Browsing by Author "Ansbert, Clemence"

Now showing 1 - 3 of 3

High energy density materials based on fluorinated bridged trinitromethyl azo triazole derivatives: a quantum chemical study of thermodynamic and energetic properties
(NM-AIST, 2021-03) Ansbert, Clemence
High energy density materials (HEDM) have gained extensive attention due to their energetic properties and safety issues. Nitro and fluoro groups, among others, have become viable substituents in the HEDM triazole framework because of their particular contribution to detonation properties and moderate sensitivity. In this study, fluorinated bis(trinitromethyl) azo triazoles were designed theoretically using the Density Function Theory (DFT) approach with hybrid functional B3LYP. The molecular structures, thermodynamic properties of gaseous species (e.g., enthalpies of detonation and enthalpies of formation) and energetic properties of solid materials (detonation heat Q, pressure PD and velocity VD) have been investigated. The best characteristics attained for the designed azo fluorinated solid compounds are as follows: Q 1650 – 1690 cal g –1 , PD 44 – 46 GPa and VD 9.8 km s –1 . These characteristics are superior to those of conventional explosives, indicating that fluorinated bis(trinitromethyl) azo triazoles are promising HEDM.
High energy density materials based on fluorinated bridged trinitromethyl azo triazole derivatives: a quantum chemical study of thermodynamic and energetic properties
(Springer Nature Switzerland AG., 2020-10-19) Ansbert, Clemence; Pogrebnoi, Alexander M.; Pogrebnaya, Tatiana P.
High energy density materials (HEDM) have gained extensive attention due to their energetic properties and safety issues. Nitro and fluoro groups, among others, have become viable substituents on the triazole framework because of their particular contribution to detonation properties and moderate sensitivity. In this study, Density Function Theory (DFT) approach was employed to design fluorinated bis(trinitromethyl) azo triazoles. The molecular structures, thermodynamic properties of gaseous species (e.g., enthalpies of detonation and enthalpies of formation) and energetic properties of solid materials (detonation heat Q, pressure PD and velocity VD) have been investigated. The best characteristics attained for the designed azo fluorinated solid compounds are as follows: Q 1650–1690 cal g−1, PD 44–46 GPa and VD 9.8 km s−1. These characteristics are superior to those of conventional explosives, indicating that fluorinated bis(trinitromethyl) azo triazoles are promising HEDM.
Reinforcement efficiency of sisal fibers in composites for structural applications
(Elsevier, 2025-10-15) Ansbert, Clemence; Machunda, Revocatus; Madsen, Bo
Composites made up of natural fibres in a polymer matrix have gained extensive attention due to their environmentally sustainability and good mechanical properties. This is a fundamental study of sisal technical fibres and their reinforcement efficiency. Sisal technical fibres from three harvest times groups have been used for manufacturing of composites with aligned fibres and varying volumetric composition. Based on microscopy of composite cross-sections, the sisal technical fibres were found to consist of about 50 – 200 single fibres with cross-sectional area of 143 ± 57 µm2 and lumen content of 23 ± 9 %. The polymer matrix was found to be able to flow into the lumen of the single fibres, resulting in composites with a relative low porosity content. The volumetric composition of the composites is found to be well predicted using the established fibre and matrix correlated porosity factors. Stiffness and failure stress of the composites were measured in the ranges 6 – 15 GPa and 80 – 220 MPa, respectively. By using micromechanical models, the reinforcement efficiency of the sisal technical fibres was found to be the same for the three harvest times groups, with an overall fibre stiffness of 56 GPa. Based on the used models, stiffness and specific stiffness of the sisal fibre composites were compared with other fibre composites. The predicted maximum specific stiffness of 3.4 GPa0.5 g−1 cm3 for the sisal fibre composites is comparable to other fibre composites, which shows the good potential for using sisal fibres in composites for structural applications.