Phenol-formaldehyde Oligomers Research Articles

Determination of the properties of modified phenol-formaldehyde oligomers and wood panels based on them

Results of studies of basic properties of the phenol-formaldehyde oligomer SFJ-3014 modified with the a furfurol acetone monomer FA are given. Strength tests of wood-based panels made using the modified adhesives have been performed. By means of IR spectroscopy, an increase in the strength of chemical bonds in macromolecules of a cured modified binder has been established. It has been shown that wood-based panels made on the basis of such a binder have improved physicomechanical properties.

Microphase separation in a cross-linked epoxy phenol polymer

The microphase separation on the surface of samples of a cross-liked epoxy phenol (EP) polymer produced by the curing of a composition containing an epoxy diane oligomer (EO) and a phenol formaldehyde oligomer (PO) has been investigated using electron microscopy with decoration by silver chloride. It has been shown that, in the cross-liked EP polymer, there is a quasi-lattice of mixed-type AgCl nanoparticles, which consists of two sublattices. The formation of simple lattices of particles is caused by the microphase separation according to the type of nucleation and growth of fractal clusters of the cross-liked EO; the spinodal decomposition in the binary system; and the formation of interpenetrating polymer networks represented by the superposition of two lattices of particles or two infinite phase clusters (cross-liked EO and PO, respectively).

Chemical Modification of Polyglycidyl Phenol-Formaldehyde Oligomers by Methacrylic Acid

A new oligomer with unsaturated double bonds in the side chains has been synthesized via chemical modification of polyglycidyl phenol-formaldehyde oligomer (PGPFO) by methacrylic acid (MA) using benzyltriethylammonium chloride as a catalyst. The effect of temperature and reaction time on the reaction proceeded between PGPFO and MA has been studied. The effective rate constants and activation energy of the reaction have been calculated. The structure of the synthesized oligomer has been confirmed by chemical and IR-spectroscopic analyses. The cross-linking of epoxy- oligomeric mixtures based on ED-20 epoxy resin, peroxy derivative of epoxy resin, TGM-3 oligoesteracrylate and synthesized oligomer has been examined using polyethylenepolyamine as a hardener.

Оценка физико-механических и реологических свойств древесных плит на основе модифицированных фенолформальдегидных олигомеров

Оценка физико-механических и реологических свойств древесных плит на основе модифицированных фенолформальдегидных олигомеров

High capacity magnetic mesoporous carbon–cobalt composite adsorbents for removal of methylene green from aqueous solutions

Mesoporous carbons containing cobalt nanoparticles are synthesized by tri-or quad-constituent self assembly of Pluronic F127, phenol-formaldehyde oligomer (resol), cobalt acetylacetonate (acac), and optionally tetraethyl orthosilicate (TEOS, optional). Upon pyrolysis in N2 atmosphere, the resol provides sufficient carbon yield to maintain the ordered structure, while decomposition of the Co(acac) yields cobalt nanoparticles. To provide increased surface area, the dispersed silicate from condensation of TEOS can be etched after carbonization to yield micropores, Without silica templated micropores, the surface area decreases as the cobalt content increases, but there is a concurrent increase in the volume-average pore diameter (BHJ) and a dramatic increase in the adsorption capacity of methylene green with the equilibrium adsorption capacity from 2 to 90mg/g with increasing Co content. Moreover, the surface area and pore size of mesoporous composites can be dramatically increased by addition of TEOS and subsequent etching. These composites exhibit extremely high adsorption capacity up to 1151mg/g, which also increases with increases in the Co content. Additionally, the inclusion of cobalt nanoparticles provides magnetic separation from aqueous suspension. The in situ synthesis of the Co nanoparticles yields to a carbon shell that can partially protect the Co from leaching in acidic media; after 96h in 2M HCl, the powders remain magnetic.

Whey protein-based water-resistant and environmentally safe adhesives for plywood

Whey protein is a renewable and environmentally safe biomaterial, a by-product of cheese production. It can be utilized for non-food applications for value-added products. The substances glyoxal (GO), glutaraldehyde (GA), polymeric methylene biphenyl diisocyanate (p-MDI), urea-formaldehyde (UF) resin, and phenol-formaldehyde oligomer (PFO) that contain reactive groups were applied together with whey protein as modifier in order to increase crosslinking density and molecular weight for improving the bond strength and water resistance of whey protein. A water-resistant and environmentally safe whey protein-based wood adhesive for plywood was developed by evaluating the effects of these modifiers on the bond strength, bond durability, and free formaldehyde emission of the resulting plywood panels. Results of FTIR and SEM analyses and bond evaluation indicated that GO, GA, and p-MDI were not suitable to modify whey proteins due to their high reactivity with whey proteins, causing phase separation. UF resin was not a good modifier for whey proteins because of either its poor water-resistance or higher emission of hazardous formaldehyde. Whey protein adhesives modified with PFO had a dry shear bond strength of 1.98 MPa and a 28h-boiling-dry-boiling wet shear strength of 1.73 MPa, which were both much higher than the required values for structural use according to standard JIS K6806-2003, while its formaldehyde emission was 0.067mg/L, much lower than the required value for green plywood according to standard JIS A5908.

Ordered Mesoporous Carbon Composite Films Containing Cobalt Oxide and Vanadia for Electrochemical Applications

Mesoporous carbon composite thin films (<500 nm) containing cobalt and vanadium oxide were synthesized by triconstituent self-assembly using Pluronic F127 as template, phenol-formaldehyde oligomer (resol) as carbonizable precursor, and cobalt (or vanadyl) acetylacetonate (acac) for the metal source. The ordered mesostructure of the composite films was confirmed by both X-ray diffraction (XRD) and transmission electron microscopy (TEM). During pyrolysis at 800 °C to carbonize the film, the d-spacing decreases significantly because of uniaxial contraction; however addition of Co/V content leads to a decrease in the contraction from approximately 68% to 50%, which indicates the Co/V mechanically strengthens the framework. The decrease in contraction also leads to an increase in the average pore size by as much as 60%. Nanoparticles are found to be dispersed within the continuous carbon framework from both high resolution (HR)-TEM and scanning transmission electron microscopy (STEM); small sub-2 nm particles ...

Protective polymer coatings based on phenol-formaldehyde oligomers modified by propargyl bromoethers

In order to enhance the protective effect, phenol-formaldehyde oligomers (PFOs) are modified by propargyl bromoethers. It is found that resulting composites exhibit high heat resistance, hardness, and adhesion strength. The presence of additional reactive functional groups in their composition favors their use as protective coatings. The effects of various factors on the degree of curing of protective coatings based on PFOs modified with propargyl bromoethers are studied. Polymer coatings made of modified PFOs are tested as the protective coatings of metal samples. It is revealed that the acid resistance of samples of steel (St.-3) coated with the polymer composite survives in chlorhydric and acetic acids.

Extraction of niobium with phenol-formaldehyde resol oligomer Yarrezin B from peroxide solutions

Extraction of niobium with phenol-formaldehyde resol oligomer Yarrezin B from peroxide solutions

Investigation of rheological properties of modified phenol-formaldehyde oligomers

Comparative results of determining the rheological properties of modified adhesive compositions based on phenol-formaldehyde oligomer, main wood species, and flax shive are presented. Recommendations on the application of modified glues in the production of composite materials are given.

Extraction of titanium with phenol-formaldehyde resol oligomer Yarresin B from peroxide solutions

Extraction of titanium by nitrogen-containing phenol-formaldehyde oligomer Yarresin B from peroxide sulfate solutions was studied. Molecular dynamic (MD), molecular mechanic (MM), ZINDO/1 semiempirical (single-point calculations; program package HyperChem, Release 7.52, Hypercube Inc.) calculations, and the Cambridge Structure Database (ConQuest 1.8) were used to solve the structure of the extracted complex [Ti(O)2OR(OH)2]2SO4.

Corrosion properties of adhesives

Advantages and disadvantages of the anodic oxidation method, which is widely used for the preparation of metal and alloy surfaces for adhesive bonding, are considered. A new technology is proposed for the preparation of metal surfaces using a combined electrolyte and an organic corrosion inhibitor. The advanced technology permits increasing the moisture resistance of adhesive joints by three to five times. The results of comparative tests of corrosion activity of a large body of adhesives based on modified epoxy and phenol-formaldehyde oligomers, as well as rubbers, are described. Phenol.-rubber adhesives are shown to possess protective properties and demonstrate corrosion activity, thus increasing the durability of adhesive joints.

Modification of Phenol–Formaldehyde Oligomers with Unsaturated Chlorine (Bromine)-Containing Epoxy Compounds

Modification of Phenol–Formaldehyde Oligomers with Unsaturated Chlorine (Bromine)-Containing Epoxy Compounds

Waterproofing Composites Based on Phenol–Formaldehyde Oligomers

Waterproofing Composites Based on Phenol–Formaldehyde Oligomers

Modification of Phenol–Formaldehyde Oligomers with Propargyl Ethers

Modification of Phenol–Formaldehyde Oligomers with Propargyl Ethers

Using phenol–formaldehyde resin as carbon source to synthesize mesoporous carbons of different pore structures

In this research communication, we performed the phenol–formaldehyde (PF) resin as an alternative carbon source and various mesostructured silicas as the nano-templates to conveniently prepare the mesoporous carbons of high surface area (850–1500 m 2 g −1), large pore size (2.0–22.0 nm) and great pore volume (0.65–1.15 cm 3 g −1). It was reasonably supposed that there exist interaction matching between the negative-charged silica surface of the silica template and PF resin. Therefore, the PF oligomers could be homogeneously adsorbed into the nanochannels or cages of the mesoporous silicas via an impregnation process. Because the thermosetting PF resin only requires a simple heat treatment process at 100 °C to form the cross-linked polymeric structure, the replication of the mesostructure of the mesoporous silica template could be readily achieved without adding any polymerization catalysts.

Cluster structure of epoxy-phenolic polymer prepared by curing a mixture of epoxy-4,4?-isopropylidenediphenyl and phenol-formaldehyde oligomers

The kinetics of viscosity variation and the concentration and kinetic modes of precondensation of a mixture of epoxy-4,4′-isopropylidenediphenyl and phenol-formaldehyde oligomers in Cellosolve solutions in the presence of phosphoric acid at 333 K were studied. The cluster structure parameters of the chemical network of epoxy-phenolic polymeric coating on a tin plate, obtained by thermal curing of precondensates of an oligomer mixture, were determined using the silver chloride sputtering method.

Study of the Adsorption of a Phenol–Formaldehyde Oligomer on the Surface of Magnetic Fillers

Study of the Adsorption of a Phenol–Formaldehyde Oligomer on the Surface of Magnetic Fillers

Synthesis and Properties of Bowl‐Shaped Homotriazacalix[3 and 6]arenes and the Acyclic Analogues.

Bowl-shaped chiral homotriazacalixarenes were prepared by the cyclization reactions of chiral triamines with three equimolar amounts of bis(chloromethyl) phenols or bis(chloromethyl) phenol-formaldehyde dimers in moderate yields. The corresponding acyclic phenol-formaldehyde oligomers were also synthesized. The structural analysis of the macrocycles by nmr and circular dichroism spectra imply the existence of chiral transmission from the point chirality of the cysteine bridge to the cyclophane moiety. Their cyclic and acyclic compounds have a π-base cavity large enough to include the ammonium ion.

Hydrodynamic behavior of epoxy and phenol-formaldehyde oligomers in solution during thermal precondensation

The concentration dependences of the relative viscosity of epoxy-4,4'-isopropylidenediphenol (Epikot 1009, E-05) and phenol-formaldehyde (DFFr) resins in Cellosolve solutions in the concentration range c = 5-60%, as well as the kinetics of thermal precondensation of a mixture of E-05 and DPFr resins in solution at molar ratios N1/N2 = 0.6-1.5, were studied by the method of capillary viscometry. The cluster structure of the surface of coatings on the metal sheet formed by cross-linked epoxy-phenol polymer in various kinetic stages of precondensation of the mixture of E-05 and DFFr resins in solution was studied by electron microscopy with gold decoration. The optimal concentrations of resins in solution and the precondensation kinetics of oligomer mixtures essential for formulating the compounds were calculated.