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Identification of archaeological and historical textile fibres is important because it gives insight into resource management in former times. The arrival of new tools such as table-top scanning electron microscopes, have led to an increased interest in the topic. Unfortunately, there have been cases where a lack of documentation regarding instrument settings and selection criteria has led to questionable conclusions being drawn. Optical and scanning electron microscopy are powerful techniques, but they must be used correctly and with proper knowledge of their limitations. Furthermore, ancient fibre material is often difficult to examine due to issues such as sample degradation, mineralization and the scarcity of material, which means that conclusions based on a statistical analysis of a large number of fibres are essentially not possible. In a cultural heritage context, it is therefore essential to distinguish between characteristic features, by which we mean features that are often, but not always present in a particular species and distinguishing features, which are always present in a particular species and can therefore be used for identification even if only a small amount of sample material can be examined. We argue that the community will have to accept that, quite often, a secure identification is not possible and that absolute statements such as: "This textile is made of flax" will often have to be replaced by relative statements such as "The material is likely to be flax". In this paper, we address these issues as follows: first, we present a fibre identification diagram which can be used, with some limitations, to distinguish between flax, hemp, nettle, jute, hops, and cotton using optical and electron microscopy. We then move on to highlight some of the typical pitfalls of using optical and electron microscopy for fibre identification. Finally, we present measurement documentation tables for optical and electron microscopy images, which we suggest should always be included in publications. Material scarcity means that the amount of material used for investigations should be kept at an absolute minimum. It is thus crucial that results are published with proper documentation so that measurements do not need to be repeated (more material is used) in future studies. It is our hope that the measurement documentation tables will be adapted by the community and used in future publications in the field. The paper finishes with a demonstration example, presenting a fibre analysis of Viking Age textile fragments from the 10th Century with documentation tables. [ABSTRACT FROM AUTHOR]

This research aims to study the effect of injection parameters on the mechanical properties of the developed green composites. Natural flax fibre and biodegradable polymer, polylactic acid was chosen to develop the green composites. The flax fibre was chemically treated using sodium hydroxide to fabricate the green composite by injection moulding. The injection parameters namely (i) injection pressure (bar), (ii) injection speed (mm/s), and (iii) injection temperature (°C) was considered to investigate their effect on the mechanical properties of developed polylactic acid/flax green composites. The mechanical properties, such as (a) tensile strength (TS), (b) tensile modulus (TM), (c) percentage elongation under tensile loading (PET), (d) flexural strength (FS), (e) flexural modulus (FM), (f) percentage elongation under flexural loading (PEF), (g) compressive strength (CS), and (h) shear strength (SS) was evaluated under different injection conditions. Furthermore, the morphology of the mechanically tested specimens was investigated using a scanning electron microscope. Grey relational analysis was performed to find the optimal injection condition. The optimum injection condition depicting superior mechanical properties was found at injection parameters combination of 90 bar (injection pressure), 60 mm/s (injection speed), and 165 °C (injection temperature). [ABSTRACT FROM AUTHOR]

Due to the depletion of petro‐based sources and environmental consciousness, researchers are striving to replace synthetic fibers and resins in composites with bio‐sourced ones without compromising their properties. In this regard, the present study investigates the effect of partially replacing epoxy moieties with castor oil based bio‐resins on various properties of epoxy resin and its flax fiber reinforced composite system to achieve sustainable materials, thereby encouraging the bio‐based theme. Base‐catalyzed transesterification was used to synthesize epoxy methyl ricinoleate (EMR) as a low viscous reactive green monomer derived from epoxidized castor oil (ECO). The influence of both ECO and EMR bio‐resin on various mechanical, thermo‐mechanical properties, free mode vibration, and water absorption of epoxy and its composites were studied. The composition with 20% of ECO and EMR was optimized based on stiffness‐toughness balance. The inclusion of 20% EMR significantly escalated the tensile, impact, and fracture toughness properties of epoxy composites by 6.45%, 12.8%, and 14.2%, respectively. The strong fiber‐matrix interface was confirmed by increased pullout adhesion by 21% and 35.1% due to the addition of ECO and EMR, respectively. Dynamic mechanical analyzer revealed a 12% higher storage modulus for EMR modified composites than ECO counterparts. Scanning electron microscope morphology revealed superior interfacial adhesion between fiber and matrix in case of EMR modified bio‐composite, which resulted in a lower water diffusion coefficient than ECO modified bio‐composite. These results showed that the 20% EMR customized epoxy composite is dimensionally stable with improved mechanical properties and may act as a green alternative to petro‐sourced epoxy composites in automotive and semistructural applications. Highlights: Effects of castor oil based bio‐resins on epoxy composites are studied.Composites with significant bio‐content (~50 wt%) are developed.EMR modified epoxy composites exhibited improved mechanical properties.A strong fiber‐matrix interface was confirmed by increased pullout adhesion.Reduction in pot life of epoxy was observed on adding ECO and EMR. [ABSTRACT FROM AUTHOR]

Global warming has led to a change in climatic conditions. Since 2006, drought has contributed to a reduction of food production and other agriculture-based products in many countries. The accumulation of greenhouse gases in the atmosphere has caused some changes in the composition of fruits and vegetables, making them less nutritious. To analyse this situation, a study was conducted on the effect of drought on the quality of fibres provided by the main fibre crops in Europe, namely flax (Linum usitatissimum). The experiment consisted of growing flax under controlled comparative conditions with designed different irrigation levels, such as 25%, 35% and 45% field soil moisture. Three varieties of flax were grown in 2019, 2020 and 2021 in the greenhouses of the Institute of Natural Fibres and Medicinal Plants in Poland. Fibre parameters, such as linear density, length and strength, were evaluated according to relevant standards. In addition, scanning electron microscope images of the cross-section and longitudinal view of the fibres were analysed. The results of the study indicated that deficiency of water during the flax growing season resulted in lowering of fibre linear density and tenacity. [ABSTRACT FROM AUTHOR]

A persistent rise in the costs of construction materials has led to the need to address this problem in line with the Sustainable Development Goals. This research employed vegetal soft and rigid fibers in a screed mortar to produce a sustainable fabric–cement matrix. Four different vegetal-dried fibers (hemp, flax, miscanthus, and bamboo) with dosages of 0.4, 0.6, 0.8, 1.2, 2, and 4 kg/m3 were used. Laboratory investigations were slump test, bulk density, air occluded, shrinkage, and mechanical strength. Scanning Electron Microscope (SEM) assessments were performed and analyzed on the natural fibers and the screed formulation. The results highlight that fiber dosages significantly influence the above-mentioned properties. [ABSTRACT FROM AUTHOR]

Organic fiber biocomposites have figured prominently in various industries of commerce during the last 3 to 5 years owing to their remarkable physical and mechanical abilities. The main purpose of this experimental research is to evaluate the biomechanical and geomorphologic belongings of nanostructured substance under naturalistic situations. To accomplish such a cognitive approach, flaxseed strands are employed as reinforcing, nano-based graphene as an additive, and epoxy as a matrix phase, with the following restrictions in imagination: (i) fiber lengths, (ii) fiber volume fraction, and (iii) weight proportions of nanoparticles. The nanocomposites are combined by means of the hand lay-up process based on the Taguchi orthogonal specification. The material characteristics of the substance, like bending, tension, and shock characteristics, are assessed in line with the standard specification. The material properties of mixtures' second levels are the highest when compared to all other configurations. The elastic modulus of nanoparticle biocomposites revealed that 2% graphene provides 32.39 percent, 4% graphene provides 36.39 percent, and 6% nanoparticle pertains to 31.23 percent. Fractured images captured using scanning electron microscope of cracked samples have been used to comprehend the overall failure mechanism of a composite in mechanical characterization. [ABSTRACT FROM AUTHOR]

A mixed microbiologically composite made from natural Linum usitatissimum fibers with nano-reinforced organic plastics can improve properties while being environmentally friendly. The inclusion of aluminium tris hydroxide particles into an organic polymer enables it to maintain stiffness without sacrificing durability, even while improving barriers and material characteristics. A study of numerous composite samples verified this complementary effect, with combinations including 10 percent EMS and 2.6 wt.% ATH retaining the resin's stiffness, stress to breakage, and mechanical properties while improving durability. Mechanical tests such as tensile and impact strength were discovered using the conventional ASTM test plan. Best-practice designs which maximize constituent interactions are thus attainable, and the research findings serve as the basis for discovering this balance, thereby broadening the spectrum of microbiologically polymer nanocomposites. The cracked surfaces of the nanomaterials, and the amount of dispersion of an ATH filler, were examined using a scanning electron microscope. [ABSTRACT FROM AUTHOR]

Three Cd2+ resistant bacterium's minimal inhibition concentrations were assessed and their percentages of Cd2+ accumulation were determined by measurements using an atomic absorption spectrophotometer (AAS). The results revealed that two isolates Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52), identified by 16S rDNA gene sequencing, showed a higher percentage of Cd2+ accumulation i.e., 83.78% and 81.79%, respectively. Moreover, both novel strains can tolerate Cd2+ levels up to 2000 mg/L isolated from district Chakwal. Amplification of the czcD , nifH , and acdS genes was also performed. Batch bio-sorption studies revealed that at pH 7.0, 1 g/L of biomass, and an initial 150 mg/L Cd2+ concentration were the ideal bio-sorption conditions for Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52). The experimental data were fit to Langmuir isotherm measurements and Freundlich isotherm model R2 values of 0.999 for each of these strains. Bio sorption processes showed pseudo-second-order kinetics. The intra-diffusion model showed X i values for Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52) of 2.26 and 2.23, respectively. Different surface ligands, was investigated through Fourier-transformation infrared spectroscopy (FTIR). The scanning electron microscope SEM images revealed that after Cd2+ adsorption, the cells of both strains became thick, adherent, and deformed. Additionally, both enhanced Linum usitatissimum plant seed germination under varied concentrations of Cd2+ (0 mg/L, 250 mg/L,350 mg/L, and 500 mg/L). Current findings suggest that the selected strains can be used as a sustainable part of bioremediation techniques. [Display omitted] • Cd2+ tolerant Bacillus paramycoides and Bacillus tequilensis first isolated from coal mines near district Chakwal. • Langmuir and Frendlich models dominated adsorption of Cd2+ by both strains. • Q max value for B. paramycoides was 467.2 mg/g and for B. tequilensis was 444.05 mg/g. • czcD gene present in both bacteria. • Enhanced growth attributes observed in inoculated Linum usitatissimum L. [ABSTRACT FROM AUTHOR]

In this research work, the natural fiber reinforced hybrid epoxy composites were fabricated using the hand lay‐up method. The flax and kevlar are used as a reinforcement and epoxy as a binding material. This study aims to analyze the influence of stacking sequence and hybridization on the mechanical, water absorption, and morphological properties of polymer composites. The results reveal that the neat kevlar reinforced composite achieved a maximum tensile strength, modulus, and impact strength of 189.94 MPa, 2345.35 MPa and 37.16 kJ/m2 respectively with less water absorption behavior. Whereas, the hybrid composite with kevlar as an outer layers and flax as core layers was exhibited a maximum flexural strength, modulus, and inter laminar shear strength of 360.76, 37124.2, and 213.51 MPa, respectively. The water absorption percentage was more in neat natural flax reinforced epoxy composite due to its more hydrophilic nature. The scanning electron microscope analysis reveals the proper bonding and adhesion of both kevlar and flax fabrics with the epoxy matrix. [ABSTRACT FROM AUTHOR]

Material experts are striving to use natural resources as skin and core in composite sandwiches to achieve light weight, biodegradability, and cost benefits. This paper reports one such newly developed green composite sandwich and its biodegradable behavior. The skin and core of newly developed sandwich are flax fiber and agglomerated cork respectively. This composite sandwich is manufactured by vacuum bagging technique in order to get higher volume fraction of fiber. The biodegradability testing of the composite sandwich has been executed by soil burial test. The verification of the same has been done using Scanning Electron Microscope (SEM) images, Fourier Transform Infrared Spectroscopy (FTIR) analysis and Thermoanalytical test. The test results portray the percentage of weight loss in the specimens and that, it increases with burial time. It also depicts that the newly developed Green Composite Sandwich (GCS) has 82% higher degradation than the Synthetic Composite Sandwich (SCS) taken for the comparison. SEM images show that the green composite sandwiches have lost their fibrous structure and cell wall surface due to the degradation. FTIR and Thermoanalytical tests also confirm the biodegradability of the developed green composite sandwich. [ABSTRACT FROM AUTHOR]

The article is devoted to solving of actual questions linked with improving of the technological properties of flax fiber to expand the possibilities of its use in the composites industry. The multidirectional dependences of the influence of the polymer components content of scutched flax on the linear density, flexibility and specific strength of flax complexes was estimated. The multidirectional influence of different lignin structural formations to change the indicators with the optimum residual content of lignin is 3 wt% was demonstrated. A variant of enzymatic treatment for the development of the fiber pore structure was proposed. This variant provides the use of products forming after polysaccharide enzymatic destruction as reagents to destruct the large inter-fiber lignifications lowering the crushing uniformity of bast fiber bundles and the material strength properties impair. A 4-fold increase in the internal free volume and formation of nanoscale cavities on the fiber surface was demonstrated using the low-temperature adsorption of nitrogen and scanning electron microscope method. This is useful to improve the interfacial adhesion of the polymer binder. The transformation of lignin into a nanodisperse state was confirmed by the dynamic light scattering, Fourier-transform infrared and ultraviolet spectroscopy methods. As a result of the migration of depolymerized lignin into the structure of elementary fibers increases the strength of a linen fabric by 1.4–1.7 times and decreases its variation coefficient for breaking load by 2–2.7 times, and also improves its lightfastness and decreases the strength losses during insolation by 1.6–2 times. • A polymer composition of scutched flax fibre influence on the performance of the hackled flax fibre obtained from them. • Different lignin structural formations perform the multidirectional effects in the change of technological indicators. • Spatially localized destruction of interfiber lignifications generates reagents for lignin redox transformations. • Composition-property correlations use for describing influences polymeric composition to their fineness and deformation. • Low-modulus biomodification transform lignin to nanolignin that self-healing of internal defects in the elementary fiber. [ABSTRACT FROM AUTHOR]

Despite their scarce resistance to humid or wet conditions, natural fiber reinforced composites (NFRCs) seem to be able to partially recover their performances under discontinuous exposition to marine environment. To investigate this peculiarity, flax fiber reinforced composite was at first subjected to salt-fog spray condition at 35 °C for 15 and 30 days, respectively, and then stored in "dry" condition (i.e., 50% R.H. and 22 °C) between 0 and 21 days. The performances evolution was evaluated through flexural tests, water uptake and contact angle measurements. Moreover, the morphology of fractured mechanical samples was examined by using 3D optical microscope and scanning electron microscope (SEM). Flax fiber reinforced composite experienced phenomena of both reversible and irreversible degradation during the wet phase thus evidencing a relevant mechanical recovery thanks to the drying. Quite interestingly, the laminate showed an almost complete recovery of the flexural strength, meaning that this property is more strictly related to mainly reversible aging phenomena whereas the greater stiffness loss is more probably due to irreversible ones. • Natural Fiber Reinforced Composites were aged under alternated salt-fog and dry steps. • Flexural tests, water uptake and water contact angle measurements were performed. • NFRCs experienced reversible and irreversible degradative phenomena. • Due to the drying, NFRCs showed an almost complete recovery of flexural strength. • A topological map discriminating reversible and irreversible aging zones was created. [ABSTRACT FROM AUTHOR]

• The viscoelastic behavior of FFRP after water aging is studied. • The material properties of a wider range of frequencies is obtained through TTS. • The proposed model can be applied in viscoelastic analysis of natural FRPs. With the growing demand for sustainable and environmental-friendly materials, NFRP (Natural Fiber Reinforced Polymer) is increasingly used in the construction fields. FFRP (Flax Fiber Reinforced Polymer) is one of the major NFRP. Both storage modulus and damping factor of FFRP are related to frequency and temperature. Time-temperature equivalent principle is applied to obtain the material properties of a wider range of frequencies. A modified Huet-Sayegh viscoelastic model based on fractional derivative is used to predict the test data, and the fitting results show good agreement. After soaked in water, the storage modulus of FFRP is reduced and its loss factor is increased. SEM (Scanning Electron Microscope) analysis shows that water weakens the fiber/epoxy interface, therefore the dynamic properties of FFRP are influenced. [ABSTRACT FROM AUTHOR]

The study investigated the effectiveness of the combination of chemical and physical methods of natural fibers' modification. The long flax fibers were subjected to various types of modification. These were silanization, plasma modification and a combination of these methods. For the silanization process, two types of silanes were used: amino- and vinylsilane. The application of structurally different compounds allowed us to acquire knowledge about the effect of the modifier structure on its properties. Various properties of flax fibers were investigated, comparing the results before and after different modification processes. The flammability of prepared samples were tested by pyrolysis combustion flow calorimeter (PCFC). In the effect of the natural fibers' modifications, flammability was reduced even by 30%. The thermal stability of modified fibers increased. The FTIR tests of the gases released during thermal degradation of the tested fibers allowed us to determine the important compounds and prove a lower degree of flax-fiber decomposition after modification. Flax fibers were also tested to evaluate their physical properties (linear mass, average diameter, aspect ratio and hygroscopicity). Changes in surface morphology were observed by scanning electron microscope (SEM). The properties of natural fibers improved significantly, thus contributing to an increase in their suitability for the use in composites. [ABSTRACT FROM AUTHOR]