84 research outputs found
Reuse and Valorisation of Hemp Fibres and Rice Husk Particles for Fire Resistant Fibreboards and Particleboards
No full textThe present manuscript deals with the reuse and valorisation of agricultural wastes and by-products (namely, hemp fibres and rice husk particles) to produce fire retardant fibreboards and particleboards for applications in biobuilding. Since fire retardancy is one of the most important challenges, a detailed study on the thermal and flame retardant properties of the above materials assembled using starch as the binder and different ammonium dihydrogen phosphate contents as fire retardant agents, is proposed. The combustion properties have been investigated in developing fire conditions, employing a radiating heat flux of 35 kW/m2generated by a cone calorimeter. An optimised formulation able to make both fibreboards and particleboards not ignitable has been found and is predicted to be “A2/B” class in the European fire classification for building products. The resultant materials have proven to undergo pyrolysis and not to burn, favouring the formation of a dense and consistent final residue
All Natural High-Density Fiber- and Particleboards from Hemp Fibers or Rice Husk Particles
No full textIn the present study, long hemp fibers and rice husk particles have been used for producing all natural-based boards for building, automotive and in-door furniture, employing a simple and economic transformation process (namely, compression molding). In order to have the required consistence and mechanical strength, cornstarch was employed as binder. By this way, fiber- and particleboards have been prepared and characterized in terms of morphology, mechanical properties (flexural modulus and strength). The influence of different relative humidity levels on composite storage modulus and heat deflection temperatures has been investigated, as well. Long fibers turned out to be capable of sustaining approximately three times the load with respect to particles in standard conditions. Thermal, hygro- and photo stability of the above materials have been investigated under three ageing conditions: namely, (i) high temperature (thermal ageing), (ii) humidity plus high temperature (hygro-thermal ageing) and (iii) UV radiations (photo ageing). Regardless of the experimental ageing conditions adopted, fiberboards have shown good mechanical stability with a modest decrease of storage modulus (<20%) with respect to the values before exposure
UV-curable coatings for energy harvesting applications: Current state-of-the-art and future perspectives
No full textGenerally speaking, energy harvesting is an up-to-date technology that describes the possibility of capturing small amounts of energy (thermal, solar, or mechanical) from the surroundings and storing them as electrical energy for later uses when needed. Among the energy harvesting systems, the use of piezoelectric thin films and coatings is gaining increasing interest from both the academic and industrial communities, as these systems allow for the design and development of micro- and nano-scale devices, thanks to the possibility of being micromachined and to the added functionality offered by the electromechanical coupling. These peculiarities justify their use for different applications, ranging from high energy density harvesters to high sensitivity sensors, and even low power consumption and large displacement actuators. Further, the current focus of the research on piezoelectric energy harvesting coatings is shifting from fully inorganic to hybrid organic-inorganic (i.e., composite) systems, as the latter can offer higher flexibility (i.e., lower stiffness), making them more sensitive to small vibrations and therefore suitable for these specific harvesting conditions. In this regard, photoinduced polymerization (the so-called "UV-curing") has become a suitable and reliable technique for the manufacturing of piezoelectric composite systems, as it is a solvent-free approach that allows for transforming a liquid mixture of monomers/oligomers into a solid 3D network in a few seconds, with a very limited energy consumption and a very high conversion. Besides, as the UV-curing process is very fast, the dispersed ceramic piezoelectric phase is not prone to settle down in the liquid resin, hence ensuring its homogeneous distribution within the polymer network after curing and better piezoelectric performance. The present review aims to provide the reader with an up-to-date overview of UV-curable coatings for piezoelectric energy harvesting purposes, highlighting their potential and piezoelectric features; further, some perspectives about possible future developments will be proposed
HYBRID PIEZOELECTRIC FILMS FUNCTIONALIZED WITH ZnO NANOSTRUCTURES AND CELLULOSE NANOCRYSTALS
No full textRheological, Mechanical, Thermal and Electrical Properties of UHMWPE/CNC Composites
No full textIn this work, composites of ultra high molecular weight polyethylene (UHMWPE) and various loadings of
cellulose nanocrystals (CNCs) were prepared exploiting different methods. CNC-reinforced composites
exhibited improved Young’s modulus and yielding strength with respect to unfilled UHMWPE. The preparation method involving a solution mixing step was more effective than the dry method in promoting the achievement of embedded CNC particles preferentially located in the interfacial region between UHMWPE grains. Finally, UHMWPE/CNC composites obtained by solution mixing showed higher thermal conductivity and lower volume resistivity in comparison with those prepared by dry method, high-lighting that the proper selection of the processing method plays a key role in determining the material final performances
Structure of Syndiotactic Copolymers of Polypropylene with Ethylene.
No full textBook of Abstracts -P29
Influence of Mechanical Properties on the Piezoelectric Response of UV-Cured Composite Films Containing Different ZnO Morphologies
No full textZnO flower-like (ZFL) and needle (ZLN) structures were synthesized and embedded into UV-curable acrylic resin (EB), with the aim to study the effect of filler loading on the piezoelectric properties of the resulting composite films. The composites showed uniform dispersion of fillers within the polymer matrix. However, by increasing the filler amount, the number of aggregates increased, and ZnO fillers appeared not to be perfectly embedded in polymer film, indicating poor interaction with acrylic resin. The filler content increase caused an increase in glass transition temperature (T-g) and a decrease in storage modulus in the glassy state. In particular, compared with pure UV-cured EB (T-g = 50 degrees C), 10 wt.% ZFL and ZLN presented T-g values of 68 and 77 degrees C, respectively. The piezoelectric response generated by the polymer composites was good when measured at 19 Hz as a function of the acceleration; the RMS output voltages achieved at 5 g were 4.94 and 1.85 mV for the composite films containing ZFL and ZLN, respectively, at their maximum loading levels (i.e., 20 wt.%). Further, the RMS output voltage increase was not proportional to the filler loading; this finding was attributable to the decrease in the storage modulus of the composites at high ZnO loading rather than the dispersion of filler or the number of particles on the surface
Structure of Syndiotactic Copolymers of Polypropylene with Ethylene.
No full textBook of Abstracts -P29
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