Tensile tests of kenaf fiber with different characteristics were carried out and their potential application to the reinforcement of FRP was conducted. Specifically, the effect of stem diameter and length on the mechanical properties of kenaf fiber of different types was investigated. In addition, after converting kenaf fibers into pulp, the cellulose content ratios and extent of polymerization within the fibers were measured to investigate their influence on the tensile strength of the fibers. The tensile strength of kenaf fiber was observed to increase with the length of the stem. Moreover, at approximately 48%, the ratio of cellulose contained in kenaf fiber was found to be stable regardless of the length and diameter of the kenaf stem. Cellulose DP in kenaf fibers was observed to change depending on the tensile strength of the fiber and longer kenaf fibers were found to have relatively higher tensile strengths and cellulose DP.
The elastic properties of alkaline earth oxides (AEOs) under high temperature are discussed within the framework of many body Lundqvist potential incorporating the contribution of thermal phonon pressure. The short-range repulsive interaction is taken up to the second nearest neighbors. The derived expressions are used to compute the values of second-order elastic constants (SOECs) and bulk modulus of alkaline earth oxides at different temperatures (300 ° K–2000 ° K). The results are found to be satisfactory and are in agreement with available experimental and the theoretical results.
This paper proposes the development and structural characterisation of an Er 3 + / Yb 3 + doped hybrid organic-inorganic material synthesised by a nonhydrolytic sol-gel process. By using a pumping laser diode at 980 nm, a typical Er 3 + luminescence has been recorded in the near infrared region (1.53–1.55 μ m). However, the detected fluorescence was particularly weak compared to that generally observed in pure mineral materials, suggesting the occurrence of strong quenching due to multiphonon relaxation processes. To understand this behaviour, structural characterisation of both of the matrix and the local environment of Er 3 + ions were conducted employing infrared spectroscopy, nuclear magnetic resonance, electron paramagnetic resonance, and neutron scattering. These studies showed that the major phenomenon competing with the Er 3 + fluorescence is intimately associated to the strong vibrational modes of the organic species that involve multiphonon relaxation processes, resulting in energy dissipation within the host matrix.
