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• X-ray tomography investigation of the use of veils to improve the impact tolerance of thin-ply composite laminates

  S. García-Rodríguez, J. Costa, J. Arbeláez, A. Lahti, A. Quintanas-Corominas, S. Medina

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 139

  
  

  Abstract

  Interleaving high fibre areal weight veils, typically used to improve the interlaminar fracture toughness and impact tolerance of composite laminates, impairs their tensile and compressive properties. We characterized the mechanical response of a thin-ply quasi-isotropic baseline laminate and laminates interleaved with two types of light (4 g/m2) co-polyamide veil: tension, compression, mode-I interlaminar fracture toughness, impact and compression after impact. X-ray tomography provided comprehensive understanding into the effect interleaving has on the microstructure, impact resistance and fracture process zone of double cantilever beam specimens. The veil fibre diameter was the key-parameter controlling the tensile properties (the veil with thinner fibres avoided resin accumulation at the interfaces and left the baseline tensile properties unaffected). The adhesion between veil fibres and resin controlled mode-I interlaminar fracture toughness (the veil with a suspected higher adhesion deflected crack propagation to the surrounding 0° plies, which enhanced mode-I interlaminar fracture toughness by 43%). Both veils reduced pristine compressive strength by up to 9%; however, the veil with thinner fibres improved CAI strength by up to 28% for impact at 14 J.

  Abstract
  Interleaving high fibre areal weight veils, typically used to improve the interlaminar fracture toughness and impact tolerance of composite laminates, impairs their tensile [...]

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• Magnetic properties and applications of glass-coated ferromagnetic microwires

  V. Zhukova, ,. Corte-León, M. Ipatov, J. Blanco, J. Oliveraa, A. Zhukov

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 138

  
  

  Abstract

  The impact of post-processing on soft magnetic properties and the giant magnetoimpedance (GMI) effect of Fe- and Co-based glass-coated microwires is evaluated. A remarkable improvement of magnetic softness and GMI effect is observed in Fe-rich glass-coated microwires subjected to stress annealing. Frequency dependence of GMI ratio of stress-annealed Fe-rich microwires has been discussed considering frequency dependence of the skin penetration depth, δ, as well as magnetic anisotropy distribution within the metallic nucleus. Annealed and stress-annealed Co-rich microwires present rectangular hysteresis loop and single and fast domain wall propagation. However, Co-based stress-annealed microwires present high magnetoimpedance ratio. Observed stress-induced anisotropy and related changes of magnetic properties are discussed considering internal stresses relaxation and “back-stresses”.

  Abstract
  The impact of post-processing on soft magnetic properties and the giant magnetoimpedance (GMI) effect of Fe- and Co-based glass-coated microwires is evaluated. A remarkable [...]

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• Smart composites with magnetic microwire inclusions allowing non-contact stress and temperature monitoring

  A. Allue, P. Corte-León, K. Gondra, V. Zhukova, M. Ipatov, J. Blanco, J. González, A. Zhukov

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 137

  
  

  Abstract

  We observed evolution of the transmission and reflection parameters of the composites contaning magnetic microwire inclusions during the composites matrix polymerization. A remarkable change of the reflection and transmission in the range of 4-7 GHz upon the matrix polymerization is observed. Observed dependencies are discussed considering variation of temperature and stresses during the thermoset matrix polymerization and their influence on magnetic properties of glass-coated microwires. Obtained results are considered as a base for novel sensing technique allowing non-destructive and non-contact monitoring of the composites utilizing ferromagnetic glass-coated microwire inclusions with magnetic properties sensitive to tensile stress and temperature.

  Abstract
  We observed evolution of the transmission and reflection parameters of the composites contaning magnetic microwire inclusions during the composites matrix polymerization. [...]

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• Epoxy resins used in rollers for the paper manufacturing with improve mechanic properties, conductivity and roughness

  N. Lardiés, J. Garcés, A. Navarro

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 136

  
  

  Abstract

  Big rollers are used in the paper manufacturing industry, they are composed of layers of different materials (metallic core, polyurethane and composite with epoxy resin between others). The company TECNOCAUCHO is dedicated to the manufacturing of these rollers and towether with AIMPLAS have modified two epoxy resins that are used in two rollers (guide and calendering). In both cases the epoxy resin layer was the weak point of the rollers, consequently the mechanic properties of the resin were improved in order to extend the useful life of each roller and also the conductivity of the guide roller and the roughness and brightness of the calendering roller were improved. Currently, a epoxy resin with the improved properties achieved in this paper is not available on the market. Guide roller: mechanic properties of the epoxy resin were improved 7,7% compared to original comercial resin through nanofiller addition. Besides, resistivity values below 100 Ωm (company´s target value) were achieved, minimizing the sparks generation. Calendering roller: mechanic properties were improved to 18,6% (tensile strenght at 130ºC), brightness and roughness (Rz below to 0,2 microns, company´s target value) through nanofillers addition, improving significantly the superficial properties of the paper.

  Abstract
  Big rollers are used in the paper manufacturing industry, they are composed of layers of different materials (metallic core, polyurethane and composite with epoxy resin between [...]

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• Composite epoxy matrixes Bisphenol A free

  S. Paz, P. Prendes, R. Meizoso, . X.Yáñez

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 135

  
  

  Abstract

  Although Bisphenol A content in epoxy resins based on it (called Bisphenol A diglycidyl ethers, BADGE) is practically undetectable using nowadays analytical techniques, Bisphenol A is a controversial product due to its toxicology. For this reason, epoxy resins in general and composite epoxy matrices in particular are in focus of scientific and social media. We studied several alternatives both petroleum-based (e.g. trimethylolpropane or entaerythritol) and bio-based (e.g. isosorbide, lignin or sorbitol). The main objective of these BADGE alternatives is to obtain products that could be adapted to the requirements of the composite market with minor differences respect to Bisphenol A epoxy derivatives in morphological, chemical, mechanical and thermal properties.

  Abstract
  Although Bisphenol A content in epoxy resins based on it (called Bisphenol A diglycidyl ethers, BADGE) is practically undetectable using nowadays analytical techniques, Bisphenol [...]

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• Temperature effects on the microstructure and on the mechanical response of 3D printed continuous carbon fibre reinforced polymers

  P. Martín, C. Pascual-Gonzalez, J. Jiménez, M. Iragi, L. Aretxabaleta, C. Lopes

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 134

  
  

  Abstract

  The state-of-the-art additive manufacturing technology of continuous carbon fibre reinforced polymers (CFRP) is based on fused filament fabrication (FFF), which has a great potential for reproducing robust and complex geometries. However, 3D printed CFRP present relatively poor mechanical properties in comparison to traditional composites. This work analyses post-processing temperature effects on the microstructure and on the interlaminar mechanical properties of the printed CFRP. Post-processed pieces at 150°C (exceeding matrix glass transition) showed a reduction of porosity by 80% and improved mechanical properties by 250% with respect to unprocessed pieces.  

  Abstract
  The state-of-the-art additive manufacturing technology of continuous carbon fibre reinforced polymers (CFRP) is based on fused filament fabrication (FFF), which has a great [...]

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• Molds manufactured with 3D printing for UV curing using Light-RTM

  . L.Buruaga, I. Saenz-Dominguez, . M.Baskaran, . A.Esnaola, . I.Tena, J. Aurrekoetxea

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 4 - Aplicaciones de los materiales compuestos. Nuevos procesos de fabricación y materiales compuestos avanzados.), 133

  
  

  Abstract

  Ultraviolet (UV) curing is a competitive process both in terms of cycle time and energy consumption. However, it is limited to open mold processes where the material can be irradiated directly with UV light. There is a variant of RTM, Light-RTM, in which the flexible semi-mold can be manufactured with transparent/translucent materials and in small thicknesses. In the present work the feasibility of performing the semi-mold by stereolithography (SLA) has been studied. The photocurable resin selected for SLA was the high temperature resin from FormLabs. First, the UV light transmission has been characterized according to the thickness of the semi-mold wall, in which the mold thickness has been determined in 3 mm. The ageing process has also been analysed, characterising the variation of the transmitted spectrum as a function of the irradiation time for a 3 mm thick plate, where a loss of light transmission of approximately 13 % has been observed for 15 minutes of exposure time. Finally, a semi-mold has been manufactured for the manufacture by Light-RTM of a 150 mm × 40 mm × 2 mm flat plate. During the process, there were no problems of vacuum loss and the intensity of UV light that passes through the semi-mold allows curing the photocurable matrix of the composite material.

  Abstract
  Ultraviolet (UV) curing is a competitive process both in terms of cycle time and energy consumption. However, it is limited to open mold processes where the material can be [...]

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• Manufacturing of carbon fiber reinforced PET from wastes of CFRP and PET bottles

  S. Armentia, J. Sierra, J. Abenojar

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 130

  
  

  Abstract

  This work is focused on two current and important issues. On one hand, 12 millions of tons of PET are thrown into the sea each year. In fact, in spite of being a recyclable polymer, less than 50 % of processed PET is recycled in Europe. On the other hand, thermoset matrix composites are widely used in the industry and the end-of-life products and scraps need to be recycled. Compared to thermoplastics, thermosets present a problem for being recycled or remolded due to their irreversible curing. Many researches are focused on the recycling of carbon fiber reinforced epoxy, presenting three different paths: mechanical, thermal and chemical recycling. Thermal recycling is the most promising because it allows to recover clean fiber. However, it is an energetically expensive and non-environmentally friendly process. Chemical recycling, for its part, needs hazardous products, such as nitric acid, to dissolve the matrix. Finally, both, fibers and matrix, are recovered with mechanical recycling which consists on milling the composite to obtain finer parts. In this work, unidirectional carbon fiber reinforced epoxy is blade-milled and it is used as reinforcement of a new composite. As matrix, PET coming from recycled bottles is used. First of all, pellets of PET are produced from the bottles with a blade mill. Recycled composite and PET are mixed and a sheet is manufactured with a hot plates press. The resulting material is chemically and mechanically tested.

  Abstract
  This work is focused on two current and important issues. On one hand, 12 millions of tons of PET are thrown into the sea each year. In fact, in spite of being a recyclable [...]

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• Ternary cements as a sustainable alternative in Civil Engineering

  C. Rodriguez, J. Ortega, M. Hernandez, M. Iniesta-Castilloa

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 129

  
  

  Abstract

  Construction industry is among the most polluting human activities, mainly due to CO2 emisions produced during portland cement manufacture. The cement production industry has incorporated byproducts of other industries, to produce a more sustainable material. This would be due to the decrease of raw materials, treat byproducts in a safe way, and improve the properties of the cement manufactured. The durability of the structures would also be improved. The main problem is that the properties are not good in the short term. In the last years there have been many efforts regarding the incorporation of two or more aditions, because they produce a synergic effect that improve the properties of concrete or mortars. This type of cements has been called ternary cements In this work ternary cements have been produced using three different aditions: ground granulated blast furnance slag, and fly ashes, as active aditions, and limestone filler as a non-active adition. The total amount of addition is limited to a 35% maximum, for all of them together, as it is stated in the instruction for structural concrete, EHE-08. 35% is the maximum adition allowed for concrete production, and always added to ordinary portland cement. Mechanical properties and some durability parameters have been studied in the short terms for both a ternary cement and the results have been compared with a binary cement.The results are promising, and show a good behavior, what means that these cements could be safely used in real structures.

  Abstract
  Construction industry is among the most polluting human activities, mainly due to CO2 emisions produced during portland cement manufacture. The cement production industry [...]

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• Eco Sustainable Rail: production of sustainable railway sleepers from mixed plastics waste

  . B.P.Silva, . M.C.Paiva, . J.P.Nunes, H. Martins, . A.Vilela, . A.Marques, . S.Castro, . R.Rodrigues, . J.Amaro, . S.Santos, . P.Gaiato, . A.Mota, . J.Carvalho

  Materiales Compuestos (2022). Vol. 04 - Comunicaciones Matcomp19 (2020), (Núm. 3 - Materiales bioinsipirados), 127

  
  

  Abstract

  Mixed plastics waste (MPW) constitute a material of extreme recycling difficulty due to their heterogeneity and contamination level. As a consequence, a large fraction of MPW is landfilled. It is imperative to find new applications for MPW that bring new value as a raw material, with application in high added-value products. The restrictions on the marketing and application of biocidal products such as the creosote treatment performed on wood railway sleepers, introduced by Directive 98/8/EC, triggered the replacement of several products traditionally produced in wood. Currently, there is a global need to find solutions for replacement of wood railway sleepers for specific railway applications. The present study investigates the application requirements and proposes a new solution based on MPW composites for the production of eco-friendly railway sleepers. The composites are mostly based on MPW and glass fibers. The prototype composite sleepers were produced by intrusion processing and tested in simulated mechanical and environmental operating conditions. Overall this new circularity approach will largely contribute to reduce the deposition of MPW in landfills, responding to a current need of the railway sector, and will contribute to implement circular economy and resource efficiency.

  Abstract
  Mixed plastics waste (MPW) constitute a material of extreme recycling difficulty due to their heterogeneity and contamination level. As a consequence, a large fraction of [...]

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