Polyvinyl Acetate Dispersion Research Articles

DEVELOPMENT OF DRY BUILDING MIXTURES BASED ON REDISPERSIBLE POWDER FOR REGULATING THE PROPERTIES OF PLASTER MIXTURES

The relevance of the work. The results is theoretically substantiated and experimentally confirmed the possibility of obtaining a dry additive-retarder of gypsum setting based on lime and polyvinyl acetate dispersions due to the formation of polyvinyl alcohol and salts of calcium acetate in the result of alkaline hydrolysis of polyvinyl acetate dispersion (PVAD) with the slaked lime in hydrated lime. The results of the work implemented in the production of dry gypsum mixes. Purpose. The development of dry building mixes based on gypsum and time increase of time of their conformance through adding of complex additives on the basis of burnt lime and polyvinyl acetate dispersions [PVAD]. Methodology. The study used standard research techniques to determine physical and mechanical properties of gypsum binders and quality of complex additives according to ДСТУ Б В.2.7-82:2010, ДСТУ Б В.2.7-23-95, ДСТУ Б В.2.7-171:2008. Study of phase composition of materials, micro – and macrostructure was carried out by x-ray diffraction, electron and light microscopy. The results. The influence of the main components of the additive (polyvinyl acetate dispersion and lime) on the properties of hemihydrate gypsum is investigated. The chemistry of the interaction of components of the complex additive, according to which the result of alkaline hydrolysis of polyvinyl acetate is formed: polyvinyl alcohol, a feature of its molecules structure is the presence of hydrophilic OH−groups and the hydrophobic component − a hydrocarbon radical. The hydrophilic part of the molecule being ion adsorbed on the surface of the particles of the binder, forms a monomolecular layer that is oriented with the hydrophobic part of the gypsum particles. It is also possible the formation of calcium acetate Ca(СН3СОО)2, which increases the concentration of calcium ions in solution. The combined effect of hydrolysis products significantly reduce the solubility of hemihydrate, the rate of formation of crystallization centers, due to the slowing effect of these supplements.

Interactions of polyvinyl acetate dispersions with nanostructured superhydrophilic and superhydrophobic Ti6Al4V alloy surfaces

Interactions of polyvinyl acetate dispersions with nanostructured superhydrophilic and superhydrophobic Ti6Al4V alloy surfaces

Исследование прочности клеевого соединения при облицовывании щитовых деталей мебели каменным шпоном

Stone veneer has been known for a long time. But mostly it has been used as a finishing material, which is widely
 applied in decorating the outer surfaces of buildings and facilities. Stone veneer is a thin cut of natural stone - slate, which
 is applied to fiberglass or textiles. The thickness of the veneer is in the range of 2-3 mm. Stone veneer is available in the
 form of rolls or tiles. Due to its flexibility, it can be used to refine surfaces that have angles and small radius of curvature.
 The flexibility of stone veneer is a unique property, since natural stone is not flexible. In today’s world stone veneer is
 trying to find new fields of application. This material is used not only in interior and exterior designs, but also as a
 decorative coating of furniture panels. In this work we have established the possibility of wood board materials facing by
 stone veneer using standard technologies and the most common adhesives used in our country, such as urea-formaldehyde
 resin and polyvinyl acetate dispersion.

A Study of the Structure and Thermodynamic Properties of Polyvinyl Acetate Dispersion after Microwave Electromagnetic Treatment

A Study of the Structure and Thermodynamic Properties of Polyvinyl Acetate Dispersion after Microwave Electromagnetic Treatment

Prospects for Application of Guanidine-Containing Organomineral Complexes as Biocidal Functional Additives for Waterborne Polymer Materials

The possibility of using organomineral complexes of polyhexamethylene guanidine hydrochloride as a functional additive for a waterborne paint based on polyvinyl acetate has been investigated. Organomineral complexes containing 20 and 30 wt % guanidine polymer have been obtained, with intercalation of polyguanidine chains into the interlayer space of montmorillonite being observed. It has been revealed that the stability of the polymer film to water is retained when organomineral complexes are introduced into a polyvinyl acetate dispersion, whereas the water resistance of the film sharply decreases when free polyguanidine is added. There was no significant influence of organomineral complexes on the rheological characteristics of the dispersion and its sedimentation stability. Testing of waterborne paints with various additives has shown that introduction of organomineral complexes into the material prevents the coating from fouling by biofilms of gram-positive bacteria Staphylococcus aureus and Rhodococcus erythropolis, with the hardness, water resistance, and water-vapor transmission of the coatings being retained at a satisfactory level.

Advanced Particle Size Analysis in High-Solid-Content Polymer Dispersions Using Photon Density Wave Spectroscopy.

High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12-55% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (Χ2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques.

Ultraviolet light and natural weathering vs. the compression strength of laminated wood

Effects of protective measures were evaluated relative to the compression strength in the direction parallel to the grain of laminated veneer wood (LVL). For this purpose, laminated panels were prepared from Scots pine, Oriental beech, Castanea sativa, and sessile oak wood veneer by gluing them with Desmodur vinyl trie ketonol acetate (D-VTKA), polyvinyl-acetate (PVAc) dispersion D4 adhesive, resorcinol formaldehyde (RF), and melamine formaldehyde (MF). The samples were impregnated with a mixture of wax, linseed oil, and coated with a synthetic-based translucent varnish. The control samples (without the treatment described above), impregnated samples, and varnished samples were kept in the external environment for 1 y and in an ultraviolet (UV) environment for 240 h. The samples were tested to determine the air-dried density, retention amount, and compression strength. The results indicated that, in terms of outdoor conditions, the varnished proceeding provided better protection compared to the impregnated proceeding. The best result for compression strength was obtained on the Oriental beech samples with RF and MF glues. The ratio of the UV environment to represent the external environment was 89%.

Formation of the structure and properties of highly filled polymer composite materials with a deformable disperse filler

The paper discusses the main patterns of structure formation and the production of highly filled polymer composite materials based on a deformable particulate filler from rice straw (agricultural waste) and a dispersion of polyvinyl acetate (PVA) in water. t has been established that when using a deformable filler of rice straw powder, it is possible to obtain under high pressure (up to ~230 MPa) pressing DFPCM with the highly-filled type of structure and the content of dispersed filler up to ~90% by volume. Such PCM has a sufficiently high level of physical and mechanical characteristics - compressive strength ~104 MPa and elastic modulus ~ 3.0 GPa, which opens up opportunities for its wide application and production of products for various purposes from "green chemistry" materials.

Комплексные полимерные препараты для защиты семян зерновых культур сельскохозяйственных растений

Pre-sowing treatment of seeds of cultivated plants with agrochemicals can significantly reduce crop losses. A promising technology for increasing the yield of spring crops in arid zones characterized by moisture deficiency in the summer is winter sowing. However, this method carries the risk of large losses as a result of premature germination of grain in the event of prolonged positive temperatures in the fall or severe thaws. Special grain processing chemicals can prevent such losses. Complex polymer preparations have been developed to protect grain seeds from premature germination and damage by phytopathogens. It has been shown that compositions based on polyvinyl acetate dispersions and polyacrylamide most effectively prevent premature germination of barley grains. At the same time, treatment with a copolymer of acrylamide and acrylate significantly reduced plant germination. It has been shown that when barley grains are treated with compositions based on polysaccharides with a fungicidal preparation, fungal infection is completely absent, and there is no significant inhibition of seed germination. This composition for treatment against fungal spoilage of grain and seedlings seems promising for practical use.

Effect of Various Binders on the Properties of Microalgae-Enriched Urea Granules.

As the human population grows and the demand for food grows with it, the recycling, or containment of materials is important for resource consumption. Nitrogen is one of the main plant nutrients, most commonly used as the chemical substance urea. Because urea is very soluble and at a relatively low temperature (50-60 °C) it hydrolyses easily (releases N2 and CO2) in soil solutions; this is why very large amounts of nitrogen are lost and greenhouse gases are released and this causes serious environmental problems. Therefore, the aim of this study was to create microalgae-enriched nitrogen fertilizers with different binders that inhibit nitrogen leaching from the soil. Binders such as water (W), polyvinyl acetate dispersion (PVAD), molasses (M), potato starch (S), and carboxymethyl cellulose (CMC) were used in this study and their influence on leaching was analysed. Granular fertilizers were produced in a drum granulator and dryer under equal conditions: granulation time was 7 min, granulation took place at a temperature of 50-60 °C, at a drum rotation speed of 26 rpm, with a 5° inclination angle of the drum. The results show that the highest quantity of the marketable fraction was 43.01 (±3.068%) and it was obtained using urea, with 10% (w/w) microalgae additive, and 11.4% (w/w) of 5% concentration molasses solution. The granules of the fertilizer marketable fraction are similar in size because the size guide number (SGN) of the granules vary in a narrow range and fall within the interval of 287 to 304; this means that the average particle size is ~3 mm. When different binders were used, the average static crushing strength of the granulated fertilizers was lower (approximately 6-12 MPa) than using water alone (approximately 12-16 MPa), but the lower values still fell into the required range. Additives of PVAD solutions and molasses solutions have been found to retain nitrogen in sand. The method of one-way analysis of variance (ANOVA) was used to evaluate the results.

Determination of inline-particle sizes by turbidity measurement in high solid content emulsion polymerisations

Particle size determination in optically dense systems requires costly techniques or dilution of collected samples. Against this background, turbidimetry was investigated as a potentially robust as well as inexpensive alternative. Emulsion copolymerisations of vinyl acetate and VeoVa10® with solid contents up to 48 wt% were examined time resolved with respect to mean particle size at different temperatures, solid contents and with different co-monomer ratios and emulsifier concentrations. The mean hydrodynamic diameters were validated by dynamic light scattering (DLS). Precise number mean hydrodynamic diameters in the range from 100 to 250 nm were obtained in-line for polyvinyl acetate dispersions with deviations in particle sizes below ± 5%. In addition, the turbidity values were recorded by means of a nephelometry process probe and thus a robust, system-related calibration was created, which was subsequently able to reliably track the number mean hydrodynamic diameter inline time-resolved.

Importance of Dynamic Mechanical Analysis to Predict Performance of the Polyvinyl Acetate Wood Adhesives in Summer Season

Conventionally available Polyvinyl acetate (PVAc) wood glues are polyvinyl alcohol (PVA) stabilized, with drawbacks like poor strength at high humidity, poor strength at high temperature and workability at low-temperature. PVAc is non-resistant to high humidity, and if such adhesive bonds are exploited in a highly humid environment, its strength substantially decreases. Sufficiently water-resistant adhesive bonds are achieved by modifying PVAc dispersion with special chemicals like acrylic acid (AA) and N-methylol acrylamide (NMA) as a co-monomer, Silanes, and ethylene modified PVA. The Lewis acids like aluminium chloride and aluminium nitrate are used as cross-linkers. So PVAc adhesives are classified as reactive and non-reactive glue. Application of non-reactive D1 (as per EN 204-205) and reactive D2 and D3 (as per EN 204-205) adhesives for bonding laminate on plywood is a regular practice in the Indian market. In summer time, Crack formation was seen in laminate bonded with reactive D2 and D3 adhesives in regions where the room temperature was above 45°C. However, if the same laminate substrates were bonded with non-reactive D1, no cracks were seen. To analyse the above phenomenon, we have done Dynamic mechanical analysis of non-reactive D1, reactive D2 and D3 adhesive.

State of Research and Trends in the Development of Polyvinyl Acetate-Based Wood Adhesive

Synthetic wood adhesives, consisting of urea-formaldehyde resins (UF), phenol-formaldehyde resins (PF), melamine-formaldehyde resins (MF), and polyurethane resins, are widely used. For UF and MF, most investigations are concerned with reducing free formaldehyde content; for PF, most studies focused on finding new alternative chemicals to replace phenol. These adhesives come under the Carcinogenic, Mutagenic, and Reprotoxic chemicals (CMR) category. Due to global energy issues and dependency on petroleum sources, the focus has shifted to look for alternative and renewable raw material sources for wood adhesives. Conventionally available wood adhesives are polyvinyl alcohol (PVA) stabilized, with drawbacks like poor water resistance, poor heat resistance, low-temperature workability, and it’s based on petroleum resources. Polyvinyl acetate (PVAc) is non-resistant to moisture polymer, and if such adhesive joints are exploited in a moist environment, its strength substantially decreases. Sufficiently moisture-resistant adhesive joints are obtained by modifying PVAc dispersion with special compounds like reactive comonomer, Silanes, and modified PVA. To improve the workability at low temperature, Vinyl acetate (VAc) is copolymerized with specific comonomers like butyl acetate without affecting the performance properties. Here, we aim to present an overview of the research trend of PVAc-based adhesives in the wood industry. The review summarizes the current state of research PVAc-based adhesives.

Study of the influence of modifier concentrations on the technological and physico-mechanical properties of doped packing materials for complete removable dentures manufacturing

Successful dental rehabilitation of a patient with complete removable dentures depends not only on a number of features of the selected design and clinical conditions of the patient's prosthetic area. It depends also on the technology of developing materials used for its manufacture. The purpose of our study was to study the influence of the number of modifiers on technological and physical -mechanical properties of doped packing materials in the manufacture of removable structures of dental prostheses according to the improved method. We performed orthopedic treatment of 45 patients aged 50 to 75 years (average age 59.5±3.2) with complete removable dentures for the upper and lower jaws. We determined the values of the concentrations most favorable to the addition of modifiers in the researched doped packaging material, the introduction of which into the technological process makes it possible to have better indicators of physical and mechanical properties, namely: hydrophilic ratio, total working time, structuring time, relative expansion during structuring, strength compression and roughness index of gypsum samples. If the structuring time of the standard gypsum mixture solution according to ISO-6873 is (4.0±0.2) minutes, then the investigated compositions "Base Stone", "Gypsum highness type 10" and "ORTHOGYPS" with the addition of modified samples of organosilicon emulsion, butadiene styrene latex and polyvinyl acetate dispersion when the minimum dose of modifier concentrations, the average value of which was 0.08–0.10%, was introduced, this time was extended by an average of 2–2.5 times. It was determined that the developed modified components of the alloyed packing material, in turn, provided acceptable accuracy of the base of the removable denture, which corresponded to the working model due to the improvement of the physical and mechanical properties of the packing material. Keywords: modifier compound, complete acrylic removable constructions, gypsum mixture, prosthetic dental rehabilitation.

Effect of the Reinforced Plastic Clamp Fitting on the Bending Strength of the Spruce T-Type Loose Tenon Joints

This article presents the bending strength and flexural properties of the glued T-type spruce loose tenon construction joints with and without reinforced plastic clamp fitting. Construction joints are designed according to Eurocode 5. The samples are made from European spruce (Picea abies Karst.) C24 class construction material with relative wood moisture 18% and relative wood density 410 kg/m3. Samples are assembled with water/high temperature resistant polyurethane adhesive and polyvinyl acetate dispersion adhesive. The total number of samples is 48. The sample width is 95mm and thickness is 45mm. Samples were subjected to moisture, weight controls and 48h stored in the climate chamber before practical bending load test. T-type loose tenon joint construction samples with reinforced plastic clamp fittings glued with polyurethane adhesive under bending load are 2.6% stronger and 13.8% less flexural then without reinforced plastic clamp fittings. T-type loose tenon joint construction samples with reinforced plastic clamp fittings glued with polyvinyl acetate dispersion adhesive under bending load are 9.7% weaker and 20% less flexural then without reinforced plastic clamp fittings. The accuracy of the developed bending strength, deformability and elasticity modulus of the examined construction joints was verified positively by experimental studies.

Technology of Production of Binder Modifying Nanoadditives

The article deals with the issue concerning production of a dry nanoadditive. In order to achieve this goal, an aqueous solution of polyvinyl acetate dispersion (PVAD) and nanotubes, or lime slaking nanoparticles is used. As a result of the hydration process heat is released, the polyvinyl acetate emulsion forms particles with nanotubes in their composition. During the study performed an optimal ratio of all components was established: quicklime + PVAD-CNT – 71-73% and 0.01-0.018 CNT; “Megalith” – 21-25%; ammonium salt – 4-6%, as well as the optimal amount of the complex additive, which is in the range of 1-1.5% by weight of calcium sulfate hemihydrate. Later on the resulting nanoadditive can be used to modify binders or other materials

Designing the Composition of a Cement-Based 3D Construction Printing Material

The physical and technological properties of the 3D construction printing material are formulated. It is shown that the composition should have unique rheological characteristics, controlled setting time, high adhesion, and fast strength. It is determined that a similar material with the required properties can be obtained by creating a composite material based on two active substances: a cementing material and a polymer binder, on one hand, and modification of the particles surface with a superplasticizer, on the other hand. The regularities of the influence of organic components (polymer binder and oligomeric superplasticizer) on the cement matrix are obtained. The mortar mobility, setting time, strength characteristics, and microstructure of the polymer–cement mortar are investigated. A patented composition of the composite material is developed for the innovative construction industry based on Portland cement and polyvinyl acetate dispersion. By modifying the phase boundary of the colloidal system, the proposed composite has the required plastic strength, high setting rate, high fast strength, crack resistance, and a number of other properties necessary for 3D printing of large-sized products and off-formwork structures.

Research of changes of strength indicators of semi-rigid covers glued by modified adhesive compositions

The object of research is the processes for producing modified adhesive compositions based on PVA (polyvinyl acetate) dispersions for use in technological processes for the manufacture of semi-rigid book and magazine covers. The conducted experimental studies are based on the application of a comparative method for determining the tensile strength of glued, without bias, samples of binding materials using modified adhesive compositions and identical compositions without modification. The main assumption of the study is that the use of polymer thickeners and emulsifiers compatible with latex PVA, which are actively used in the technological processes of the paper and printing industries, contribute to the formation of additional strength of semi-rigid covers. This can be achieved without analysis and the selection of possible components, taking into account the mechanical properties that arise after the use of such modifiers that substantially depend on the adhesive strength between the material of the outer part of the cover and the adhesive binder. It is proposed for an experimental study of the use of substances with high adhesive properties to thick coated papers and thin binding boards, from which semi-rigid book and magazine covers are made. The structural features of adhesive films obtained from polyvinyl acetate latex were determined, which have improved flexibility, elasticity, high adhesion and water resistance when water-soluble modifiers are added to them. An experimental determination was made of the possibilities of increasing the structural strength of semi-rigid book and magazine covers after gluing with modified binding adhesives, which did not significantly increase the thickness of the adhesive layer and did not change the contour geometry of the manufactured covers. It was proved that the adhesive mixtures used to modify the PVA dispersion did not affect the structural homogeneity of the glued spatial structure of the semi-rigid covers, and did not affect the appearance of external defects in the form of plane inhomogeneity, or point thickenings of the surface of the covers. The results of studies on the gluing of structural parts of reamers of semi-rigid covers with modified adhesive compositions create additional opportunities in planning the use of consumables in the manufacture of covers for strength indicators, predefined dimensional conditions for the use of modifier substances. Experimental studies have shown discreteness – growth, decrease in dimensional indicators of the strength of semi-rigid covers glued with modified adhesive compositions, contributes to the practical application of the results, both in the planning of technological processes and in the calculation of the cost of book production.

Дослідження структури композиційних теплоізоляційних матеріалів холодного спінювання

In the work the regularities of influence of components of liquid-glass composition on the formation of porous structure of composite thermal insulating materials, which include granulated blown liquid glass and binder, which is foamed with the help of gas-forming agent at ambient temperature, are investigated. The obligatory components of the binder are, apart from liquid glass, gas-forming agents, a surface-active substance and an active additive. As active additives in the production of these materials were used binder fillers alabaster and cement, which bind an excessive amount of water contained in the liquid glass in its crystal lattice and allow to increase the strength of insulation materials. Hydrogen peroxide and aluminium powder were used as gas-forming agents, which are easily dispersible in liquid glass. The formation of resistant foams is facilitated not only by the introduction of surfactants, but also by the use of polymer additives, which increase the viscosity of the system and mechanical strength of the foam, therefore OP-10 and polyvinyl acetate dispersion, which have good compatibility with liquid glass, were chosen as foam stabilizers. The structure of insulating materials was studied by means of electronic microscopy. As a result of the study, depending on the type and quantity of binder components, the following parameters of the structure of foamed materials were determined: transverse pore diameter, pore shape coefficient, the degree of inhomogeneity of the material structure, as well as its total porosity and volume content of closed pores. The conducted researches allowed to determine the optimal binder formulation for the production of these materials, which meets the main requirement — the occurrence of active centers should occur at the moment when gas dispersion in the matrix (liquid—glass composition) reaches the limit (saturation), thus achieving a homogeneous fine-pore material structure. The formation of uniform porous structure of thermal insulation materials provides low rates of their thermal conductivity and high strength, which allows their effective use for thermal insulation of various structures.

Heat Emission Kinetics and Hydration Behavior of Modified Polymer–Cement Mixtures for 3D Printing Construction

Abstract—The process of heat emission is investigated during the hydration of the binder in polymer–cement mixtures and mixtures modified by phloroglucinol–furfural superplasticizer. The specific binder hydration enthalpy in the presence of a polyvinyl acetate dispersion and redispersible polymer powder is determined. It is established that the specific enthalpy of polyvinyl acetate polymer–cement systems is positive, which indicates the endothermic nature of the overall process. The dependence of the absolute heat emission values in the initial periods of material hardening on the binder hydration time in the presence of organic mixture components (polyvinyl acetate and phloroglucinol–furfural modifier) is studied. It is proved that, when modifying polymer–cement systems, there is a decrease in the heat emission peak, a reduction in the timing of the initial hydration period, and an increase in the duration of the second (induction) period. The heat emission kinetic curves of the modified polyvinyl acetate–cement mixtures are presented, and the hydration behavior of the studied systems is considered. It is established that, in the initial period of hardening, polyvinyl acetate increases and phloroglucinol–furfural superplasticizer reduces the heat emission rate, while when modifying the polymer–cement system with a polymer in the form of a polymer dispersion, this process is partially balanced.