Water Soak Test Research Articles

Bio-Based Wood Adhesive from Camelina Protein (a Biodiesel Residue) and Depolymerized Lignin with Improved Water Resistance.

The aim of this study was to improve water resistance of camelina protein (CP) for wood adhesives with depolymerized lignin. Kraft lignin was depolymerized by H2O2-induced oxidation in the presence of ultrasound (US) irradiation to reduce lignin’s particle size and thermal stability and increase the hydroxyl group. Coupling with depolymerized lignin camelina protein exhibited increased hydrophobicity. Fluorescence spectroscopy analysis revealed that the oxidation treatment of lignin further stimulated the hydrophobization effect of the protein–lignin copolymer due to the increased reactivity of depolymerized lignin to camelina protein. Accordingly, the water resistance of CP–lignin adhesives was significantly improved. When copolymerized with US-induced oxidized lignin, the camelina protein had increased wet shear adhesion strength from 0.28 to 1.43 MPa, with wood panels passing the three-cycle water-soaking test. The CP resin, with depolymerized lignin as an economical, green, and bio-based hydrophobic enhancer, provided an alternative to the petroleum-based and other edible protein-based adhesives, such as soy protein.

Effect of Ammonium Polyphosphate to Aluminum Hydroxide Mass Ratio on the Properties of Wood-Flour/Polypropylene Composites.

Two halogen-free inorganic flame retardants, ammonium polyphosphate (APP) and aluminum hydroxide (ATH) were added to wood-flour/polypropylene composites (WPCs) at different APP to ATH mass ratios (APP/ATH ratios), with a constant total loading of 30 wt % (30% by mass). Water soaking tests indicated a low hygroscopicity and/or solubility of ATH as compared to APP. Mechanical property tests showed that the flexural properties were not significantly affected by the APP/ATH ratio, while the impact strength appeared to increase with the increasing ATH/APP ratio. Cone calorimetry indicated that APP appeared to be more effective than ATH in reducing the peak of heat release rate (PHRR). However, when compared to the neat WPCs, total smoke release decreased with the addition of ATH but increased with the addition of APP. Noticeably, WPCs containing the combination of 20 wt % APP and 10 wt % ATH (WPC/APP-20/ATH-10) showed the lowest PHRR and total heat release in all of the formulations. WPCs combustion residues were analyzed by scanning electron microscopy, laser Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis coupled with FTIR spectroscopy was used to identify the organic volatiles that were produced during the thermal decomposition of WPCs. WPC/APP-20/ATH-10 showed the most compact carbonaceous residue with the highest degree of graphitization.

Characteristic properties of glass fiber reinforced sugarcane bagasse medium density fiber board

Medium density fiberboard (MDF) is one of the wood composites which are used widely in the furniture industry. Therefore, its strengthening is required. Sandwiched material is manufactured by inserting sugarcane bagasse medium density fiberboard between the glass fiber reinforced laminates in just the same fashion as a sandwich. A hand lay-up technique is used to prepare the sandwiched specimen, in which the medium density fiberboard plate is put in between two woven layers of glass fiber epoxy laminates. Tensile and bending tests are done to investigate efficiently the tensile and flexural behaviors for the MDF strengthening process. In addition, compact tension and center notch specimen tests are carried out to obtain the effect of the modification performed for the MDF main material on fracture toughness. Moreover, a water soaking test is held out, and fungal bioassay resistance is investigated to obtain some of the novel material environments. The results illustrate that both tensile and flexural strength are extremely modified and increased. Besides, the results show compatibility and bonding between layered material and medium density fiberboard plate. The fracture toughness is greatly increased, and both tests can be met as regards fracture toughness tests for such novel composite material. The novel material has high resistance to fungal creation, which helps it to be utilized in medical furniture. Finally, it is found that only a very little percentage of absorption is established for the novel produced material.

ОБ ОСОБЕННОСТЯХ РОСТА ТРЕЩИН В ВЯЗКО-УПРУГОЙ СРЕДЕ С РАЗВИТОЙ ИЕРАРХИЧЕСКОЙ СТРУКТУРОЙ

The study of physical mechanisms of rock materials destruction allows obtaining the information necessary for the development of new technologies for mining and processing of minerals. Furthermore, such knowledge makes it possible to assess in real-life conditions the influence of external factors, for example, water, on the strength characteristics of mine workings and constructions, including the underground ones. The authors study the deformation behavior and special aspects of the destruction of small-sized specimens cut from the model viscoelastic materials – rock materials (carbonaceous quartzite, serpentinite, and artificial sandstone) under the diametrical compression – indirect stretching. Laboratory studies and subsequent modeling of the structure and properties of rock materials performed on small-sized specimens make it possible to solve the task not attracting the expensive test equipment and without violating the integrity of the specimens. During the study, small-sized specimens in the form of cylinders were produced from model viscoelastic materials. The mechanical properties of carbonaceous quartzite, serpentinite, and artificial sandstone specimens were estimated in the initial state and after a 24-hour water soak test. The study showed the influence of water on the change of a type of the specimens’ deformation behavior. The authors mapped the specimens’ side surfaces and created the topograms of the working surfaces before and after the tests. Based on them, the metallographic analysis of the geometric characteristics of cracks was performed at the macro- and microscopic levels. It was suggested that the change of a type of deformation behavior of rock materials, as well as the decrease in the strength properties of test rock materials specimens under the influence of water, are explained by the Rehbinder effect mechanisms.

Labile Extractable Urea-Formaldehyde Resin Components from Medium-Density Fiberboard*

Abstract Urea-formaldehyde (UF) resin is the predominant adhesive used in the manufacture of medium-density fiberboard (MDF). While it is well known that this resin is susceptible to moisture and hydrolysis, the present study determined that MDF panels lose a significant quantity of UF resin components in panel water soaking tests. Panel mass and %N losses indicate that MDF panels lose 48 to 66 percent of resin components during water soaking tests. Chemical analysis revealed that the labile extractable resin components included urea and monomeric and low-molecular-weight UF oligomers. Panel formaldehyde emissions were linked to the proportions of extractable UF resin oligomers. The results have implications for panel performance and the extent of resin cure achievable in manufacturing MDF.

Influence of pressing parameters on mechanical and physical properties of self-bonded laminated beech boards

Five-ply self-bonded boards were obtained by pressing beech veneers parallel to the grain without additional adhesives, steam or pre-treatment. Fifteen different combinations of pressing parameters were tested, including temperature (200°C, 225°C and 250°C), pressure (4, 5 and 6 MPa) and pressing time (240, 300 and 360 seconds). Due to severe pressing conditions, the new product showed a higher density and different properties compared to a conventionally glued laminated wooden board. The self-bonding quality was assessed through dry shear strength tests, through a three-point bending test and a water-soaking test at 20°C. The dimensions in the cross section of the boards were measured after soaking in water. Results show that the choice of pressing parameters affects all the mechanical and physical properties tested. A statistical analysis revealed that the pressing temperature is the most influential parameter. Boards pressed at 200°C delaminated rapidly in water, whereas boards pressed at 225°C delaminated only at core-positioned layers after 48 hours and boards pressed at 250°C did not delaminate at all in water. Compared to panels pressed at lower temperatures, boards pressed at 250°C had the highest density, a higher shear and bending strength and a lower water absorption.

UV-polymerisable, phosphorus-containing, flame-retardant surface coatings for glass fibre-reinforced epoxy composites

Abstract A vinyl phosphonic acid based flame retardant coating has been applied on the surface of a glass-fibre reinforced epoxy (GRE) composite substrate using a UV polymerisation technique. On exposure to heat the poly (vinyl phosphonic acid) (PVPA) coating thus obtained, intumesces and acts as a thermal insulator, providing active fire protection to the composite structure. Samples with ∼300 and 500 μm thick coatings were prepared. The fire performance of the coated GRE composite was studied by cone calorimetry at 35 and 50 kW/m 2 heat fluxes. While the sample with ∼500 μm thick coating did not ignite at both heat fluxes, the one with the ∼300 μm thick coating ignited at 50 kW/m 2 , however the time-to-ignition was delayed from 60 s in the uncoated sample to 195 s and the peak heat release rate reduced from 572 kW/m 2 to 86 kW/m 2 . The coatings did not peel off when subjected to a tape pull test and resisted cracking/debonding during an impact drop test of up to 5 J energy. However, the coatings are hydrophilic, showing significant mass loss in a water soak test. The improvement of the hydrophobicity of these coatings is a focus of our future research.

The Effects of Adding Melamine at Different Resin Synthesis Points of Low Mole Ratio Urea-Melamine-Formaldehyde (UMF) Resins

Low mole ratio urea-melamine-formaldehyde (UMF) resins synthesized with 2.5% and 5.0% melamine levels added at the beginning, middle, and end points of the first alkaline step of the typical urea-formaldehyde (UF) resin synthesis procedure were compared with typical UMF resins synthesized with melamine additions made at the final alkaline step. Various resin analysis, particleboard preparation, physical performance, and formaldehyde emission level tests were carried out. UMF resins synthesized with melamine additions at the beginning of the first alkaline step showed adequate storage lives of 2 to 3 weeks, and their particleboard bonding tests showed small but significant improvements in water soak test values, while formaldehyde content values were slightly higher in comparison with typical UMF resins. The particleboards showed adequate board strength and the formaldehyde contents were relatively low to qualify for the E1 Class of European Standards. UMF resins synthesized with melamine addition made at the middle and end of the first alkaline step were highly turbid and showed chemical structure differences and very short storage lives and the resin synthesis procedures were concluded to be of little practical value.

Investigation of Low Mole Ratio UF and UMF Resins Aimed at Lowering the Formaldehyde Emission Potential of Wood Composite Boards

Urea-melamine-formaldehyde (UMF) resins with 2.5% and 5.0% melamine levels added at the beginning of the third step of the typical urea-formaldehyde (UF) synthesis procedure were synthesized with an F/(U+M) mole ratio of 1.05 and evaluated as particleboard binders to investigate the positive effects of melamine on the formaldehyde content and physical performance of boards. Resins were tested for storage properties and analyzed by 13C NMR. Curing catalysts were studied, curing rates were measured, and laboratory particleboards were prepared and tested for formaldehyde contents as well as strength and water-soak test values. The UMF resins resulted in slower curing rates but had adequate board strength values. The formaldehyde content values were within the newly created California emission law (5.2 to 8.0 mg/100 g board). Another objective of this work was to establish the baseline performance of these resins for use in subsequent studies that will aim to reveal the effects of methylene-ether group contents on formaldehyde emissions.

HEAT APPLIED CHITOSAN TREATMENT ON HARDWOOD CHIPS TO IMPROVE PHYSICAL AND MECHANICAL PROPERTIES OF PARTICLEBOARD

High-heat treatment after surface application of chitosan was used in an effort to improve physical and mechanical performances of particleboard. Particleboard is mainly used in the furniture industry and also used as a home decoration material; however, it has a poor dimensional stability. In this work, hardwood chips were obtained from a commercial plant; half of the chips were used for the control panels without chitosan treatment, and the other half were treated with chitosan acetate solutions (2% wt). Those chitosan-treated particles were also exposed to extra high-heat (140°C) treatment for 90 minutes to convert chitosan acetate back to chitin. Liquid phenol-formaldehyde resin was sprayed onto dry particles at a level of 6 and 7% (wt) based upon oven-dry weight. The mat was pressed (200°C) for 11 minutes to form 19 mm thickness and a target of 0.63 g cm-3 density panels. Thickness swelling, linear expansion, and water gain of the treated panels were reduced over untreated panels during a 24-hour water-soak test. In addition, chitosan-treated panels showed better internal bond strength than control panels. Static bending test results showed a negative effect for the chitosan treated particleboard.

Reliability of low-index polymer coated double-clad fibers used in fiber lasers and amplifiers

The reliability of low-index polymer coated double-clad (DC) fibers used in the manufacture of fiber lasers and amplifiers has not received adequate attention. This paper evaluates the mechanical reliability of fibers, using standard fiber optic test procedures, and compares the performance of the DC fibers to the GR-20-CORE standard adopted by the industry. An 85 °C hot water soak test is proposed as an accelerated test to evaluate a low-index polymer coated DC fiber performance with prolonged exposure to temperature and humidity conditions experienced during storage and operation of fiber lasers. The test is used to evaluate DC fibers with three different coatings, including a specially engineered coating, and benchmark fibers from competitors. The data in this paper demonstrate that a dual acrylate coated DC fiber, using the specially engineered coating, has median failure stress values of over 700 kpsi and an average stress corrosion parameter of 21, well exceeding the recommended industry minimum values of 550 kpsi and 18, respectively. The accelerated temperature and humidity aging test clearly demonstrates that DC fibers with specially engineered coatings have 2 to 3 orders of magnitude better optical reliability. Such remarkable optical and mechanical performance significantly alleviates long term reliability concerns of fiber lasers and amplifiers.

Silica Sol-Gel Film on Bright Nickel Plating of Steel A3 Substrate

At present, ceramic coatings have attracted more and more attention for its good resistance, good chemical stability, and high temperature resistant, hydrophobic and other properties. SiO2 sol was prepared by chelated silicon powders to prepare SiO2 sol-gel film on the nickel plating layer. Pre-plating ordinary bright nickel-plating layer and composite bright nickel plating layer on the iron surface in advance, research some properties such as abrasion resistance, porosity, and NaCl solution soak test of SiO2 sol-gel films by changing the times of immersing SiO2 sol and baking temperature after immersing. The results show that: The time of emerging rust points for sol-gel coating on composite bright nickel-plated is much longer than that on ordinary bright nickel-plated in salt water soak test. The porosity of sol-gel coatings on composite bright nickel-plated is lower than that on ordinary bright nickel-plated. When the drying temperature is at 400°C or 500°C, the porosity rate is zero for the composite bright nickel without coatings or coated with any times of sol. It can improve wear resistance of the composite bright coating when immersing SiO2 sol at 500°C for 3 to 5 times. Porosity of SiO2 sol-gel coatings on the ordinary bright nickel layer is zero when baking at 500°C, immersing 3 times or more than 3 times. The best drying temperature is at 500°C, the best immersing times is 4 times to obtain better corrosion resistance for the bright nickel deposits. The color of the better appearance for a film is rainbow, its drying temperature of 500°C, immersing 4 times.

Properties of Strandboard Panels Manufactured from Eastern Redcedar

This study evaluated physical and mechanical properties of experimental strandboard panels with random flake alignment manufactured from eastern redcedar (Juniperus virginiana L.) logs. Panels were made at two density levels of 0.65 g/cm3 and 0.78 g/cm3 using phenol formaldehyde adhesive applied at a rate of 8%. Mechanical properties including modulus of elasticity and modulus of rupture, and internal bond strength of the panels in addition to their thickness swelling characteristics were evaluated. As expected, mechanical properties of the samples improved with increasing panel density. Thickness swelling of the samples for 2- and 24-h water soaking test ranged from 6.32% to 18.41%. Both physical and mechanical properties of the panels showed acceptable results, comparable to those found in past studies using other species to manufacture similar types of product. Based on initial findings of this study it appears that eastern redcedar, which is an under-utilized invasive resource, has potential as a raw material for structural panel manufacture.

Hydrofluoric-Acid-Resistant and Hydrophobic Pure-Silica-Zeolite MEL Low-Dielectric-Constant Films

A new technique for the silylation of pure-silica-zeolite MEL low-k films has been developed in which the spin-on films are calcined directly in trimethylchlorosilane or 1,1,1,3,3,3-hexamethyldisilazane (HMDS) in order to protect the films against corrosive wet etch chemicals and ambient moisture adsorption. In an alternative procedure, HMDS is also added to the zeolite suspension before film preparation. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water-soak tests, and HF etch tests are performed to characterize the films. The dielectric constant is as low as 1.51, and the films resist HF attack up to 5.5 min. These properties are highly desirable by the semiconductor industry for next-generation microprocessors.

Studies on Melamine Formaldehyde (MF) Loaded Polyvinyl Acetate—Polyester Nonwoven Fabric Composites

A series of composites is fabricated by impregnating the needled polyester nonwoven fabric in polyvinyl acetate (PVAc) latex. The effects of loading different amounts of melamine formaldehyde (MF) into PVAc on the physicomechanical properties of the composites have been studied. Percentage water absorption of composites have been determined both at room temperature for 24 h and in boiling water for 2 h. Heat aging studies conducted at 150 and 200 °C reveal that the composites have better dimensional stability at 150°C. The effect of salt water soaking at different temperatures viz., 30, 50, and 70°C on the mechanical properties, such as tensile strength, percentage elongation, and stitch tear strength has been studied. Vertical flammability test shows that the increase in the MF content has enhanced the flame resistance of the composites. The cyclic water-soaking test of the composites exhibits a reduction in thickness swelling with increase in the MF content in the system.

Some of the Properties of Three-layer Particleboard Panels Made from Under-utilized Species in Oklahoma

The objective of this study is to determine some of the properties of experimental three-layer particleboard panels made from osage orange (Maclura pomifera) and eastern redcedar (Juniperus virginiana L.), which are considered as invasive under-utilized species in Oklahoma. Static bending, internal bond strength, thickness swelling, and surface roughness characteristics of experimental panels made from particles of two species and their half and half mix are investigated. Whole-tree chipped material is used to manufacture experimental panels. The samples are tested for their mechanical strength and physical stability properties according to the procedures defined by ASTM D-1037. The modulus of elasticity of the panels made from eastern redcedar is 16.6 and 15.5% higher than the ones made from osage orange and mixed particles, respectively. Overall mechanical properties of the panels are not statistically different from each other at the 95% confidence level. Thickness swelling of the samples range from 17.4 to 23.2% as a result of 2- and 24-h water soaking tests. All panels yield adequate bending strength, stiffness, and thickness swelling. Surface characteristics of the samples are also evaluated employing a stylus type equipment. Two parameters, average roughness (Ra) and maximum roughness (Rmax) are used as indicators and it has been found that all the specimens have a relatively rough surface as substrate for typical overlaying applications.

Correlação entre absorção de água e tempo de cozimento de cultivares de feijão

O objetivo deste trabalho foi analisar o comportamento de cultivares de feijão quanto aos testes da capacidade de absorção da água pelos grãos e do tempo de cozimento, bem como avaliar correlações entre essas características visando à identificação precoce de linhagens de fácil cozimento. Foi adotado o delineamento experimental inteiramente casualizado, arranjado em fatorial 2 x 9, com três repetições. As cultivares utilizadas foram TPS Nobre e Pérola e os grãos foram imersos em água destilada durante 2 a 18 horas. Os resultados obtidos evidenciaram que a capacidade de absorção da água pelos grãos aumentou com o tempo em que permaneceram embebidos, até atingir o máximo de hidratação: 13h7min e 13h12min para as cultivares TPS Nobre e Pérola, respectivamente. O tempo de cozimento diminuiu à medida que os grãos permaneceram imersos até 12h49min, para as duas cultivares. A capacidade de absorção da água pelos grãos e o tempo de cozimento apresentaram correlação negativa e significativa.

Dependence of reaction kinetics and physical and mechanical properties on the reaction systems of acetylation II: physical and mechanical properties

Acetylation of wood was carried out in acetic anhydride only, acetic anhydride/xylene 1 : 1 (v/v), and acetic anhydride/pyridine 4 : 1 (v/v) solutions. The antishrink efficiency (ASE), hygroscopic properties, vibrational properties, and bending strength were compared among the three reaction solutions. The ASE was a simple function of weight gain (WG); the equilibrium moisture content at a given WG differed among the reaction solutions. Based on this fact and the results of repeated water soaking and oven-drying tests, it was found that the bulking effect was a major factor, and that decreased hygroscopicity contributes only slightly to the dimensional stabilization by acetylation. The difference in equilibrium moisture content among reaction solutions appears more significant in block samples than wood meal, probably due to the fiber-to-fiber bonds in the former. The tendencies for change in the specific Young’s modulus and the loss tangent differed among reaction solutions, whereas in the static bending test the difference was not marked.

Improvement of white pinewood properties by impregnation with thiourea-formaldehyde resin and orthophosphoric acid

White pinewood was impregnated with thiourea–formaldehyde (TUF) resin and orthophosphoric acid (OPA) as a crosslinking agent. The best weight gains (55–138%) were obtained after impregnation with an aqueous solution of TUF resin for 1 h and impregnation with aqueous solutions of OPA at different concentrations for 1 h. Water uptake of treated wood was found to be 23% after a water-soaking test of 168 h, and a maximum antiswell efficiency was found to be 18% for a 85% OPA solution. Compression strength of the treated wood also improved with the highest value 62 KN/m2 for wood treated with a 70% OPA solution versus a value of 40 KN/m2 for untreated samples. Fire retardancy of the treated wood samples was also improved based on concentration of OPA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 390–397, 2000

Physical properties of strawboard as affected by processing parameters

Wheat straw has been recently considered as an alternative to wood fibers in manufacturing particle boards. The objective of this study was to investigate the effects of processing parameters on straw particle board quality. Commercial ground wheat straw was used in a full factorial experimental design to examine the effects of three processing variables (initial straw moisture content (MC), resin binder content (BC), and press temperature) on strawboard physical and mechanical properties. The MC was tested between 2 and 12%, BC between 2 and 8%, and press temperature between 135 and 218°C. Strawboard density was held constant by controlling the gap in the press mold. Dimensional stability and water resistance was determined by a 24-h water-soak test, and mechanical properties by a three-point flexural test. In the tested parameter range, BC was the most significant factor affecting the strawboard dimensional stability, water resistance and mechanical properties. Initial straw MC was the second most significant factor influencing strawboard quality. MC had a more significant effect on board mechanical properties than on dimensional stability. Press temperature had a more significant effect on the strawboard dimensional stability than on mechanical properties.