26 documents found, page 1 of 3
Polymer sorting through fluorescence spectra
Penso, Camila Maria Ramos Aires Moreira; Castanheira, Elisabete M. S.; Paiva, Maria C.; Gonçalves, L. M.This study identifies different polymers using their fluorescent data under various light wavelengths that ranged from 245 nm to 345 nm in 10 nm intervals. The primary goal of the proposed method is to select optimal wavelengths that can lead to the accurate identification of six polymers: polyamide 6 (PA6), polymethyl methacrylate (PMMA), polypropylene (PP), polystyrene (PS), high-density polyethylene (HDPE), ...
High lignin content polymer filaments as carbon fibre precursors
Ribeiro, Rui; Guerreiro, Miguel; Reis, Renato; Martins, Joana T.; Vieira, J.M.P.; Silva, Mariana Martins da; Covas, J. A.; Paiva, Maria C.The growing environmental awareness, the search for alternatives to fossil resources, and the goal of achieving a circular economy have all contributed to the increasing valorization of biowaste to produce bio-based polymers and other high-value products. Among the various biowaste materials, lignin has gained significant attention due to its high aromatic carbon content, low cost, and abundance. Lignin is pred...
Synergistic effects in hybrid buckypapers of graphene nanoplatelets and carbon ...
Silva, Thais da; Silva, Thiély da; Corrêa, Rieyssa; Ribeiro, Rui; Morgado, Guilherme; Montagna, Larissa; Uribe, Braian Esneider BuitragoHybrid buckypapers (BPs) composed of graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) hold great potential for applications in flexible electronics, electromagnetic shielding, and energy storage. In this study, hybrid BPs were fabricated and characterized to evaluate their structural, thermal, and electrical properties. Hybrid BPs with varying GNP/CNT mass ratios (0/100, 25/75, 50/50, 75/25, 85/15, 90/...
High-performance PEEK/MWCNT nanocomposites: Combining enhanced electrical condu...
Silva, Sofia; Barbosa, José M.; Sousa, João D.; Paiva, Maria C.; Teixeira, Paulo F.High-performance engineering thermoplastics offer lightweight and excellent mechanical performance in a wide temperature range. Their composites with carbon nanotubes are expected to enhance mechanical performance, while providing thermal and electrical conductivity. These are interesting attributes that may endow additional functionalities to the nanocomposites. The present work investigates the optimal condit...
Multi-scale experimental investigation on the structural behaviour of novel nan...
Abbass, Ali; Oliveira, Daniel V.; Lourenço, Paulo B.; Paiva, Maria C.Natural fibre composites present a very appealing area of research for the structural strengthening of masonry structures. Natural fibres possess several drawbacks, such as low initial stiffness and poor interfacial bond behaviour with inorganic matrices that hinder their functions. Such challenges were overcome by applying an innovative nanocomposite-based impregnation system that was pre-engineered and presen...
Application of sound waves during the curing of an acrylic resin and its compos...
Uribe, Braian Esneider Buitrago; Rodrigues, Joana; Costa, Pedro; Paiva, Maria C.Research into particulate polymer composites is of significant interest due to their potential for enhancing material properties, such as strength, thermal stability, and conductivity while maintaining low weight and cost. Among the various techniques for preparing particle-based composites, ultrasonic wave stimulation is one of the principal laboratory-scale methods for enhancing the dispersion of the disconti...
Shape-memory polymers based on carbon nanotube composites
Silva, Mariana Martins da; Proença, Mariana Paiva; Covas, José António; Paiva, Maria C.For the past two decades, researchers have been exploring the potential benefits of combining shape-memory polymers (SMP) with carbon nanotubes (CNT). By incorporating CNT as reinforcement in SMP, they have aimed to enhance the mechanical properties and improve shape fixity. However, the remarkable intrinsic properties of CNT have also opened up new paths for actuation mechanisms, including electro- and photo-t...
Amination of polymeric braid structures to improve tendon healing: An experimen...
Peixoto, Tânia; Silva, Daniel; Rodrigues, Miguel; Neto, Miguel; Silva, Rui; Paiva, Maria C.; Grenho, Liliana; Fernandes, Maria Helena; Lopes, Maria A.Several polymers are researched for tendon repair as polyethylene terephthalate (PET) and polylactic acid (PLA). These are biocompatible and useful in scaffolding repair though with minimal success due to long-term failure. There is a need to improve such scaffolds’ design and physical–chemical nature. This work concerns surface functionalization of polymeric braids (PET and PLA) that fulfill the high mechanica...
Engineering ligament scaffolds based on PLA/graphite nanoplatelet composites by...
Silva, Magda Sofia Gonçalves; Pinho, Isabel; Gonçalves, Hugo; Vale, Ana C.; Paiva, Maria C.; Alves, Natália M.; Covas, J. A.The development of scaffolds for tissue-engineered growth of the anterior cruciate ligament (ACL) is a promising approach to overcome the limitations of current solutions. This work proposes novel biodegradable and biocompatible scaffolds matching the mechanical characteristics of the native human ligament. Poly(L-lactic acid) (PLA) scaffolds reinforced with graphite nano-platelets (PLA+EG) as received, chemica...
Biocompatible 3D-printed tendon/ligament scaffolds based on polylactic acid/gra...
Silva, Magda Sofia Gonçalves; Gomes, Susana; Correia, Cátia Sofia Palma; Peixoto, Daniela; Vinhas, Carla Adriana Araújo; Rodrigues, Márcia T.Three-dimensional (3D) printing technology has become a popular tool to produce complex structures. It has great potential in the regenerative medicine field to produce customizable and reproducible scaffolds with high control of dimensions and porosity. This study was focused on the investigation of new biocompatible and biodegradable 3D-printed scaffolds with suitable mechanical properties to assist tendon an...