Phenolic Composites Research Articles

3D needle-punched carbon/quartz fabric reinforced nanoporous phenolic composites with co-optimized mechanics, insulation and ablation

Phenolic composites are the most reliable ablatives for thermal protection system, but integrating low density, good insulation and excellent mechanical/anti-ablation performance remains challenging. Here, a density-porosity trade-off method for synthesizing mid-density and high-strength phenolic composites is proposed. This method uses 3D needle-punched preforms to reinforce nanoparticle phenolic matrix. Proper compromise between porosity and density enables phenolic matrix to combine excellent thermal insulation and acceptable mechanical properties. And in-situ micro-CT results indicate that 3D needle-punched preforms can greatly improve the mechanical performance by restricting crack propagation from felt piles to woven piles. Furthermore, the mechanical, insulative and ablative properties can be optimized using hybrid carbon/quartz preforms. The resultant composites exhibit mid-densities of ∼0.9 g/m3 with integrated performance of high tensile strength (70–120 MPa), low thermal conductivity (0.08–0.12 W/(m·K)) and good ablation resistance. These schemes will encourage the development of phenolic composites that can withstand different heat fluxes.

Low-Velocity Impact, Free-Fall Drop Test of Prototype, and Failure Analysis of Hybrid Palm / Kenaf Reinforced MWCNT Phenolic Composites

ABSTRACT The research’s aim is to investigate the energy absorption, free-fall drop analysis, and failure analysis of Palm (P)/kenaf (K) fiber-reinforced MWCNT-phenolic composites. 3P:7K reinforced MWCNT–phenolic composites were made using manual mixing and hot pressing at 150°C with a pressure of 10 tonnes. Energy absorption was investigated using a drop weight impact tester. Free-fall drop test was performed to analyze the performance of the aircraft tray table prototype. Non-destructive testing was carried out to investigate the damage mechanism. The results demonstrate that as the impact energy increased from 1.50 J to 3.0 J, the crack length increased. There is a difference of 3% to 15% in the crack sizing between dye penetration and Digital Detector Array (DDA), indicating that DDA is more accurate. In the free-fall drop test, small cracks were detected in the dye penetration method on the prototype. The DDA approach, however, did not reveal any defects. The agglomerations were observed through DDA and Computed tomography. In this study, the hybrid CR/kenaf reinforced MWCNT modified phenolic composites exhibit superior performance that can act as an efficient and eco-friendly material for aircraft tray table application by preserving natural resources.

Experimental and theoretical evaluation of synthetized cobalt oxide for phenol adsorption: Adsorption isotherms, kinetics, and thermodynamic studies

Water pollution by phenolic composites is considered a major environmental problem. Therefore, their removal by adsorption is of great practical importance. In this paper, the synthesized cobalt oxide Co3O4 was used as an adsorbent for the adsorption of phenol in an aqueous medium. A DFT calculation has been carried out to determine the sites accountable for the interactions in phenol molecule, and molecular dynamics (MD) simulations were used to understand the mechanism of interaction between phenol molecule and Co3O4 surface. The developed adsorbent was characterized by physicochemical methods including XRD, SEM, FT-IR, and BET. The maximum adsorption capacity was observed at pH = 4 with an adsorbed amount of 8.10 mg/g and (R = 98 %). Furthermore, to probe the adsorption action of the phenolic emulsion on the cobalt oxide face, theoretical simulations based on MD (molecular dynamics) and DFT (viscosity functional proposal) were performed. The DFT results verified the chemisorption ascendancy while the MD simulations indicated an increased trade of Co3O4 with phenol in the presence of detergent due to water-bridged H- bonds.

Multi‐walled carbon nanotubes/carbon fiber fabric multiscale hybrid materials for improving the mechanical and tribological properties of phenolic resin composites

AbstractMulti‐walled carbon nanotubes (MWCNT)/carbon fiber fabric multiscale hybrid materials were prepared by grafting MWCNT on carbon fabric surface via heating grafted method to improve the mechanical and tribological properties of phenolic resin composites. Field emission scanning electron microscopy, Raman spectrometer, and X‐ray photoelectron spectroscopy were used to analyze the surface properties of carbon fiber. The results shown that the tensile strength of composites modified by 0.15 wt% MWCNT was 38% higher than that of unmodified composites. The wear rates decreased from 3.31 × 10−14 m3 (N·m)−1 for unmodified composites to 0.68 × 10−14 m3 (N·m)−1 for 0.15 wt% MWCNT reinforced composites. The reason was that the uniformly distributed MWCNT could increase interface interaction and mechanical interlocking between carbon fiber fabric and resin matrix.

Enhanced electrochemical performance of the fluidization separation graphite powders from waste power lithium-ion batteries by phenolic resin carbon coated

The recycling of waste lithium batteries (LIBs) is important for the healthy development of the LIBs industry. In this work, a column fluidized bed was designed to recover graphite powder from waste LIBs, and the phenolic resin-coated recovered graphite powder composites ware prepared by liquid-phase impregnation-carburization method, which effectively repaired the pores and defects on the surface of recycled graphite powders. The composites exhibited better Li storage performance than the recovered graphite powders. When the current density was 0.05 A/g, the composite obtained at 5% phenolic resin coating displayed a high reversible capacity of 451.0 mAh/g and an initial coulombic efficiency of 68.0%. The specific capacity was maintained at 131.9 mAh/g at a higher current density 1.0 A/g, the reversible capacity gradually increased from 464.4 to 546.1 mAh/g after 100 cycles at a current density of 0.1 A/g, indicating outstanding rate performance and excellent cycling stability. • Recovery and reuse graphite powders from waste lithium batteries is studied. • A column fluidized bed can recover the grade of graphite powders with 96.42% • Phenolic resin carbon coating technology can repair the pores and defects. • Repaired graphite powders have a high capacity and first coulomb efficiency.

Cotton waste and nanoclay‐based phenolic novolac epoxy composites and evaluation of their properties

AbstractIn this study, two types of biobased epoxy composites were prepared by using only alkali‐treated cotton waste (CtW), or with the nanoclay (NC) in the form of hybrid reinforcement. Phenol novolac‐type epoxy resin (EPN) was used as a matrix. Untreated (CtW) and alkali‐treated (NaOH‐CtW) particles were characterized by scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy (EDX). The average size for NC was determined as 3838 nm. Composites were prepared at 10–50 wt% NaOH‐CtW and 20 wt% NaOH‐CtW/(1–2–3–4–5) wt% NC ratios. The morphology of the composites was investigated using SEM. The composites' properties were determined by applying thermogravimetric analysis (TGA), and various tests (tensile, hardness, water sorption, and surface contact angle measurement). The tensile strength of pure EPN was 96.6 MPa, while it changed in the range of 74–98 and 81–106 MPa for NaOH‐CtW and hybrid composites, respectively. All hybrid composites exhibited higher Young's modulus values (7.7–8.9 GPa). Thermal values of hybrid composites were found higher and their char percentages varied in the range of 28.9–30.3%. NaOH‐CtW increased the water sorption of the epoxy matrix from 0.59% up to 6% by 50 wt%. In contrast, a decrease in water sorption of NC composites was observed.

Effect of Filler Content on Flexural and Viscoelastic Properties of Coir Fibers and Argania Nut-shells Reinforced Phenolic Resin Composites

Effect of Filler Content on Flexural and Viscoelastic Properties of Coir Fibers and Argania Nut-shells Reinforced Phenolic Resin Composites

2.5D quartz fabric reinforced nanoporous phenolic composites with weakened heat transfer and optimized mechanical properties

Phenolic-based composites are the most promising ablative thermal protection materials for space applications, but optimizing their thermal insulation performance while maintaining high strength remains extremely challenging. Herein, phenolic-based composites with co-optimized thermal insulation and mechanical properties are prepared via 2.5D quartz fabric reinforcing nanoporous phenolic. The pore size of phenolic matrix is efficiently refined to ∼35 nm by adjusting resin concentration, enabling composites to exhibit high density but low thermal conductivity by enhancing Knudsen diffusion. Finite element analysis shows that low braiding angle of 2.5D fabric can further weakening heat transfer of composites due to anisotropic thermal conductivity of fiber yarns. In-situ X-ray micro-CT results indicate that 2.5D fabrics can reinforce composites through interwoven yarns, and straighter weft yarns result in higher strength along weft direction than that along warp direction. Compared with dense quartz/phenolic composite, the resulting composites exhibit 16.5% lower density (1.32 g/cm3), 58.8% lower thermal conductivity (0.21 W/(m·K), ≥372.7% higher tensile strength (≥182.0 ± 9.6 MPa) and comparable ablation resistance. The present results will further advance the application of phenolic-based composites in more extreme re-entry environments.

Thermal degradation, visco-elastic and fire-retardant behavior of hybrid Cyrtostachys Renda/kenaf fiber-reinforced MWCNT-modified phenolic composites.

Natural fibers have emerged as a potential alternate to synthetic fibers, because of their excellent performance, biodegradability, renewability and sustainability. This research has focused on investigating the thermal, visco-elastic and fire-retardant properties of different hybrid Cytostachys Renda (CR)/kenaf fiber (K) (50/0; 35/ 15, 25/25, 15/ 35, 0/50)-reinforced MWCNT (multi-walled carbon nanotubes)-modified phenolic composites. The mass% of MWCNT-modified phenolic resin was maintained 50 mass% including 0.5 mass% of MWCNT. In order to achieve homogeneous dispersion ball milling process was employed to incorporate the MWCNT into phenolic resin (powder). Thermal results from thermogravimetric analysis and differential scanning calorimetric analysis revealed that the hybrid composites (35/15; 35 mass% CR and 15 mass% K) showed higher thermal stability among the composite samples. Visco-elastic results revealed that kenaf fiber-based MWCNT-modified composites (0/50; 0 mass% CR and 50 mass% K) exhibited higher storage and loss modulus due to high modulus kenaf fiber. Fire-retardant analysis (UL-94) showed that all the composite samples met H-B self-extinguishing rating and exhibited slow burning rate according to limiting oxygen index (LOI) test. However, (15/35; 15 mass% CR and 35 mass% K) hybrid composites showed the highest time to ignition, highest fire performance index, lowest total heat release rate, average mass loss rate, average fire growth rate index and maximum average rate of heat emission. Moreover, the smoke density of all hybrid composites was found to be less than 200 which meets the federal aviation regulations (FAR) 25.853d standard. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was carried out to select an optimal composite sample considering the thermal, visco-elastic and fire-retardant behaviors. Through TOPSIS analysis, the hybrid (15/35; 15 mass% CR and 35 mass% K) composite sample has been selected as an optimal composite which can be used for high-temperature aircraft and automotive applications.

Ag nanoparticle decorated graphene for improving tribological properties of fabric/phenolic composites

In the present study, graphene nanosheets (GNS) supporting monodispersed Ag nanoparticles (GNS/Ag) hybrid was constructed via an in-situ synthesis. The enhancement mechanism of friction and wear performance of Kevlar/PTFE (Poly-p-phenylene terephthamide)/(Polytetrafluoroethylene) phenolic composites reinforced by GNS/Ag hybrid was investigated by virtue of macroscopic experiments and microscopic molecular (MD) simulation. The results found that Ag nanoparticles were homogeneously anchored on the GNS surfaces. When 9 wt% GNS/Ag hybrid was incorporated into fabric composites, the friction coefficient and wear rate of Fabric-9GNS/Ag decreased by 40 % and 72 % because of synergistic enhancement of GNS and Ag nanoparticles. The MD simulation demonstrated that GNS/Ag hybrid had a strong interaction with molecular chains of PTFE, Kevlar and phenolic resin.

Assessment of a 3D ablation material response model for lightweight quartz fiber reinforced phenolic composite

AbstractTo understand the ablation mechanism of materials is crucial for the design of thermal protection system (TPS) for manned reentry vehicles. To investigate the thermal behavior of lightweight quartz fiber reinforced phenolic (LQP) composite subjected to an aerodynamic hyper‐thermal environment, a 3D ablation material response model for the LQP composite is developed with surface and volume ablation in consideration. It is used to predict surface and back temperature, linear ablation velocity, and quality loss rate of the material. The 3D temperature field, pyrolysis degree, gas flow, and pressure field are analyzed as well. To evaluate the accuracy of the model, an ablation test of oxyacetylene flame is adopted on the LQP composite. In the ablation process, the pyrolysis gases propagate primarily through the surface primarily and through the sidewall afterwards. The gas pressure peaks at the early stage rather than increasing constantly. The analysis of thermal insulation mechanism of the LQP composite indicates that the radiation and heat blockage effect are the primary factors to improve the ablation resistance, accounting for 50.0% and 37.3% of the improvement, respectively. The low thermal conductivity determines the admirable thermal insulation performance. The surface temperature of material can be reduced by introducing high emissivity powder into the material, preparing coating on the surface, and adjusting the content of phenolic and silica fiber.

The effect of barite addition and graphite particle size on the specific abrasion of fly-ash/phenolic composite for brake lining application

Annually, million tons of fly-ash and bottom fly-ash is a waste of coal power plant. Fly ash contains Iron-oxide, alumina and silica. Those hard particle makes fly-ash can be used as a reinforcement in polymer composite. This composite is a wear resistance material and can be used as material for brake lining application. Fly ash reinforced phenolic composite has a low specific abrasion. The composite for brake lining material consisted of the reinforcement, friction modifier, solid lubricant and filler. Graphite is used as solid lubricant while barite is used as filler. Many research were carried out research on the particle size effect on the composite mechanical properties. However the size different between the constituent in composite has not investigated. Also the optimal barite weight fraction has not being observed. The composite was made by mixing all of the constituent, pressing in the mold and curing. The result show that the graphite particle size ? 150 mm has the lowest specific abrasion. The observation using scanning electron microscope shows that the composite contained small particle of ? 56 mm tends to agglomerate than the composite contained larger particle of ? 150 mm. the composite contained 15% barite has the lowest specific abrasion. The micrograph of scanning electron microscope shows the mixed of phenolic and barite evenly covered the graphite and fly-ash particles.

In-situ noncontact measurement system for nozzle throat deformation in high-temperature gas heating via laser speckle digital image correlation with wavelet smoothing of displacement field

The shape of nozzle throat in an engine could greatly change the amount of thrust or heat transfer performance. To in-situ evaluate nozzle throat deformation in high-temperature gas heating tests, a non-contact full-field deformation measurement system via laser speckle Digital Image Correlation with wavelet smoothing of displacement field is proposed. For high-temperature thermal radiation suppression, high-power laser speckle pattern is used for digital image correlation calculation and multi-step filters with polarizers are used. A displacement field wavelet smoothing algorithm is proposed to mitigate imaging distortion caused by airflow disturbance. Gas heating experiments on a nozzle sample made of carbon fiber high silica phenolic resin composites were carried out. The full-field displacement measurement results show that compared with the commonly used air blade method, the proposed method can provide smoother displacement field for deformation evaluation, the displacement measurement difference of the proposed method and a dial indicator was within 0.01 mm.

High mechanical strength and low ablation rate of phenolic resin composites incorporated with polyhedral oligomeric silsesquioxane‐modified graphene oxide

AbstractHybrid composites of phenolic resin are prepared by incorporating graphene oxide (GO) functionalized with aminophenyl silsesquioxane (NH2‐OPS) for different functionalities. The covalent grafting of NH2‐POSS to GO is favorable for its homogeneous dispersion in the polymer matrix. For this purpose, GO is modified with NH2‐OPS to obtain GO‐3NH2‐OPS (GP‐3), GO‐5NH2‐OPS (GP‐5), GO‐8NH2‐OPS (GP‐8), according to the functionality of NH2‐OPS, respectively. The GP samples are then incorporated into phenolic resin (PR) to obtain PR/GP composites. The successful modification for GO with NH2‐OPS is confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy and specific surface and pore size analysis. The thermogravimetric analysis results show that the thermal stabilities of GP‐3, GP‐5 and GP‐8 are significantly increased compared with pure GO. Furthermore, the mechanical and ablative properties of the PR/GP composites are effectively enhanced. In particular, with the addition of 0.5 wt% GP‐5, the linear ablation rate of the PR/GP‐5 composite is reduced by 55.5% from 0.128 to 0.057 mm/s and the flexural strength is increased by 80.6% from 47.74 to 86.23 MPa, compared with pure PR.

Thermal and acoustic properties of silane and hydrogen peroxide treated oil palm/bagasse fiber based biophenolic hybrid composites

AbstractThe consequence of 2% v/v silane‐treated and 4% v/v H2O2‐treated upon thermal and acoustic behavior of hybrid oil palm EFB (OPEFB) and sorghum stalks bagasse fiber (SCB) reinforced phenolic composites for wall thermal insulation application is discussed in this paper. Hand lay‐up approach was adopted to manufacture plain and hybrid composites with diverse formulation ratios such as 70:30 (7OPEFB:3SCB), 50:50 (5OPEFB:5SCB), and 30:70 (3OPEFB:7SCB). The experimental samples were manufactured with a purpose density of 0.5 g/cm3. Plain and hybrid composites were investigated for thermal analysis and thermal conductivity testing. Impedance tubes were used for acoustic behavior analysis of composites. Hybridization of H2O2 treated HT 50:50 (5OPEFB:5SCB) showed greater thermal cohesion with a final residual of 58.69%, followed by hybridization of silane‐treated ST 50:50 (5OPEFB:5SCB) with a residual of 45.10%. This study looks at four distinct air gap thicknesses (0 mm, 10 mm, 20 mm, and 30 mm). The results reveal that silane‐treated ST 50:50 (5OPEFB:5SCB) hybrid composites and H2O2‐treated HT 50:50 (5OPEFB:5SCB) hybrid composites improved sound absorption coefficients more than 0.50. Thus, we concluded that thermal and sound absorption performances of hybrid composites from agro waste promise an environmentally friendly alternative solution in wall building material production.

Effect of cure temperature on the thermal degradation, mechanical, microstructural and moisture absorption behavior of vacuum‐only, carbon‐fiber reinforced phenolic composites

AbstractPhenolic resin is the material of choice used for composite liners in solid rocket motor nozzles. We investigate the effect of the cure conditions (94, 116, and 155°C) on vacuum only (VO) processed composite mechanical, thermal, and microstructural changes. Although the Tg's correlated with the processing conditions, mechanical properties showed unexpected non‐linear degradation after 94°C processing. This difference is primarily due to the lower cure state of the resin, which results in poor fiber/matrix coupling and is further magnified by the reduced degree of consolidation observed in VO parts. Elevated thermal exposure was shown to generate larger tensile strains in the out of‐plane direction for the 94°C composites when compared to the other conditions. This resulted in significant increases in crack density, porosity, and delamination due to an increased volume of degradation by‐products, while the higher temperature cured composites maintained good consolidation. Even though all three cure states appeared to display equivalent moisture absorption saturation levels based on weight measurements, the 94°C cured sample was shown to partially dissolve in moisture during humidity exposure, which translated to even higher saturation levels. This larger net absorption resulted in a larger drop in Tg for the 94°C cured material and thus resulted in a more severe thermal mechanical response than the other saturated specimens. This emphasizes how a reduction in cure state will not only affect thermal and mechanical performance but will also translate to a greater degree of degradation than more highly cured specimens, when exposed to humid environments.

Oxidation Behavior of Carbon Fibers in Ceramizable Phenolic Resin Matrix Composites at Elevated Temperatures.

Carbon fiber fabric-reinforced phenolic resin composites are widely used as thermal protection materials for thermal protection systems in hypersonic vehicles and capsules. In this work, carbon fiber fabric-reinforced boron phenolic resin composites modified with MoSi2 and B4C were prepared via a compression molding technique. The high-temperature performance of the composites as well as the oxidation behavior of the carbon fibers was studied. The results indicate that the incorporation of B4C improves the performance of composites at high temperatures. The residual weight rate of composites with 15 phr B4C (BP-15) sufficiently increased from 23.03% to 32.91% compared with the composites without B4C (BP-0). After being treated at 1400 °C for 15 min, the flexural strength of BP-15 increased by 17.79% compared with BP-0. Compared with BP-0, the line ablation rate and mass ablation rate of BP-15 were reduced by 53.96% and 1.56%, respectively. In addition, MoSi2 and B4C particles had a positive effect on the oxidation of carbon fibers in the composites. After treatment at 1400 °C, the diameter of the as-received carbon fiber was reduced by 31.68%, while the diameter of the carbon fiber in BP-0 and BP-15 decreased by 15.12% and 6.14%, respectively. At high temperatures, the liquid B2O3 from B4C and MoSi2-derived complex-phase ceramics (MoB, MoB2, Mo2C, Mo4.8Si3C0.6) acted as an oxygen barrier, effectively mitigating the oxidation degree of the carbon fibers.

Ablative properties, thermal stability, and compressive behaviour of hybrid silica phenolic ablative composites.

Silica phenolic composites are used as thermal protection systems for high temperatures applications like atmospheric re-entry modules, rocket nozzles etc. Lightweight silica phenolic composites (SPGB) were developed using chopped silica fibre, phenolic matrix, and hollow glass microspheres through a compression moulding technique to achieve a cost advantage in thermal protection systems. Ablative properties were evaluated using an Argon plasma jet at a stagnation heat flux of 500 W/cm2. The mass-loss and erosion rates under plasma exposure reduced up to 48% and 32%, respectively, with the addition of hollow glass microspheres. The heat of ablation of composites increased up to 33%. The thermal degradation behaviour of raw materials and SPGB composites was investigated through thermogravimetric analysis, and the scientific know-how was established. Compressive behaviour under uniaxial loading was evaluated, and the theoretical model for the developed three-component composite was established.

Tribological performance evaluation of slag waste filled phenolic composites for automotive braking applications

AbstractSlag waste‐filled phenolic resin‐based automotive brake friction composites were formulated, fabricated, followed by mechanical, physical characterization, and tribo‐evaluation. According to economic commission for Europe regulation, the tribological performance of the composites was evaluated on a Krauss friction‐testing machine. The increase in slag waste content led to increased physical properties such as density, porosity, ash contents, and compressibility, whereas hardness, acetone extraction, and shear strength increased with increased phenolic resin content. The fade and friction performance has been observed to be highly dependent on the slag waste content, that is, both followed a consistent decrease with the increase in the phenolic resin content, whereas the frictional fluctuations have been observed to decrease with the increase in slag waste content. In particular, the composites containing 65 wt% slag waste and 5 wt% phenolic resin showed the highest friction coefficient (0.406), lowest fade (20.44%) and frictional fluctuation (0.209), but the wear (10.80 g) and disc temperature rise (618°C) remains highest. Composite with the lowest slag waste content of 50 wt% combined with the highest phenolic resin of 20 wt% showed higher recovery performance (120.63%), lowest wear (4.45 g) and disc temperature rise (536°C), but exhibits lowest friction coefficient (0.315) and friction stability (0.79) along with highest friction variability (0.60) and fluctuations (0.238). Friction and wear data analysis revealed the predominance of the fade factor for friction performance while the fade factor and disc temperature‐induced results significantly influence the wear performance. The worn surface micrograph showed higher phenolic resin‐filled composites form smooth contact plateaus that successfully reduced wear.

Micro-fracture behaviors of needled short-chopped fiber reinforced phenolic aerogel composites based on in-situ X-ray micro-CT

Needled short-chopped fiber reinforced phenolic aerogel composites (PAC) are the most promising thermal protection materials for space applications. However, the complex microstructures deriving from the irregular needling yarns severely limits the revealing of their fracture mechanisms. Herein, for the first time, the micro-fracture behaviors of PAC are innovatively revealed using in-situ X-ray micro-CT under tensile loading. Furthermore, the high-precision finite element analysis of stress evolution is realized by establishing PAC model based on the micro-CT slices. The results indicate that the needling yarns will result in the enrichment of resin aerogel, leading to the stress concentration and micro-cracks initiation during loading. And the needling yarns can effectively hinder the separation and orientation of short-chopped fibers and retard the stress transmission between fibers and matrix, which are the main strengthening mechanisms of PAC. The present results will give references for revealing the fracture mechanisms of composites enhanced by needled fibers.