Monitoring the early stiffness development in epoxy adhesives for structural strengthening

The present work aimed to assess the early-age evolution of E-modulus of epoxy adhesives used for Fibre-Reinforced Polymer (FRP) strengthening applications. The study involved adapting an existing technique devised for continuous monitoring of concrete stiffness since casting, called EMM-ARM (Elasticity Modulus Measurement through Ambient Response Method) for evaluation of epoxy stiffness. Furthermore, monotonic tensile tests according to ISO standards and cyclic tensile tests were carried out at several ages. A comparison between the obtained results was performed in order to better understand the performance of the several techniques in the assessment of stiffness of epoxy resins. When compared to the other methodologies, the method for calculation of E-modulus recommended by ISO standard led to lower values, since in the considered strain interval, the adhesive had a non-linear stress–strain relationship. The EMM-ARM technique revealed its capability in clearly identifying the hardening kinetics of epoxy adhesives, measuring the material stiffness growth during the entire curing period. At very early ages the values of Young׳s modulus obtained with quasi-static tests were lower than the values collected by EMM-ARM, due to the fact that epoxy resin exhibited a significant visco-elastic behaviour.

Development of innovative hybrid sandwich panel slabs: Experimental results

The authors appreciate the collaboration of the following labs: Civitest for developing DHCC materials, PIEP for conducting VARTM process (Eng. Luis Oliveira) and Department of Civil Engineering of Minho University to perform the tests (Mr. Antonio Matos and Eng. Marco Jorge).

The impact of PBL on transferable skills development in management education

Attention to transferable skills is growing in higher education. Problem-based learning (PBL) is increasingly used in management education for its promising potential to, amongst others, promote transferable skills, including problem-solving, critical thinking and teamwork skills. However, this relationship is seldom assessed. In this study, I use structural equation modelling to examine the effectiveness of PBL, measured through students’ perceptions of satisfaction and skills development. Results show the development of transferable skills is explained by interaction with tutors and a host company, and defining teamwork rules. Satisfaction is explained by skills development, assessment issues, defining teamwork rules and understanding how organisations work. I draw conclusions and recommendations.

Development of bioplastics from agro-wastes

Poster

Development of hyaluronic acid, dextrin and extracellular matrix hydrogels for cell expansion

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)

Development of auxetic structures from braided composites produced from basalt fiber

In this work, novel auxetic structure has been developed from braided composites produced from basalt fiber. The paper reported the auxetic and tensile behavior of the structures produced from basalt fiber and also compared with structures developed from braided composites having glass fiber as core. The basic design is modified with straight rod to improve the strengthening behavior of structure with structural elements. The Poisson’s ratio of the modified structure are studied. The Poisson’s ratio of the structure made from basalt and glass reinforced BCRs are almost similar but the tensile behavior of basalt based structure is good than glass fiber.

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

Development of hybrid composite plate (HCP) for strengthening and repair of RC structures

Tese de Doutoramento em Engenharia Civil

Development of composite auxetic structures for civil engineering applications

Tese de Doutoramento em Engenharia Têxtil

Development of a water-in-oil-in-water multiple emulsion system integrating biomimetic aqueous-core lipid nanodroplets for protein entity stabilization. Part I: experimental factorial design

Lipid nanoballoons integrating multiple emulsions of the type water-in-oil-in-water enclose, at least in theory, a biomimetic aqueous-core suitable for housing hydrophilic biomolecules such as proteins, peptides and bacteriophage particles. The research effort entertained in this paper reports a full statistical 23x31 factorial design study (three variables at two levels and one variable at three levels) to optimize biomimetic aqueous-core lipid nanoballoons for housing hydrophilic protein entities. The concentrations of protein, lipophilic and hydrophilic emulsifiers, and homogenization speed were set as the four independent variables, whereas the mean particle hydrodynamic size (HS), zeta potential (ZP) and polydispersity index (PI) were set as the dependent variables. The V23x31 factorial design constructed led to optimization of the higher (+1) and lower (-1) levels, with triplicate testing for the central (0) level, thus producing thirty three experiments and leading to selection of the optimized processing parameters as 0.015% (w/w) protein entity, 0.75% (w/w) lipophilic emulsifier (soybean lecithin) and 0.50% (w/w) hydrophilic emulsifier (poloxamer 188). In the present research effort, statistical optimization and production of protein derivatives encompassing full stabilization of their three-dimensional structure, has been attempted via housing said molecular entities within biomimetic aqueous-core lipid nanoballoons integrating a multiple (W/O/W) emulsion.