349 documents found, page 1 of 35
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...
Potentialities of cellulose nanofibers (CNFs) in low density polyethylene (LDPE...
Agnes, Erick Afonso; Hillig, Everton; Zattera, Ademir José; Beltrami, Lilian Rossa; Covas, J. A.; Hilliou, L.; Sousa, João Duarte Alves; Calado, LeonorThe growing demand for polymeric materials has made them signifcant in both industry and the environment, and the task of making them sustainable is becoming increasingly challenging. Cellulose presents an opportunity to minimize the efect of nondegradable materials. Cellulose nanofbers (CNFs) are a class of cellulose fbers with superior performance due to their high strength and stifness combined with low weig...
Can biomass mastication assist the downstreaming of polyhydroxyalkanoates produ...
Souza, Hiléia Karla Silva; Matos, Mariana; Reis, Maria A. M.; Covas, J. A.; Hilliou, L.Polyhydroxyalkanoates (PHAs) are natural polyesters which biodegrade in soils and oceans but have more than double the cost of comparable oil-based polymers. PHA downstreaming from its biomass represents 50% of its overall cost. Here, in an attempt to assist downstreaming, mastication of wet biomasses is tested as a new mechanical continuous biomass pretreatment with potential for industrial upscaling. Downstre...
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...
Experimental validation of a micro-extrusion set-up with in-line rheometry for ...
Sousa, João; Teixeira, Paulo F.; Hilliou, L.; Covas, J. A.The main objective of this work is to validate an in-line micro-slit rheometer and a micro-extrusion line, both designed for the in-line monitoring and production of filaments for 3D printing using small amounts of material. The micro-filament extrusion line is first presented and its operational window is assessed. The throughputs ranged between 0.045 kg/h and 0.15 kg/h with a maximum 3% error and with a melt ...
Incorporation of argan shell flour in a biobased polypropylene matrix for the d...
Jordà-Reolid, María; Moreno, Virginia; Martínez-Garcia, Asunción; Covas, J. A.; Gomez-Caturla, Jaume; Ivorra-Martinez, Juan; Quiles-Carrillo, LuisIn this study, a new composite material is developed using a semi bio-based polypropylene (bioPP) and micronized argan shell (MAS) byproducts. To improve the interaction between the filler and the polymer matrix, a compatibilizer, PP-g-MA, is used. The samples are prepared using a co-rotating twin extruder followed by an injection molding process. The addition of the MAS filler improves the mechanical propertie...
The application of 3D-digital image correlation and analytical approaches on th...
Kharrat, Fatma; Khlif, Mohamed; Hilliou, L.; Nouri, Hedi; Covas, J. A.; Bradai, Chedly; Haboussi, MohamedThe mechanical characterization of plastic films is often complicated by their relative frailty and small thickness. When practical applications involve biaxial stress loading, the bulge test seems to be the most simple and suitable approach. In this work, polylactic acid (PLA) film and biocomposites PLA films filled with 1, 2 and 5 wt% of date palm leaf filler (DPLF) obtained by extrusion film blowing were sub...
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...
Bulge test technique and digital image correlation for the determination of the...
Kharrat, Fatma; Chaari, Rania; Khlif, Mohamed; Hilliou, L.; Covas, J. A.; Haboussi, Mohamed; Bradai, ChedlyThe bulge test is a versatile mechanical testing technique that can be used for a wide range of of applications in materials science, engineering, and biomedical research, and is a valuable tool for understanding the mechanical behavior of materials and structures. In this present work, the construction of a pneumatic bulge test apparatus dedicated to characterizing 50 micrometers-thick PLA films was detailed. ...
Application of the bulge test combined with 3D-DIC for biaxial characterization...
Kharrat, F.; Khlif, M.; Hilliou, L.; Covas, J. A.; Haboussi, M.; Bradai, C.The bulge test is a versatile mechanical testing technique widely applied in materials science, engineering, and biomedical research to understand the mechanical behavior of materials and structures. In this study, PLA blown films were characterized through the bulge test, and the corresponding properties were compared to those obtained from uniaxial t!esting. To achieve more accurate and precise deformation me...