Phenolic Resin Research Articles

Influence of Silicon Carbide Incorporation on Thermal and Ablation Properties of Carbon Fabric-Phenolic Resin Composites

To shield re-entry spacecraft from the extreme heat experienced during hypersonic flight through a planet's or the earth's atmosphere, thermal protection systems (TPS) were developed. This work involved the fabrication of composites using a polyacrylonitrile (PAN) based carbon fabric (Cf)-phenolic resin matrix (PR) modified with different weight percentages (wt.%) of silicon carbide (SiC), namely 0 wt.% (Cf/PR), 1wt.%, 3wt.%, and 5wt.%. The composites were prepared using the hydraulic hot press method. The manufactured composites were analyzed for their thermal conductivity and resistance to ablation using an oxyacetylene torch test. Furthermore, the ablated composites underwent X-ray diffraction (XRD), revealing a SiO2 compound layer on the ablated composite surface. The experimental results demonstrated that the Cf/PR composites modified with 3wt.% of SiC exhibited superior characteristics. The composites consist of 3wt.% Cf/PR-SiC exhibited a thermal conductivity value of 0.57 W/m K. Additionally, these composites showed a noticeable decrease in the mass ablation rate (MAR) at 0.0052 mm/sec and linear ablation rates (LAR) at 0.025061 gm/sec. This study proposed an effective way to improve the thermal and ablation characteristics of TPS materials.

Thermal stability and anti-ablation performance of plasma spray coated-YSZ on Al2TiO5 modified novel ablative carbon-phenolic composites

Abstract Despite ongoing challenges, ablative thermal protection systems are among the most promising methods for safeguarding spacecraft during re-entry thermal protection systems (TPS). A novel aluminium titanate (Al2TiO5/AT) and a highly efficient thermal barrier of coating (TB/TBCs) made from yttria-stabilized zirconia (YSZ), powder, but deposited using the plasma spray technique on polyacrylonitrile (PAN)-based carbon fiber fabric(C)-reinforced with resorcinol phenol formaldehyde resin (RF) composites (C-RF)) would be a potential candidate for TPS applications. This study investigates the composites with varying wt.% of AT that were developed, namely 0 wt.% (YSZ-C-RF), 1 wt.%, 3 wt.%, and 5 wt.% (YSZ-AT-C-RF) by utilizing a hot press moulding machine. Thermal stability and ablation performance of unmodified C-RF with modified YSZ-C-RF and YSZ-AT-C-RF composites are examined through thermogravimetric analysis (TGA) and oxyacetylene torch test/OAT (4.0 MW/m2 for 60 sec). Also, the phase composition and microstructure of the ablated surface are determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The TBC of YSZ has an obvious influence on the residual weight ratios at high temperatures in C-RF and also plays a positive role in increasing thermal stability under nitrogen atmosphere for enhancing ablation resistance concerning YSZ-C-RF. The mass and linear ablation rates (MAR and LAR) of the composites after modifying the surface by YSZ-coated particles are reduced by 82.98% and 15.65%, respectively. Similarly, the introduction of AT particles and TBC of YSZ results in evidence of improving the thermal stability and the ablation resistance in varying wt.% of YSZ-AT-C-RF composites. The primary optimum AT weight loading for enhancing ablation resistance in YSZ-C-RF composites is 1wt.%. The modification of 1wt.% AT particles and YSZ-Coated particles reduce MAR and LAR by 54.79% and 61.94%, respectively. This work offers a meaningful method to remarkably enhance the ablation performance of the modified C-RF and YSZ-AT-C-RF composites.

Effect of Resin Content on the Properties of Roofing Tile for Building Materials

The production process of roofing tile materials uses among other materials thermosetting adhesive resins normally urea formaldehyde (UF), phenol formaldehyde (PF), di-isocyanate (PMDI) at various content mixtures, 3wt%, 5wt%, 7wt%, 9w% and 11wt% with a usual thickness of 6 mm. The fibers, adhesives, and other materials are then placed into a steel mold with the standard dimensions of 400 mm x 400 mm, to be then hydraulically pressed at high pressure and the required temperature. Overall, PMDI synthetic adhesives have better physical and mechanical properties than PF synthetic adhesives, however the thermal properties of UF and PF synthetic adhesives are better than PMDI. The physical properties testing were density, humidity content, absorption of water, thickness inflated and water permeability. The mechanical properties such as modulus of rupture (MOR) and modulus of elasticity (MOE), impact strength and tensile strength are all measured according to JIS A 5908-2003, ASTM D 256-2006a,TIS 535-2556 and ASTM D1037-12.The testing for the thermal conductivity, thermal resistivity and solar reflectance were done according to ASTM C177-2010 and ASTM E 891-87. The type of resin content and adhesive used had a significant impact on the physical, mechanical and thermal properties of the roofing tile materials of showed in the results of the analysis of variance (p >0.05). The produced roofing tile has an improved thermal conductivity and heat insulation which can be a substitute for hazardous asbestos based roofing materials.

A Novel Approach to the Development of Natural Resin‐Based Biopolymer in the Presence of a Reusable Catalyst: Characterization and Modeling of Material Properties

ABSTRACTThe rise in environmental and health concerns has led to increasing attention to nature‐derived materials. Natural resin (NR) is secreted by pine trees, and it is a great monomer source for synthesizing biopolymers. The objective of this study is to produce terpene rosin phenolic resin (TRPR) from NR, turpentine, and phenol by applying a novel polymerization technique. An environmentally friendly and reusable catalyst (Amberlyst15) was chosen instead of traditional ones. TRPR samples were chemically characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC) analysis. The average molecular weight (Mw) of TRPR was detected as 560 g/mol. Artificial neural network (ANN) modeling was designed with three inputs (pressure, temperature, and terpene/NR ratio) and four outputs (reaction yield, acid value, saponification value, and softening point). The highest TRPR yield was obtained with a terpene/NR ratio of (1/2) at 80°C and under 3 atm. The lowest acid and saponification values were calculated as 90.54 and 100.11 mg KOH/g, respectively. The softening point of TRPR reached 80°C and it was suggested for use in the paper, ink, and adhesive industries.

Investigation of Mechanical Properties of Short Sisal Fiber Reinforced Phenol Formaldehyde and Vinyl Ester Composites

Composite materials are replacing standard Engineering metals and alloys for many applications. Here in this work, Sisal fiber is used as reinforcement. Since it is abundantly available in nature and majority of it is getting wasted without being used as reinforcement in engineering applications. Short Sisal fiber reinforced Phenol Formaldehyde and Vinyl Ester resin composites are prepared with varied fiber lengths (5 mm and 10 mm) and for varied weight fraction (20%, 25% and 30%) of the fibers. The short Sisal fibers are treated with 5% of Sodium Hydroxide (NaOH) solution. In the present work, the effect of the fiber treatment, fiber length and fiber loading on the mechanical properties are investigated. The results show that the Alkali Treated Sisal fiber reinforced composites have better mechanical properties than untreated composites. The 10 mm fiber length reinforced composite shown improved mechanical properties than 5 mm fiber length reinforced composite. Increase in mechanical properties is seen when the fiber content in the composite is increased from 20% to 25% and 25% to 30%. The 30% weight of the Sisal fiber reinforced composite has shown higher values of mechanical properties.

Preparation of phenol-formaldehyde composite modified with chitosan for the simultaneous removal of antibiotics and heavy metal ions in waters

In current study, a new adsorbent based on aminated phenol-formaldehyde composite was prepared using chitosan as modifier. Various techniques were adopted to characterize the morphology and structure of the prepared adsorbent. Due to the abundant amino groups, the obtained adsorbent presented satisfactory adsorption performance towards fluoroquinolones (FQs) and heavy metal ions (including Cu2+, Cd2+ and Pb2+) by means of multiple forces including electrostatic, H-bonding, π-π stacking interactions (for FQs) and chelating force (for heavy metal ions). Studies about the adsorption kinetics, isotherm and thermodynamics were performed to inspect the adsorption behaviors of studied FQs and heavy metal ions on the new adsorbent. After optimizing the adsorption parameters, the obtained adsorbent were employed to remove FQs, Cu2+, Cd2+ and Pb2+ in various environmental waters. The removal rates for FQs and heavy metal ions were 91.8–98.6 % and 94.4–98.5 %, respectively, which were significantly higher than that obtained on unmodified phenol-formaldehyde resin (20.7–49.0 % for FQs and 35.1–43.0 % for heavy metal ions). At the same time, the adsorbent exhibited good preparation repeatability in different batches, acceptable stability and reusability. The current study well demonstrated the potential application of the new adsorbent in the simultaneous removal of organic and inorganic pollutants from aqueous waters.

Simultaneous strengthening and toughening of PLA with full recyclability enabled by resin-microsphere-modified L-lactide oligomers

Various strategies have been developed to improve the brittleness of poly (lactic acid) (PLA), most of which still suffer from the toughness-strength trade-off dilemma. Herein, we prepared phenol–formaldehyde-resin microspheres (PFM) with aliphatic hydroxyl groups to initiate L-lactide polymerization and synthesized a series of PFM-modified L-lactide oligomers (PFM-OLLA) bearing different arm lengths. PFM-OLLA were then physically blended with commercial PLA in different weight ratios to prepare synchronously strengthened and toughened PFM-OLLA/PLA composites. After blending with 4 % PFM2.5-OLLA (PFM content: 2.5 %), the mechanical properties of the PFM2.5-OLLA/PLA composites were best. PFM2.5-OLLA efficiently improved the crystallization behaviors of the PFM2.5-OLLA/PLA composites, thereby significantly enhancing their strength and toughness. The maximum tensile yield strength (40.2 MPa), elongation at break (85.7 %), and impact strength (20.8 kJ/m2) of PFM2.5-OLLA/PLA composites could respectively increase by 44.2 %, 465.7 %, and 100 %, compared to the values of neat PLA. The microscopic strengthening and toughening mechanisms were attributed to the rigidity of PFM, and the heterogeneous nucleating ability as well as larger free volume of PFM2.5-OLLA, whereas the visual toughening effects were attributed to multiple crazing and shear yielding phenomena. After simple alcoholysis and filtration, the polymer components were completely converted into methyl lactate. The recycled PFM, exhibiting excellent chemical stability, were reused to synthesize a new PFM-OLLA for strengthening and toughening PLA. This study provides a sustainable strategy for the development of high-performance PLA engineering materials showing great application potentials in the automotive, electronics and housing fields.

Modification of nanolignin by deep eutectic solvent to improve the properties of phenol-formaldehyde resin

Modification of nanolignin by deep eutectic solvent to improve the properties of phenol-formaldehyde resin

Solid-State Structures and Properties of Lignin Hydrogenolysis Oil Compounds: Shedding a Unique Light on Lignin Valorization

This article explores the important, and yet often overlooked, solid-state structures of selected bioaromatic compounds commonly found in lignin hydrogenolysis oil, a renewable bio-oil that holds great promise to substitute fossil-based aromatic molecules in a wide range of chemical and material industrial applications. At first, single-crystal X-ray diffraction (SCXRD) was applied to the lignin model compounds, dihydroconiferyl alcohol, propyl guaiacol, and eugenol dimers, in order to elucidate the fundamental molecular interactions present in such small lignin-derived polyols. Then, considering the potential use of these lignin-derived molecules as building blocks for polymer applications, structural analysis was also performed for two chemically modified model compounds, i.e., the methylene-bridging propyl-guaiacol dimer and propyl guaiacol and eugenol glycidyl ethers, which can be used as precursors in phenolic and epoxy resins, respectively, thus providing additional information on how the molecular packing is altered following chemical modifications. In addition to the expected H-bonding interactions, other interactions such as π–π stacking and C–H∙∙∙π were observed. This resulted in unexpected trends in the tendencies towards the crystallization of lignin compounds. This was further explored with the aid of DSC analysis and CLP intermolecular energy calculations, where the relationship between the major interactions observed in all the SCXRD solid-state structures and their physico-chemical properties were evaluated alongside other non-crystallizable lignin model compounds. Beyond lignin model compounds, our findings could also provide important insights into the solid-state structure and the molecular organization of more complex lignin fragments, paving the way to the more efficient design of lignin-based materials with improved properties for industrial applications or improving downstream processing of lignin oils in biorefining processes, such as in enhancing the separation and isolation of specific bioaromatic compounds).

Exploring alternatives for detecting microplastics in the human body: questionnaire survey

Microplastics (MPs) can enter the body via plastic products. Given modern plastic exposure, we seek to assess MP exposure in large populations through epidemiological tools. In this quasi-experimental study, every participant filled out a questionnaire, and those who satisfied any of the following requirements were not allowed to continue in the study: Diabetes, ulcerative colitis, Crohn’s disease, infectious diseases. Participants in the exposure and control groups were provided three hot meals in disposable plastic tableware (DPT) (n = 30) or non-DPT (n = 30), respectively. After a month of observation, individuals in the exposure group discontinued the three meals provided in DPT (n = 27) for 1 month as the post-exposure group. Each Participant in the three groups received a questionnaire survey and fecal sample collection. We compared the differences in MP levels between different groups and used the Bland–Altman analysis method to evaluate the consistency of the results obtained by different measurement methods. Statistically significant differences in the total quantity (P (0.80 matching degree) = 0.020; P (0.65 matching degree) < 0.001) and types (Polyethylene Terephthalate (EVA) (P = 0.039), Polyethylene Terephthalate (PET) (P = 0.022), Polyvinyl Butyral (PVB) (P = 0.013), Chlorinated Polyethylene (CPE) (P = 0.039), phenolic epoxy resin (P = 0.012)) of MPs were observed between the exposure and post-exposure groups. The Bland–Altman analysis results indicate that the two methods exhibit good consistency in the three groups (control group: mean difference = 0.54, agreement limits (95% CI) = − 0.44 ~ 1.54; exposure group: mean difference = 0.41, agreement limits (95% CI) = − 0.19 ~ 1.01; post-exposure group: mean difference = 0.19, agreement limits (95% CI) = − 0.63 ~ 1.02). The method based on questionnaire surveys can substitute the method of fecal sample detection to evaluate the exposure of MP particles.

Direct ink writing of engineered MOF-based hybrid composite empowering dendrite free zinc ion battery anode

The relationship between morphology and electrochemical performance of zinc-ion battery (ZIB) anodes is crucial. Optimizing zinc-ion intercalation efficiency, suppressing dendrite formation, and mitigating shape changes are achievable through thoughtful anode architecture design. Herein, we have engineered a hybrid composite by coordinating a metal-organic framework with phenolic formaldehyde resin using a direct ink writing approach to rationally design a gridline-patterned 3DP-UiON-PHC@Zn. This anode in a symmetrical cell shows exceptional stability with a low voltage hysteresis of 15 mV at 0.1 mA cm−2 over 2375 h and 67 mV at 0.5 mA cm−2 over 4470 h. When paired with a 3DP-VOC@Al cathode in a full cell, it achieves a remarkable areal capacity of 85.1 mAh cm2 (94.8 %) and maintains a capacity retention of 122 mAh g−1 (88.6 %) over 900 cycles at 0.1 A g−1. It also offers a power density of 69.1 W kg−1 and an energy density of 34.6 Wh kg−1. Kinetic analysis reveals that the charge storage mechanism is primarily capacitive (94.7 %). This study concludes that DIW significantly improves anode performance by minimizing dendrite growth and improving electrochemical stability, while the 3D-printed hybrid composite ensures robust mechanical stability and a porous structure.

Effect of Phenolic Resin on the Friction Performance of Composites with Hemp Fiber for Automotive Brake Pads

Effect of Phenolic Resin on the Friction Performance of Composites with Hemp Fiber for Automotive Brake Pads

Supercapacitor electrodes derived from ultra-high surface area activated carbon spheres synthesized by fluidized activation

This study thoroughly investigated the effects of activation conditions on pore structure development using response surface methodology with a central composite design. The activated carbon sphere (ACS) derived from phenolic formaldehyde resins by carbonization and fluidized activation was examined and characterized. The pore size distribution of ACS samples was all in the microporous and mesoporous scales. ACS with an ultra-high specific surface area of 3142 m2 g−1 and total pore volume of 1.513 cm3 g−1 was successfully obtained at 900 °C for 4 h. Electric double-layer capacitor (EDLC) electrodes derived from ACS with different activation conditions were examined by using cyclic voltammetry and galvanostatic charge/discharge to comprehend the influence of surface area, pore volumes, and the amount of binder on the electrochemical performance. The optimal EDLC electrode was obtained using ACS with the largest specific surface area and pore volume with 5 wt% of binder addition. The specific capacitance was 143.7 F g−1 in a 1 M H2SO4 solution. The cyclical stability of the carbon electrode was also examined under 5000 cycles, and the charge/discharge efficiency remained nearly 100 % without deterioration. This study provides insights into fabricating ultra-high surface area ACS and their potential application as supercapacitors.

Graphene oxide/polydopamine interface co-reinforced carbon paper: With comprehensive mechanical properties, electrical conductivity and air permeability

Proton Exchange Membrane Fuel Cell ( PEMFC) are characterised by their cleanliness, efficiency and lack of pollution. Carbon paper, the fundamental material for constructing gas-diffusion layer (GDL), plays a crucial role in electron transmission, supporting the electrode structure, and proton transport. However, the traditional carbon paper for GDL significantly limits the large-scale commercial application of PEMFC due to its low mechanical strength and poor conductivity. Based on this, in this paper, polydopamine is used to modify primary carbon fiber paper, a homogeneous mixed solution of graphene oxide and phenolic resin is used as the impregnating agent, and the effects of different GO concentrations on the properties of carbon paper are investigated. The results show that the graphitization degree and mechanical properties of carbon paper are improved with the increase of GO concentration. When the content of polydopamine is 2 g/L and the concentration of GO is 0.5 wt%, the carbon paper exhibits optimal performance. The air permeability of carbon paper is 12.18 L/min, the resistivity is 13.5 mΩ·cm, and the tensile strength is 19.3 MPa. This study provides a simple method for preparing highly breathable and highly conductive carbon paper, offering a reference for achieving low-cost and high-performance carbon paper production, and facilitating the large-scale commercial production of carbon paper.

Preparation of highly graphitized porous carbon and its ethane/ethylene separation performance

The efficient separation of ethane (C2H6) and ethylene (C2H4) is crucial for the preparation of polymer-grade C2H4, necessitating the development of highly selective and stable C2H6/C2H4 adsorbents. Highly graphitized porous carbon, denoted GC-800, was synthesized by polymerization at room temperature followed by carbonization at 800 °C using phenolic resin as the precursor and FeCl3 as the iron source. Vienna Ab-initio Simulation Package (VASP) calculations confirmed a higher binding energy between C2H6 molecules and graphitized porous carbon surfaces, so that a high degree of graphitization increased the adsorption capacity of porous carbon for C2H6. However, catalytic graphitization using Fe at high temperatures disrupted the microporous structure of the carbon, thereby reducing its ability to separate C2H6/C2H4. By controlling the carbonization temperature, the degree of graphitization and pore structure of the porous carbon could be changed. Raman spectra and XPS spectra showed that the GC-800 had a high degree of graphitization, with a sp2 C content as high as 73%. Low-temperature N2 physical adsorption measurements estimated the specific surface area of GC-800 to be as high as 574 m2·g−1. At 298 K and 1 bar, it had an equilibrium adsorption capacity of 2.16 mmol·g−1 for C2H6, with the C2H6/C2H4 (1:1 and 1:9, v/v) ideal adsorbed solution theory selectivity respectively reaching 2.4 and 3.8, significantly higher than the values of most reported high-performance C2H6 selective adsorbents. Dynamic breakthrough experiments showed that GC-800 could produce high-purity C2H4 in a single step from a mixture of C2H6 and C2H4. Dynamic cycling tests confirmed its good cyclic stability, and that it could efficiently separate C2H6/C2H4 even under humid conditions.

Effects of carbon on the synthesis and densification of tantalum carbide powder

Tantalum carbide (TaC) powder was synthesised at 1500 ºC by sol-gel and carbothermal reduction processes using tantalum pentachloride (TaCl5) and phenolic resin as the starting materials. The effects of the C/Ta ratios in the Ta-containing precursor on the reaction yield, microstructure, chemical composition, and sinterability of the powders were investigated. The results showed that a high C/Ta ratio was favourable for the formation of TaC powder. With an increase in the C/Ta ratio, the oxygen content of the powder decreased, whereas the free carbon content increased. Consolidated TaC ceramics with high relative density (> 97%) were obtained at 1900 ºC for 5min under 80MPa after sintering the powder synthesised at C/Ta ratios of 4.00 and above. However, the hardness and fracture toughness of the TaC ceramics were slightly reduced when the C/Ta ratio exceeded 4.00, owing to weak interface bonding caused by excessive free carbon in the powder. It was found that sintering TaC powders prepared at a C/Ta ratio of 4.00 produced dense TaC ceramics, with a Vickers hardness and fracture toughness of 16.54GPa and 3.72GPa∙m1/2, respectively.

Aramid Nanofiber-modified Carbon Paper to Enhance Adaptability and Performance of Proton Exchange Membrane Fuel Cells

This study developed a novel method to enhance the comprehensive performance of carbon paper (CP) by using aramid nanofibers (ANF) modified phenol formaldehyde resin (PF). The effect of ANF modification ratios (0wt%, 0.6wt%, 1.2wt%, 1.8wt%, 2.4wt%) on ANF dispersion in PF impregnation solution, PF thermal stability, and PF carbon matrix structure were investigated. Compared to unmodified PF, ANF-modified PF matrix carbon exhibited increasingly regular and ordered structures, with the ID/IG value decreasing from 2.16 to 2.02. Furthermore, with ANF modification ratio increasing, the tensile strength, flexural strength, porosity and gas permeability of CP exhibited a pattern of initial increase followed by a decrease, and when increasing to 1.8%, reaching the optimal values of 14.28MPa, 531.61MPa, 85.94%, and 2520L·m-2·s-1, respectively. The limiting power density of proton exchange membrane fuel cells (PEMFCs) assembled with 1.8wt% ANF-modified CP gradually increased with different assembly torques of 2, 4 and 6N·m, reaching maximum values of 0.86, 0.98, and 1.1W·cm-2, respectively. Therefore, the novel ANF modification method of CP provides new insights into enhancing PEMFCs assembly adaptability, potentially addressing issues related to low mechanical stability and poor pore structure affecting PEMFCs performance.

High-temperature tribological evaluation of cobalt-based laser cladded disc for automotive brake systems

This study investigates the high-temperature wear behavior of laser-cladded (LC) cobalt-based Stellite 6 alloy coatings and compares the wear resistance of the cladding layer to the grey cast iron (GCI) substrate material at three different elevated temperatures: 150 °C, 250 °C, and 350 °C. Wear mechanisms at elevated temperatures were analyzed using SEM-EDS and Raman Spectroscopy to understand the material removal processes and degradation for the discs and counterpart composite friction material pins, respectively.The results indicated a significant improvement in wear resistance for cobalt-based alloy cladding at high temperatures. Wear rates were reduced by 5.0 %, 43.0 %, and 16.0 % at 150 °C, 250 °C, and 350 °C, respectively. The LC - brake pin tribo-pair exhibited a continuous increase in friction coefficients (CoF) with an increase in testing temperatures. The wear mechanism for laser-cladded discs exhibited a combination of abrasive and adhesive wear, with abrasive wear prevailing at 150 °C and increased adhesive wear at 250 °C and 350 °C. However, at 350 °C, decomposition of phenolic resin and the adhesive wear mechanism, led to brake pin failure. For GCI discs oxidative wear was identified as the predominant wear mechanism. The improved knowledge of wear mechanisms on LC Stellite 6 against composite brake pins, is set to enhance surface modification of GCI for brake disc applications.

Behaviors and Mechanism of Volatiles Producing during Coal Pyrolysis with Calcium Oxide Loading: Insights from Model Compounds Analysis

Calcium is a highly effective catalyst for controlling the tar compounds produced during the pyrolysis of low-rank coal, forming valuable end products. However, the exact catalytic mechanism of calcium in coal pyrolysis remains unclear due to the complex nature of coal. In this study, the pyrolysis process and tar composition of lignite, both with and without the addition of calcium, were investigated across three distinct temperature intervals. The addition of calcium oxide increased the hydrocarbon content of tar by 16.39% in the low-temperature range and 26.53% in the intermediate-temperature range. Four model compounds containing different coal-related functional groups were selected to investigate the effects of calcium on pyrolysis performance and tar composition using thermogravimetric analysis, fixed bed reactor experiments, gas chromatography/mass spectrometry, in situ Fourier transform infrared spectroscopy, X-ray diffractometer, and X-ray photoelectron spectroscopy. The addition of calcium did not affect the thermal decomposition of polystyrene or polyethylene terephthalate; however, the primary pyrolysates underwent secondary reactions on the surface of calcium, which affected the composition of the liquid pyrolysis product. Meanwhile, calcium interacted with the carboxyl and phenolic hydroxyl groups in trimeric acid and phenolic resin to form carboxylates and phenates, which affected the thermal reaction and distribution of liquid products. The influence of calcium on the transformation mechanism of coal-related functional groups provides a theoretical basis for understanding the mechanism of calcium-catalyzed coal pyrolysis.

Ablation resistance and high-temperature insulation capacity of TiB2-B4C modified Al-coated carbon fibre/boron phenolic resin ceramizable composites

The inherent susceptibility to oxidation limits the application of carbon fibre/phenolic resin composites (CF/Ph) in the thermal protection of hypersonic vehicle engines. Herein, TiB2-B4C modified Al-coated carbon fibre/boron phenolic resin ceramizable composites were fabricated. The optimal ceramizable composite (T30C10) exhibited excellent ablation resistance and high-temperature insulation capacity at a linear ablation rate and bottom-surface temperature of -0.00768 mm/s and 129.8 °C, respectively. Oxygen consumption and inhibition, carbon fixation, and self-healing effects contributed to the excellent ablation resistance, and the effects of the Al coatings and carbothermal reduction reactions led to excellent high-temperature insulation capacities.