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- Manufacturing a Better Future: Scientific Report 2018-2023Publication . Ruben, Rui Miguel Barreiros; Gaspar, Marcelo Rudolfo Calvete; Dias, Juliana Rosa; Ruben, Rui; Calvete Gaspar, Marcelo; Dias, Juliana; Politécnico de LeiriaThe Centre for Rapid and Sustainable Product Development (CDRSP) of the Polytechnic of Leiria (IPL) is a leading research center with the mission of contributing to scientific and technological development through new products, materials and processes that are more sustainable, effective, and efficient. The CDRSP is an organic research unit of the IPL. It was founded in May 2007 to promote economic competitiveness, social cohesion, and sustainable development through new, more efficient, and sustainable products, materials, and processes. Portuguese Additive Manufacturing Initiative (PAMI) was a project that finished in 2021 and CDRSP was the leader. PAMI was a network for fundamental research and development of new techniques for additive manufacturing. The PAMI network was part of the National Roadmap of Research Infrastructures of Strategic Interest to foster an intelligent distribution of the excellent infrastructures that already exist in the central region of Portugal, with different areas of specialty (mechanics, materials, biomedical, and electronics) to increase competitiveness and the capacity to fix the high-performance production sector.
- Development of a preliminary finite element model to assess the effects of friction on the residual limb of a transfemoral amputeePublication . Ramalho, Armando; Ferraz, Miguel; Gaspar, Marcelo; Capela, CarlosThe use of numerical modelling tools allows optimizing the development of complex anatomical artefacts, such as customized prostheses for lower limb amputees. These numerical tools make it possible to characterize the interfacial interactions taking place between different parts of the prosthesis and the residual limb. This allows for understanding which rectifications and fittings having to be made on the custom design of the artificial body part without the need for manufacturing and donning prostheses. To such end, current research focused on the development of a preliminary Finite Element Model to assess the effects of friction on the residual limb of a transfemoral amputee, as the friction on the contact between the soft tissues, the liner and the prosthesis of the amputee is of major importance for his/her health and comfort.
- From Knowledge to Action: How Portuguese Higher Education Students Engage with Circular Economy PrinciplesPublication . Pardal, Ana; Moreira, Anabela; Galacho, Cristina; Mateus, Dina; Viegas, Laura; Gaspar, Marcelo; Teixeira, Margarida Ribau; Manteigas, Vitor; Dinis, Maria Alzira PimentaThis study investigates the perceptions and practices of Portuguese higher education students regarding the circular economy (CE), emphasising their knowledge, attitudes, and behaviours toward sustainable resource management. Carried out by the Working Group on Circular Economy and Waste Management of the Portuguese Sustainable Campus Network (RCS), the research used an online survey targeting students from 20 higher education institutions (HEIs), resulting in 400 responses. The findings indicate that while students generally hold positive views of the CE, their understanding of its practical applications, such as waste reduction and resource efficiency, remains limited. Only a small proportion of students reported exposure to CE-related topics in their curriculum, revealing a gap in academic integration. This study also identifies significant demographic variations in CE awareness and practices, influenced by factors such as age, field of study, and employment status. These insights underscore the need for HEIs to strengthen CE education and actively involve students in hands-on sustainability initiatives, fostering a generation equipped to drive the transition toward a circular economy.
- Stakeholder Differences in Valued Hotel Green PracticesPublication . Julião, Jorge; Monteiro, Inês; Gaspar, Marcelo; Trindade, Maria AliceThis paper aims to compare the perceptions of hotel customers and hotel staff regarding the value of green hotel attributes. By examining both stakeholder groups, the study addresses a gap in sustainable hospitality research, which largely overlooks employee perspectives in favour of customer preferences. An exploratory, cross-sectional survey was conducted using structured questionnaires, administered to hotel guests (n = 307) and hotel staff (n = 89) in Porto, Portugal. Respondents rated 15 green hotel attributes using a five-point Likert scale. Demographic data were also collected to analyse perceptual differences across gender, age, income, and education. The results revealed that both customers and staff exhibited environmental awareness, though their prioritisation of specific green practices differed. Customers tended to value visible environmental measures, such as recycling bins, energy-saving light bulbs, and renewable energy signage, while staff placed greater emphasis on operational sustainability aspects, including low-flow plumbing fixtures, refillable soap dispensers, and durable goods used in service areas. These differences reflect the stakeholders’ distinct roles and experiences within the hotel ecosystem. This study enriches the discourse on sustainable hospitality by providing a dual-stakeholder analysis of green hotel attributes using a shared evaluative framework. The findings offer practical insights for hotel managers aligning sustainability strategies with the expectations of both guests and employees, supporting more effective and inclusive green implementation in the lodging sector.
- Enhanced reconditioning of heavy-duty pulp industry equipment: Advantages of abrasive waterjet cuttingPublication . Ramalho, Armando Lopes; Silva, Agostinho da; Gaspar, Marcelo Calvete; Capela, Carlos; Celorrio-Barragué, Luis; Glăvan, Dan OvidiuWithin a pulp industry production process, a drop in the performance of a wood log rotary debarker was identified. Such loss of performance was due to the occurrence of excessive wear of the device's cutting blades, requiring their regular and premature replacement. The material used to manufacture the cutting blades, Hardox 500, has characteristics considered adequate for the required use. However, it was concluded that the blade manufacturing process degraded its mechanical properties, leading to its premature wear when placed in service. The present study intends to propose, characterize, and validate an alternative cutting process to manufacture the debarker's cutting blades. Abrasive waterjet cutting technology was proposed to produce the cutting blades. The suitability of this manufacturing process is discussed considering the specified geometry and the material characteristics of the resulting cutting blades.
- 3D printed models-based lab activities to enhance learning-teaching processes in Structural Engineering coursesPublication . Celorrio-Barragué, Luis; Calvo-Simón, Sergio; Gaspar, Marcelo; Vidal-Cortés, Mariano; Martín-Ramos, PabloThree-dimensional (3D) printing is a promising tool in Engineering education, as it can facilitate learning, contribute to the development of key skills and competences, increase the engagement and interest of students, and promote their creativity. In this work, a set of laboratory activities aimed at enhancing the learning-teaching experience of sophomore and junior students of engineering degrees related to structures is presented. To improve their understanding and their ability to calculate the stability, strength and rigidity of built structures, the use of 3D printed models is put forward. These printed models can be used as specimens in lab tests and also as visualization objects to improve students' comprehension in lectures. Moreover, they offer interesting advantages in terms of their lower cost, easy manipulation, low weight and short time of production. Five lessons, designed for Strength of Materials and Theory of Structures courses, which cover tensile testing, the analysis of truss and plane frames, bolted and welded joints, and constructive details in reinforced concrete structures are discussed.
- Design of Pyrolysis System to Convert Waste Plastic to FuelsPublication . Oliveira, Nelson S.; Pardo, Michael; Capela, Carlos; Gaspar, Marcelo; Vasco, Joel; Heleno, LizeteThe conventional recycling technology to process waste plastic, mechanical recycling, is not suitable to recycle waste thermoplastic with high content of contamination. Pyrolysis is a promising technology since it can convert into valuable products, such as fuels and monomers. This study focused on the design of the pyrolysis equipment for waste plastic based on polyolefins. The feeder of waste plastic is a worm screw conveyor that will be in a pre-heating system. The batch reactor has support for catalyzer and can operate between 300 up to 600 ºC with attached induction system for heating. The output flows into condenser in series to separate two liquid phases and gases, depending on its boiling point. The 3D model was done with SolidWorks, control system modelled in CADe SIMU and particle simulation with FloXpress.
- Feasibility Study of the PET Fines Incorporation into Recycling ProcessesPublication . Nascimento, Bruna Guilherme do; Bozzola, Fernando; Vasco, Joel C.; Parnigoni, Milena; Capela, Carlos; Heleno, Lizete; Gaspar, Marcelo; Oliveira, Nelson S.Circular economy principles focus on the need to preserve natural resources and foster the use of environmentally sustainable practices. Concerning the use of plastics in a circular economy, increasingly demanding solutions have to be developed towards the zero-waste goal sought after by researchers and society alike. Particular attention has been put into the recycling of PET, mainly due to its wide spectrum of use and, consequently, to large volumes of related waste. The PET mechanical recycling process requires these waste materials to be shredded into PET flakes. Following such a procedure, these flakes are pelletized to be used again as feedstock. Considering the main stages of the mechanical recycling processes, which include plastic screening, shredding and washing, significant amounts of end waste materials are generated. This end-waste integrates small scale particles that are designated by plastic fines. Concerning the PET recycling process, the PET fines resulting from its mechanical recycling are not currently valued due to several technical issues, such as their high contamination level and the complexity of sorting them from other small-size particles. Current research focuses on the feasibility of incorporating these PET fines into the film/injection extruders, avoiding this way the need for an intermediate pelletization stage. To allow for such direct incorporation of PET fines into recycling processes, different decontamination and sorting solutions were implemented and tested. The current study is based on analyzing the mechanical properties of PET fines, using laboratory tests such as FTIR, DSC, MFI, moisture content, tensile tests and bending tests. Preliminary results allow foreseeing the successful direct incorporation of PET fines into PET recycling.
- Ink Removal on Plastic Films Printed by FlexographyPublication . Bozzola, Fernando; Nascimento, Bruna Guilherme do; Vasco, Joel C.; Silva, Nelson; Lagoa, Fernando; Capela, Carlos; Heleno, Lizete; Gaspar, Marcelo; Oliveira, Nelson S.Plastics are key engineering materials for our society and economy, mainly due to their multifunctionality and ease of processing. Nonetheless, their main drawback is related to the fact that when these cannot be reprocessed, they do generate waste, which leads to several environmental impacts. Therefore, considering plastics’ circularity, minimizing their waste, and the resulting impacts, stresses the need for these to be recyclable. One of the main challenges that concern their recyclability is the deinking of plastic films when printed by flexography. The current technology uses non-bio-based surfactants and non-renewable surfactants, which are harmful to the environment. Therefore, the main objective of current research is to develop an environmentally sustainable process for ink removal on printed post-industrial flexible plastic films using bio-based surfactants. This process focuses on obtaining a deinked plastic that may be reprinted, avoiding this way for inappropriate disposal or reprocessing problems. The value increase of upcycling such post-industrial waste makes it possible to match the quality of the virgin plastic, which is key to carrying out an effective cost analysis of recycled plastic when compared to the new plastic films. Dedicated laboratory deinking procedures were undertaken with transparent polyethylene films printed by flexography with different conditions. Preliminary results show the dedicated experimental ink removal procedure using bio-based surfactants to be effective and environmentally sustainable.
- Recycling of PET fines waste by density separation: a way to circularity of plasticPublication . Heleno, M. L.; Oliveira, N. S.; Gaspar, M.; Silveira, A.; Vasco, J.Plastic is one of the most used materials due to its specific characteristics such as high flexibility and impact resistance, low cost, formability, light weight and recyclability. In this set, polyethylene terephthalate (PET) based materials are among of the most used plastics on the packaging market worldwide. The European strategy for plastics aims to modify the processes of design, production, use and recycling of plastics. It becomes crucial to study solutions to enhance the circularity of plastics in recycling processes. Therefore, it is mandatory to evaluate the potential separation of PET fines resulting from the recycling process of PET bottles (post-consumer waste), which are still contaminated by other polymers and other materials. The recovery of PET fines was successfully achieved with a multistage density plastics separation process, consisting on the use of solutions of different densities and ensuring the adequate wettability of the residues in the solutions. The addition of this multistage separation process by plastics density, improves PET fines recovery, by achieving 91.7% of pure PET fines from plastic material waste.