Phenol-formaldehyde Oligomers Research Articles

Molecular-mass distribution of alkylphenolformaldehyde oligomers modified by imidazolines

The molecular weight distribution of monoalkyl(C8–C12)phenolformaldehyde oligomers modified with imidazolines based on sunfl ower or corn oil fatty acids and polyamines – diethylenetriamine, triethylenetetraamine, polyethylene polyamines was determined by gel-chromatography. The influence of the component and quantitative composition on the parameters of the number average and weight average molecular weights, as well as on the polydispersity of oligomers, was studied. Regularities have been revealed and assumptions have been made regarding repeating monoalkyl (C8-C12)phenol-formaldehyde fragments in the composition of oligomeric macromolecules.

SYNTHESIS OF MONOALKYL(C8-C12)PHENOLFORMALDEHYDE OLIGOMERS MODIFIED WITH IMIDAZOLINES AND AMIDAOAMINES BASED ON NATURAL PETROLEUM ACIDS AND POLYAMINES

Monoalkyl(C8-C12)phenol-formaldehyde oligomers modified with imidazolines and amidoamines based on natural petroleum acids and polyamines have been synthesized. Diethylenetriamine, triethylenetetraamine, polyethylenepolyamines were used as amine compounds in obtaining nitrogen-containing modifiers. The component and quantitative composition of monoalkyl(C8-C12)phenol-formaldehyde oligomers modified with imidazolines and amidoamines of various compositions, the conditions for their preparation are given. The significance of the conducted research is substantiated.

THERMOGRAVIMETRIC STUDY OF MONOALKYL(С8-С12)PHENOLFORMALDEHYDE OLIGOMERS MODIFIED WITH IMIDAZOLINES BASED ON FATTY ACIDS OF VEGETABLE OILS AND POLYAMINES

The thermal properties of monoalkyl(C8-C12)phenol-formaldehyde oligomers modified with imidazolines synthesized from fatty acids of vegetable oils and polyamines (diethylenetriamine, triethylenetetraamine, and polyethylenepolyamines) at different molar ratios have been studied. Fatty acids are obtained by saponification of sunflower and corn oils, followed by the interaction of a mixture of their salts with hydrochloric acid. The dependence of thermal characteristics on the composition of oligomers was studied, regularities were revealed in comparison with unmodified analogues. Appropriate conclusions are drawn.

Study of thermal stability of monoalkyl (С8-С12) phenol formaldehydes functionalized with imidazolines based on fatty acids of palm oil and polyamines

The article provides information about thermogravimetric and differential thermal analysis of monoalkyl (C8-C12) phenolformaldehyde oligomers functionalized with imidazolines obtained at different molar ratios of polyethylenepolyamines and their low-boiling fractions – diethylenetriamine, triethylenetetramine with a mixture of fatty acids of palm oil. It was established that thermal stability of monoalkyl (C8-C12) FFO modified by imidazolins is higher than that of an unmodified oligomer. The multi-stage destruction of the synthesized nitrogen-containing oligomers is explained by their complex structure, and the article also describes possible decay processes in individual stages.

Epoxy–diane co-oligomer modified with benzamide

The epoxy-diane oligomer ranks second (the phenol-formaldehyde oligomer ranks first) among the oligomers by volume of production in the world. It is known that the epoxy-diane oligomer is widely used as a binder in the preparation of many target composites. The reason for this is that its indicators can be adjusted during synthesis. On an industrial scale, it is produced under various brands (Ed-16, ED-20, ED-22, etc.) the produced oligomer has both positive sides and many disadvantages. The disadvantages include low temperature resistance and adhesive ability, some presence of free monomers in the system, and so on. In order to eliminate these indicators, the epoxy-diane oligomer was modified with organic compounds of various natures. The modification process was carried out in an alkaline medium by the method of co-polycondensation. Modification during synthesis (chemical modification) is currently characterized by its relevance. It has become clear from the literature studies that the method of chemical modification is of more interest to researchers working in this field than physical modification. This is due to the fact that the performance indicators of composites based on epoxy-diane oligomer chemically modified by co-polycondensation are approximately 1.5-2.0 times higher than the corresponding indicators of composites based on epoxy–diane oligomer obtained by polycondensation.

Investigation of the structure and mechanism of the synthesis reaction of monoalkyl(C<sub>8</sub>-C<sub>12</sub>)phenol formaldehyde oligomers modified by imidazolines based on fatty acids of vegetable oils and polyamines by the IR-spectroscopy method

The structures of novolac monoalkyl(C8–C12)phenolformaldehyde oligomers modified with imidazolines based on fatty acids of sunflower or corn oils and polyamines – diethylenetriamine, triethylenetetraamine, polyethylenepolyamines were investigated by IR-spectroscopy. As a result of the analysis of the initial and final products, a reaction mechanism is proposed. Optical densities of the absorption bands of the main functional fragments were calculated, and the regularities of the changes depending on the qualitative and quantitative composition of the oligomers were studied.

Production of Phenolic Foams Based on Phenol-Formaldehyde Oligomers of Reduced Toxicity and Material Consumption

This article presents the results of studies considering the possibility of obtaining products based on phenol-formaldehyde oligomers of reduced toxicity, material consumption and corrosive activity. This is achieved by removing free phenol and formaldehyde monomers from the foaming composition and by more complete implementation of hydrodynamic processes during foaming of the composition. The article includes the results of studies on finding the ratio of the initial components and its effect on the corrosive activity of finished products. It is also considered the determination of the dependences of the toxicity and material consumption of phenolic foams on the pressure gradient of the foaming composition and the environment. For the research, the FRV-1A resole prepolymer and the VAG-3 foaming-hardening agent were used as raw materials. The content of phenol and formaldehyde monomers was determined by gas chromatography. In this work, the diagram of installation is developed and presented. It consists of a high-pressure machine, a mold, a vacuum pump, a vacuum gauge, air supply and air removal pipes. The results indicate that ensuring the formation of a cellular structure of phenolic foam in the low-pressure zone makes it possible to obtain heat-insulating products based on phenol-formaldehyde oligomers of reduced toxicity, material consumption and corrosive activity.

Thorough investigation of non-volatile substances extractible from inner coatings of metallic cans and their occurrence in the canned vegetables

Since the decline of the use of bisphenol A, the chemistry of the varnishes and coatings which are applied to the inner surfaces of metallic food contact materials is poorly documented. We hypothesised that can coatings are now diverse and bring forth various non-intentionally added substances (NIAS) to be described. Investigating complex components such as NIAS requires demanding non-targeted approaches. We investigated the coatings of 12 vegetable cans from the French market. More than 125 substances were pinpointed, among them 84 oligoester combinations from 8 diols and 4 diacids. Thus, oligoesters were the dominant family. Additives such as epoxidised soybean oil, bisphenol A diglycidyl ether and benzoguanamine derivatives and phenol-formaldehyde oligomers were also identified. A software for exploring databases of theoretical combinations of polyester and phenol-formaldehyde resin components (NIAS-db 1.0) was made available. The stepwise organic synthesis of native and deuterated combinations of neopentyl glycol and isophthalic acid (4 and 8 units, linear and cyclic) enabled a higher confidence level and monitoring in vegetable extracts. Migration of oligoesters averaged 330 µg/kg in the drained vegetables (43–1600 µg/kg). This study sheds light on the need to fulfil a proper risk assessment on this NIAS family (exposure and hazard characterisation).

Birch Wood Surface Characterization after Treatment with Modified Phenol-Formaldehyde Oligomers.

Phenol-formaldehyde (PF) resins with well-established molecular sizes are promising treatment agents for wood bulk protection. However, due to the presence of hydroxyl groups on the periphery, the PF oligomers tend to absorb the water, which can lead to water penetration into the wood. To overcome this drawback different PF pre-polymers have been chemically modified with different long-chain fatty acid chlorides (FAC) via esterification. To obtain the modified PF (M-PF) resins, the PF pre-polymers with average molecular weight (Mw) from 266 to 884 g/mol were esterified with decanoyl, lauroyl, myristoyl, palmitoyl, and stearoyl chloride in pyridine as the reaction medium. Silver birch (Betula pendula) wood specimens (15 × 70 × 150 mm3) were coated with M-PF pre-polymer 5% (w/w) solutions in tetrahydrofuran (THF), and hydrophobic properties of treated birch wood specimens were evaluated using surface contact angle (CA) measurements of water droplets. For all M-PF resin-treated specimens, CA was almost 2–2.5 times higher than for untreated wood (45°) and it remained 80–125° after 60 s. The aging properties of M-PF resin-coated birch wood were analyzed using artificial weathering with ultraviolet (UV) light and combination of both UV and water spray. Results clearly confirm, that the hydrophobic properties of M-PF-treated wood has short-term character and will gradually disappear during long-term application in outdoor conditions.

Prospects for obtaining phenol-formaldehyde oligomers

The article provides an overview of recent studies in the development of new methods for the synthesis and use of phenolformaldehyde oligomers. Prospects for carrying out scientific work in this direction, associated with the availability of raw materials, technological and applied aspects, have been substantiated. The main areas of application of phenolic resins have been identified. Special attention is paid to coatings, adhesives, binders, as well as carbon foams based on them. New methods for the modification of phenol-formaldehyde oligomers are described, as well as new compositions of modifying agents for the purposeful change in the complex of their properties.

Phenol–Formaldehyde Oligomers Modified with Carbon Nanoparticles and Their Use in Adhesives and Prepregs

Phenol–Formaldehyde Oligomers Modified with Carbon Nanoparticles and Their Use in Adhesives and Prepregs

Evaluation of water related properties of birch wood products modified with different molecular weight phenol-formaldehyde oligomers

Abstract This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the dimensional stability of birch solid wood and plywood. Therefore, three different low molecular weight PF resins with average molecular weights (M w ) of 292, 528, and 884 g/mol were synthesized and used for silver birch (Betula pendula) solid wood (20 × 20 × 20 mm3) and veneer (100 × 100 × 1.4 and 300 × 300 × 1.4 mm3) impregnation to produce plywood. The weight percent gain (WPG) and bulking after curing of resin treated wood specimens were determined. The leaching was performed to evaluate the PF resin fixation stability. All tested resins at all concentrations were similarly fixed in wood blocks after the leaching (1.5–2.0% WPG loss). The dimensional stability of birch wood after treatment with all tested PF resins was significantly improved. The anti-swelling efficiency (ASE) of birch wood blocks treated with PF resins after seven water soaking-drying cycles was in the range of 39–53%, 46–65% and 49–65% using 10, 15 and 20% solution concentrations, respectively. Whereas, the ASE of plywood obtained from veneers treated with 10% of PF solution was improved by 6–20%. The equilibrium moisture content (EMC) and volumetric swelling (VS) of PF treated plywood at 98% of relative humidity (RH) decreased significantly. All PF resin treated plywood surfaces were more hydrophobic compared to untreated plywood.

Weathering Stability and Durability of Birch Plywood Modified with Different Molecular Weight Phenol-Formaldehyde Oligomers.

This study investigated the effect of phenol-formaldehyde (PF) resin treatment on the weathering stability and biological durability of birch plywood. Silver birch (Betula pendula) veneers were vacuum-pressure impregnated with four different PF resins with average molecular weights (Mw) of 292 (resin A), 528 (resin B), 703 (resin C), and 884 g/mol (resin D). The aging properties of PF resin modified birch plywood were analyzed using artificial weathering with ultraviolet (UV) light, UV and water spray, and weathering under outdoor conditions. The same combinations of PF-treated plywood specimens were then tested in soil-bed tests to determine their resistance against soft-rot wood decay. It was not possible to compare weathering processes under artificial conditions to processes under outdoor conditions. However, the weathering stability of birch plywood treated with PF resins A, B, and C, scored better than plywood treated with commercial resin D (regardless of solid content concentration [%]). Results from unsterile soil bed tests showed improvements in resistance to soft-rot wood decay compared to untreated plywood and solid wood. Mass loss [%] was lowest for birch plywood specimens treated with resin of highest solid content concentration (resin D, 20%). Provisional durability ratings delivered durability class (DC) ratings of 2–3, considerably improved over untreated solid wood and untreated birch plywood (DC 5).

МАТЕРИАЛЫ НА ОСНОВЕ ФЕНОЛФОРМАЛЬДЕГИДНЫХ ОЛИГОМЕРОВ РЕЗОЛЬНОГО И НОВОЛАЧНОГО ТИПОВ (обзор). Часть 2

Describes compositions based on a mixture of phenol-formaldehyde oligomers of the resole and novolac types, used to create foams, laminated plastics for electrical purposes, friction materials, press compositions, sealing putties, as well as for vulcanization of rubbers. Detailed information on the composition and physicochemical properties of the compositions and their technological characteristics are given. The main advantages of resole-novolac materials are shown: strength, heat resistance, reduced flammability, low moisture absorption, good dielectric properties.

МАТЕРИАЛЫ НА ОСНОВЕ ФЕНОЛФОРМАЛЬДЕГИДНЫХ ОЛИГОМЕРОВ РЕЗОЛЬНОГО И НОВОЛАЧНОГО ТИПОВ (обзор). Часть 1

Currently, compositions based on a mixture of phenol-formaldehyde resins of the resole and novolac types are of considerable interest. In the first part of the review examples of the use of resole-novolac phenol-formaldehyde resins in adhesive compositions, prepregs, fiberglass plastics and refractory masses are given. The advantages of using resole-novolac compositions in comparison with resole and novolac phenol-formaldehyde oligomers by increasing the physical and mechanical characteristics, fire resistance and fireproof properties are shown.

Ways to solve the problem of reducing the toxicity of composite wood materials based on urea-, phenol-formaldehyde oligomers

Composite wood materials in the form of chipboards based on urea-formaldehyde resins (grades KF-MT-15, KF-NFP, etc.) are widely used in furniture production. However, one of the main shortcomings of chipboards is their toxicity associated with the release of a gas harmful to humans – formaldehyde. Its maximum permissible concentration in the air of a residential building should not exceed 0,01 mg per m3 of air. The paper shows one of the solutions to the problem of reducing the toxicity of chipboards

Features of some Polymer Building Materials Behavior at Heating

The problems of reducing combustibility and increasing fire resistance of some polymer building materials are considered. And the toxicity of the gaseous products of their thermal degradation was evaluated both individually and in various combinations with each other. The features of thermal degradation and the loss of mechanical properties under the influence of a flame of polymer building materials were studied. The following samples were used: water pipes based on polyethylene; Tarkett linoleum, Ondex roofing products, Rolvaplast PVC profile panels; structural panels of the company "Polygal"; facing tile based on phenol-formaldehyde oligomers. The processes occurring during pyrolysis and combustion are considered, the results of a study of the combustibility and mechanical properties of polymer building materials based on polyethylene, polyvinyl chloride, polycarbonate, phenol-formaldehyde and epoxy oligomers under the influence of a flame are presented. For the studied building polymer materials, the products of pyrolysis and combustion were studied; their ignition and self-ignition temperatures, and also the flame propagation velocity were measured. The data on the toxicity of the products of their combustion, both individually and under combined action, are summarized. Also, for the studied polymer building materials, the losses of heat resistance, toughness, and flexural strength under the influence of a flame were studied. Thermogravimetric analysis of Rolvaplast PVC panels and Poligal polycarbonate panels allowed us to determine the maximum temperatures and activation energies of the polymer decomposition process. It was concluded that if the material is recognized as non-combustible or slow-burning, it will not always be fire resistant, since its strength and thermal properties can sharply decrease already in the first seconds of flame exposure.

THE RESEARCH OF CONDITIONS FOR THE FORMATION OF PHENOL FORMALDEHYDE RESINS MODIFIED WITH HYDROXYL CONTAING POLYETHER POLYOL

The aim of the study was to study the conditions of copolycondensation of phenol alcohol with hydroxyl-containing polyether polyol in the presence of maleic anhydride chain extender in order to obtain modified thermoset phenolic-formaldehyde oligomers. Investigation of the dependence of the content of free phenol, formaldehyde and methylol groups on time during the synthesis of the modified phenol-formaldehyde resin with the ratios hydroxyl-containing polyether polyol:phenol alcohol 1:60 mol/mol and 1:100 mol/mol. It was revealed that maleic anhydride, present in the reaction medium as a copolycondensation catalyst, also participates in copolycondensation reactions as a chain extender. Moreover, as the molar fraction of phenol alcohol increases in the synthesis, an increase in the amount of maleic anhydride involved as a chain extender and an increase in the molecular weight of the resulting modified phenol-formaldehyde oligomer are observed.

Modified Phenol Formaldehyde Reactive Oligomers

Polymeric heat-insulating materials based on casting phenolic foams have low thermal conductivity, reduced fire hazard, high operating temperatures, low cost of the starting components, and biostability. Due to these properties, they are superior in technical and economic indicators to mineral and other polymeric heat-insulating materials used in the construction industry. Low strength, tendency to smoldering, and high toxicity are significant limiting factors for the wider use of thermal insulation materials based on phenol formaldehyde oligomers. Modification of phenol-formaldehyde oligomers can improve the operational properties of materials and products based on them. One way is to introduce chemically active modified additives into the feedstock. As such compounds, metal chlorides of variable valence (FeCl3) and sodium hexafluorosilicate (Na2[SiF6]) were used in the work. It was established by studies that iron (III) salts of 2.0–2.6 wt.% are most effective in reducing toxicity. The simultaneous introduction of sodium hexafluorosilicate in an amount of 0.5 wt.% Allows to reduce the material consumption of products based on phenol formaldehyde oligomers.

ВЛИЯНИЕ МОДИФИКАТОРОВ НА ВРЕМЯ ОТВЕРЖДЕНИЯ ФЕНОЛОФОРМАЛЬДЕГИДНОГО СВЯЗУЮЩЕГО ДЛЯ ПРЕССОВАНИЯ ФАНЕРЫ ПРИ НИЗКОТЕМПЕРАТУРНОМ РЕЖИМЕ

Volumes of plywood production with increased water resistance for indoor and outdoor use (FSF brand) are increasing in Russia. The demand for it in the country and in the world continues to grow. The phenol-formaldehyde oligomer during the curing process passes through the stages of resol, resitol and resite. Ensuring long-term water resistance of plywood is possible only if the resite stage is reached and the solidified phenol-formaldehyde resin (FFR) reaches non-melting and insoluble state. The problem is that the industrial process of FSF plywood pressing is carried out in the rezitol temperature range. In literature, there are conflicting data on the temperature ranges of the stages of the FSF polycondensation process. The authors have proposed to operate with scientific data on the temperature ranges of FFR curing, confirmed by the results of spectroscopic studies. It is necessary to develop phenol-formaldehyde binder compositions capable of curing to the resite stage at lower pressing temperatures than unmodified FSF to ensure the necessary operational characteristics of FSF plywood. In this study, a number of modifiers have been proposed that potentially reduce the time it takes to press plywood at low temperatures. The gelatinization time of the phenol-formaldehyde binder based on the SFZh-3014 resin (according to 20907-2016 State Standard) and modifying additives (hydrogen peroxide, eight-water zinc sulfate, ammonium alum, anhydrous magnesium chloride, six-water iron chloride, six-water aluminum chloride, aluminum dimethyl sulfate, dimethyl glyoximate, and sulfate, sulfosalicylic two-water acid) have been determined. A study of the gelatinization process in the presence of a large number of modifying additives (more than 1.5%) revealed a significant deterioration in the spreadability of the binder. Therefore, it is recommended to use FFR curing accelerators in the amount not exceeding 1-1.5%.