Consolidation particle adhesion

Many wood species, both hardwoods and softwoods, are used for particleboard however, the density of the particleboard should be higher than the density of the raw material to efficiently utilize the adhesive system. The compression of the particles, which is required for consolidation into the finished product, enhances the particle-particle contact, producing more inter-particle adhesive bonds as well as reducing the total void volume in the panel. With wood of density higher than the finished particleboard, the compression of the particles is lower and the resultant reduced interparticle contact and higher void volume adversely influence the physical and mechanical properties of the parti cleboard. 

Joints between different objects can be made in many ways. Carpentry joints are held by mechanical keying, hot-welded iron is held by the merging of the metal from the separate pieces, and dust is held on to the surface of plastics by the electrostatic attraction of dust particles for the surface. These phenomena depend on the physical properties of the objects themselves to create the joint. In conservation, an adhesive is employed to bridge and fill the gap between two objects. The adhesive is applied as a liquid, which forms a strong bond to the object s surface. The principles of adhesion between a polymer and object surface are relevant to coatings, consolidants and adhesives - and dirt. 

J. Tomas, Particle Adhesion Fundamentals and Bulk Powder Consolidation. Reliable Flow of Particulate Solids III, Porsgrunn, 1999, 641-656. 

J. Tomas Particle adhesion fundamentals and bulk powder consolidation. International Symposium "Reliable Flow of Particulate Solids III", Porsgrunn, 1999,641-656... 

J. Tomas, Particle Adhesion and Powder Flow Properties - Part 1 Instantaneous Elastic-Plastic Particle Contact Consolidation and Yield Loci, Powder Technology (2001), (submitted)... 

Adhesive-Coated Material. The addition of an adhesive-coated material [335] to proppants decreases the flowback of the particulates. Such adhesive-coated materials can be inorganic or organic fibers, flakes, and the like. The adhesive-coated material interacts mechanically with the proppant particles to prevent the flowback of particulates to the wellbore. The consolidation of a proppant also may occur via a polyurethane coating, which will slowly polymerize after the fracturing treatment because of a polyaddition process [1856]. 

Pressing Operation. The consolidation of the particle mat and polymerization of the adhesive to produce a particleboard panel is accomplished in a hot press. The mat is compressed and held at the desired thickness until the adhesive on the particle surfaces has polymerized and established adequate bridges between particles. The panel is then removed from the press, cooled, and sent to the finishing phase. 

Particleboards are composed of discrete particles of wood bonded together by a synthetic resin adhesive, most commonly urea-formaldehyde or phenol-formaldehyde. The material is consolidated and the resin cured under heat and pressure. The strength of the product depends mainly upon the adhesive and not upon fiber... 

Coconut Husk The husk represents 35% of the intact, mature coconut by weight. A number of products are derived from this by-product of oil production. Particles of husks may be consolidated with little or no adhesive (64). Pith is... 

Particleboard is produced by hammer-milling the material into small particles, spray application of adhesive to the particles, and consolidating a loose mat of the particles into a panel product with heat and pressure. All particleboards are currently made using a dry process, where air is used to randomise and distribute the particles prior to pressing. 

Dilute systems of dispersed particles. Agglomeration occurs due to particle-particle collisions followed by adhesion. For nonrigid particles, the collision/adhesion process may be followed, in turn, by coalescence into a single new particle. In the case of rigid particles, there may also be a consolidation (densification) step involving rearrangement of the particles and a reduction. 

The well-known failure hypotheses of Tresca, Coulomb-Mohr and the yield locus concept of Jenike [1] and Schwedes [2] as well as the Warren-Spring-Equations [3 to 7] were specified from Molerus [8, 9] by the cohesive steady-state flow criterion. The consolidation and non-rapid, frictional flow of fine and cohesive particulate solids was explained by acting adhesion forces in particle contacts [8]. 

Generalising these findings, the adhesion force Fho without any additional consolidation can be approached as a single rough sphere-sphere-contact. Herewith, Fro considers a characteristic hemispherical micro-roughness height or radius hr < d instead of particle size [24] ... 

Due to the consolidation function, a small slope stands for a free flowing particulate solid with very low adhesion level because of stiff particle contacts but a large inclination means a very cohesive powder flow behaviour because of soft particle contacts, see Fig. 1. 

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