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Silicon holds great potential as anode material for next-generation advanced lithium-ion batteries (LIBs) due to its exceptional capacity. However, its low conductivity and huge volume changes during charge/discharge process result in a poor electrochemical performance of silicon anode. This study introduces a cost-effective strategy to repurpose KL Si waste from photovoltaic industry into feedstock for LIBs. A Si@C composite with core–shell structure was synthesized from kerf loss (KL) Si waste as the primary capacity contributing ingredient. The nanoscale Si particles (Si NPs) was produced through ball milling and acid pickling of KL Si waste, and then coated a carbon shell by the pyrolyzed phenolic resin. This core–shell structure enhances the electrical conductivity of silicon-based anode, facilitates ion/electron movement, and reduces volume fluctuations of silicon during lithiation/de-lithiation process. Compared to the pure Si anode, the Li+ transmission efficiency of the Si@C anode was significantly improved, leading to a better cycle and rate performance. The resulting SP-2 electrode demonstrated a consistent capacity of 602 mAh g−1 after 150 cycles under current density of 0.5 A g−1. [ABSTRACT FROM AUTHOR]

The phenols and ammonia–nitrogen compounds in semi-coking wastewater are used to react with formaldehyde to generate phenolic resin and curing agent urotropine, so as to achieve the resourceful preparation of thermosetting phenolic resin. The effects of pH value of wastewater, reaction time, reaction temperature, formaldehyde addition amount and other conditions on the quality of phenolic resin were investigated. Response surface methodology was used to optimize the preparation conditions of phenolic resin, and the effect of ammonia on the preparation of phenolic resin was explored. Moreover, solid content, carbon yield, gel time and viscosity of the prepared phenolic resin were determined. The experimental results showed that the quality of phenolic resin prepared when the pH value of wastewater was 9.5, the reaction time was 2.5 h, the reaction temperature was 140 °C, and the additive amount of formaldehyde was 1.4 mL, phenolic resin with best quality could be obtained. The solid content of phenolic resin prepared is 94.25%, the carbon yield is 40.02%, the gel time is 92 s, and the viscosity is 1.50 × 104 mPa·s. This study has solved the problems such as high chemical oxygen demand (COD), high ammonia–nitrogen, as well as difficult degradation and treatment. [ABSTRACT FROM AUTHOR]

A printed circuit board (PCB) is an essential and central component of electronic waste and comprises majorly valuable metallic values (Sn, Pb, Cu). This study utilizes a short, fast-heating, low-temperature pyrolysis process to recover value-added tin-based alloy from spent cathode ray tube (CRT) PCB. The optimized process condition (550 °C, 10 minutes) resulted in ~ 62 wt pct solid, ~ 8.5 wt pct oil, and ~ 29.5 wt pct gas products. Sn recovery of ~ 75 pct in the Pb-Sn metallic droplet form with the purity of Sn + Pb ~ 85.2 pct at 550 °C within 10 minutes is obtained. Sn-based alloy does not form at 400 °C due to incomplete decomposition of the polymeric fraction and limited surface tension, as revealed by characterization. At higher temperatures (550 °C), the molten alloy spreads over the PCB Cu tracks due to enhanced wetting force, leading to diffusion of Sn in Cu and separation of Pb. The diffusion of Sn in Cu leads to the formation of intermetallics (Cu3Sn, Cu6Sn5) at higher residence times and temperatures, inhibiting the recovery of the alloy. Further, the quenching causes spinodal decomposition, leading to a zebra stripe pattern in the alloy, and XPS confirmed the absence of Br in the alloy. The organic functional group disappears from the residual solid char with temperature, as revealed by FT-IR. The gaseous product comprises CH4, CO, CH3OH, C2H6, C2H4, and CO2 with gross heating value of ~ 310 kJ/m3. The pyrolyzed oil comprised ~ 60 pct phenol and phenolic compounds and can be re-utilized for synthesizing phenolic resins and epoxy resin. ~ 0.19 kg of Sn-based alloy (~ 85.2 pct purity) can be recovered from 1 kg of PCB as a feedstock for the tin-making industry and soldering applications. [ABSTRACT FROM AUTHOR]

In order to solve the problem of poor stability of HPAM (partially hydrolyzed polyacrylamide) gel as a plugging agent at 150 °C, this paper investigates the preparation of a polymer gel strengthened with nano-SiO2, exhibiting good thermal stability, using a low-cost, low-hydrolysis anionic polymer. The experimental results indicated that when the gel was prepared with 1 wt% HPAM, 1 wt% water-soluble phenolic resin (WSPR) as a crosslinker, and 1 wt% nano-SiO2 as a stabilizer, the dehydration rate of the gel was less than 5 wt% after 180 days of aging at 150 °C. In order to identify the stability mechanism of nano-SiO2-strengthened polymer gel, we conducted rheological tests, Cryo-SEM analysis, Fourier transform infrared (FTIR) spectroscopy, and solid-state nuclear magnetic resonance (NMR) analysis on the polymer gel before and after adding nanoparticles. The methods described in the study demonstrate the excellent long-term thermal stability of the polymer gel strengthened with nano-SiO2 from both chemical bonding and microscopic perspectives. The results of rheological experiments indicated that the addition of nanoparticles improved the yield stress and long-term thermal stability of the gel. The scanning electron microscope (SEM) microstructure analysis confirmed that the addition of nanoparticles resulted in high-density cavities between the microscopic network structures of the gel. This facilitated the trapping of a significant amount of free water and the formation of a stable spatial mechanical support structure, ultimately enhancing the macro-mechanical strength of the gel. Additionally, FTIR and NMR experiments demonstrated that the nanoparticles effectively inhibited the hydrolysis of amide groups to carboxylate, thereby significantly preventing the high-temperature degradation of the gel and maintaining its strength after prolonged aging. [ABSTRACT FROM AUTHOR]

Phenolic resins are extensively utilized in various industries, but their production using non-renewable and petroleum-based phenol and formaldehyde raise concerns over cost and adverse effects on human health and the environment. Hence, the development of alternative phenol sources is imperative to achieve sustainable production and promote environmental sustainability in the field of polymer chemistry. This study aims to investigate the feasibility of synthesizing lignin-based phenolic resin, using fractionated acetone-treated lignin extracted from sugar waste, as a substitute for toxic and non-renewable phenols. Specifically, the acetone treatment is used for fractionating lignin to select the optimal components for phenolic resin synthesis. Experimental results indicate that the lignin exhibits improved solubility in a 60% acetone solution, leading to a simplified configuration and enhanced bonding mode. The resulting phenolic resin synthesized using lignin as a phenol source demonstrates superior bonding strength (1.57 MPa) compared to industrial phenolic resins (1.14 MPa). Furthermore, the resin exhibits a negligible amount of released free phenols (0.05%), which significantly mitigates environmental concerns. To conclude, this study presents a novel approach to develop a lignin-based phenolic resin using sugar byproduct as a feasible substitute for phenols, addressing the limitations associated with their production. These findings offer promising prospects for sustainable production practices in polymer chemistry. [ABSTRACT FROM AUTHOR]

In this paper, using NaCl as the template and in-situ polymerized phenolic resin as the carbon source, we prepared micron-sized large hollow cubic carbon. With the increase of stirring speed, the particle size, cavity size and shell thickness of hollow cubic carbon (HCCs) increased gradually. The sample with stirring speed of 1500 r/min (HCCs-5) obtained strong loss capacity (RLmin = − 43.99 dB), wide bandwidth (EAB = 5.22 GHz) and thin thickness (2.0 mm) under very low load (1.5 wt%), taking into account the requirements of "strong, wide, light and thin" of modern wave absorbing materials. The hollow cube structure of HCCs can make the electromagnetic wave be reflected several times in its interior, and the electromagnetic wave is lost. The formation of a three-dimensional conductive network between adjacent HCCs will lead to an increase in conductivity and a certain conduction loss. More importantly, the mesoporous structure provides interfacial polarization, and the synergy of these loss mechanisms together ensures excellent wave absorption performance. [ABSTRACT FROM AUTHOR]

The article proposes a method for producing polyaniline-modified nanocomposite cryogel based on oxidized carbon nanotubes and reduced graphene oxide. Phenol–formaldehyde resin has been used as a crosslinking agent. Cryogel has been obtained by freeze drying in vacuum. Then, the material has been subjected to a post-processing, i.e., the carbonization in a tubular furnace. The obtained nanocomposite has been subjected to the comprehensive diagnostics by the methods of scanning and transmission electron microscopy, IR spectroscopy, X-ray diffraction analysis, and Raman spectroscopy. The parameters of the pore space have been estimated by nitrogen adsorption. It has been found that the carbonized nanocomposite cryogel is a mesoporous material with a specific surface area of 299 m2/g. IR and Raman spectra and X-ray diffraction patterns of the starting materials have been compared with the spectra of the carbonized cryogel. According to the results obtained, the nanocomposite exhibits peaks of all starting materials. The sorption capacity of the material has been evaluated by the example of the sorption of ions of a heavy metal, lead, from model aqueous solutions. Kinetic studies of adsorption in a limited volume have been carried out to determine the mechanism and time of the adsorption. It has been revealed that 99% of the contaminant is sorbed during the first 15 min, while an adsorption capacity of 295 mg/g is reached. The Elovich model, pseudo-first- and pseudo-second-order models, and an intradiffusion model have been employed to confirm the proposed adsorption mechanism. [ABSTRACT FROM AUTHOR]

Polybenzoxazines (PBz) are a new type of resin belonging to the category of phenolic resins. As polybenzoxazines are addition-curable polymers, this obviates many of the shortcomings associated with conventional phenolic resins while endowing them with excellent thermal, physical, and thermo-physical properties and surpass the features of many conventional and state-of-the-art polymers. They even possess excellent design flexibility. In this study, a benzoxazine monomer was successfully synthesized from eugenol (Eu), ethylenediamine, and paraformaldehyde utilizing a solventless approach. The synthesized benzoxazine resin was characterized for its structural elucidation via FTIR, 1H, and 13C NMR spectroscopy and was used for crosslinking a petroleum-based epoxy and a gallic acid-based epoxy. The effects of the presence of benzoxazine on the thermal and flame retardant properties of the films were evaluated using TGA and DSC analysis and the LOI and UL 94 tests, respectively. It was found that the benzoxazine in the epoxy systems led to an increase in thermal stability and flame retardancy. The gallic acid-based epoxy system showed better thermal and flame retardant properties compared to the petroleum-based epoxy system, thus showing potential to replace the petroleum-based epoxy for high-performance applications. [ABSTRACT FROM AUTHOR]

The synthesis of Bisphenol A Glutaraldehyde Phenolic Resin (BPA-GA PF) was carried out under alkaline conditions using Bisphenol, A (BPA) and Glutaraldehyde (GA) as raw materials, with n-butanol serving as the solvent. Based on the aforementioned information, the researchers prepared modified BPA-GA PF resins by incorporating titanium (Ti), silicon (Si), and boron (B) through a polymer derivative method. This process led to the formation of Ti/Si/B-modified PF resins. By manipulating the proportion of elements in the BPA-GA PF, the modified phenolic resin demonstrated improved capacity for design and processing. The characterization of the modified BPA-GA PF involved the analysis of its transformation process and thermal behavior through the utilization of Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric Analysis (TGA). The presence of B, Ti, and Si elements in the system resulted in the formation of Si–O-B and B-O bonds, as determined. The Ti/Si/B -modified PF exhibited a significant increase in yield. Analysis employing X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) revealed that, following high-temperature annealing, the materials underwent a transformation into Ti/Si/B-modified PF with a highly cross-linked network structure. Oxidation experiments conducted under static conditions demonstrated that the Ti/Si/B-modified BPA-GA PF exhibited significantly greater high-temperature resistance compared to the BPA-GA PF. Among the various options, the Ti/Si/B-modified PF material with a Ti/Si ratio of 1:2 exhibited the most superior resistance to high-temperatures. [ABSTRACT FROM AUTHOR]

It is of interest to develop wide-temperature domain damped hydrophobic materials. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. In this paper, we designed incorporating bio-based phenolic resin into the IIR matrix and introducing dibenzyl fork acetone (DBA) into the main chain structure with sodium hydroxide activation to construct three-dimensional network. The added bio-based phenolic resin has reticulated structure blended with butyl rubber, combined with sodium hydride activation-modified IIR. The results show that sodium hydride activated modification of DBA is introduced into the main chain structure of IIR by infrared and 1H NMR analysis. The material hydrophobic is realized by the introduction of DBA with static water contact angle of 103.5°. The addition of 10phr lignin-based phenolic resin (LPF) is compatible with IIR, and the torque can reach 7.0 N-m. The tensile elongation of the modified butyl rubber composite can reach 2400% with tensile strength up to 11.43 MPa, while the damping factor can reach 0.37 even at 70 °C. The thermal stability of the composites is enhanced with mass retention rate of 28%. The bio-based PF/NaH activation-modified butyl rubber damping material has potential applications in damping hydrophobicity with wide temperature range. [ABSTRACT FROM AUTHOR]

The main purpose of a liquid binder in the composition of mineral wool products is to bond individual fibers to each other to create a strong and elastic structure. The combined use of an organic (phenol-formaldehyde resin) and an inorganic binder based on cold dissolution liquid glass is accompanied during their mechanical mixing by the formation of complex carbon-silicon compounds, which stabilize the formation of chelate compounds with an orienting effect of silicon ion during heat treatment, converting the polymer structure to a more ordered and dense structure with additional bridging hydrogen bonds. This process is accompanied by the parallel development of a polycondensation reaction of the organic binder and methylol groups and curing of the liquid glass. The presence of intramolecular bonds between the organic and inorganic parts of the binder increases the bond strength of the mineral fibers when forming the structure of fibrous thermal insulation materials by 20 – 30% with a slight increase in their water absorption. Limited use of cold dissolution liquid glass additives (not more than 0.4%) allows a reduction in the total consumption of organic binder by 20 – 25% with the possibility of reducing the required amount of mineral part by up to 10 – 15% while maintaining the required strength and operational properties of finished heat-insulating products. [ABSTRACT FROM AUTHOR]

Hard carbon has been widely used in anode of lithium/sodium ion battery, electrode of supercapacitor, and carbon molecular sieve for CO2 capture and hydrogen storage. In this study the lignin derived hard carbon products are investigated, and the conclusions are abstracted as follows. (1) The lignin derived hard carbon products consist of microcrystal units of sp2 graphene fragments, jointed by sp3 carbon atoms and forming sp2–sp3 hybrid hard carbon family. (2) From the lignin precursors to the sp2–sp3 hybrid hard carbon products, most carbon atoms retain their original electron configurations (sp2 or sp3) and keep their composition in lignin. (3) The architectures of lignin-derived hard carbon materials are closely dependent on the forms of their lignin precursors, and could be preformed by different pretreatment techniques. (4) The carbonization of lignin precursors follows the mechanism "carbonization in situ and recombination nearby". (5) Due to the high carbon ratio and abundant active functional groups in lignin, new activation techniques could be developed for control of pore size and pore volume. In general lignin is an excellent raw material for sp2–sp3 hybrid hard carbon products, a green and sustainable alternative resource for phenolic resin, and industrial production for lignin derived hard carbon products would be feasible. [ABSTRACT FROM AUTHOR]

Phenol-formaldehyde resins combined with polymers have a wide range of industrial applications as plugging agents for profile control and enhanced oil recovery. Due to the structural resemblance between lignin and phenol, there are possibilities for environmentally friendly phenol-formaldehyde resin manufacturing. Sulfonated lignin–based phenol-formaldehyde resin was synthesized by partially replacing phenol with lignin, which improved the utilization rate of lignin and achieved the purpose of environmental preservation and resource conservation. Partially hydrolyzed polyacrylamide is the most widely used polymer in chemical methods for enhanced oil recovery. However, the stability of reservoirs with high salt and high temperatures is weak under these conditions. To solve the problem of low oil recovery in high-salt reservoir environments, polymer flooding is adopted, which utilizes high-molecular-weight polymers to raise the viscosity of injected fluids, thereby improving sweep efficiency and altering mobility ratio between oil and injected fluid. We focus on the stability study of different molecular weights partially hydrolyzed polyacrylamide combined with sulfonated lignin – based phenol-formaldehyde resins in metal ions and surfactants. The zeta potential and hydrodynamic diameter of the partially hydrolyzed polyacrylamide – sulfonated lignin – based phenol-formaldehyde resin system in Ca2+ were measured by dynamic light scattering and static light scattering, and the dispersion stability was analyzed. The interfacial energy – modified DLVO theory was introduced to evaluate the stability of its colloidal solution, which made it possible to predict the aggregation behavior of sulfonated lignin – based phenol-formaldehyde resin and the co-migration process of metal cations in real time. [ABSTRACT FROM AUTHOR]

In this work, the effect of irradiation with 5-MeV electrons on the adhesive and strength properties of the films of diazoquinone–novolac photoresists FP9120, SPR-700, and S1813 G2 SP15 deposited on single-crystalline silicon wafers by spin-coating has been studied using the indentation method. It has been established that irradiation leads to an increase in the true microhardness of the photoresist films, most pronounced in SPR-700 films, caused by the crosslinking of phenol–formaldehyde resin molecules. It has been shown that the values of the specific peeling energy G of photoresist films on silicon increase upon irradiation as a result of the recombination of radicals at the photoresist/silicon interface with the formation of new covalent bonds Si–C and Si–O–C. The observed experimental results are explained taking into account the radiation-chemical and relaxation processes occurring in the bulk of the polymer film and at the interface. [ABSTRACT FROM AUTHOR]

Photoresist (PR) NFR 016D4 films deposited on the surface of silicon (Si) wafers by centrifugation were studied by attenuated total internal reflection Fourier-IR spectroscopy. Background absorption of the PR/Si structures was observed to increase at wave numbers <1600 cm−1 because of the effect of electromagnetic radiation on the Si substrate and scattering/reflection at the PR/Si interface. Asymmetry in the force field of the aromatic ring in the NFR 016D4 film was detected. Spectral features of thick PR NFR 016D4 films were due to the presence of residual solvent. Formaldehyde formed by fragmentation of hydroxymethyl residues in the phenol-formaldehyde resin was detected in irradiated films. Radiation-induced processes in PR NFR 016D4 films at doses up to 2∙1015 cm−2 involved mainly residual solvent molecules or by-products of PR film synthesis. [ABSTRACT FROM AUTHOR]

In this research, nanocomposite samples made of rezole phenol formaldehyde resin (Phenolic) (PF)/short carbon and glass hybrid fibers (CGF) with clay nanoparticles reinforced by sintering and molding method with high pressure and temperature have been performed. The results showed that short carbon and glass hybrid fibers in phenolic resin, two important characters including failure strain and final strength, compared to samples without hybrid fiber carbon and glass improved and an optimal sample is extracted. From the XRD and EDX spectra, it was found that with the increase in the weight percentage of clay nanoparticles, the peak intensity increased, that is, the dispersion of nanoparticles in the matrix has increased. Also, SEM photograph showed that with the presence of clay nanoparticles in the composite, the amount of adhesion and penetration between the matrix and the fibers increased that this has increased the strength composite. The results obtained for nanocomposite samples with hybrid fibers reinforced with 1 wt% of clay nanoparticles, modulus of elasticity for tensile test about 12%, for bending test about 27% and for buckling test increased about 16% compared to composite samples without nanoparticles. The results of impact test also showed that the nanocomposite sample reinforced with 1 wt% of clay nanoparticles had the highest energy absorbed compared to other samples. [ABSTRACT FROM AUTHOR]

Research on graphite as anode material for lithium-ion batteries (LIBs) has been carried out for a long time. Natural microcrystalline graphite (MG) with low cost and eco-friendly properties is a promising anode for LIBs. However, the tiny and irregular MG would cause serious side reactions with electrolytes and reduce the efficiency of energy storage. Here, the alkali fusion acid leaching method is employed for the purification of MG. After removing impurities, the purified MG is bound and wrapped by phenolic resin pyrolytic carbon to form secondary particles (PCG). Benefiting from the formation of secondary particles with a carbon shell, PCG exhibits a high specific capacity of 354.3 mAh/g and outstanding rate performance (82.7% capacity retention at 2 C). Meanwhile, outstanding cycling stability is demonstrated, with 92.7% capacity retention after 500 loops at 2 C. This research cleverly employs phenolic resin pyrolytic carbon to bind and wrap fragmented MG into secondary particles by a one-step method for high-performance LIBs anode. Such a "one stone two birds" strategy is cost-effective, environmentally friendly, and simple to operate, which is highly valuable for practical applications and provides a reference for the optimization of other graphite materials. [ABSTRACT FROM AUTHOR]

Soft magnetic composites (SMCs) were prepared by uniformly mixing reduced Fe powder with nano-AlN particles and phenolic resin by powder metallurgy. The effects of AlN content on the microstructure, density and magnetic properties of iron-based soft magnetic composites were investigated. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analysis showed that the sample prepared with AlN/phenolic resin insulation has a thin and uniform coating layer. Compared with the single inorganic AlN-coated sample, the AlN/phenolic resin composite coating method resulted in increased electrical resistivity and compact density, reducing the eddy current loss and effectively reducing the magnetic loss of the soft magnetic composites. The 4 wt.% AlN/phenolic resin soft magnetic composite had the lowest magnetic loss (147.67 W/kg@100 kHz,0.05 T), which was 90.4% lower than that of a single AlN-coated sample, and the permeability of the sample was stabilized at 90 in a wide range of frequencies. [ABSTRACT FROM AUTHOR]

The review addresses methods for modification of phenolic resins via introducing reactive compounds into synthesis and the reactions of hydroxyl phenolic and methylol groups which allow the preparation of adhesives with improved performance characteristics. [ABSTRACT FROM AUTHOR]

Epoxy adhesives are one of the polymers used as high-performance matrix in adhesives. However, the high brittleness and low toughness of epoxy adhesives are critical challenges during their service in structural applications due to their high-crosslinking degree. The lack of appropriate high-temperature thermal stability is another drawback of these valuable materials. This study addressed the effect of hybrid reinforcement comprising zirconium oxide nanoparticles (NPs), phenolic resin (resol type), and poly (butyl acrylate-block-styrene) copolymer (BCP) on mechanical, adhesion, thermal, and morphological properties of the epoxy adhesive. Mechanical properties, thermal stability, and microstructure of the epoxy adhesive was assessed using tensile test, TGA, and FESEM tests, respectively. The adhesion features of the formulated adhesive were evaluated in lap joint bonding of an aluminum to aluminum. A new approach was developed to design advanced adhesives with high mechanical, adhesion, and thermal properties by adding hybrid additives. Based on the tensile test results, adding 5 phr of zirconium oxide nanoparticles to the epoxy adhesive increased the tensile strength, modulus, and the toughness of the dumbbell-shaped samples by 69, 33 and 175% compared to the neat epoxy adhesive, respectively. Furthermore, the sample containing 10 phr phenolic resin, 5 phr zirconia NPs, and 2.5 phr block copolymer exhibited the highest improvement (420%) in the shear strength in the single lap joint increment compared to pure epoxy, reflecting the synergistic impact of these compounds at the mentioned percentage. The TGA results indicated the highest initial degradation temperature in the sample containing 5 phr zirconia NPs which was 54.4 °C higher than that of the pure epoxy. The images of the fracture surface of the optimal samples in the tensile test showed the cavitation, shear band formation, crack deviation, and crack tip blunting as major mechanisms in the toughness enhancement of the samples. [ABSTRACT FROM AUTHOR]

Enhanced oil recovery research focuses on the phenol–formaldehyde resin (PFR) solution (EOR). We studied PFR's morphology and aggregation kinetics at various pH levels. A hydrated layer formed on the surface of PFR as a result of hydrogen bonding between the hydroxyl and phenolic hydroxyl groups and water molecules. We quantitatively quantified the impact of pH on the morphology and aggregation kinetics of PFR by incorporating the hydrated force into the DLVO (Derjaguin Landau Verwey Overbeek) theory. We were able to predict the situation of aggregates plugging into the reservoir by altering the size of PFR aggregates in a capillary. [ABSTRACT FROM AUTHOR]

Lignin was modified by degradation to have more high active sites. Depolymerized lignin-based phenolic resin was synthesized to protect the environment and reduce the cost. Under the optimal conditions of sodium hydroxide catalysis, the effect of different concentrations of Na2S2O3 on the depolymerization of lignin was studied by the microwave depolymerization and the hydrothermal reaction. The depolymerized lignin had the highest phenolic hydroxyl content of 22.41% and 22.35% by two methods, respectively. LC-HRMS showed that the molecular weights of the depolymerized lignin decreased significantly. SEM showed that the surface of the depolymerized lignin-based phenolic resin was smooth and tightly connected. The adhesive had the highest bonding strength of 2.94 MPa. When lignin replaced 100 wt% phenol, the bonding strength of this adhesive could reach 1.57 MPa. This showed that when the lignin with complex structures was degraded, industrial adhesives with high bonding strength could be successfully obtained. [ABSTRACT FROM AUTHOR]

Phenolic adhesives used in modern engineering industries, including aircraft and rocket manufacturing, are reviewed. Ways to modify adhesives to achieve high performance characteristics are discussed. [ABSTRACT FROM AUTHOR]

In this article, phenolic resin samples of Resole reinforced with carbon fibers and graphene nanoparticles were prepared. Different amounts of graphene (0.5%, 1%, 2%, and 3%) were dispersed in a 50% solution with weight of phenolic resin and ethanol with ultrasonic waves for 10 min with 60% power of the device. After that, hybrid composites containing 50% with weight of carbon fibers were prepared with manual layering method and the samples were baked at 160 °C, 120 bar pressure with hot pressing. The morphology and thermal and mechanical properties of the prepared nanocomposites were examined with XRD, FTIR, SEM, TEM, DSC, TGA, and three-point bending tests and the results were compared with adding 1% with weight of graphene to the resulting composites; the modulus and flexural power of the samples rose with 19.5% (38.2GPa) and 8.7% (471MPa), respectively. Also, the shear strength of the sample containing 1% graphene with weight increased with 23% compared to the pure sample. The thermal resistance of phenolic resin/graphene composites showed a significant increase compared to pure resin. For example, in the sample containing 1% with weight of graphene, the observed increase in T5%, T10%, and Td, max indices were 12, 30, and 5°C, respectively. The DSC test results indicated that the addition of graphene nanoparticles decreases the enthalpy of the baking reaction and also shifts the exothermic peak to higher temperatures. This can indicate the steric hindrance effect of the graphene sheets during the baking reaction, which is caused with the huge surface area of the graphene sheets. [ABSTRACT FROM AUTHOR]

Membrane-based separation technology has attracted enormous attention for oil/water emulsion treatment. Here, composite microfiltration carbon membranes (MCMs) were prepared from the precursor of phenolic resin doping with TiO2 and Fe2O3 via the processes of stereotype and pyrolysis. The functional groups, thermal stability, porous structure, microstructure, morphology, and hydrophilicity of the membrane samples were analyzed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, bubble pressure method, X-ray diffraction, scanning electron microscope, and water contact angle, respectively. The effect of dopant amount on the separation performance of MCMs was investigated. The results show that a mixed matrix system is constructed by TiO2 and Fe2O3 in MCMs, which is beneficial for further optimizing the pore size, porosity, and hydrophilicity of MCMs for oily wastewater treatment by varying the dopant amount. The maximum oil rejections are achieved at 98.9% and 99.6% for MCMs with a dopant content of TiO2 and Fe2O3 at 25%, respectively. In brief, this study offers an attractive strategy for improving the separation performance of MCMs for oily wastewater. [ABSTRACT FROM AUTHOR]

Wood modification by impregnation and curing inside of the cell wall using phenol–formaldehyde resins (PF resins) is a well-known and commercialized method to improve, amongst others, the dimensional stability and the durability of wood. However, phenol is mainly obtained from non-renewable resources, and the substitution of phenol by renewable resources has been a topic of research interest for years. Due to the high availability of technical lignins, lignin-derived cleavage products are promising candidates. In this study, organic cleavage products obtained from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin were used to substitute up to 45% of phenol in PF resins. The curing behavior and the free formaldehyde content of the resins was studied. Pine sapwood was treated with these resins by a vacuum pressure treatment, and the weight percent gain, leaching, and dimensional stability of the species were examined. Selected samples were analyzed with bright-field microscopy. The results indicate that up to 30% substitution of phenol by lignin-based organic products does not lead to significantly inferior quality of wood modification. Additionally, the amount of formaldehyde added to the resin can be reduced. The method described in this study could be a way to improve the environmental footprint of wood modification by PF resins. [ABSTRACT FROM AUTHOR]

The commonly used phenolic resin vulcanizing agents for rubber processing technology have some limitations. In this study, a new aldehyde teroctyl phenolic resin vulcanizing agent was synthesized from SP-1055 through a series of chemical reactions and tested for its efficiency in vulcanizing isoprene rubber (IR) at low dosages. The structure of the new phenolic resin was confirmed using infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The results showed that the new phenolic resin exhibited excellent vulcanization properties and environmental protection characteristics, and the IR blended with the new phenolic resin vulcanizing agent showed higher tensile strength, elongation at break, and better recovery from prolonged extension than those of IR with traditional phenolic resin vulcanizing agents. The improvement is attributed to the replacement of the chain end hydroxyl with an aldehyde group in the new phenolic resin vulcanizing agent. The new phenolic resin vulcanizing agent has significant potential for future research and development and could be a promising alternative for medical rubber products. [ABSTRACT FROM AUTHOR]

We design and prepare porous N-doped carbon sub-microspheres (Por-N–C-SS) using the phenolic resin sub-microspheres as precursor and potassium hydroxide as pore forming agent by polymerization-carbonization strategy. Pt and Cu ions are impregnated on surface of Por-N–C-SS, and then PtCu/Por-N–C-SS are obtained by a facile reduction process. The as-fabricated Por-N–C-SS exhibits the spherical structure with the diameter size of 200–500 nm. And Por-N–C-SS also possesses high specific surface area of 2222 m2 g−1 and large pore volume of 1.02 cm3 g−1. Benefiting from alloy effect of highly dispersed PtCu and N-doped porous carbon architecture, PtCu/Por-N–C-SS shows excellent electrocatalytic performance toward methanol oxidation reaction with high peak current density (4661 mA cm−2 mg−1 Pt) and large Jf/Jb value (1.18), exceeding commercial Pt/C catalyst in acid media. Furthermore, PtCu/Por-N–C-SS also reveals an outstanding catalytic stability, promoting its practical application in fuel cells. [ABSTRACT FROM AUTHOR]

Lightweight and chemically stable carbon are widely applied as attractive microwave absorption materials (MAMs). However, the effective response bandwidth of pure carbonaceous MAMs is limited due to the imbalance between conductivity and polarization loss. Herein, carbon with a large number of amorphous/nanocrystalline uneven phase interfaces prepared from commercial phenol–formaldehyde resin (PF) through simple anoxic carbonization exhibited excellent microwave absorption performance by balancing conductivity and polarization loss. Benefiting from the modification of the carbon nanocrystalline, a suitable electrical conductivity is obtained with a large number of amorphous/nanocrystalline uneven phase interfaces, allowing more incident microwaves to be lost. Thus, PF-650 exhibits a strong reflection loss of − 59.62 dB and a broadband effective microwave absorption of 6.32 GHz at 2.35 mm. In contrast to typical carbonaceous MAMs with multiple chemical compositions and complicated microstructures, this work provides a promising approach to the preparation of highly efficient and yielding carbonaceous materials for practical applications. [ABSTRACT FROM AUTHOR]

The rhizomes of ginger have been in use in many forms of traditional and alternative medicines. Besides being employed as condiment and flavoring agent, it is used in the treatment of nausea, osteoarthritis, muscle pain, menstrual pain, chronic indigestion, Alzheimer's disease, and cancer. Ginger rhizome contains volatile oils, phenolic compounds and resins, and characterization studies showed that [6]-gingerol, [6]-shogaol, and [6]-paradol are reported to be the pharmacologically active components. Gingerol is a major chemical constituent found as volatile oil in the rhizomes of ginger. It has several medicinal benefits and used for the treatment of rheumatoid arthritis, nausea, cancer, and diabetes. Many studies have been carried out in various parts of the world to isolate and standardize gingerol for their use as a complementary medicine. The present review summarizes wide range of research studies on gingerol and its pharmacological roles in various metabolic diseases. [ABSTRACT FROM AUTHOR]

The stability of phenol–formaldehyde resin (nHAP) in the oil displacement process influences its flooding and profile control capabilities. There aren't many studies that compare how various surfactants affect PFR stability. The surfactants CTAB, Tween 60, and SDS were selected as representative ones. To look at the changes in stability, spectral turbidity and dynamic light scattering experiments were employed. It was found that the cationic surfactant CTAB can connect with the surface of PFR, just as metal cations, lowering electrostatic repulsion and facilitating the aggregation of PFR composite molecules. Anionic and nonionic surfactants both have some degree of system stability stabilizing properties. When Tween 60 and SDS adsorbed on the surface of the PFR molecule formed a hydrogen bond network with the hydroxymethyl or phenolic hydroxyl group, for example by hydrogen bond interaction, the PFR molecule's dispersion stability was increased. The Tween 60 and PFR composite systems have bigger particle sizes in addition to being more stable. Additionally, the energy barrier of the Tween 60/PFR composite system is determined using the modified DLVO theory for Lewis acid–base hydration, and it is discovered to be consistent with the experimental findings. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. The findings demonstrate that the stability of the composite system can be impacted by changes in the hydrophilicity and hydrophobicity of the composite system. Understanding the co-migration of PFR and surface activity during oil displacement depends heavily on the data. [ABSTRACT FROM AUTHOR]

The use of highly mineralized reinjection water has low gel strength and poor stability, and the above problems are more prominent under high-temperature reservoir conditions. Based on the temperature resistance and salt tolerance polymer TSRP and phenolic resin crosslinking agent, a TSRP temperature resistant weak gel system suitable for high mineralized reinjection water was developed, and the temperature resistance mechanism of the TSRP weak gel system was tested by its temperature resistance and injection ability. The migration, retention, and plugging of the TSRP weak gel system in heterogeneous reservoirs were studied through micropore throat migration and plugging characteristics and dual-pipe parallel oil displacement experiments. The results showed that: under the condition of polymer concentration 2000 mg/L, polymer: crosslinking agent: glue promoter 1:1.5:1, the TSRP weak gel system prepared by using mineralized 12132.9 mg/L reinjection water can remain stable after 95°C aging at high temperature of TSRP. Through microscopic simulation, a glass etching model TSRP weak gel system showed good migration ability and plugging performance. In comparison with the two pipes parallel oil displacement experiment, the KY gel system injected the same amount of PV at 95°C and 20000 mg/L in the Y1L block, the average recovery of the TSRP gel system increased by 22.3% after injection of polymer gel, and the KY gel system was only 18.2%; When the same amount of PV was injected in Z1L block, 95°C and 22000 mg/L, the average recovery of TSRP gel system increased by 24.35% after injection of polymer gel, and the KY gel system was only 17.15%, that is, under higher salinity, the TSRP gel system showed better performance. [ABSTRACT FROM AUTHOR]

Phenols are commonly encountered in the aqueous effluents of different industrial processes, such as oil refining, and phenolic resin manufacturing and processing. Because phenols are toxic, they should be promptly removed from aquatic environments. Herein, we describe the preparation of photocrosslinked β-cyclodextrin (β-CyD) polymer beads and their use for the removal of phenol (PhOH) from the raw industrial wastewater from phenolic resin processing. Polysubstituted photocrosslinkable β-CyD (PSβCyD/UV) sorbent beads were obtained via the reaction of globed macromonomers with sodium alginate and calcium chloride followed by photocrosslinking the β-cyclodextrin (β-CyD) macromonomers with isophorone diisocyanate and 2-hydroxyethyl acrylate (molar ratio of 1:3.5:3.5). The physical properties of the fabricated PSβCyD/UV beads were as follows: average diameter, 2.7 mm; average compressive strength, 6.5 M Pa; porosity, 41.4%; and specific surface area, 2.89 m2/g. The removal of PhOH from raw industrial wastewater using β-CyD polymer beads was performed in a shaker at 25 °C. After six accumulated adsorption cycles, the PhOH concentration decreased from of 89,000 to 1500 mg/L; furthermore, the expansion factor of PSβCyD/UV was 1.33. Adsorbent PSβCyD/UV polymer beads with a regular spherical shape and high mechanical stability were prepared using a photocrosslinking method. The results of the sorption experiments indicated that the PhOH adsorption capacity of the polymer beads from raw industrial wastewater was high (2.43 mmol/g-resin). We concluded that the prepared polymer beads formed rich polymer network structures, which affected the physical adsorption of PhOH and the chemical interactions with PhOH via hydrogen bonding. [ABSTRACT FROM AUTHOR]

Olive oil mill wastewater (OMW), a by-product of the olive oil industry, each year is generated millions of tons all over Mediterranean countries. Uncontrolled disposal of the OMW leads to massive environmental problems including soil and water pollution. In this experimental study, the OMW was used to partly replace clean water for getting prepared formaldehyde solution. Then, phenol and formaldehyde solutions were synthesized under alkali conditions to obtain more green phenol–formaldehyde (PF) resin. The effect of the OMW substitution level on the chemical and thermal properties of PF resin was examined by the Fourier transform infrared (FT-IR) spectral and thermogravimetric (TGA) analysis, respectively. Moreover, the bonding strength of each PF resin was evaluated under dry and wet conditions. It was found that FT-IR measurements showed that the PF resin containing various amounts of the OMW had a chemical structure very similar to the PF resin. The thermogravimetric analysis demonstrated that the low‐molecular‐weight organics in the OMW had negatively affected the thermal stability of the modified PF resins. In addition, the wood samples bonded with the PF resin containing up to 30 wt% OMW met the minimum requirements of interior and exterior bonding performance according to standard EN 12765. The OMW could be replaced by clean water up to 30 wt% for the production of green phenolic resin. [ABSTRACT FROM AUTHOR]

Phenolic resins are the most commonly used binders in brake pads for automotive disc brake systems owing to their affordability and thermal properties. However, they also show some limitations related to their crosslinking mechanism. Benzoxazine resins present themselves as possible alternatives for this application by providing enhanced thermal properties as well as other industrially attractive characteristics such as lower moisture absorption and unlimited shelf life. This study investigates the thermal properties of two different benzoxazine resins, with the aim of assessing their capabilities as binder for brake pad and of understanding how to process them in order to actually employ them as such. DSC, TGA, hardness and tribological analyses were carried out on neat resin samples and on friction materials containing them as binder. The presence of several concurring reactions was detected during the crosslinking reaction of benzoxazine resins. The benzoxazine resins showed lower mass loss respect to a phenolic resin in the temperature range of interest for commercial brake pads application. Friction material containing benzoxazine resin binder showed promising tribological results. [ABSTRACT FROM AUTHOR]

Using bisphenol A (BPA) and isophthalaldehyde (IPD) as comonomers, based on open system and solution polycondensation method, phenolic resin was prepared by microwave. The reversible thermochromic composite solution polymerized butadiene styrene rubber film was prepared by resin as chromogenic agent. The resin was tested by gel permeation chromatography, 1H and 13C NMR spectrometers, thermogravimetric analyzer, and thermal analyzer, etc. The composite film was tested by thermogravimetric analyzer, thermal analyzer, spectrophotometer, and polarizing microscope, etc. The factors affecting the thermochromic properties, thermal stability, thermal recyclability stability and microscopic morphology of the composite film were studied. The results indicate that BPA-IPD is the 2,6-monosubstituted bisphenol A isophthalaldehyde phenolic resin with M–n of 1.150 × 103 g mol–1 and PDI of 1.004. Therefore, the number of monomers in molecular chain containing BPA and IPD are 3 and 3, respectively. When the mass ratio of crystal violet lactone, resin, mixed alcohols (cetyl alcohol and octadecanol) and solution polymerized butadiene styrene rubber is 1 : 1.5 : 30 : 50, i.e., 0.0075 : 0.011 : 0.23(0.14 : 0.09) : 0.38(g), the composite film is obtained by salivation method. The total color difference (ΔE) of composite film is about 90, and its absorption/scattering color depth difference [Δ(K/S)] values are averagely 20 and 40 at visible light zone of 480– 600 and 600–660 nm at the low temperature region (10–33°С) of phase change during constant speed cooling, respectively. The composite film has good thermal stability and recyclability stability. [ABSTRACT FROM AUTHOR]

To improve the fire extinguishing efficiency and reduce the re-combustion risk, a novel approach to fire extinguishing using sodium pyrotechnic aerosol (SPA) was adopted for controlling underground mine fires. Physical simulation experiments of 1 m3 in size show that the extinguishing effect of aerosol consisting of NaNO3 and dicyandiamide is better than that of 0.2 MPa nitrogen, in which the cooling rate peaks at 32.6 °C min−1. Experiments result prove that the N2 and CO2 yield of aerosol reach about 10 mol s−1 m−3 and 5 mol s−1 m−3, respectively. As an additive, phenol–formaldehyde resin embodies advantages compared with agents such as K2C2O4, CH4Mg2O6, and potassium hydrogen phthalate. According to TG/DTG tests, characteristic temperature points of coal with SPA can be increased significantly, and the apparent activation energy of coal also increases to 18.8–80.5%. Theoretically, Na-salt generated by aerosol reaction consumes the O-contained groups in coal and creates an alkaline environment. Abundant N2 and CO2 also carry ultra-fine Na-salt residue continuously suppressing fire. As a new fire extinguishing technique for use in underground coal mines, SPA shows potential for underground fire prevention. [ABSTRACT FROM AUTHOR]

Rational compositions of a polymer composite material are proposed and technological prerequisites for manufacturing technical products for chemical engineering, based on liquid resol phenol–formaldehyde resins and dispersed fibrous filler manufactured by mechanical processing of the organic waste from fiber production in the pulp and paper industry are evaluated. Methods and parameters of technological stages, including the preparation of raw materials and their mixtures, production of a polymer dispersed filled press material, and hot molding (pressing) products, were determined and tested. Recommendations are given on the hardware and process design of the technological stages of the production of a quality polymer composite material and improvement of its properties. The regularities of changes in the physical and mechanical properties (response on compression, tension, and bending, as well as impact strength and moisture and oil absorption) of the composites with the concentration of dispersed fibrous filler at the recommended thermal pressing parameters (temperature 170 °C, specific pressure 20 MPa, exposure time 1 min/ 1 mm product thickness). Clear evidence is provided showing that the upper limit of the percentage of dispersed fibrous filler in the studied phenolic samples is 40-60%, and at higher percentages the mechanical parameters are strongly deteriorated and the moisture and oil absorptions become much higher than the limits permitted by standards for technical phenolic plastics. The results of the study make it possible to recommend the compositions based on liquid resol phenol–formaldehyde resins and modified fibrous waste from the pulp and paper industry and the hardware and process design for the production of phenolic products of chemical engineering. The developed composites allow homogeneous coloring in various colors (except for white) and imparting to their surface a smooth shiny texture. [ABSTRACT FROM AUTHOR]

Purpose: We have to transform our societies and economic systems towards social, ecological, and economic (holistic) sustainability. Bioeconomy (BE) can contribute to sustainable development by substituting fossil-based products with renewable ones; however, sustainability is not intrinsic to BE. Methods: Therefore, we developed a holistic and integrated life cycle sustainability assessment (HILCSA) method containing 91 indicators, implemented in openLCA, using the Ecoinvent and SoCa database, and addressing 15 out of 17 Sustainable Development Goals. We applied it for the first time to show its capabilities by assessing the holistic sustainability of laminated veneer lumber (LVL) relative to hot-rolled steel beams. Results, discussion: Our results indicate that renewable bio-based construction materials can have a better holistic sustainability than fossil-based products for nearly all indicators, by less stressing the environment, having a less negative impact on society and being economically more efficient. However, fossil-based components of LVL such as phenolic resin are main contributors of negative impacts and should be reduced and replaced. Renewable resources from agriculture and forestry have significant impacts on land use (change). Conclusions: HILCSA demonstrates to be able to provide comprehensive sustainability assessments as well as aggregated results. BE substitutes indeed can improve sustainability; however, sustainability assessments and HILCSA need to be further developed to allow conclusions to be drawn about absolute sustainability of BE. [ABSTRACT FROM AUTHOR]

It is important to examine the long-term durability of glass-kenaf fibre reinforced phenolic resin composites when they are exposed to humid environments or submerged in water. Furthermore, the durability of such composites when immersed in different pH solutions have yet to be examined. As such, this present study examined the use of 4%, 8%, and 12% volume fractions (vfs) of microcrystalline cellulose (MCC) as a filler and reinforcement to improve the properties of glass fibre-kenaf reinforced phenolic resin composites. The flexural strength of these composites was examined both pre- and post-immersion in distilled water (pH 7), seawater (pH 8), and an acidic solution (pH 3) for 60 days. The diffusion mechanism, difussion coefficient, and water absorption concentration were also examined. The difussion coefficient and water absorption concentration occurred post-immersion in distilled water (pH7) and seawater (pH8) while the acidic solution (pH3) resulted in the highest loss of mass and size. Scanning electron microscopy (SEM) of the surfaces of the saturated composites indicated that fibre-matrix interfacial bonding was weak. However, composites that contained a higher vf of MCC exhibited stronger interfacial bonding between the matrix and constituents, thereby, reducing water absorption and diffusion. The flexural strength of the composite pre- and post-immersion was MCC12 > MCC8 > MCC4 > MCC0, in descending order of strength. [ABSTRACT FROM AUTHOR]

The support material for cellulose-insulating paper is usually phenolic resin, which can no longer meet the mechanical characteristics, flame-retardant performance, and heat resistance requirements of insulating paper as the market evolves. In this article, the modified ammonium polyphosphate (APP) particles with excellent flame retardant and hydrophobic properties were prepared by the sol–gel method, which was applied to cellulose paper by compounding them with aqueous boron phenolic resin (BPF). The performance of the insulating paper had been significantly improved by evaluating the various properties of the paper, its breakage resistance and stiffness retention rates were 60.1% ~ 77.5% and 39.9% ~ 50.4%, respectively. With conductivity and breakdown voltage of 8.76 × 10–14 ~ 1.01 × 10–11 S/cm and 8.28 ~ 9.81 kW/mm, respectively. The introduction of Si elements on the surface of APP for surface coating improved the insulation performance of the insulating paper. According to the results of the cone calorimeter, the insulating paper fulfilled the UL-94 standard V-0 level with a maximum LOI value of 32.5%, which was a flame-retardant grade. [ABSTRACT FROM AUTHOR]

Plants can use silicon (Si) as a common element that helps plants recover from environmental stresses. Using Si helps build tolerance to many stresses, illnesses, infections and protects plants against fungus and herbivorous insects. Silica is absorbed by plant roots and then transferred to the plants above-ground components via the transpiration stream. Si deposition in plant tissues promotes stiffness and strength while decreasing water transpiration and abiotic stress. It is found in plant cell walls, lumens, trichomes, intracellular spaces and reproductive organs. Plants contain 0.1–10% silicon by weight. Concentration-based categories include accumulators, intermediates, and excluders. It increases protective chemicals (enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia lyase) and phenolic resins (phytoantitoxins, polylactones). Silicon can regulate plant volatile emissions, which may affect herbivore insects and higher trophic levels. Si accumulation in plants modifies three major plant hormones (jasmonic acid, salicylic acid and ethylene), altering volatile organic compound (VOC) emissions. During pest infestations, soluble Si in plant tissues attracts natural predators and parasitoids and it works as a natural insect repellant and can be easily integrated with other pest management practices. Because silicon leaves no pesticide residues in food or the environment, it is a feasible component of integrated pest management, so the connection between silicon-treated plants and reduced insect damage was discussed in this review. [ABSTRACT FROM AUTHOR]

The anions in the phenol–formaldehyde resin colloid interact with the metal cations in the system to form aggregates with different fractal structures. In this study, Mg2+ and Na+ were studied. At low cationic concentrations, colloid aggregates with the reaction-limited colloidal aggregation (RLCA) mechanism, forming loose aggregates. At high cationic concentrations, colloid aggregates with the diffusion-limited cluster aggregation (DLCA) mechanism, forming dense aggregates. By establishing the triple-layer surface complexation model of phenol–formaldehyde resin, the similarities and differences in interfacial characteristics of phenol–formaldehyde resin under different valence metal cation solutions were explained. The establishment of the triple-layer surface complexation model of phenol–formaldehyde resin is helpful in understanding the change of the aggregation morphology of phenol–formaldehyde resin in the rock gap and groundwater environment, and the change of the colloid interface properties during the co-transport of aggregates and colloidal metal cations. [ABSTRACT FROM AUTHOR]

The contribution introduced a new type of titanosilicate molecular sieve HTS-1-X with high specific surface area, high titanium content, hierarchical pores, hydrophobicity, and reusable by one-step dry gel conversion method using phenolic resin as a hydrophobic reagent. The HTS-1-X catalysts showed good catalytic ability in the propylene epoxidation reaction, and the high specific surface area greatly increased the conversion rate of hydrogen peroxide (H2O2). By controlling the content of phenolic resin, the selectivity of propylene oxide (PO) could reach the optimal value. After five cycles of reusability, the selectivity of PO was still maintained at a high position (88.94%). Through Raman, 13C-MAS-NMR and other characterization methods, the possible preparation mechanism of phenolic resin hydrophobic modification of titanium silicalite-1 was proposed. This research put forwarded a simple and novel operation method to make high-performance and hydrophobic hierarchical porous molecular sieve, making it a highly efficient catalyst that would be widely used in the oxidation of macromolecular olefins. The simple and efficient dry gel conversion method was chosen to prepare titanium silicalite-1 (TS-1) instead of the traditional hydrothermal synthesis method. The hydrophobic carbon source (phenolic resin) was added in the one-step synthesis process, and the hydrophobic hierarchical porous HTS-1-X was successfully synthesized. [ABSTRACT FROM AUTHOR]

The microbiological activity of three types of landfilled foundry wastes, i.e. biologically reclaimed foundry waste (BFW), foundry waste landfilled since the 1990s (LFW) and fresh foundry waste (FFW), was investigated. The wastes originated from a Polish iron and steel foundry which uses organic binders based on phenol–formaldehyde resins and mineral binders to casting production. The physical and chemical properties and dehydrogenase activity (DHA) were determined in the waste samples and local soils. In addition, a pot experiment was performed to determine the effect of the addition of FFW with no microbial activity on soils. Additional correlation analysis was conducted between DHA and other parameters. It was found that biologically reclaimed foundry waste (BFW) showed the highest microbial activity, similar to soils from garden allotments and agricultural fields. The DHA in LFW was about a half lower than BFW. On the other hand, FFW did not show any microbial activity. A pot experiment showed that increasing the percentage of foundry waste relative to soil had a negative effect on DHA, probably as a result of soil dilution rather than the inhibitory effect of contaminants. It was concluded that the optimum addition of FFW to soils is 10% wt, due to the highest value of DHA among the other variants. [ABSTRACT FROM AUTHOR]

In order to keep the microcapsules intact during transportation and storage, the mechanical properties of the microcapsules need to be enhanced, and therefore, we innovatively attached the oxidized carbon nanotubes (CNTs) to the surface of phenolic resin, and CNTs/phenolic resin microcapsules were successfully synthesized by in situ polymerization method. The tests showed that CNTs had been successfully compounded with phenolic resin, and CNTs can effectively improve the mechanical properties of microcapsules with a 16.37% increase in maximum rupture load. This research result was expected to provide positive scientific ideas to solve the problem of early fracture in the airtight wall of the goaf. [ABSTRACT FROM AUTHOR]

The purpose of this paper lies in the preparation and utilization of phenolic resin hollow microspheres to enhance the induced carbonization performance of polymer materials and endow higher fire safety. PHM (phenolic resin hollow microspheres), CPHM (carbonized phenolic resin hollow microspheres), and CAPHM (carbonized phosphorylated phenolic resin hollow microspheres) were used as fillers in thermoplastic polyurethane elastomer. With the incorporation of 4 wt.% CPHM, as compared to pure TPU, the peak heat release rate (pHRR), total smoke release (TSR), and the peak CO release rates are decreased by 64.4%, 37.9%, and 86.2%, respectively. Simultaneous enhancement in flame retardancy, smoke suppression, and toxicity reduction is attributed to the formation of a compact residual layer in the polymer matrix, which significantly retards the dispersion of combustible gas, smoke particles, and toxic gas from the underlying substrate. Such outstanding characteristics make carbon microspheres a promising candidate for high fire safety polymers. [ABSTRACT FROM AUTHOR]

In this study, a commercial kraft lignin (KL) was used as the raw material to prepare phenolic resin (PF) based on a detailed analysis of its molecular structure. To further increase the viscosity of the phenolic resins and improve their environmental performance, demethylated and hydroxymethylated KL (DKL and HKL) were also prepared and used to produce DKLPF and HKLPF. Compared with the methoxy content of KL, that of DKL was lower by 39.34%, and the alcoholic hydroxyl contents of HKL were higher by 59.39%. Therefore, the increased active sites on the benzene ring of DKL promote the hydroxymethylation reaction, and HKL adds more methylol groups, which is more conducive to the condensation reaction to produce PF. The synthesis process and properties of the lignin-based PF with high phenol substitution rates were investigated. The results showed that the maximum substitution rates of KL, DKL, and HKL to replace phenol to prepare phenolic resin were 70%, 50%, and 30% (w/w). The viscosity, free formaldehyde content, and other important indices of LPF meet the requirements of the GB/T14732-2017 standard. Besides, as the substitution rate of phenol by lignin increases, the viscosity of DKLPF and HKLPF performance is higher. When the 30% (w/w) phenol was replaced by lignin, the adhesive strengths of KLPF, DKLPF, and HKLPF all reached the maximum, and the trend of adhesive strengths was KLPF < DKLPF < HKLPF. [ABSTRACT FROM AUTHOR]

Electrothermal materials can easily and controllably convert electric energy into heat energy, and are widely used in many electrothermal fields. In this paper, a series of conductive pastes were simply prepared by ball milling, and their rheological and electrothermal properties were studied. Phenolic resin was used as curing agent of epoxy resin and rheological modifier, which could make the paste have very good printing applicability. Ultrafine carbon(UC) powder has excellent dispersion effect. Sheet carbon materials such as graphite powder(GP), graphite nanosheet(GS) and graphene(GE) would improve the performance of paste using only UC as conductive filler. It was proved that GE with the smallest thickness has the most obvious lifting effect. UC was gathered around the graphene sheet, as a bridge between graphene sheets. GE could also be connected with each other to build a more effective and denser conductive path. The electrothermal film could reach 199°C under 30 V voltage, increasing by 254.7% compared with the electrothermal film with only UC as conductive filler. The electrothermal film had a short response time, good recyclability and excellent flexibility. The electrothermal film also had certain electromagnetic shielding efficiency. The electromagnetic shielding efficiency SE could reach about 20 dB at 30–1500 MHz, and the ratio of field strength before and after attenuation SE% could reach 97% +. This electrothermal film has simple preparation process, good printing applicability, controllable film resistance, excellent flexibility, fast response speed and good recyclability. It is suitable for large-scale preparation and has broad application prospects in many scenarios. [ABSTRACT FROM AUTHOR]

The fabric composites, which are always used as a self-lubricant liner, also work as a forming lubricant during the assembly of the spherical plain bearings. Different from previous published works, the tribological behavior of polytetrafluoroethylene (PTFE)/Nomex/phenolic composite lubricant under cold forming condition in the bearing assembly process was investigated in details. A hybrid PTFE/Nomex fabric composite with a volume fraction of 1:3 coated with phenolic resin matrix sticking on a stainless steel 05Cr17Ni4Cu4Nb was prepared for the study. The ring with boss compression test (RCT-B) was selected as a tribometer, and a specific group of calibration curves were constructed by simulations with various friction factors. To obtain favorable tribological performance of the fabric-composite lubricant, the preparation parameters of the testing workpieces, including number of sandblasting cycles, curing time, and curing temperature, were optimized. To explore the lubricate limit of the optimal fabric-composite lubricant, the RCT-B tests with much larger reduction in height under much higher press speed were furtherly carried out. The failure modes of the fabric-composite lubricant, mainly including peel off, hysteresis, and delamination, were revealed. The failure mechanisms and the applicable limitation of the fabric-composite lubricant were finally discussed. [ABSTRACT FROM AUTHOR]