Photoinitiator grafted styrene–butadiene–styrene triblock copolymer

Grafting of photoinitiator-4-maleimidobenzophenone (4-MBP) onto styrene–butadiene–styrene (SBS) triblock copolymer was carried out by free radical polymerization. The grafting ratio was evaluated by varying initiator concentrations, and the structure of grafted copolymer (SBS-g-MBP) was characterized by attenuated total reflectance infrared Fourier transform spectroscopy (ATR-FTIR), proton nuclear magnetic resonance (¹H NMR) and X-ray photoelectron spectroscopy (XPS). The results confirmed that 4-MBP was successfully grafted onto the SBS backbone. Thermal gravimetric analyzer (TGA), dynamic mechanical thermal analysis (DMTA), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to study the thermal properties and morphology of the SBS-g-MBP. From the data of TGA, the SBS-g-MBP had better thermal stability compared with that of SBS. DMTA testing indicated that the glass transition temperature (T_g) of SBS-g-MBP was higher than that of SBS. With the aid of SEM and AFM, the structure of micro-phase separation can be observed obviously. What is more, the aggregates become smaller compared with those of pure SBS. The experiment of UV-crosslinked SBS-g-MBP revealed that the gel fraction could be facilely controlled by adjusting grafting ratio and exposure time. The results suggested that this novel grafted copolymer could be attractive for its application in biomedical materials such as medical pressure-sensitive adhesive.     

Rheology of asphalt and styrene–butadiene blends

In recent years, many authors have researched polymer-modified asphalt blends and tried to better understand the rheological behavior of these materials. In this work, the thermomechanical response of an asphalt formulation was researched trying to find better asphalt-modified blends that allow for the construction of improved asphalt roads. The experimentation included several polymer–maltene formulations developed at different polymer concentrations and temperatures where the asphaltenes of the original asphalt were removed. Such separation was carried out because the maltene fraction represents the portion of the asphalt that chemically reacts with the polymer modifier. The rheological behavior of the blends was determined from oscillatory shear flow data. Analysis of the G′, G′′, G* moduli and phase angle (δ) as a function of oscillatory frequency for various temperatures led to the conclusion that the maltenes behaved as a pseudo-homogeneous viscoelastic material that could dissipate stress without presenting structural changes. Furthermore, all maltenes–polymer blends behaved more viscoelastically than the non-blended maltenes depending on the amount of the polymer contained in the formulation. The blend viscosity increased with polymer concentration, and this increase was seen in both the viscous and elastic moduli. Furthermore, performance grade trials were also performed according to the AASHTO TP5 to determine the failing temperature. It was noticed that the limiting temperature increased with the modifier concentration with a δ between 50° and 60°, indirect value of elasticity found to have industrial applications for asphalt pavements.     

Pavement performance evaluation of recycled styrene–butadiene–styrene-modified asphalt mixture

More and more styrene–butadiene–styrene (SBS)-modified asphalt waste materials are being discarded with the increase in road service life. The recycling of these waste pavement materials can reduce environmental pollution and help save resources. However, the low-temperature performance and the fatigue resistance of recycled asphalt mixture are significantly affected by the addition of reclaimed asphalt pavement (RAP). In order to evaluate the low-temperature performance and the fatigue resistance of recycled SBS-modified asphalt mixture, three points bending test, Fénix test and Ensayo de BArrido de DEformaciones test were conducted. Additionally, the differences of recycling between SBS-modified RAP with different ageing conditions and ordinary unmodified RAP were compared. The results showed that fatigue resistance of modified recycling of asphalt mixture with different RAPs did not vary much under low temperature (?5 °C) while displaying an obvious difference under higher temperature. SBS-modified RAP under light ageing condition was suitable for modified recycling. However, the SBS-modified asphalt from RAP under serious ageing condition would lose modification effect resulting in a great reduction of the low-temperature crack resistance and the fatigue resistance. Therefore, it is necessary to evaluate the ageing degree of RAP before recycling SBS-modified asphalt mixture. The SBS-modified RAP under serious ageing condition (SM-RAP) is not recommended for directly modified recycling. But considering for further utilisation, the SM-RAP used for unmodified recycling as ordinary unmodified RAP can be regarded as a good choice and the RAP content should be restricted to less than 30%.     

Partial inhibition of acrylonitrile–butadiene–styrene dust explosion by sodium bicarbonate

During acrylonitrile–butadiene–styrene (ABS) plastic processing, dust explosions could occur in production and transportation. In this paper, the explosion properties and pyrolysis mechanism of ABS dust were studied. The inhibition effects of sodium bicarbonate (NaHCO₃) on ABS dust were investigated using the 20-L explosion chamber, Hartmann tube, and G-G furnace. The results demonstrated that NaHCO₃ effectively decreased both the ignition sensitivity and the explosion severity of ABS dust explosion by increasing the mass fraction of the inhibitor. Adding 50 wt% NaHCO₃ could reduce the explosion hazard to an acceptable level. Combined with an analysis of gas phase products and thermal decomposition behaviour, it was discovered that incorporating NaHCO₃ enhanced the heat stability of ABS dust. The decomposition of added NaHCO₃ produced a substantial quantity of CO₂, consuming many free radicals especially OH• and H•, which further reduced the decomposition temperature of ABS. The inhibitor effectively interrupted the combustion chain reaction and inhibited the propagation of the explosion. The results establish a scientific and operational basis for the prevention and management of dust explosion hazards in the ABS processing field.     

Enhancing mechanical properties of styrene–butadiene rubber/silica nanocomposites by in situ interfacial modification with a novel rare-earth complex

In this study, a novel rare-earth complex, dithio-aminomethyl-lysine samarium (DALSm), was prepared and then was employed as activator, accelerator, cross-linker and interfacial modifier to improve the mechanical properties of SBR/silica nanocomposites. The results showed that 6 phr DALSm performed a higher vulcanization efficiency than the combination of 5 phr activator zinc oxide (ZnO), 2 phr stearic acid (SA), and 2 phr accelerator diethyl dithiocarbamate zinc (EDCZn). Meanwhile, the XPS and FTIR analysis of DALSm/silica model compounds confirmed that hydrogen bonds and coordination bonds could be formed between DALSm and silica during vulcanization process, which can effectively facilitate the homogenous dispersion of silica particles into SBR matrix and enhance the interface adhesion between rubber matrix and filler. As a consequent, the mechanical properties of SBR/DALSm/silica nanocomposites were substantially improved and much more excellent than those of the SBR/EDCZn/silica nanocomposites containing equivalent filler content. Based on the results of immobilized polymer layer, the reinforcing mechanism of DALSm in SBR/silica nanocomposites was analyzed.     

Thermal resistance and dynamic damping properties of poly (styrene–butadiene–styrene)/thermoplastic polyurethane composites elastomer material

We present the preparation of novel thermoplastic composites elastomer material based on poly (styrene–butadiene–styrene) (SBS), ester-type polyurethane (TPU-EX) and ether-type polyurethane (TPU-ER) materials via melt blending. A series of studies were conducted on the relationship between their morphology, thermal resistance, mechanical properties, and dynamic damping properties, given different compositions. An important feature of the SBS/TPU composites elastomer materials of all compositions is their uniform transparency, because the particles are very small with a narrow size distribution and the refractive indices of SBS and TPU are coincide. Additionally, the thermal resistance, dynamic damping properties and mechanical properties of SBS before and after thermal aging are improved as the amount of added TPU is increased, suggesting that blending SBS with TPU is consistent with the compound rule. In addition, the SBS/TPU composites elastomer materials have better dynamic damping properties at high frequency.     

Plating on acrylonitrile–butadiene–styrene (ABS) plastic: a review

ABS is an engineering plastic that has butadiene part uniformly distributed over the acrylonitrile-styrene matrix. It possesses excellent toughness, good dimensional stability, easy processing ability, chemical resistance, and cheapness. However, it suffers from inherent shortcomings in terms of mechanical strength and vulnerability to environmental conditions. Furthermore, it is non-conducting and easily fretted. Plating on ABS can serve to enhance the strength and structural integrity as well as to improve durability and thermal resistance resulting in metallic properties on the ABS material. ABS is described as the most suitable candidate for plating because it is possible to deposit an adherent metal coating on it by only the use of chemical pretreatment process and without the use of any mechanical abrasion. This article aims to review the history of ABS plastics, properties of ABS, processes and mechanisms of plating, and studies of plating on ABS involving mainly eco-friendly methods of plating by discussing the literature published in recent years. The details of electroplating of ABS carried out in the authors’ laboratory are also presented.     

Application of carboxylated styrene–butadiene emulsion-Portland cement mixture as road base material

This study investigated the effects of the addition of a carboxylated styrene–butadiene emulsion (CSBE) and Portland cement on the long-term performance of road base. The specimens stabilised with Portland cement (0–6%) and CSBE (5–10%) were subjected to different stress sequences in order to study the unconfined compressive strength, flexural strength (FS), soaked and unsoaked California bearing ratio, dynamic creep and wheel-tracking characteristics of seven-day-cured specimens. The FS tests showed that the addition of a 4% Portland cement–7% CSBE mixture resulted in improvements of 48.9% of modulus of rupture as compared to the sample with 4% cement. The permanent strain behaviour of the samples was assessed by the Zhou three-stage creep model. The results of dynamic creep and wheel-tracking tests showed that the permanent deformation characteristics were considerably improved by the addition of a 4% Portland cement–7% CSBE mixture, which resulted in reduction of permanent strain of the mixture. Therefore, this research presents a new polymer additive with outstanding engineering properties for use in road bases.     

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

The microstructure and fracture performance of an anhydride-cured epoxy polymer modified with two poly(styrene)-b-1,4-poly(butadiene)-b-poly(methyl methacrylate) (SBM) block copolymers were investigated in bulk form, and when used as the matrix material in carbon fibre reinforced composites. The ‘E21’ SBM block copolymer has a higher butadiene content and molecular weight than the ‘E41’. A network of aggregated spherical micelles was observed for the E21 SBM modified epoxy, which became increasingly interconnected as the SBM content was increased. A steady increase in the fracture energy was measured with increasing E21 content, from 96 to 511 J/m² for 15 wt% of E21. Well-dispersed ‘raspberry’-like SBM particles, with a sphere-on-sphere morphology of a poly(styrene) core covered with poly(butadiene) particles, in an epoxy matrix were obtained for loadings up to 7.5 wt% of E41 SBM. This changed to a partially phase-inverted structure at higher E41 contents, accompanied by a significant jump in the measured fracture energy to 1032 J/m² at 15 wt% of E41. The glass transition temperatures remained unchanged with the addition of SBM, indicating a complete phase separation. Electron microscopy and cross polarised transmission optical microscopy revealed localised shear band yielding, debonding and void growth as the main toughening mechanisms. Significant improvements in fracture energy were not observed in the fibre composites, indicating poor toughness transfer from the bulk to the composite. The fibre bridging observed for the unmodified epoxy matrix was reduced due to better fibre–matrix adhesion. The size of the crack tip deformation zone in the composites was restricted by the fibres, hence reducing the measured fracture energy compared to the bulk for the toughest matrix materials.     

Freeze–thaw performance of base course treated with carboxylated styrene–butadiene emulsion–Portland cement

Freeze–thaw (FT) cycles and moisture susceptibility are important factors influencing the geotechnical characteristics of soil–aggregates. Given the lack of published information on the behaviour of base course materials stabilised with styrene butadiene emulsions (SBE) and cement–SBE-treated base (CSBETB) under environmental conditions, especially freezing and thawing, this study investigated the effects of these additives on the CSBETB performance. The primary goal was to evaluate the resistance of CSBETB to moisture damage by performing FT, Marshall conditioning and AASHTO T-283 tests and to evaluate the long-term stripping susceptibility of CSBETB while also predicting the liquid antistripping additives to assess the mixture’s durability and workability. Specimens were stabilised with Portland cement, SBE and a Portland cement–SBE mixture and cured for 7 days, and their short- and long-term performances were studied. Test evaluation results show that the additions of additives increase the resistance of the mixtures to moisture damage. Results of durability tests performed for determining the resistance of compacted specimens to repeated FT cycles indicate that the specimen with the 4% cement–8% SBE mixture significantly improves water absorption, volume changes and weight losses. This indicates the effectiveness of this additive as a road base stabiliser with excellent engineering properties.     

Nanocomposites based on MWCNT and styrene–butadiene–styrene block copolymers: Effect of the preparation method on dispersion and polymer–filler interactions

Composites of Kraton-D® 1102 BT (a styrene–butadiene–styrene block copolymer) and multi-walled carbon nanotubes (MWCNTs) were prepared by melt mixing. The composites were characterized by electrical conductivity measurements (Coleman’s method), mechanical properties (DMA and stress–strain tests), thermal stability (thermogravimetry) and morphology of dispersion (SEM). Finally, the resulting composites were compared with those made by the solution casting method. The results showed a strong influence of the preparation methodology on the final properties of the composites due to changes in morphology. Composites prepared by casting showed a higher electrical conductivity than extruded ones; the composites with 6 wt.% of MWCNT prepared by extrusion presented conductivity of the same order of magnitude as the composite with 1 wt.% of MWCNT prepared by casting – 10⁻³ to 10⁻⁴ S cm⁻¹. However, the extruded samples presented better mechanical properties than the casting ones.     

Development of polycarbonate/acrylonitrile–butadiene–styrene copolymer based composites with functional fillers for car audio chassis

Environmental regulations require the improvement of automobile fuel efficiency. This can be achieved mainly by reducing the weight of automobile components. In this study, polycarbonate/acrylonitrile–butadiene–styrene copolymer (PC/ABS) based composite mixed with glass fibers and metal fibers was developed and its suitability of application into car audio chassis was investigated. The test materials were prepared with various contents of metal fibers because of the fibers’ excellent mechanical and electrical properties. In this study, the morphologies of the materials were investigated to confirm the dispersion of the fillers and the interfacial characteristics between the fillers and the base material. In addition, the mechanical and electrical characteristics of the PC/ABS based composites, which depended on the metal fiber content, were evaluated using key mechanical (impact, tensile and flexural) and electrical tests such as electromagnetic interference (EMI) and surface resistance. The proper proportion of the metal fibers in PC/ABS based composites was determined from the test results. Finally, the applicability of PC/ABS based composites in car audio chassis was evaluated through weight reduction analysis and cost-benefit analysis.     

Thermo-rheological behavior and compatibility of modified asphalt with various styrene–butadiene structures in SBS copolymers

The knowledge of the morphological structure or effect of polymer structure on the performance of polymer-modified asphalt (PMA) is not systematic and completed yet. In this paper, SBS-modified asphalts were prepared by asphalts with different compositions and styrene–butadiene–styrene (SBS) copolymers with various styrene–butadiene structures, which in turn were subjected to frequency sweep tests, viscous measurements and fluorescence microscopy. The results revealed that the SBS-modified asphalt containing 30 wt.% styrene had the optimal viscoelastic functions and the highest viscosity, indicating enhanced viscoelastic characteristics and less sensitivity to temperature changes. Furthermore, it is less susceptible to shear forces for asphalts as the increase of styrene content because larger and stronger aggregated polystyrene domains can render deformation and movement more difficult. For system studied, the compatibility becomes poorer as the increase of styrene contents and polymer phase sizes decrease with the enhancement of styrene contents as well as their volume proportions. The scope of distribution curves becomes narrower and the swelling degree is lower as the increase of styrene contents by image analysis. As a conclusion, there is a moderate styrene content for SBS to acquire equilibrium between the compatibility and viscoelastic characteristics.     

One-step synthesis of Co–Ni ferrite/graphene nanocomposites with controllable magnetic and electrical properties

Co_1−xNi_xFe₂O₄/graphene nanocomposites were synthesized through a one-step solvothermal method. The as-synthesized products were characterized by X-ray powder diffraction, field emission scanning microscopy, transmission electron microscope, and high-resolution transmission electron microscope. The results show that the Co_1−xNi_xFe₂O₄ nanoparticles are uniformly dispersed on graphene sheets. The dependence of structure, magnetic and electrical properties of Co_1−xNi_xFe₂O₄/graphene nanocomposites on the Ni²⁺ concentration and the graphene content were also studied. The saturation magnetization and electrical conductivity of the as-prepared products reached 51.82 emu/g and 1.00 × 10² S/m, respectively.     

On the sol–gel synthesis and characterization of strontium ferrite ceramic material

A simple oxalate based sol–gel process has been described to produce a highly stable anion deficient strontium ferrite for separation of oxygen from air. The method involves metal nitrates and oxalic acid precursors with ethanol and water as solvents, gel formation, digestion for 4 h, drying at 150 °C for 24 h, and finally decomposition at 800 °C in air. The resulting material (i) exhibits a single perovskite-type cubic (SrFeO_3?ξ; ξ ～ 0.13) phase with a_o = 3.862 ± 0.002 Å, (ii) contains both the Fe⁴⁺ and Fe³⁺ species in 2.8:1 ratio, (iii) undergoes Fe⁴⁺ → Fe³⁺ reduction upon heating at 650 °C in rare gas ambient and transition to an orthorhombic phase with a ～ a_o√2, b ～ 4a_o, c ～ a_o√2, which reverts back to cubic phase with oxygen uptake at elevated temperatures, and (iv) acts as filter for air with excellent oxygen permeation, typical flux density value being 2.45 ml/cm² min at 1000 °C.     

Novel aqueous sol–gel preparation and characterization of barium M ferrite, BaFe12O19 fibres

Gel fibres of barium M ferrite, BaFe12O19, were blow spun from an aqueous inorganic sol and calcined at temperatures up to 1200°C. The ceramic fibres were shown by X-ray diffraction to be single phase crystalline M ferrite at 1000°C, and surface area and porosity measurements indicated an unusually high degree of sintering at this temperature. The fibres also demonstrated a favourable grain structure of less than 0.1 m at this temperature and maintained a small grain size of less than 4 m even up to 1200°C, an important factor in the magnetic properties of this material.     

Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well.