Tony Pereira

Surface functionalized alumina nanoparticle filled polymeric nanocomposites with enhanced mechanical properties

Alumina nanoparticles were successfully functionalized with a bi-functional coupling agent, (3-methacryloxypropyl)trimethoxysilane (MPS), through a facile neutral solvent method. MPS was found to be covalently bound with the nanoparticles. The linked MPS was polymerized with a vinyl-ester resin monomer through a free radical polymerization. Atomic force microscope phase images showed a uniform distribution of nanoparticles. Microtensile test results revealed the Youngs modulus and strength increasing with particle loading. Microscopic examinations revealed the presence of large plastic deformations at the micron scale in the nanocomposites in agreement with the observed strengthening effect of functionalized nanoparticles. Thermo-gravimetric analysis (TGA) did not show any significant change in the thermal degradation of the nanocomposite as compared with the neat resin. The polymer matrix effectively protected the alumina nanoparticles from dissolution in basic and acidic solutions.

Particle surface engineering effect on the mechanical, optical and photoluminescent properties of ZnO/vinyl-ester resin nanocomposites

Zinc oxide (ZnO) nanoparticles functionalized with a bi-functional coupling agent methacryloxypropyl-trimethoxysilane (MPS) were used to fabricate a vinyl-ester resin polymeric nanocomposite, which shows an improved interfacial interaction between the particle and matrix. As a result, in comparison to the unmodified particle-filled nanocomposites, the functionalized particle-filled composites possessed higher resistance to thermal degradation, and demonstrated improved UV shielding and enhanced photoluminescent properties. The more uniform particle dispersion, passivation of the particle surface with MPS and increased oxygen vacancies were justified to contribute to the increased thermal stability and the enhanced photoluminescent properties. Significant tensile strength improvement was closely related to the observed uniform particle distribution and the intimate interfacial interaction through the strong chemical bonding.

Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer?particle interactions.

Energy Storage Structural Composites: a Review

This study demonstrates the construction of a multifunctional composite structure capable of energy storage in addition to load bearing. These structures were assembled and integrated within the confines of a multifunctional structural composite in order to save weight and space. Carbon fiber reinforced plastic (CFRP) composites were laminated with energy storage all-solid-state thin-film lithium cells. The processes of physically embedding all-solid-state thin-film lithium energy cells into carbon fiber reinforced plastics (CFRPs) and the approaches used are reviewed. The effects of uniaxial tensile loading on the embedded structure are investigated. The mechanical, electrical, and physical aspects of energy harvesting and storage devices incorporated into composite structures are discussed. Embedding all-solid-state thin-film lithium energy cells into CFRPs did not significantly alter the CFRP mechanical properties (yield strength and Youngs modulus). The CFRP embedded energy cells performed at baseline charge/discharge levels up to a loading of about 50% of the ultimate CFRP uniaxial tensile rupture loading.

The performance of thin-film Li-ion batteries under flexural deflection

A method is introduced to study the effects of flexural deformation on the electrical performance of thin-film lithium-ion batteries. Flexural deformation of thin films is of interest to engineers for applications that can be effective in conformal spaces in conjunction with multi-functional composite laminates in structural members under mechanical deflections such as thin airfoils used in unmanned aerial vehicles (UAVs). A test fixture was designed and built using rapid prototyping techniques. A baseline reference charge/discharge cycle was initially obtained with the device in its un-flexed state, in order to later contrast the performance of the thin-film battery when subjected to deflections. Progressively larger deflections were introduced to the device starting with its un-deformed state. The cord flexure was applied in increments of 1.3% flex ratio, up to a maximum of 7.9%. At each successive increment, a complete charge/discharge cycle was performed. Up to a flex ratio of 1.3%, no effects of mechanical flexure on battery performance were observed, and the device performed reliably and predictably. Failure occurred at deflections above 1.3% flex ratio.

The transition to a sustainable society: a new social contract

This paper explores issues that are central to ecological economics. In spite of a substantial body of research and other literature that has appeared in recent decades on transition, and countless other efforts, no progress has been made to halt the increase in global warming, global emissions, rampant population growth, or several hundred other critical planet sustainability indicators including global species extinction. The opposite is true. Consumption has escalated and it is poised to double and, with it, planetary decay has followed closely. The aim of this work is to introduce a pragmatic solution and the economics mechanisms solidly rooted in science, in the laws of conservation of mass and energy, and in environmental and ecological sustainability that are necessary to overcome the tremendous forces of social, political, and economic resistance to major change. To advance towards a sustainable civilization, adopting a holistic approach with those underlying principles in all aspects of human activity, among others economy, finance, industry, commerce, engineering, politics, architecture, and education, is both lacking and fundamentally required. A short review of the state-of-the-art of the science on the critical status of the planet’s resources and its life-supporting systems is presented, as well as a brief catalog of the seminal works of the science that gave rise to its metrics and established early on the groundwork for the understanding of the degree of sustainability of the planet. We present the argument why past and current schemes of human economics, organization, culture, and politics cannot achieve anything else, but complete and utter failure under their own underlying precepts. A rigorous and disciplined process on how to overcome and avoid the precipitous decline and collapse of the environmental and planetary biosystems on which all life depends, including human life, and a new view towards the world and the universe we all have no choice but to live in, are also offered.

Flexible Dye-Sensitized Nano-Porous Films Solar Cells

This chapter reviewed the progress in the flexible dye-sensitized nanostructured thin film solar cells (DSSCs). Flexible DSSCs show potential to be commercialized in the field of DSSCs. It attracts many efforts to study on it in recent years. So in this chapter, we reviewed the flexible DSSCs and their current status. Further reviewed on the low temperature preparation of the nanostructured thin film methods and technology, which is the key point for the flexible DSSCs. Moreover, electron transport and back reaction at the TiO2 / electrolyte interface, interfacial electron transfer, charge separation and recombination also has been reviewed, which would help to go insight into the essential of the flexible DSSCs. The further improvement of the conversion efficiency of the flexible DSSCs has been discussed, and outlook was presented based on the review study.