Fourier Transform Infrared Spectroscopy Test Research Articles

Organo-Silica Membrane Prepared from TEOS-TEVS Modified with Organic-Acid Catalyst for Brackish Water Desalination

The sol gel process is one of the processes used in the manufacture of thin films on membranes because it can control the pore size in the resulting silica matrix. In addition, another way to build membrane size can be done by adding catalysts and precursors to be used. In this study, using a combination of tetraethyl ortho silicate (TEOS) and triethoxy vinyl silane (TEVS) precursors and citric acid as a catalyst to produce a silica matrix with mesoporous size so that it is suitable for application in the desalination process. The organo silica membrane was calcined at 350 ° C for 1 hour using the RTP calcination technique under vacuum, thus preventing the decomposition of carbon in the silica matrix. The membrane was dipcoated 4 times to obtain 4 layers. The FTIR (Fourier-transform Infrared Spectroscopy) test was carried out to see the functional groups on xerogel, namely silanol, siloxane and carbon. In addition, the performance of this membrane is carried out by desalination through pervaporation using 0.3% NaCl feed water with variations in feed air temperature, namely 25 ℃, 40 ℃ and 60 ℃. The resulting flux of air value increased with increasing feed water temperature, namely 6.1; 11.2; and 12.1 kg.m-2h-1 while the resulting salt rejection was 99.72; 99.64 and 99.23%. So that the organo silica membrane is suitable when applied to the desalination process through pervaporation.

Synergistic effect of salt ions and water‐soluble amphiphilic compounds of acidic crude oil on surface and interfacial tension

AbstractThis study investigated the effect of solubility of amphiphilic compounds of acidic crude oil in water on the surface and interfacial tension (IFT) with NaCl, MgCl2, CaCl2, and Na2SO4 salts. Accordingly, distilled water, along with the salts mentioned in zero ionic strength up to 2 mol were put in contact with crude oil to become saturated with amphiphilic compounds. The effects of these compounds were investigated on the properties of contact water by pH, total organic carbon (TOC), FTIR (Fourier transform infrared spectroscopy), water‐air surface tension (ST), and water‐n‐decane IFT tests. The results showed that some of the organic components of crude oil, especially acidic and basic compounds, are present or soluble in water, which have a significant effect on reducing the surface and IFT. The IFT reduction of water‐n‐decane was greater than the water‐air ST system. Also, the observations showed that for both NaCl and Na2SO4 salt water, with increasing ionic strength of water, there was an optimum salinity within the range of 0.1‐0.25 mol/L for both salts with the amount of surface and IFT minimized at this point. In the other two salts, this point was delayed upon elevation of ionic strength and was observed at high salinity. In this case, divalent cations reduce tension rate compared to monovalent cations. Due to solubility of acidic and basic groups in water, pH of salt water illustrates an acidic trend. Results of the FTIR test confirmed solubility of these compounds as well.

Effects of Gum Arabic-Coated Magnetite Nanoparticles on the Removal of Pb Ions from Aqueous Solutions

To study the removal of lead (Pb) ions from aqueous solutions, novel magnetite nanoparticles (NPs) of Ni0.31Mg0.15Ag0.04Fe2.5O4 were synthesized by coprecipitation synthesis using metal sulfates, and then coated with Gum Arabic (GA). The prepared NPs were analyzed using various spectroscopic and analytical methods, such as X-Ray diffraction analysis (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray spectroscopy (EDX), Fourier Transform Infra-Red spectroscopy (FT-IR), and Atomic Absorption Spectrophotometer (AAS). By using XRD analysis, the cubic inverse spinel structure of the prepared NPs was proven, showing average values of crystallite size, lattice constant, and density of 28.57nm, 8.32582Å, and 5.2890 g/cm3, respectively. FE-SEM analysis revealed the sphere-like shape of the nanoparticles with a measured crystallite size of 25.93nm. The existence of constituent elements was evidenced by EDX. FT-IR test proved the success of the coating process of magnetite NPs by the presence of the main characteristic absorption bands of GA in the FT-IR spectrum of GA-magnetite NPs. The adsorption of Pb ions by GA- magnetite NPs was shown by AAS analysis, where the concentration of Pb ions decreased from 25ppm to 6.6ppm, reaching 1.1ppm at the time of 25min. The porosity of the NPs and the carboxyl groups in GA played an important role in the process.

Rheological properties and microscopic mechanism of rock asphalt composite modified asphalts

In order to improve the low temperature performance of rock asphalt modified asphalt, this work presents a laboratory study to evaluate the rheological properties of rock asphalt composite modified asphalts considering aging effect. The mechanical properties of rock asphalt (RA)/styrene–butadienestyrene (SBS) composite modified asphalt (RA/SBSCMA) and RA/crumb rubber (CR) composite modified asphalt (RA/CRCMA) were assessed based on penetration, softening point and rotational viscosity tests. Experiments, including bending beam rheometer (BBR), dynamic shear rheometer (DSR), multiple stress creep and recovery (MSCR), fluorescent microscope (FM), and Fourier transform infrared spectroscopy (FTIR), were conducted to investigate the rheological properties and microstructure of rock asphalt composite modified asphalts, as well as the effect of polymer modification and aging on asphalts. Results demonstrated that the RA/CRCMA exhibited higher consistency, better deformation resistance and temperature sensitivity than RA/SBSCMA. The performance grade (PG) of RA/CRCMA indicates superior high- and low-temperature performance, of which the RA/CRCMA with 5% rock asphalt and 18% crumb rubber (5R/18C) performed the best. The RTFO and PAV aging reduced the frequency sensitivity, facilitated the internal network structure stability and improved the compatibility of the RA/SBSCMA with 5% rock asphalt and 2% SBS (5R/2S). The 5R/18C presented superior compatibility in different aging states. The MSCR test results showed that the RA/CRCMA exhibits excellent resistance to permanent deformation and superior elasticity and recovery deformation ability. The FM test revealed that grooves and protrusions existed on the surface of RA/CRCMA, and the spheroidal RA particles and the CR particles with irregular linear or mesh structure dispersed in the asphalt phase separately. The FTIR test results proved that the RA/SBSCMA was a primarily physical modification in nature, while the RA/CRCMA was a physical–chemical modification. The CR presented stronger inhibition on the formation of carbonyl and sulfoxide compounds than the SBS resulting in more excellent anti-aging performance of corresponding composite modified asphalt. It is recommended that the optimal percentages of additive materials were 5% for RA and 18% for CR.

Characterization and processability of post-consumer, double-recycled high impact polystyrene from disposable cups

The aim of this work is to characterize high impact polystyrene (HIPS) from disposable cups of different shapes and colors, these post-costumer cups, obtained from informal collectors were first crushed using a shredder, giving small particles of about 5 mm in characteristic size. A small portion of these granules was dedicated to the MFI (Melt Flow Index), DSC (Differential scanning calorimetry), FTIR (Fourier Transformation infrared spectroscopy) and TGA (Thermo-gravimetric analysis) test, while the rest was molded using a SINTESI injection press. Cylinder and nozzle temperatures were set at 200° C and 180° C, respectively, while the mold was held at 45° C. The dimensions of the molded samples were for tensile and bending samples. In order to simulate the recycling process as accurately as possible, the disposable cups underwent 2 successive grinding/injection cycles, and during each cycle the tensile, flexural strength, DSC, IRFT, TGA and MFI tests were performed to evaluate the evolution of the thermos-mechanical properties of the material. The present analysis proved the possibility of reintegrating the double-recycled material into the plastic industry, as its properties were only slightly affected: especially in the case of thin-walled packaging.

Chitosan-based hydrogel for treatment of temporomandibular joint arthritis

Abstract To produce polysaccharide-based hydrogels and cerium (Ce3+) doped hydroxyapatite plus chitosan and collagen to enable future applications in the treatment of joint degeneration. Hydrogel production and characterization were performed with Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and cytotoxicity testing with MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]. A final biomaterial composition was Kelcogel® Gelana (58%), chitosan (22.3%), Ce3+ doped hydroxyapatite (10.7%) and bovine collagen (9%), or selected aspect material gelatinous physical color with whitish color and can be injected. The biomaterial composition was proven in the FTIR and TGA, which also provided the maximum supported temperature. In the MTT assay, despite the reduction in viability of the experimental group compared to the control group, cell viability remained approximately 90%. In the FTIR and TGA tests, the material composition was proven. The material does not present cytotoxic behavior for the MTT test, being an alternative for the treatment of joint diseases.

Characterization of pepsin-soluble collagen extracted from gourami (Osphronemus goramy) scales.

Periodontal regeneration is the anticipated result of periodontal tissue therapy. Of the many scaffold materials utilized, collagen has been shown to possess characteristics that strongly promote the periodontal regeneration process. Gourami (Osphronemusgoramy) scales can be utilized as an alternative source of collagen due to their abundant availability, the absence of risk of zoonosis, and lack of religious strictures against their use. To analyze the characteristics of collagen extracted from gourami scales. A combination of scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and in vitro enzymatic biodegradation analysis were employed to determine pore sizes, constituent functional groups, and the degradation rate of collagen extractedfrom gourami scales. Collagen extracted from gourami scales demonstrated an average porosity of 13.779 μm. The FTIR test results indicated Amide A, Amide B, Amide I, Amide II, and Amide III peaks. The degradation rate of extracted collagen from gourami scales was 92.00 ± 0.8165% on the first day, 95.75 ± 1.70783% on the third day and 100% on the seventh day. The pore sizes ofcollagen extracted from gouramy scalesare suitable for use as scaffold. FTIR analysis indicated that this collagen possessed a triple helix structure. Collagen extracted from gourami scales was completely degraded within seven days when treated with 0.6 g/mL collagenase solution.

Effect of water diffusion and thermal coupling condition on SBS modified asphalts’ surface micro properties

Moisture damage is a particular concern for asphalt aging during the service life of asphalt mixture and pavement. At present, the microscopic research of the surface morphology, mechanical property and chemical composition of SBS modified asphalts under the water diffusion and thermal coupling condition is lacking. In order to characterize the effect of water diffusion-thermal condition on surface micro properties and moisture sensitivity of SBS modified asphalts, atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) were used in this paper. Both SBS modified and Pen70 asphalts showed the similar evolution under the water diffusion-thermal coupling condition from AFM images. FTIR tests confirmed that the polar compounds increased and SBS polymer decreased in SBS modified asphalts. Meanwhile, the increasing exposure temperature would accelerate the evolution of the chemical composition and surface structure. What’s more, combined with AFM and FTIR tests results, it was found that the formation of microstructure and the micromechanical properties were closely related to the chemical functional group indexes. The ratio of modulus between wet-conditioned sample and dry sample was proposed to evaluate the SBS modified asphalts’ moisture-thermal sensitivity. The interactions between polar compounds with water molecules and the reduction of SBS polymers were collectively responsible for the arise of the surface modulus and moisture-thermal sensitivity of SBS modified asphalt. In addition, the diffusion of water in asphalt films followed Fick’s second law. It was found that the water molecules diffused slower in SBS modified asphalt, which might be associated with the interaction between water molecules and SBS modifier.

Formulation of a new warm-mix recycling agent and its rejuvenating effect on aged asphalt

Warm-mix recycling asphalt mixture has remarkable environmental and economic benefits. In this study, a new warm-mix recycling agent (WR) was developed by using base oil (80%), surfactant (9.5%), plasticizer (8.0%) and antiaging agent (2.5%) based on uniform design method. Experimental tests including penetration, softening point, ductility, elastic recovery, dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR), linear amplitude sweep (LAS), rotational viscosity as well as Fourier transform infrared spectroscopy (FTIR) test were conducted to evaluate the properties of aged binders incorporating the WR and other two commercial rejuvenators, i.e. an emulsified rejuvenator (ER) and a resinous rejuvenator (RR). Additionally, the workability and cost of reclaimed asphalt binders were analyzed. Results indicate that the WR is able to rejuvenate conventional physical properties of aged asphalt. Reclaimed asphalt containing WR shows the best low-temperature performance and longest fatigue life than that containing other two commercial rejuvenators. With regard to high-temperature performance, reclaimed asphalt incorporating WR compares favorably with that incorporating ER. The results from FTIR test demonstrated that physical interaction dominated the rejuvenation of aged asphalt after adding the WR. WR can significantly replenish the volatiles in aged asphalt, and restore its components’ proportion that resembles the virgin asphalt. In comparison with ER and RR, WR exhibits a lower increased cost and the excellent capability of reducing mixing and compaction temperature.

Poly-(fluoro isopropyl butyl methacrylate)/graphene-based sensitive oxygen nanocomposite: Electrical measurements and chemical interaction in variable pressure

An innovative pressure sensitive nanocomposite based on reduced graphene oxide and pressure sensitive paints was created to facilitate the application and ensure uniform coverage on complex surfaces. Three nanocomposite compositions of 4 mg/mL, 8 mg/mL and 12 mg/mL were produced by ultrasonication. Morphological and structural analyses of the material were carried out by Scanning electron microscope (SEM-FEG), Fourier-transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS). Conductivity and sensitivity measurements were investigated for impedance. SEM-FEG results show that rGO interacts with titanium dioxide (TiO2). This interacting is different for each concentration and interferes in the sensitivity to pressure. An FT-IR test indicated a possible mechanism of this sensitivity: induction and resonance interactions between polymer and rGO. It is influenced by oxygen binding with metalloporphyrin molecules. Results of XPS confirm the chemical interaction by FT-IR and migration of TiO2 by SEM. XPS measurement also indicates interactions between metalloporphyrin and rGO This generated an increase in active platinum sites. The carbon reinforcement generates an increase in conductivity, and it was important to realize the sensibility of nanocomposites. Composition of 12 mg/mL presented the highest conductivity and sensitivity.

Early effect of graphene oxide-carboxymethyl chitosan hydrogel loaded with interleukin 4 and bone morphogenetic protein 2 on bone immunity and repair

To investigate the effect of graphene oxide (GO)-carboxymethyl chitosan (CMC) hydrogel loaded with interleukin 4 (IL-4) and bone morphogenetic protein 2 (BMP-2) on macrophages M2 type differentiation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). GO solution was mixed with CMC, then the phosphate buffered saline (PBS), IL-4, BMP-2, or IL-4+BMP-2 were added to prepare different GO-CMC hydrogel scaffolds with or without different cytokines under crosslinking agents. The characteristics of pure GO-CMC hydrogel were characterized by gross observation, scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR), and the CMC hydrogel was used as control. The sustained release of GO-CMC hydrogels with different cytokines was also tested. Macrophages were isolated and cultured from female Sprague Dawley rats aged 4-5 weeks, and then cultured with GO-CMC hydrogels with and without different cytokines, respectively. CD206 immunofluorescence staining was used to detect the differentiation of macrophages after 24 hours. The 3rd generation of rats BMSCs were cultured with GO-CMC hydrogels with and without different cytokines respectively for osteogenic induction. The early osteogenesis was observed by alkaline phosphatase (ALP) staining after 10 days, and the late osteogenesis was observed by alizarin red staining after 21 days. Generally, GO-CMC hydrogel was brown and translucent. SEM showed that the pore diameter and wall thickness of GO-CMC hydrogel were similar to that of CMC hydrogel, but the inner wall roughness increased. FTIR test showed that CMC polymerized to form hydrogel. In vitro, the sustained release experiments showed that the properties of GO-CMC hydrogels loaded with different cytokines were similar. CD206 immunofluorescence detection showed that GO-CMC hydrogels could induce macrophages differentiation into M2-type. ALP and alizarin red staining showed that GO-CMC hydrogels could induce BMSCs osteogenic differentiation, in which GO-CMC hydrogel loaded with IL-4+BMP-2 showed the most significant effect ( P<0.05). The GO-CMC hydrogel loaded with IL-4 and BMP-2 can induce macrophages differentiation into M2-type and enhance the ability of BMSCs with osteogenic differentiation in vitro, which provide a new strategy for bone defect repair and immune regulation.

Effect of silicon-containing nitrogen and phosphorus flame-retardant system on the mechanical properties and thermal and flame-retardant behaviors of corrugated cardboard

In this paper, a new designed silicon-containing nitrogen and phosphorus flame-retardant system containing ammonium polyphosphate, modified molecular sieve and methylcellulose was used to prepare the flame-retardant corrugated cardboards (FRCCB). The samples before and after treatment were tested for combustion and thermal stability using vertical burning test (VBT), limiting oxygen index (LOI), cone calorimetric test (CCT) and thermogravimetry (TG). To further analyze the flame-retardant properties of the flame-retardant system, the microstructure, surface elements and functional groups of the materials were characterized by the scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the samples were tested to analyze the effect of flame-retardant treatment on the strength. The VBT and LOI tests showed that the samples after the flame-retardant treatment were able to self-extinguish after ignition, achieving the flame-retardant B-1 grade. The CCT tests showed that the total heat release of treated samples was reduced by 49.90%, and the total smoke production was decreased by 27.64%. TG tests showed that the thermal decomposition temperature of FRCCB decreased but the residual carbon content increased largely. FTIR tests showed that the functional group changed at different temperatures. After flame-retardant treatment, a dense carbon layer was formed on the surface of the treated sample, including N, P, Si and Cu, measured by SEM and EDS. Combining with various characterization methods, the flame-retardant system can retard flame by releasing nonflammable gases, forming covers and catalyzing char formation.

Characterization of Natural Cellulose Fiber from the Barks of Vachellia farnesiana

ABSTRACT The need for environmental friendly materials have stimulated researchers to carry out works in natural fibers, which are substitute for human-made synthetic fibers in many lightweight medium load applications. In the present work, Vachellia farnesiana fiber was selected as a natural fiber. The obtained Vachellia farnesiana fibers were characterized for physical and chemical properties, Thermo Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and, tensile strength. Scanning Electron Microscope (SEM) was used to capture its morphological characteristics. The outcome of the chemical analysis showed the weight percentage of ɑ-cellulose, hemicellulose, moisture content, wax, density and the same was confirmed by the output of the FTIR test. XRD test results showed that Vachellia farnesiana fiber had a crystallinity index of 13% and a crystal size of 31.89 nm. Thermal analysis showed a char residue of 28.71%.

Sr-doped bioactive glasses for biological applications

In the present study, sol–gel derived BGs based on 60% SiO2-(36-x) CaO-4P2O5-x SrO (where x = 2, 4, 6 and 8 mol%) system were synthesized. The effect of Sr on bioactivity and proliferation of G292 cells was investigated. X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were utilized to study the obtained phases, HA morphology, and its functional groups, respectively. The XRD and FTIR tests showed that the rate of hydroxyapatite formation on sample 2S was higher than that of other samples. The 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after one day immersion in SBF, showed that the viability of the samples containing 6 mol% Sr (6S) increases by increasing immersion time, while the sample containing 8 mol% Sr (8S) showed a decrease in bioactivity in osteoblast G292 cells proliferation. According to the results 6S BG specimen with 6 mol% SrO exhibited appropriate bioactivity and cell proliferation.

Experimental Study on the Micromorphology and Strength Formation Mechanism of Epoxy Asphalt During the Curing Reaction

The micromorphological changes and the strength formation mechanism of the curing of epoxy asphalt, which is mostly used for steel bridge deck pavements, were investigated. A tensile test was used to analyze the mechanical properties of epoxy asphalt, and Fourier transform infrared spectroscopy (FTIR) was used to determine the change in the epoxy peak area. Laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM) were used to observe two-dimensional and three-dimensional micromorphological changes, respectively, during the curing reaction of epoxy asphalt. The results of the tensile and FTIR tests on epoxy asphalt showed that the tensile strength and epoxy conversion rate both increased with the curing time and exhibited similar trends, indicating that the network formed by the crosslinking and polymerization of epoxy groups causes the increased strength of epoxy asphalt. The curing degree of epoxy asphalt during the curing reaction can be indirectly evaluated from the conversion rate of epoxy groups. The asphalt tended to evenly be dispersed in the continuous phase of the epoxy resin during the formation of the epoxy resin network, and the network structure increased the deformation of the epoxy resin. The epoxy asphalt curing reaction process was classified into three stages based on the degree of curing.

Effect of natural antioxidants on oxidation stability of jackfruit seed oil (Artocarpus heterophyllus) biodiesel

ABSTRACTAntioxidant addition to biodiesel promotes improvement in oxidation stability, which leads to its storage for a longer period. The induction period of biodiesel obtained from jackfruit seed oil (Artocarpus heterophyllus) was evaluated to be 1.49 h, which was less than the standards. The present work examines the characterization and impact of natural antioxidants in addition to biodiesel. The natural antioxidants selected in the present study involve Cumin seed, Coriander, Garlic, Star anise, and Gooseberry added with jackfruit seed oil biodiesel (JSOBD). The characterization of the chosen natural antioxidants with DPPH (2, 2-diphenyl-1-picrylhydrazyl) scavenging assay using UV Spectrophotometer, presence of functional compounds using FTIR (Fourier Transform Infrared Spectroscopy), total phenolic content estimation by Folin Ciocalteu method (Gallic acid equivalence method), Induction period using Rancimat method has been carried out in the present study. The maximum scavenging effect in terms of % was found to be 68, 71, 78, 74 and 82 for Cumin seed, Coriander, Garlic, Star anise, and Gooseberry respectively. FTIR test confirms the presence of OH, carboxylic acid group and phenolic functional compounds in the ethanol extracts responsible for antioxidant characteristics. The maximum total phenolic content value of about 135 mg/g and a minimum value of about 86 mg/g was observed for Gooseberry and Cumin seed respectively. The induction period (hours) assessed to measure the oxidation stability employing the Rancimat approach was maximum for Gooseberry with a value of 9.56 h at 2500 ppm. Thus among the selected natural antioxidants, Gooseberry was found to be effective in exhibiting maximum antioxidant characteristics.

The effect of polybutadiene rubber (PBR) on chemical and rheological properties of the binder including RAP

This research investigates the effect of polybutadiene rubber (PBR) on chemical and rheological properties of asphalt binder with 15, 30 and 50% RAP content. SARA-separation and Fourier Transform Infrared-spectroscopy (FTIR) were used to assess the chemical properties of the samples. Bending Beam Rheometer (BBR) test was applied to evaluate low-temperature performance and Dynamic Shear Rheometer (DSR) and Multiple Stress Creep Recovery (MSCR) tests were carried out to investigate high temperature performance of specimens. Results showed that the addition of PBR altered the chemical properties of the binder and led to an improvement of the rutting resistance of specimens. Despite the very low glass transition temperature of PBR, it deteriorated the low-temperature performance of samples. Moreover, some strong correlations between chemical characters (SARA – fractionation and FTIR tests) and physical parameters of the binder were found.

Effect of catalytic-reactive rejuvenator on structure and properties of aged SBS modified asphalt binders

During aging process of styrene–butadienestyrene copolymer (SBS) modified asphalt (SBSMA), hardening of asphalt matrix combined with degradation of SBS modifier simultaneously occurs. A novel catalytic-reactive rejuvenator containing epoxidized soybean oil (ESO) and triphenyl phosphine (TPP) was applied to repair damaged network structure of SBS. In this study, the effects of different blending time and different content of catalytic-reactive rejuvenator on the pressure aging vessel (PAV) aged SBSMA were investigated. The physical and rheological characteristics of unaged SBSMA, aged SBSMA and rejuvenated SBSMA were investigated, and chemical structure of binders were analyzed by Fourier transform infrared spectroscopy (FTIR) to assess the rejuvenation effect. The results illustrate that based on physical properties and the data reflected by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) parameters, 30 min blending is the optimal preparation condition compared with other blending time (15 min, 1 h and 2 h). With the addition of catalyst and increase of its content, the low-temperature flexibility performance of asphalt is improved according to the ductility and BBR tests, and the softening points and the viscoelastic properties obtained in DSR test are improved first and then decline gradually as a result of the multiple effects of catalyst on repairing SBS structure and softening binder. Based on the results of FTIR test, the increasing of –OH peak and the generating of C–O–C peak indicate that the epoxy group of ESO can be opened by catalyst and then polymerizes with aged SBS chains.

Short- and Long-Term Epoxy Modification of Bitumen: Modification Kinetics, Rheological Properties, and Microstructure.

Aiming to gain knowledge in the epoxy-bitumen modification mechanisms, this work explores the effects that epoxy concentration and ambient curing exert on the physico-chemistry and thermo-rheological properties of epoxy-modified binders. Process rheokinetics of epoxy-bitumen blends indicates that binder short-term modification (i.e., during processing) is accelerated by epoxy concentration. Furthermore, a synergistic effect of epoxy concentration and ambient curing is found during long-term modification (i.e., during curing at ambient conditions). As a result, viscous and viscoelastic rheological properties of binders are enhanced at medium/high in-service temperatures, at least, after one month of curing. FTIR (Fourier Transform Infrared spectroscopy) tests and SARAs (Saturates, Aromatics, Resins and Asphaltenes) analysis confirm the existence of esterification/etherification reactions between epoxy oxirane groups and the carbonyl groups available in aromatic and resin molecules. Thus, the new high molecular weight compounds increase the asphaltenic fraction of modified bitumen. Likewise, nonreversing heat flow curves obtained by modulated calorimetry corroborate the formation of such highly structured domains responsible for the final binder performance.

Use of Sulfur-Free Lignin as a novel soil additive: A multi-scale experimental investigation

With the rapid process of urbanization, more and more infrastructures are inevitably built on problematic soils, which require improvement and reinforcement. In this study, a novel material Sulfur-Free Lignin (SFL), which is a by-product of bioethanol industry, was used to improve the soil's geotechnical behavior as a sustainable, non-toxic and eco-friendly stabilizer. To systematically investigate the geotechnical properties of SFL-stabilized soil, the natural soil was modified by adding five different contents (3, 7, 10, 12 and 15%) and then a series of geotechnical experiments including Unconfined Compressive Strength (UCS), Atterberg limits tests, electrical resistivity and pH were carried out after 1, 7, 28, 60-days curing. In addition, to investigate the stabilization mechanism, the mineral composition, function group and microstructure characteristic were also studied through X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Mercury Intrusion Porosity (MIP) and Scanning Electron Microscopy (SEM) tests. The test results demonstrate that with increasing SFL content, the electrical resistivity gradually decreases, on the contrary, the Atterberg limits show a slight increase. However, the pH values are unchanged indicating the SFL would not lead to pH contamination risk. The 10% SFL-stabilized soil after 60 days of curing shows the greatest strength, which increases about 600% compared to the natural soil. Furthermore, the relationship between stiffness and UCS is generally proportional. According to the results of MIP and SEM, the strength improvement can be attributed to a smaller total volume of pores, reduction in the mean size of the pores and stronger bonds formed by SFL between isolated grains. The results of XRD and FTIR tests reveal there is no new mineral nor function group generated after adding SFL. Above all, the natural soil stabilized by SFL shows a satisfactory engineering performance and it would be a win-win solution to utilize SFL as a soil stabilizer for soil improvement in civil engineering and for waste elimination in bioethanol industry.