Styrene-butadiene Rubber Latex Research Articles

Synergic Effects of Recycled Concrete Aggregate and Styrene Butadiene Rubber (SBR) Latex on Mechanical Properties of Concrete

These days Sustainable advancement is picking up notoriety all around the globe. To hold characteristic assets, reuse and reusing of development and annihilation squander is the clearest approach to achieve manageability in the development division. Presently, reused aggregate RA is been generating and CDW is its source. As of late, these squanders are reused in present day reusing offices, under great quality control arrangements which could prompt enhance its execution. An investigation is completed about the characteristics of Recycled Aggregate Concrete RAC by utilizing squashing and breaking of concrete waste got from various obliteration locales & junkyard. With the end goal to upgrade the characteristics of RAC there are a few additives called as super plasticizer which are adjoined with concrete. Fixings utilized in particularly this investigation were ordinary sand, common & reused aggregate & additive namely Styrene Butadiene Rubber latex (SBR). Those aggregates are acquired from various assets. Sum of 144 concrete molds in system of 4 collections was framed. Gatherings were structured in such a route along these lines, to the point that the impact of reused coarse aggregate (half, 75 percent, and 100 percent), cement dose and expansion of latex of SBR in factor amounts by the cement weight of (0.5 percent, l percent, 1.5 percent) ought to be appropriately decided. For compressive quality and rupture modulus MOR, tests were done. Prior to the tests performance in the research center a diminishing pattern of twenty five (25) percent in compressive quality was taken note. An impressive decrease was seen in the properties of RAC by utilizing 100% reused aggregate when contrasted with Natural Aggregate Concrete NAC. There was negligible change in Recycled Aggregate Concrete RAC made of 75 percent (%) NA and 25 percent (%) RCA. Yet, there was ideal properties differences of concrete ended with the blend of half NA and half RCA. It was seen in the outcomes that concrete squanders might be used in arrangement of concrete subsequent to reusing them which at that point can be utilized in many concrete structures.

Study on the properties and microstructure of polymer modified waste printed circuit board cement-based materials

Waste printed circuit boards (WPCB) are solid waste, and the current disposal of WPCB in landfills has raised environmental concern. Existing studies used ground WPCB as a replacement of fine aggregate in cement-based materials, but the performances of those materials were notably decreased. This paper aims to improve the performance of WPCB-bearing cementitious materials using styrene butadiene rubber (SBR) latex and chloroprene rubber (CR) latex. For this purpose, cement-based materials with ground WPCB as fine aggregates were prepared, and the effects of SBR latex and CR latex on the mechanical properties of WPCB-bearing samples with varying dosages were studied. The influence mechanism was studied using SEM, hydration heat, XRD, and FTIR tests. The results showed that the incorporation of ground WPCB tends to significantly reduce the compressive strength of cement-based materials, while the addition of SBR and CR latex can prevent the strength loss. For instance, with the optimal dosage of 5 % for SBR latex or 7.5 % for CR, the 28-d compressive strength of the latex-modified sample was 42.6 MPa and 45.3 MPa, which was 26.78 % and 34.82 % higher than that of the unmodified samples. Through microstructure analysis, it was found that the incorporation of WPCB had a negative impact on the densification of cement-based materials. SBR latex and CR latex promoted the hydration reaction and formed continuous film products inside the structure, which improved the bonding performance of WPCB cement-based materials.

A Study on the Properties of Composite Modified Mortar with Styrene-Butadiene Rubber Latex and Silica Fume.

To solve the problem of the poor abrasion resistance of concrete pavement surface mortar, this study substituted cement with equal amounts of styrene-butadiene rubber (SBR) latex and silica fume (SF) to investigate the effects of organic/inorganic material composite modification on the fluidity, drying shrinkage, mechanical properties, and abrasion resistance of cement mortar. Also in this study, the microstructure, product, and pore structure characteristics of the composite modified cement mortar were investigated using scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and the Brunauer-Emmett-Teller (BET) method. This research found that the sole substitution of SF negatively impacted the mortar's fluidity and drying shrinkage yet enhanced its mechanical strength and abrasion resistance; the incorporation of SBR latex improved fluidity, reduced shrinkage, and increased flexural strength but adversely affected the compressive strength of the mortar. Additionally, the enhancement of the mortar's abrasion resistance with SBR latex was significantly greater than that with SF. When SBR latex and SF were used together as substitutes, the latex struggled to offset the negative impact of SF on mortar fluidity but effectively reduced shrinkage; SF compensated for the detrimental effect of the latex on compressive strength. Moreover, the primary role in enhancing the mortar's abrasion resistance was played by the latex. Microscopic tests showed that SBR latex and SF could increase the content of calcium silicate hydrate (C-S-H) gel, inhibit the formation of ettringite (AFt) and reduce carbonation, refine the pore size of cement mortar, and effectively improve the microstructure of mortar.

Suspension electrospinning of SBR latex combined with photo-induced crosslinking: control of nanofiber composition, morphology, and properties

Suspension electrospinning of a styrene-butadiene rubber (SBR) latex coupled with photo-induced crosslinking in ambient conditions is proposed as a rapid method to prepare ultrafine shape-stable rubber fibrous membranes. Polyethylene oxide (PEO) is used as template polymer and can eventually be removed from the nanostructured membrane by a simple water treatment. A multifunctional thiol crosslinker and an appropriate photo-initiating system are added to the latex to allow the fast and efficient photo-induced crosslinking of the nanofibers, based on thiol addition to the SBR double bonds, as demonstrated by real-time Infrared spectroscopy analyses. It is proved that by varying the PEO template polymer and the thiol crosslinker content, a fine control of the chemical composition, morphology, water solubility, and thermal properties of the nanofibrous membranes is ensured. Moreover, comparable mechanical properties to those of fibrous membranes produced by conventional electrospinning of organic solvent-based solutions are obtained, clearly showing the attractiveness of the present method, especially in terms of process sustainability.Graphical abstract

Compatibility evaluation between waterborne epoxy resin and SBR latex modified asphalt emulsion

Good compatibility between waterborne epoxy resin (WER) modifier and styrene-butadiene rubber (SBR) latex modified asphalt emulsion (SBRE) is an essential premise for good pavement performance of WER and SBR latex compositely modified asphalt emulsion (WSAE). This study aims to explore the compatibility between WER modifier and SBRE. To achieve the goal, several WER modifiers produced by two methods were first selected to modify SBRE, thus the WSAEs were prepared. Next, storage stability and workability of the WSAEs themselves, and high-temperature performance, rheological behavior and temperature sensitivity of their evaporated residues were compared and evaluated via performing a series of experiments, respectively, thus the WER modifier possessing an optimal modification effect was recommended. Results show that the storage stability of WSAEs is sensitive to the amount of WERs. The incorporation of 1% WERs by the mass of SBRE improves the storage stability of SBRE, while WERs that exceed 1% weaken its storage stability. When the WERs reach 3% and 4%, the 5 d storage stability of prepared WSAEs will be beyond the limitation of specification. Incorporating WERs into SBRE negatively affects the workability of SBRE, and the workability of WSAEs is adversely influenced by the WERs content and the storage time. To ensure the construction, the WSAEs with 3% and 4% WERs should not be stored for more than 36 h and 48 h, respectively. The WERs effectively improve the high-temperature performance of SBRE residue, especially the 3% WERs. Besides, the WERs notably enhance the rheological property and thermal stability of SBRE residue. In contrast, the WER modifier produced by chemically modified method has a smaller adverse impact on the storage stability and workability of WSAE, and a larger enhancement on the high-temperature performance, rheological property and thermal stability of SBRE residue, which is thus recommended to modify SBRE.

Properties of the cement containing hybrid micro-fibers and polymer latex using the orthogonal test: A comparative study of freshwater and seawater curing conditions

The enhancement of cement properties through the integration of composite materials has become a prevailing topic, as it offers a solution to the limitations associated with single-material approaches. Our study aims to explore the synergistic potential of calcium carbonate whiskers (CWs), multi-wall carbon nanotubes (MWCMTs), and carboxylated styrene-butadiene rubber latex (XSBRL) in cement under seawater curing conditions, and freshwater conditions are added as the control group. The laboratory tests including fluidity, mechanical strength, and porosity were measured using the orthogonal test design method, and the weight matrix analysis method was used to determine the optimal mix proportion. The results showed that incorporating 5%, 10%, and 15% of XSBRL increased the fluidity by 17.87%, 48.55%, and 133.09%, respectively. On the contrary, the mechanical strength decreased by 8.33%, 10.85%, and 10.09% for seawater conditions at 28d, respectively, accompanied by an increase in porosity. CWs enhanced the mechanical strength by 7.69%, 10.92%, and 12.84%, respectively, and the pore structure was densified. MWCNTs first increased and then decreased the strength, and it may be due to the agglomerative effect. The optimal mix proportions were 3% CWs content, 0.2% MWCNTs, and 10% XSBRL for freshwater conditions, while 3% CWs, 0.3% MWCNTs, and 15% XSBRL for seawater conditions. X-ray diffusion (XRD) and scanning electron microscope (SEM) were used to characterize the phase composition, mineralogy, and microstructure. Results illustrated that CWs, MWCNTs, and XSBRL would not change the mineral phases of cement, and some Friedel’s salt and more ettringite were found under seawater conditions. The crack deflection, bridging effect, whisker breaking, and pull-out effect of CWs, the nucleating effect for hydration products and the crack control ability of MWCNTs, and the three-dimensional network structures of XSBRL were responsible for the considerable modification.

Effect of polymeric fiber coating on the mechanical performance, water absorption, and interfacial bond with cement-based matrices

The performance of sisal fibers in cement-based matrices is highly dependent on the interface efficiency between the fiber and the matrix. This behavior in turn is directly related to two main factors: the sisal fiber swelling tendency and fiber alkaline degradation. To enhance these properties and consequently the fiber–matrix adhesion, this study proposed the use of carboxylate styrene-butadiene rubber latex (XSBR) as a coating for sisal fibers. Different XSBR polymers and emulsions concentrations were adopted. The effects of this treatment on various properties of the fibers such as physical, chemical, and mechanical properties were studied. The physical properties of the modified fibers were investigated by means of scanning electron microscopy (SEM) and atomic force microscope (AFM) analyses. Also, changes in the moisture absorption capacity of the coated fibers were evaluated. To study the chemical influence of the polymer coating in the modified fibers, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) techniques were adopted. Direct tensile and pullout tests were also assessed in natural and coated sisal fibers, to mechanically evaluate the modification in terms of fiber strength and adherence, respectively. The results evidenced the formation of a new polymeric layer around the fiber, responsible to reduce the water absorption tendency of the natural fiber. The increase in the fiber–matrix adhesion obtained in the pullout evaluation was attributed to the rougher superficial aspect of the modified fibers and increased chemical interaction between the polymer and the cementitious matrix. Moreover, it was proven that the polymeric layer reduced the fiber's alkaline degradation susceptibility resulting in a more stable sisal fiber.

Modification and mechanism of polymer in high-performance concrete with full aeolian sand: An integrated macro-to-micro perspective

Producing high-performance concrete with full aeolian sand (FA-HPC) can achieve efficient utilization of desert resources to combat the shortage issue of aggregates. However, low water–cement ratio and high fine content result in a high risk of brittleness and durability in this concrete. Herein, polyacrylamide (PAM) and styrene-butadiene rubber latex (SBR) were incorporated into the FA-HPC to optimize its performance. Effects and mechanisms modifying the FA-HPC with polymers were compared and studied from macro-to-micro perspectives, with respect to workability, mechanical properties, durability, adsorption, and hydration. The results revealed a negative correlation with the PAM content (contrary to the SBR content) in fluidity and the content-dependent extension in setting time. For strength and shrinkage, the best performance was observed in the PAM-modified FA-HPC at 0.05% content presenting the substantial mitigation in brittleness. Moreover, regarding chloride resistance, SBR showed a more positive effect than PAM, with a 40.9% improvement at 10% content. From the micro-perspective observation, the retarding effect at early stages and acceleration during the late hydration process were verified by phase analysis. The polymer film and polymer bridge as well as the refined pore structure were the primary contributing factors to the performance improvement. Overall, compared to SBR modification, PAM modification with stronger adsorption capacity balances the comprehensive performance improvement of FA-HPC better at 0.05% content. Additionally, the specificity of the FA-HPC and the difference in modification behavior were discussed. This research allows the material-composition optimization of FA-HPC and further promotes the wide application of aeolian sand-based cementitious materials.

Biodegradable composite films based on mucilage from Opuntia ficus-indica (Cactaceae): Microstructural, functional and thermal properties

This study evaluated the feasibility of using cactus mucilage (CM) to elaborate biobased composite films blended with styrene-butadiene rubber latex (SBL). The CM was extracted and precipitated with ethanol (CMET) and isopropanol (CMIS). Mucilage-based films were formulated using three levels of mucilage (4, 6, and 8 wt%). The microstructure, thickness, moisture content, density, water contact angle, water vapor permeability, film solubility, thermal stability, and toughness of mucilage films blended with SBL (SBL/CMET and SBL/CMIS) were measured. The properties of mucilage-based films varied systematically, depending on the concentration of mucilage. The addition of SBL to CM film produces compatible, hydrophobic, flexible, and stiffer films with low moisture contents and good barrier properties. The mucilage film incorporated with 6 wt% CMET and CMIS reached the highest Young's modulus of 1512 ± 21 and 1988 ± 55 MPa, respectively. The DSC of produced films reveals that the Tg of SBL/CMIS is lower than that of SBL/CMIS. The synthesized films were structurally stable at high temperatures. The biodegradability of the composite films buried in the ground shows that the produced films are 100 % biodegradable after 40 days. Thus, CM blended with SBL can benefit specific applications, especially food packaging.

Hardened properties and microstructure change of sulphoaluminate cement modified with different doses of styrene-butadiene rubber latex

The composite of sulphoaluminate cement (SAC) and styrene-butadiene rubber (SBR) latex is expected to possess rapid strength development and adjustable elastic modulus, mainly used in rush repair engineering. This paper investigates the mechanical strength and drying shrinkage of SBR-SAC composites with different proportions. The change of pore structure, phase composition, and microtopography behind the composites was further revealed. Results indicate that, when the SBR/SAC ratio increases from 0/10 to 3/10, the flexural strength of the composite is increased by 343% and its compressive strength is increased by 14.7%, the drying shrinkage is almost not considered, below 0.1%. Besides, at the SBR/SAC ratio of 5/10, the composite loses brittleness, with no obvious peak value of load–displacement curves, and the drying shrinkage of composite at 23 d is 1.496%. This is because dehydrated polymer occupies the location of SAC hydrates, and the polymer film gradually and continuously covers the surface of the cement and becomes thickened. With the increasing SBR/SAC ratio, the continuous phase of composite probably transforms from inorganic cement phase to organic polymer phase.

Influence of polypropylene fiber with Styrene-Butadiene Rubber Latex bonding agent in prevention of early crack of concrete

We have fabricated the concrete reinforced polypropylene fiber with styrene-butadiene rubber latex bonding agent of concrete in different ratio. The prepared concrete employed with structural studies using FTIR and XRD spectra. An FTIR spectrum shows the important characteristics peaks of polypropylene fiber and styrene-butadiene rubber along with silica peaks. XRD pattern indicates that concrete crystal structure of three polymorphs such orthorhombic, triclinic and monoclinic phase. SEM image indicates that the above 10 wt % of polypropylene fiber causes small hairline cracks on its surface. It is found that the tensile strength increases with increase in different weight percentage of polypropylene fiber up to 10 wt %. This is may be due to the high compactness and reduction in porosity of the concrete block. It is also important to note that the water reduce admixture such as Polycarboxylates in required ratio’s significantly effects on capillary threshold by reducing 8-12 % of water results higher density of the concrete.

Development of Sustainable Concrete from Hypo Sludge Combined with Basalt Fibre and Latex

Cement production is a major source of carbon dioxide pollution. An environmentally friendly concrete needs to be developed in order to overcome the adverse environmental impacts of cement production and the continuing depletion of natural resources. Paper waste (hypo sludge) from the paper industry is becoming a challenge due to its extensive area requirements for disposal and continually increasing adverse environmental effects. To reduce paper waste and pollution, it might be beneficial to use it as hypo sludge in concrete mixes. In the present investigation, hypo sludge was used as a partial replacement in varied proportions (5, 10, 15, 20, 25, and 30%) of cement in concrete of M30 grade to be assessed. Styrene–butadiene rubber (SBR) latex and basalt fibre (BF) were added to hypo sludge concrete to improve its durability and post-cracking behaviour. From the test results, the optimum dosage of hypo sludge, basalt fibre, and SBR latex was found to be 15%, 0.3%, and 10%, respectively. From the mechanical properties testing compared with the control concrete, latex-added hypo sludge basalt fibre showed an increase in compressive strength by 17.08%, flexural strength by 14.55% and tensile strength by 14.29%. Microstructural results showed that SBR latex created greater consistency in the interaction of the concrete stages. Results of the tests indicate that the performance of the concrete in terms of its strength was improved by partially replacing the cement in the concrete with hypo sludge.

Preparation and performance optimization of eco-friendly geopolymers prepared from coarser lignite-based waste fly ash

Fly ash (FA) is generated in massive quantities by burning coal in power plants. The quality of the FA depends on the origin and type of coal. In developing countries, FA produced is relatively low quality and coarser. It does not meet the criteria to be used as a construction material and requires modifications. The waste lignite-based FA generated from a power plant was used in this investigation to produce geopolymer. The raw FA-based geopolymer was tested for normal consistency, initial setting time, fluidity, and compressive strength at different molarities of sodium hydroxide (SH, 8 to 14 M). The effect of different sodium silicate to NaOH (S/N) ratios (1 to 2.5) on the properties of geopolymer was also determined. However, maximum compressive strength of 14.1 MPa was achieved using S/N ratio of 2.5 and 12 M SH solution. Then different techniques were applied to increase the compressive strength of geopolymer, including high-temperature treatment, adding polymers and chemical admixtures. Heat curing the plain geopolymers in an oven at elevated temperatures, from 60 to 80 °C at 10 °C intervals for 2 h, yielded better compressive strengths. At 80 °C, the samples achieved a 71.2% increase in strength. Superplasticizers, i.e., polynaphthalene sulfonate and polycarboxylate ether-based, remained slightly effective for geopolymers. It was also corroborated that styrene-butadiene rubber latex (SBR) latex and polyvinyl alcohol (PVA) enhance fluidity and compressive strength of geopolymer. SBR and PVA can be used as superplasticizers and strength enhancers in geopolymer. Samples with SBR and PVA as polymeric admixtures provided 72.7% and 72.8% higher compressive strength than the control sample. Furthermore, grinding FA by ball and disc milling increased the fineness of FA. The ground FA also provided a 71.3% increase in compressive strength as compared sieved control geopolymer. This study provides a new approach for the high-value utilization of coarser lignite-based waste FA, and develops a new strategy for the performance improvement of low-quality FA-based geopolymers.

Effect of competitive adsorption between specialty admixtures and superplasticizer on structural build-up and hardened property of mortar phase of ultra-high-performance concrete

This study aims to enhance structural build-up of ultra-high-performance concrete (UHPC) without influencing the initial flowability, which is critical in repair applications (e.g., use of UHPC in thin bonded overlays for bridge deck rehabilitation). Specialty admixtures, such as a viscosity-modifying admixture (VMA), have been used to enhance the structural build-up at rest. However, the use of specialty admixtures can increase superplasticizer (SP) demand to maintain proper flowability; the synergistic effect of these admixtures on structural build-up is not well understood as the coupled admixture content can reverse the net effect on yield stress, viscosity, and thixotropy. In this study, VMAs including welan gum (WG), diutan gum (DG), and cellulose ether (CE) were used. Styrene-butadiene rubber (SBR) and acrylic ester (AE) latex polymers (LPs) that can enhance structural build-up and bond strength were also incorporated. The competitive adsorption between these specialty admixtures and SP and its effect on structural build-up, early-age hydration, compressive and pull-off strengths, porosity and entrapped air content of UHPC mortar (i.e., without fiber) were systematically investigated. Test results indicated that the incorporation of anionic WG and DG that exhibited high competitive adsorption with SP led to a 275%–450% enhancement in structural build-up despite the 55%–135% increase of SP demand. Such increase was limited to 130% when using CE, SBR, or AE that cannot effectively adsorb onto cement particles in the presence of SP. This was because the high competitive adsorption between specialty admixtures and SP strengthened the particle flocculation and promoted the cement hydration in the first hour; the latter resulted in 20%–40% enhancement in non-reversible component of structural build-up. Furthermore, the use of LP at low and moderate dosages secured high bond strength to normal strength mortar despite 8%–33% decrease in compressive strength given the increased capillary porosity. The use of VMAs increased the entrapped air and resulting 5%–15% lower compressive strength, while the bond strength was not influenced.

Effect of Evaporation Methods on Modified Emulsified Asphalt Residues from Rheological and Chemical Characteristics

Accurately evaluating and characterizing the performance of emulsified asphalt is the basis of its application. The rheological properties of modified emulsified asphalt residues and its material action mechanism were studied. To achieve this goal, styrene butadiene styrene (SBS)- and styrene butadiene rubber (SBR)-modified emulsified asphalt were prepared, and modified emulsified asphalt residues were prepared by the direct heating method (DHM) and two low-temperature evaporation methods (EN13074 and ASTM D7497-09). Then, the rheological properties and fatigue resistance of the modified emulsified asphalt residues were characterized through dynamic shear rheometry tests. Finally, Fourier transform infrared spectroscopy and elemental analysis were conducted to monitor the curing behavior of modified emulsified asphalt residues. The results indicated that the incorporation of SBS and SBR latex into emulsified asphalt significantly improved its viscoelastic properties, high-temperature properties, and fatigue life, and reduced its temperature sensitivity. Under different evaporation conditions, the unmodified emulsified asphalt residues and SBS-modified emulsified asphalt residues obtained by the ASTM D7497-09 evaporation method had the best rutting resistance and recovery percentage, followed by the emulsified asphalt residues obtained by EN13074 and DHM. However, the rutting resistance of SBR-modified emulsified asphalt residues was not greatly affected by the evaporation method. Though prepared with different evaporation methods, unmodified emulsified asphalt residues had similar fatigue life, and the fatigue life of modified emulsified asphalt residues were ranked as Nf (ASTM D7497-09) >Nf (EN13074) >Nf (DHM). The emulsified asphalt residues obtained by DHM and EN13074 still contain moisture, and it is recommended to use the ASTM D7497-09 evaporation method to obtain emulsified asphalt residues for performance evaluation.

Preparation of immiscible XSBR/PAM composite by constructing a leaf vein bionic nano-micro structure

The conflict between strength and toughness of plastic/rubber blends is still a great challenge in the world, especially for incompatible plastic/rubber blends. Here, we prepared carboxylated styrene-butadiene rubber latex (XSBR) and polyacrylamide (PAM) composites by a solution mixing method. FTIR and XPS results show a weak hydrogen bond between carboxyl groups of XSBR and amino groups of PAM, which is not enough to enhance the miscibility of XSBR and PAM. As a result, large parts of PAM precipitate to construct a macro continuous phase. A small part of PAM evolves from nanowires to a three-dimension nano network owing to the hydrogen bond inductive effect. Consequently, a leaf vein bionic nano-micro structure is proposed to interpret the great reinforcement effect in Young's modulus (112 times), tensile strength (almost 6 times) as compared to 5XSBR/5PAM with pure XSBR, which is almost equal to the mechanical properties of pure PAM. Meanwhile, the elongation at break and toughness of 5XSBR/5PAM is almost 1567% and 3370% of pure PAM, respectively. This may provide a new road to solve the conflict between strength and toughness.

Multi-objective design optimization of composite polymerized asphalt emulsions for cold patching of pavement potholes

Cold patching materials (CPMs) are commonly used for rapid pavement pothole repairing in cold and wet conditions. In this study, the composition of composite polymerized asphalt emulsions (CPAEs) as binders in CPMs was optimized using the response surface methodology (RSM). Three factors with three levels and four responses were considered. The RSM models had coefficients of determination of nearly 1.0, indicating a strong correlation between multiple factors and responses. The high and low true grade of CPAEs were dominated by the dosage of styrene-butadiene-styrene (SBS) and styrene-butadiene rubber (SBR) latex, while both the sieve residue and storage stability greatly depended on the emulsifier percentage. The optimal dosage of SBS, SBR and emulsifier in CPAEs was finally determined to be 7.32%, 7.78% and 3.44%, respectively, and validated by experiments. The modified CPMs prepared with the optimal CPAEs demonstrated superior resistance to permanent deformation, thermal cracking, moisture damage, the initial and cured strength compared to non-modified CPMs.

Stretchable PEDOT:PSS/Li-TFSI/XSB Composite Films for Electromagnetic Interference Shielding

Electromagnetic interference (EMI) shielding materials with stretchability are important for developing wearable and flexible appliances. Herein, lithium bis(trifloromethanesulfonyl)imide (Li-TFSI)-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and carboxylated styrene-butadiene rubber (XSB) latex are used to prepare stretchable EMI shielding composite films of 0.2 mm in thickness. In these films, the doped PEDOT:PSS nanoparticles form tenuous conductive pathways between the hexagonally packed latex particles, resulting in higher EMI shielding efficiency (EMI SE) compared with the films containing traditional dopant ethylene glycol. For the purpose of stretchable EMI shielding, the films containing 6 wt % PEDOT:PSS and 6 wt % Li-TFSI demonstrate EMI SE of 50 and 30 dB (12.4 GHz) at 0 and 100% strains, respectively, being the highest values among the reported shielding composites except for those using liquid metal as the filler. The investigation also provides a simple and environmentally friendly preparation method being highlighted for the development of lightweight stretchable EMI shielding materials for applications in flexible electronics in the near future.

Effect of addition of nanoclay and SBR latex on fly ash-slag geopolymer mortar

The influence of nanoclay and styrene-butadiene rubber (SBR) latex on the mechanical properties, durability, thermal resistance and microstructure of fly ash-slag geopolymer mortar is focused on in this research. The effect of nanoclay addition in different percentages of 2%, 4%, 6%, 8% and 10%, and the effect of SBR latex in different percentages of 5%, 10% and 15% are investigated. More in detail, the considered mechanical properties include compressive strength, split tensile strength and flexural strength; while the durability properties were water absorption, sorptivity, drying shrinkage, chloride permeability, acid resistance and sulphate resistance. The thermal resistance was assessed through weight loss and residual compressive strength after being exposed to temperatures of 200 °C, 400 °C, 600 °C and 800 °C. Furthermore, discrete polyvinyl alcohol (PVA) fibres in different percentages of 0.5%, 1.0% and 1.5% volume of mortar were added into the optimum mix aimed at the crack arresting properties and to modify the failure from brittle to ductile. The addition of nanoclay at an optimum dosage of 6% of binder resulted in better mechanical, thermal and durability properties. The addition of nanoclay and SBR latex resulted in lower water absorption and sorptivity, and the drying shrinkage and moisture movement also reached the specified limits of 0.09% and 0.06%. Moreover, the chloride permeability was reduced from moderate to low, and the resistance in acidic and sulphate environments was also enhanced. Even though the addition of SBR latex exhibited better mechanical properties and durability, the thermal resistance was lower after a temperature of 200 °C, due to the lower melting point of SBR. The strength degradation in geopolymer mortar at high temperatures was mainly due to dehydration and dehydroxylation leading to thermal incompatibility between geopolymer matrix and aggregates. The addition of PVA fibre has an increase in tensile and flexural strength at 1% fibre by volume. The SEM images show a more even microstructure with reduced microcracks in geopolymer mortar with nanoclay. FTIR analysis shows an improved degree of geopolymerisation by the addition of 6% nanoclay, and the addition of SBR latex has only physical interaction contributing to better mechanical properties and durability.

Effects of Styrene Butadiene rubber on the properties of Normal Concrete

This work titled “examining the effects of Styrene butadiene rubber latex on properties of normal concrete” is aimed at exploring the potential in the use of SBR latex in concrete to investigate how different properties of concrete can be improved. Styrene Butadiene Rubber Latex with brand name “Top Shield” was added by virtue of volume of cement in the concrete mix in percentages of 0, 5, 10, 15 and 20%. A total of 135 samples consisting of 45 pieces of 150mm*150mm*150mm cubes, 45 samples 100*100*500mm beams and 45 pieces of 200mm*10mm diameter cyl-inders were cast. A concrete mix design using ACI was used targeting a strength of 25N/mm2 and a mix ratio of 1:2.4:2.6 was used at a constant water cement ratio of 0.44 adopted. Samples were cured for 3, 7, 28 days. Samples were tested to investigate different properties of concrete test through slump, compressive strength, flexural strength, split tensile strength, water absorption, ultrasonic pulse velocity and scanning electron microscopy tests were conducted on the samples. Regression analysis of result was conducted using excel multiple regression tool and mathematical formulae were developed to help field workers and researchers forecast the degree of certain properties of interest and to determine how each variable affect the end result. Results showed positive improvement in all properties tested for. Preliminary quality control tests were carried out on the respective ingredients of concrete to determine their suitability with reference to ASTM Standard. The study recommended that further research should consider the use of a higher percentage of SBR latex to find the optimum compressive and tensile properties of the concrete.