Resin Solution Research Articles

Fabrication of C/C‐SiC composites using high‐char‐yield resin

AbstractCarbon fiber reinforced ceramic matrix composites (C/C‐SiC composites) were fabricated using a type of high‐char‐yield phenolic resin with the char yield of 81.17 wt.%. Firstly, the fabric prepreg was prepared by spreading the phenolic resin solution onto the two dimensional carbon fiber plain weave fabric and dried consequently. Afterward, the resin was cured and then the carbon fiber reinforced polymer (CFRP) was pyrolyzed to get amorphous carbon. Finally, C/C‐SiC composites were obtained through liquid silicon infiltration (LSI) process. SEM micrographs showed that the Si/SiC area was homogeneously dispersed in the matrix, and during the siliconization process, a layer of SiC was formed along the surface of carbon fibers or carbon matrix. The fiber volume of CFRP was about 40 vol.%, which was much lower than other studies. XRD result indicated that only β‐SiC type was formed. The result of X‐ray computed tomography clearly showed the structure changes before and after the melt infiltration process. Mechanical property test showed that the composites had fracture strength of 186 ± 23 MPa, and a flexural modulus of 106 ± 8 GPa.

Facile fabrication of superhydrophobic fly ash-coated mesh for oil-water separation

The pollution of water by oil is a global challenge. In this study, the design and fabrication of a superhydrophobic stainless steel mesh are reported. This was achieved through a sample “glue + fly ash” fabrication method. The fly ash was first modified by a stearic acid solution impregnation method. After the modification, the fly ash was then bonded to the surface of a stainless-steel mesh by an epoxy resin solution to obtain the superhydrophobic mesh. The introduction to the modified fly ash endows the mesh with excellent corrosion resistance and superhydrophobicity when compared with the original mesh. The as-prepared mesh could separate various oil and organic solvents from water with a separation efficiency exceeding 98%. Interestingly, the oil separation capacity of the as-prepared mesh still kept a high value after 30 cycles of reuse. The simplicity, eco-friendliness and low cost of this method turn it into a practical and realistic approach to the large-scale fabrication of superhydrophobic surfaces. These properties make the as-prepared mesh an ideal candidate for actual oily wastewater treatment.

Fabrication, microstructure and ablation resistance of C/C–SiC composites, by using a novel precursor of SiC

A novel precursor of SiC prepared by mixing boron phenolic resin and hydrolytic solution of tetraethyl orthosilicate was employed to fabricate the ablation-resistant C/C–SiC composites. The pyrolysis behaviors of precursor and the ablation properties of prepared composites were discussed. Results show that during the pyrolyzation process of the precursor, the carbon phase was evenly surrounded by the silica phase, benefitting the occurrence of the carbothermal reaction. The precursor was totally transformed into SiC with the carbon left (7.77–8.11 wt%) after heating at 1600 °C. Due to the unique surrounded structure between the carbon and silica phases, part of the residual carbon was encircled by the generated SiC ceramics. During ablation, the carbon nucleus played a positive role in enhancing ablation resistance of composites by hindering the flow of molten silica. Compared with the composites employed polycarbosilane as precursor, this prepared C/C–SiC composites exhibited a decent anti-ablation performance.

Chemically stable superhydrophobic polyurethane sponge coated with ZnO/epoxy resin coating for effective oil/water separation

In this study, a superhydrophobic polyurethane sponge was prepared by a simple immersion method. The strategy was based on coating a ZnO/epoxy resin solution onto the skeleton of a porous polyurethane sponge, followed by reacting it with a mixture of stearic acid/acetic acid/ethanol solution. The prepared superhydrophobic polyurethane sponge with a contact angle of 156 ± 3° can selectively separate mixtures of water and various oily solvents. The separation efficiencies of the superhydrophobic polyurethane sponge for a variety of oil/water mixtures were all above 98 %. Moreover, the prepared superhydrophobic polyurethane sponge had superior reusability and maintained a separation efficiency of more than 97 % after ten oil/water separation cycles, and it was chemically stable from pH 1–11. This superhydrophobic polyurethane sponge may offer a new oil/water separation strategy due to its excellent separation efficiency, reusability, and chemical stability.

Adsorption of Anthocyanins by Cation and Anion Exchange Resins with Aromatic and Aliphatic Polymer Matrices.

This study examines the mechanisms of adsorption of anthocyanins from model aqueous solutions at pH values of 3, 6, and 9 by ion-exchange resins making the main component of heterogeneous ion-exchange membranes. This is the first report demonstrating that the pH of the internal solution of a KU-2-8 aromatic cation-exchange resin is 2-3 units lower than the pH of the external bathing anthocyanin-containing solution, and the pH of the internal solution of some anion-exchange resins with an aromatic (AV-17-8, AV-17-2P) or aliphatic (EDE-10P) matrix is 2–4 units higher than the pH of the external solution. This pH shift is caused by the Donnan exclusion of hydroxyl ions (in the KU-2-8 resin) or protons (in the AV-17-8, AV-17-2P, and EDE-10P resins). The most significant pH shift is observed for the EDE-10P resin, which has the highest ion-exchange capacity causing the highest Donnan exclusion. Due to the pH shift, the electric charge of anthocyanin inside an ion-exchange resin differs from its charge in the external solution. At pH 6, the external solution contains uncharged anthocyanin molecules. However, in the AV-17-8 and AV-17-2P resins, the anthocyanins are present as singly charged anions, while in the EDE-10P resin, they are in the form of doubly charged anions. Due to the electrostatic interactions of these anions with the positively charged fixed groups of anion-exchange resins, the adsorption capacities of AV-17-8, AV-17-2P, and EDE-10P were higher than expected. It was established that the electrostatic interactions of anthocyanins with the charged fixed groups increase the adsorption capacity of the aromatic resin by a factor of 1.8–2.5 compared to the adsorption caused by the π–π (stacking) interactions. These results provide new insights into the fouling mechanism of ion-exchange materials by polyphenols; they can help develop strategies for membrane cleaning and for extracting anthocyanins from juices and wine using ion-exchange resins and membranes.

Organic Aerogels Based on Epoxy Resins: Synthesis and Properties

The aim of this work was to develop methods for the synthesis of organic aerogels based on epoxy resins and to investigate their properties. Aerogels based on DGEBA-epoxy resin were obtained by CO2-supercritical drying of gel samples prepared from acetone solutions of epoxy resin with different amount of catalyst and solvents. As a result, aerogels of different density were obtained; the dependence of density on the solvent content in the samples was revealed. The aerogels were characterized by infrared spectroscopy to define the degree of conversion of the epoxy groups, by SEM to confirm nanoscale morphology of aerogels, as well as by the BET method to determine the specific surface area of the samples and its dependence on the catalyst content and curing conditions.

Commiphora myrrha stimulates insulin secretion from mouse and human islets of Langerhans

Ethnopharmacological relevanceTraditionally plant-based remedies such as Commiphora myrrha (CM) have been used as an ayurvedic medicine to treat diabetes mellitus in some region of Arabia and Africa. Previous reports have shown that CM reduced blood glucose levels and increased insulin concentrations in animal models of diabetes in vivo. However, the exact mechanisms by which CM improved glycemic control in these animals are not fully understood. We hypothesized that CM may have a direct insulinotropic activity on β-cells to increase insulin secretion. Aim of the studyThe direct effects of CM were investigated using MIN6 β-cells and isolated mouse and human islets in static and perifusion insulin secretion experiments. Isolated mouse and human islets were used to investigate the rate and pattern of CM-induced insulin secretion. Materials and methodsThe effect of CM on insulin secretion was assessed by static and perifusion experiments using MIN6 cells, a mouse-derived β-cell line, and primary mouse and human islets. The effects of CM on cell viability and membrane integrity of MIN6 cells and mouse islets were assessed using an ATP viability assay and a trypan blue exclusion test. The mRNA expression profiles of preproinsulin and Pdx1, a major β-cell transcription factor, were determined by quantitative RT-PCR following chronic exposure to CM. ResultsExposing MIN6 cells to a CM resin solution (0.5–10 mg/ml) caused a concentration-dependent increase in insulin secretion in a static setting. Similarly, incubating mouse islets to CM (0.1–10 mg/ml) resulted in stimulation of insulin secretion in a concentration-dependent manner. CM concentrations at ≤ 2 mg/ml were not associated with reduction in cell viability nor with reduction in cell membrane integrity. However, higher concentrations of CM were accompanied with marked uptake of trypan blue dye and cell death. In a perifusion setting, CM (2 mg/ml) caused rapid and reversible increases in insulin secretion from both mouse and human islets at both sub-stimulatory and stimulatory glucose levels. The stimulatory effect of CM on insulin secretion did not change the total insulin content of β-cells nor the mRNA expression of preproinsulin and Pdx1. ConclusionsThese data indicate that aqueous CM resin solution has a direct stimulatory effect on β-cells without compromising plasma membrane integrity. CM stimulates insulin secretion from MIN6 cells, a mouse-derived β-cell line, and isolated primary mouse and human islets in vitro at both sub-stimulatory and stimulatory glucose concentrations. The mechanism by which CM may induce insulin secretion is most likely due to a stimulation of insulin granules release rather than insulin synthesis.

Optimization of Materials Composition and UV-VIS Light Wavelength Towards Curing Time Performance on Development of Tissue Engineering Scaffold

VAT photopolymerization 3D printing is a process that solidified a vat of liquid photopolymer resin solution into desired products in the presence of UV light. Achieving an optimal property with shorter curing time is an ultimate goal when using functional or special resins. In this study, the effect of wavelength with different compositions of UHT resin mixed PEG solution is studied. Different sources of light were identified, which is UV-A with a wavelength of 365 nm and VIS with a wavelength greater than 420 nm. The PEGconcentrations were varied at 40%, 50%, and 60%. While UHT concentration ratio added into solution was 30%, 50%, and 70%. It has been observed that the optimum curing under UV and VIS wavelength were 9.55 minutes and 17.48 minutes respectively. The feasible range to optimize results of curing time, PEG 48%and UHT 41% with the result 8.6 minutes for the UV-A. Meanwhile, for VISwavelength, PEG 49% and UHT 64% with the result 16 minutes. The success of this study will lead to further innovation on UV-VIS light source in 3D printing in terms of energy efficiency, safety, and cost as well as further evaluation of the performance with respect to the mechanical properties of tissue engineering scaffold.

Morphology, thermal, and mechanical properties of κ-aluminum oxide/CTBN/epoxy nanocomposites

In this study, novel κ-aluminum oxide (κ-Al2O3) nanosheets and carboxyl-terminated butadiene-acrylonitrile (CTBN) liquid rubber were homogeneously mixed in epoxy resin solution by a homogenizer with a high shear force. Then, κ-Al2O3/CTBN/epoxy nanocomposites were fabricated by a stepwise thermal curing process. The dispersion of κ-Al2O3 nanosheets in the CTBN/epoxy blend was examined by a transmission electron microscopy. The effects of κ-Al2O3 nanosheets on the thermal, tensile, and morphological properties of κ-Al2O3/CTBN/epoxy nanocomposites were systematically studied. Results indicated that κ-Al2O3 nanosheets can effectively increase both the tensile modulus and elongation at break of κ-Al2O3/CTBN/epoxy nanocomposites. Meanwhile, the optimized properties were observed when 5 phr of κ-Al2O3 nanosheets were added. The thermal stability (Td5%) and glass transition temperatures (Tg) of κ-Al2O3/CTBN/epoxy nanocomposites were also higher than those of CTBN/epoxy blend. According to experimental results, the κ-Al2O3 nanosheets can be considered as suitable and effective as a reinforcing material for epoxy resin or other polymers.

Nanoclay-modified microcapsules as a latent curing agent in epoxy

Application of microcapsules as a latent curing agent has been attracted a lot of attention, recently. However, in this type of latent curing agent, the leakage of core material from the microcapsule shell is a major problem. In this study, nanoclay particles were used as a promising approach to prevent the flow out of core materials from the microcapsules’ shell. To this end, nanoclay particles were dispersed in a solution of solid epoxy resin in acetone under sonication process and then were used for microencapsulation of 1-methylimidazole (1-MI) via solvent evaporation method. Scanning electron microscopy was used to study the shape and morphology of the prepared microcapsules. 1-MI content of microcapsules was measured using thermal gravimetry analysis. Curing behavior of microcapsule-embedded epoxy resin was investigated using differential scanning calorimetry and rheometry measurement. In comparison with the neat microcapsules, nanocomposite microcapsules showed better barrier property and longer gel time at high temperature, which can be attributed to the presence of platelet nanoclay particles throughout the microcapsules’ shell.

Electrochemical Destruction of per- and Polyfluoroalkyl Substances (PFAS) in Complex Solution Matrices

Per- and Polyfluoroalkyl substances (PFAS) are a group of manmade chemicals which are persistent in the environment and have shown to be toxic to human health. They have accumulated in drinking water, groundwater, and wastewater around the globe for over six decades. Although the production of some chain lengths has ceased, remediation is critical. Current remediation techniques include adsorbents such as granular activated carbon (GAC) and Ion exchange (IX) columns. GAC is merely used to adsorb the PFAS, but struggles with capturing shorter chains and requires regeneration with incineration.1 IX has shown improvement in its ability to capture all PFAS chain lengths, and can be regenerated with a solution comprised of a salt or base and an alcohol.1 This regenerate solution desorbs all of the PFAS from the resin into a smaller concentrated solution of roughly a few hundred gallons. This solution is typically comprised of PFAS in the parts per million (ppm) range.2 These concentrated PFAS solutions can lead to further contamination of the environment through discharge of landfill leachate to wastewater treatment plants from landfill disposal. Due to the high salinity, low volume, and high concentration of PFAS in IX regenerate solutions, electrochemical oxidation is a promising treatment technology to destroy the PFAS and remove the chance of future human exposure.This study employs a boron-doped diamond (BDD) on niobium (Nb) electrode stack to investigate the role that current density has in the electrochemical destruction of PFAS in a complex solution matrix. The electrode stack was comprised of two anode plates sandwiched in between three cathode plates. This entire stack was then placed into a constantly stirred reactor comprised of 750 ml of solution. A constant current density of 50 mA/cm2 was investigated initially for a total of 12 hours. In order to save on energy consumption, further studies used a combined current density approach. This involved applying 50 mA/cm2 for only the first hour of the test before lowering the current density to 5 mA/cm2 for the remaining 11 hours. Multiple literature IX regenerate solutions were simulated and spiked with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS).3–6 Multiple samples were taken over the course of the oxidation experiments and sent for PFAS analysis using the Environmental Protection Agency’s (EPA) modified 537 method. Additional process parameters were monitored over time including the pH, voltage, temperature, and the reduction in chemical oxygen demand (COD) and ammonia depending on the simulated regenerate solution used. Further analysis showed a significant reduction in energy with a minimal additional amount of PFAS remaining in the initial combined current density study compared to the traditional constant current density approach. 1. Woodard, S., Berry, J. & Newman, B. Ion exchange resin for PFAS removal and pilot test comparison to GAC. Remediation 27, 19–27 (2017).2. Liang, S., Pierce, R. “David”, Lin, H., Chiang, S. Y. D. & Huang, Q. “Jack”. Electrochemical oxidation of PFOA and PFOS in concentrated waste streams. Remediation 28, 127–134 (2018).3. Conte, L., Falletti, L., Zaggia, A. & Milan, M. Polyfluorinated Organic Micropollutants Removal from Water by Ion Exchange and Adsorption. in CHEMICAL ENGINEERING TRANSACTIONS 43, (2015).4. Zaggia, A., Conte, L., Falletti, L., Fant, M. & Chiorboli, A. Use of strong anion exchange resins for the removal of perfluoroalkylated substances from contaminated drinking water in batch and continuous pilot plants. Water Res. 91, 137–146 (2016).5. Chularueangaksorn, P., Tanaka, S., Fujii, S. & Kunacheva, C. Regeneration and reusability of anion exchange resin used in perfluorooctane sulfonate removal by batch experiments. J. Appl. Polym. Sci. 130, 884–890 (2013).6. Deng, S., Yu, Q., Huang, J. & Yu, G. Removal of perfluorooctane sulfonate from wastewater by anion exchange resins: Effects of resin properties and solution chemistry. Water Res. 44, 5188–5195 (2010).

(Keynote) The Versatility of TiO2 Nanotubes As Platform to Construct Photocathode or Photoanode for Clean Energy Production

The development of new technologies to convert solar energy into solar fuels through the synthesis of innovative photoactive materials is a topic of great interest nowadays. By manufacturing photo-electrodes designed with purpose to mimic the plant leaves, solar energy can be harvested and used to produce higher value-added compounds (methanol, ethanol, formic acid, methane, and others) from CO2 conversion or hydrogen from water splitting. So, the present work aims preparing, characterizing and testing semiconductor electrodes based on Ti/TiO2 nanotubes (TNT) modified with bismuth vanadate (BiVO4) or cuprous oxide (Cu2O) in the photoelectrocatalytic water splitting (water oxidation) and reduction of CO2, respectively. Considering that the photoelectrocatalytic process on the TNT surface is very small due to the lack of visible-light response and high recombination of electron-hole pair, that takes to low quantum efficiency of the process, its coupling with other semiconductors, such as BiVO4 or Cu2O can increase light absorption to the visible region and decrease the recombination of the electron-hole pair by the formation of heterojunction, therefore increasing both the processes. The TNT electrodes were prepared by electrochemical anodization of titanium sheets. BiVO4 was prepared by microwave-assisted hydrothermal method by using a commercial microwave synthesizer system [1]. Cu2O nanostructures with different morphologies were prepared as described by [2]. For water splitting, TNT electrodes were decorated with BiVO4 nanoparticles (TNT/BiVO4) by spin or spray coating method using Nafion® (Nafion® perfluorinated resin solution 5 wt. %) as an anchoring agent. On the other hand, for CO2 reduction, the Cu2O nanoparticles (cube, Nc; sphere, Ns; octahedron, No) layers on the catalysts were obtained using two sequential dip-coating procedures, after pre-coating the TNT surface with polydopamine (PDA). The water splitting was carried out using a PEC reactor homemade of Plexiglas and equipped with a quartz window. In the two compartments where placed the two electrodes acting as cathode (GDL-Pt) and photoanode (TNT/BiVO4), where the evolution of H2 and O2 evolution was monitored. The electrolyte in the anodic and cathodic compartment was 1 M NaOH and 0.5 M H2SO4, respectively. A Nafion® exchange membrane was used between the two electrodes configuration for the selective transport of protons towards the cathode for H2 production. It is noteworthy that for water oxidation no external bias was applied. Notwithstanding, CO2 reduction PEC sealed system (1 kgf cm−2), performed in low bias potential (0.2 V), using 0.1 M Na2SO4 electrolyte saturated with CO2 (pH 4.5) for 2h. The system was irradiated by either UV-Vis irradiation or solar simulator. The TNT/BiVO4 spray electrode presented a very low H2 production, maybe due to the excess of BiVO4 present on the surface of the TNT electrode. However, TNT/BiVO4 spin electrode produced 21.5 μmol of H2 after 125 min of irradiation, which is 57% higher when compared to the non-modified TNT electrode. Concerning the photoelectrocatalytic CO2 conversion, it was observed that the electrodes presented a significant performance in the conversion of CO2 to methanol, when compared with bare TNT electrode (1.5 mg L−1/1.2 mg L−1): 10 mg L−1/3.8 mg L−1 (Nc), 6.0 mg L−1/1.3 mg L−1 (No) and 5.4 mgL−1/1.7 mgL−1 (Ns) under UV-Vis radiation and solar simulator, respectively. The results demonstrated the facet-dependent performance of these nanostructures as photocatalysts and the use of PDA proved to be a good strategy to obtain p-n heterojunction semiconductors with the improvement of its response in visible light region. Therefore, these results demonstrated the potentiality of using TNT electrodes modified with nanoparticles of bismuth vanadate for water splitting, or cuprous oxide for CO2 reduction, contributing to the development of efficient technologies to produce solar fuels.

Effect of polyalcohols on the anticorrosive behaviour of alkyd coatings prepared with drying oils

Alkyd paints contain resins derived from vegetable oils. Alkyd resins have regained their importance since they are mostly composed of bio-based constituents recovered from biofuels production and agro-industrial waste. The anticorrosive performance of medium alkyd paints modified with Sacha inchi and linseed oils, and different ratios of glycerol and pentaerythritol, were compared by accelerated corrosion tests (Salt Fog and Sulphur Dioxide tests). This study focuses on comparing the effect of polyalcohol and oil type on physicochemical properties of resin solutions and cured films, and consequently, on the anticorrosive behaviour of paints prepared with the resins under study. Results showed that the mixture of pentaerythritol and Sacha inchi oil improves alkyd resin properties and enhance the anticorrosive performance of alkyd paints in accelerated weathering tests.

Surface dissolution and transesterification of thermoset dimethacrylate polymer by dimethacrylate adhesive resin and organic catalyst-alcohol solution

ObjectivesTo evaluate transesterification based dissolution of dimethacrylate and epoxy polymers, the former containing ester groups. Polymer substrates were treated with an adhesive resin (Stick™ Resin) and an organic catalyst-alcohol solution (ethylene glycol and triazabicyclodecene). The surface was chemically and nanomechanically analyzed with Fourier Transform-Infrared (FTIR) spectroscopy, surface profile peak (Rp) and nanohardness and modulus of elasticity. MethodsA total of 100 specimens each of light-cured dimethacrylate polymer and heat-cured diepoxy polymer were prepared. 20 specimens were randomly selected and used as control group (0s). The remaining specimens were randomly divided into 40 each for treatment with an Stick™ resin and ethylene glycol+triazabicyclodecene. Within each group the 40 specimens were randomly subdivided into 20 each for treatment at 5min and 24h, with 10 specimens for FTIR and nanohardness and modulus of elasticity, and the other 10 for SEM and surface Rp analyses. ResultsDimethacrylate polymer showed a reduction in the nanohardness and modulus of elasticity, Rp values and SEM also showed significant topographical changes after being treated with either Stick™ resin or ethylene glycol+triazabicyclodecene, whereas epoxy resin substrate did not. FTIR analyses affirmed changes in the intensity of ester groups. SignificanceEster group containing dimethacrylate polymer showed a reduction in NMP within 5min of exposure to the treatment agents with softening by solution ethylene glycol+triazabicyclodecene associated to the reduction of ester groups in the polymer structure by transesterification. Epoxy polymer without ester groups was not affected by surface softening with treatment agents. Adhesive resin caused surface swelling.

Effect of acetone on mechanical properties of epoxy used for surface treatment before adhesive bonding

A thin layer of un-cured resin over metal substrates applied by using an acetone-diluted resin solution (without hardener) has been found to be beneficial to strong adhesive bonding. The resin pre-coating (RPC) solution can effectively seal sub-surface micro-cavities and increase the substrate wettability. This study examines possible aftermath effects of the acetone dilution on mechanical properties of epoxy through comparison of samples made from as-received resin and resins diluted once and twice by acetone. RPC can be accepted with confidence in substrate pre-treatments for strong adhesive bonding if no detrimental effect on epoxy properties is observed. Fourier transform infrared spectrum (FTIR) was conducted, showing the spectrogram of the resin previously diluted by acetone was the same as that of as-received resin, i.e. no change in epoxy molecular structures after complete evaporation of acetone. Strength and modulus of elasticity measured by flexural and compressive tests were compared using samples made from as-received resin, and resins diluted once and twice by acetone. Variations among results from the three groups were less than 2%, or negligible, affirming the RPC method can be used for substrate pre-treatments and stronger adhesive bonding.

Spray-freezing induced multidimensional morphology tuning of assembled spherical carbon for solar-driven steam generation

Carbon materials have been extensively researched as solar absorbers in the field of solar steam generation (SSG) for their full spectrum absorption, non-biotoxicity, and excellent photothermal properties. In this work, we provide a general ice-templating method for obtaining multidimensional carbon materials controlled by regulating the surface tension during the phase separation of phenolic resin solution. Through spraying the atomized droplets into liquid nitrogen, freeze drying, and carbonization, a type of spherical carbon material assembled with carbon nanosheets with a thickness of about 3 nm can be obtained. With the enhancement of the surface tension by spray and the adjustment of the concentration of phenolic resin, a series of morphologies of carbon materials can be obtained from nanowires to nanosheets and further to spherical assemblies. In addition, an efficient SSG system was designed by combining the carbon material with polyurethane foam as matrix, notably showing good evaporation efficiency of 81.7% with a solar flux of 500 W/m2. This work provides a new idea for the morphology control of assembled carbon materials and has achieved excellent performance in the field of photothermal conversion.

Drying enhancement of sludge with resin-type drying accelerator and its mechanism

For energy utilization of high moisture content sludge, energy saving in the sludge drying process is the first priority, since energy consumption required for drying is extremely large. To develop simple and energy saving sludge drying process applicable to small facilities, sludge drying technique using drying accelerator was newly proposed and the drying experiment of sludge mixed with a small amount of drying accelerators was carried out. In this experiment, resin solution and surfactant agent was used as the drying accelerator, which had demonstrated sludge drying enhancement, and the effect of drying accelerator addition on the sludge drying behavior and drying mechanism was evaluated by measuring the weight loss, surface contact angle and deformation size of the drying sample. There were significant differences in the drying behavior depending on drying accelerator types. Surface contact angle increased with the development of water repellency immediately after drying when the resin type accelerator was used. Whereas, surfactant agent remained the sample surface hydrophilic regardless of the dryness. The addition of resin solution prevented the warpage of the sample caused by moisture distribution inside of the sample, since resin addition enhanced internal water migration. Besides the addition of a small amount of surfactant agent to the resin had a further enhancement effect on the surface drying and internal water migration of the sample by remedying the resin dispersion in the sludge.

Effect of graphene oxide on morphological and structural properties of graphene reinforced novolac-derived carbon aerogels: A modified Quasi-Percolation Model

Graphene reinforced polymer derived carbon (carbon/graphene) aerogels were synthesized by carbonization of novolac/graphene oxide aerogels. Novolac/graphene oxide aerogels were synthesized using solvent-saturated-vapor-atmosphere technique. To this aim, 20 wt% solution of novolac resin with 0, 2, and 5 wt% graphene oxide in 2-propanol were made and were cured in an autoclave. Wet aerogels were dried in air and were carbonized at 800 °C in nitrogen atmosphere. Eliminating the time-consuming methods of drying like supercritical and freeze drying is one of the advantages of this method of synthesis of organic aerogles. Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, nitrogen adsorption/desorption, and small angle X-ray scattering measurements were used to characterize the samples. It was shown that the density, the average pore size, and the pore size distribution were affected by addition of graphene oxide nanosheets. Total pore volumes of carbon/graphene aerogels were increased and the apparent density of the samples were decreased by addition of graphene oxide nanosheets. The effect of addition of graphene oxide on pore structure was mainly on mesopore and macropore region and there was fewer changes in micropore volume. Carbon/graphene aerogels with 5 wt% graphene oxide revealed the lowest density (0.167 g cm−3) with the largest BET surface area of 580.6 m2 g−1. The surface area of the carbon aerogels in this research (>500 m2 g−1) is the largest surface area achieved by ambient drying of the wet gel. It was shown that the crystallite sizes were increased by addition of graphene oxide. Graphene oxide nanosheets acted as templates for crystallization of carbon atoms which resulted in formation of bigger crystallites during carbonization. A model has been proposed based on Quasi-Percolation Model to explain the formation of bigger crystallites in presence of graphene nanosheets.

Research into the use of marble waste as mineral filler in soil pigment-based paints and as an active pigment in waterborne paints

Producing paint using waste and soil is an efficient way of contributing to sustainable development and reducing costs in the finishing and protection of buildings. Although there are numerous studies related to paints of natural land base, there remain certain technical limitations to be overcome. Moreover, no research has been found in the literature on the use of marble waste as an active or inert pigment in the production of paint, although this waste has several pertinent properties and basic constituents. Thus, the aim of this study was to evaluate whether the use of untreated marble waste as an active pigment in building paint enables a product to be developed which meets specifications and whether the performance of soil pigment-based paints can be improved by incorporating marble waste as a mineral filler. The only preparation for using the waste and the soils as pigments was to sieve them to remove coarser impurities. The samples were formulated based on mix planning using the simplex network and consisted of: marble waste pigment (MWP), soil pigment (SP) and polyvinyl acetate resin (PVA). The amount of water varied according to the ideal viscosity range for paint application. The formulas were analyzed for hiding power (HP), abrasion resistance (AR), microbiological attack and resistance to weathering. The results showed that, for paints produced with MWP as the only pigment, the performance set out in ABNT NBR 15079:2011 was achieved above a percentage of 30% resin in solution. Furthermore, the addition of MWP to SP-based paints provided a film with higher HP and, together with the increased resin content, increased the AR of the samples. Five formulas met both HP and AR performance specifications. The percentages in the mixture were as follows: 0.3 PVA and 0.7 MWP; and 0.4 PVA and 0.6 MWP, with MWP as the sole pigment; 0.25 PVA, 0.175 YSP (yellow soil pigment) and 0.575 MWP; and 0.35 PVA, 0.175 YSP and 0.475 MWP, of YSP and MWP; and 0.25 PVA, 0.175 RSP (red soil pigment) and 0.575 MWP, of RSP and MWP. The weatherability test showed that MWP addition to the paint formula contributed to increased paint durability and improved photolytic stability. Thus, the results indicate that marble waste, as an active pigment or mineral filler, is a promising alternative for producing building paint.

Two-Step 3 D-Printing Approach toward Sustainable, Repairable, Fluorescent Shape-Memory Thermosets Derived from Cellulose and Rosin.

Efficiently converting biomass into multifunctional polymerized materials is a challenge to effect high-valued utilization of biomass resources. A two-step 3 D-printing approach has been developed to fabricate a class of robust, fluorescent shape-memory thermosets from cellulose and rosin-based photosensitive 3 D-printing resin solution. The stereolithography 3 D printing was first performed to form the first crosslinked network by UV-induced chain-growth polymerization, which fixed the shape of thermoset. Subsequently, isocyanate was applied to react with hydroxy in the monomer to form the second crosslinked network by thermally induced step-growth polymerization. The formation of a dual-cure network, leading to phase separation and increased crosslinking density, could greatly improve the mechanical and thermal properties of 3 D-printed thermosets and endow them with thermally triggered shape-memory properties and excellent repairability. The 3 D-printed thermosets are found to have strong luminescence resulting from aggregation-induced emission originating from rosin. In addition, these 3 D-printed thermosets could degrade in the presence of NaOH aqueous solution and in situ achieved a range of flexible conductive hydrogels that have important potential application in the flexible electronic materials and smart photoelectric materials.