Polymer Matrix Nanocomposites Fabricated with Copper Nanoparticles and Photopolymer Resin via Vat Photopolymerization Additive Manufacturing.

This investigation explores the fabrication of polymer matrix nanocomposites via additive manufacturing (AM), using a UV photopolymerization resin and copper nanoparticles (Cu-NPs) with vat photopolymerization 3D printing technology. The aim in this study is to investigate the mentioned materials in different formulations in terms of inexpensive processing, the property related variability, and targeting multifunctional applications. After the AM process, samples were post-cured with UV light in order to obtain better mechanical properties. The particles and resin were mixed using an ultrasonicator, and the particle contents used were 0.0, 0.5, and 1.0 wt %. The process used in this investigation was simple and inexpensive, as the technologies used are quite accessible, from the 3D printer to the UV curing device. These formulations were characterized with scanning electron microscopy (SEM) to observe the materials' microstructure and tensile tests to quantify stress-strain derived properties. Results showed that, besides the simplicity of the process, the mixing was effective, which was observed in the scanning electron microscope. Additionally, the tensile strength was increased with the UV irradiation exposure, while the strain properties did not change significantly.

Mechanical and Ballistic Properties of Epoxy Composites Reinforced with Babassu Fibers (Attalea speciosa).

The mechanical and ballistic performance of epoxy matrix composites reinforced with 10, 20, and 30 vol.% of babassu fibers was investigated for the first time. The tests included tension, impact, and ballistic testing with 0.22 caliber ammunition. The results showed an improvement in tensile strength, elastic modulus, and elongation with the addition of babassu fiber, and the 30 vol.% composite stood out. Scanning electron microscopy analysis revealed the fracture modes of the composites, highlighting brittle fractures in the epoxy matrix, as well as other mechanisms such as fiber breakage and delamination in the fiber composites. Izod impact tests also showed improvement with increasing babassu fiber content. In ballistic tests, there was an increase in absorbed energy. All composites surpassed plain epoxy by over 3.5 times in ballistic energy absorption, underscoring the potential of babassu fiber in engineering and defense applications.

Rice Husk with PLA: 3D Filament Making and Additive Manufacturing of Samples for Potential Structural Applications.

Additive manufacturing has garnered significant attention as a versatile method for fabricating green and complex composite materials. This study delves into the fabrication of polymer composites by employing polylactic acid (PLA) in conjunction with rice husk as a reinforcing filler. The filaments were made by an extruded filament maker and then were used to make tensile and impact samples by another extrusion technology, fused deposition modeling (FDM). The structural and morphological characteristics of the composite materials were analyzed using scanning electron microscopy SEM. Results show that both the filament and samples are very reliable in producing polymer parts with this rice husk solid waste. This research contributes to increasing materials' circularity and potentially creating a local social economy around rice production, where this waste is not much used.

Corrosion Study on Duplex Stainless Steel UNS S31803 Subjected to Solutions Containing Chloride Ions.

In the present work, the influence of a corrosive environment and temperature on the corrosion resistance properties of duplex stainless steel S31803 was evaluated. The corrosive process was carried out using solutions of 1.5% HCl (m/m) and 6% FeCl3 (m/m), at temperatures of 25 and 50 °C. The microstructure of UNS S31803 duplex stainless steel is composed of two phases, ferrite and austenite, oriented in the rolling direction, containing a ferrite percentage of 46.2% in the rolling direction and 56.1% in the normal direction. Samples, when subjected to corrosive media and temperature, tend to decrease their mechanical property values. It was observed, in both corrosive media, that with increasing test temperature, there is an increase in the corrosion rate, both uniform and pitting. The sample in HCl solution obtained a uniform corrosion rate of 0.85% at 25 °C and 0.92% at 50 °C and pitting rates of 0.77% and 1.47% at the same temperatures, respectively. When tested in FeCl3 solution, it obtained uniform corrosion of 0.0006% and 0.93% and pitting of 0.53% and 18.5%, at the same temperatures. A reduction in dissolution potentials is also noted, thus characterizing greater corrosion in the samples with increasing temperature.

Biocomposites of Cellulose Isolated from Coffee Processing By-Products and Incorporation in Poly(Butylene Adipate-Co-Terephthalate) (PBAT) Matrix: An Overview.

With its extensive production and consumption, the coffee industry generates significant amounts of lignocellulosic waste. This waste, primarily comprising coffee biomasses, is a potential source of cellulose. This cellulose can be extracted and utilized as a reinforcing agent in various biocomposites with polymer matrices, thereby creating high-value products. One such biodegradable polymer, Poly(butylene adipate-co-terephthalate) (PBAT), is notable for its properties that are comparable with low-density polyethylene, making it an excellent candidate for packaging applications. However, the wider adoption of PBAT is hindered by its relatively high cost and lower thermomechanical properties compared with conventional, non-biodegradable polymers. By reinforcing PBAT-based biocomposites with cellulose, it is possible to enhance their thermomechanical strength, as well as improve their water vapor and oxygen barrier capabilities, surpassing those of pure PBAT. Consequently, this study aims to provide a comprehensive review of the latest processing techniques for deriving cellulose from the coffee industry's lignocellulosic by-products and other coffee-related agro-industrial wastes. It also focuses on the preparation and characterization of cellulose-reinforced PBAT biocomposites.

Magnetic Nanoparticles in Biopolymer Fibers: Fabrication Techniques and Characterization Methods.

Hybrid nanocomposites combining biopolymer fibers incorporated with nanoparticles (NPs) have received increasing attention due to their remarkable characteristics. Inorganic NPs are typically chosen for their properties, such as magnetism and thermal or electrical conductivity, for example. Meanwhile, the biopolymer fiber component is a backbone, and could act as a support structure for the NPs. This shift towards biopolymers over traditional synthetic polymers is motivated by their sustainability, compatibility with biological systems, non-toxic nature, and natural decomposition. This study employed the solution blow spinning (SBS) method to obtain a nanocomposite comprising poly(vinyl pyrrolidone), PVA, and gelatin biodegradable polymer fibers incorporated with magnetic iron oxide nanoparticles coated with poly(acrylic acid), PAA2k, coded as γ-Fe2O3-NPs-PAA2k. The fiber production process entailed a preliminary investigation to determine suitable solvents, polymer concentrations, and spinning parameters. γ-Fe2O3-NPs were synthesized via chemical co-precipitation as maghemite and coated with PAA2k through the precipitation-redispersion protocol in order to prepare γ-Fe2O3-NPs-PAA2k. Biopolymeric fibers containing coated NPs with sub-micrometer diameters were obtained, with NP concentrations ranging from 1.0 to 1.7% wt. The synthesized NPs underwent characterization via dynamic light scattering, zeta potential analysis, and infrared spectroscopy, while the biopolymer fibers were characterized through scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. Overall, this study demonstrates the successful implementation of SBS for producing biopolymeric fibers incorporating iron oxide NPs, where the amalgamation of materials demonstrated superior thermal behavior to the plain polymers. The thorough characterization of the NPs and fibers provided valuable insights into their properties, paving the way for their potential applications in various fields such as biomedical engineering, environmental remediation, and functional materials.

Impact of Different Mineral Reinforcements on HDPE Composites: Effects of Melt Flow Index and Particle Size on Physical and Mechanical Properties.

The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

Influence of Test Method on the Determination of Tensile Strength Perpendicular to Grain of Timber for Civil Construction.

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test.

Poly (Ether-Ether-Ketone) for Biomedical Applications: From Enhancing Bioactivity to Reinforced-Bioactive Composites-An Overview.

The global orthopedic market is forecasted to reach US$79.5 billion by the end of this decade. Factors driving the increase in this market are population aging, sports injury, road traffic accidents, and overweight, which justify a growing demand for orthopedic implants. Therefore, it is of utmost importance to develop bone implants with superior mechanical and biological properties to face the demand and improve patients' quality of life. Today, metallic implants still hold a dominant position in the global orthopedic implant market, mainly due to their superior mechanical resistance. However, their performance might be jeopardized due to the possible release of metallic debris, leading to cytotoxic effects and inflammatory responses in the body. Poly (ether-ether-ketone) (PEEK) is a biocompatible, high-performance polymer and one of the most prominent candidates to be used in manufacturing bone implants due to its similarity to the mechanical properties of bone. Unfortunately, the bioinert nature of PEEK culminates in its diminished osseointegration. Notwithstanding, PEEK's bioactivity can be improved through surface modification techniques and by the development of bioactive composites. This paper overviews the advantages of using PEEK for manufacturing implants and addresses the most common strategies to improve the bioactivity of PEEK in order to promote enhanced biomechanical performance.

Babassu Coconut Fibers: Investigation of Chemical and Surface Properties (Attalea speciosa.).

To complement previous results, an analysis of the chemical and morphological properties of babassu fibers (Attalea speciosa Mart. ex Spreng.) was conducted in order to evaluate their potential as reinforcements in the production of composites with epoxy matrix. The diameter distribution was analyzed in a sample of one hundred fibers, allowing the verification of its variation. The determination of the chemical properties involved experimental analyses of the constituent index and X-ray diffraction. The diffractogram was used to calculate the crystallinity index and the microfibril angle, which are crucial parameters that indicate the consistency of the mechanical properties of babassu fibers and the feasibility of their use in composites. The results revealed that babassu fiber has a chemical composition, with contents of 28.53% lignin, 32.34% hemicellulose, and 37.97% cellulose. In addition, it showed a high crystallinity index of 81.06% and a microfibril angle of 7.67°. These characteristics, together with previous results, indicate that babassu fibers have favorable chemical and morphological properties to be used as reinforcements in composites, highlighting its potential as an important material for applications in technology areas.

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review.

The search for alternative materials to replace ordinary Portland cement has been the object of work that enhances the investigation of the use of pozzolanic materials and the reduction of the carbon footprint with supplementary cementitious materials. However, not all materials are available to meet the large-scale demand for cement replacement. A relevant exception is the calcined clay, a material found worldwide that, when subjected to appropriate heat treatment, presents pozzolanic reactivity and can be used as a supplementary material to cement. This review presents, through a systematic search, methods for measuring the pozzolanic reactivity of calcined clays, namely, direct, indirect, qualitative, quantitative, chemical and physical methods such as electrical conductivity (Lùxan), the force activity index, the modified Chapelle, R3, Frattini test, thermal analysis, X-ray diffraction and X-ray fluorescence spectrometry. The most usual methods to assess the pozzolanic reactivity of calcined clays were exposed and analyzed. It should be pointed out that there is greater use of the Frattini and modified Chapelle methods as well as the analysis of the mechanical strength behavior of the material in cementitious matrices. X-ray diffraction and thermal analysis were exposed as the most used correlation methods but it was also concluded that different tests are needed to generate accurate results.

A Review of the Use of Coconut Fiber in Cement Composites.

The use of plant fibers in cementitious composites has been gaining prominence with the need for more sustainable construction materials. It occurs due to the advantages natural fibers provide to these composites, such as the reduction of density, fragmentation, and propagation of cracks in concrete. The consumption of coconut, a fruit grown in tropical countries, generates shells that are improperly disposed of in the environment. The objective of this paper is to provide a comprehensive review of the use of coconut fibers and coconut fiber textile mesh in cement-based materials. For this purpose, discussions were conducted on plant fibers, the production and characteristics of coconut fibers, cementitious composites reinforced with coconut fibers, cementitious composites reinforced with textile mesh as an innovative material to absorb coconut fibers, and treatments of coconut fiber for improved product performance and durability. Finally, future perspectives on this field of study have also been highlighted. Thus, this paper aims to understand the behavior of cementitious matrices reinforced with plant fibers and demonstrate that coconut fiber has a high capacity to be used in cementitious composites instead of synthetic fibers.

Characterization of Artificial Stone Produced with Blast Furnace Dust Waste Incorporated into a Mixture of Epoxy Resin and Cashew Nut Shell Oil.

The demand for materials with improved properties and less negative impact on the environment is growing. Artificial stones are examples of these materials produced with up to 90% of particulate material joined by a binder. This article evaluates the physical and mechanical properties of two artificial stones produced with processing steel residue (blast furnace dust waste) and quartz powder. Two binders were used: pure epoxy resin, denoted as ASPB100, or a mixture of 70 wt% epoxy resin with 30 wt% cashew nut shell oil, denoted as ASPB7030. The process took place under vibration, compression (3 MPa/20 min and 90 °C) and vacuum (80 Pa). ASPB100 showed water absorption of 0.07%, while for ASPB7030, it was 0.54%. They were classified as having high mechanical strength associated with bending stress values equal to 32 and 25 MPa, respectively. Stain resistance indicated that both artificial stones had their stains removed with the tested cleaning agents. In this way, the novel artificial stones produced are sustainable alternatives for the application of blast furnace waste and cashew nut shell oil, reducing their negative impacts on the environment.

Assessment of Hydrothermal Treatment Effects on Coir Fibers for Incorporation into Polyurethane Matrix Biocomposites Derived from Castor Oil.

The incorporation of natural lignocellulosic fibers as reinforcements in polymer composites has witnessed significant growth due to their biodegradability, cost-effectiveness, and mechanical properties. This study aims to evaluate castor-oil-based polyurethane (COPU), incorporating different contents of coconut coir fibers, 5, 10, and 15 wt%. The investigation includes analysis of the physical, mechanical, and microstructural properties of these composites. Additionally, this study evaluates the influence of hydrothermal treatment on the fibers, conducted at 120 °C and 98 kPa for 30 min, on the biocomposites' properties. Both coir fibers (CFs) and hydrothermal-treated coir fibers (HTCFs) were subjected to comprehensive characterization, including lignocellulosic composition analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The biocomposites were subjected to water absorption analysis, bending tests, XRD, SEM, FTIR, and TGA. The results indicate that the 30 min hydrothermal treatment reduces the extractive content, enhancing the interfacial adhesion between the fiber and the matrix, as evidenced by SEM. Notably, the composite containing 5 wt% CF exhibits a reduced water absorption, approaching the level observed in pure COPU. The inclusion of 15 wt% HTCF results in a remarkable improvement in the composite's flexural strength (100%), elastic modulus (98%), and toughness (280%) compared to neat COPU. TGA highlights that incorporating CFs into the COPU matrix enhances the material's thermal stability, allowing it to withstand temperatures of up to 500 °C. These findings underscore the potential of CFs as a ductile, lightweight, and cost-effective reinforcement in COPU matrix biocomposites, particularly for engineering applications.

Ballistic Behavior of Epoxy Composites Reinforced with Amazon Titica Vine Fibers (Heteropsis flexuosa) in Multilayered Armor System and as Stand-Alone Target.

Seeking to improve personal armor equipment by providing mobility and resistance to penetration, this research aimed to explore the potential of sustainable materials in order to assess their ability in ballistic applications. Titica vine fibers (TVFs) extracted from aerial roots of Heteropsis flexuosa from the Amazon region were incorporated at 10, 20, 30, and 40 vol% into an epoxy matrix for applications in ballistic multilayered armor systems (MASs) and stand-alone tests for personal protection against high-velocity 7.62 mm ammunition. The back-face signature (BFS) depth measured for composites with 20 and 40 vol% TVFs used as an intermediate layer in MASs was 25.6 and 32.5 mm, respectively, and below the maximum limit of 44 mm set by the international standard. Fracture mechanisms found by scanning electron microscopy (SEM) attested the relevance of increasing the fiber content for applications in MASs. The results of stand-alone tests showed that the control (0 vol%) and samples with 20 vol% TVFs absorbed the highest impact energy (Eabs) (212-176 J), and consequently displayed limit velocity (VL) values (213-194 m/s), when compared with 40 vol% fiber composites. However, the macroscopic evaluation found that, referring to the control samples, the plain epoxy shattered completely. In addition, for 10 and 20 vol% TVFs, the composites were fragmented or exhibited delamination fractures, which compromised their physical integrity. On the other hand, composites with 30 and 40 vol% TVFs, whose Eabs and VL varied between 166-130 J and 189-167 m/s, respectively, showed the best physical stability. The SEM images indicated that for composites with 10 and 20 vol% TVFs, the fracture mode was predominantly brittle due to the greater participation of the epoxy resin and the discrete action of the fibers, while for composites with 30 and 40 vol% TVFs, there was activation of more complex mechanisms such as pullout, shearing, and fiber rupture. These results indicate that the TVF composite has great potential for use in bulletproof vests.

Periquiteira (Cochlospermum orinocense): A Promising Amazon Fiber for Application in Composite Materials.

Natural lignocellulosic fibers (NLFs) have in recent decades appeared as sustainable reinforcement alternatives to replace synthetic fibers in polymer composite material applications. In this work, for the first time, the periquiteira (Cochlospermum orinocense), a lesser known NLF from the Amazon region, was analyzed for its density and, by X-ray diffraction (XRD), to calculate the crystallinity index as well as the microfibrillar angle (MFA), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron analysis (SEM) and tensile strength. The apparent density found for the periquiteira fiber was 0.43 g/cm3, one of the NLF's lowest. XRD analysis indicated a crystallinity index of 70.49% and MFA of 7.32°. The TGA disclosed thermal stability up to 250 °C. The FTIR analysis indicated the presence of functional groups characteristic of NLFs. The SEM morphological analysis revealed that the periquiteira fiber presents fine bundles of fibrils and a rough surface throughout its entire length. The average strength value of the periquiteira fiber was found as 178 MPa. These preliminary results indicate that the periquiteira fiber has the potential to be used as a reinforcing agent in polymeric matrices and can generate a lightweight composite with excellent mechanical properties that can be used in various industrial sectors.

Alkaline Treatment Investigation for Sedge Fibers (Cyperus malaccensis): A Promising Enhancement.

Natural fibers have some advantages in comparison to synthetic fibers, especially because they are more environmentally friendly. For this reason, using them as a reinforcement for polymeric matrices is growing exponentially. However, they present the disadvantage of having the hydrophilic nature, which strongly reduces the interface interaction. Sedge fibers have been investigated when reinforcing an epoxy matrix in terms of ballistic properties and mechanical performance. Aiming to enhance the fiber-matrix interface, an alkali treatment was proposed. The group conditions were divided into three NaOH concentrations (3%, 5%, and 10%), as well as the three periods of immersion (24, 48, and 72 h). Therefore, nine different conditions were investigated in terms of their thermal behaviors, chemical structures, physical structures, and morphological aspects. Based on TGA curves, it could be noticed that treatments related to 3% NaOH for 24 h and 48 h exhibited better thermal stability properties. For the time of 48 h, better thermal stability with for a decay of the thermal DSC curve was shown for all treatment conditions. The FTIR spectra has shown a reduction of waxes for higher NaOH concentrations. The XRD diffractogram exhibited an increase in the crystallinity index only for 5% NaOH and an immersion time of 48 h. The morphological aspects of fibers treated with 5% and 10% of NaOH have shown that the treatments have damaged the fiber, which highlighted the crystallinity index reductions.

Thermal Behavior of Curaua-Aramid Hybrid Laminated Composites for Ballistic Helmet.

Hybrid composites are expanding applications in cutting-edge technology industries, which need materials capable of meeting combined properties in order to guarantee high performance and cost-effectiveness. This original article aimed for the first time to investigate the hybrid laminated composite thermal behavior, made of two types of fibers: synthetic Twaron® fabric and natural curaua non-woven mat, reinforcing epoxy matrix. The composite processing was based on the ballistic helmets methodology from the North American Personal Armor System for Ground Troops, currently used by the Brazilian Army, aiming at reduced costs, total weight, and environmental impact associated with the material without compromising ballistic performance. Thermal properties of plain epoxy, aramid fabric, and curaua mat were evaluated, as well as the other five configurations of hybrid laminated composites. These properties were compared using thermogravimetric analysis (TGA) with its derivative (DTG), differential thermal analysis (DTA), and thermomechanical analysis (TMA). The results showed that the plain epoxy begins thermal degradation at 208 °C while the curaua mat at 231 °C and the aramid fabric at 477 °C. The hybrid laminated composites curves showed two or three inflections in terms of mass loss. The only sample that underwent thermal expansion was the five-aramid and three-curaua layers composite. In the third analyzed temperature interval, related to the glass transition temperature of the composites, there was, in general, an increasing thermal stability behavior.

Ballistic Performance, Thermal and Chemical Characterization of Ubim Fiber (Geonoma baculifera) Reinforced Epoxy Matrix Composites.

The search for unexplored natural materials as an alternative to synthetic components has driven the development of novel polymeric composites reinforced with environmentally-friendly materials. Natural lignocellulosic fibers (NLFs) have been highlighted as potential reinforcement in composite materials for engineering applications. In this work, a less known Amazonian fiber, the ubim fiber (Geonoma baculifera), is investigated as a possible reinforcement in epoxy composites and was, for the first time, thermally characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, its chemical structure was elucidated by Fourier transform infrared spectroscopy (FTIR). Ballistic tests were also performed against the threat of a 7.62 mm high-speed lead projectile. The results were statistically analyzed by the Weibull statistical analysis method. FTIR analysis showed the functional groups normally found for NLFs highly rich in cellulose, hemicellulose, and lignin. The TGA/DTG results showed the onset of thermal degradation for the composites (325~335 °C), which represents better thermal stability than isolated ubim fiber (259 °C), but slightly lower than that of pure epoxy (352 °C). The DSC results of the composites indicate endothermic peaks between 54 and 56 °C, and for the ubim fibers, at 71 °C. Ballistic tests revealed higher energy absorption in composites with lower fiber content due to the more intense action of the brittle fracture mechanisms of the epoxy resin, which tended to dissipate more energy. These failure mechanisms revealed the presence of river marks, cracks, and broken fibers with a detachment interface. These results may contribute to the production of ubim fiber-reinforced composites in engineering applications, such as ballistic armors.

Use of Yarn and Carded Jute as Epoxy Matrix Reinforcement for the Production of Composite Materials for Application in the Wind Sector: A Preliminary Analysis for the Manufacture of Blades for Low-Intensity Winds.

The development of wind turbines for regions with low wind speeds imposes a challenge to the expansion of the corresponding energy generation capacity. The present work consists of an evaluation of the potential carded jute fiber and jute yarn to be used in the construction of a wind blade for regions of low wind intensity. The fibers used were supplied by Company Textile of Castanhal (Castanhal-Para-Brazil) and used in the study without chemical treatment in the form of single-filament fibers and yarns with a surface twist of 18.5°. The composites were produced through the resin infusion technique and underwent tensile and shear tests using 120-Ohm strain gauges and a blade extensometer to obtain the Young's modulus. In the analysis of the results, the ANOVA test was applied with a 0.05 significance level, followed by Tukey's test. The results showed that long, aligned jute fibers can be a good option for laminated structures applied in composites for small wind turbine blades.