Fatigue in sisal fiber reinforced polyester composites:Hysteresis and energy dissipation

AbstractNatural fibre reinforced polymer biocomposites (NFPBCs) constitute an important branch in the field of green composite materials. The work describes the fatigue behaviour of polyester biocomposites reinforced with natural sisal fibres and stacked as cross laminates with [0/90]s sequence Three-point bending static and cyclic tests have been used to investigate the fatigue behaviour of these particular bio-reinforced composites. The cyclic tests have been carried out at 1.5Hz of frequency using a sinusoidal waveform and loading levels varying between rd = 0.55 to 0.95 and the curves of stiffness degradation (F/F0) has been plotted. Failure is reached after the first few cycles for high loading levels, whereas for low values of rd (0.55) fracture is only partial, even after reaching one million of cycles

Non-isothermal crystallization kinetics and nucleation behavior of isotactic polypropylene composites with micro-talc

cited By 1The non-isothermal crystallization (NIC) of isotactic polypropylene (iPP) and its composites with submicronic talc particles (μ-talc) was investigated by differential scanning calorimetry. The modeling of the NIC kinetics of the iPP matrix was performed using Jeziorny-modified Avrami’s model, Ozawa’s and Mo’s theoretical approaches. The Jeziorny’s and Ozawa’s theories allowed us to confirm that the μ-talc filler particles significantly promote the NIC kinetics of the iPP matrix which noticeably manifests itself via a change in the nucleation mechanism. However, Mo’s model proved to be the more relevant model to account for the NIC of the present materials. In parallel, the activation energy and nucleation activity of NIC were calculated by Kissinger’s and Dobreva’s methods, respectively. Both approaches reveal that a maximum nucleation activity of μ-talc takes place for 20% filler content. This finding is discussed in relation to the μ-talc content thresholds of mechanical percolation and crystallinity saturation that were reported in previous studies for these composites, about 10 and 30% μ-talc, respectively. An endeavor of physical explanation for these phenomena is put forward. © 2019, Akadémiai Kiadó, Budapest, Hungary

A Statistical Analysis of Size, Shape and Tensile Properties of Fibres Extracted from Date Palm (Phoenix Dactylifera L.) Rachis

Algeria is the largest country in Africa by in terms of land area, which makes it contain large quantities of agricultural residues. The aim of this study is the valorisation of the huge amount of agricultural residue of date palm rachis available in Algeria to be used as reinforcement in bio-composite materials for various industrial applications. The analysis of the morphology of the of the date palm rachis cross-section allowed us to identify two main types of fibres according to their microstructure: vascular bundles and fibre strands. The chemical and molecular structure analysis of the date palm rachis fibres was examined by Fourier transform infrared spectroscopy (FTIR). The tensile properties of the fibre extracted were investigated under tensile loading test. The experimental results obtained for the tensile strength, Young’s modulus and strain at break of the fibres have been analysed, because of their dispersion, using three-parameter and two-parameter Weibull statistical laws. The tensile strength and Young’s modulus of the fibre strand were found to be about than four times higher than for the vascular bundle and their predicted model was determined. The tensile properties obtained for the investigated fibre were compared with other lignocelluloses fibres, existing in the literature, and it shows its great potential for use as reinforcement in bio-composite materials