Showing papers in "Journal of Adhesion Science and Technology in 2011"

Decoding Powder Tabletability: Roles of Particle Adhesion and Plasticity

Abstract: Tabletability, the ability to make a tablet of adequate mechanical strength by powder compaction, is of paramount importance in the successful manufacture of tablet products. Poor tabletability is a persistent problem in the pharmaceutical industry. Tablet strength can be understood based on a qualitative model where contributions of bonding area and bonding strength are simultaneously considered. Formation and elimination of bonding area is related to compaction conditions, mechanical properties and particulate properties (such as particle size and shape). Plastic deformation emerges as the most important mechanism for creating a large bonding area among deformation mechanisms. Interfacial adhesion defines bonding strength and is dependent on the chemical nature of the materials involved. An analysis of how the chemical, mechanical and physical properties of a powder impact bonding strength and bonding areas leads to an understanding of their effects on powder tabletability. Appropriate use of this model...

Laser-Patterned Super-Hydrophobic Pure Metallic Substrates: Cassie to Wenzel Wetting Transitions

Abstract: A femtosecond laser was used to create microstructures on very pure metal surfaces The irradiated samples initially showed super-hydrophilic behavior With time and exposure to ambient air the contact angle increased to about 160° with very low hysteresis The surfaces supported the Cassie and Wenzel wetting states, depending on the technique used to deposit the water droplets The created surface morphologies were idealized with a geometric model that is an assembly of densely packed cylindrical pillars with semispherical caps Using this geometric model for calculation of the surface roughness, a theoretical Young contact angle of about 99° was calculated for all samples from the Wenzel and Cassie–Baxter equations While the value of 99° significantly differs from the measured hydrophilic contact angles on the polished pure metallic samples, it indicates that a laser-induced surface reaction must be responsible for the evolution of contact angles to super-hydrophobic ones and that this phenomenon is in

Advanced Icephobic Coatings

Abstract: Adhesion and excessive accumulation of atmospheric ice on the surface of exposed objects such as conductors of overhead power lines, cables and conductors in aluminum can have devastating economical and safety consequences as it was the case during the 1998 and 2007 ice storms in Canada and USA. Recent advances in the understanding of ice adhesion on various substrates and in materials science have spurred interest in developing new intrinsic icephobic materials. The aim of this paper is to review the most relevant research activities related to ice adhesion mechanisms and icephobic coating development during the recent years. This will allow a better comprehension of ice adhesion, and help determine more reliable and cost effective ways to develop icephobic coatings, In order to develop icephobic coatings three main groups of materials or surface treatment can be considered: (i) self-assembled monolayers with –CH3 or –CF3 groups oriented outward to the ice surface, (ii) coatings with a heterogeneous chem...

Effects of Temperature and Loading Rate on the Mechanical Properties of a High Temperature Epoxy Adhesive

Abstract: The variation of the mechanical properties of adhesives with temperature and strain rate is one of the most important factors to consider when designing a bonded joint due to the polymeric nature of adhesives. It is well known that adhesive strength generally shows temperature dependence. Moreover, in many structural applications, the applied loads can be dynamic and the design of the joint requires the knowledge of the high loading rate mechanical behaviour of the adhesive. In this study, the combined effect of the temperature and test speed on the tensile properties of a high temperature epoxy adhesive was investigated. Tensile tests were performed at three different test speeds and various temperatures (room temperature (RT) and high temperatures (100, 125 and 150°C)). The glass transition temperature (T g) of the epoxy adhesive investigated is approximately 155°C. The ultimate tensile stress decreased linearly with temperature (T) while increased logarithmically with the loading rate, which is in the ...

Strength Improvement of Adhesively-Bonded Joints Using a Reverse-Bent Geometry

Abstract: Adhesive bonding of components has become more efficient in recent years due to the developments in adhesive technology, which has resulted in higher peel and shear strengths, and also in allowable ductility up to failure. As a result, fastening and riveting methods are being progressively replaced by adhesive bonding, allowing a big step towards stronger and lighter unions. However, single-lap bonded joints still generate substantial peel and shear stress concentrations at the overlap edges that can be harmful to the structure, especially when using brittle adhesives that do not allow plasticization in these regions. In this work, a numerical and experimental study is performed to evaluate the feasibility of bending the adherends at the ends of the overlap for the strength improvement of single-lap aluminium joints bonded with a brittle and a ductile adhesive. Different combinations of joint eccentricity were tested, including absence of eccentricity, allowing the optimization of the joint. A Finite Elem...

Contact Angle Measurements on Smooth Nanocrystalline Cellulose (I) Thin Films

Abstract: Interactions of cellulose fiber surfaces with water and other liquids depend on surface morphology as well as intrinsic material properties. Smooth nanocrystalline cellulose (I) films can be used as models to study surface phenomena, where the effects of surface morphology and roughness are minimized. Contact angle measurements are particularly sensitive to surface roughness. In this work, we measured the advancing and receding contact angles for water on thin model cellulose (I) and regenerated cellulose (II) films. The advancing and receding contact angles on model cellulose (I) surfaces were lower than on cellulose (II) surfaces, and the contact angle hysteresis was also lower for the smooth model cellulose (I) surfaces prepared from nanocrystal suspensions. The surface free energy was evaluated for the various cellulose surfaces from contact angle measurements.

Single Lap Joints with Rounded Adherend Corners: Experimental Results and Strength Prediction

Abstract: The objective of the present study was to better understand the effect of the change in the geometry of the adherend corners on the stress distribution in single lap joints and, therefore, on the joint strength. Various degrees of rounding were studied and two different types of adhesives were used: one very brittle and another which had a large plastic deformation. Experimental results on the strength of joints with different degrees of rounding are presented. For joints bonded with brittle adhesives, the effect of the rounded adherend corners is larger than that with ductile adhesives. The strength of joints with brittle adhesives with a large radius adherend corner increases by about 40% compared to that with a sharp adherend corner. It is shown that for joints bonded with brittle adhesives, crack propagation occurs for a short period before it grows into catastrophic failure. However, for ductile adhesives, there is large adhesive yielding and small crack propagation before final failure. Another impo...

Prediction of Inter-particle Adhesion Force from Surface Energy and Surface Roughness

Abstract: Fine powder flow is a topic of great interest to industry, in particular for the pharmaceutical industry; a major concern being their poor flow behavior due to high cohesion. In this study, cohesion reduction, produced via surface modification, at the particle scale as well as bulk scale is addressed. The adhesion force model of Derjaguin–Muller–Toporov (DMT) was utilized to quantify the inter-particle adhesion force of both pure and surface modified fine aluminum powders (∼8 μm in size). Inverse Gas Chromatography (IGC) was utilized for the determination of surface energy of the samples, and Atomic Force Microscopy (AFM) was utilized to evaluate surface roughness of the powders. Surface modification of the original aluminum powders was done for the purpose of reduction in cohesiveness and improvement in flowability, employing either silane surface treatment or dry mechanical coating of nano-particles on the surface of original powders. For selected samples, the AFM was utilized for direct evaluation of t...

Single Lap Joints with Rounded Adherend Corners: Stress and Strain Analysis

Abstract: One of the major difficulties in designing adhesive lap joints is the stress singularity present at the adherend corners at the ends of the overlap. One way to overcome this problem is to assume that the corners have a certain degree of rounding. The objective of the present study was to better understand the effect of the change in the geometry of the adherend corners on the stress distribution and, therefore, on the joint strength. Various degrees of rounding were studied and two different types of adhesives were used, one very brittle and another which could sustain a large plastic deformation. The study gives a detailed stress and strain distribution around the rounded adherends using the finite element method. The major finding is that the stresses or strains in the adhesive layer of a joint with rounded adherend corners are finite. In real joints, adherends generally have small rounded corners. Consequently, the model with small radius corners may be used to represent real adherends.

Prevention of Ice Accretion on Aluminum Surfaces by Enhancing Their Hydrophobic Properties

Abstract: The accretion of ice on the surfaces of power network systems, aircraft, communication networks, etc., is known to cause serious problems that often lead to costly safety issues. An ideal solution would be to prevent ice from accumulating in the first place, rather than waiting for ice to accrete and then to de-ice which is both time-consuming and expensive. This may be accomplished by depositing coating materials that are icephobic. A low dielectric constant surface is expected to reduce the adhesion of ice due to the screening of mirror charges, thereby eliminating one of the strongest interaction forces — the electrostatic force of attraction — at the ice–surface interface. Superhydrophobic surfaces, which demonstrate high water-repellency due to the negligible contact area of water with these surfaces, are also expected to minimize the contact area of ice. In the present research work, both concepts were studied by producing superhydrophobic nanorough low-e (dielectric) surfaces on aluminum. Superhydr...

Production and Characterization of Cellulose Nanofibers from Wood Pulp

Abstract: Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low yields and high chemical costs, while mechanical methods require high energy costs. Methods to lower the energy costs of the mechanical methods have not been well documented in the literature. A bleached softwood kraft pulp was processed using a mechanical dispersion mill and a homogenizer to produce cellulose nanofibers. Two different commercial enzymes were used to pretreat the wood fibers before the mechanical treatments. The resulting nanofibers were characterized by light microscopy, atomic force microscopy, and inverse gas chromatography. Results indicate that the dispersion mill does not affect the overall pulp fiber fibrillation, but does help prepare the sample for the homogenizer. Most fibrillation occurs after three passes through the homogenizer. The enzyme pretr...

The Sintering Behavior of Electrically Conductive Adhesives Filled with Surface Modified Silver Nanowires

Abstract: Electrically conductive adhesives (ECAs) filled with sintered silver nanowires were prepared and the effect of different curing conditions on the electrical property of the ECAs was discussed. Silver nanowires with a diameter of 50–60 nm and a length of 2–3 μm were successfully synthesized through a polyol process and surface functionalized with dicarboxylic acid. Morphology studies showed that surface modified silver nanowires began to sinter at 200°C and became shorter and thicker, and eventually formed large chunks at higher temperatures. The conductive adhesives filled with 75 wt% of silver flakes and nanowires (3:2 weight ratio) were cured at different temperatures using two kinds of catalysts. The volume resistivity of the conductive adhesives cured at 300°C without a catalyst reached 5.8 × 10 –6 Ω cm. The dramatic improvement in the conductivity of the ECA is due to the sintering of silver nanowires and the high solid content resulting from the partial evaporation of polymer components.

Particle Interactions in Dry Powder Inhaler Unit Processes: A Review

Abstract: Recent development and methods of designing and optimizing dry powder formulations have extended the therapeutic potential of inhaled dosage forms. Successful drug delivery as indicated by a high and reproducible fine particle fraction, required to achieve the desired therapeutic effect while minimizing potential toxicity, depends on an understanding of the physico-chemical properties of powder blends, their performance and availability of adequate tools to screen and predict their behavior. The scope of this review includes three important perspectives for inhaled drug delivery: (1) Fundamental aspects of interparticulate interactions of pharmaceutical dry powder aerosols at rest and in resuspension; (2) The influences of pharmaceutical processing including milling, mixing, filling and storage, and their influence on powder dispersion; (3) Current strategies for formulation optimization and methods for in vitro aerosolization performance prediction.

The Effect of WS2 Nanotubes on the Properties of Epoxy-Based Nanocomposites

Abstract: In this paper we evaluated the effect of embedding inorganic nanotubes (INT) of tungsten disulfide (WS2) in an epoxy matrix, on the mechanical, thermal and adhesion properties of the resulting nanocomposites. The nanotube content spanned a range of values (0, 0.1, 0.3, 0.5 and 1.0 wt%), and the nanotube incorporation process consisted of a combination of both distributive (magnetic stirring) and dispersive (ultrasonic mixing) methods. The adhesion of the nanocomposites to an aluminum substrate was characterized by both a single lap shear and a T-peel test. The fracture toughness (K IC) of the nanocomposites was characterized by a standard compact tension (CT) plane-strain fracture test. The thermal properties of the nanocomposites were determined by dynamic mechanical thermal analysis (DMTA). Overall, the addition of INT-WS2 was found to improve the shear strength and peel properties of the nanocomposite, and to significantly improve its fracture toughness and glass transition temperature. The extent and ...

Fabrication of Novel Superhydrophobic Surfaces and Droplet Bouncing Behavior — Part 2: Water Droplet Impact Experiment on Superhydrophobic Surfaces Constructed Using ZnO Nanoparticles

Abstract: When a liquid droplet impacts a solid surface, it spreads up to a point and the kinetic energy is dissipated by viscosity, collision and surface energy during the process. The droplet can retract if the energy dissipation during the impact process which is only partly governed by surface properties is not too large. Otherwise, the droplet would stick to the surface or break into smaller droplets. In this second part, we introduced contact angle hysteresis (CAH) and studied the impact behavior between a water droplet and a superhydrophobic surface both theoretically and experimentally. On our superhydrophobic surface, the contact angle is about 155 degrees, so the kinetic energy of the droplet can be largely transferred to surface energy. Thus, under certain conditions, the droplet can fully bounce. The impact behavior of normal impact was analyzed theoretically. The critical falling heights for rebound (CFHR) were investigated on constructed ZnO-PDMS superhydrophobic surface in both normal and oblique impact conditions, and CFHR was found to increase with the increase of tilt angle. This shows that the normal Weber number (We(n)) is the major factor governing the rebound, while the tangential Weber number (We(t)) also has effect on the phenomenon. Compared to the energy dissipated by collision and viscosity, the influence of surface properties is relatively small. The adhesion number (N(a)) is the parameter determining the energy dissipated by surface tension and N(a) has direct relation with contact angle (CA) and CAH. (C) Koninklijke Brill NV, Leiden, 2011

Enzymes for Antifouling Strategies

Abstract: During the past decades, much effort has been made to find efficient alternative solutions to prevent and/or disrupt the adhesion of fouling organisms to surfaces. The use of enzymes emerges among the investigated approaches as one of the favorite candidate antifouling technologies due to enzymes' biodegradability and affordable prices. An overview of the different enzymatic antifouling strategies is presented, highlighting the most promising groups of enzymes, and their utilization upon surface-confinement to control biofouling. While the main strategies to control marine biofouling include the degradation of secreted adhesives and the production of antifouling compounds, the main concepts to control pathogenic biofilms are based on cell lysis and on the degradation of extracellular matrix polymers. Although immobilization can improve enzyme stability, activity and antifouling performance, up to date relatively few scientific articles concerning the use of immobilized enzymes to control biofouling have b...

Nanopatterned Metallic Surfaces: Their Wettability and Impact on Ice Friction

Abstract: A distinct surface microstructure was created on the surface of metal alloys and highly pure metals by using a one-step femtosecond laser process. After irradiation the surfaces show initially superhydrophilic behavior with complete wetting. With time and exposure to ambient air, however, the measured contact angles on these surfaces increase significantly. Eventually, all surfaces become hydrophobic and support Cassie-like hydrophobicity with contact angles beyond 150° and very low hysteresis. The increase in contact angle with time correlates with the amount of carbon detected on the irradiated surface, which suggests that the time dependency of the surface wettability depends on the combined effect of surface morphology and surface chemistry. The nanopatterned superhydrophobic substrates were tested in ice friction tests. At temperatures close to the melting point and relatively high speeds of the metal slider, the laser created nanoroughness and hydrophobicity significantly decrease ice friction. This...

Adhesion of Polymers in Paper Products from the Macroscopic to Molecular Level — An Overview

Abstract: Polymers are widely used in the manufacture, converting, and end-use of paper products where the quality of polymer adhesion is important at both paper and fiber levels. This article reviews a number of relevant theories of polymer adhesion, and such adhesion phenomena as revealed in recent investigations of the adhesion between polymer thin films and paper surfaces, the adhesion of polymer molecules to cellulose fibers, and surface forces measurements between model cellulosic surfaces. It is concluded that molecular adhesion and viscoelasticity of cellulose–polymer–cellulose joints play primary roles in the paper strength, which can be tailored by a rational design of polymer additives either as strength enhancers for strong paper products or debonding agents for soft paper tissues.

Contact Angle Hysteresis on Polymer Surfaces: An Experimental Study

Abstract: In order to characterize a solid surface, the commonly used approach is to measure the advancing and receding contact angles, i.e., the contact angle hysteresis. However, often an estimate of the average wettability of the solid–liquid system is required, which involves both the dry and wetted states of the surface. In this work, we measured advancing and receding contact angles on six polymer surfaces (polystyrene, poly(ethylene terephthalate), poly(methyl methacrylate), polycarbonate, unplasticized poly(vinyl chloride), and poly(tetrafluoroethylene)) with water, ethylene glycol and formamide using the sessile drop and captive bubble methods. We observed a general disagreement between these two methods in the advancing and receding contact angles values and the average contact angle determined separately by each method, although the contact angle hysteresis range mostly agreed. Surface mobility, swelling or liquid penetration might explain this behaviour. However, we found that the 'cross' averages of th...

A Soy Flour-Based Adhesive Reinforced by Low Addition of MUF Resin

Abstract: The desire to prepare a lower-cost soy-based adhesive has led to an interest in using the abundant and inexpensive soy flour (SF) as a substitute for expensive soy protein isolates (SPI) in wood adhesives However, the weakness of this adhesive is poor water-resistance and bonding strength due to a low protein content, which limits its application in the wood industry The objective of this research was to provide a simple and useful approach for improving the adhesion performance of SF-based adhesive by introducing a small addition of melamine-urea-formaldehyde (MUF) resin into the cured system The optimum addition level of MUF resin, as well as the adhesion performance and conformation change of SF-based adhesive, were investigated The analytical results indicated that the co-condensed methylene bridges were formed through the reaction of methylol groups of MUF resin with soy units during the hot-press process The addition of MUF resin, not only significantly decrease the viscosity of SF-based adhesi

Effect of Adhesive Compliance in the Assessment of Soft Adhesives with the Wedge Test

Abstract: Wedge tests are usually analysed assuming that the free, unbonded members may be treated as encastre cantilever beams. However, if the adhesive layer is sufficiently flexible (e. g., due to low elastic modulus), then significant strain in the bonded region may occur and lead to modification of the behaviour outside this region. Using in conjunction a sensitive strain gauge method on asymmetric wedge tests and a mathematical analysis developed from the work of Winkler, we conclude that the standard, simple beam theory approach significantly overestimates crack length for a supple adhesive layer. The present contribution mainly considers strain effects in the intact, bonded zone, rather than fracture per se. However, it is concluded that, if in fracture tests, the incorrect values of crack length obtained from the encastre beam assumption are employed to calculate fracture energy using the simpler model, there will be some self-compensation and little error in estimates of the latter will result (at least i...

Characterization of Surface Modification of Polyethersulfone Membrane

Abstract: Surface modification of polyethersulfone (PES) membrane surfaces using UV/ozone pretreatment with subsequent grafting and interfacial polymerization on membrane surface was investigated in order to improve the resistance of membrane surface to protein adsorption. The surface modifications were evaluated in terms of hydrophilicity, chemical composition of the surface and static protein adsorption. In both methods, poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG) and chitosan were chosen as hydrophilic polymers to chemically modify the commercial virgin PES membrane to render it more hydrophilic as these materials have excellent hydrophilic property. Modified PES membranes were characterized by contact angle and XPS. Contact angles of modified PES membranes were reduced by 19 to 58% of that of the virgin PES membrane. PES membrane modified with PEG shows higher wettability than other hydrophilic materials with the highest contact angle reduction shown for UV/ozone pretreated, PEG grafted PES membrane ...

Influence of Laser Surface Modification on Bonding Strength of Al/Mg Adhesive Joints

Abstract: Key properties of magnesium alloys, such as the high strength-to-density ratio, are driving the production of lightweight structural components in the automotive and aeronautical industries. Many efforts have been carried out on various aspects of processing and fabrication, but the joining of Mg alloys to dissimilar materials is a subject which attracted much research interest in the last decades. In the present work a preliminary investigation on the strength of Al/Mg (AA6082/AZ31B) single-lap epoxy bonded joints was carried out. To this aim, Mg and Al substrates were laser irradiated using a pulsed ytterbium fiber laser. For comparison, and in order to estimate the beneficial action of the laser surface treatment, single lap joints with grit-blasted substrates were prepared and tested. The interaction between laser treated surfaces and two different epoxy adhesives was also analyzed. Finally, the results and discussion were supported by scanning electron microscopy (SEM) and energy dispersive spectrosc...

Electrically Deformable Liquid Marbles

Abstract: Liquid marbles, which are droplets coated with a hydrophobic powder, were exposed to a uniform electric field. It was established that a threshold value of the electric field, 15 cgse, should be surmounted for deformation of liquid marbles. The shape of the marbles was described as a prolate spheroid. A semi-quantitative theory describing deformation of liquid marbles in a uniform electric field is presented. The scaling law relating the radius of the contact area of the marble to the applied electric field shows a satisfactory agreement with the experimental data.

Effect of moisture and temperature on the mechanical properties of an epoxy reinforced with boron carbide

Abstract: The degree of degradation in a polymer composite is directly related to the amount of moisture it absorbs. Plasticization and swelling are among the undesirable consequences of absorbed water. This effect is rather important in materials under severe requirements. The use of these composites as coatings requires studying changes in their properties. For this reason, the aim of this work was to study the effect of moisture and temperature on the mechanical properties of an epoxy reinforced with boron carbide. Different B4C particle sizes (7 and 23 μm) were studied, and the carbide used was 6 wt%. The specimens were exposed to two moisture environments (50 and 95% RH) at 60°C to quantify composite degradation level. Shore D hardness, three-point bending, and pin-on-disk wear tests were used to determine the effect of humid environments. Mechanical properties were determined at several exposure time intervals. Besides, the degradation process was analysed with differential scanning calorimetry (DSC) and infr...

Water Contact Angles on Poly(ethylene terephthalate) Film Exposed to Atmospheric Pressure Plasma

Abstract: The poly(ethylene terephthalate), PET, film was exposed to atmospheric pressure plasma under various plasma processing parameters. The wettability of the PET film immediately after the exposure and after storage in air, which was determined by the sessile drop method, was strongly dependent on the plasma processing parameters. The contact angle hysteresis on the plasma-exposed PET film was examined by the Wilhelmy method. It was found that the hydrophobic recovery of the PET surface on storage after the plasma exposure was observed only for the advancing contact angle and that the receding angle remained almost the same. These experimental findings were explained on the basis of the calculation by Johnson and Dettre for the advancing and receding contact angles on model heterogeneous surfaces.

Enhancing the Exterior Performance of Wood Joined by Linear and Rotational Welding

Abstract: Application of rosin, a wood derived, non-toxic, natural, inexpensive and easily and abundantly available natural material, to the wood faces to be joined by either linear vibration welding or rotational dowel welding has shown to greatly enhance the water resistance of welded wood joints. The method of application has been shown to have a marked effect on the results, with the application and drying of a diluted rosin solution to the wood surfaces before welding yielding the best results. The considerable improvement in water resistance does not still allow classification of the joints as fully exterior grade. However, dowel welding can now be used for protected exterior joints due to a combination of rosin waterproofing and joint geometry. Welded dowel joints holding together for longer than 455 days immersion in water indicate this to be the case. Rosin-treated linear vibration joints held together well in excess of 30 days but retained a measurable strength, in the best case, only up to 18 days water ...

Recent Advances in Surface Chemical Modification of Cellulose Fibres

Abstract: Over the last two decades, our research group has been involved in several approaches for chemical modification of cellulose fibre surfaces, with the aim to reduce their hydrophilic character and/or improve their adhesion strength to matrices in composite materials. Relevant advances were achieved recently by different modification strategies, namely (i) physical treatments, such as plasma; (ii) chemical grafting by click chemistry or by using polyether and polyester grafts and (iii) direct silanol-cellulose condensation with a prior hydrolysis treatment. The characterisation of the modified surfaces was performed using different characterisation techniques. The grafted materials were evaluated by elemental analysis, contact angle measurements, scanning electron microscopy, 13C-NMR CP-MAS, FTIR and X-ray photoelectron spectroscopy. The present paper reports the most relevant advances in the field of surface chemical modification of cellulose fibres achieved by our group over the last two years.

Study on the Performance of Hybrid Jute/Betel Nut Fiber Reinforced Polypropylene Composites

Abstract: The newest research and development results dealing with natural short fiber composites show new possibilities for environmentally-friendly materials. Current production trends clearly indicate the increased use of structural, nonstructural and molded natural fiber based composite panels for many applications. In our present work, two types of short natural fibers, namely jute and betel nut fibers, are employed as fillers for the formation of short fiber reinforced polypropylene composites in difference ratios (fiber content: 3, 5, 10 and 20 wt%) by hot-press moulding technique. Different jute-betel nut reinforced polypropylene hybrid composites were prepared in the ratio of 10:5, 10:10 and 10:15 wt% fiber contents with 85% PP, 80% PP and 75% PP, respectively. Mechanical properties of the composites, i.e., tensile, bending and impact strengths, were investigated. For better compatibility, jute and betel nut fibers were subjected to alkalization and the hybrid composites of alkalized jute/betel nut and PP ...

Extraction, Characterization and Utilization of Organosolv Miscanthus Lignin for the Conception of Environmentally Friendly Mixed Tannin/Lignin Wood Resins

Abstract: Lignin was extracted from Miscanthus × giganteus using two procedures: an aqueous-ethanol organosolv treatment and a two-step process involving a dilute acid pre-soaking step followed by an aqueous-ethanol organosolv treatment. The organosolv lignin was subjected to a comprehensive structural characterization by 13C and MALDI-TOF MS and used for the formulation of a green wood adhesive prepared with 100% natural resins. The best formulation was composed of 60% of mimosa tannin and 40% of glyoxalated lignin extracted using a 1-step organosolv treatment. This formulation, when applied to wooden test panels yielded good internal bond strength results, which was good enough to pass relevant international standard specifications for interior-grade panels.