Natural Lignocellulosic Fibers Research Articles

Thermochemical and structural characterization of raffia fiber fabric (Raphia vinifera) from the Amazon region

Raffia, a natural lignocellulosic fiber (NLF) extracted from the leaf of the Raphia vinifera palm tree was a long time introduced to the Amazon region. A thermochemical and structural evaluation of the raffia fiber fabric was conducted in the current study. Characterization of the fabric fibers was done using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), lignocellulosic analysis and scanning electron microscopy (SEM). The thermogravimetric analysis showed a loss of moisture at 52.0 °C and the beginning of degradation at 245 °C. During DSC analysis, three peaks were detected: one endothermic peak at 56 °C and two exothermic peaks at 298 and 336 °C, which were linked to the materials in the fibers. The FTIR showed bands indicating molecular vibrations of functional groups present in the constituents of the NLF, like cellulose, hemicellulose, and lignin. Moreover, the raffia fiber fabric exhibited a CI of 66.04% and an MFA of 7.24° as shown in the XRD pattern. The moisture content of the raffia fabric was measured at 9.47%. The density of the raffia fabric was measured at 0.95 g/cm³. Furthermore, it has been discovered a chemical composition with 25% lignin, 14% hemicellulose, and 52% cellulose. Moreover, SEM images revealed that the raffia fiber fabric displays surface porosity throughout its entirety. Given the results mentioned above, raffia fabric fibers show great promise for use in engineering applications, as their properties are comparable to those of other NLF composites used in polymer reinforcement.

Influence of drying temperature on coconut-fibers

The use of natural fibers in cementitious composites has been gaining prominence in engineering. The natural lignocellulosic fibers (NLFs) used in these composites have advantages such as reduced density, reduced fragmentation and concrete cracking, thus improving flexural performance and durability. Coconut-fiber is one of those natural fibers and its use presents technical, ecological, social and economic benefits, as it is improperly disposed of, representing a large waste of natural resources, in addition to causing environmental pollution.. Thus, composites reinforced with natural fibers are promising materials for the construction industry, as in addition to meeting the sustainability of buildings, there will also be a reduction in urban solid waste generated and gains for structures with the use of environmentally friendly materials that meet to active efforts and with greater durability. This work aims to evaluate the tensile behavior of green coconut-fibers subjected to different drying temperatures through chemical, thermal (TG/DSC), morphological, visual and mechanical analysis. Drying temperatures of 70 °C, 100 °C and 130 °C were analyzed and the results indicated that the drying temperature at 70 °C was satisfactory, providing fiber-reinforced composites with good tensile strength, combined with good ductility.

Amazon Natural Fibers for Application in Engineering Composites and Sustainable Actions: A Review

The Amazon rainforest, spanning multiple countries in South America, is the world’s largest equatorial expanse, housing a vast array of relatively unknown plant and animal species. Encompassing the planet’s greatest flora, the Amazon offers a tremendous variety of plants from which natural lignocellulosic fibers (NLFs) can be extracted. In this century, NLFs, which have long been utilized by indigenous populations of the Amazon, have garnered interest as potential reinforcements for composites, whether polymer- or cement-based, in various technical applications such as packaging, construction, automotive products, and ballistic armor. A comparison with synthetic materials like glass, carbon, and aramid fibers, as well as other established NLFs, highlights the cost and specific property advantages of Amazon natural fibers (ANFs). Notably, the sustainable cultivation and extraction of ANFs, as alternatives to deforestation and livestock pasture, contribute to the preservation of the Amazon rainforest. This review article provides a comprehensive examination of recent studies directly related to ANF-reinforced polymer matrix composites. The specific advantages, proposed applications, and reported challenges are highlighted, shedding light on the potential of these unique natural fibers.

Helianthus Annuus L. Comparison Of The Properties Of Fibers Obtained From The Plant By Methods of Decortication And Retting

A large amount of sunflower production is carried out in our country. The 2,500,000 tons of sunflower stalks that appeared after production pose a problem for our farmer. In order to clean up this environmental problem from the field, sunflower stalks are destroyed by burning to warm up in winter, broken down and mixed into the soil, or burned after harvesting. It is thought that by obtaining qualified, ecological and naturally decomposing sunflower fiber from the stem of the sunflower plant, which is an agricultural waste, it can increase the added value of agricultural products and contribute to the protection of the environment. In this study, the anatomical characteristics of the stem of the sunflower plant were determined, and natural lignocellulosic fibers were obtained from the sunflower stem by retting and decortication methods (fresh stem, dried stem). Various physical, chemical and mechanical properties of these fibers have been measured. For this purpose, FTIR (Fourier Transform Infrared Spectroscopy) analysis, XRD (X-Ray Diffractometer) analysis and SEM (Scanning Electron Microscope) analysis were applied to the fibers obtained by different methods. Thermal analyses were performed by TG-DTA (Thermogravimetric) analysis. In addition, fiber strength, fiber fineness, fiber length and color measurements were made. The chemical content of the obtained fibers (pectin, lignin, cellulose, hemicellulose) was determined. The properties of the fibers were compared using the obtained data. As a result of the study, it has been seen that the characteristic properties of the sunflower fibers obtained by the retting method are better. It has been determined that the elemental, thermal and crystal structures of the fibers obtained by different methods are similar. It was concluded that sunflower fiber will not be spun as a yarn, but can be used as a natural polymeric composite reinforcement material.

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.

Heat insulating jute-reinforced recycled polyethylene and polypropylene bio-composites for energy conservation in buildings

The development of jute-reinforced recycled polyethylene (PE) and polypropylene (PP) bio-composites using a heat-pressed molding technique and the feasibility of using them as thermal-insulating panels in building interiors have been studied in the current research. Lignocellulosic natural jute fibers of different volume fractions were employed as reinforcement to fabricate recycled PP and PE composites, and their thermal and mechanical characteristics were investigated for the intended applications. The developed jute-PP composites showed a higher tensile (75.16 MPa) and flexural (121.13 MPa) strength compared to jute-PE with the tensile and flexural strength of 55.62 MPa and 74.53 MPa, respectively, which is attributed to the better tensile strength of PP and its superior interfacial bonding with the jute fiber than PE. The fractographic investigation also confirmed the desired interfacial attachment of reinforcement and recycled polymers in the composite structure. The heat barrier characteristics, including low thermal conductivity (0.2694 W/m.K and 0.1852 W/m.K for jute-PE and jute-PP, respectively) and enhanced conductive and radiative heat resistance with increased volume fraction of jute fiber, specified adequate heat barrier performance of the developed composites for building thermal applications. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) study revealed comparable thermal stability of both composites at elevated temperatures. Additionally, due to reduced interfacial vacuity and the existence of hydrophobic PE and PP, composite samples demonstrated very low water absorption with time, which suggested the potentiality of utilizing them as durable heat-insulating materials in building structures. Accordingly, the fabrication of thermal-insulating engineered recycled biocomposites and their application in designing green buildings can significantly contribute to reducing the global carbon footprint associated with thermal energy consumption of buildings and alleviating the growing environmental problems of plastic waste by utilizing them as matrix polymer in fiber-reinforced composites.

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.

MECHANICAL BEHAVIOR OF HIGH-DENSITY POLYETHYLENE REINFORCED WITH GRAPHENE NANOPLATELETS AND JUTE FABRIC

Owing to sustainable characteristics, natural lignocellulosic fibers (FNLs) and graphene nanoplatelets (GNP)-reinforced composites are currently seeing applications in a wide range of industrial fields. Thus, in the present work, the mechanical, and flexural properties of high-density polyethylene (HDPE) reinforced with 0, 0.10, 0.25, and 0.50 wt.% of GNP combined with 50 vol.% of Juta fabric were investigated. In particular, the Juta/HDPE/0.25%GNP composite outperformed the strength of those described in the literature, even some with higher GNP. Enhancements of 38% were observed for the composite’s flexural modulus as compared to the GNP-free Juta/HDPE composite. Regarding the tensile properties, the ductility of the Juta/HDPE/0.25%GNP was increased by 112% when compared to the Juta/HDPE. Moreover, the toughness of the Juta/HDPE/0.25%GNP was 161% superior to the Juta/HDPE composite. SEM analysis of the fracture surfaces showed that, as GNP concentration rises, the fracture mechanisms change from shear band to a complex mixture of fibrillation, tearing, and crazing. Consequently, the results reveal the novel Juta/HDPE/0.25%GNP nanocomposite as a promising material for engineering applications.

Extraction and Characterization of Cellulosic Fibers from Jenfokie and Doby Stems: Effect of Extraction Methods on Physicochemical, Mechanical, and Thermal Properties

ABSTRACT This experimental study aims to explore natural lignocellulosic fibers from Jenfokie and Doby plants. The effect of the fiber (water-retted and non-retted) extraction methods on physical, mechanical, thermal, chemical, and crystallinity properties were experimentally investigated for fibers collected from the eastern highlands of Ethiopia. The chemical composition (cellulose, hemicellulose, lignin, extractives, etc.) was determined after different treatment processes. The tensile strength maximum of up to 72 cN/tex and 56 cN/tex, and cellulose content up to 85% and 81% were obtained for Jenfokie and Doby retted extracted fibers, respectively. There was small difference lignin extracted by Klason method and the alkaline hydrogen peroxide (APH) method. Each step-wise extracted fiber was characterized to cognize the intrinsic changes during the multi-step extraction process. The diameters were determined by Optical Microscope (OM), the removal of non-cellulosic materials by Fourier Transform Infrared (FT-IR) spectroscopy, the thermal stability (up to 375°C) by thermogravimetry (TGA), and the crystallinity index (up to 73%) by using X-ray Diffraction (XRD). An improvement in cellulose content, density, moisture absorption, tensile strength, thermal stability, and crystallinity of Jenfokie (unstudied or new) and Doby plant retted fibers would be promising for composite and textile materials.

Mechanical Properties Optimization of Hybrid Aramid and Jute Fabrics-Reinforced Graphene Nanoplatelets in Functionalized HDPE Matrix Nanocomposites.

Natural lignocellulosic fibers (NLFs) have been used as a reinforcement for polymer matrix composites in the past couple of decades. Their biodegradability, renewability, and abundance make them appealing for sustainable materials. However, synthetic fibers surpass NLFs in mechanical and thermal properties. Combining these fibers as a hybrid reinforcement in polymeric materials shows promise for multifunctional materials and structures. Functionalizing these composites with graphene-based materials could lead to superior properties. This research optimized the tensile and impact resistance of a jute/aramid/HDPE hybrid nanocomposite by the addition of graphene nanoplatelets (GNP). The hybrid structure with 10 jute/10 aramid layers and 0.10 wt.% GNP exhibited a 2433% increase in mechanical toughness, a 591% increase in tensile strength, and a 462% reduction in ductility compared to neat jute/HDPE composites. A SEM analysis revealed the influence of GNP nano-functionalization on the failure mechanisms of these hybrid nanocomposites.

Extraction and Characterization of Sponge Gourd Outer Skin Fiber

ABSTRACT Plant-derived natural fibers have recently been used as a promising reinforcement in polymer matrix composites. Fibers from the inner sponge of the luffa cylindrica fruit have been the subject of several studies as reinforcement in various polymer resins. However, no research has been done on the Sponge Gourd Outer Skin Fiber (SGOSF). The present work is aimed to extract and characterize the chemical and physical properties of novel natural lignocellulosic fiber obtained from the outer skin (waste material) of the matured Luffa Cylindrica plant fruit. Characteristic studies on chemical composition, chemical structure, chemical compounds, thermal stability, and morphology of luffa cylindrica outer skin fibers (SGOSF) were investigated. The results revealed that SGOSF had cellulose (81.69 wt. %), lignin (10.14 wt. %), wax (0.22 wt.%), and ash content (1.18 wt. %). The density of the SGOSF was reported as 1.394 g/cm3. Thermal study results indicate SGOSF were withstanding the temperature up to 320°C. Fourier transform infrared analysis (FTIR) was done to determine the molecular structure of SGOSFs. The SGOSFs show tensile strength of 438.5 MPa. These results revealed that SGOSFs could be a sound reinforcement in the polymer matrix composites for various applications.

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.

Design of a friction material for brake pads based on rice husk and its derivatives

Commercial vehicle brake pads play an important role in the environmental impact caused by road transport. Their complex raw material requirements and increasingly prevalent contribution to traffic pollution is forcing the industry to look for alternative solutions. Natural lignocellulosic fibers have already been investigated as sustainable brake pad ingredients, and while braking performance results appear promising, important characteristics such as wear and particulate matter emission are either deteriorated or outright neglected. In this study, rice husk, a byproduct of the agricultural industry, is investigated as possible environmentally friendly natural ingredient. Friction material samples based on a commercial formulation were modified by adding different percentages of both rice husk and rice husk ash, the product of a thermal treatment of the former, and then tested with a modified pin-on-disc tribometer. The experimental setup included collecting instruments for emitted wear particles. 6 to 12 wt% of rice husk showed preservation of the braking performance whilst possibly improving wear and emission characteristics of the friction material. Higher amounts of modifications led to deterioration of tribological properties. Overall, this investigation suggest that limited yet substantial amounts of rice husk could successfully substitute conventional filler ingredients in brake pad formulations, as an effective approach in lowering their environmental impact.

Mechanical behavior and physicochemical modifications in lignosulfonate-treated fique (Furcraea Andina) fibers

One of the most frequent problems in biocomposites is the physical/chemical incompatibility between natural lignocellulosic fibers (NLF) and the matrix. Physical and/or chemical treatments are the most common approach to improve interface properties. Seeking for environmentally friendly treatments, lignosulfonates (LSs) have been considered for surface modification of NLF due to their amphiphilic properties. Thus, the objective of the present work is to evaluate the influence of sodium LS (SLS) treatment protocols in the properties and mechanical behavior of fique (Furcraea Andina) fibers. X-ray diffraction (XRD), Thermogravimetric (TGA) and spectroscopic (FTIR) analyzes were performed, as well as optical microscopy, scanning electron microscopy (SEM), fiber-diameter measurements and tensile tests. The results showed efficient surface cleaning from extractives and absorption of saline and aromatic components from SLS. Partial removal of lignin and hemicellulose was observed as well, manifested by an increasing in fiber crystallinity, decreasing in the intensity of the characteristic bands of C=O (acetyl and ester) and p-hydroxy-phenyl, and displacement in the temperature of cellulose pyrolysis to lower temperatures. These phenomena were stronger in the fibers with longer exposures to SLS. The SLS treatment protocols produce a narrower strength distribution, improving the reliability of the fibers relative to its mechanical behavior.

Assessment of process integration approach for coir biosoftening and lignin‐modifying enzyme production from agro residues

AbstractLignin present in the inner core of natural lignocellulosic fibers is preferably removed for use in the textile industry as it hinders fiber spinnability. This study focuses on integrating the bioprocessing of agro residues and a natural fiber source (coir) for the effective production of lignin‐modifying enzymes while simultaneously softening the natural fibers. The lignin content in the raw fibers (42.17%) could be reduced by 14–31% by treating them with Phanerochaete chrysosporium for 30 days in the presence of agro waste, such as paddy straw, groundnut husk, corn husk, coir pith, sugarcane bagasse, saw dust and coconut leaf. Among the lignocellulosic wastes tested, P. chrysporium‐fermented groundnut husk with coir produced the maximum yield of lignin‐modifying enzymes (lignin peroxidase, 2.05 U mg−1; manganese peroxidase, 7.50 U mg−1; laccase, 0.43 U mL−1), while the tensile strength of the fiber was decreased by 9.9% compared with the raw fiber (110.14 MPa) on 30 days of incubation. Similarly, SB dust demonstrated good lignin‐modifying enzyme activity (lignin peroxidase, −1.57 U mg−1; manganese peroxidase, 8.14 U mg−1; and laccase, 0.35 U mg−1) as well as the tensile strength of the coir also being increased. A reduction in flexural rigidity owing to delignification was observed and hence a minimum 16% increase in softness was achieved in the integrated process. Our study presents an efficient strategy that exploits low‐cost agro residues for enzyme production and generates bio‐softened coir of acceptable quality in the export and domestic markets. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd.

Ballistic performance of Cyperus malaccensis sedge fibers reinforcing epoxy matrix as a standalone target

A growing demand for research about ballistic armor shields follows the increase of violence around the world. Ultimately, different composite materials with polymeric matrices have already presented the minimum performance as an individual protection required with cheaper and lower density, such as those reinforced with natural lignocellulosic fiber (NLF). However, with of vegetal species around the world, unknown fibers might present promising mechanical behavior. Thus, a ballistic investigation of an epoxy matrix composite owning a novel Cyperus malaccensis (CM) fibers as a reinforcement is proposed. The tests explored the limit and residual velocity of composites in three different conditions, 10, 20, and 30 vol%. Afterwards, fractured surfaces were analyzed in a scanning electron microscopy (SEM) for a deeper investigation of the failure mechanism. From the tests, it could be observed that the plates condition of 20 vol% of CM fibers attained the highest value of energy absorption (222.11 J) and limit velocity (231.34 m/s), although the ones reinforced with 30 vol% showed a more complete physical integrity. For this group, the SEM micrographs presented the mechanisms of failure related to delamination and fiber rupture. The 10 and 20 vol% reinforced plates presented a slight difference in residual velocity (810.27 and 808.37 m/s, respectively).

Evaluation of the density, mechanical, thermal and chemical properties of babassu fibers (Attalea speciosa.) for potential composite reinforcement

The properties of babassu (Attalea speciosa.) fiber was for the first time investigated for potential engineering application such as reinforcement for matrix composites. The diameter distribution of babassu fibers was analyzed and found to be associated with significant variation in fiber density and mechanical properties. Additionally, thermogravimetric and Fourier transform infrared spectrometry (FTIR) analyses were performed. The studied Weibull statistical method was used to analyze the acquired data. The surface morphology of the fibers was studied by scanning electron microscopy. From the diameter ranges, it was possible to confirm that the thinner fibers have higher values of density and mechanical properties, which was attributed to their lower presence of defects. The diameter range was found between of 0.18 and 0.47 mm, and the corresponding densities were 0.79 and 0.27 g/cm³ respectively. Furthermore, the maximum tensile strength found was 100.76 MPa with an elastic modulus of 6.33 GPa and an elongation of 2.98%. Thermogravimetric analyses revealed a three-step mass loss, the main one being the second where the fiber loses 69% of the mass at a temperature of 382 °C. The FTIR analysis showed a similarity with the bands generally found in the literature for natural lignocellulosic fibers.

Structure and mechanical behavior of lignosulfonate-treated piassava (Attalea funifera) fibers

The use of natural lignocellulosic fiber (NLF) biocomposites for the construction industry has been growing over the years, due to technical and environmental advantages. However, fiber-matrix incompatibility remains a major challenge. Various surface treatments have been investigated to improve fiber-matrix bonding, including sodium lignosulfonate (SLS), a potentially effective and environmentally friendly chemical. In this study, SLS treatment protocols were applied to piassava fibers to evaluate their influence on the fibers. Thermogravimetric Analysis (TG/DTG), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM/EDS), Fourier-transform Infrared Spectroscopy (FTIR), moisture absorption measurements and tensile tests were performed to characterize the modifications. Results demonstrated, for the first time, the efficiency of SLS to remove extractives from the piassava surface. In general, partial degradation of the cellulosic structure was observed, noticeable by the slight drop in crystallinity index (from 42.80 to 39.82%), and an increase in the TG residual mass (from 21.35 to 31.90%), along with changes in DTG curves. However, a particular SLS treatment using ultrasonic bath was able to fully clean the surface preserving the cellulosic structure, and increasing the strength of fibers (from 386 ± 140 MPa to 524 ± 126 MPa).

Extraction and characterization of novel natural lignocellulosic fibers from Malva sylvestris L.

The main goal of this study is to characterize natural lignocellulosic fibers extracted from Malva Sylvestris. The experimental approach used is consisted to analyze the morphological, physical, chemical, thermal and mechanical characteristics of Malva sylvistris fibers. The stem anatomy showed that the bark of Malva is rich in fiber cells. Based on ATR-FTIR and X-ray analysis, the obtained results illustrated that the fiber contained mainly cellulose, hemicellulose and lignin. The crystallinity index of fiber is about 55.12 %, which indicated a high cellulose content. The Thermo-gravimetric analysis (TGA) analysis test point out that Malva Sylvestris fibers are thermally stable until 225°C and an apparent activation energy about of 111 kJ.mol−1 was recorded. Tensile strength of Malva fibers is about of 236.64 ± 93.33 MPa whilst its young’s modulus is about of 26.07 ± 5.14 GPa. In view of the dispersion in the obtained experimental results, the latter were analyzed using the Weibull statistical laws with two parameters.

Carnauba leaf fibers: correlation among diametrical variation, physical and mechanical properties

The variability of properties presented by natural lignocellulosic fibers (NLFs) is an important issue to highlight, since such inconsistencies in their characteristics put them at a disadvantage when comparing them to synthetic materials. It is important to point out that the application of methodologies that make it possible to predict the behavior of NLFs in the face of mechanical stress is essential for the use of these materials in engineering applications. For this, the present study proposes to evaluate the influence of the carnauba fibers (Copernicia prunifera) morphology in the properties presented by these materials. Optical microscopy (OM) was applied to determine the cross-section and diametrical variation of the fibers, enabling the evaluation of density by Archimedes method according to the mean diameter of the fibers. The mechanical properties were evaluated by tensile testing and the data were acquired by Weibull analysis. The morphological aspects of the longitudinal and cross-sections of the fibers were evaluated with scanning electron microscopy (SEM). The fibers had an average density of 1.13 ± 0.22 g/cm3, with diameter intervals ranging from 0.31 to 1.21 mm. The fibers have reasonable mechanical properties, with an average tensile strength of 64.7 ± 40.9 MPa, Young's modulus of 1.37 ± 0.80 GPa and elongation of 5.59 ± 1.60%. The SEM micrographs highlighted the defects present on the outer surface of the fiber as well as in the cross-section. There was a high potential for the use of carnauba fibers in the manufacture of polymer matrix composites.