Phenol-formaldehyde Binder Research Articles

Study of the dielectric properties of decomposing materials during heating

The dielectric properties of materials when heated at ultrahigh frequencies are determined by methods based on the use of waveguide cavity resonators. However, as the sample is in the closed volume during measurements, the dielectric properties of destructive material thus determined can contain errors attributed filling of the resonator volume and depositing products of the sample decomposition on the internal conducting surfaces of the resonator. We present the results of studying the dielectric properties of destructive materials under heating in waveguide resonator cavity using methods that exclude the impact of destruction products on the accuracy of measurement. To reduce the influence of destructive vapors rising from the surface of the sample during the destruction process, additional thin quartz plates, placed on the sample surface were used. In addition, cuvettes with a lid were also used to prevent destruction products from entering the resonator volume. A method for taking into account the effect of plates and cuvettes in calculating the dielectric constant and dielectric loss tangent of a material sample when heated in a cavity resonator is presented. Changes in the dielectric properties of a composite material consisting of quartz fabric impregnated with an aluminochromophosphate binder and fiberglass laminate made of quartz fabric impregnated with a phenol-formaldehyde binder were studied in a temperature range above the onset of the destruction (up to temperatures at which loss of the structural strength of the material is observed). The developed method can be used in studying the thermophysical properties of destructive materials to assess changes in their dielectric characteristics under operation conditions of high-temperature heating.

Antifrictional composites based on a two-component modified phenol-formaldehyde binder

In this paper, new polymer composite materials (PCM) based on a mixture of the resole type phenol-formaldehyde and phthalide-containing phenol-formaldehyde binders, reinforced with polyoxadiazole fiber, were obtained, and their tribological properties were studied. The influence of the content of phthalide-containing phenol-formaldehyde polymer in a two-component mixture of binders on the hardness of the surface layer, tribological and thermofrictional properties of PCM in various units of dry friction on steel has been studied. It is shown that the resulting PCM are superior to PCM based on phenol-formaldehyde or phthalide-containing phenol-formaldehyde binders of the resole type in terms of tribological and thermal friction properties.

CERAMIC-FORMING ORGANOSILICON POLYMER AS A MODIFIER OF HEAT-INSULATING SYNTHETIC MATERIAL

The paper presents the results of obtaining hardened synthetic carbon materials that can be used for technical thermal insulation under conditions of elevated pressures and temperatures. The hardened syntactic carbon material is obtained by mixing hollow carbon microspheres pretreated with a catalyst with vanadium (III) chloride with a phenol-formaldehyde binder with the addition of fine polydimethylsilane forming the composition at low pressure, holding the mold at 150 ?C for 2 hours, followed by heat treatment in an inert medium at 375 ?C and final carbonation in combination with carbidization when the temperature rises at a rate of 100 ?C/h to 900 ?C. The physicomechanical and thermophysical characteristics are studied. Synthetic material can be used for the manufacture of thermal insulation products operating under high temperature conditions.

Plywood for Construction Purposes on a Phenol-Formaldehyde Binder Modified with Hydrogen Peroxide

Reducing the pressing temperature of plywood on the FF binder allows you to reduce its cost, but at the same time, the physical and mechanical characteristics of plywood deteriorate. Modification of the phenol-formaldehyde binder with hydrogen peroxide reduces the curing time of the phenolic binder, the pressing temperature of the FSF plywood, and improves the physical and mechanical properties of the FSF plywood. Regression models have been developed for dependence of the plywood strength during cleavage along the adhesive seam, strength during static bending, and thickness swelling after 24 hours in water on the factors varied in the experiment – the proportion of hydrogen peroxide addition and the pressing temperature. The IR spectra of plywood allow us to estimate the effect of H2O2 on the bonds involved in the structure formation of material. With the addition of hydrogen peroxide, the number of active methylene groups decreases, which indicates an increase in degree curing of modified binder.

Технологические факторы и свойства теплоизоляционных плит из растительных наполнителей

Wood processing soft waste is mainly used in the production of fuel briquettes, irrecoverable (non-recyclable) waste from spinning flax and cotton are incinerated or sent to dump. The development of methods for recycling non-recyclable cellulosic waste through the product manufacturing is relevant, both from the resource conservation perspective, as well as the environmental point of view. The issues of plant waste recycling through the manufacturing of various types of products are widely developed in the Russian and foreign scientific research practice. Researchers deal with the processing of wheat, rice straw, bamboo stalks, and other cellulosic materials. There is a plenty of published information on methods of soft wood waste recycling. However, no research on recycling irrecoverable waste of spinning flax and cotton fibers had been carried out before this paper. We propose to produce thermal insulation boards based on phenol-formaldehyde resol binder using flax and cotton spinning waste and soft wood processing waste. The wet production method used here involves mixing the filler with water, a precipitant solution and a binder. After spinning the material is dried. The paper presents the results of determining the physical and mechanical properties and thermal conductivity coefficient of boards made of plant waste. The research was carried out according to the B-plan of the second order. Adequate regression mathematical models of the dependences of physical and mechanical parameters of the boards on the varying factors of the production process were developed according to the experimental data processing results. Using the developed regression models we built the response surfaces of the composite parameters: the bending strength of the boards, the thickness swelling of the boards after 24 h of exposure in water and the thermal conductivity coefficient. Nomograms of the dependencies of board parameters on the values of varying factors have been developed based on the mathematical models analysis. The nomograms are the basis for the development of practical recommendations for determining the rational values of the parameters of insulation board materials production from irrecoverable waste of spinning flax and cotton and soft wood processing waste.

Фанера и теплоизоляционные плиты на модифицированном фенолоформальдегидном связующем

The lower curing temperature of phenol formaldehyde binder allows reducing the costs of producing cellulose-containing materials, such as FSF plywood and thermal insulation composites made of plant wastes. However, the low-temperature production mode provides an insufficient degree of the phenol formaldehyde binder curing, leading to a decrease in water resistance of material based on the phenol formaldehyde binder. A modifier should be added to the phenol formaldehyde binder to reduce the amount of free hydroxymethylol groups in the cured binder and to form a stronger cross-linked structure in low-temperature curing conditions. Hydrogen peroxide was used as a phenol formaldehyde binder modifier in this research. The research results confirmed the hypothesis about the effect of hydrogen peroxide on the intensification of the structure formation of cellulose-containing materials based on the phenol formaldehyde binder. In conditions of low-temperature curing (120 °C for FSF plywood and 100 °C for thermal insulation composites made of plant wastes) modification of phenol formaldehyde binder with hydrogen peroxide reduced the binder curing time, the pressing time of FSF plywood, improved the physical and mechanical properties of FSF plywood and thermal insulation composites made of cellulose-containing filler (soft wood waste and irrecoverable flax spinning waste). When 1.0 % of hydrogen peroxide is added to the binder, the binder curing time reduces by 43.6 %. The addition of 1.0 % of hydrogen peroxide increased the shear strength of FSF plywood by 4.4 % and the static bending strength of plywood by 4.8 %. Modification of the binder with hydrogen peroxide increased water resistance of FSF plywood: plywood thickness swelling has been reduced by 2 % over 24 h in water. The strength of thermal insulation composites made of cellulose-containing wastes increased by 5.2 % with the addition of 1.0 % of hydrogen peroxide, thickness swelling decreased by 4.9 % over 24 h. The obtained research results allow recommending a modifying additive of hydrogen peroxide to phenol formaldehyde binder in an amount of 1.0 % of resin mass to increase the strength properties of FSF plywood and thermal insulation composites made of plant wastes. For citation: Vakhnina T.N., Fedotov A.A., Susoeva I.V., Rumyantseva V.E. Plywood and Thermal Insulation Boards Based on the Modified Phenol Formaldehyde Binder. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 155–165. DOI: 10.37482/0536-1036-2022-1-155-165

ВЛИЯНИЕ ФАКТОРОВ ПРОЦЕССА ПРОИЗВОДСТВА НА ПОКАЗАТЕЛИ ФАНЕРЫ НА МОДИФИЦИРОВАННОМ ФЕНОЛОФОРМАЛЬДЕГИДНОМ СВЯЗУЮЩЕМ

To reduce production costs, FSF plywood is produced by pressing at a reduced temperature. However, at the same time, the resite stage is not provided for the phenol-formaldehyde binder, which results in a decrease in the physical and mechanical properties of plywood. In the world and Russian practice of scientific work, this problem is solved in various ways: by modifying the binder at the stage of its synthesis, by preliminary surface treatment of veneer, by modifying phenol-formaldehyde binder at the stage of synthesis or “on site”. To develop a rational combination of the values of the production process factors, which makes it possible to form a more durable structure of plywood during low-temperature pressing, a modification of the binder with the addition of dimethylglyoxime was used. An experiment was carried out on the B-plan of the 2nd order. The following varied: proportion of dimethylglyoxime addition (from 0.5 to 1.5% of the binder mass), pressing temperature (from 110 to 130 ºС), pressing time (from 4 to 5 min). Regression models have been developed for the ultimate strength of plywood when chipping along the adhesive layer, ultimate strength in static bending, and thickness swelling of plywood after 24 hours in water. It was found that with an increase in the proportion of dimethylglyoxime additive to 1.5%, the shear strength of plywood increases by 25%, the static bending strength by 30%, and thickness swelling by 10%. This allows us to conclude about the deepening of the process of structure formation of FSF plywood when pressed on a modified binder. Recommendations for the rational combination of the values of the factors of the production process of FSF plywood have been developed

Water resistance of thermal insulation composites with cellulose-containing filler

One of the urgent tasks is the development of new thermal insulation materials to improve the energy efficiency of construction. In this work, new composites were obtained based on previously unused cellulose-containing waste. The theoretical and experimental substantiation of the possibility of increasing the water resistance of the heat-insulating composite has scientific significance. The features of the supramolecular structure of cellulose are analyzed. As a result of studies of the process of structure formation of a new heat-insulating material, it has been established that to ensure stable heat-insulating properties of composites from cellulose-containing waste, it is advisable to use a phenol-formaldehyde binder, water glass, or alumochromophosphate. The developed composite has a swelling 2.7 ... 3 times less, and water absorption 2.2 ... 2.4 times less than mineral wool slabs. The coefficient of thermal conductivity of the new composite material, depending on the type of cellulose-containing filler, ranges from 0.076 to 0.092 W/m∙K, which makes it possible to recommend it for use in thermal protection of buildings.

ПОВЫШЕНИЕ ПРОЧНОСТНЫХ ПОКАЗАТЕЛЕЙ ФАНЕРЫ ФСФ ПУТЕМ ИСПОЛЬЗОВАНИЯ МОДИФИЦИРУЮЩИХ ДОБАВОК К СВЯЗУЮЩЕМУ

Improving the production process of FSF waterproof plywood has been relevant since the beginning of its pro-duction. Only the criteria for improving the quality of plywood products are changing. At the present stage, the costs of improving the quality of plywood cannot be compensated by an increase in prices. Reduction in production costs is required. A rational way to improve operational properties is to reduce pressing temperature and introduce modifying additives that increase adhesive and cohesive strength of phenol-formaldehyde binder. The problem is that when press-ing temperature is reduced to 150 °C or lower, phenol-formaldehyde binder does not reach the resite stage. It negatively affects the strength and water resistance of FSF plywood. It was decided to use modifying additives in the adhesive composition to bind free methylol groups of the oligomer and increase the number of active sites in the curable phenolic binder network. The strength properties of FSF plywood with the use of nine modifying additives have been investigated. The consumption of modifiers varied in the range of 0.25-1.5% in increments of 0.25%. Pressing was carried out at a temperature of 120 °С. An improvement in the tensile strength of plywood when shearing on the adhesive layer was found to be 5-15% (in comparison with control samples without the addition of a modifier) when aqueous solutions of hexavalent aluminum chloride, anhydrous magnesium chloride, eight-zinc zinc sulfate, sulfosalicylic acid, dimethylglyoxime with a different proportion of additives were used as modifying additives to phenol-formaldehyde binder. Tensile strength under static bending of plywood is also increased when using modifiers with different proportion of additives

Efficiency of homely synthesized magnetite: carbon composite anode toward decolorization of reactive textile dyes

Electrochemical degradation procedure for the removal of organic dye Reactive Blue 52 using nano-magnetite-doped carbonaceous electrodes was proposed. The electrode was prepared by calcination of graphite grains mixed with phenol–formaldehyde binder modified with iron nitrate. The morphology and phase composition of the electrodes were investigated using scanning electron microscopy and powder X-ray diffraction. Electrochemical degradation was done in Nafion membrane-divided cell where anodic part was filled with color solution and cathodic with supporting electrolyte. Parameters affecting on decolorization rate were investigated. A high increase in the removal efficiency, under optimized parameters, was noticed using carbon electrodes containing 1 mass% of magnetite in the presence of 3 mM hydrogen peroxide and 7 mass% of magnetite in the presence of 10 mM hydrogen peroxide. Almost 100% decolorization was achieved during 30 min with 62–77% of the mineralization. Based on these results, it can be concluded that this approach offered green, cheap and efficient degradation of reactive dyes and could be used as promising candidate for wastewater processing in the textile industry.

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%.

Experimental study of the correlation between the elastic modulus of polymer composite materials and the velocity of ultrasonic waves

This article presents the results of an experimental study of the relationship of acoustic parameters (propagation velocity) of ultrasonic waves with elastic characteristics (elastic modulus) of polymer composite materials. Significant regression dependences of the correlation between the velocity of ultrasonic won and the modulus of elasticity of a composite material based on fiberglass with an epoxy and phenol-formaldehyde binder have been constructed.

ОЦЕНКА ВОЗДЕЙСТВИЙ КЛИМАТИЧЕСКИХ ФАКТОРОВ НА ЭКСПЛУАТАЦИОННЫЕ СВОЙСТВА СТЕКЛОПЛАСТИКА МАРКИ ВПС-42П/Т-64

The study of the operational properties of fiberglass, developed for use in the air conditioning system of aircraft, after exposure to accelerated climatic factors. The results of studies of the properties of fiberglass based on phenol-formaldehyde binder grade VSF-16M after exposure to thermal and heat-moisture aging, the influence of aggressive media, as well as mycological tests are considered. The microhardness of a polymer matrix in plastic is investigated depending on the influence of operating factors. The assessment of the properties of fiberglass for compliance with the norms of AP-25 (p. 831 «Ventilation» – the content of toxic impurities in the air).

A Review of the Compositions, Processing, Materials and Properties of Brake Pad Production

This is a review and overview of the trending researches in automobile brake pad production processes, formulations, materials, and properties. Most of the works attempt mainly on replacing asbestos found to be carcinogenic with base materials with other ingredients in various formulations and particle sizes. Though most of the replacements are non-hazardous with properties such mechanical and tribological cauterizations comparing well with the traditional asbestos based brake pad. The overview of these trends suggests the need to replace not only the asbestos but also the commonly used epoxy resins or phenolic resins or phenol formaldehyde binders that has been found to corrode outside plates of brake assembly. These reviews has thrust a new research direction of replacing the asbestos and inorganic resins with agro based materials of Cashew Nut Shell and Plant Gum binder respectively to obtain a substantially green based brake pads that are non-injurious to human health and does not corrode any parts of the brake pads assembly.

A study into the scale effect on the strength properties of polymer composite materials

Polymer composite materials (PCM) are used extensively and are viewed as candidates for application in various industries, including nuclear power. Despite a variety of methods and procedures employed to investigate the mechanical characteristics of PCMs, the use of the laboratory sample mechanical test results to design and model large-sized structures is not always fully correct and reasonable. In particular, one of the problems is concerned with taking into account the scale parameter effects on the PCM strength and elastic characteristics immediately in the product. The purpose of the study is to investigate the scale effects on the mechanical characteristics of glass reinforced plastics using phenolformaldehyde and silicon-organic binders and a fabric quartz filler. Samples of four different standard sizes under GOST 25604-82 and GOST 4648-2014 were tested for three-point bending using an LFM-100 test machine to estimate the scale effect. The thicknesses of the model samples were chosen with regard for the wall thicknesses of full-scale products under development or manufactured commercially and the test machine features, and varied in the limits of 1.6 to 7.5 mm. The tests showed that strength decreased as the sample thickness was increased to 3 mm and more both at room and elevated (200 to 500 °C) temperatures, which can be described by an exponential function based on the Weibull statistical model. The values of the Weibull modulus that characterizes the extent of the scale effect on the strength of the tested materials were 4.6 to 6.7. The average bend strength in the sample thickness range of 3 mm and less does not vary notably or tends to increase slightly as the thickness is increased. This fact makes it possible to conclude that estimation of allowable stresses in a thin-wall product requires the use of test results for samples with a thickness that is equal to the product wall thickness since standard samples may yield overestimated allowable stress values and lead, accordingly, to incorrect calculations of the strength factor. The results obtained shall be taken into account when defining the allowable levels of operation for full-scale products and structures of polymer composites based on the laboratory sample strength data as well as when estimating their robustness as a characteristic of the product’s fail-safe operation.

A study into the scale effect on the strength properties of polymer composite materials

Polymer composite materials (PCM) are used extensively and are viewed as candidates for application in various industries, including nuclear power. Despite a variety of methods and procedures employed to investigate the mechanical characteristics of PCMs, the use of the laboratory sample mechanical test results to design and model large-sized structures is not always fully correct and reasonable. In particular, one of the problems is concerned with taking into account the scale parameter effects on the PCM strength and elastic characteristics immediately in the product. The purpose of the study is to investigate the scale effects on the mechanical characteristics of glass reinforced plastics using phenolformaldehyde and silicon-organic binders and a fabric quartz filler. Samples of four different standard sizes under GOST 25604-82 and GOST 4648-2014 were tested for three-point bending using an LFM-100 test machine to estimate the scale effect. The thicknesses of the model samples were chosen with regard for the wall thicknesses of full-scale products under development or manufactured commercially and the test machine features, and varied in the limits of 1.6 to 7.5 mm. The tests showed that strength decreased as the sample thickness was increased to 3 mm and more both at room and elevated (200 to 500 °C) temperatures, which can be described by an exponential function based on the Weibull statistical model. The values of the Weibull modulus that characterizes the extent of the scale effect on the strength of the tested materials were 4.6 to 6.7. The average bend strength in the sample thickness range of 3 mm and less does not vary notably or tends to increase slightly as the thickness is increased. This fact makes it possible to conclude that estimation of allowable stresses in a thin-wall product requires the use of test results for samples with a thickness that is equal to the product wall thickness since standard samples may yield overestimated allowable stress values and lead, accordingly, to incorrect calculations of the strength factor. The results obtained shall be taken into account when defining the allowable levels of operation for full-scale products and structures of polymer composites based on the laboratory sample strength data as well as when estimating their robustness as a characteristic of the product’s fail-safe operation.

The decomposition process and kinetic analysis of commercial binder based on phenol-formaldehyde resin, using in metal casting

Kinetic characterization of the degradation of resins is important for understanding structural changes, which occur during the different phase of degradation, and study of that can help predict and improve the industrial performance of the resin. Thermal decomposition behavior of commercial binder based on phenol–formaldehyde (PF) resin, using in metal casting were studied using a conventional dynamic thermogravimetric analysis TGA/DTG at different heating rates ß: 5, 10, 20 and 30 °C/min under inert atmosphere. The kinetic parameters of thermal degradation of PF binder were investigated using model-free methods: integral Kissinger-Akahira-Sunose (KAS) and differential method after Friedman as well as the model-based method. The initial kinetic parameters values for nonlinear model-fitting were taken from the model-free evaluations. Activation energy is a kinetic parameter that reflects the sensitivity of the resin to temperature. The thermal stability of samples was estimated by measuring the degradation temperature, which was calculated according to the maximum reaction rate criteria.

Preparation and Characterization of Phenol Formaldehyde Bonded Nd–Fe–B Magnets With High Strength and Heat Resistance

The phenol formaldehyde (PF), a kind of heat-resistant binder, was used to prepare bonded Nd–Fe–B magnets via mold pressing. The magnetic properties, compressive strength, and microstructure of the magnets were systematically investigated. The magnetic measurements show that PF binder endows Nd–Fe–B magnets excellent magnetic properties. Moreover, the magnets can keep the original shape and exhibit usable magnetic properties at 200 °C. With increasing binder content, the compressive strength of the magnets reach 253.6 MPa with 4 wt.% PF binder, which is 14 times higher than that of epoxy resin bonded Nd–Fe–B magnets. In addition, the reason of high compressive strength was investigated. The main chain of PF binder molecule contains rigid structure like benzene rings, which can form hard cross-linking network structure in the gaps of magnetic powders making the bonded magnets with high strength. Further fracture surface morphology observation and energy dispersive X-ray analysis reveal that liquid PF binder can permeate into gaps between the magnetic powders during the process of warm-molding and exert excellent bonding effect. Two mechanisms of action can endow PF/Nd–Fe–B magnets excellent mechanical strength and heat resistance.

Production and investigation of physical-mechanical properties of syntactic carbon foams

The production technology of syntactic carbon foams based on the phenol-formaldehyde binders and microspheres was developed. The influence of the composition and regime technological parameters on the change of the physical-mechanical properties of foams was investigated.

Soy-substituted liquid phenol formaldehyde binders for flakeboard

The degree to which liquid phenol formaldehyde resin for flakeboard applications can be replaced by soy flour was studied through a design of experiment approach. Up to ten percent substitution could be achieved while substantially maintaining board properties. Higher levels of substitution increased the viscosity of the resin droplet, which reduced resin spread and various strength properties. The loss of strength was most apparent for dense boards where the spreading limitation reduced the relative bonded area.