Manufacture of flame retardant foaming board from waste papers reinforced with phenol-formaldehyde resin.
A new flame retardant and waterproof porous fiberboard was manufactured from waste newspapers by using a foaming agent and a reinforcing phenol-formaldehyde resin. To find the optimum conditions for forming fiberboard with high mechanical properties as well as flame retardant and waterproof characteristics, a series of experiments were performed with varying weight percentages of resin (w). The results indicate that the best quality of the fiberboard was obtained for w approximately 11%.
Flame resistant lignocellulosic-mineral composite particleboards
Abstract Lignocellulosic boards, including particleboards, fiber boards, flake boards and the like are among the most popular materials used in the building industry, for outfitting (furniture) and for interior decoration (wall and ceiling paneling). However, due to their unfavorable behavior under fire conditions, their use has often been limited, particularly in multistoreyed buildings as well as public edifices. At the INF, research on a new type of flame-resistant board is carried out in three different directions. The subject of this paper is the most recent development in the above research, namely a three-layer, non-flammable composite particleboard based on lignocellulosic particles and mineral filler – expanded vermiculite with urea-formaldehyde (U-F) resin as a binder. Boards of this type can be based on different lignocellulosic raw materials, e.g. wooden particles, annual bast plant waste (flax, hemp, jute, kenaf, etc.) such as shives. The production method of the composite boards and results of reaction-to-fire tests according to ISO 5660, as well as physical, mechanical and hygienic properties, are presented.
Failure Prediction of Smeared-Crack Formulations
The smeared-crack approach of strain-softening is a popular engineering concept for the numerical simulation of tensile failure processes in concrete and rock. Despite numerous publications on the equivalent constitutive formulation of cracked solids, very little is known about the predictive value of the smeared-crack approach, particularly when nonproportional load histories are considered. To this end, two failure indicators are examined at the constitutive level in order to assess the predicted failure mode of fixed and rotating crack concepts. The directional stiffness parameter is used to examine singularities of smeared-crack formulations, which signal continuous failure due to material branching. In contrast, the localization indicator is used to examine the formation of weak discontinuities, which precede incipient failure process when the continuum degrades into a discontinuum. In this paper both failure indicators will be used to assess the failure modes of the fixed and rotating crack formulations for two loading scenarios involving pure shear and combined tension with shear.