Estudo do comportamento tribológico de materiais compósitos à base de titânio reforçado com partículas cerâmicas para aplicação em implantes articulares

Dissertação de mestrado integrado em Engenharia Biomédica

Novel auxetic structures from basalt braided composites for structural applications

Auxetic materials are a class of materials behaves unusual way compared to regular materials i.e. possess negative Poisson’s ratio. This paper reports, the development of auxetic structures based on re-entrant hexagon design from braided composite materials and testing of the mechanical properties (tensile property, auxetic property and work of rupture). The structure developed from glass and basalt braided composite rods and properties were compared between them. Later, the basic re-entrant hexagon design was modified with vertical straight rods to improve their mechanical behavior and their auxetic property was studied. Auxetic behavior of these structures was studied in a tensile testing machine taking video during testing by Digital camera, later the video converted into images to measure the strain values using simple software, ImageJ. Along with experimental work, analytical model was used to calculate the Poisson’s ratio of basic structure and results were compared

Biomimetic strategies to engineer mineralised human tissues

In the last few years, many reports have been describing promising biocompatible and biodegradable materials that can mimic in a certain extent the multidimensional hierarchical structure of bone, while are also capable of releasing bioactive agents or drugs in a controlled manner. Despite these great advances, new developments in the design and fabrication technologies are required to address the need to engineer suitable biomimetic materials in order tune cells functions, i.e. enhance cell-biomaterial interactions, and promote cell adhesion, proliferation, and differentiation ability. Scaffolds, hydrogels, fibres and composite materials are the most commonly used as biomimetics for bone tissue engineering. Dynamic systems such as bioreactors have also been attracting great deal of attention as it allows developing a wide range of novel in vitro strategies for the homogeneous coating of scaffolds and prosthesis with ceramics, and production of biomimetic constructs, prior its implantation in the body. Herein, it is overviewed the biomimetic strategies for bone tissue engineering, recent developments and future trends. Conventional and more recent processing methodologies are also described.

Processamento e caracterização de compósitos de Ti-HAP para aplicações biomédicas

Dissertação de mestrado integrado em Engenharia de Materiais

Optimization of magnetoelectric composites based on electroactive polymers for energy harvesting and sensor application

Tese de Doutoramento em Engenharia de Materiais.

Materiais compósitos com incorporação de cânhamo industrial

Projeto de Investigação integrado de mestrado Internacional em Sustentabilidade do Ambiente Construído

Desenvolvimento de um sistema fibroso multicamada para reabilitação de edifícios

Dissertação de mestrado Internacional em Sustentabilidade do Ambiente Construído

Varões entrançados de material compósito com capacidade de monitorização

Dissertação de mestrado integrado em Engenharia Civil

Comportamento de lajes de betão armado pré-fendilhadas e reforçadas à flexão com laminados de CFRP inseridos pré-tensionados

Dissertação de mestrado integrado em Engenharia Civil

Desenvolvimento de materiais auxéticos para aplicações estruturais

Dissertação de mestrado integrado em Engenharia Civil

Efeito do carregamento cíclico e da pré-fendilhação do betão no comportamento de lajes de betão armado reforçadas à flexão com laminados de CFRP inseridos

Dissertação de mestrado integrado em Engenharia Civil

Reforço à flexão de lajes de betão armado com laminados de CFRP pré-esforçados

Dissertação de mestrado integrado em Engenharia Civil (área de especialização em Estruturas e Geotecnia)

Bacterial cellulose-lactoferrin as an antimicrobial edible packaging

Bacterial cellulose (BC) films from two distinct sources (obtained by static culture with Gluconacetobacter xylinus ATCC 53582 (BC1) and from a commercial source (BC2)) were modified by bovine lactoferrin (bLF) adsorption. The functionalized films (BC+bLF) were assessed as edible antimicrobial packaging, for use in direct contact with highly perishable foods, specifically fresh sausage as a model of meat products. BC+bLF films and sausage casings were characterized regarding their water vapour permeability (WVP), mechanical properties, and bactericidal efficiency against two food pathogens, Escherichia coli and Staphylococcus aureus. Considering their edibility, an in vitro gastrointestinal tract model was used to study the changes occurring in the BC films during passage through the gastrointestinal tract. Moreover, the cytotoxicity of the BC films against 3T3 mouse embryo fibroblasts was evaluated. BC1 and BC2 showed equivalent density, WVP and maximum tensile strength. The percentage of bactericidal efficiency of BC1 and BC2 with adsorbed bLF (BC1+bLF and BC2+bLF, respectively) in the standalone films and in inoculated fresh sausages, was similar against E. coli (mean reduction 69 % in the films per se versus 94 % in the sausages) and S. aureus (mean reduction 97 % in the films per se versus 36 % in the case sausages). Moreover, the BC1+bLF and BC2+bLF films significantly hindered the specific growth rate of both bacteria. Finally, no relevant cytotoxicity against 3T3 fibroblasts was found for the films before and after the simulated digestion. BC films with adsorbed bLF may constitute an approach in the development of bio-based edible antimicrobial packaging systems.

Anàlisi paramètrica de l'assaig a compressió d'un panell de material compost rigiditzat amb tres nervis

L’objectiu d’aquest treball és desenvolupar una metodologia per realitzar l’anàlisiparamètrica de l’assaig de compressió d’un panell de material compost rigiditzat ambtres nervis. En primer lloc és necessari desenvolupar un sistema automatitzat per generar i avaluar el conjunt de parametritzacions. A continuació, s’estudiaran quines variables d’estat són les més adequades per representar el vinclament local, la flexió global, la càrrega crítica de desestabilització i l’índex de fallada en l’anàlisi paramètrica. La modelització amb el mètode dels elements finits serveix per simular l’assaig a compressió del panell. La simulació es realitza mitjançant un càlcul no lineal, per estudiar la desestabilització i els fenòmens no lineals que pateix el panell. L’estudi es complementa amb una anàlisi modal i una anàlisi lineal

Acoustic properties of polypropylene composites reinforced with stone groundwood

Currently, acoustic isolation is one of the problems raised with building construction in Spain. The publication of the Basic Document for the protection against noise of the Technical Building Code has increased the demand of comfort for citizens. This has created the need to seek new composite materials that meet the new required acoustical building codes. In this paper we report the results of the newly developed composites that are able to improve the acoustic isolation of airborne noise. These composites were prepared from polypropylene (PP) reinforced with mechanical pulp fibers from softwood (Pinus radiata). Mechanical and acoustical properties of the composites from mechanical pulp (MP) and polypropylene (PP) have been investigated and compared to fiberglass (FG) composites. MP composites had lower tensile properties compared with FG composites, although these properties can be improved by incorporation of a coupling agent. The results of acoustical properties of MP composites were reported and compared with the conventional composites based on fiberglass and gypsum plasterboards. Finally, we suggest the application of MP composites as a light-weight building material to reduce acoustic transmitions