consuming and labor-intensive, and require application of a number of specific organic solvents and reference standards. The present work considers the possibility of applying infrared spectroscopy of disturbed total internal reflection (ATR) with subsequent processing of spectra using chemometric algorithms in the study of PBB containing SBC. Application of the principal component analysis (PCA), as well as one-class classification method, the method of soft independent modeling of class analogy (DD-SIMCA), is illustrated. The use of infrared spectroscopy in combination with chemometric data processing methods greatly simplifies and accelerates the research task of detection SBS in bitumen products. The objective of this work was to solve the classification and identification problem in the course of studying bitumen products, i.e. attributing/non-attributing a bitumen product to PBB with SBS.

Effect of PAN fiber with bionic layered surface structure generated in situ by Fenton reaction on performance of SBS/RP asphalt binder

• Innovative application of Fenton reaction in the modification of polyacrylonitrile fibers. • Biomimetic multi-layered structure modified polyacrylonitrile fibers. • KF-PAN/SBS/RP modified asphalt had better viscoelastic performance. • KF-PAN/SBS/RP modified asphalt had better low temperature anti-cracking performance, high temperature stability and fatigue damage resistance. • KF-PAN/SBS/RP modified asphalt had better rutting resistance and high temperature adhesion performance. In this study, a surface modified polyacrylonitrile fiber (KF-PAN) with a fish-scale whisker-like biomimetic hierarchical structure was successfully prepared via in situ competition effect of Fenton reaction. The modified fibers were used as secondary modifiers to prepare fiber-reinforced styrene–butadienestyrene (SBS) block copolymers and rubber powder (RP) modified asphalt binders (KF-PAN/SBS/RP). Energy dispersive spectroscopy, scanning electron microscopy, and atomic force microscopy analyses revealed the successful construction of bionic hierarchy on the fiber surface, and confirmed rough surface of the KF-PAN fibers. The hierarchical structure of the fiber surface acted as a buffer in the asphalt and strengthened the mutual interaction of the fiber and asphalt. Dynamic rheometer shear and strip-tensile tests showed that the KF-PAN/SBS/RP modified asphalt exhibited better viscoelasticity, rutting resistance, and tensile properties than the PAN/SBS/RP modified asphalt. The linear amplitude sweep test showed that KF-PAN/SBS/RP modified asphalt had better fatigue resistance. Thermogravimetric analysis tests indicated that the surface bionic structure of KF-PAN fibers boosted thermal stability of the fibers, which in turn enhanced the thermal stability of KF-PAN/SBS/RP modified asphalt. Fluorescence microscopy analysis showed that incorporating KF-PAN fibers improved the SBS and RP microstructure inside the asphalt, forming a good mesh structure, and alleviating the stress concentration phenomenon in SBS/RP asphalt under external traffic load.

Aging Simulation of SBS Modifier during Service Life of Modified Asphalt

Research on the aging process of styrene-butadiene-styrene block copolymers (SBS) block copolymers modifier has practical significance in guiding the recycling of SBS-modified asphalt pavement. The objective of this study is to investigate the aging process of SBS modifier under various oxygen and thermal conditions to address the variations of physical properties and chemical reaction during the service life of recycled asphalt pavement (RAP). In the proposed testing process, SBS modifier was thermal oxidative and vacuum thermal aged at different temperatures and time prior to blending with base asphalt to prepare SBS-modified asphalt. SBS modifier was first dissolved by carbon tetrachloride (CCl4) and then tested through infrared (IR), gel permeation chromatography (GPC), and thermogravimetric (TGA) tests to investigate the variations on microstructure and chemical compositions of aged SBS modifier. The effect of aged SBS modifier on performance of SBS-modified asphalt was evaluated by comparing the mechanical and chemical properties of base and SBS-modified asphalts. Based on the results of the experimental program, appearance variation, modifying effects, and chemical reaction of SBS modifier under oxygen condition were obviously different from that of vacuum condition. The chemical reaction of SBS modifier was not significant at vacuum and high temperature condition, instead, a small amount of degradation was observed. Degradation of mechanical performance of SBS-modified asphalt was mainly caused by aging of base asphalt. Therefore, the SBS modifier in the RAP was suggested to be considered in the mixture design.

Research on preparation and properties of pH responsive superhydrophobic coating modified by SEBS

Smart materials with reversible wettability have attracted a lot of attention for application in sewage treatment. In this work, a pH-responsive polymer was prepared via the one-step free radical polymerization of 3-(trimethoxysilyl) acrylate and 2-dimethylaminoethyl methacrylate. The obtained pH-responsive polymer was then coated with a hydrogenated styrene–ethylene–butadiene–styrene block copolymer to endow the material with pH-responsive switchable superhydrophilic and superhydrophobic properties. Due to the excellent self-cleaning and mechanical stability of the coating, it was used to modify paper, which was then successfully utilized in the treatment of oily wastewater, showing great potential for use in advanced applications.

Preparation and properties of a novel high-viscosity modified bitumen

To develop a high-performance binder for open-graded porous asphalt mixtures, a novel high-viscosity modified bitumen (N-HVA) was prepared by melt blending base bitumen, terpene-styrene resin (TSR), styrene–butadienestyrene block copolymer (SBS), compatibilizer, and stabilizer, the optimal dosage of each modifier was determined. Properties and microstructure of the N-HVA were explored. Two commercially high-viscosity modified bitumens, TPS-HVA and SINOTPS-HVA, were adopted for comparison. The test results show that the appropriate dosage of modifiers is 7 wt% SBS, 4 wt% TSR, 3 wt% compatibilizer, and 0.2 wt% stabilizer. N-HVA shows improved rutting resistance, anti-aging ability, low-temperature flexibility, and meets the storage stability requirements. It demonstrated a more balanced performance than SINOTPS-HVA and TPS-HVA. During the preparation of N-HVA, the addition of the modifier inhibits the phase transition of the bitumen and raises the thermal stability of the composite system. In addition, the composite modifier possesses excellent compatibility with the base bitumen. The modification process is mainly based on physical blending, accompanied by chemical reactions..

Investigation of using conductive asphalt concrete with carbon fiber additives in intelligent anti-icing systems

ABSTRACT In winter, ice on the roads causes traffic accidents and congestion. In recent years, various techniques have been developed to provide more effective, efficient, and environmentally friendly solutions to the problem of road icing. One of these is electrically conductive asphalt concrete (CAC). This study aims to develop an intelligent anti-icing system by increasing the conductivity and mechanical properties of asphalt concrete. Two different conductive asphalt series were produced. Series 1 uses a binder modified with 3% styrene butadiene styrene (SBS) block copolymer and Series 2 uses a binder modified with both 3% SBS and 14% carbon black (CB). In both series, 0.3% carbon fiber (CF) by weight was added to the dry mixture. Thermal dissipation status, ice melting performance, freezing, and electrical conductivity heating cycle tests were conducted. The long-term mechanical and conductivity performances of CAC specimens were assessed with pre-and post-cycle experiments. CAC, developed for its conductivity and mechanical properties, was integrated with the intelligent anti-icing system. A comparative cost analysis was also performed to assess conventional asphalt concrete and the CAC. The binder phase was found to contribute to the mixture conductivity. Such systems can be integrated with Intelligent Transportation Systems (ITS).

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

Visualization of Macrophase Separation and Transformation in Immiscible Polymer Blends

A Morphological Study of Dynamically Vulcanized Styrene-Ethylene-Butylene-Styrene/Styrene-Butylene-Styrene/MethylVinylSilicon Rubber Thermoplastic Elastomer.

In this work, we prepared thermoplastic silicone rubber (TPSiV) by dynamically vulcanizing different relative proportions of methyl vinyl silicone rubber (MVSR), styrene ethylene butene styrene block copolymer (SEBS), and styrene butadiene styrene block copolymer (SBS). The compatibility and distribution of the MVSR phase and SEBS/SBS phase were qualitatively characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) tests on TPSiV. Subsequently, the backscattered electron signal image was analyzed using a colorimeter, and it was found that the size of the interface layer between the MVSR phase and the SEBS-SBS phase could be quantitatively characterized. This method overcomes the defect of the etching method, which cannot quantitatively analyze the size of the compatible layer between the two polymers. The final experiment proved that the two phases in TPSiV exhibited a “sea-island” structure, in which the MVSR phase acted as a dispersed phase in the SEBS-SBS phase. In addition, the addition of the silane coupling agent KH-907 (γ-isocyanatopropyltriethoxysilane) improved the mechanical properties of TPSiV, increasing the tensile strength by about 40% and the elongation at break by 30%. The permanent tensile deformation increase rate was about 15%. Through the quantitative measurement of the compatible layer, it was found that KH-907 could increase the thickness of the interface layer between the MVSR phase and the SEBS-SBS phase by more than 30%, which explained why the silane coupling agent KH-907 improved the mechanical properties of TPSiV at the micro level.

Study on macroscopic properties and microstructure of thermosetting polyurethane asphalt binder (PAB) based on curing kinetics

Recently, novel thermosetting polyurethane asphalt binder (PAB) has been studied by more researchers. This paper investigated the curing mechanism, microstructure and macroscopic performance of PAB. The mechanical properties, rheological properties, and elastic recovery performance of PAB were evaluated. Fourier transform infrared spectroscopy (FTIR), fluorescence microscopy (FM) and gel permeation chromatography (GPC) were adopted to confirm the chemical reaction and microstructure, curing process was studied combined with kinetics. Results showed PAB was the first-order curing reaction system and slow curing progress was conducive to mixing application, polyurethane particles changed from granular to the reticular structure during curing. The ratio of large molecular weight showed an increasing trend as temperature/time up. Furthermore, multi-stress creep recovery demonstrated that elastic recovery performance of PAB-50 (0.1 kPa) can be improved to 2.2 times, 8.1 times approximately compared with styrene–butadienestyrene block copolymer asphalt binder (SBSMA) and unmodified asphalt binder (MA). The tensile strength of PAB-30 (cured at 4d-130 °C) was 3.1 times that of 2 h (130 °C). Viscosity temperature index (VTS) value gradually increased implied that temperature sensitivity was habited by curing time. Pearson correlation coefficient illustrated that the mechanical property of PAB was positively related to the large molecular weight and conversion rate of the isocyanate group. The non-recoverable creep compliance reduction positively relied on polyurethane content and microstructure.

Styrene‐butadiene‐styrene‐based shape memory polymers: Evolution and the current state of art

AbstractStyrene butadiene styrene (SBS) block copolymers comprise of two phases structured domains involving polystyrene “hard” domains and butadiene “soft” domains. The styreneic domains provide a physical crosslink that enables SBS to behave like a highly flexible thermoplastic elastomer. Recently, with the rise of smart elastomers, SBS‐based matrices are being extensively used in transforming them into elastomers that can exhibit shape change when excited with a range of stimuli (shape memory elastomers). With the advantages of long‐range elasticity, reprocessability, and ability to be modified into various tailor‐made shape morphing elastomers, the use SBS‐based elastomers has exceptionally risen in the scope of deployable structures temperature sensors, snap fittings, and actuators. This review attempts to tether the recent development in SBS‐based shape memory polymers along with highlighting the fabrication routes and the shape memory mechanistic pathway. The review introduces the concept of shape memory polymers, classification, and their characterization, followed by shape memory elastomers and finally one way/two‐way SBS‐based shape memory elastomers. In an attempt to blend both the scientific and the engineering realm, the narrative provides a concise overview of SBS‐based shape morphing polymers' expanding boundaries.

Multilayer Microstructured High-Sensitive Ultrawide-Range Flexible Pressure Sensor With Modulus Gradient

Flexible pressure sensors have been widely studied due to their potential applications in wearable electronics. However, the poor sensitivity and narrow working range seriously hinder their developments in practical applications. This article reports a flexible pressure sensor characterizing with modulus gradient and multilayered microstructure. The sensor has an ultrahigh sensitivity of 29.69 kPa_−1 due to the gradient structure formed by low modulus Ag/hydrogenated styrene-butadiene block copolymer (SEBS) electrode layer and high modulus graphene (GR)/carbon nanotubes (CNTs)/polycaprolactone (PCL) composite with surface microstructure. The sensor has an ultrawide measurement range of 0–500 kPa due to its multilayered structure. In addition, the sensor has good linearity (4.85%) and repeatability (2.18%), rapid response time (50 and 30 ms), low detection limit (30 Pa), and long-term durability (1000 cycles). Experimental results suggest that the sensor can be used for effective detection of mechanical vibrations, pulse, and human motions and can also be used for measuring spatial pressure distribution after being arrayed. These applications indicate its great potential in wearable medical devices and electronic skins.

Influence of High Viscosity Petroleum Resin (HV-PR) on the Intermediate and High Temperature Performances of Styrene–Butadiene–Styrene Block Copolymer (SBS) Modified Bitumen

Influence of High Viscosity Petroleum Resin (HV-PR) on the Intermediate and High Temperature Performances of Styrene–Butadiene–Styrene Block Copolymer (SBS) Modified Bitumen

Preparation and characterization of CQDs/SBS composites and its application performance as asphalt modifier

This research aims to use the prepared bio-base carbon quantum dots/styrene–butadiene styrene block copolymer (CQDs/SBS) composite materials as asphalt modifiers based on Pickering emulsion polymerization. The physical and chemical properties of CQDs/SBS composite modifier and its effect on asphalt modification were researched and contrasted it with SBS modifier. The results show that strong van der Waals forces and chemical covalent bonds are formed between CQDs and SBS polymer chains through a series of physicochemical reactions, resulting in strong interactions. Thus CQDs are uniformly dispersed in the SBS phase to form a homogeneous composite material. With the addition of CQDs, the CQDs/SBS composite modifier with slightly lower molecular weight than SBS modifier and can be better dispersed in asphalt. In addition, CQDs/SBS composite modifier has better thermal stability. Furthermore, CQDs and SBS have a synergistic impact in progressing the high-temperature property of polymer modified asphalt (PMA), which is showed by the improvement in softening point, viscosity, rutting resistance, and elastic recovery rate of CQDs/SBS PMA. However, the low-temperature property of CQDs/SBS PMA decreased, which is manifested by decreased penetration and ductility, increased creep stiffness modulus (S), and decreased the rate of change of stiffness with time (m). Further, CQDs/SBS PMA appears superior better storage stability than SBS PMA. It has the preferences of facile preparation procedure and low cost too, making it a beneficial choice for asphalt modifiers.

Phase structure characterization and compatibilization mechanism of epoxy asphalt modified by thermoplastic elastomer (SBS)

Epoxy resin is widely used in thermosetting polymer modified asphalt. However, the delamination and segregation will occur owing to the poor compatibility between epoxy resin and asphalt. The rigid molecular structure of epoxy resin also leads to insufficient toughness of epoxy asphalt (EA) at low temperature. In order to solve these problems of EA, styrene butadiene styrene block copolymer (SBS) is used to prepare modified epoxy asphalt (SBS-EA). The phase separation microstructure, rheological properties, mechanical properties and compatibilization mechanism of SBS-EAs are investigated. The initial viscosity of EA is increased by introducing SBS, but it still satisfies the requirement of pavement. The results of fluorescence microscopy and micro-computed tomography reveal that the compatibility of EA can be significantly improved by 3 wt% SBS. The average particle size of dispersed phase asphalt can be reduced with the content of SBS. Micro-infrared and gel permeation chromatography quantitative analysis turn out that SBS will migrate from the base asphalt to epoxy resin crosslinking network. The tensile strength, elongation at break and toughness of 3%SBS-EA are 12%, 67% and 78% higher than those of EA due to the good phase separation structure. Furthermore, the dispersed asphalt phase size is closely correlated with the mechanical properties of SBS-EA.