Cardanol-based novolac epoxy vinyl ester resin (CNEVER) was prepared by using 1:0.9
mol ratio of cardanol-based epoxidized novolac (CNE) and methacrylic acid. The reaction was carried out in the ...presence of triphenylphosphine (TPP) catalyst (1 phr by weight of the resin) and hydroquinone (200
ppm as inhibitor) at 90
°C in nitrogen atmosphere for about five hours to obtain a product with acid value
29 less than 10. The products were analyzed by Fourier-transform infra-red (FTIR), nuclear magnetic resonance (NMR) spectroscopic analysis and gel permeation chromatographic (GPC) analysis. The prepared CNEVER was cured in 60
min at 120
°C which was obtained by differential scanning calorimetric (DSC) analysis.
Cardanol-based epoxidized novolac vinyl ester resin (CNEVER) was synthesized by reacting cardanol-based epoxidized novolac (CNE) resin and methacrylic acid (MA) (CNE:MA molar ratio 1:0.9) in presence of triphenylphosphine as catalyst at 90
°C. The CNE resin was prepared by the reaction of cardanol-based novolac-type phenolic (CFN) resin and epichlorohydrin, in basic medium, at 120
°C. The CFN resin was synthesized by reacting cardanol (C) and formaldehyde (F) (C/F ratio
=
1:0.7) with
p-toluene sulphonic acid (PTSA) as catalyst (0.5
wt.%) at 120
°C for 7
h. The resin products were analyzed by Fourier-transform infra-red (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analysis. The number-average molecular weight of the prepared CNEVER was found to be 859
gmol
−1 as determined by gel permeation chromatographic (GPC) analysis. The resin was cured by using the mixture of resin, benzoyl peroxide, and styrene at 120
°C. The CNEVER resin was found to be cured in 60
min at 120
°C. Differential scanning calorimetric (DSC) technique was used to investigate the curing behaviour. Single step mass loss in dynamic thermogravimetric (TG) trace of CNEVER was observed. Thermal stability of the vinyl ester sample containing 40
wt.% styrene was the highest amongst all other prepared systems.
This work introduces coal char prepared by pyrolysis of subbituminous coal as a filler for compression-molded phenolic resin composites to improve the physical properties along with reducing material ...costs. The effects of filler concentration, particle size, and blending method on mechanical and thermal properties as well as morphology were comprehensively studied in comparison to reference materials. When simply blending resin and char powders, the highest compressive strength of 246 MPa with a Young's modulus of 5.0 GPa was reached using 50 wt% coal char, outperforming an equal amount of wood fiber (sawdust) as a filler with 198 MPa compressive strength and 3.2 GPa Young's modulus. Subsequently, different solvents were employed as dispersants to improve particle dispersion allowing for higher filler loads. Tetrahydrofuran (THF) enabled the best dispersion and led to compressive/tensile strengths reaching 288 MPa/75 MPa for 60 wt% coal char and 307 MPa/37 MPa for 70 wt% coal char. In addition, the phenolic/coal char composites showed a significantly higher thermal stability over the sawdust composite as well as a commercial phenolic composite. Water absorption studies also illustrated improved performance of coal char with and without the THF dispersant over sawdust in reducing moisture absorption. The findings of this work suggest that coal char has significant potential to be used as a filler in novolac composites for applications such as load-bearing building materials where high compressive strength, stiffness, thermal stability, water resistance, and low cost are required.
Novolac/silica nanocomposite aerogels are prepared through the sol–gel polymerization process under a solvent saturated vapor atmosphere. The silica phase is extracted from rice husk ash in the form ...of silica xerogel powder. Nanocomposite aerogels are then fabricated through sol–gel polymerization of novolac resin in the presence of silica xerogel powder. These nanocomposite aerogels are then converted to carbon/silica and carbon/silica/silicon carbide nanocomposite aerogels using pyrolysis and carbothermal reduction processes at 800 and 1500°C, respectively. Mercury porosimetry method is used for the evaluation of microstructure and mechanical properties of fabricated hybrid nanocomposite aerogels. Mercury porosimetry analysis and scanning electron microscopy results confirmed that the Pirard and Washburn theories are valid for the evaluation of aerogels' pore size distribution. The buckling intrusion mechanism is studied for all polymeric and carbon nanocomposite aerogels below transition pressure. The effect of heat treatment on the microstructural properties is also investigated by mercury porosimetry analysis. The Young's modulus values are determined using mercury porosimetry data and compression results. Based on our results, the Young's modulus of hybrid nanocomposite aerogels is not necessarily related to the density of aerogels.
•Novolac/silica nanocomposite aerogels were prepared by using sol–gel polymerization.•Sol–gel polymerizations were developed in the solvent saturated vapor atmosphere.•The silica phase of initial aerogel sol was extracted from rice husk ash (RHA).•Polymeric aerogels were successfully converted to carbon/silica and carbon/silica/silicon carbide aerogels.•The buckling intrusion mechanism was observed for all aerogels below Pt.
► Boron nitride (BN) particles were used to modify novolac resin. ► BN particles were pretreated by γ-aminopropyltriethoxysilane. ► The thermal conductivity trend of composite almost agrees with the ...predicted data from the Maxwell–Eucken model. ► At BN concentration of 80
wt.%, thermal conductivity value of composite is 4.5 times that of pure novolac resin. ► Combined use of the larger and smaller particles with a mass ratio of 1:2 provides the composites with the maximum thermal conductivity among the testing systems. ► The composite thermal property also increases with an increase in the BN concentration.
In this study, γ-aminopropyltriethoxysilane-treated boron nitride (BN) particles were used to modify novolac resin. The effect of varying the BN concentration, particle size, and hybrid BN fillers with the binary particle size distribution on the thermal conductivity of the composites was investigated. Scanning electron microscopy (SEM) imaging showed homogeneously dispersed treated BN particles in the matrix. Furthermore, the thermal conductivity increased as the BN concentration was increased. This behavior was also observed when the filler size was increased. Experimentally obtained thermal conductivity values agree with the predicted data from the Maxwell–Eucken model well at less than 70
wt.% BN loading. A larger particle size BN-filled novolac resin exhibits a higher thermal conductivity than a smaller particle size BN-filled one. The combined use of 0.5 and 15
μm particles with a mass ratio of 2:1 achieved the maximum thermal conductivity among the testing systems. The thermal resistance properties of the composites were also studied.
Traditional novolac resin uses formaldehyde and an excess of phenol under an acid catalyst which has a remarkable production and wide applications, however, the polymerization and its curing reaction ...are highly exothermic and heat generation with the release of harmful gases (formaldehyde and phenol) link to a high potential of thermal runaway hazard and the possibility of explosions in resin factories. To make a sustainable novolac-type resin, the water-insoluble fraction of bio-oil glyoxal (BOG) resin was utilized as an ideal phenol bioresource. The safety criteria of renewable resins polymerization and its curing reaction were investigated using the Differential Scanning Calorimeter (DSC) and evaluated by comparing the critical runaway conditions with those of traditional non-renewable resins. The reaction mechanism of the novolac resin synthesis and curing reaction were discussed as well. The results indicate that the use of bio-oil can reduce the heat risk of polymerization reactions. The introduction of biochar for the first time in curing reactions has shown a potential beyond anticipation in reducing the heat risk of curing reactions.
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Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and ...automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.
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•Catalytic curing of propargylated novolac with Ni(II) and Cu(II) salts resins was studied.•Probable catalysis mechanism of Cu(II) salts was discussed.•Curing process for bulky ...composite parts was simulated based on curing kinetic study.
Catalysts for propargylated novolac resins (PN) curing based on stable Ni and Cu salts were studied. Concentration dependences of catalytic activities for both catalyst types were investigated. For the first time copper salts were suggested as catalysts for PN curing and catalytic action mechanism was suggested based on model experiments. Catalytic kinetic study followed by computer modeling allowed to simulate the curing process avoiding overheating during manufacturing of bulky composite part. A sufficient decrease both in processing time and temperature was demonstrated even under smoother thermal conditions while using the Ni catalysis. It was also shown that catalyzed curing proceeded more uniformly in the volume of bulky parts.
•Energy efficient protocol has been developed for the synthesis of cardanol based novolac resin (CBN).•Polymeric synthesis has been accomplished at room temperature using acoustic cavitation.•For the ...synthesis of CBN, time spam of the reaction has been reduced from 5 h (300 min) to 30 min and temperature from 120 °C to room temperature using US method.
The present study deals with synthesis of cardanol-cased novolac (CBN) resin by the condensation reaction between cardanol and formaldehyde using acoustic cavitation. It is a step-growth polymerization which occurs in the presence of an acid catalyst such as adipic acid, citric acid, oxalic acid, sulphuric acid and hydrochloric acid. CBN was also synthesised by a conventional method for the sake of comparison of techniques. The effect of molar ratio, effect of catalyst, effect of different catalyst and effect of power on the conversion to CBN has been studied. The synthesised CBN was characterized using the Fourier Transform Infra Red Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (NMR) Spectroscopy and Thermogravimetric Analysis (TGA). The reaction was monitored by the Acid value, free formaldehyde content and viscosity of the synthesised product. The reaction time required for the conventionally synthesised CBN was 5 h (300 min) with 120 °C as an operating temperature while sonochemically the time reduced to 30 min at room temperature. The amount of time and energy saved can be quantified. Ultrasound facilitated synthesis was found to be an energy efficient and time-saving method for the synthesis of novolac resin.
The focus of this investigation is based on the absence of previous study on shape stability, swelling and hydrophobicity in polar and non-polar solvents and antibacterial properties of epoxy-novolac ...acrylate (ENA)/multi-walled carbon nanotubes (MWCNTs)-3-aminopropyl triethoxysilane (APTES)-ZnO (ENA-MWCNT-A-ZnO) hybrid coating films. Hybrid coating films were prepared by mixing of ENA with photo-initiator (2-hydroxy 2-methyl phenyl propane 1-one), Trimethylolpropane triacrylate (TMPTA) and multi-walled carbon nanotubes-APTES-ZnO (MWCNTs-A-ZnO) concentration (1 and 2 wt %). The hybrid films were characterized by electron microscopy to study surface and bulk morphologies. Spectroscopy studies were carried out to determine the effect of MWCNTs-A-ZnO incorporation on intermolecular interactions, degree of crystallinity and extent of crosslinking, respectively. The extent of MWCNTs-A-ZnO loading on the morphological structure, melt viscosity, glasstransition temperature, tensilestrength and antibacterial performance of the coating films was evaluated. The glass transition temperature, tensile strength and young's modulus of the ENA are significantly increased with increasing MWCNTs-A-ZnO concentration. Resilient shape stability was observed in water as well as in various organic solvents. The S. aureus bacteria shows higher degree of inhibition compared to E. coli inhibition zone and increasing of E. coli inhibition zone with increasing concentration of MWCNT-A-ZnO nanoparticles.
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•Designed and prepared hybrid coatings by Michael addition and radical polymerization reaction.•FTIR, Raman, SEM, TEM, TGA, DSC, UTM and DMTA measurements were used to characterize hybrid coating.•The S. aureus bacteria shows higher degree of inhibition compared to E. coli inhibition zone.•Resilient shape stability was observed in water, methanol, acetone and chloroform.•The equilibrium swelling ratio of coating films is unpredictably taking high immersion time.
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