Conventional Phenolic Resins Research Articles

Improving Pore Characteristics, Mechanical Properties and Thermal Performances of Near-Net Shape Manufacturing Phenolic Resin Aerogels.

Thermally stable high-performance phenolic resin aerogels (PRAs) are of great interest for thermal insulation because of their light weight, fire retardancy and low thermal conductivity. However, the drawbacks of PRA synthesis, such as long processing time, inherent brittleness and significant shrinkage during drying, greatly restrict their wide applications. In this work, PRAs were synthesized at ambient pressure through a near-net shape manufacturing technique, where boron-containing thermosetting phenolic resin (BPR) was introduced into the conventional linear phenolic resin (LPR) to improve the pore characteristics, mechanical properties and thermal performances. Compared with the traditional LPR-synthesized aerogel, the processing time and the linear shrinkage rate during the drying of the PRAs could be significantly reduced, which was attributed to the enhanced rigidity and the unique bimodal pore size distribution. Furthermore, no catastrophic failure and almost no mechanical degradation were observed on the PRAs, even with a compressive strain of up to 60% at temperatures ranging from 25 to 200 °C, indicating low brittleness and excellent thermo-mechanical stability. The PRAs also showed outstanding fire retardancy. On the other hand, the PRAs with a density of 0.194 g/cm3 possessed a high Young's modulus of 12.85 MPa and a low thermal conductivity of 0.038 W/(m·K).

Porous phenolic resin regulated by alcohol-based deep eutectic solvent for selective extraction and separation of tanshinones from Salvia miltiorrhiza

Deep eutectic solvents (DES), regarded as promising green solvents, have gained attention due to their distinctive properties, particularly in analytical chemistry. While the use of DES in solvent extraction and separation has been extensively studied, its application in the synthesis of adsorbents has just begun. Phenolic resin, with its polyhydroxy structure and stable spherical morphology, could serve as an effective as adsorbents for enrichment of active ingredients in herbal medicine. Designing adsorbents with high selectivity and adsorption capacity presents a critical challenge in the enrichment of active ingredients in herbal medicine. In this study, alcohol-based DESs were employed as regulators of morphology and structure instead of organic solvents, facilitating the creation of polyhydroxy structure, adjustable pores and high specific surface areas. The resulting DES-regulated porous phenolic resin demonstrated enhanced extraction and separation capacity for active ingredients compared to conventional spherical phenolic resin owing to the alcohol-based DES offering more interaction modes with the analytes.

Exploring the potential of benzoxazine-based nanocomposites for lightweight neutron shielding applications

Given their substantial neutron capture cross-section, extreme hardness, and high chemical and thermal stability, boron-based materials are widely used as building blocks to protect against highly ionizing radiations such as gamma rays and neutrons. Indeed, uncontrolled nuclear radiation exposure can be highly hazardous to radiation workers and the general public. In this sense, this work presents an extensive study and experimental evaluation of the nuclear shielding features of boron carbide (B4C) based nanocomposite, where bisphenol-A based polybenzoxazine (BA-PBz) was used as matrix. The latter was used for its wide range of interesting properties that overcome some of the shortcomings of conventional phenolic resins. A two-pot synthesis process was adopted for the synthesis of (BA-Bz) monomer. Moreover, the boron carbide nanoparticles were treated with a silane (KH-560) coupling agent in order to improve the intramolecular interactions with the polymeric matrix. The neutron shielding studies were carried out at the Nuclear Research reactor of Algeria NUR. The results showed that the developed boron carbide-based nanocomposite exhibits intriguing shielding performances and good thermal stability. The highest performances were obtained at a B4C concentration of 5. wt %, where the macroscopic cross section was found to be (Σ = 3.3878 cm−1) with a screening ratio of (S = 97.78%).

Ferrocenecarboxaldehyde modified terephthalaldehyde-phenolic resin: A comprehensive study on the synthesis, curing behavior, and pyrolysis process

To meet the demand for high performance carbon-based materials, catalytic graphitization particles are widely used to improve the thermal stability and char yields of conventional phenolic resins. The direct addition of inorganic particles may cause significant phase separation and reduce the crosslinking density of phenolic resins. In the study, a non-hazardous aromatic dialdehyde, terephthalaldehyde (TPA), was utilized to synthesize a formaldehyde-free phenolic resin (PTPA). A high char yield ferrocenecarboxaldehyde modified terephthalaldehyde-phenolic resin (Fc-PTPA) with a value of 76.0% at 800 °C was obtained by co-curing ferrocenecarboxaldehyde (Fc) and PTPA. The curing process of Fc-PTPA and the carbide structural evolution during pyrolysis were studied. The results show that Fc could act in the second stage of curing which led to an increase in the crosslinking density of resin. The generated Fe3C during the pyrolysis of Fc-PTPA contributed to form a more ordered carbide structure which was an important reason for the improvement in the thermal properties and char yields.

Study on the Preparation and Performance of Silicone-Modified Phenolic Resin Binder for Rail Grinding Wheels.

A scheme for manufacturing heavy-duty rail grinding wheels with silicone-modified phenolic resin (SMPR) as a binder in the field of rail grinding is presented to improve the performance of grinding wheels. To optimize the heat resistance and mechanical performance of rail grinding wheels, an SMPR for industrial production of rail grinding wheels was prepared in a two-step reaction using methyl-trimethoxy-silane (MTMS) as the organosilicon modifier by guiding the occurrence of the transesterification and addition polymerization reactions. The effect of MTMS concentration on the performance of silicone-modified phenolic resin for application in rail grinding wheels was investigated. The molecular structure, thermal stability, bending strength, and impact strength values of the SMPR were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and mechanical property testing, and the effect of MTMS content on the resin properties was investigated. The results indicated that MTMS successfully improved the performance of the phenolic resin. The thermogravimetric weight loss temperature of the SMPR modified by MTMS with 40% phenol mass at 30% weight loss is 66% higher than that of common phenolic resin (UMPR), exhibiting the best thermal stability; in addition, its bending strength and impact strength were enhanced by approximately 14% and 6%, respectively, compared with those of common UMPR. This study utilized an innovative Bronsted acid as a catalyst and simplified several intermediate reactions in the conventional silicone-modified phenolic resin technology. This new investigation of the synthesis process decreases the manufacturing cost of the SMPR, liberates it from the restrictions of grinding applications, and enables the SMPR to maximize its performance in the rail grinding industry. This study serves as a reference for future work on resin binders for grinding wheels and the development of rail grinding wheel manufacturing technology.

Healable ablative composites from synergistically crosslinked phenolic resin

Due to the excellent processability and high char yield, phenolic resin plays a pivotal role in ablative thermal protection systems for the aerospace industry. However, internal defects in conventional phenolic resin matrix composites could potentially scrap the entire thermal protection system and cause devastating safety hazards to the spacecraft. Herein, hexamethylenetetramine (HMTA) and phenylboronic acid are applied as the co-curing agents of novolac resin. With the HMTA amount below 2.5 phr, a series of synergistically crosslinked phenolic resin (HPNR), which consist of both traditional methylene linkages and dynamic boronic ester linkages, are successfully synthesized. By tuning the ratio of the traditional/dynamic bonds, the HPNR demonstrates high char yield and controlled plasticity. Compared with its conventional counterparts, the carbon fabric reinforced HPNR matrix composites show healing capability and superior mechanical properties and ablation resistance, with an interlayer shear strength and mass ablation rate of 37.0 MPa and 0.055 g/s, respectively. The synergistic crosslinking strategy provides a promising pathway for designing and preparing healable ablative thermal protection system materials.

Eucalyptus Bark as Source of Bio-oil or Phenolic Compounds

Background: Eucalyptus bark and scraps are generated in the production of mediumdensity fiberboard (MDF). An approach aiming to add value to such wastes was studied, following the concepts of circular economy and biomass cascade strategy. Bio-oil and phenolic resin were produced by pyrolysis from two types of biomass, Eucalyptus bark and MDF waste. As is well known, conventional phenolic resins are normally obtained from fossil resources. These products were obtained from the pyrolysis of two types of biomass to reduce environmental waste and dependence on petroleum-based products. Objective: The main objective of the present study was to produce phenolic resin from Eucalyptus wastes, aiming to reduce the fossil dependence on conventional resins used in the production line of MDF. Methods: Fast pyrolysis and slow pyrolysis were employed for bio-oil and phenolic resin production. The bio-oil and resins were characterized with standard lab analyses for their physicochemical properties, while their thermal properties were studied via thermogravimetric analysis (TGA). Results: The shear strength of the lap internal bonding of the phenolic resin binders with 19.8% of bio-oil was 2.09, 1.34, and 1.63 MPa under dry, boiler, and soaked conditions, respectively, which was acceptable for panel fabrication and can represent a significant saving in terms of fossil resins and cost reduction. Discussion: According to the results, 1 g medium fraction of bio-oils was equivalent to 1.35 g of conventional phenols, indicating those bio-oils as phenolic structures that could be used as binders. The bio-oil yields for bark and MDF were 40.9 and 25.1, respectively, which indicate a potential for replacing the conventional fossil-based phenolic resin. Conclusion: The results revealed the possibility of replacing conventional fossil-based chemicals with phenolic resin from renewable resources with similar overall properties, replacing about 1/3 of the conventional resin.

High-performance hard carbon anode prepared via an ingenious green-hydrothermal route

Phenolic resin, as a synthetic polymer precursor of hard carbon, has become the core anode precursor of sodium-ion batteries (SIBs). However, the carcinogenic formaldehyde is normally adopted in the synthesis of conventional phenolic resins. Meanwhile, the synthetic process is multifarious and prolonged, which is detrimental to mass production. In this paper, an eco-friendly phenolic resin was prepared by an efficient hydrothermal synthesis process using gentle and slightly toxic glyoxylic acid instead of notorious carcinogen formaldehyde. By adjusting the carbonization temperature of as-obtained phenolic precursor, the acquired optimal hard carbon anode material equipped a splendid reversible capacity of 325 mAh g−1 and a high initial coulombic efficiency (ICE) of 88.59%. Besides, it displayed an outstanding rate performance of 161.4 mAh g−1 for 300 cycles at 5 C with the capacity retention rate of 93.31%. When matched against the appropriate cathode, the full battery can provide a high energy density of 239 Wh kg−1, displaying excellent rate capability and cycling stability. The participation of “green” aldehyde monomer in hydrothermal synthesis process for acquiring phenolic resin is an efficient and scalable approach for obtaining higher energy storage anode, which can pave environmentally-friendly way for the realization of large-scale energy storage application.

Synthesis of Novel Benzoxazines Containing Sulfur and Their Application in Rubber Compounds.

This work reports the synthesis and successful use of novel benzoxazines as reinforcing resins in polyisoprene rubber compounds. For this purpose, three new dibenzoxazines containing one (4DTP-fa) or two heteroatoms of sulfur (3DPDS-fa and 4DPDS-fa) were synthesized following a Mannich condensation reaction. The structural features of each benzoxazine precursor were characterized by 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and Raman. The new precursors showed well suited reactivity as characterized by differential scanning calorimetry (DSC) and rheology and were incorporated in rubber compounds. After the mixing, the curing profiles, morphologies and mechanical properties of the materials were tested. These results show that the structural feature of each isomer was significantly affecting its behavior during the curing of the rubber compounds. Among the tested benzoxazines, 3DPDS-fa exhibited the best ability to reinforce the rubber compound even compared to common phenolic resin. These results prove the feasibility to reinforce rubber compounds with benzoxazine resins as a possible alternative to replace conventional phenolic resins. This paper provides the first guide to use benzoxazines as reinforcing resins for rubber applications, based on their curing kinetics.

Bio-Crude by Acidic Phenolation and Carbamation for the Preparation of Phenolic Thermosetting Resin and Its Application in Thermoresistant Laminates

Abstract Fir sawdust was liquefied in phenol solvent under acidic catalyst at 135, 150 and 165 °C, respectively; after neutralization, bio-crude was obtained where contained oil-like liquid and tiny powder-like residue. The bio-crude was chemically modified with urea at high temperature (e. g. > 130 °C) to form carbamate so as to improve chemical reactivity of bio-crude in phenolic resin synthesis. The carbamate-containing bio-crude was condensed with paraformaldehyde into thermosetting phenolic resin. Finally, this biomass-derived phenolic resin matrixed silica fabric laminates were processed. The uncured and thermally cured bio-based resins were characterized by the techniques of Differential Scanning Calorimetry (DSC), Fourier Transform Infrared spectrum (FT-IR), rheology and Thermogravimetric Analysis (TGA), and the laminates’ structure and mechanical performances were studied using the methods of Scanning Electron Microscopy (SEM), three point bending mechanical test and Dynamic Mechanical Analysis (DMA). The results showed: (1) the chemical reactivity of bio-crude was highly improved by carbamation; (2) biomass-derived thermosetting phenolic resin was thermally curable at 150–250 °C (with two exothermic peaks at 185 °C and 220 °C); (3) the char yield was about 47 %, which was not in apparent relationship with sawdust liquefaction temperatures; (4) flexural strength of silica fabric laminates at room temperature was around 357 MPa (similar with that of conventional phenolic laminate); (5) glass transition temperature of silica fabric laminate was above 270 °C (much higher than Tg of conventional phenolic resin laminate, which is normally at 215 °C). The biomass-derived phenolic resin is expected to be widely used as cost-effective and environment-friendly thermosetting resin in the application of high-performance composites.

Preparation and properties of phosphorus‐ and silicon‐modified phenolic resin with high ablation resistance

ABSTRACTIn order to further improve the ablation resistance of common phenolic resins, a modified phenolic resin containing phosphorus and silicon (SPPR) was synthesized and the corresponding properties were evaluated. With phosphorus and silicon involved in the macromolecule, SPPR showed excellent flame retardancy and obviously enhanced value (44.8%) of the limiting oxygen index. The thermal stability and charring performance of SPPR were greatly improved, with maximum decomposition temperature of over 500 °C and carbon yield of 60.1% in nitrogen. Differential scanning calorimetry indicated that the curing temperature shifted from 157 °C for the conventional phenolic resin to 182 °C for SPPR. Moreover, an improvement of impact strength from 4.3 to 16.5 kJ m−2 confirmed that incorporation of flexible SiO chain had a noticeable effect on the mechanical properties of SPPR. Such a modified phenolic resin has promising application prospects serving as an ablation material with high performance. © 2019 Society of Chemical Industry

Preparation and properties of a novel addition‐curable phenolic resin containing boron element

A novel addition‐curable novolac resin containing boron element (BPN) was successfully synthesized by a two‐step procedure, including addition‐condensation reaction between 4‐hydroxyphenylboronic acid and formaldehyde to obtain boron hybrid novolac resin (BN resin), and Williamson etherification reaction between the as‐obtained BN resin and propargyl bromide. Molecular structure of the BPN resin was characterized with Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and gel permeation chromatography. Cure behavior of BPN resin was investigated by differential scanning calorimetry. Thermogravimetric analysis (TGA) was used to evaluate thermal and thermo‐oxidative stability of cured BPN resin. The results of TGA showed that the residual weight in nitrogen of cured BPN resin was 75.16% at 800°C, which was about 15% higher than that of conventional phenolic resin. Moreover, the residual weight in air of cured BPN resin was about 30% at 750°C; in contrast, conventional phenolic resin completely decomposed under the same condition, revealing that the cured BPN possessed excellent thermal and thermo‐oxidative stability.

Preparation of phosphorus‐containing phenolic resin and its application in epoxy resin as a curing agent and flame retardant

For the sake of improving the flame retardancy of epoxy resin (EP), a novel phosphorus‐containing phenolic resin (PPR) synthesized in our group instead of conventional phenolic resin (PR) was used to cure EP in the present research. The curing processes and the corresponding crosslinking structure and mechanical performance were investigated by differential scanning calorimeter and dynamic mechanical thermal analysis. Because of the introduction of flame‐retarding elements including P and Si, PPR exhibited higher charring capacity in the condensed phase, which is helpful to construct a char layer of higher quality. Correspondingly, PPR‐cured EP displayed remarkably improved flame retardance as compared to conventional PR‐cured EP through the related evaluations including limiting oxygen index, vertical burning test, and microscale combustion colorimeter. As a multifunction agent, it is believable that PPR possesses potential commercial value to prepare flame‐retardant EP with high performance.

Degradation behavior of carbon nanotubes/phenol-furfuryl alcohol multifunctional composites with aerospace application

Lightweight and highly conductive composite associated with good impact and tribological properties could be used in the aerospace industry to replace metal for an aircraft skin and still provide effective shielding against electromagnetic interference (EMI). Also, phenol-furfuryl alcohol resins (PFA) are excellent candidates to replace existing thermoset matrices used for obtaining glassy carbon, both in its pure form and reinforced with nanoscale structures. The synthesis of PFA allow obtaining a resin with better properties than that showed by conventional phenolic resins and with synthesis and cure processes more controlled than observed for the furfuryl alcohol resin. This work has as main purpose the synthesis and thermal characterization of PFA resin and its nanostructured composites with different concentrations of carbon nanotubes (0, 0.1, 0.5 and 1.0 wt%). PFA resin was synthesized with 1:2:1 molar ratio of phenol/formaldehyde/furfuryl alcohol, according to the more appropriate condition obtained previously. The specimens were evaluated by thermogravimetry (TGA) to knowledge of the temperature of thermal degradation, either by actual analyses as simulated by simulation heating rate conversion software (known as Highway Simulation). The introduction of CNT in PFA sample does not affect its thermal stability. The values of residual weight found for samples with CNT additions are close to the values of the phenolic resin in the literature (about 60% residual weight).

Dry sliding friction and wear behavior of bronze matrix composites reinforced with Ni3Al particles: Comparison with conventional brake lining

Abstract Bronze matrix composites reinforced with Ni3Al particles were produced by means of a classical powder metallurgy (PM) technique. The Ni3Al particles used as reinforcement were produced by ball milling of cast alloy. The powders of the constituents of the bronze and Ni3Al powder were blended, compressed axially and sintered. The microstructures of the composites were characterized using optical microscopy and scanning electron microscopy. The compression strength and hardness of the composites were investigated. The tribological properties of composites and unreinforced bronze were determined using pin-on-disk geometry and results were compared with conventional phenolic resin bonded brake lining. The results showed that the PM bronze had higher strength than the composites while the hardness of the composites was higher than the PM bronze. According to dry sliding friction and wear tests, the composites have higher wear resistance and coefficient of friction than the conventional brake lining.

Propargyl resin derived from biosynthesized oligophenols for the application of high temperature composite matrix

AbstractA novel addition‐cure‐type propargyloligophenol resin for high‐temperature usage was prepared via a two‐step process: Horseradish Peroxidase (HRP) catalyzed oxidation polymerization of phenols to oligophenols, and Williamson etherification of oligophenols to propargyloligophenols. Propargyloligophenols possess an ideal processability for composite manufacture, i.e. good solubility, low melting point (< 50 °C), and thermal curability. As shown by Differential Scanning Calorimetry (DSC), propargyloligophenol resin upon heating experiences a broad thermal exothermic peak in the range of 175–300 °C peaking at around 260 °C. The cured resin is high‐temperature resistant with an initial decomposition temperature > 400 °C and an anaerobic char yield > 60 % at 700 °C. The mechanical properties of glass fabric‐reinforced propargyloligophenol laminate were superior to those of conventional phenolic resins. The results showed that propargyloligophenol resin is a prospective polymeric matrix for high temperature composites.

A new strategy for preparing oligomeric ionic liquid gel polymer electrolytes for high-performance and nonflammable lithium ion batteries

In the present work, a new strategy is used to economically synthesize an oligomeric ionic liquid from conventional phenolic epoxy resin. This oligomeric ionic liquid is further blended with PVdF-co-HFP and organic liquid electrolyte to prepare a high performance, nonflammable gel polymer membrane. Although the liquid electrolyte uptake is low (< 50%) for this novel gel polymer electrolyte, it possesses high ionic conductivities of 2.0mScm−1 at 30°C and 6.6mScm−1 at 80°C, respectively. The AC impedance results show that the interfacial compatibility between this gel polymer electrolyte and the electrodes is good. These two factors result in high cell capacity under different charge/discharge rates. Further, excellent cell-cycle stability after being charged and discharged 100 cycles is also demonstrated with the columbic efficiency to be up to 99. Due to the existence of the oligomeric ionic liquid, this novel gel polymer electrolyte exhibits superior dimensional stability; that is, at high temperature (150°C) the dimensional change is less than 1%. Notably, the electrolyte’s limiting oxygen index can be as high as 29, meaning that it achieves the flame-retardant requirement under a normal atmosphere, which is essential to the safety of lithium ion batteries. These features allow this novel gel polymer electrolyte to function as a high performance and high safety lithium ionic conductor as well as a separator for lithium-ion batteries.

Production of depolymerized lignin resin material from lignocellulosic biomass using acetone–water binary solution

The use of lignin, one of the main components of biomass, has only been for the recovery of energy through the combustion due to its complex structure. However, it needs to be used as more valuable material to make biorefinery feasible. In this study, the development of the lignin conversion method into resin materials was examined. Lignin was extracted from biomass with acetone/water binary solution at 220°C. The extracted lignin solution was treated under the severer condition for the depolymerization using flow reaction system. Through these two-step treatment, the extracted lignin was depolymerized to Mw<1000 fractions, which possessed many active sites for curing. More than 76.8% of lignin were recovered as depolymerized lignin through the whole treatment. The depolymerized lignin showed a fine activity of uniform curing with 10–15 per hundred resins (phr) of hexamine at 150°C. This resinification method of lignin was confirmed to be adaptive to some types of biomass, despite the belonging groups such as a coniferous tree, a broadleaf tree, or herbaceous biomass. One of thus produced resins was confirmed to be the competitive resin with a conventional phenolic novolac resin.

Synthesis of Triazole-functionalized Phenolic Resin and its Inherent Flame Retardant Property

A novel triazole-functionalized phenolic resin was developed, and its thermal and flame-retardant properties were investigated. The triazole group was incorporated as a pendant unit on the phenolic resin via copper- mediated click chemistry between propargylated phenolic resin and benzyl azide. The newly-developed triazole-functionalized phenolic resin showed higher thermal stability and char yield, together with a reduced total heat release (THR), than the non-functionalized bare phenolic resin, indicating enhanced flame retardancy for the triazole-functionalized phenolic resin. and superior mechanical and ablative properties. 1,2 Phenolic resins are generally prepared by reactions bet- ween formaldehyde and phenol in the presence of acid or base. When prepared by acid catalysis, they are normally called novolac-type resins. In these resins, the molar ratio of formaldehyde to phenol is less than 1, and substitution occurs mostly at the ortho position of the phenol. In contrast, base-catalyzed pathways produce more cross-linked struc- tures, and are called resole-type phenolic resins, with sub- stitutions at both ortho- and para-positions. Phenolic resins with improved thermal and pyrolysis characteristics are desirable for producing composites for thermo-structural applications. 3,4 Although conventional phenolic resins are already considered to be temperature- resistant polymers and are currently in use for the above- mentioned applications, some of the properties of phenolic resins need further improvement for meeting the ever- increasing performance requirements. With sufficient heat and oxygen, most organic polymers will burn. Fundamentally, four processes are involved in the polymer combustion cycle: heating, decomposition, ignition, and combustion. In order to increase its flame resistance, the polymer system should function to interrupt this cycle. 5 A

Performance of Graphite Filled Composite Based on Benzoxazine Resin. II. Decreasing the Moulding Time of the Composite

To put the fuel cell to practical use, it is necessary to reduce its cost for the production of the bipolar plate as one of the components in the cell. Decreasing the moulding (cure) time of the graphite filled composites as a bipolar plate can increase its productivity. In this study, we aimed to decrease the moulding (cure) time of graphite-filled composites based on benzoxazine resin for the bipolar plate. Therefore, phenol novolac resin was added to benzoxazine resin as a curing accelerator. Expanded graphite was used for the preparation of the graphite-filled composites. The composites were prepared by means of the compression moulding of mixtures of graphite and benzoxazine resin containing phenol novolac as a curing accelerator. The properties of the graphite filled composites based on benzoxazine resin containing phenol novolac as a curing accelerator were characterised by mechanical properties, gas permeability and electrical conductivity. As a result, the curing reaction of benzoxazine resin containing phenol novolac as a curing accelerator could proceed more rapidly than that of only benzoxazine resin, and the moulding (cure) time of the composite was decreased. It was found that phenol novolac was an effective moulding accelerator of the graphite filled composites based on benzoxazine resin, and that it could increase the productivity of the bipolar plate using the graphite filled composite based on benzoxazine resin. It was also found that graphite filled composites based on benzoxazine resin containing phenol novolac as a curing accelerator showed good gas impermeability, electrical conductivity and mechanical properties compared with those of the graphite-filled composites based on the conventional phenolic resins.