Carlos Fuentes

Luxembourg Institute of Science and Technology (LIST) | LIST · Materials Research and Technology (MRT)

Vietnam grown coir fibres have been studied for use in composite materials. In order to understand the fibre-matrix interfacial compatibility, it is necessary to investigate the wetting behaviour and surface chemistry of the fibres. The aim of this paper is to develop a wetting measurement procedure to determine stable and reproducible advancing st...

Bamboo fibres recently attracted interest as a sustainable reinforcement fibre in (polymer) composite materials, due to specific mechanical properties which are comparable to glass fibres. To achieve good wetting and adhesion of the bamboo fibre with different polymers, the fibre surface needs to be characterized. The wetting behaviour of technical...

This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of technical fibres of hemp used for composite applications. First, the strength and apparent Young’s modulus distribution of technical fibres of hemp of 96 hemp samples, corresponding to 32 different hemp accessions...

Atmospheric plasma activation and plasma coating with 3-aminopropyltriethoxysilane (APTES) were used to investigate the effect of a modified interface on the creep behaviour of flax fibre reinforced polyoxymethylene composite. The wetting parameters and the interfacial shear strength indicate that using air-based plasma activation is superior to pl...

Natural fibre composites are increasingly explored for structural applications due to improvements in mechanical performance. For this, damage prognostics are crucial. We integrate acoustic emission (AE) and deep learning techniques to predict the remaining useful life of a flax fibre composite under long-term creep load. Derivatives of cumulative...

Cellulose nanocrystals (CNCs) and cellulose microfibrils (CMFs) are promising materials with the potential to significantly enhance the mechanical properties of electrospun nanofibers. However, the crucial aspect of optimizing their integration into these nanofibers remains a challenge. In this work, we present a method to prepare and electrospin a...

This study explores enhancing the compatibility of bamboo fibers (BF) for composite through chemical modifications. A novel polydopamine (PDA) treatment was developed, using polyethyleneimine (PEI) to obtain a stable PDA solution and was compared to conventional in situ PDA polymerization. Untreated BF were subjected to PDA and polydopamine-polyeth...

In response to global awareness of environmental preservation and economic challenges associated with polymer-based composite materials, there is a growing interest in renewable resources and agro-industrial materials. Bamboo fibers (BF) are a promising alternative to synthetic fibers. Despite their high strength and Young's modulus, and biodegrada...

In the realm of 3D printing, fiber-reinforced composites (FRC) offer immense potential for enhancing structural and mechanical properties. This study aims to investigate the enhancement of mechanical properties of electrospun fibers through two methods: regeneration by deacetylation and incorporation of cellulose nanocrystals (CNCs) derived from su...

This paper explores a strategy that integrates acoustic emission (AE) and deep learning techniques for the remaining useful life (RUL) prediction of flax fibre composite subjected to long-term flexural creep load. The AE and creep deformation data were acquired by monitoring the creep rupture (run to failure) tests under four different stress level...

The characterization of natural fibers, particularly in understanding their morphological features, and their influence in their mechanical behavior, faces several challenges. On the morphology perspective factors as aspect ratio, geometrical transitions of the organic geometry, presence of defects play a role in the material response. Moreover, th...

This work aims to reveal the damage mechanisms and evolution in unidirectional flax fibre biocomposites when subjected to creep load. X-ray micro computed tomography and acoustic emission (AE) was used to monitor the failure progress during flexural creep tests. A correlation between the event clusters and directly observed damage modes was establi...

Hybrid PTFE/Kevlar fabric reinforced epoxy composites have widely been used as structural self-lubricating liners. To achieve the best working performance, the Kevlar rich side has to be well impregnated (good wettability), whereas the PTFE rich side must remain dry at the same time. Consequently, it is essential to study the wetting properties of...

The interfacial properties of carbon fiber (CF) reinforced thermoplastic composites depend strongly on the wettability and surface characteristics of the reinforcing fibers, and their compatibility with a chosen matrix. The interface between conventional fibers and thermoplastic matrices is generally weak, due to a lack of specific chemical interac...

The grassland ecosystems in the central Andes of Peru, have extensive vegetation formations dominated by tussock grasslands that are not consumed by Andean livestock (Andean camels, cattle, and sheep), so they are burned by rural inhabitants to cause tender shoots, but that cause serious consequences for the ecosystem and its ecosystem services; ho...

The tall grass vegetation in the Andean grassland ecosystems covers the largest area compared to other types of vegetation such as Puna grass, wetland and others. The grasslands are frequently set on fire by livestock farmer, seriously affecting the ecosystem. One way to mitigate this problem is to use these species as a source of plant fibre, whic...

This study evaluates the influence of moisture sorption on the properties of flax fibres and their composites. The radial swelling of both the elementary and technical flax fibres at a wide range of relative humidity (RH) values is determined. Moreover, the effects of moisture sorption on both the thickness swelling and flexural properties of flax/...

Printing is inherently associated with the deposition of liquids on solid substrates. In other words, wetting plays a key role in the printing process. However, most fabrics have a complex architecture and it is difficult to control how liquids behave at their contact. To acquire a comprehensive view on the wetting properties of textile, we current...

Hypothesis Measuring contact angles made by liquids around individual carbon fibers (CFs) using the Wilhelmy technique is a conventional method to evaluate their surface properties. However, despite its apparent simplicity, inaccurate measurements of capillary forces and wetted lengths, due to the fineness of the CFs, as well as an improper selecti...

This manuscript presents a new approach to measure the cross sectional areas of elementary fibres using micro-computed tomography. The correct and accurate measurement of the area allows a correct characterization of the strength of the fibre. The accuracy and reliability of tomography was validated through the determination of cross-sectional area...

Natural materials such as wood exhibit high mechanical properties through cellulose structured at multiple length scales and embedded in a matrix of similar chemical structure. These hierarchical materials have inspired the design of lightweight composites composed of naturally occurring polymers. However, the close proximity of melt and decomposit...

Natural fibers, such as bamboo, flax, hemp, and coir, are usually different in terms of microstructure and chemical composition. The mechanical properties of natural fibers strongly depend on the organization of cell walls and the cellulose micro-fibril angle in the dominant cell wall layers. Bamboo, flax, and hemp are known for high strength and s...

Bamboo fibres were exposed to ultraviolet light (UV) radiation to degrade and remove the lignin layer on the surface of the fibre, in order to improve the interfacial bonding strength between fibres and polyvinylidene fluoride (PVDF). Before and after surface treatment, the chemical groups on the fibre surface were analysed through x-ray photoelect...

Natural fibre (NF) reinforced composites offer high specific mechanical properties and are an ecological alternative to synthetic fibre-reinforced composites. While having great potential, their use today is limited to non-structural applications, mostly with epoxy or polypropylene matrices. This work studies suitable high-performance thermoplastic...

Hypothesis The architecture of complex-shaped fibres affects the motion of the contact line and the evolution of its associated menisci when a fibre is immersed into a liquid. Understanding and predicting the motion of the contact line is critical in the design of complex-shaped fibres for many engineering applications as well as for surface scienc...

Four Phyllostachys species grown in Europe were analysed with the aim of extracting long bamboo fibres for composite applications. The morphological characteristics of the plant were determined and compared to the species grown in their native region. Though the species tend to grow smaller, the Phyllostachys vivax showed similar Young’s modulus as...

Aramid is already a widely used synthetic fibre in many different high performance composite materials due to its high strength-to-weight ratio and impact resistance. In order to predict the behaviour of these highperformance composite materials, it is not only important to understand the mechanical behaviour of both the fibre and matrix phases the...

To evaluate compatibility between a substrate and a thermoplastic polymer, the established methodology is to estimate their surface composition in terms of surface energy components, utilizing the results of contact angle measurements of probe liquids onto substrate and polymer surfaces at room temperature. Using this methodology, polymer surfaces...

This manuscript describes the effects of alterations in biochemical composition on structural morphology and the mechanical behaviour of elementary and technical fibres of hemp used for composite applications. First, the strength and apparent Young's modulus distribution of technical fibres of hemp of 96 hemp samples, corresponding to 32 different...

Fused deposition modeling (FDM), a low-cost and easy-to-use additive manufacturing technique, was used to produce poly(lactic acid) (PLA) gyroid scaffolds. Such morphology was selected for its spring shape, high porosity leading to good nutrient and waste diffusion, and favorable mechanical properties. Printing parameters were optimized and the nee...

The importance of the interphase as the material part for transferring stress is widely recognized [1]; however, the wetting behaviour of molten polymers during composite manufacturing or how the interface is formed at high temperature between the molten thermoplastic and the hot fibre surface are yet to be studied in detail. The final mechanical p...

Contact angle measurement, is a suitable method to characterize the wettability of a polymer matrix and reinforcing fibers, but it is highly challenging to measure the capillary force exerted by a probe liquid on a fiber accurately for very fine fibers like single carbon fibers. Therefore, we propose an innovative method for measuring dynamic conta...

Wetting dynamics drive numerous technological processes involving liquids in contact with solid substrates with a wide range of geometries. The spreading dynamics of organic liquids and liquid metals at, respectively, room temperature and above 1000 °C have been studied extensively, both experimentally and numerically [1, 2]. However, much less att...

Wetting dynamics drive numerous processes involving liquids in contact with solid substrates with a wide range of geometries. The spreading dynamics of organic liquids and liquid metals at, respectively, room temperature and above 1000 °C have been studied extensively, both experimentally and numerically. However, almost no attention has been paid...

This research presents a novel experimental approach to characterize the non-linear behaviour of technical hemp fibres, by combining standard tensile tests with a detailed full-field strain measurement at the micro-scale during tensile loading. First, the strength and Young's modulus distribution of technical hemp fibres of different variants were...

Carbon nanotube (CNT) fibers are interesting alternatives to carbon fibers as fibrous reinforcement. However, good interfacial adhesion between the fibers and the matrix is difficult to control. Wetting of the fiber reinforcement with the matrix strongly determines the interfacial strength. Therefore, accurate characterization of the wettability of...

Physical adhesion between Carbon Fibers (CFs) and polymer matrices as well as the formation of voids at the interface between these two materials are mostly controlled by the wetting properties of the fibers. Due to the hierarchical structure of CF reinforcements, it is essential to study their wetting behavior at different scales: from the single...

Physical adhesion between Carbon Fibres (CFs) and polymer matrices as well as the formation of voids at the interface between these two materials are mostly controlled by the wetting properties of the fibres. Due to the hierarchical structure of CF reinforcements, it is essential to study their wetting behavior at different scales: from the single...

Flax fibres were thermally treated, to prove that in the same manufacturing conditions, modifying wetting and swelling properties of fibres changes the flow during LCM processes and thus could enhance the final material health of composite parts. Swelling of untreated and treated fibres was measured with optical and tensiometric methods proving tha...

The interaction between fibres and polymer matrices has a significant effect on the mechanical properties of composite materials since the load distribution efficiency at the interface is determined by the degree of adhesion between the components. This strong fibre-matrix adhesion has to be obtained by interfacial interactions, including mechanica...

By mimicking the complex microstructure of natural fibres through micro 3D printing, and by synchronizing both the force and optical methods, the contributions of chemical surface composition and microstructure effects on the wettability of natural fibers can be decoupled. Technical coir and hemp fibers were used as reference natural fibers. They b...

By mimicking the complex microstructure of natural fibres through micro 3D printing, and by synchronizing both the force and optical methods, the contributions of chemical surface composition and microstructure effects on the wettability of natural fibers can be decoupled. Technical coir and hemp fibers were used as reference natural fibers. They b...

The wetting dynamics drive numerous technological processes involving all kind of liquids in contact with solid substrates showing eclectic geometries. If the spreading dynamics of both organic liquids and liquid metals at respectively room temperature and temperature above 1000°C have been and are still extensively studied experimentally and numer...

Wettability, i.e. contact angle measurement, is a suitable method to characterize the physical bonding of a polymer matrix and reinforcing fibers, but it is highly challenging to measure the capillary force exerted by a probe liquid on a fiber accurately for very fine fibers like single carbon fibers. Herein, we propose an innovative method for mea...

Natural fibres (NF) have shown to be a suitable alternative to glass fibres as reinforcing material in polymer composites since they offer similar specific strength and stiffness. Thus, those composites may be readily used in the automotive, sport and leisure. However, most of today's natural fibre applications are based on discontinuous fibre arch...

This research presents a novel experimental approach to characterize the non-linear behaviour of hemp fibres, by combining standard tensile tests with a detailed strain analysis during tensile loading. First, the strength and Young's modulus distribution of technical hemp fibres of 78 different variants (fibre species and geographic location) were...

This paper describes how flax fibers were submitted to a thermal treatment to modify their wettability and sensitivity to liquid sorption. The wettability of untreated and treated fibers was obtained by measuring contact angles between the fibers and two test liquids, water and diiodomethane. Contact angle measurements were performed in a tensiomet...

Carbon Fiber-reinforced polymer (CFRP) composites have received considerable attention due to outstanding characteristics and wide applications in many fields such as aircraft and marine industries [1]. The strength of the adhesion between the reinforcing carbon fibers and the matrix plays a decisive role in determining the final mechanical propert...

The influence of moisture content in the environment during manufacture of a novel cobalt-free UP matrix reinforced with flax fibres, on the fibre-matrix adhesion was studied. Flax surface energy was experimentally determined by measuring contact angles on technical fibres, using the Wilhelmy technique and the acid-base theory. The mechanical stren...

INTRODUCTION The interaction between the fiber and the matrix has a significant effect on the properties of the composite since the load distribution efficiency at the interface is determined by the degree of adhesion between the components. This strong fiber-matrix adhesion has to be obtained by interfacial interactions, including mechanical inter...

Direct contact angle measurements were performed between different molten thermoplastics, polypropylene (PP), polyvinylidene fluoride (PVDF), and maleic anhydride-grafted polypropylene (MAPP) with different maleic anhydride content, on smooth glass fibres and smooth glass plates. The matrices were selected as model systems for the investigation of...

With the use of Liquid Composite Moulding (LCM) for composite manufacturing in the transportation industry, the complexity of part shapes and quality requirements have increased tremendously. There is thus a strong need to accurately control and understand liquid flow through porous preforms in order to minimise void formation in composite parts. C...

The interface between natural fibers and thermoplastic matrices is studied, in which fiber-matrix wetting analysis and interfacial adhesion are investigated to obtain a systematic understanding of the interface. In wetting analysis, the surface energies of the fibers and the matrices are estimated using their contact angles in test liquids. Work of...

This research studies the strength and Young's modulus distribution of technical hemp fibres of different varieties which were analysed using the Weibull distribution and digital image correlation analysis respectively. The fibre-matrix interfacial bond strength was characterized by the critical local value of interfacial shear stress, τ d. The dif...

Physical adhesion was experimentally determined by measuring contact angles with different liquids on bamboo and glass fibres, using the Wilhelmy technique, and by applying the acid–base theory for calculating the surface energy components and the theoretical work of adhesion. The mechanical strength of the interfaces was assessed by single fibre p...

Natural coir fibres are studied for use as reinforcement in composite materials. In order to efficiently use the fibres and understand the composite properties, the microstructure and the mechanical properties of coir fibres are investigated in this study. X-ray microtomography in SEM (SEM-CT) and SEM image analysis are used to examine the fibre in...

X-ray computed tomography is a non-destructive testing technique that is widely used in the composites industry for the characterization of the various structures within a material. In this work, the challenges of scanning natural elements such as flax fibres or pine cone will be listed. For this type of materials, it is essential to know the absor...

Physical adhesion was experimentally determined by measuring contact angles with different liquids on bamboo and glass fibers, using the Wilhelmy technique and by applying the acid-base theory for calculating the surface energy components and the theoretical work of adhesion. The mechanical strength of the interfaces was assessed by single fibre pu...

Natural fibres are a realistic and ecological alternative to synthetic fibres as reinforcement for polymer composite materials due to their low cost, environmental friendliness, natural abundance, and mechanical properties. The latter allows the design of composite materials to meet specific mechanical properties. For instance, bamboo exhibits a co...