The electrical sensitivity of glass fiber/multiwall carbon nanotube/vinyl ester hierarchical composites containing a tailored electrically-percolated network to self-sense accumulation of structural damage when subjected to cyclic tensile loading-unloading is investigated. The hierarchical composites were designed to contain two architectures differentiated by the location of the multiwall carbon nanotubes (MWCNTs), viz. MWCNTs deposited on the fibers and MWCNTs dispersed within the matrix. The changes in electrical resistance of the hierarchical composites are associated to their structural damage and correlated to acoustic emissions. The results show that such tailored hierarchical composites are able to self-sense damage onset and accumulation upon tensile loading-unloading cycles by means of their electrical response, and that the electrical response depends on the MWCNT location.

In order to predict the mechanical behavior of a composite during its service life, it is important to evaluate itsmechanical response under different types of external stresses by studying the initiation and development of cracksand the effects induced by damage and degradation. The onset of damage is related to the structural integrity of thecomponent and its fatigue life. For this, among other reasons, non-destructive techniques such as acoustic emission(AE) have been widely used nowadays for composite materials characterization. This method has demonstratedexcellent results on detecting and identifying initiations sites, cracking propagation and fracture mechanisms ofpolymer matrix composite and ceramic materials. This paper focuses on commenting the importance of the acousticemission technique as a unique tool for characterizing mechanical parameters in response to external stresses anddegradation processes by reviewing previous investigations carried out by the author as participant. Acoustic emissionwas employed to monitor the micro-failure mechanisms in composites in relation to the stress level in real-time duringthe tests carried out. Some results obtained from different analysis are discussed to support the significance of usingAE, technique that will be increasingly employed in the composite materials field due to its several alternatives forunderstanding the mechanical behavior; therefore, the objective of this manuscript is to involve the benefits andadvantages of AE in the characterization of materials.

Colok seed (Talisia floresii Standl) represents 80% of the total fruit weight and is obtained from trees that grow mainly in Yucatan Peninsula. The aim of this work was the physicochemical characterization from colok starch seeds as an alternative to conventional sources and to identify its characteristics for potential applications in different industrial sectors. Starch yield was 42.1% with low levels of lipids, ashes and fibers. The amylose content was 33.6 ± 1.15%. The gelatinization temperature was 85 ± 0.25 °C. Color analysis resulted in a starch with an intermediate luminosity, reflecting a dark color. Finally, in morphology, starch granule exhibited an average size of 18.7 μm, spherical, uniform and without fractures. Overall results demonstrated that isolated colok starch can be used in food products that require high processing temperatures, such as sauces, cookies, noodles, bread and food packages.