Browsing by Keyword "Thermal properties"
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Item Fire retardancy of polypropylene composites reinforced with rice husks: From oxygen index measurements and cone calorimetry to large-scale single-burning-item tests: From oxygen index measurements and cone calorimetry to large-scale single-burning-item tests(2018-10-05) Schirp, Arne; Barrio, Aitor; BIOECONOMÍA Y CO2Rice husks containing 12 wt % inorganic silica were incorporated together with halogen‐free fire retardants in a polypropylene matrix and extruded into facade profiles. An increase in the amount of rice husks resulted in an increase in the oxygen index. The cone calorimetry measurements showed that all of the fire retardants tested significantly reduced the peak heat‐release rate (pHRR) and maximum average rate of heat emission (MARHE) of the formulations and moderately reduced total heat release. The best results in terms of MARHE were achieved for the formulation including 24% melamine‐coated ammonium polyphosphate. pHRR and MARHE were reduced with increasing amount of rice husks. Single‐burning‐item (SBI) tests were performed for the extruded profiles based on rice husks and, for comparison, wood flour. In the best case, a B‐s2, d0 classification was obtained. The results obtained from cone calorimetry and SBI tests were in agreement. Inc. J. Appl. Polym. Sci. 2018, 135, 46654.Item Free-standing graphene films embedded in epoxy resin with enhanced thermal properties(2020-03) Bustero, Izaskun; Gaztelumendi, Idoia; Obieta, Isabel; Mendizabal, María Asun; Zurutuza, Amaia; Ortega, Amaya; Alonso, Beatriz; PRINTEX; POLIMEROS; Tecnalia Research & InnovationThe poor thermal conductivity of polymer composites has long been a deterrent to their increased use in high-end aerospace or defence applications. This study describes a new approach for the incorporation of graphene in an epoxy resin, through the addition of graphene as free-standing film in the polymeric matrix. The electrical and thermal conductivity of composites embedding two different free-standing graphene films was compared to composites with embedded carbon nanotube buckypapers (CNT-BP). Considerably higher thermal conductivity values than those achieved with conventional dispersing methods of graphene or CNTs in epoxy resins were obtained. The characterisation was complemented with a study of the structure at the microscale by cross-sectional scanning electron microscopy (SEM) images and a thermogravimetric analysis (TGA). The films are preconditioned in order to incorporate them into the composites, and the complete manufacturing process proposed allows the production and processing of these materials in large batches. The high thermal conductivity obtained for the composites opens the way for their use in demanding thermal management applications, such as electronic enclosures or platforms facing critical temperature loads.Item Thermophysical and radiative properties of pressureless sintered SiC and ZrB2-SiC laminates(2018-09) Padovano, Elisa; Badini, Claudio; Mergia, Konstantina; Barcena, Jorge; EXTREMATThe evaluation of thermal and radiative properties of materials to be used as a hot part of thermal protection systems is a key issue for the design process of the HTC and UHTC components. Ceramic laminates with composition 100 vol%SiC and 80 vol%ZrB2-20 vol%SiC were prepared by the tape casting technique and pressureless sintered. Thermal properties such as the thermal expansion coefficient, specific heat, thermal diffusivity and conductivity were measured; in addition the total emissivity was evaluated. A comparison of the thermal behavior of these two kinds of laminates is made. Moreover their possible integration in a unique structure is discussed.