Magnetocaloric properties of phenolic resin bonded La(Fe,Si)13-based plates and its use in a hybrid magnetic refrigerator

We present a simple hot press-based method for processing La(Fe,Si)13-based compounds consisting of La–Fe–Co–Si–C particles and phenolic resin. The magnetic entropy change △S per unit mass for the La Fe_(10.87)Co_(0.63)Si_(1.5)C_(0.2)/phenolic resin compounds have nearly the same magnitude with the base materials. With the content of phenolic resin of 5.0 wt%, the compound conductivity is 3.13 W·m^(-1)·K^(-1). In order to measure the cooling performance of La(Fe,Si)13-based compounds,the La(Fe_(11.6-x)Co_(x))Si_(1.4)C_(0.15)(x =0.60, 0.65, 0.75, 0.80, 0.85)/phenolic resin compounds were pressed into thin plates and tested in a hybrid refrigerator that combines the active magnetic refrigeration effect with the Stirling cycle refrigeration effect. The test results showed that a maximum cooling power of 41 W was achieved over a temperature span of 30 K.

Preparation and Properties of Phenolic Resin/Montmorillonite Intercalation Nanocomposites

Phenolic resin/montmorillonite intercalation composites were prepared by using the methods of pressing intercalation and melt intercalation.Properties and structure of the composites were investigated by using XRD,TG and test of softening point.It is indicated that both the pressing intercalation and melt intercalation can be used to prepare the phenolic resin/organo-montmorillonite intercalation nanocomposites.Compared with phenolic resin,the intercalation nanocomposites have better heat-resistance,higher decomposition temperatures and less thermal weight-loss.However,these two intercalation methods have different effects on the softening point of the intercalation nanocomposites.Pressing intercalation almost does not affect the softening point of the intercalation nanocomposites,while melt intercalation significantly increases the softening point of the intercalation nanocomposites, probably due to the chemical actions happening in the process of melt intercalation.

Synthesis of benzoxazine-based phenolic resin containing furan groups

A novel benzoxazine-based phenolic resin containing furan groups（PFB） was synthesized via simple two-step reactions and the structure of PFB was confirmed by FTIR and ~1H NMR spectra.Differential scanning calorimetry（DSC） showed that the polybenzoxazine cured from PFB had good heat resistance and lower polymerization temperature compared with that of benzoxazine-based phenolic resins.

STUDY ON THE THERMODYNAMIC PROPERTIES OF ADSORPTION OF ETHYL BENZOATE AND DIETHYL PHTHALATE BY PHENOLIC RESIN ADSORBENTS

This paper presents experimental observations on the adsorption of individual solutes by a simple thermodynamic framework, and the equilibrium adsorption of ethyl benzoate and diethyl phthalate on phenolic resin adsorbent in hexane solutions within the temperature range of 293-313 K. The experimental results show that the Freundlich adsorption law is applicable to the adsorption of ethyl benzoate and diethyl phthalate on the adsorbent, since all the correlative factors R' are larger than 0.99. The negative values of all the isosteric adsorption enthalpies for ethyl benzoate and diethyl phthalate indicate that they undergo exothermic processes, while their magnitudes (19-28 kJ/mol) manifest a hydrogen bonding sorption process. Other thermodynamic properties: the free energy changes and the entropy change associated with the adsorption have been calculated from the Gibbs adsorption equation and the Gibbs-Helmholtz equation

Curing mechanism of alkaline phenolic resin with organic ester

To study the curing mechanism of alkaline phenolic resin with organic ester, three esters were chosen to react with three systems — alkaline phenolic resin, potassium hydroxide aqueous solution containing phenol, and potassium hydroxide aqueous solution. The variations of pH, heat release and gel pH during the reactions were monitored and measured. Infrared spectroscopy(IR) and thermal gravity analysis(TG) techniques were used to characterize the curing reaction. It was found that organic ester is only partially hydrolyzed and resin can be cured through organic ester hydrolysis process as well as the reaction with redundant organic ester. The sequential curing mechanism of alkaline phenolic resin cured by organic ester was identified as follows: a portion of organic ester is firstly hydrolyzed owing to the effect of the strong alkaline; the gel is then formed after the pH decreases to about 10.8-10.88, meanwhile, the redundant organic ester(i.e. non-hydrolysis ester) starts the curing reaction with the resin. It has also been found that the curing rate depends on the hydrolysis velocity of organic ester. The faster the hydrolysis speed of the ester, the faster the curing rate of the resin.

Application conditions for ester cured alkaline phenolic resin sand

Five organic esters with different curing speeds: propylene carbonate(i.e. high-speed ester A); 1, 4-butyrolactone; glycerol triacetate(i.e. medium-speed ester B); glycerol diacetate; dibasic ester(DBE)(i.e. lowspeed ester C), were chosen to react with alkaline phenolic resin to analyze the application conditions of ester cured alkaline phenolic resin. The relationships between the curing performances of the resin(including pH value, gel pH value, gel time of resin solution, heat release rate of the curing reaction and tensile strength of the resin sand) and the amount of added organic ester and curing temperature were investigated. The results indicated the following:(1) The optimal added amount of organic ester should be 25 wt.%-30 wt.% of alkaline phenolic resin and it must be above 20 wt.%-50 wt.% of the organic ester hydrolysis amount.(2) High-speed ester A(propylene carbonate) has a higher curing speed than 1, 4-butyrolactone, and they were both used as high-speed esters. Glycerol diacetate is not a high-speed ester in alkaline phenolic resin although it was used as a high-speed ester in ester cured sodium silicate sand; glycerol diacetate and glycerol triacetate can be used as medium-speed esters in alkaline phenolic resin.(3) High-speed ester A, medium-speed ester B(glycerol triacetate) and low-speed ester C(dibasic ester, i.e., DBE) should be used below 15 °C, 35 °C and 50 °C, respectively. High-speed ester A or lowspeed ester C should not be used alone but mixed with medium-speed ester B to improve the strength of the resin sand.(4) There should be a suitable solid content(generally 45 wt.%-65 wt.% of resin), alkali content(generally 10 wt.%-15 wt.% of resin) and viscosity of alkaline phenolic resin(generally 50-300 mPa·s) in the preparation of alkaline phenolic resin. Finally, the technique conditions of alkaline phenolic resin preparation and the application principles of organic ester were discussed.

PREPARATION AND PHOTOSENSITIVITY OF WATER SOLUBLE PHENOLIC RESINS CONTAINING ACRYLOYL AND QUATERNARY AMMONIUM CHLORIDE GROUPS

New water soluble and photocrosslinkable prepolymers containing acrylate and quaternary ammonium salt groups were synthesized from epoxy phenolic resin via ring-opening reaction with acrylic acid and with aqueous solution of triethylamine hydrochloride successively. The second reaction needs no phase transfer catalyst to accelerate, since the product formed can act as a phase transfer catalyst. The prepolymer obtained contains both photocrosslinkable acrylate groups and hydrophilic quaternary ammonium salt groups. Optimum conditions for these reactions were studied. The photosensitivity of the prepolymer was also investigated. The effects of different photoinitiators, different crosslinkable diluent monomers and amine accelerator on the photosensitivity of the prepolymer were compared. The photoinitiator of hydrogen abstraction type is still effective without using amine or alcohol as accelerator, because the prepolymer contains a H beside the OH groups formed in the ring-opening reactions.

Ceramification of Composites of MgO-Al_(2)O_(3)-SiO_(2)/Boron Phenolic Resin with Different Calcine Time

The ceramifiable polymer composite of MgO-Al_(2)O_(3)-SiO_(2)/boron phenolic resin(MAS/BPF)with 40wt%of inorganic fillers was calcined at 1200℃for different time to promote ceramification of ceramifiable composite and improve heat resistance.The effects of different calcine time on the macroscopical morphology,mass loss,phase evolution,microstructure and chemical bond evolution of MAS/BPF composites were characterized by XRD,XPS,and SEM analyses.The experimental results reveal that the increase of calcine time result in the fewer holes,relatively denser and smoother top layer of MAS/BPF composites and protect the interior from deeper decomposition.The final residues of composites are amorphous carbon and C-O-Si-Al-Mg ceramic.And MAS/BPF composites show excellent mass stability,low shrinkage and self-supporting features after 2 h holding compared with BPF composites without 40wt%of inorganic fillers.

Preparation of Phenolic Resin/Silver Nanocomposites via in-situ Reduction

Resol type phenolic resin/silver nanocomposite was prepared by in-situ reduction method, in which the curing of phenolic resin and the formation of silver nano-particles took place simultaneously. The silver ions were reduced completely to silver nanoparticles, which were dispersed homogeneously in the resin matrix with narrow size distribution.

Synthesis and Properties of Novel Epoxidized Soybean Oil-modified Phenolic Resin /Montmorillonite Nanocomposites

The novel epoxidized soybean oil-modified-phenolic resin/clay nanocomposites（ESO-M-PR/ CN） was prepared. The coupling agent-benzyldimethylphenylammonium chloride [C6H5CH2N^＋（CH3）2C6H5Cl^- , B2MP] was adopted to modify the interface between the organic and inorganic phases. The effect of the nanocomposite structure on its physical and chemical properties was discussed. During the synthesizing process of ESO-M-PR/CN, the phenol hydroxyl was etherified by ESO or ESO epoxy resin prepolymer to provide long ESO epoxy segments. Long ESO epoxy resin chain segments enhanced the crosslink density of ESO-M- PR/CN. The thermal and mechanical properties exhibit a significant improvement. The temperature at which a weight loss of 5% occurs increases from 287.1 ℃ to 402.3 ℃. The flexural strength increases by 25%, while the flexural modulus increases by 39%. Moreover, the properties of resin were enhanced by the effect of the inorganic nanoparticles, while the size of the nanomontmorillonites in the phenolic resin was characterized with a scanning electron microscope. The particle size of inorganic montmorillonites in the modified system is less than 100 nm.

Fluxing Agents on Ceramification of Composites of MgO-Al2O3-SiO2/Boron Phenolic Resin

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al_2O_3-SiO_2/boron phenol formaldehyde resin（MAS/BPF） composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS/BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS/BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS/BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.

Effect of KCI on Growth of Carbon Fibers During Carbonization of Phenolic Resin

Effects of the KCI additions （1%, 3%, 5% and 7% of the phenolic resin mass ） on phase composition and microstructure of the resin carbon and the growth mechanism of carbon fibers were investigated by using commercial liquid phenolic resin as carbon source and micron-scaled KCl us catalyzer, mixing, hexamethylene- tetramine solidification treating, carbon-embedded firing at 1 000 ℃ for 3 h in order to accelerate the graphitization of phenolic resin during carbonization. The results show that the graphitization degree of resin carbon is im- proved by catalysis of KCl, numerous carbon fibers with 30 - 200 nm in diameter and 10 - 20 μm in length and sheet-like carbon in situ grow in resin carbon. The opti- mal addition of KCl is 5% when lots of carbon fibers can be found in resin carbon, and doo2 diffraction peak of graphite appears obviously in the XRD pattern. The growth mechanism of carbon fiber is that the molten KCl at high temperatures absorbs carbonaceous gas from the decomposition of phenolic resin, accelerating the diffu- sion of solid C atoms in liquid KCl ; after the dissolution of C saturates, carbon atoms separate continuously in lo- cal parts to form carbon fibers or flakes ; meanwhile, the concentration gradient formed by local carbon atoms in the melt offers growth drive for the separation of carbon fibers or flakes on KCl surface.

Preparation of Intercalated Clay/Phenolic Resin Nanocomposites under High Pressure

High pressure method was ased for the first time to produce rectorite clay （REC）/phenolic resin （PF） and organic rectorite clay （OREC） /phenolic resin and montmorillonite（ MMT）lphenolic resin （PF） nanocomposites. The structure of the material phase was studied by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, Fourier transform infrared （ FT- IR ） spectroscopy, thermogravimetric analysis （ TGA ）, and atomic force microscopg＂ （AFM）. The experimental results show that intercalated clay/resin nanocomposites could form under normal temperature and high pressure conditions by the intercalation of polymeric molecules rather than interlayer polymerization.

STUDY ON THE OXIDIZED GRAPHITE MATERIAL COATED WITH N-DOPED PHENOLIC RESIN FOR LITHIUM ION BATTERIES

Carbon-coated oxidized graphite has been prepared by a liquid-state deposition method. Oxidized graphite wasprepared by wet chemical oxidation. Oxidation increases the reversible capacity of graphite, but its initial charge anddischarge efficiency was reduced. Phenolic resin was applied to form the disordered carbon layer on the oxidized graphite.The efficiency and reversible charge capacity were obviously increased. The morphology of carbon materials wasinvestigated by SEM.

Studies on Thermodynamic Properties of Adsorption of Theophylline by Phenolic Resin Adsorbents

In the present work,the equilibrium adsorption of theophylline was studied by phenolic resin adsorbents: JDW\|2(made by ourselves) and Duolite S\|761 within a temperature range of 303\_323 K. The experimental results show that the Freundlich adsorption law is applicable to the adsorption of theophylline on the two adsorbents,the exponents \%n\%>1 indicate that they are favorable to the adsorptions;the negative values of all the isosteric adsorption enthalpies for the theophylline indicate the exothermic process of the adsorption,while the range(10\_40 kJ/mol) of their magnitudes manifests the physisorption process;other thermodynamic properties,the free energy changes and the entropy change associated with adsorption have been calculated from the Gibbs adsorption equation and the Gibbs\|Helmholtz equation.

SYNTHESIS OF MELAMINE AND CASHEW NUT SHELL LIQUID MODIFIED PHENOLIC RESIN

Melamine,cashew nut shell liquid modifed phenolic resin is a kind of high temperature-resistance resin used in friction materials.This paper describes the resin formulation,synthesis,charac- teristic indexes,mechanical strenghth, infrared ray spectrum,TG,DTA,and discusses the sythetic way of resin modified result and the influence of catalyst on the reaction speed.

Fabrication and Properties of SiB6-B4C with Phenolic Resin as a Carbon Source

Si-B-C ceramic composites were synthesized using SiB-6,B-4C,and phenolic resin as a carbon source by pressureless sintering in an Ar atmosphere.Then,the Si-B-C ceramic composites were fabricated to determine their potential for applications as high hardness and high temperature composites.The X-ray diffraction patterns of sintered bodies of SiB-6-B-4C with carbonized phenolic resin can be seen that SiB-6 and C changed to B-4C and SiC.In this study,it is obtained that carbonized phenolic resin is good addition material as a reaction material comparing to carbon powder at 1683 K for 1 h by pressureless sintering in an Ar atmosphere.

Simulation on Pyrolysis Products of Thermoset Phenolic Resin with Different Chemical Structure and Experimental Validation

The simulation on pyrolysis products of pure PF resin with different chemical structure was investigated and validated by pyrolysis gas-chromatography mass spectrometry(Py-GC/MS).The simulation of pyrolysis products of phenolic resin with different chemical structure was investigated by AMBER(Assisted Model Building with Energy Refinement)force field.The content of pyrolysis products phenol and cresol decreases with the increase of F/P(formaldehyde/phenol)value.The content of pyrolysis products dimethylphenol and trimethylphenol increases with the enhancement of F/P value.The crosslink density of phenolic mixture can be measured by the content of pyrolysis products dimethylphenol and trimethylphenol.Consequently,the results of simulation were validated by the Py-GC/MS experiment.

Electrospun porous carbon nanofibers derived from bio-based phenolic resins as free-standing electrodes for high-performance supercapacitors

Phenolic resins were employed to prepare electrospun porous carbon nanofibers with a high specific surface area as free-standing electrodes for high-performance supercapacitors.However,the sustainable development of conventional phenolic resin has been challenged by petroleum-based phenol and formaldehyde.Lignin with abundant phenolic hydroxyl groups is the main non-petroleum resource that can provide renewable aromatic compounds.Hence,lignin,phenol,and furfural were used to synthesize bio-based phenolic resins,and the activated carbon nanofibers were obtained by electrospinning and one-step carbonization activation.Fourier transform infrared and differential scanning calorimetry were used to characterize the structural and thermal properties.The results reveal that the apparent activation energy of the curing reaction is 89.21 kJ·mol–1 and the reaction order is 0.78.The activated carbon nanofibers show a uniform diameter,specific surface area up to 1100 m^(2)·g^(-1),and total pore volume of 0.62 cm^(3)·g^(-1).The electrode demonstrates a specific capacitance of 238 F·g^(-1)(0.1 A·g^(-1))and good rate capability.The symmetric supercapacitor yields a high energy density of 26.39 W·h·kg^(-1)at 100 W·kg^(-1)and an excellent capacitance retention of 98%after 10000 cycles.These results confirm that the activated carbon nanofiber from bio-based phenolic resins can be applied as electrode material for high-performance supercapacitors.

Preparation and Characterization of Polyborosiloxanes and Their Blends with Phenolic Resin as Shapeable Ceramic Precursors

Two polyborosiloxanes （PBSis） with char yield up to 74.13% at 800 ℃ were synthesized by the direct polycondensation of boric acid with phenyltrimethoxysilane in diglyme. The PBSis were characterized by gel permeation chromatography, IR spectroscopy as well as ^1H-, ^29Si- and ^11B-NMR. PBSi modified phenol-formaldehyde resins （PBSi/PFs） were prepared at different PBSi/PF mass ratios and were cured at 150 ℃. The PBSi/PFs were characterized by IR spectroscopy, scanning electron microscopy, thermogravimetric analysis and tensile test. The results revealed that the cured PBSi/PFs had sea-island morphology and higher char yield than the common PF. PBSi/PF blend with PBSi/PF mass ratio of 0.4：1 had char yield up to 70.83% at 800 ℃. The PBSi/PFs had tensile strength similar to PF. The ceramization of PBSi/PFs was also studied. The silicon boron oxycarbide （SiBOC） ceramics formed were characterized by IR spectroscopy and elemental analysis. This method provided a valuable way to prepare easily shapeable polymer blends as ceramic precursors.