Artur Mateus - Academia.edu (original) (raw)

Papers by Artur Mateus

Polymers

Bioplastics are one of the possible alternative solutions to the polymers of petrochemical origin... more Bioplastics are one of the possible alternative solutions to the polymers of petrochemical origins. Bioplastics have several advantages over traditional plastics in terms of low carbon footprint, energy efficiency, biodegradability and versatility. Although they have numerous benefits and are revolutionizing many application fields, they also have several weaknesses, such as brittleness, high-water absorption, low crystallization ability and low thermal degradation temperature. These drawbacks can be a limiting factor that prevents their use in many applications. Nonetheless, reinforcements and plasticizers can be added to bioplastic production as a way to overcome such limitations. Bioplastics materials are not yet studied in depth, but it is with great optimism that their industrial use and market scenarios are increasing; such growth can be a positive driver for more research in this field. National and international investments in the bioplastics industry can also promote the gr...

Materiais 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Polymers

In this study, we describe the design and fabrication of an industrial injection moulding system ... more In this study, we describe the design and fabrication of an industrial injection moulding system that can be mounted and used on the NCD-SWEET small-angle X-ray scattering beamline at ALBA. We show how highly useful time-resolved data can be obtained using this system. We are able to evaluate the fraction of the material in the mould cavity and identify the first material to solidify and how this varies with the injection temperature. The design follows current industrial practice and provides opportunities to collect time-resolved data at several points within the mould cavity so that we can build up a 4D perspective of the morphology and its temporal development. The quantitative data obtained will prove invaluable for the optimisation of the next generation of injection moulding techniques. This preliminary work used results from the injection moulding of a general-purpose isotactic polypropylene.

MATERIAIS 2022

Polymers

Direct digital manufacturing consists of a set of techniques that enable products to be fabricate... more Direct digital manufacturing consists of a set of techniques that enable products to be fabricated directly from their digital definition, without the use of complex tooling or moulds. This manufacturing approach streamlines prototyping and small-scale production, as well as the mass customization of parts with complex designs immediately fixed before fabrication. With broad applicability, there are clearly opportunities in the field of medical devices for its use. However, many of the developments of direct digital manufacturing focus on simply specifying the shape or the form of the product, and this limited scope throws away many of the particular advantages of direct digital manufacturing. This work is focused on remedying this situation so that the digital specification of the fabricated product includes the properties as well as the form of the product. We use in situ time-resolving small-angle X-ray scattering measurements performed at the ALBA Synchrotron Light Source in Bar...

MATERIAIS 2022

Materiais 2022

MATERIAIS 2022

Sustainability and Automation in Smart Constructions, 2020

The plastic injection molding industries is nowadays one of the strongest Portuguese industries a... more The plastic injection molding industries is nowadays one of the strongest Portuguese industries and internationally known for their good quality products. Currently an injection mold is a solid, which is heavy and expensive to produce structure due to the use of conventional subtraction material processes. The need to produce more parts with high quality in a short period of time and at a lower cost requires the continuous development on geometries, materials and manufacturing processes of injection molds. The optimization of mold cooling processing can undoubtedly lead to a reduction of the effective total time of the injection process, enabling a shorter manufacturing time, which leads to a reduction of production costs. Combining the requirements of injection mold production with the advantages of Additive Manufacturing (AM) technologies, the Selective Laser Melting (SLM) emerges as a quicker and sustainable alternative to the construction of these structures. In this work two ty...

This work proposes a new Multi-Material Direct Laser Sintering/Melting additive process (MMDLS/M)... more This work proposes a new Multi-Material Direct Laser Sintering/Melting additive process (MMDLS/M) for the production of Multi Material components with materials gradations Functionally Graded Materials (MMFGMs). An additive layer-by-layer process was used, which is ideal for MMFGMs, since by design, material is only added where is strictly and functionally needed, minimizing waste and enhancing the overall properties of the component being built and theoretically imposes no restriction on the shape being built, being highly customizable, which makes it ideal for applications in many industries such as medical, aeronautical, etc. Moreover, this process encompasses a wider perspective of the global methodology of a component’s production, since the physical phenomena occurring during these processes have a strong impact on the quality of the produced parts, so special focus has been given to the design and manufacturing stages, with a closed-loop control to apply corrections to the de...

Procedia Structural Integrity, 2020

This paper aims at studying the cyclic plastic behaviour of the 7075-T651 aluminium alloy under f... more This paper aims at studying the cyclic plastic behaviour of the 7075-T651 aluminium alloy under fully-reversed strain-controlled conditions. Tests are conducted under strain-control mode, at room temperature, in a conventional servo-hydraulic machine, from smooth samples, using the single step method, with strain amplitudes (/2) in the range ±0.5 to ±2.75%. This material has exhibited a mixed behaviour, i.e. cyclic strain-hardens at higher strain amplitudes (/2/>1.1%) and cyclic strain-softens at lower strain amplitudes (/2<1.1%). A linear relationship between the degree of cyclic strain-hardening and the strain amplitude has been established for higher strain amplitudes. Fatigue-ductility and fatigue-strength properties agree with those found in the open literature for the same loading conditions.

Procedia Manufacturing, 2017

In this paper an integrated methodology for implants personalized manufacturing is presented. Thi... more In this paper an integrated methodology for implants personalized manufacturing is presented. This methodology materializes the hybrid material implants manufacturing through the integration of two or more advanced Additive Manufacturing (AM) technologies. Furthermore, high strength biomechanical implants with optimized geometry and mass can be manufactured by biomimetic concepts application. The combination of polymers and ceramics or polymers and metal materials (or metal alloys) allows a significant leap in the development and production of a great diversity of components and applications. The combination of advanced additive manufacturing processes, e.g. the Selective Laser Melting (SLM) or Selective Laser Sintering (SLS) and the StereoLithography (SL), make possible the production of parts with almost unlimited geometric freedom and custom multimaterial. The manufacturing flexibility and the processing capacity of the different combinations of materialsmetal/polymer-obtained from hybrid additive manufacturing systems-SLM/SL-are demonstrated here by the manufacture of a dental bridge implant.

The growing of national and international competition, forces the companies to opt for new techno... more The growing of national and international competition, forces the companies to opt for new technologies, aiming at obtaining competitive, higher quality and precision products with reduced lead time to market. Rapid Prototyping and Tooling (RPT) are important technologies used for short series of products with tight specifications. Simultaneously with these techniques, it is possible to use Reaction Injection Moulding (RIM). Due to the low pressures involved, RIM allows for the production of high quality prototypes moulded in moulds made from various materials. The use of RIM together with RPT allows for the production of high quality and complex prototypes at even lower cost. RIM products are used by the automobile and medical industries. In this study the characterization of the performance of products produced by RIM is done, using moulds in several materials (aluminum, silicone and resin with graphite) and polyurethane (PUR) reactants in various percentages. The use of materials with different thermal properties affects the PUR curing process, which influence the morphology and mechanical properties of the mouldings. Introduction The reaction injection moulding (RIM) is a process for the rapid production of complex plastic parts mostly in polyurethane systems (PUR) [1]. In RIM, the mixture and the chemical reaction of the liquid isocyanate and polyol components originate the polyurethane. The mixture of the two components is done just before injection into the mould. The polyol determines the physical characteristics of the PUR including density, impact strength, flexural modulus and colour of the moulded part [2]. Inside the mould, the liquid undergoes an exothermic chemical reaction, which forms the polyurethane polymer in the mould. The polymerisation or curing occurs in the mould, at relatively low temperature and pressure [3]. The shot and cycle times vary, depending on the part size and the PUR system used [4]. With the RIM process less expensive moulds, less energy, and lower-tonnage presses are required in comparison with thermoplastic processing [5]. These characteristics provide design, economic and processing flexibility [6]. When RIM is associated with RPT technologies for making the moulds these display lower structural rigidity and thermal conductivity [7]. The use of moulds in materials different from steel, for example, PUR, epoxy resin with fillers or silicone, leads to the cost, and allows for rapid geometry modifications whenever required. Furthermore, these moulds are sufficiently strong to support the injection pressures during the process. However the low thermal conductivity of this material will originate an increase of temperature in cavity of mould and consequently affect curing process. The choice of material for a RIM tool depends on several factors, such as: number of cavities, required superficial quality, production run and the need to accomplish subsequent alterations [8]. The adequate selection of the manufacturing process for making moulds depends on the complexity of the part and its tolerance, the number of parts to produce and the material to be used [9].For the fabrication of the moulds, aluminum, resin with graphite and polyurethanes with deferent density were used. Because of their hardness and mechanical strength, special aluminum alloys, either cast of forged, are suitable for prototype moulds [8]. Aluminum moulds show advantages in terms of weight, heat transfer and low production cost. Aluminum moulds can produce between 5 000 and 50 000 plastic parts [9]. RPT subtractive processes can be used to produce polyurethane moulds for RIM. PUR block materials have good machinability, their manufacturing time is short and the cost is low. The major drawback is the low thermal conductivity leading to longer moulding cycles. The epoxy resins possess important characteristics, such as, dimensional stability even at high temperatures, they are easy to process and they possess a low contraction .The epoxy moulds are normally used in prototype series. Their main limitations are brittleness, the surface finish and low heat transfer [9].When epoxy moulds are used, the chemistry of the PUR systems must be adjusted to slow down the polymerization reaction [5]. In this study the influence of the thermal conductivity of the mould in the cure process and in the mechanical properties was studied. A moulded part was produced in moulds made from several materials: aluminum, two PUR and graphite filled epoxy. Experimental Mould materials. The following materials were used to manufacture and respective thermal conductivity are represented in the table 1. Mould material Lab 850 Prolab 65 Resin with graphite Alumec 89 Thermal conductivity(W/mK) 0.2 0.2 100 165 Table 1: material for moulds and respective thermal conductivity RIM. For the production of the mouldings a resin RIM876900 (from Axson) and RIM machine (Dopag EconoMIx Compact) as used. The following processing conditions were…

Proceedings of the 5th International Conference on Advanced Research in Virtual and Rapid Prototyping, Leiria, Portugal, 28 September - 1 October, 2011, 2011

MATERIAIS 2022

Polymers

Materiais 2022

Polymers

MATERIAIS 2022

Polymers

MATERIAIS 2022

Materiais 2022

MATERIAIS 2022

Sustainability and Automation in Smart Constructions, 2020

Procedia Structural Integrity, 2020

Procedia Manufacturing, 2017

Proceedings of the 5th International Conference on Advanced Research in Virtual and Rapid Prototyping, Leiria, Portugal, 28 September - 1 October, 2011, 2011

MATERIAIS 2022