Search

Paper‐based friction materials with phenolic resin as the matrix are prone to thermal damage under harsh working conditions easily leading to materials failure. To satisfy the requirements of high speed and heavy load service situations, paper‐based friction materials with different polyimide resin content were prepared by wet forming technology to reveal the effect of polyimide resin on the properties of composites. And a paper‐based composite with phenolic resin was used for comparison. Results show that compared with the phenolic composite, tensile strength, and shear strength of the polyimide composite were increased by 50.5% and 36.4%, respectively. Due to the strong hydrogen bond in the imide ring of polyimide, the temperature of the polyimide composite at 2% weight loss was 292.7°C, which was 106.3°C higher than that of the phenolic composite. Moreover, the wear rate was reduced by 30.3% because the friction transfer film was produced during friction. To sum up, polyimide resin has the potential to replace phenolic resin under the condition of high speed and heavy load. Besides, the composite with polyimide resin content of 40.0 wt% demonstrated the best wear resistance and considerable strength attributed to the best interface combination. This research lays a theoretical foundation for the application of polyimide resin to paper‐based friction materials. [ABSTRACT FROM AUTHOR]

In this study, the effects of NBR polarity and organoclay addition on the curing, rheological, mechanical, and thermal properties of an NBR/phenolic resin blend were investigated. The samples were prepared using a two-roll mill. The results showed that rheological and tensile properties improved due to the good distribution of nanoparticles, as well as the good compatibility of nitrile butadiene rubber with phenolic resin. The addition of 1.5 phr of nanoparticles to blends containing 33% and 45% acrylonitrile increased the curing torque difference by approximately 12% and 28%, respectively. In addition, the scorch time and curing time decreased in nanocomposites. Adding nanoparticles also increased the viscosity. The addition of phenolic resins and nanoparticles has a similar trend in modulus changes, and both of these factors increase the stiffness and, consequently, the elastic and viscous modulus of the specimens. Adding 1.5 phr of organoclay increased the tensile strength of the blends by around 8% and 13% in the samples with low and high content of acrylonitrile, respectively. Increasing the temperature of the tensile test led to a reduction in the tensile properties of the samples. Tensile strength, elongation at break, modulus, and hardness of the samples increased with increasing organoclay content. In addition, with increasing nanoparticle concentration, the samples underwent lower deterioration in tensile strength and Young's modulus at different temperatures compared to the blends. In the samples containing 1.5 phr of organoclay, the thermal decomposition temperatures were enhanced by around 24 and 27 °C for low and high acrylonitrile content. [ABSTRACT FROM AUTHOR]

Industrial lignin is oxidized by H2O2 and (NH4)2S2O8 under mild conditions and used in lignin-phenolic resin adhesives. After H2O2 treatment, the molecular weight of lignin is reduced by 9.8%,the content of phenolic hydroxyl group is increased by 27.46%,and the reactivity is improved; after treatment with (NH4)2S2O8,the content of lignin methoxy group is reduced by 9.92%,and the phenolic hydroxyl group is increased by 12.15%.Reactivity with formaldehyde increase. Under the same substitution rate, the free phenol and free formaldehyde content of the adhesive prepared by H2O2, (NH4)2S2O8 treatment of lignin decreased, and the bonding strength increased. Among them, (NH4)2S2O8treatment of lignin to prepare adhesives has a significant increase in bonding strength. Under 140 ℃ and 1.20 MPa hot pressing conditions, the bonding strength of L3PF-50% reached 1.80 MPa, an increase of 35.34%.Under 160 ℃ and 1.60 MPa hot pressing conditions, the bonding strength of L3PF-50% reached 1.94 MPa, an increase of 33.79%,and the strength of L3PF-80% increased by 29.63% to 1.40 MPa. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work, octamercapto polyhedral oligomeric silsesquioxane (POSS-8SH) and octaphenol polyhedral oligomeric silsesquioxane (POSS-8Phenol) were successfully synthetized. POSS-8Phenol was added into the synthesis process of liquid thermoset phenolic resin (PR) to obtain POSS-modified phenolic resin (POSS-PR). Chemical structures of POSS-8SH, POSS-8Phenol, and POSS-PR were confirmed by FTIR and 1H-NMR. TG and DTG analysis under different atmosphere showed that char yield of POSS-PR at 1,000°C increased from 58.6% to 65.2% in N2, which in air increased from 2.3% to 26.9% at 700°C. The maximum pyrolysis temperature in air increased from 543°C to 680°C, which meant better anti-oxidation properties. XRD results confirmed both POSS-8Phenol and POSS-PR-generated crystalline SiO2 in air, which could explain the improvement of anti-oxidation properties. SEM showed that the POSS-PR had phase separation during curing process. Finally, carbon fiber fabric-reinforced POSS-PR (C-POSS-PR) was prepared to verify the anti-oxidation properties of POSS-PR.

Potassium ion batteries (PIBs) have attracted considerable attention owing to their unique advantages. Nevertheless, the large radius of potassium ions and their sluggish kinetics hinder the further development of potassium ion batteries. In this study, mesoporous hard carbon nanospheres (PCN- x , where x corresponds to pyrolysis temperatures of 700 ℃, 800 ℃, and 900 ℃) have been successfully prepared from a facile hydrothermal and pyrolysis processes at different temperatures of phenolic resin precursor. The obtained PCN- x materials offer several advantages, including abundant active sites, favorable interlayer spacing (0.4113 nm), high specific surface area (574.7202 m2 g−1), and exceptional structural stability. These merits collectively contribute to enhancing the stability of potassium ion intercalation/deintercalation behavior and provide a high pseudocapacitive capacity. While used as anode materials for PIBs, these materials exhibit remarkable battery performance, including a superior initial charge capacity of 395.2 mAh g−1 at the current rate of 100 mA g−1, exemplary rate performance (209 mAh g−1 at 5 A g−1), and outstanding cycle stability, retaining a capacity of 249 mAh g−1 after 1000 cycles. The present work introduces a low-cost and straightforward method for the preparation of anode materials of PIBs and provides valuable insights into the energy storage field. [Display omitted] • Hard carbon nanospheres were prepared through annealing of phenolic resin precursor. • The obtained PCN-700 materials offer favorable interlayer spacing and high specific surface area. • PCN-700 presented superior initial charge capacity, excellent rate performance and outstanding cycle stability. [ABSTRACT FROM AUTHOR]

Resorcinol-formaldehyde (RF) aerogel materials exhibit remarkable properties such as low density, ablation resistance (high residual carbon rate), easily regulated pore structure and low thermal conductivity, making them promising for applications in adsorption, medicine and aerospace, among others. However, since their inception, RF aerogels have suffered from disadvantages such as brittleness and long preparation cycles, which have severely limited their widespread use. In order to improve the mechanical properties of RF aerogels, this paper presents a new synthetic route for obtaining strong elastic properties without introducing additional fiber reinforcement. Here, a lightweight, compressible, elastic resorcinol-formaldehyde aerogel with cobalt-ligand-enhanced cross-linked skeletons was prepared by sol-gel and freeze-drying methods using an alkali metal salt (cobalt (II) acetate) as a cross-linking agent and sodium acetate as a catalyst. The coordination of metal ions (Co2+) with resorcinol resulted in the formation of a structure analogous to a metal-phenolic network (MPN), which altered the crosslinking mode and degree of crosslinking of the RF aerogel. This process led to the thickening of the skeletal structure of the sample. Concurrently, a multilayered pore structure was generated within the interior under the appropriate pH conditions, which contributed to the strengthening of the skeleton of the samples and a reduction in thermal conductivity. The obtained RF-Co aerogel can withstand 68.6 % compression change without fracture and shows good elastic deformation at 35 % compression rate, while the aerogel exhibits low thermal conductivity (0.039 W (m K)−1) and low density (0.09 g cm−3). [ABSTRACT FROM AUTHOR]

The eco-friendly extraction of lithium from liquid lithium minerals with low energy consumption is a research focus due to the expansion of new energy industries. Herein, a transition metal ferrocyanide electrode prepared by a novel in-situ polymerization asynchronous conversion method with K 2 NiFe(CN) 6 as the active ingredient was developed for membrane-free electrochemical extraction of lithium. The structure and electrochemical properties of the electrode were studied in detail using various structural characterization and electrochemical testing techniques. Following structural regulation and hydrophilicity improvement, the insertion capacity of the electrode for only 100 mg·L−1 K+ reached 4.95 mg·cm−3 after 30 min, almost double that of the electrode prepared using the conventional coating method. The high selectivity of the electrode makes it an effective counter electrode for constructing an electrochemical system with a FePO 4 electrode for membrane-free extraction of Li+ from geothermal water. The cumulative extraction rate of Li+ reached 70% after just five consecutive cycles, and the electrode performance did not change significantly after 50 cycles. The electrode developed in this work exhibited a high capacity and exceptional stability, making it an ideal candidate as a counter electrode for selective extraction of Li+ by environmentally friendly electrochemical technology. [Display omitted] • A novel K 2 NiFe(CN) 6 electrode was prepared for electrochemical extraction of Li+. • Phenolic resin was used as the supporter instead of the traditional coating method. • In-situ polymerization asynchronous conversion method was developed. • The Li+ in geothermal water was extracted by the membrane-free electrochemical method. [ABSTRACT FROM AUTHOR]

• Phenolic resin-derived hard carbon (PRHC) spheres are synthesized from 700 to 1000 °C. • Both Li ions and Na ions storage mechanisms of PRHCs are studied. • Adsorption energy of Li/Na ions on graphene with different oxygen defects iscalculated by theoretical calculations. • The optimized-PRHCs delivers 151 mAh g-1 at 1.0 A g-1 after 200 cycles for Na ion battery. Batteries or electrochemical energy storage devices are dependable substitutes for electrical energy storage systems that rely on fossil fuels and are essential in reducing greenhouse gas emissions. As a result, one of the most promising sustainable materials for energy storage is hard carbon (HC). We propose both Li and Na ions storage mechanisms of hard carbon spheres derived from phenolic resin (PRHCs). The characterization and electrochemical analyses of the PRHCs synthesized at different temperatures were performed. The PRHCs at various sintering temperatures from experimental and theoretical calculations were investigated. The investigation highlighted the role of C=O in determining the electrochemical performance of PRHCs, as well as the relationship between the ratio of micropores and mesopores and Na/Li ions' storage mechanisms. DFT calculations showed an enhancement in Na/Li adsorption with the existence of C=O in the graphene. The electrochemical performance of PR800, which was obtained after sintering at 800°C, demonstrated the highest reversible capacity of 151 mAh/g after 200 cycles at 1.0 A/g. Both capacitive-controlled and diffusion-controlled mechanisms were found to be significant in Na ion transfer, according to the electrochemical investigation. The as-synthesized hard carbon exhibited potential as anode materials for both Na and Li ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Phenolic resin (PR) composites are widely utilized as thermal protection materials for high-speed aircraft, where their protection mechanisms have been investigated in earlier studies. However, it remained indistinct about the evolution behavior of the outermost surface and its subsequent effects on the ablation performance. Herein, this work re-investigated the morphological transformation and chemical conversion on the outermost surface of a silica fiber-reinforced PR board after ablation by means of combined experimental characterizations at micro- and nanoscale (SEM, TEM, Raman spectroscopy, XRD, XPS) and computational study (ReaxFF-based molecular dynamic simulation). For the first time, our study revealed that its outermost ablated surface demonstrated a distinct evolution behavior in terms of both the in-situ formation of "self-protective" graphitic layer and the radial redistribution of surface carbonaceous substances with different degrees of graphitization, leading to varied ablation resistance along the radial direction of the PR board. In addition, the computational study investigates the ablation-induced graphitization and its influence on the ablative resistance of PR surface. It indicated that, at equivalent energy flux density, PR with graphitized structures exhibited improved thermal protection performance, which can be attributed to decreased thermal conductivity and increased density, leading to a reduced ablation recession rate. Such revelation provides an alternative route in the design of PR-based ablative materials with enhanced ablation resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

Wood-based electrodes are widely used in supercapacitors due to their renewable and three-dimensional self-supported properties. Low space utilization of wood-based electrodes seriously restricts its practical applications. In this paper, a wood/phenolic resin composite was designed, which can effectively enhance the space utilization of wood and ensure a hierarchical porous structure. The prepared balsa wood/phenolic resin composite-derived electrode obtained a high areal capacitance (8169 mF cm–2), which is 954 % of pure balsa wood-based electrode. Moreover, the assembled symmetrical supercapacitor device exhibits outstanding electrochemical performance, displaying a high areal capacitance of 3.3 F cm–2, and a competitive volumetric energy density of 2.88 mWh cm–3. More importantly, this design has been successfully used to prepare various species wood-derived electrodes. Therefore, as a general strategy, which gives a novel idea for the design of wood-derived electrodes and may affect other fields using wood-based materials. [Display omitted] • A simple method was used to enhance the space utilization of wood-based electrodes. • This strategy has been successfully applied to a various of wood. • The assembled SSC device delivers competitive areal energy density of 0.46 mWh cm–2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel phenolic resins with phosphazene derivative (CHPP) were synthesized. • The prepared phenolic resins reveal high thermal stability and char yield. • The line ablation rate of prepared phenolic resins was as low as 0.0020 mm/s. • The CHPP could promote the formation of char yield during ablation and carbonization. A novel phenolic resin with combined hydroxymethyl-substituted phosphazene unit as a part of cured network was prepared which exhibited excellent thermal properties and ablation resistance. The novel phenolic resin was synthesized via copolymerizing from hexa (4-hydroxymethylphenoxy) cyclotriphosphazene (CHPP), phenol and paraformaldehyde. The CHPP contains abundant –CH 2 OH groups, which can be a part of phenolic resin network through condensation reactions between the –CH 2 OH groups and active hydrogens on benzene rings of phenolic resins. The optimal curing temperature for the modified phenolic resins was determined using the non-isothermal DSC method. The ablation resistance was investigated using the oxyacetylene flame method. The char yield and linear ablation rate of the modified phenolic resins are 71.3 % and 0.0020 mm/s, respectively. The ablation resistance of the novel resin is significantly improved, compared with other phenolic resin composites. The modification method for the phenolic resin provides a novel pathway to improve the application prospects of phenolic resins in the field of thermal protective materials. [ABSTRACT FROM AUTHOR]

With the development of the new generation space vehicles, traditional phenolic resin (PR)-based coatings are no longer able to meet the increasingly harsh thermal environment. There is an urgent need to develop higher performance PR to ensure the flight safety of aircraft. Therefore, in this work, a novel hyperbranched polysiloxane containing Si-O-Zr bond was synthesized and then introduced into PR to develop homogeneous silicone/phenolic hybrid resin coatings. The TG results indicate that the introduction of Si-O-Zr bonds significantly improves the heat resistance of silicone. During ablation, the hyperbranched polysiloxane will undergo a ceramization to produce SiO 2 and ZrO 2 particles, both of which will subsequently generate a highly viscous Zr-Si-O glassy phase as anti-ablation layer. With the fluidity and self-healing properties, it can fill the gaps of the carbon layer and cover the surface of the carbon layer, giving the hybrid resin excellent ablative resistance. The linear ablation rate of the hybrid resin can be as low as 0.003 mm/s, which is an 80 % decrease compared to pure PR. The synthesized hybrid resin is expected to act as superior thermal protection coatings for the next generation of spaceflight. [Display omitted] • A novel hyperbranched polysiloxanes containing Si-O-Zr bond was synthesized. • The prepared silicone/phenolic hybrid resins showed homogeneous structure without phase separation. • Hyperbranched polysiloxanes are ceramized during ablation to form a protective Zr-Si-O glass phase. [ABSTRACT FROM AUTHOR]

Abstract Plywood panel has a promising market in Wood Frame Construction System. Like any wood-based product, it can suffer deterioration, and preservative treatment is imperative. The preservative treatment can be done directly on a pressed panel - a conventional method that supposedly causes a decrease in physical-mechanical performance - or incorporated into the production process, by the previous treatment of veneers to develop panels with durability and quality. We compared the performance of these two processes. Panels were produced with Pinus taeda L., using 360 g m-2 of phenolic adhesive in a double line, a pre-pressing and hot pressing for 20 minutes under 1.2 MPa pressure and 130°C and treatement on veneers and panels with CCA-C. Tests followed Brazilian standards. Panels with previous treatment had lower water absorption and swelling. Preservation of the veneers also promoted higher retention levels and better penetration of preservatives. Both treatments did not affect the mechanical performance.

• Identification of various manifestations of spheroidization. • The occurrence of balling exhibits a robust correlation with process parameters. • Establishment of the processing window for phenolic resins. • Molding phenolic resin parts using SLS technology. The balling phenomenon commonly manifests in the selective laser sintering (SLS) 3D printing of phenolic resin materials, significantly impacting molding outcomes and performance. The study determined the optimal preheating temperature of phenolic resin using differential scanning calorimetry (DSC). The correlation between the occurrence of the balling phenomenon and process parameters was investigated through single fusion channel and single-layer sintering tests. Findings indicated that a preheating temperature below the glass transition temperature could induce the balling phenomenon regardless of the process parameter. The optimal preheating temperature was identified as 65 °C, reducing the likelihood of slating and facilitating easier processing of phenolic resin. Two distinct balling phenomena were observed in the single fusion channel experiments, correlating with the depth of the sintering melt pool. In the single-layer sintering tests, the balling phenomenon resulted in the formation of reticulation and large balls. Specifically, achieving well-formed sintered layers was more feasible with a scanning spacing of 0.25 mm. The study offers crucial recommendations for parameter adjustments and temperature control to optimize the SLS 3D printing of phenolic resin materials, aiming to enhance molding outcomes and overall performance. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is a typical endocrine disruptor, which can be used as an industrial raw material for the synthesis of polycarbonate and epoxy resins, etc. Recently, BPA has appeared on the list of priority new pollutants for control in various countries and regions. In this study, phenolic resin waste was utilized as a multi-carbon precursor for the electrocatalytic cathode and loaded with cobalt/nitrogen (Co/N) on its surface to form qualitative two-dimensional carbon nano-flakes (Co/NC). The onset potentials, half-wave potentials, and limiting current densities of the nitrogen-doped composite carbon material Co/NC in oxygen saturated 0.5 mol H 2 SO 4 were −0.08 V, −0.61 V, and −0.41 mA cm−2; and those of alkaline conditions were −0.65 V, −2.51 V, and −0.38 mA cm−2, and the corresponding indexes were improved compared with those of blank titanium electrodes, which indicated that the constructed nitrogen-doped composite carbon material Co/NC was superior in oxygen reduction ability. The catalysis by metallic cobalt as well as the N-hybridized active sites significantly improved the efficiency of electrocatalytic degradation of BPA. In the electro-Fenton system, the yield of hydrogen peroxide generated by cathodic reduction of oxygen was 4.012 mg L−1, which effectively promoted the activation of hydroxyl radicals. The removal rate of BPA was above 95% within 180 min. This work provides a new insight for the design and development of novel catalyst to degrade organic pollutants. [Display omitted] • Carbon materials prepared from phenolic resin waste as electrocatalytic cathodes. • Removal rate of BPA was above 95% within 180 min. • In situ activation of H 2 O 2 generated by cathodic reduction using Co. • Graphite-type nitrogen and pyridine-type nitrogen form catalytic sites. [ABSTRACT FROM AUTHOR]

The study demonstrates that phenol-formaldehyde (PF) resin, commonly used for lignocellulosic composites, can become electroconductive when modified with graphene nanoplatelets (GNPs) while still serving as an effective adhesive for particleboard production. The PF resins enriched with various amounts of GNPs were tested for viscosity, gel time, and thermal stability, followed by electrical conductivity measurements for GNP-enriched resins applied to several lignocellulosic surfaces of varying wettability. These tests showed that the optimum weight percentages of GNP at which the resins maintain both the electrical conductivity and process parameters, enabling the formation of particleboard, amount to 18.5%. Consequently, a prototype of electroconductive particleboard was created and evaluated for bending strength (EN 310: 1993), modulus of elasticity (EN 310: 1993), tensile strength (EN 319: 1993), thickness swelling (EN 317: 1993), water adsorption (PN-76/D-04234) and formaldehyde emission (EN ISO 12460–5:2015). Impressively, the panels achieved a conductivity of 320 Ω m, indicating their potential use as resistive heaters and other applications in the Internet of Things (IoT) area. Simultaneously, the GNP-enriched panels showed formaldehyde emission well below the threshold set by the standards and exhibited mechanical properties that in most cases met the criteria for use in furniture and interior design. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bio-based resin nanospheres were prepared using tannin and furfural as feedstock. • The size range of TFR nanospheres can be adjusted from 280 to 1430 nm. • TFR have strong adsorption, reduction and chelation capacity for Ag+/Ag NPs. • TFR@Ag show excellent catalytic activity in treating dye-containing wastewater. Phenolic resin (PR) nanomaterials, which serve as excellent carriers for precious metals, are typically synthesized via the cross-linked reaction of phenol and formaldehyde, and both are toxic. Therefore, replacing them with whole biomass-based materials is an attractive alternative; however, it has proven to be a significant challenge. In this study, we successfully prepared versatile Ag-based resin nanocomposites (referred to as TFR@Ag) by utilizing whole biomass-based tannin and furfural as raw feedstock. The resulting TFR nanospheres exhibited high stability and uniformity, with tunable sizes ranging from 280 to 1430 nm by adjusting the amount of ammonia used in the synthesis process. Importantly, compared to traditional PR nanospheres, the novel and environmentally friendly TFR nanospheres possess abundant phenolic-OH groups that significantly enhance their adsorption, reduction and chelation capacity for Ag+. The highest loading amount of silver nanoparticles (Ag NPs) achieved was up to 60.3 wt% with a size of only 10.6 nm. The as-obtained TFR@Ag nanocomposites demonstrated excellent catalytic activity in treating typical hazardous dye-containing wastewater. As catalyst, the 0.4 mg TFR@Ag were capable of achieving full reduction of 2 mL 40 mg·mL−1 methylene blue (MB) and methyl orange (MO) in just one minute, exhibiting reaction rate constants of 1.71 min−1 and 2.40 min−1, respectively. Moreover, as antibacterial agents, the TFR@Ag nanocomposite effectively inhibited the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with a bacterial inhibition rate close to 100 %. This work presents a new strategy for green synthesis of multi-functional Ag-based nanocomposites that hold great potential in various fields such as catalysis, nanomaterials science and biomedicine. [ABSTRACT FROM AUTHOR]

Silicon/phenolic hybrid resins are one of the most commonly used materials for thermal protection. However, the weak ability of SiO 2 generated by silicone during ablation to resist the impact of high-speed hot gas flow hinders further improvement of the performance. Therefore, in this work, the ultrahigh-temperature ceramic elements Zr4+ and Hf4+ were integrated into hyperbranched polysiloxanes in the form of coordination bond and then introduced into phenolic resin (PR), obtaining hybrid resin with excellent ablative resistance. During ablation, Zr4+ and Hf4+ will first undergo ceramization, producing ZrO 2 and HfO 2. Subsequently, they will undergo a solid solution sintering reaction to produce complex-phase ceramic particles (Zr x Hf 1-x)O 2 , which are embedded in the SiO 2 liquid film and provide excellent pinning effect. This gives the hybrid resin excellent ablation resistance, whose linear ablation rate can be as low as 0.038 mm/s, a 58 % decrease compared to pure PR. This work not only provides a new pathway for ceramization through metal ion coordination bonding, but also provides a new way to prepare high-performance TPS materials. [Display omitted] • Zr4+ and Hf4+ were successfully introduced into hyperbranched organosilica through the lone electron pair provided by C=O. • Silicon/phenolic hybrid resin with a unique nano-bicontinuous phase structure was produced. • The coordinated Zr4+ and Hf4+ can undergo in-situ ceramization and solid solution sintering reaction to produce (Zr x Hf 1-x)O 2. • (Zr x Hf 1-x)O 2 can perform an excellent pinning effect and confer excellent ablation resistance to the hybrid resin. [ABSTRACT FROM AUTHOR]

The requirements for long-term stability and thermal performance of resin-based coating materials are gradually increasing with the development of aerospace industry. As a low-toxicity aldehyde, terephthalaldehyde (TPA) with aromatic ring structure and high reactivity is an ideal formaldehyde substitute for synthesizing high thermal stability phenolic resins and coating candidate. In this work we provided a strategy for the synthesis of ferrocenecarboxaldehyde (Fc) in-situ modified TPA-phenol resin (PTPA-Fc), obtaining resin products with high glass transition temperatures at 302 °C. The non-isothermal curing process and activation energy changes of resins with different TPA-phenol ratios were further investigated. It was found that the highest cross-linking density of resin was achieved when TPA/phenol was 0.5, with the initial decomposition temperature (T 5%) reached 378 °C. Afterwards, carbonyl iron powder (CIP) filled PTPA-Fc microwave absorbing coating was prepared. Due to the improved oxidation resistance, composite based on PTPA-Fc had an effective bandwidth of 3.1 GHz (14.5–17.6 GHz, thickness 3 mm) after 100 h heat treatment at 250 °C and could still cover the 9.5–18 GHz absorption band (with RL ≤ -5 dB) with 5 mm matching thickness, reflecting a good long-term thermal stability. [Display omitted] • A strategy for the synthesis of ferrocenecarboxaldehyde (Fc) in-situ modified TPA-phenol resin (PTPA-Fc) was provided. • PTPA-Fc exhibited outstanding thermal properties, with a Tg of 302 °C, a T 5% of 378 °C and a pyrolysis yield of 69.7 % at 800 °C. • CIP-PTPA-Fc with excellent long-term oxygen-thermal stability could effectively protected CIP absorber from oxidation. • CIP-PTPA-Fc coating had an effective bandwidth of 3.1 GHz after 100 h heat treatment (250 °C). [ABSTRACT FROM AUTHOR]

• Utilizing boratrane yields a uniform BO4 structure in the modified reins. • Boratrane and silatrane enable the high-loading silicon and boron contents. • Carbonized resins result in the formation of boron carbides (B 4 C and B 8 C). • The obtained boron carbides exhibit the presence of Lewis acid sites. • The CO 2 absorption capacities for 3BPR and 3B5SiPR are 0.475 and 0.518 mmol/g. In this study, we present an innovative and cost-effective method for the preparation of phenolic resin (PR) containing boron and silicon (BPR and BSiPR) using boratrane and silatrane. Through a one-pot synthesis via a sol-gel process, 3BPR and 3B5SiPR are successfully synthesized, utilizing boratrane and silatrane as the sources of boron and silicon. Our results demonstrate the effective introduction of boron and silicon elements into the PR matrix through the formation of BO 4 (borate) and SiO 4 (silicate) structures, as evidenced by C ph -O-B and B-O-Si linkages. Notably, the utilization of boratrane in the synthesis of 3BPR leads to the formation of a uniform structure of BO 4 , as confirmed by 11B-NMR analysis. Furthermore, the resulting resins exhibit an improved char yield of 72 % at 900 °C. The formation of borate and silicate species effectively reduces the content of phenolic hydroxyl groups, thus contributing to a decrease in weight loss during the carbonization process. Additionally, the migration of boron and silicon into the carbon structure promotes the formation of B 4 C and B 8 C crystal structures, resulting in the carbonization of resins and the formation of a graphene-like structure, as confirmed by Raman spectroscopy, which exhibits a broad 2D-band. The obtained carbon materials possess both Lewis acid and basic sites. The presence of Lewis acid sites was characterized through pyridine-adsorbed FTIR, while the Lewis basic sites and CO 2 absorption were examined via TPD-CO 2 analysis. The CO 2 absorption capacities of 3BPR and 3B5SiPR were found to be 0.475 and 0.518 mmol/g, respectively. [ABSTRACT FROM AUTHOR]

Due to its inferior properties, oil palm wood (OPW) extracted from the inner layer of the oil palm (Elaeis guineensis) trunk, referred as inner OPW in this study, is frequently regarded as a waste. Phenolic resin treatment and lamination of inner OPW with other hardwoods may be an excellent way to improve the properties of the inner OPW. In this study, inner OPW were treated with two different concentrations (15% and 20%) of low molecular weight phenol formaldehyde resin (LmwPF) and compressed at different compression ratios (10%, 20%, and 30%). The physical and mechanical properties of the modified inner OPW’s were evaluated according to British Standards (BS) 373: 1957. The results revealed that inner OPW treated with the highest compression ratio (30%) and resin concentration (20%) exhibited the highest weight percent gain, polymer retention and density. In the following phase of the research, the treated inner OPW was used as the core layer in the fabrication of a three-layer laminated compreg hybrid composites, with untreated and treated sesenduk (Endospermum diadenum) wood serving as the face and back layers. The compression ratios of 10% and 20% and resin concentrations of 10% and 20% were used in this phase of study as laminated boards made with 30% compression ratio failed. The findings showed that resin concentration had a significant impact on both the inner OPW and the laminated compreg hybrid panels. Markedly, higher resin concentrations (20%) resulted in improved physical properties, i.e., thickness swelling and water absorption, as well as enhanced mechanical properties (modulus of rupture and modulus of elasticity). Although compression ratios had no significant effect on the properties of the laminated products, those compressed at higher compression ratios (20%) performed slightly better than the panels compressed at lower compression ratios (10%).

Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Natural fiber–reinforced polymer composites offer many advantages over conventional composite materials, such as availability, low cost, inexpensive, lightweight, and high specific mechanical properties. However, the applications of these materials are still limited due to the challenges in achieving a good interface between the fibers and matrix. This is highly influenced by the fiber surface characteristics and the polymer matrix properties. Therefore, in this study, the surface characteristics of ramie fibers were modified using low-pressure plasma treatment in order to improve their interface to the phenolic resin. Furthermore, the effects of using two different curing cycles (acid cure and thermal cure) on the properties of short ramie fiber-phenolic composites were also investigated. A new method for making mats of random short ramie fibers was developed and used for the fabrication of composites containing plasma-treated fibers. The flexural properties of all composites were tested and the obtained fracture surfaces were investigated using LV-SEM. The results indicate that both plasma treatment and cure cycle conditions influence the fiber–matrix interface and consequently the flexural properties of the composites. [ABSTRACT FROM AUTHOR]

Effective permeability of a porous carbon composite used as thermal protection system on space capsules is computed using the direct simulation Monte Carlo technique. The microstructure of the carbon composite is synthetically generated using an in-house code. Permeabilities obtained using synthetic microstructures of the precursor (carbon fibers) are compared with two independent experimental dataset, and good agreement is observed. It is conclusively shown that the difference in permeability values between the two experimental datasets arose from the variations in the sample density. An approach to digitally infuse resin into the precursor is proposed. Comparison of the permeability for the full composite (carbon fibers with resin) with experimental data resulted in errors within 7.5%, indicating that representative microstructures generated digitally can be used to compute and predict effective permeability of porous carbon composites. Simulations of Ar and air permeating through the full composite are performed, and an intrinsic material permeability (Ko) of 1.866×10-11 m² and a Klinkenberg constant (b*) of 5.655×10-8 that is only dependent on the temperature and the molecular weight of the gaseous species are obtained. It is shown that this new generalized relation could be used for other gases such as CO and CO2. [ABSTRACT FROM AUTHOR]

Improving the traction of an agricultural tractor on the field increases its working efficiency and capacity. Heavy work, like plowing, entails high levels of tire slip, which is directly related to power loss when the transmission of drawbar pull is required. Accordingly, it is possible to hypothesize that a tire with a higher traction capability could increase the working efficiency of the machine. The natural evolution for measuring the geometrical parameters of tires has led to the consideration of three-dimensional (3D) footprints since the distribution of the vertical stresses at the soil-tire interface may be highly non-uniform. In this study, the data acquired from 3D footprints of 10 sets of tires underwent processing along with the data from drawbar tests carried out with the same tires on soil terrain at different slip ratios. Subsequently, artificial intelligence multivariate methods based on artificial neural networks allowed traction prediction and verified the importance that the acquired geometrical parameters have on the measured drawbar pull. The study confirmed the correlation of the geometrical parameters of the 3D tire footprint with the drawbar pull and the results of the artificial intelligence modelling underlined the impact of these acquisitions. However, further work that considers various lug geometries is required to extend the generalizability of the studied methodology. [ABSTRACT FROM AUTHOR]

Phenolic resins are in-organic polymers with properties that make them high-strength binders with great potential for modification. The base-catalyzed phenol-formaldehyde resins provide the desired hardness to the core avoiding sand slipping on the surface. A modified resol type phenolic resin is developed for this study with minimum ingredients to compare it with existing recipes in the literature. A batch of cores was prepared with the standard 1-inch cross-section briquettes (dog-bone) with modified resol and cured through hot-curing process. Hardness and ultimate tensile strength values of these cores were compared with previous data present in literature. The average hardness as well the tensile strength from modified resol was higher than the cores from previous hot coating resol recipes and the gas-set cores present in the literature. Furthermore, the surface roughness of the cores was examined through Atomic Force Microscopy (AFM), and the ten-point height (Rz) value was lower than existing recipes. [ABSTRACT FROM AUTHOR]

This study included the preparation and tribo-characterization of Calotropis gigantea (CG) fiber reinforced CNT modified phenolic resin composites. Composites were prepared with varying contents (0.25, 0.5, 1 and 2 wt%) of multi-walled carbon nanotube (MWCNT) in phenolic resin, which was reinforced with CG fiber. The prepared composites were tested for their adhesive wear and frictional behavior at different applied loads (up to 100 N) against EN-31 steel disk on a standard pin-on-disk tribometer. The results revealed that addition of MWCNT enhanced the pressure–velocity (PV) limit significantly and reduced the value of friction coefficient of CG-fiber-reinforced phenolic resin composite. The friction coefficient decreases with increasing applied load. The wear rate significantly depends on MWCNT contents. The contact temperature of sliding surfaces increased with increasing applied load. The worn surfaces were analyzed and discussed to understand the wear mechanism involved with the help of SEM micrographs. [ABSTRACT FROM AUTHOR]

For the molding compounds used in electronic packaging, curing accelerators play a significant effect on the curing behavior of thermosetting resins, thus the cross‐linked structure and performance of the cured product. In this study, nine commercially available imidazole compounds, divided into three types, were introduced into a polyfunctional epoxy resin (E1)/XYLOK phenolic resin (P1)/MDA benzoxazine (B1) ternary system to reduce the curing temperature for molding processing. To understand the cross‐linked structure of the cured product, the ternary system was divided into unitary system and binary system, and the curing behavior and chemical structure of each system was monitored by differential scanning calorimetry and Fourier transform‐infrared systematically. Due to the nucleophilicity of tertiary amines influenced by the steric hindrance effect, it was discovered that the reaction activity of epoxy resin initiated by nine imidazole compounds, was significantly different. However, the ring opening of benzoxazine occurs at a high temperature, even catalyzed with imidazoles, and its curing behavior was nearly the same owing to the unique ring‐opening mechanism initiated by active hydrogen of imidazole. In addition, phenolic resin elevates reaction activity for both epoxy resin and benzoxazine. The cross‐linked structure of E1P1B1 ternary system was proposed based on the experimental results from each system. It suggested that the formed network of the E1P1B1 cured product with Type I and II imidazoles is mainly IPN structure, while the cured products of E1P1B1 + Type III is the copolymerization of epoxy, phenolic and benzoxazine. This paper systematically illustrated the ideal chemical structures of epoxy resin/phenolic resin/benzoxazine ternary system with different imidazole compounds, which is valuable for industrial application of resin‐based materials. [ABSTRACT FROM AUTHOR]

In this article, nano-ZrSi2-modified phenolic (Ph) resin and nano-ZrSi2-modified quartz–phenolic (Q–Ph) composites are, respectively, prepared by resin casting and compression molding. The effect of nano-ZrSi2 on the thermal stability of Ph resin and the role of nano-ZrSi2 on the thermal reusability of Q–Ph composites are investigated by multiple thermal gravimetric analyses and mechanical tests. The strengthening mechanism of nano-ZrSi2 modification is investigated by the evolution of microstructure. The results show that the addition of nano-ZrSi2 enhances the thermal stability of Ph resin under repeated heating at 1,200°C in air. The enhancement in thermal stability of resin exhibits a positive effect on improving the thermal reusability of composites. Within the range of 20 repeated heating times, the flexural strength of nano-ZrSi2-modified composites is above 16.01 MPa, which is 163.8% higher than that of unmodified composites. The strengthening mechanism of nano-ZrSi2 is mainly in the inhibition of thermal oxidation and the reduction of microstructural defects during the repeated thermal environment. [ABSTRACT FROM AUTHOR]

This paper discusses the preparation of an asymmetric microfiltration carbon membrane made of mineral coal powder and phenolic resin. Tubular supports were obtained via extrusion of a paste prepared by mixing a carbon powder, a solution of phenolic resin and organic additives. The green tubes were cured then carbonized at 700 °C under nitrogen flow. Porous supports with an average pore diameter of 9 μm and 38% porous volume were achieved. The material presents high chemical and mechanical resistances. Experimental data showed that the particle size and homogeneity of the carbon powder are directly responsible of the average pore size and distribution of the final material. Phenolic resin acts as binder, carbon precursor and porosity agent with a constant 25% contribution to the total porous volume. The microfiltration layer was coated by means of the slip casting process, using a suspension of finely ground carbon powder dispersed in a phenolic resin alcoholic solution. Carbonization at 700 °C was necessary to obtain a defect-free layer with an average pore diameter of 0.5 and 25 μm thickness. The membrane material displayed a hydrophobic character. To increase its hydrophilic character, the membrane was oxidized under air at 350 °C for 30 min then tested for industrial wastewater filtration. The membrane's behavior complied with the Darcy's law even after oxidation. Nevertheless, the oxidation step changed the hydrophobic character of the membrane to a hydrophilic one. In fact, this treatment had a direct impact on the permeability of the membrane and on the filtration flux of industrial wastewater. The latter increased by a factor of 2.5 to 5. In addition, a total retention in turbidity was achieved with 47% of the organic matter retained by the membrane. Due to a complexation between the organic elements Ca2+ and Mg2+, the retention of these divalent ions was also important. [ABSTRACT FROM AUTHOR]

Carbon/carbon–silicon carbide (C/C-SiC) composites have been widely reported in aerospace and military projects for their mechanical properties and electromagnetic shielding characteristics. However, high production costs, a complex process, and poor electrical conductivity have prohibited the large-scale application of these excellent EMI shielding materials. Herein, in situ growth of the SiC nanofibers (SiCnf) on carbonized phenolic resin with the reinforcement of graphite fibers is proposed for a strategy to overcome this challenge. The laser-irradiated carbon fibers (LCFs) were filled into the phenolic resin and hot-pressing was conducted; thereafter, the C/C-SiC composites were obtained by high-temperature carbothermal reduction of the LCF/phenolic resin and the industrial silicon power. Because of the conductive network of the LCF, the dense carbon matrix and the decoration of nanoporous SiCnf, the as-prepared SiCnf grown on the LCF/carbonized phenolic resin (LCF/PC-SiC) composite exhibited an EMI shielding effectiveness of 27.86 dB in the X-band at room temperature. This work proposed a new strategy to efficiently fabricate C/C-SiC composites for electromagnetic shielding. [ABSTRACT FROM AUTHOR]

To solve the problem that the curing mechanism evolution of phenolic resin catalyzed by Ba(OH)2 remained unclear, the p-p methylene index, o-p methylene index, o-o methylene index, hydroxymethyl index, and ether index were introduced to quantitatively investigate the chemical structure of resin in the curing temperature range of 90–230°C. The chemical structures were investigated by variable temperature FT-IR. The gas products released with the increase of curing temperature were characterized by Thermogravimetry-Mass Spectrometry. The curing mechanism from 90°C to 230°C was concluded finally. The results show that the main reaction is the formation of the p-p methylene group in the range of 90–120°C. It is difficult to form the o-p methylene bridge at this stage. In the range of 120–160°C, the main reaction is the formation of the p-p methylene group. From 160°C to 190°C, the main reactions are the breaking of the ether bond, the formation of the carbonyl group and the propyl bridge. Above 190°C, the main reactions are polycondensation reaction among phenolic hydroxyl groups, and the formation reaction of carbonyl groups. The ether bond breaks completely above 230°C. This work provides a new method to investigate the curing mechanism. It is a benefit for the rational design of the curing process of phenolic resin-based composites. [ABSTRACT FROM AUTHOR]

Lightweight particleboards - manufacturing modification using a blowing agent from the group of bicarbonates. Although the low-density particleboards have grown in popularity, due to their facilitated transportation and a lower mass in the assembled finished products, there is still certain constraints in their use caused by limited mechanical properties. These obstacles may be overcome by the mechanism of foaming the polymers that bind wood particles in the boards' structure. The aim of this study was to determine the possibility of using sodium bicarbonate as a blowing agent of phenolic resin used for bonding wood particles in the technology of lightweight particleboards. It was found that the addition of sodium bicarbonate in the amount of 5% in relation to the dry weight of the phenolic resin significantly increase the internal bond strength of the manufactured particleboards. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangdong University of Technology is the property of Journal of Guangdong University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A thermal protection material (TPM) was prepared using Al 2 O 3 -phosphate, expanded aluminosilicate, and phenolics through compression molding and the gradient heating reaction technique, and the effect of the high-temperature treatment on the properties of the composites were investigated. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to analyze the structures and compositions of the composites. After the high-temperature treatment, the composites exhibited increased porosity, decreased density, and generated SiC particles with high strength and temperature resistance. The prepared composites have high compressive strength and compression deformation ability of the bending point. Thermogravimetric analysis, coefficient of thermal conductivity measurements, and expansion analysis were carried out to evaluate the thermal properties of the composites, and the effects of the preparation conditions on the thermal properties of the composites were investigated. The results showed that the prepared composites exhibited complete morphology, excellent high-temperature resistance, high compressive strength and toughness, and low thermal conductivity before and after the high-temperature treatment at 1000 °C, and hence showed great potential for future thermal protection applications. [ABSTRACT FROM AUTHOR]

Ablative composites have been in use for thermal protection of space vehicles for decades. Carbon-phenolic composites have proven to perform exceptionally well in these applications. However with development in aerospace industry their performance needs improvement. In this field, different carbon-based and ceramic additives have been introduced into ablative composite systems. This review article gives a comparative analysis of researches done in this field in the recent past. Density, ablative, thermal and mechanical properties of ablative composites with different ultra-high temperature ceramic particles i.e. ZrSi 2 , Cenosphere, nano-SiO 2 , BN etc. and carbon-based nanoparticles i.e. CNTs, nano-Diamonds, Graphene oxide etc. used as additives, have been compared and discussed. Emphasis is put on carbon-phenolic composite systems although some epoxy matrix systems have also been discussed for comparison. [ABSTRACT FROM AUTHOR]

In this work, phenolic resin served as binder to recycle ultrafine needle coke scrap, and then carbon/carbon composite was prepared through high-temperature graphitization. The influences of phenolic resin content on the microstructure characteristics of carbon/carbon composite were investigated by X-ray diffraction, scanning electron microscope, laser particle size, and nitrogen adsorption–desorption. When the mass ratio of ultrafine needle coke scrap to phenolic resin is 1:2, the carbon/carbon composite shows an average particle size of 19.17 μm, which is higher than that of ultrafine needle coke scrap (3 μm) and is close to that of commercial needle coke (19.12 μm). Moreover, the carbon/carbon composite as anode material for LIBs exhibits the 1st and 50th discharge capacity of 360.8 mAh/g and 352.6 mAh/g. Additionally, its coulombic efficiency after 50th cycles is over 99%. In principle, the synthesized carbon/carbon composite exhibits a comparable electrochemical performance to commercial needle coke. [ABSTRACT FROM AUTHOR]

Phenolic foams are widely used as insulation materials in construction, transportation, and spacecraft industries due to their flame retardancy, thermal stability, low toxicity, and low smoke generation. However, these foams are typically produced from non‐renewable resources. With increasing environmental pollution, volatility in petrochemical prices, and depletion of petroleum resources, the demand for polymeric materials produced from renewable resources is ever‐increasing. Numerous recent studies have introduced biomass as an alternative resource for petroleum‐based raw materials for producing phenolic foams. In addition to their environmental benefits, bio‐based phenolic foams exhibit properties similar or even superior to traditional phenolic foams. In this review, traditional phenolic foams are discussed. Recent progresses on synthesis of foams from bio‐based resources, modification of the bio‐alternatives, performance enhancements, and comparison with traditional phenolic foams are outlined. Challenges and methods to further improve performance characteristics of bio‐based phenolic foams and their expanding range of applications are highlighted. [ABSTRACT FROM AUTHOR]

A novel method was proposed to incorporate chlorophyll molecules into the phenolic resins for the photocatalytic degradation of methylene blue and synthetic blue wastewater (a mixture used as a disinfectant in airplanes, trains, and ships). A solvent-extraction method was employed for obtaining chlorophyll molecules. About 90% of the obtained chlorophyll was successfully incorporated into the phenolic resin via the Fischer esterification reaction. In addition, FTIR and UV-Vis spectrophotometry confirmed the immobilization of chlorophyll into the polymer. Although the studied photocatalysts showed the same energy gap (about 2.16 eV) and electrochemical potentials (around −0.425 V and 1.950 V), the sensitized material achieved a higher photocatalytic degradation of methylene blue in alkaline and acidic conditions. In addition, the effective photocatalytic mechanism model demonstrates the selective anion radical attack of methylene blue. Interestingly, the photocatalytic degradation of synthetic blue wastewater shows a contradictory behavior compared to the methylene blue experiments. It was enhanced at acidic conditions, reached complete decolorization, and 40% of TOC removal after 6 h of continuous irradiation. In conclusion, photocatalysis was employed to degrade synthetic blue wastewater for the first time, showing a well-functionality on a full irradiated stirred tank with the chlorophyll-sensitized phenolic resin. Highlights: Dye sensitization of phenolic resin was carried out by adding chlorophyll. Sensitized resin achieved methylene blue degradation higher than raw resin. Carbonate and superoxide radicals were the main oxidant species. Total color removal of synthetic blue wastewater was achieved after 6 h. Chlorophyll-sensitized resin removed 40% of TOC from synthetic blue water. [ABSTRACT FROM AUTHOR]

This article discusses observations on thermal stability, decomposition properties and degradation of organic components of friction composite materials fabricated by powder metallurgy techniques. N-Methylaniline modified phenolic resin used as a binder material in the preparation of composite materials. Thermogravimetry method was used to study the thermal properties of the samples. The experiments were performed on a TGA Q50 (TA Instrument) in an oxygen atmosphere. In order to better assess the thermal characteristics of the composites, the analyses were carried out by separating thermographs into three parts according to the degradation mechanism. The obtained results helped to assess the thermal stability of the friction materials. The degradation of phenolic resin was observed in the temperature range of 312–362°C. It was found that barite and copper-graphite particles improve the thermal characteristics of the samples. [ABSTRACT FROM AUTHOR]

The thermal conductivity of thermal insulation materials is generally not greater than 0.2 W/(m • K). Because of its good thermal insulation performance-it is widely used in the field of building internal and external walls, roofs and thermal insulation mortar. Fiber reinforced composite thermal insulation foams with different fiber contents (0-3wt% -6wt% and 9wt%) were prepared with phenolic resin as matrix and chopped glass fiber as modified mate rial. The mechanical properties, micro morphology and thermal conductivity of composite thermal insulation foaming materials were analyzed by electronic universal testing machine, SEM and thermal conductivity tester. The results showed that with the increased of fiber content, the compressive strength and tensile strength of fiber-reinforced composite thermal insulation foaming materials increased first and then decreased. When the content of fiber was 6wt%, the compressive strength and tensile strength of composite thermal insulation foaming material reached the maximum, which were 0.241 and ().115 MPa respectively. With the increased of fiber content, the water absorption of composite thermal insulation foaming materials decreased first and then increased, when the content of fiber was 6wt%, the water absorption reached the minimum value of 27.9%. With the increased of fiber content, the brittleness of composite thermal insulation foaming material gradually decreased and the toughness gradually increased, when the content of fiber was 9wt%, the embrittlement rate of composite thermal insulation foaming material was the lowest, which was 1().2%. When the content of fiber was 6wt%, the minimum pore size of composite thermal insulation foaming material was about 3()()/.xm. when the fiber content increased to 9wt%, the number of pores tended to increased, and the size distribution was uneven, with large pores. With the increased of fiber content, the thermal conductivity of composite thermal insulation foams decreased first and then increased. when the content of fiber was 6wt%, the thermal conductivity of composite thermal insulation foaming material reached the lowest value of ().033 W / (m • K). The overall analysis showed that when the content of fiber was 6wt%, the comprehensive performance of fiber-reinforced composite thermal insulation foaming material was the best. [ABSTRACT FROM AUTHOR]

Phenolic resin (PR) was grafted onto the surface of graphene oxide (GO) through π–π conjugation and chemical bonding. After carbonization, organic compounds turned into carbon layers with a thickness of about 10 nm and coated on the surface of GO formed a core–shell structure. Besides, the adiabatic interface formed during organic carbonization can effectively connect the aerogels into a three-dimensional network. The optimum mass ratio of GO was determined to be 10 wt% in the preparation of the precursor aerogel. The adiabatic interfaces (carbon) between GO lamellae could effectively reduce the solid phase heat transfer in aerogels (thermal conductivity is 0.0457 W m−1 K−1). At the same time, the existence of GO also ensured better mechanical properties of GO/carbon composite aerogel (compressive strength is 2.43 MPa) compared with the pure carbon aerogel (1.52 MPa), demonstrating the excellent heat-shielding performance and mechanical property of GO/carbon aerogel. [ABSTRACT FROM AUTHOR]

This study used silica sol, phenol, formaldehyde, etc. as raw materials to prepare silica sol/phenolic resin based on in-situ polymerization. The influence of silica sol content on the viscosity, solid content, and other properties of the composite resin were discussed. The structure and performance of the product were characterized and tested via laser particle size analyzer, infrared spectrum analyzer, thermogravimetric (TG) analyzer, and rheometer. The results show that the viscosity of the composite resin increased with increased silica sol content, and the solid content and the free formaldehyde content exhibited the opposite trend. The laser particle size analysis revealed that when the amount of silica sol was 40%, the particle size distribution of the composite resin was relatively uniform. Fourier transform infrared analysis illustrated a new chemical bond of Si-O-C formed between silica sol and phenolic resin. TG analysis showed that when the amount of modified silica sol was added at a 40% level, the decomposition temperature of composite resin (10% weight loss) increased from 294.8 to 324.4 °C, and the residual amount increased from 55.2% to 60.2%; rheological analysis revealed that when the content of silica sol was 40%, it had better flow properties, creating conditions for the composite resin to penetrate the wood. [ABSTRACT FROM AUTHOR]

We report a method of in-situ modification of phenolic resin (PR) on improving thermal stability with graphene/SiO2 hybrids at an ultralow filler loading. GO/SiO2 hybrids were prepared by electrostatic adsorption method and chemically reduced to RGO/SiO2 hybrids by NaBH4. The effect of in-situ modification of PR by GO/SiO2 and RGO/SiO2 on thermal stability of PR was studied. The results of SEM, XRD and FTIR showed that the hybrids and in-situ polymerization had a significant effect on improving the thermal property of PR. The TG and DTG analyses demonstrated that the thermal performance of PR in 350–500 °C was improved prominently. The T5% and T10% of 0.1 wt% (RGO–SiO2)/PR were increased by 165.56 °C and 89.23 °C compared with the pure PR, reaching 381.77 °C and 466.20 °C, respectively. Moreover, the R800°C of 0.1 wt% (GO–SiO2)/PR and 0.1 wt% (RGO–SiO2)/PR reached 69.86 wt% and 70.20 wt%, which increased by 10.75% and 11.29%, respectively, compared with pure PR. Therefore, the application of graphene/SiO2 hybrids in the in-situ polymerization modification of PR can significantly improve the thermal stability of PR and broaden its application fields. [ABSTRACT FROM AUTHOR]

The cellulose nanocrystals (CNCs) surface modified with phenolic and acrylic resins were investigated for different properties such as thermally stability and adhesive property, the mechanical properties of CNCs and interactions of the resulting materials at a micro-level are very important. Phenolic resins are of great interest due to their smooth structure, low thermal conductivity and good thermal insulation. However, the high spray rates and poor mechanical properties limit its use for external insulation of buildings. Acrylic resins are used as a matrix resin for adhesives and composites due to their adhesion, mechanical properties, and their good chemical resistance. The brittleness of acrylic resins makes them less attractive than the structural materials, being much harder. For this reason, most of the resins are modified with suitable elastomers, which act as hardeners. Therefore, treatment of these compounds is necessary. In this research paper, the effect of CNCs surface on phenolic and acrylic resins were investigated to obtain an optimized surface using three different weight (wt%) ratios of CNCs. Scanning electronic microscopy (SEM), X-rays diffraction (XRD), Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structure, and investigate different properties of CNCs. Furthermore, the Zwick/Roell Z020 model was used to investigate the adhesion properties of the phenolic and acrylic resins with CNCs. [ABSTRACT FROM AUTHOR]