Thermal and thermomechanical behavior of Moroccan Boufeggous variety date seeds Hafsa El Abbari 1 • Sarah Bentahar 1 • Maryam El Marouani 2 • Mhamed Taibi 3 • Abdelouahab Zeriouh 4 • Saloua Sebbahi 2 • Fatima Kifani-Sahban 1 Received: 24 April 2018 / Accepted: 1 February 2019 Ó Akade ´miai Kiado ´, Budapest, Hungary 2019 Abstract In this work, the physicochemical and thermomechanical characteristics of date seeds were examined during their pyrolysis under inert atmosphere from room temperature to 600 °C. We first discuss the thermal analysis characterization including TG/DTG, DTA, and DSC analyses and then the thermomechanical aspects related to fixed bed heat treatments, dimen- sional variations measurements, and SEM characterizations. TG allowed us to delimit the different zones of the pyrolysis of date seeds. Thus, an active pyrolysis zone between 120 and 410 °C is related hemicelluloses decomposition, followed by the degradation of cellulose. Lignin decomposes slowly throughout all the temperature range. All these degradations and reactions are suggested by the different peaks of the mass loss derivative. The DTA and DSC analyses indicate that the thermal stress of date seeds is exothermic. This exothermicity is related to the internal frictions representative of the thermomechanical behavior of the thermally stressed material. Dimensional variation measurements show that the material generally shrinks with slight increases in volume. These phenomena are well evidenced by the characterization by SEM indicating the development of a plastic phase by crazing and shear mainly in volume and the formation of cracks on surface. The development of this phase occurred mainly during the first warming of the material by DSC. Keywords Date seeds (DS) Á TG Á DTA Á DSC Á Dimensional variations (DV) Á Plastic phase Introduction Date, fruit of date palm, is one of the main agricultural products in the Moroccan Sahara regions. Dates and derivative products are an important source of income for aboriginal people and contribute to the economic devel- opment of these regions [1]. Under the Morocco Green Plan launched in recent years, date palms have benefited from subsidies for rehabilitation and densification of existing palms and the creation of new modern plantations [2]. This plan has led to an increase in the production of dates. Thus, the annual production is of around 111,000 tons, which ranks Morocco the 4th in Maghreb countries and the 11th in the world. Note that the regions of Ouarzazate and Errachidia alone contribute about 90% of the national production of dates. Therefore, the production of dates is increasing and waste associated to the packaging and production of pulp and dates juice, especially date seeds are also [2]. Such by-products are of significant economic interest that is why their valuation is important. Usually, date seeds serve as feed for livestock [3], and it is only recently together with the development of date palm plantations that the valuation of date seeds in coffee and cosmetics products has emerged [3, 4]. Date seeds contain & Maryam El Marouani maryam.elmarouani@gmail.com 1 Team of Modeling and Simulation in Mechanics and Energetic, Physical Department, Faculty of Sciences, Mohamed V University, Av Ibn Battouta, B.P. 1014, Rabat 10000, Morocco 2 Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Water and Environment (LS3MN2E- CERNE2D), Department of Chemistry, Faculty of Sciences, Mohamed V University, Av Ibn Battouta, B.P. 1014, Rabat 10000, Morocco 3 Laboratory of Physico-Chemistry of Inorganic and Organic Materials, Mohammed V University in Rabat, ENS Takaddoum, Rabat, Morocco 4 Royal Naval School, Casablanca, Morocco 123 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-019-08060-8