Djibril Diedhiou^{1, 2,}, Mamadou Faye^{3, 4}, Moussa Bagha Diedhiou³, Laure Candy⁴, Virginie Buthod-Cuam⁴, Oumar Sock³, Luc Rigal⁴

The raffinate obtained after fractionating neem seeds in a Clextral BC 21 twin-screw extruder is used as a base for manufacturing an agromaterial by thermo-pressing. Its composition and characteristics have been determined in order to assess its suitability for providing a coherent material. The manufacturing conditions for this agricultural material have been studied using a design of experiments (Doehlert matrix) in order to optimize the parameters in the temperature range between 180 and 200°C and the pressure range between 60 and 300 kg/cm². Increasing the duration of hot pressing increases the rigidity and densification of the material. Thermogravimetric analysis of the agromaterial shows that its constituents are not degraded by temperature during shaping. Dynamic mechanical analysis (DMA) of the material highlighted the rigidity of the agromaterial obtained (elastic modulus between 1500 and 2300 MPa). However, the flexural strength results (nearly 0.5 MPa) reveal that these materials are fragile. The comparison of water adsorption isotherms shows that the thermo-pressed agromaterial is less hygroscopic than the raffinate and can be stored at up to 90% relative humidity without risk of degradation by microorganisms. The azadirachtin content of the material (between 10.58 mg/kg DM and 13.14 mg/kg DM) could give it the advantage of providing protection against insect attacks.

manufacturing, agromaterial, raffinate, twin-screw extrusion, neem seeds, thermo-pressing