New insulation fiberboards from sunflower cake with improved thermal and mechanical properties

Abstract

New thermal insulation fiberboards were manufactured by compression molding from a cake generated during the sunflower biorefinery. Fiberboards were cohesive mixtures of a natural binder and lignocellulosic fibers from sunflower cake. The natural binder ensured the board cohesion, and fibers acted as reinforcing fillers. The influence of molding conditions, i.e. binder type and binder content, on board density, mechanical and heat insulation properties was examined. The medium-density board containing 20% starch-based binder was a good compromise between mechanical and heat insulation properties (78 mW/m K thermal conductivity). It could be positioned on walls and ceilings for thermal insulation of buildings.

The thermo-mechano-chemical twin-screw reactor, a new perspective for the biorefinery of sunflower whole plant: aqueous extraction of oil and other biopolymers, and production of biodegradable fiberboards from cake

“…However, because part of the proteins in cake, that is globulins, revealed a thermoplastic behavior (Evon et al, 2010b), it could be also considered as a natural composite moldable into self-bonded materials (e.g. fiberboards) using thermopressing (Evon, 2008;Evon et al, 2010aEvon et al, , 2010bEvon et al, , 2012aEvon et al, , 2012bEvon et al, , 2012cEvon et al, , 2014Evon et al, , 2015aEvon et al, , 2015b. The interest for such a valorization for cake was confirmed in a recent market study.…”

“…• C) of insulation fiberboards was obtained through the development of a new compression molding process using very low pressure (87 kPa), applied during only 30 s molding time (Evon et al, 2015b), and this logically contributed to a large decrease in the energy consumed during molding (1.0 kW h/m 2 fiberboard). This process was conducted at ambient temperature and an aqueous solution made of an external binder with physical curing was added to the cake before molding.…”

“…• C: from 62.0 to 65.6 mW/m K, depending on its residual oil content (Evon et al, 2014(Evon et al, , 2015b. For a 52 mm bed height, this corresponded to a thermal resistance between 0.79 and 0.84 m 2 K/W, and such insulation ability of the cake was due to its very low bulk density (204-215 kg/m 3 ) as well as to its porous structure.…”

Investigation of Miscanthus and Sunflower Stalk Fiber-Reinforced Composites for Insulation Applications

“…Another possible use of vegetable fibers inside buildings results in their promising thermal insulation properties. For instance, lignocellulosic fibers from hemp [15], flax [15], or sunflower [16][17][18][19], all three cultivated in France, and from date palm [20] have already been used as insulating materials. e density of insulation boards often influences their thermal conductivity [20][21][22][23][24][25][26][27][28], and the lowest thermal conductivities are those of low-density materials.…”

“…However, the use of these mediumdensity materials may be considered in building insulations (e.g., walls and ceilings). Many examples of insulation boards are thus described in the recent literature (from the most insulating to the least one), e.g., from coconut husk (46-68 mW/m•K thermal conductivity with 250-350 kg/m 3 density) [25], coriander stalk fibers (56 mW/m•K thermal conductivity with 155 kg/m 3 density) [29], cake generated during biorefinery of sunflower whole plant in a twin-screw extruder (78-99 mW/m•K thermal conductivity with 358-687 kg/m 3 density) [17,19], cotton stalk fibers (82 mW/m•K thermal conductivity with 450 kg/m 3 density) [24], hemp fibers (90-108 mW/m•K thermal conductivity with 369-475 kg/m 3 density) [27], coconut coir (104 mW/m•K thermal conductivity with 540 kg/m 3 density) [21], and date palm fibers (150 mW/m•K thermal conductivity with 754 kg/m 3 density) [20]. Here, a correlation appears between the board density and its thermal conductivity: the denser the composite material, the poorer the thermal isolation ability is.…”