PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL Volume 6, Number 1, 2020
Development of high-performance binderless fiberboards from wheat straw residue, Juan Domínguez-Robles et al, Construction and Building Materials, Vol.232 . This study aims to develop fully bio-based lignocellulosic fiberboards from wheat straw fibers without any additional bonding agents. The wheat straw biomass was used to produce a semichemical pulp, which was treated by means of enzymatic refining, on the one hand, and mechanical refining, on the other. The morphological analysis for both refined fibers was assessed and compared to that of wheat straw semichemical fibers. The results revealed that length and width were decreased, whereas, fines in length were increased after the enzymatic treatment and mechanical refining. The fibers were used to produce high-density fiberboards by means of wet process. The physical and mechanical properties of the resulting binderless fiberboards from both refined fibers were characterized and compared to that of fiberboards from wheat straw semichemical pulp and the commercial ones. In both cases, it was found that the mechanical properties of the fiberboards were significantly higher than those commercial fiberboards, as well as the required by the standard regulations. These results lead not only to synthetic resin elimination, but also to the exploration of using agricultural waste in several sectors, as the panel-housing could be. Use of basalt scrim to enhance mechanical properties of particleboards, Samuel Kramár et al, Construction and Building Materials, Vol.238 . The particleboard (PB) industry faces a high demand for light, low-cost panels of specific mechanical properties. This may be hard to fulfil because the density and strength of wood are linearly correlated. Use of proper materials and composition, however, may result in panels of a high strength- to-weight-ratio. This allows saving raw wood and energy as the strengthened PB is useful for high-load-bearing application. A promising reinforcing material are basalt fibres. In this study, basalt fibres in the form of a scrim provided reinforcement inside the PB panel. The scrim used had an area weight of 360 g·m −2 . Four compositions of 18 mm thick PBs and 640 kg·m −3 target density were produced using melamine-urea-formaldehyde (MUF) resin as the binder. Basalt scrims were positioned in the core, between the core and surface and in between both surface layers. The scrim used was either dry or additionally impregnated with MUF resin. The best variant proved to be the impregnated scrim placed in the middle of both surface layers. Its modulus of rupture (MOR) and modulus of elasticity (MOE) increased by 119 and 85% compared to the control panels, respectively. The setup also improved internal bond strength, screw withdrawal resistance and thickness swelling. Thus, basalt scrims at the outer positions significantly enhance the strength-to-weight-ratio of PBs. Improving operation in an industrial MDF flash dryer through physics-based, Pedro Santos et al, Control Engineering Practice, Vol.94 . Nonlinear model predictive control (NMPC) has increased popularity thanks to the availability of black-box models, systematically obtained from plant data via machine-learning procedures. Although this may be a good approach in the medium term, pure data-driven models quickly become outdated with changes in the process operation, so re-identification (training) routines are periodically required. Moreover, if the NMPC includes any economic objective to drive the process to a more efficient operation, these models often go beyond their validity range, which translates in a degraded control performance (high plant-model mismatch). In this work, the above issues are considered to model the drying section of an industrial medium density fibreboard (MDF) plant. The main contribution of this work is proposing a lumped- parameter grey-box model built upon first principles and completed with experimental equations, obtained from constrained regression with plant data. Upon this model, a moving-horizon estimator (MHE) is designed to estimate unmeasured inputs and states.
Technical Abstracts
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