La revue : Journal of Applied Polymer Science
Domaine : Polymer science
Mots Clés : biodegradable; cellulose and other wood products; fibers; hydrophilic polymers; mechanical properties
Auteur : M Khaldi, M M Bouziane, A Vivet, H Bougherara
Issn : 0021-8995 Eissn : 1097-4628 vol : 137, Num : 137, pp :
Date de publication : 2020-01-17
Résume : Composites reinforced with plant‐based fibers present a high potential for valorization in new industrial applications due to their good specific mechanical characteristics, renewability, and recyclability. In order to accelerate their wide industry adoption, it is critical to assess their behavior and durability in heat and humid environments. This article aims at investigating the effects of temperature and relative humidity (RH) on the longitudinal and transverse mechanical properties of the lignocellulosic fibers extracted from alfa plant (Stipa tenacissima L). For this purpose, tensile and nanoindentation tests were performed on elementary alfa fibers subjected to a thermal cycle of 200°C. The fibers were held at various periods of 15, 30, 60 and 120 min. The test results showed that the longitudinal and transverse Young's moduli are moderately affected by short thermal cycles having duration of 15–30 min. However, for longer thermal cycle (i.e., 2 hr), a degradation of 21% for the transverse modulus was recorded. This degradation doubled for the longitudinal modulus (43 vs. 21%). A similar trend was observed for the breaking strength. This study also showed that the RH strongly affects the mechanical performances of alfa fibers.
Experimental analysis of Implant–cement interfacial behaviour under shear mode loading conditions
La revue : Domaine : Biomatériaux
Mots Clés : Auteur : Bouziane M M, Khaldi M, Serier B, Benseddiq N, Zerdali M, Benbarek S, Bachir Bouiadjra B A
Issn : Eissn : vol : , Num : , pp :
La revue : Journal of Applied Polymer Science
Domaine : Polymer science
Mots Clés : composites; fibers; mechanical properties; resins; surfaces and interfaces
Auteur : M. Khaldi, A. Vivet, A. Bourmaud, Z. Sereir, B. Kada
Issn : 0021-8995 Eissn : 1097-4628 vol : 133, Num : 31, pp :
Date de publication : 2016-04-07
Résume : In this article, we first review state‐of‐the‐art experimental techniques and measurements to characterize the mechanical properties of anisotropic vegetal alfa fibers, epoxy‐resin, and the behavior of the interphase between the matrix and alfa fibers. Second, we conduct experimental tests to determine the mechanical properties of fibers, resin, and the interphase. Third, we carry out a series of finite element simulations to predict damage initiation and to estimate crack propagation in alfa‐fiber/epoxy‐resin (AFER) composites. Different tests to determine the longitudinal Young's modulus of alfa fibers and epoxy resin as well as nanoindentation tests to obtain the transverse stiffness of the fibers are presented. Experimental results from the characterization are introduced in a micromechanical model to estimate, using the concept of the energy release rate (ERR), the matrix crack, and its interaction with interfacial debonding. The wettability problems in the preparation of vegetable composites and their effect on fiber‐matrix interfacial debonding are also addressed. The analysis of the damage behavior of AFER composites demonstrates that under load transverse to the fiber axis, a crack initiated in the matrix is propagated perpendicular to the direction of the load. Near the interface, the ERR decreases and this energy is higher in the presence of interfacial debonding areas generated by problems of fiber wettability.
