Thermo-Mechanical Behaviour of the Raffinate Resulting from the Aqueous Extraction of Sunflower whole Plant in Twin-Screw Extruder: Manufacturing of Biodegradable Agromaterials by Thermo-Pressing

Abstract

Biorefinery of sunflower whole plant can be realized using a twin-screw extruder. Thermo-mechanical fractionation and aqueous extraction are conducted simultaneously. A filter section is outfitted along the barrel to collect continuously an extract and a raffinate (cake meal). Oil yield obtained is 53%. Proteins are partly extracted at the same time, just as pectins and hemicelluloses. Protein yield is 46%. Cake meal is relatively moist (66% for the moisture content). It is first dried to make easier its conservation. It is largely composed of lignocellulosic fibres (59% of the dry matter) from depithed stalk. Lipid content is 13% of the dry matter or 35% of the oil in whole plant. Protein content is 7% of the dry matter or 45% of the proteins in whole plant. DSC measurements indicate that denaturation of proteins is almost complete in the cake meal. DMTA spectrum of its milled powder reveals a significant peak at high temperature (between 175 and 200°C). As already observed with industrial sunflower cake meal, it can be associated with the glass transition of proteins. As a mixture of fibres and proteins, the cake meal can be considered as a natural composite. It is successfully processed into biodegradable and value-added agromaterials by thermo-pressing. As for DMTA analysis, the glass transition of proteins in the cake meal is also observed with PVT analysis at around 180°C. It makes easier the choice of the best thermo-pressing conditions to produce panels with higher mechanical properties in bending. These properties increase simultaneously with temperature, pressure and time chosen for molding operation. The highest flexural strength at break (11.5 MPa) and the highest elastic modulus (2.22 GPa) are obtained for the next molding conditions: 200°C and 320 kgf/cm2 during 60 s. Drop angle measurements show that the corresponding panel is also the most resistant to water. No significant transition is observed inside this panel above 0°C and until 200°C with DMTA analysis. Proteins ensure the agromaterial cohesion without any phase change in this temperature range, and fibres entanglement also acts like reinforcement. This panel could be used as inter-layer sheets for pallets or for the manufacturing of biodegradable containers (composters, crates for vegetable gardening) by assembly of panels.

Comparison between two different pretreatment technologies of rice straw fibers prior to fiberboard manufacturing: Twin-screw extrusion and digestion plus defibration

“…Recently, Vandenbossche et al (2016Vandenbossche et al ( , 2015Vandenbossche et al ( , 2014 used the twin-screw extrusion technology for conducting the thermo-mechanical and thermo-chemo-mechanical pretreatment of different lignocellulosic biomass sources, in the case not for the subsequent manufacture of composite materials but for the production of second-generation bioethanol using a biocatalytic action. Evon et al (2015Evon et al ( , 2014Evon et al ( , 2012Evon et al ( , 2010aEvon et al ( , 2010b) also produced self-bonded fiberboards from the cake generated during the biorefinery of sunflower whole plant using a twin-screw extruder. In addition, Theng et al (2015a) prepared a thermo-mechanical pulp from corn biomass by digestion plus defibration to produce binder-free fiberboards.…”

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

“…In conclusion, it was reasonable to suppose that lignocellulosic fibers would act as effective reinforcing fillers inside thermal insulation fiberboards. Moreover, because the cake oil content was higher than in previous studies (Evon et al, 2010a(Evon et al, , 2010b, residual oil in fiberboards would contribute to make them less water-sensitive and also more durable than truly deoiled agromaterials, in spite of their overall hydrophilic character. Figure 2.…”

“…Temperature, pressure and length of time of thermo-pressing all increase fiberboard bending mechanical properties (Evon et al, 2010b(Evon et al, , 2012b, and the highest flexural strength at break (11.5 MPa) and highest elastic modulus (2.2 GPa) are obtained with a cake having a dry matter residual oil content of 14.5%, using the following molding conditions: 500 mg/cm 2 cake quantity, 200 °C temperature for the two heated hydraulic press aluminum plates, 31.4 MPa pressure applied, and 60 s molding time (Evon et al, 2010b). Fiberboard thickness is just 3.9 mm with quite a high density (1035 kg/m 3 ).…”

“…Because the cake is a mixture of proteins and lignocellulosic fibers, it has been the subject of new valorizations. It can be thought of as a natural composite meaning that it can be processed by thermo-pressing into natural, cohesive, and value-added fiberboards, with the proteins acting as internal binder, and lignocellulosic fibers as reinforcing fillers (Evon et al, 2010a(Evon et al, , 2010b(Evon et al, , 2012a(Evon et al, , 2012b(Evon et al, , 2012c(Evon et al, , 2015.…”

New Renewable and Biodegradable Fiberboards from a Coriander Press Cake

“…The press cakes could further be incorporated into biodegradable polymers, such as polycaprolactone and poly(lactic acid), thus acting as reinforcing fillers for the biocomposite industry [27,28]. Finally, as renewable resources containing both proteins and fibers, the press cakes could be considered as natural composites, thus being usable for the production of biodegradable and value-added agromaterials through thermopressing [29][30][31][32][33][34][35][36].…”