Styrene–butadiene–styrene Rubber Research Articles

Effect of High Polymer, Crumb Rubber, and Epoxy-Modified Asphalt Binders on Laboratory Performance of Open-Graded Friction Course Mixtures

Open-graded friction course (OGFC) is a thin asphalt mixture surface layer. It is gap-graded with a high percentage of coarse aggregates that are nearly uniform in size, resulting in a high percentage of interconnected air voids and asphalt binder, which provides improved skid resistance, visibility, and decreased pavement–tire noise. However, construction personnel at the Louisiana Department of Transportation and Development reported that conventional OGFC mixtures have durability issues and shorter service life, compared with thin asphalt mixture lifts. Hence, effects of different asphalt binder types on the performance of OGFC mixtures were evaluated. Five types of asphalt binder were utilized: conventional styrene-butadiene-styrene (SBS) asphalt binder PG 76-22M; high SBS content asphalt binder PG 88-28; diluted epoxy asphalt (EA) binder with two different dosages (25% and 50%); and a hybrid modified asphalt binder prepared with SBS and crumb rubber modifier PG 76-22G. The optimal aggregate structures were determined based on minimum required air voids and voids in coarse aggregate. Physical and mechanical tests were conducted to assess the performance of OGFC mixtures, including draindown, permeability, loaded wheel track, and Cantabro abrasion loss. Results indicate that OGFC mixtures incorporating diluted EA binder exhibited lower draindown values than mixtures containing PG 76-22M and PG 88-28. Moreover, mixtures with PG 88-28 and 50% EA binders demonstrated improved resistance to rutting. Mixtures with 50% EA and PG 88-28 binders demonstrated improved durability, compared with mixtures with PG 76-22M for unaged and aged conditioning, as measured by Cantabro abrasion loss values.

Durability of the effectiveness of atmospheric plasma treatment applied to thermoplastic Styrene-Butadiene-Styrene (SBS) rubber

ABSTRACT The study examines the impact of atmospheric air plasma treatment on Styrene-Butadiene-Styrene (SBS) thermoplastic rubber. The durability of the modifications and their effect on adhesive properties were evaluated over 21 days, with and without adhesive, under specific temperature and humidity conditions (23°C, 50% Relative Humidity). Adhesion performance of plasma-treated SBS rubber joints using water-based polyurethane adhesive (WPU) was assessed, considering treatment speed, adhesive application after plasma treatment, and storage time. Results show that plasma treatment increases SBS rubber’s surface energy, introduces roughness, and creates polar functional groups, enhancing adhesion. However, adhesion values varied with treatment speed, immediate adhesive application after plasma treatment, and storage time. Samples treated solely with plasma and without adhesive exhibited declining adhesion over time. Conversely, samples with adhesive applied directly after plasma treatment maintained relatively constant adhesion, slightly decreasing over time. The findings stress the importance of optimising plasma treatment parameters and considering various factors to ensure long-lasting and reliable adhesion of SBS rubber materials for footwear applications. Atmospheric air plasma treatment impacts adhesion in SBS rubber, depending on factors like treatment speed, adhesive timing, and storage, emphasizing the need for optimisation.

Preparation and performance analysis of high-viscosity asphalt containing high-content SBS and crumb rubber by oxygen-free high-temperature treatment

Styrene-butadiene-styrene (SBS) and crumbed rubber (CR) are widely used for asphalt binder modification in the field of road materials. Especially, the high-viscosity asphalt with high-content SBS/CR modifiers has been applied for constructing the porous pavement and ultra-thin overlay. However, the workability of the SBS/CR modified asphalt still needs to be improved due to many unswollen polymer particles in the blended system. This work aims to propose an oxygen-free high-temperature treatment method to reduce the viscosity of SBS/CR-modified asphalt at construction temperature for better workability. Viscosities at 60 °C and 180 °C were tested to obtain the content of SBS, CR, and tackifying resin for high-viscosity asphalt; multiple physical tests were conducted to obtain acceptable heating temperature, initial pressure, and reacting time; the two high-viscosity asphalt binders cured under various conditions were compared through physics, chemistry, and rheology properties. The results show that the 70# asphalt incorporating 10% SBS, 6% CR, and 9% (by weight of asphalt binder) resin can prepare ideal high-viscosity asphalt binders. After high-speed shearing, it was recommended that CR-SBS-asphalt blends be cured in the reactor at the initial pressure of 3 MPa and temperature of 200 °C for 45 mins. The improved reaction conditions increased light components in a homogeneous and formed a stable modified asphalt blended system. Hence, the low-temperature performance and workability were improved, despite weakening the rutting resistance, which was still excellent at the high temperature.

Effect of SBS and crumb rubber on asphalt modification: A review of the properties and practical application

Owing to the environmental protection potential and the desirable high performance capabilities, asphalt rubber (AR) and styrene-butadiene-styrene (SBS) modified asphalt have been widely used. However, the poor construction workability and segregation issues of AR, along with the exorbitant cost of SBS modified asphalt, are of the serious problems that plague their application scope. Moreover, SBS/crumb rubber (CR) modified asphalt is gradually becoming widespread and it therefore becomes incumbent to find appropriate ways to mitigate the issues that may limit its use. As a consequence, it becomes crucial to analyze the interaction between CR and SBS modifiers in the composite mixture, as well as evaluate the influence of modifier dosage on the performance of the modified asphalt. This study presents a comprehensive review of the effects of SBS modifier, CR modifier and composite SBS/CR on the performance of modified asphalts. Macro analysis and micro analysis, including analysis on the conventional physical properties, are carried out. It can uncover the interaction between modifier and asphalt, which reveals how the modifiers influence the properties of modified asphalts. This study will serve as a source of invaluable information to researchers, engineers, and designers, informing them the development, potential and challenges of the CR, SBS and SBS/CR modified asphalts, the optimum contents to attain the best performance along with the mechanism involved.

Storage stability characterization and improvement of SBS and crumb rubber composite modified asphalt

The styrene–butadiene-styrene (SBS) and crumb rubber (CR) composite modified asphalt (SBS/CRMA) possesses favourable mechanical performance but poor storage stability. The purposes of this study are aiming to investigate the changes in storage properties of SBS/CRMA and propose a corresponding improvement approach in the laboratory and further provide a storage guidance for the field application. The Fluorescence Microscope and the Fourier Transform Infrared Spectroscopy were applied to investigate the phase distribution state of SBS. While the phase distribution state of CR was investigated by visual inspection of fractural surfaces. The softening point, rutting factor and Zero Shear Viscosity (ZSV) were used to evaluate the storage properties. It was concluded that the CR sank and the obvious separation occurred within 6 h. The SBS floated up and the evident separation happened within 12 h. In terms of performance, the separation was most distinct in 12 h. Additionally, The effects of Sulphur and Naphthenic oil on storage stability were evaluated. The verification of the feasibility was conducted in a field project. It was verified that the binder prepared in the construction site possessed better high-temperature performance and storage stability due to different production processes and tank truck storage. The little difference in the high-temperature performance of SBS/CRMA indicated the feasibility of the storage performance optimisation method.

Effect of Carbon Black Nanofiller on Adhesion Properties of SBS Rubber Surfaces Treated by Low-Pressure Plasma.

Studies on the surface modification of commercial styrene-butadiene-styrene (SBS) rubber with different carbon black (CB) nanofiller content (10–80 parts per hundred parts of rubber (phr)) performed by low-pressure oxygen plasma are presented in this paper. The adhesion properties of the rubber were determined by the peel test for adhesive-bonded joints prepared with a water-based polyurethane (PU) adhesive. The chemical structure and morphology of the SBS rubber surface before and after plasma treatment were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The peel tests showed that the plasma treatment significantly improved the strength of adhesive-bonded joints in the entire range of CB tested, revealing a clear maximum for approximately 50 phr of CB. It was also found that as a result of plasma treatment, functional groups that are responsible for the reactions with the PU adhesive, such as C−OH and C=O, were formed, and their concentration, similar to the peel strength, showed maximum values for approximately 50 phr CB. The occurrence of these maxima was explained using the bound rubber model.

Improvement of organoclay dispersion into polystyrene-based nanocomposites by incorporation of SBS and maleic anhydride-grafted SBS

In this study, organoclay-containing polystyrene (PS)-based nanocomposites were fabricated by extrusion in the presence of thermoplastic elastomer modifiers. Styrene–butadiene–styrene (SBS) rubber was used as the elastomeric compatibilizer and maleic anhydride (MA) was grafted onto SBS rubber at different ratios. Grafting was made via melt blending. Cloisite® 30B was used as the organoclay and it was added to PS and PS/SBS blends using a corotating twin-screw extruder, followed by injection molding. Clay loading was kept constant as 2 wt%, and the elastomer content was varied between 0 and 40 wt% throughout the study. MA grafted SBS enhanced the intercalation/exfoliation of clay layers resulting in higher tensile strength, modulus, elongation at break, and impact strength with respect to neat PS. Composites containing 15 wt% MA grafted SBS displayed the optimum average domain size resulting in the high impact strength without deteriorating the tensile strength and modulus values. Elastomer addition increased the glass transition temperature of the samples due to branching or cross-linking during extrusion. PS and PS/SBS exhibited similar melt flow index values with their organoclay-containing composites. MA acted as a plasticizer and decreased viscosity. Scanning electron microscopy study indicated that dispersion of clay layers was observed at the PS-SBS interphase and also in the elastomer phase. Intercalated and exfoliated structures of organoclay layers were confirmed by X-ray diffraction and transmission electron microscopy analyses.

Fracture Monitoring of SBS and Crumb Rubber Modified Porous Asphalt Mixtures under Compression and Splitting Testing Using Acoustic Emission Technique

An acoustic emission (AE) approach to evaluate the fracture process of porous asphalt mixture (PAM) under compression and splitting testing at different temperatures is presented. Two kinds of PAM, styrene-butadiene-styrene (SBS)-modified porous asphalt mixture (SBSPAM), and crumb rubber and SBS compound-modified porous asphalt mixture (CR/SBSPAM), were investigated and corresponding failure load and AE parameters were obtained. Damage assessments of PAM under compression and splitting testing were carried out using relative AE hits and energy. AE hits and energy had negative correlation with failure load. Damage processes of PAM under compression and splitting testing can be classified into three stages based on variation trends of relative AE hits and energy with load level. The softening effect caused by high temperature can lead to acoustic activity of SBSPAM under compression at a low load level, and the addition of CR can reduce the AE activity caused by the softening effect by improving the temperature susceptibility of binder. Change curves of relative AE hits and energy of CR/SBSPAM are more uniform than those of SBSPAM because of the more stable structure improved by CR modification. The findings of this study can provide references for damage evaluation of PAM using the AE technique.

Fatigue performance characterization and prediction of asphalt binders using the linear amplitude sweep based viscoelastic continuum damage approach

This study assessed the fatigue performance of asphalt binders modified with crumb rubber, waste cooking oil (WCO), and Styrene-Butadiene-Styrene (SBS). The experimental program included linear amplitude sweep (LAS) and time sweep (TS) tests with different loading profiles under various test temperatures. The objective was to compare the fatigue analyses based on the recently proposed GR and WRsum failure criteria within the viscoelastic continuum damage (VECD) modeling framework. Simulation algorithms were developed for the two criteria which allowed for fatigue performance evaluation. The results indicated that the damage characteristic relationship was slightly dependent on test method and strain profile, and the degree of dependence was material specific. The two failure criteria appeared to be fundamental material functions; the GR criterion was temperature dependent but was able to unify both LAS and TS tests, while the WRsum criterion unified both test methods under all temperatures. With respect to modification, an optimum WCO dosage of 3% was identified according to the WRsum criterion for the best fatigue performance. Both the SBS and crumb rubber modifications were observed to significantly improve the fatigue resistance based on the two failure criteria.

Surface Modification of SBS Rubber by Low-Pressure Inert Gas Plasma for Enhanced Adhesion to Polyurethane Adhesive

Surface modification studies of styrene–butadiene–styrene (SBS) elastomer by inert gas plasmas for improving the adhesion to polyurethane (PU) adhesives are presented in this paper. The plasma was generated by an RF discharge (13.56 MHz, parallel plate reactor) in inert gases (argon or helium) under low pressure.To characterize the changes to the SBS surface, peel tests, infrared spectroscopy analysis and contact angle measurements were utilized. Compared with non-treated surface, inert gas plasma treatments were found to result in a significant increase (4–6 times) in adhesion (peel) strength. The maximum value of the peel strength was attained in a very short time of the plasma treatment (5–15 s), after which the value decreased.For relatively longer times (a few minutes), in most cases a re-increase of the peel strength was observed. Functional groups, such as –OH, >C=O, C–O–C, were detected on the plasma-treated SBS surface. The concentration profiles of –OH and >C=O groups vs plasma treatment time (t) revealed maxima, position of which coincided with the peel strength maximum. In contrast, the C–O–C concentration increased systematically with t Furthermore, the dispersion γd s and polar γp s components of the surface free energy increased also monotonically with t approaching constant levels. These results confirmed the chemical nature of the bonding between the SBS surface and polyurethane adhesive. They also suggested that three main effects were associated with the inert gas plasma treatment process, namely: formation of free radicals, crosslinking and probably plasma etching of the SBS surface. Then, after contact with air, subsequent reactions with O2 and H2O vapor took place. On this basis, a kinetic model was proposed, which was capable of describing the strength of SBS–PU joints as a function of t. The model indicated that ion bombardment was a possible mechanism for the free radical formation on the SBS surface treated by inert gas plasmas. © Koninklijke Brill NV, Leiden, 2012

Influence of Additives in Adhesion of UV Radiation Surface-Treated SBS Rubber

In this study, the effect of additives (oils, lubricants) included in the formulations of different block styrene–butadiene–styrene (SBS) rubbers on the effectiveness of the ultraviolet (UV) radiation treatment to improve adhesion to polyurethane adhesive was analyzed. The modifications on the UV-treated rubber surfaces for different lengths of treatment have been characterized by contact-angle measurements (ethylene glycol, 25°C), Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). The adhesion properties have been evaluated from T-peel strengths of treated rubber/polyurethane adhesive/leather joints. The UV-radiation treatment on all rubber surfaces produced an increase in wettability, carbon–oxygen polar moieties, and ablation. The oxidation degree produced on the rubber surface treated with UV radiation was less when oils and lubricants were included in the formulation, likely due to competition of the oxidation process with the migration of low-molecular-weight additives to the rubber surface. On the SBS2 rubber surface (rubber containing carbon black and calcium carbonate fillers), the migration of oils and lubricants was also produced during the UV-radiation treatment, but a decrease in adhesion occured likely due to the lower tensile strength and higher extent of oxidation produced by the UV radiation treatment.

Water-based chlorination treatment of SBS rubber soles to improve their adhesion to waterborne polyurethane adhesives in the footwear industry

Solutions of trichloroisocyanuric acid (TCI) in different organic solvents are commonly employed in the footwear industry to improve the adhesion of SBS (styrene-butadiene-styrene) rubber soles to polyurethane adhesive. To avoid the use of organic solvents in the chlorinating solutions, several water-based chlorinating treatments were investigated in this study: (i) inorganic chlorine compounds (HCl-acidified sodium hypochlorite solution; free active chlorine (FAC) = 47.8 g/l); (ii) organic chlorine donors (aqueous solution of 3 wt% TCI/H2O, and ethanol solutions of 3 wt% HD (1,3-dichloro-5,5-dimethylhydantoine), or NCS (N-chlorosuccinimide); (iii) organic chlorine donor salts (aqueous solutions containing 3 wt% DCI (sodium dichloro isocyanurate), CB (chloramine B, N-chloro-sodium-phenylsulphenamide), or CT (chloramine T, N-chloro-sodium-p-toluenesulphenamide). The surface modifications produced by treatment of SBS rubber with the aqueous chlorinating agents were compared with those obtained by using the current solvent-based chlorinating treatment (3 wt% TCI/MEK). The FAC concentration and the chlorine stability in the solutions were determined by iodine titration, and the SBS rubber surface pH was determined with a flat pH probe. The surface modifications on the SBS rubber were analyzed by ATR-IR spectroscopy, XPS, contact-angle measurements and SEM. The adhesion properties were evaluated by T-peel strength tests on treated SBS rubber/waterborne polyurethane adhesive/roughened leather joints. The failed surfaces obtained after peel tests were analyzed by ATR-IR spectroscopy to precisely assess the locus of failure of the adhesive joints. The nature of the modifications produced on the SBS rubber surface depended on the chlorinating system used, the SBS rubber surface pH value, and the free active chlorine concentration of the chlorinating solution. The most effective chlorinating agents were TCI/H2O and HD/EtOH, but they were not stable over time due to quick chlorine evolution. Treatment with NaClO/HCl and DCI/H2O provided acceptable adhesive strength values although there was fast chlorine evolution in the NaClO/HCl solution; the free active chlorine concentration in the DCI/H2O solution was stable for at least 4 days after preparation. Finally, the treatment with NCS/EtOH, CB/H2O and CT/H2O did not chemically modify the SBS rubber surface, so the adhesion to polyurethane adhesive was not improved.

Influence of calcium carbonate added to the SBS rubber formulation on the surface modifications produced by halogenation

To improve the adhesion properties of styrene–butadiene–styrene (SBS) rubber sole to polyurethane adhesive, surface treatments are required, of which halogenation with trichloroisocyanuric acid (TCI) solutions in organic solvents is the most commonly used treatment in the footwear industry. Calcium carbonate filler is commonly added to improve the mechanical properties and to reduce shining of SBS rubber formulations. The influence of the filler on the effectiveness of surface chlorination of SBS rubber had not been considered in the existing literature. Therefore, 10 wt% calcium carbonate filler was added to the SBS rubber formulation and the surface modifications and adhesion properties produced by treatment with TCI solutions were investigated. The resulting surface modifications and adhesion were compared to those obtained in unfilled SBS rubber. It is shown that the treatment with TCI solutions was less effective in the calcium-carbonate-filled SBS rubber and a lower peel strength to polyurethane adhesive was obtained; however, a cohesive failure in the rubber was always obtained.

Chemical modification of styrene–butadiene–styrene (SBS) rubber by reactive grafting with maleic anhydride

A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The influence of the reactive grafting on the surface properties of SBS has been studied with special emphasis on the improvement of the adhesion to polyurethane adhesive. The grafting of MA onto SBS was carried out in the presence of different concentrations of 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals by thermal decomposition, which induce the grafting reaction. The modification process was performed in the molten state using a Brabender mixer to premix the reactants and a hot press to initiate the functionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting of MA on SBS. The changes in wettability on the modified SBS rubber were determined by contact angle measurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/polyurethane adhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presence of a weak carbonyl vibration at 1700 cm-1 in the ATR-IR spectra and by the carbon- oxygen band at a binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MA amount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA. Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. The wettability of the modified rubber increased with respect to the original polymer, new carbon-oxygen moieties were created and the C/O ratio increased. A noticeable enhancement in peel strength values was observed, which was ascribed to the creation of interfacial interactions between the polyurethane and the SBS rubber surfaces.

UV treatment of synthetic styrene-butadiene-styrene rubber

The effectiveness of the treatment with ultraviolet light (UV) on several polymeric surfaces has previously been established. In this study, a low pressure mercury vapour lamp was used as a source of UV radiation for the surface treatment of a difficult-to-bond block styrenebutadiene-styrene rubber (S6), the treatment time ranging from 10 s to 30 min. The UV-treated S6 rubber surfaces were characterized by contact angle measurements (ethylene glycol, 25°C), ATR-IR spectroscopy, XPS, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). T-peel tests on UV-treated S6 rubber/polyurethane (PU) adhesive/ leather joints (before and after ageing) were carried out to quantify adhesion strengths. The UV treatment of S6 rubber produced improved wettability, the formation of C—O, C=O and COO- moieties, and ablation (removal of a thin rubber layer from the surface). The extent of these modifications increased with increasing treatment time. The extended UV treatment produced greater surface modifications, as well as the incorporation of nitrogen moieties at the surface. Furthermore, noticeable ablation of S6 rubber surface occurred. Peel strength values increased with increased treatment time of UV treatment of S6 rubber. Also, with increasing treatment time, the adhesive joints showed different loci of failure: adhesional failure for the as-received and 2 min-UV treated S6 rubber/polyurethane adhesive/leather joints changed to mixed failure (cohesive in the treated S6 rubber + adhesional failure) for the 30 min-UV treated S6 rubber/polyurethane adhesive/leather joint.

Morphology and toughening mechanisms in clay-modified styrene-butadiene-styrene rubber-toughened polypropylene

Clay-modified styrene-butadiene-styrene (SBS) rubber is utilized to toughen polypropylene (PP). The SBS rubber is found to have good compatibility with clay particles. SBS rubber helps to finely disperse clay particles in PP matrix. Mode-I fracture mechanisms are investigated using optical microscopy and transmission electron microscopy techniques. Rubber particle cavitation and matrix shear yielding are found to be the main toughening mechanisms in PP/SBS system. In the case of PP/SBS/clay system, widespread rubber particle cavitation, which appears to be facilitated by the presence of clay particle inclusions inside the SBS rubber particles, takes place in the PP matrix. This, in turn, leads to the formation of a bigger shear yielded zone in PP matrix. As a result, an enhanced toughness is observed.

Chlorination of SBS rubbers with different styrene contents using trichloro-isocyanuric acid

In order to improve their adhesion to polyurethane adhesives, three unvulcanized block styrene-butadiene-styrene (SBS) rubbers with styrene contents between 33% and 55% were surface-treated with solutions of 2 wt% trichloro-isocyanuric acid (TCI) in ethyl acetate. The joint strength was estimated using T-peel tests and the failed surfaces were analyzed to assess the locus of failure. The failed surfaces were analyzed using ATR-IR spectroscopy, contact angle measurements, XPS, and SEM. An unexpected trend in the joint strength was obtained because the locus of failure depended on both the styrene content and the mechanical properties of each SBS rubber. A mixed mode of failure was obtained in joints produced with S 1 rubber (33 wt% styrene content), whereas failure in the chlorinated layer was observed with S3 rubber (55 wt% styrene content); cohesive failure in the adhesive was found for the joints produced with S2 rubber (44 wt% styrene content).