scholarly journals IMPROVING STRENGTH INDICATORS OF FSF PLYWOOD BY USING MODIFIING ADDITIVES TO BINDING AGENT

2020 ◽  
Vol 10 (1) ◽  
pp. 124-135
Author(s):  
A. Fedotov ◽  
Tat'yana Vahnina ◽  
Sergey Kotikov
Keyword(s):  
Tensile Strength ◽  
Active Sites ◽  
Water Resistance ◽  
Phenol Formaldehyde ◽  
Adhesive Layer ◽  
Strength Properties ◽  
Production Costs ◽  
Modifying Additives ◽  
Anhydrous Magnesium Chloride

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

Dry-Process Hardboards from Recycled Newsprint Paper Fibers

1992 ◽  
Vol 266 ◽  
Author(s):  
Andrzej M. Krzysik ◽  
John A. Youngquist ◽  
James M. Muehl ◽  
Roger M. Rowell ◽  
Poo Chow ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Mechanical Strength ◽  
Water Resistance ◽  
Wood Fiber ◽  
Strength Properties ◽  
Dry Process ◽  
Paper Fibers

AbstractDry-process hardboard represents a favorable option for recycling old newspaper fibers. However, dry-process boards tend to be less dimensionally stable than boards processed by other methods. Our objective was to determine the effects of various wood fiber (WF) to old newspaper (ONP) ratios (100:0, 50:50, and 0:100 WF/ONP) on the mechanical strength and water resistance of dry-process hardboards made from these fibers. Untreated and acetylated hardboards were made with 3 or 7 percent resin and 0.5 percent wax. Boards were tested for static bending and tensile strength properties and water resistance. As expected, increasing the resin level from 3 to 7 percent generally improved all measured properties. Acetylation substantially improved the water resistance of all boards; increasing the amount of ONP caused a corresponding deterioration in both mechanical properties and water resistance.

scholarly journals Influence of technological cracks of peeled vener on the shear strength of ultralam bars

2021 ◽  
Vol 244 ◽  
pp. 09010
Author(s):  
Stefania Mironova
Keyword(s):  
Shear Strength ◽  
Building Material ◽  
Phenol Formaldehyde ◽  
Adhesive Layer ◽  
Strength Properties ◽  
Glue Line ◽  
Adhesive Material ◽  
Laminated Veneer Lumber ◽  
Peeling Process ◽  
Veneer Surface

The aim of the research is to study the shear strength of laminated veneer lumber (LVL) when working on shear in four different planes. To determine the influence of the presence of technological cracks formed in the peeling process, an experiment was carried out for which four types of samples were used. The load was applied parallel and perpendicular to the glue line and the direction of the peeled veneer fibers. As tests have shown, the technological weakening of peeled veneer reduces the strength properties of a multilayer glued veneer bar, especially for shear along the glue lines and perpendicular to the direction of the peeled veneer fibers, where the maximum number of microcracks is located. The analysis of these microcracks is carried out and their widths are determined. The width of the studied cracks was from 152 to 94 μm. There is no adhesive layer in the microcracks of this building material, which may indicate insufficient wetting of the veneer surface with the adhesive material, or the difficulty of penetration of high-molecular phenol-formaldehyde glue into the cavity of microcracks.

scholarly journals INFLUENCE OF MODIFIERS ON THE CURING TIME OF THE PHENOL FORMALDEHYDE BINDER FOR PRESSING PANELS AT LOW TEMPERATURE MODE

2020 ◽  
Vol 9 (4) ◽  
pp. 99-108
Author(s):  
Tat'yana Vahnina ◽  
A. Fedotov ◽  
Andrey Titunin ◽  
Irina Susoeva
Keyword(s):  
Water Resistance ◽  
Phenol Formaldehyde ◽  
Dimethyl Sulfate ◽  
Spectroscopic Studies ◽  
Scientific Data ◽  
Iron Chloride ◽  
Formaldehyde Resin ◽  
Significant Deterioration ◽  
Modifying Additives ◽  
Temperature Ranges

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%.

scholarly journals THE INFLUENCE OF PRODUCTION PROCESS FACTORS ON THE INDICATORS OF PLYWOOD ON MODIFIED PHENOL-FORMALDEHYDE BINDER

2021 ◽  
Vol 11 (1) ◽  
pp. 88-100
Author(s):  
Aleksandr Fedotov ◽  
Tat'yana Vahnina ◽  
Sergey Kotikov
Keyword(s):  
Production Process ◽  
Ultimate Strength ◽  
Bending Strength ◽  
Phenol Formaldehyde ◽  
Physical And Mechanical Properties ◽  
Adhesive Layer ◽  
Production Costs ◽  
Thickness Swelling ◽  
Rational Combination ◽  
Process Factors

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

scholarly journals Welding of Prosthetic Alloys / Spawanie Stopów Protetycznych Typu Co-Cr

2015 ◽  
Vol 60 (4) ◽  
pp. 2703-2708
Author(s):  
M. Wojciechowska ◽  
E. Wołowiec-Korecka ◽  
L. Klimek
Keyword(s):  
Tensile Strength ◽  
Impact Strength ◽  
Laser Beam ◽  
Strength Properties ◽  
Comparative Assessment ◽  
Solid Metal ◽  
Strength Tests ◽  
Gas Burner ◽  
A New Technique

This paper presents the techniques of joining metal denture elements, used in prosthetic dentistry: the traditional soldering technique with a gas burner and a new technique of welding with a laser beam; the aim of the study was to make a comparative assessment of the quality of the joints in view of the possibility of applying them in prosthetic structures. Fractographic examinations were conducted along with tensile strength and impact strength tests, and the quality of the joints was assessed compared to the solid metal. The experiments have shown that the metal elements used to make dentures, joined by the technique which employs a laser beam, have better strength properties than those achieved with a gas burner.

scholarly journals Welding of Prosthetic Alloys

2015 ◽  
Vol 60 (1) ◽  
pp. 187-191
Author(s):  
M. Wojciechowska ◽  
E. Wołowiec ◽  
L. Klimek
Keyword(s):  
Tensile Strength ◽  
Impact Strength ◽  
Laser Beam ◽  
Strength Properties ◽  
Comparative Assessment ◽  
Solid Metal ◽  
Strength Tests ◽  
Gas Burner ◽  
A New Technique

Abstract This paper presents the techniques of joining metal denture elements, used in prosthetic dentistry: the traditional soldering technique with a gas burner and a new technique of welding with a laser beam; the aim of the study was to make a comparative assessment of the quality of the joints in view of the possibility of applying them in prosthetic structures. Fractographic examinations were conducted along with tensile strength and impact strength tests, and the quality of the joints was assessed compared to the solid metal. The experiments have shown that the metal elements used to make dentures, joined by the technique which employs a laser beam, have better strength properties than those achieved with a gas burner.

Increased dryness after pressing and wet web strength by utilizing foam application technology

TAPPI Journal ◽  
2016 ◽  
Vol 15 (11) ◽  
pp. 731-738 ◽  
Author(s):  
KARITA KINNUNEN-RAUDASKOSKI ◽  
KRISTIAN SALMINEN ◽  
JANI LEHMONEN ◽  
TUOMO HJELT
Keyword(s):  
Tensile Strength ◽  
Guar Gum ◽  
Paper Industry ◽  
Reference Sample ◽  
Strength Properties ◽  
Cellulose Microfibrils ◽  
Application Technology ◽  
Ethylene Vinyl Alcohol ◽  
Wet Pressing ◽  
Web Strength

Production cost savings by lowering basis weight has been a trend in papermaking. The strategy has been to decrease the amount of softwood kraft pulp and increase use of fillers and recycled fibers. These changes have a tendency to lower strength properties of both the wet and dry web. To compensate for the strength loss in the paper, a greater quantity of strength additives is often required, either dosed at the wet end or applied to the wet web by spray. In this pilot-scale study, it was shown how strength additives can be effectively applied with foam-based application technology. The technology can simultaneously increase dryness after wet pressing and enhance dry and wet web strength properties. Foam application of polyvinyl alcohol (PVA), ethylene vinyl alcohol (EVOH), carboxymethyl cellulose (CMC), guar gum, starch, and cellulose microfibrils (CMF) increased web dryness after wet pressing up to 5.2%-units compared to the reference sample. The enhanced dewatering with starch, guar gum, and CMF was detected with a bulk increase. Additionally, a significant increase in z-directional tensile strength of dry web and and in-plane tensile strength properties of wet web was obtained. Based on the results, foam application technology can be a very useful technology for several applications in the paper industry.

scholarly journals Evaluation of the Impact of Organic Fillers on Selected Properties of Organosilicon Polymer

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1103
Author(s):  
Sara Sarraj ◽  
Małgorzata Szymiczek ◽  
Tomasz Machoczek ◽  
Maciej Mrówka
Keyword(s):  
Tensile Strength ◽  
Natural Fiber ◽  
Accelerated Aging ◽  
Strength Properties ◽  
Visual Observation ◽  
Walnut Shell ◽  
Pistachio Shell ◽  
Thermoplastic Matrix ◽  
Static Tensile ◽  
The Impact

Eco-friendly composites are proposed to substitute commonly available polymers. Currently, wood–plastic composites and natural fiber-reinforced composites are gaining growing recognition in the industry, being mostly on the thermoplastic matrix. However, little data are available about the possibility of producing biocomposites on a silicone matrix. This study focused on assessing selected organic fillers’ impact (ground coffee waste (GCW), walnut shell (WS), brewers’ spent grains (BSG), pistachio shell (PS), and chestnut (CH)) on the physicochemical and mechanical properties of silicone-based materials. Density, hardness, rebound resilience, and static tensile strength of the obtained composites were tested, as well as the effect of accelerated aging under artificial seawater conditions. The results revealed changes in the material’s properties (minimal density changes, hardness variation, overall decreasing resilience, and decreased tensile strength properties). The aging test revealed certain bioactivities of the obtained composites. The degree of material degradation was assessed on the basis of the strength characteristics and visual observation. The investigation carried out indicated the impact of the filler’s type, chemical composition, and grain size on the obtained materials’ properties and shed light on the possibility of acquiring ecological silicone-based materials.

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