Durability Of Fibers Research Articles

Initial material for breeding of fiber flax under conditions of the Volga-Vyatka region

Sixty two cultivar samples of fiber flax of various ecological-and-geographic origin were studied for basic economically valuable traits (straw and seed productivity, fiber content and its quality) in 2014–2016 under conditions of the Volga-Vyatka region (Kirov oblast). The best genotypes were identified in terms of a set of traits: Flax of Heilonjiang no. 7 and no. 10; Heiya 11, 13 and 14; Huanguang 2 (China); Belinka (the Netherlands); and AP5 (Russia). Straw yield depends on the stem technical length (r = 0.71–0.76). Cultivar samples having high fiber contents (28.7–34.5%) are identified: Mirazh, Tverskoi, AP5, AP6, Pskovskii-93, Dobrynya, Nord, Peresvet (Russia), B-179 (Lithuania), and Merilin (the Netherlands). High fiber durability is characteristic of samples Soglasie (Belarus)—20.3 kgf; Er-27 (Russia)—18.5 kgf; and B-179 (Lithuania)— 17.8 kgf.

Effects of Diameter on the Durability of Glass Fiber–Reinforced Polymer Bars Conditioned in Alkaline Solution

AbstractCurrent standards do not consider the diameter of glass fiber-reinforced polymer (GFRP) bars used as internal reinforcement in concrete structures to be a factor influencing bar durability....

Fatigue fracture of fiber reinforced polymer honeycomb composite sandwich structures for gas turbine engines

Fiber reinforced polymer honeycomb composite sandwich structures are commonly used in different industries. In particular, they are used in the manufacture of gas turbine engines. However, fiber reinforced polymer honeycomb composite sandwich structures often have a manufacturing flaw. In theory, such flaws due to their rapid propagation reduce the durability of fiber reinforced polymer honeycomb composite sandwich structures. In this paper, bending fatigue tests of fiber reinforced polymer honeycomb composite sandwich structures with manufacturing flaws were conducted. Comparative analysis of fatigue fracture of fiber reinforced polymer honeycomb composite sandwich specimens was conducted before and after their bending fatigue tests. The analysis was based on the internal damage X-ray observation of fiber reinforced polymer honeycomb composite sandwich specimens.

Investigation of Structure and Property of Indian Cocos nucifera L. Fibre

Structure and physico-mechanical properties of Cocos nucifera L. fibre from a specific agro-climatic region of India, was thoroughly studied. Fine structure of the fibre was examined by Fourier Transform Infra-Red (FTIR) spectroscopy, Thermo-Gravimetric Analysis (TGA), X-Ray Diffraction (XRD), component analysis, Scanning Electron Microscope (SEM) and optical microscope. SEM shows prominent longitudinal cracks and micro-pores on the surface. XRD shows a low degree of crystallinity (45%), bigger crystallite size, and even the presence of appreciable amount of non-cellulose matter. FTIR reveals presence of large quantities of hydroxyl, phenolic and aldehyde groups. Component and thermal analyses indicates presence of cellulose and lignin as major components. Physical parameters reveal that, fibres are highly variable in length (range 44–305 mm), and diameter (range 100–795 µm). Mechanical properties of the fibre viz. breaking tenacity, breaking extensibility, specific work of rupture, and coefficient of friction were measured. Microbial decomposition test under soil reveals excellent durability of coconut fibre which makes it appropriate for the application in geotextiles. Mass specific electrical resistance of 4 Ω-kg/m2 indicates its enhanced insulation as compared to the jute.

Study of the degradation of non-conventional MgO-SiO2 cement reinforced with lignocellulosic fibers

This paper assesses the use of low alkaline composites based on magnesium oxide and silica (MgO-SiO2) cement and reinforced with cellulose fibers for the production of thin elements to resist bending loads. The strategy adopted was to study the durability of lignocellulosic fibers in a lower pH environment than the ordinary Portland cement (OPC), by comparing the flexural performance of samples at 28 days and after 200 accelerated ageing cycles. Two types of vegetable fibers were used: eucalyptus and pine pulps. For both types of fibers, composites made out of MgO-SiO2 cement after ageing treatment show a better mechanical performance than OPC samples (modulus of rupture of ∼10.5 and 9 MPa respectively). When used in MgO-SiO2 cement matrices, eucalyptus fibers offer excellent specific energy (SE) values (∼5 kJ/m2) compared to OPC samples in which SE drastically decreases after ageing from 4.97 kJ/m2 to 0.14 kJ/m2. The preservation of the reinforcing capacity of the composite materials after ageing was also proved by SEM techniques. In the light of the results, the use of MgO-SiO2 cements is an effective way to apply cellulosic fibers as reinforcement in fiber-cement products since no signs of degradation were found, even improving flexural properties over time.

222 - Comparison of Holmium laser fibers: Evaluation of fiber durability and flexibility

222 - Comparison of Holmium laser fibers: Evaluation of fiber durability and flexibility

Flexural Performance Evaluation of Hybrid Concrete Filled Fiber Reinforced Polymer Plastic (FRP) Tube Connection

In the construction industries, in order to compensate material disadvantages of existing construction material (concrete, steel, wood, etc.) and satisfy requirements of the structural performance, research on durable and outstanding corrosion resistant fiber reinforced polymeric plastic (FRP) is actively underway. In general, a pile cannot be produced with unlimited lengths because of the size of the manufacturing machine and transportation to construction site. Therefore, the connection of pile and structural integrity of connection should be considered in the pile design. In this paper, hybrid FRP-concrete composite pile (HCFFT) was investigated by focusing on the connection of HCFFT members. The connection capacity of HCFFT was evaluated by the experiment and the finite element analysis. From the results appropriate connection method of HCFFT is discussed.

Salt-fog spray aging of jute-basalt reinforced hybrid structures: Flexural and low velocity impact response

Abstract In this work, a study on the aging resistance of jute and jute-basalt interply hybrid laminates exposed to salt-fog is presented with the aim to investigate the possibility to enhance the durability of natural fiber reinforced composites for marine application by a ply-substitution approach. In particular, jute and basalt/jute reinforced composite plates were manufactured by vacuum assisted resin infusion in two different staking sequences (i.e., intercalated and sandwich-like basalt-jute) and aged under salt fog conditions. The effects of the accelerated aging at increasing times on the mechanical response of laminates were assessed in both quasi static (three point bending) and dynamic (low velocity impact) conditions. Overall, it was found that the substitution of external jute layers with basalt layers (i.e. sandwich like configuration) represents the best solution to enhance the durability of structures exposed to salt fog aging conditions. This is highlighted by lower decrements, after 90 days of aging, of the quasi-static flexural modulus and the impact peak load (16% and 3.5%, respectively) compared to those showed by jute laminate (40% and 10.5%, respectively).

Effects of UV irradiation and condensation on poly(ether-ether-ketone)/carbon fiber composites from nano- to macro-scale

Durability and damage mechanism of carbon fiber–reinforced poly(ether-ether-ketone) composites (T300/PEEK) have been investigated under ultraviolet (UV) and water condensation conditions for 1560 h. The tensile modulus decreased by 5.4% after 1560 h of exposure, while no significant changes were found in tensile strength. The microhardness and elastic modulus of the resin measured by atomic force microscope–based nanoindentation were found to be dramatically increased after 240 h treatment and then decreased after longer treatment. The thermal decomposition temperature decreased from 549° to 522° after 840 h of exposure due to the formation of side chains and low molecular products induced by UV. The damage of resin was attributed to chain scission and recombined cross-linking by UV irradiation and hydrolytic deterioration by hydrothermal conditioning, where the decomposition led to the formation of carbonyl groups and hydroxyl groups, as well as the reduction of ether groups determined by Fourier transform infrared spectroscope. Scanning electron microscopy analysis on tensile fractures near the exposed surface indicated fiber/matrix debonding. The resin on the surface degraded rapidly, and its roughness increased continuously from 30.8 ± 4.1 nm to 88.8 ± 6.8 nm after 840 h of degradation, with the formation of microholes and microcracks. A degradation mechanism was proposed, and the accelerated weather aging affected only the surface region of T300/PEEK.

Effect of Mineral Admixture (Alccofine-1203) on Durability of Hybrid Fiber Reinforced Concrete

Objective: To estimate effect of mineral admixture (Alccofine-1203) on durability of Hybrid Fiber Reinforced Concrete. Methods/Analysis: This paper presents effect of hybrid fibers and alccofine-1203 on estimation of durability of hybrid fiber reinforced concrete with different combinations. The final combination is used as fiber volume fraction - 1.5% (80% steel fibers and 20% polypropylene fibers) by volume of concrete and Alcoffine-1203 with 7.5% by weight of cement. Findings: The study presents behavior of hybrid fiber (steel fibers and polypropylene fibers) reinforced concrete including mineral admixture like Alccofine-1203. The hybrid fibers help to reduce the cracks due to shrinkage, creep and early age thermal cracking along with increase in ductility, toughness and fatigue resistance. The mineral admixture (Alccofine-1203) enhances strength of concrete, modulus of elasticity along with workability, durability and reduction in segregation. Novelty/Improvement: Addition of Hybrid fibers and mineral admixture (Alccofine-1203) increases the ductility, crack resistance strength and durability of concrete.

Combined Effects of Sustained Loads and Wet-Dry Cycles on Durability of Glass Fiber Reinforced Polymer Composites

This paper deals with durability of glass fiber reinforced polymer (GFRP) composites under the combined effects of sustained tensile loads and wet-dry (WD) cycles. Two different solutions (distilled water and saltwater) were used to imitate the freshwater and marine environments, respectively. Tensile properties of the unconditioned and conditioned specimens were measured to study the durability of GFRP composites under these 2 effects. The response indicated that both tensile strength and elastic modulus increased initially upon WD cycles, which was attributed to both the postcuring of resin and the sustained tensile stress allowing for fastec cure. Further exposure to WD cycles in distilled water or saltwater led to a steady decrease in tensile strength and modulus. WD cycles of saltwater and distilled water have similar effects on the degradation of the tensile properties for unstressed specimens. However, the elastic modulus and elongation at rupture of stressed specimens under WD cycles of saltwater decreased more than those specimens under WD cycles of distilled water. Moreover, increase of sustained loads led to a decrease in tensile strength. Based on Arrhenius method, a prediction model which accounted for the effects of postcure processes was developed. The predicted results of tensile strength and elastic modulus agree well with those obtained from the experiments.

Experimental study of the effect of adding fan palm fibers on concrete durability exposed to severe environments

Adding Fiber to Concrete became a common practice to improve its durability, but for environmental purposes, it is preferable to use natural fibers instead of synthetic ones. In addition, using fibers prepared from tree waste that improves many concrete physical and mechanical properties is environmentally effective and costly preferable. Natural fibers extracted from Fan Palm trees that were cured chemically when used in concrete lead to improvements in concrete physical and mechanical properties. On the other hand, one of the major challenges that faces the commercial use of natural fibers in concrete is its durability. For that reason, an experimental program was conducted to study the durability of natural fibers by measuring the volume stability of the concrete when exposed to different severe environment conditions. The investigation recorded the length change of concrete bars with 1% fiber volume fraction and without fibers when exposed to sea water, solution with 2% MgSO4, 2% Na2SO4, and NaOH for a period of 150 days. The study was performed on three grades of concrete 30MPa ,40MPa, and 60MPa to monitor the effect of different concrete grades on the results. From the results, it can be concluded that adding Fan Palm fibers to concrete significantly improves its resistance when exposed to sea water, MgSO4, Na2SO4, and NaOH solutions. After 150 days of exposure to harsh environment, the expansion of concrete bars for length change measurements was recorded for the concrete with fibers and compared to that of control mixture (without fibers). The reduction was between 20% and 40% for different Concrete grades and solutions. In Summary, Fan Palm Fibers maintain their durability in concrete when exposed to severe chemical exposures. In addition, adding natural fibers to concrete decreases concrete bar Expansion thus improves its durability.

Facile synthesis of an eco-friendly nitrogen–phosphorus ammonium salt to enhance the durability and flame retardancy of cotton

An eco-friendly AEGDP flame retardant reacted with –OH groups from cotton to enhance the durability and flame retardancy of cotton fibers.

Short-Term Durability of Hemp Fibers

Short-term durability tests on hemp-fiber confined concrete cylinders made up of one layer of hemp-fiber bundles were conducted to study their behavior. Compression test was performed after wetting and drying cycles in both water and seawater. Moreover, uniaxial tension test on hemp-fiber bundles was conducted to study the effect of extended W/D cycles and prolonged exposure to moisture (1,800 hours). Hemp-fiber confined concrete cylinders showed promising results where there was no significant change in both compressive strength and ductility in comparison to control wrapped cylinders. Regarding tensile testing, after prolonged exposure to water, hemp-fiber bundles were completely destroyed. On the other hand, epoxy coating provided a suitable protected configuration to hemp-fiber bundles. Resistance to seawater was highly apparent in the conservation of tensile stresses. Therefore, natural fibers could be recommended as an alternative to synthetic fibers while taking their drawbacks into account.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ЩЕЛОЧНОЙ ОБРАБОТКИ НА СОСТАВ И СВОЙСТВА ЭЛЕМЕНТАРИЗОВАННОГО ЛЬНЯНОГО ВОЛОКНА

The possibility of modification of linen fibers according to the essentially new technological scheme which includes purposeful destruction of connective tissues by the action of cyclic de-forming loads (elementarization) with the subsequent chemical processing is proved. The analysis of properties of the obtained elementary fibers of natural origin has shown that geometrical indicators of flax elementary fibers are close to the ones of cotton and wool fibers, and their du-rability is considerably higher, that gives the prospects to create innovative products for technical, textile and medical purposes on their basis. The influence of chemical processings, modeling the processes of modification and upgrading of flax materials, on the composition of basic admixtures and properties of elementarized fibers is investigated. It is shown that the high extent of purification of elementarized fibers raises the possibility of cellulose destruction. The selection of chemical reagents and concentration and time parameters of the process, which provide the optimum extent of purification of elementarized fibers without the destruction of its cellulose component, is carried out. It is determined that chemical processings of elementarized flax fibers in comparison with the cottonized ones have to be carried out in softer conditions: the concen-tration of alkali – to 2 g/l, the processing duration – up to 60 min. As the alkaline reagent the bases weaker than sodium hydroxide can be applied, in particular, sodium carbonate. The insig-nificant destruction of cellulose noted during the subsequent influence of an oxidizer is confirmed by small contents of carboxyl and aldehyde groups in it and also by the durability indexes of new type of fibers: the durability of fibers before and after the chemical processings has no significant differences and is within the limits 40,4–42,0 sn/tex.

Experimental study on bond durability of glass fiber reinforced polymer bars in concrete exposed to harsh environmental agents: Freeze-thaw cycles and alkaline-saline solution

Abstract This study presents an experimental investigation on the bond durability of GFRP bars in concrete when subjected to harsh environments. The pullout specimens having different concrete covers were designed based on a created database to demonstrate the generality of the current experimental program. The freeze-thaw (FT) cycles, alkaline-saline (AS) solution, and both coupled effects were used to simulate environmental conditions in cold regions. The durability performance in terms of the failure mode, weight loss, relative dynamic modulus of elasticity, durability factor, as well as the bond strength, were measured and investigated accordingly. The test results revealed that the concrete cover with three times of the bar diameter was not sufficient to resist the environmental agents when exposed to weathering, including FT cycles, in which all the pullout specimens failed by concrete splitting. The coupled scenario of FT cycles and AS solution was observed to be the worst case among all the environmental conditions. Moreover, the analytical models: modified Bertero-Eligehausen-Popov (mBPE) model and Cosenza-Manfredi-Realfonzo (CMR) model, were calibrated by considering the environmental influences based on the experimental data to better demonstrate the degradation of GFRP-concrete bond.

Effect of Hygrothermal Loading on Laminate Composites

Objective: To find the effect of hygrothermal loading on CFRP and GFRP composite materials by finding the properties like capacitance, micro hardness, moisture diffusivity and area of fraction. Methods: Hand layup and vacuum bag methods were used for fabrication of composites. Finding: Three-point bending test was done on each specimen by varying load, i. e, zero load, with 30% load, 50% load and 70% load for different time periods. Micro hardness and capacitance were determined using Vickers Hardness tester and LCR meter respectively on both the composites before and after the thermal treatment. The capacitance increased with time whereas the percentage area of fraction of the fibre decreased. Also, the reduction in strength and damage to fibre were investigated using SEM. It was observed that with increase in %weight gain, micro hardness of specimen decreased. Application/Improvement: FRPs can substitute traditional steel reinforcements in reinforced concrete structures. The continuous loading under thermal actions due to natural environmental factors lead to degrading effect that needs to accurate investigations in evaluating durability of fibre reinforced polymers.

Concrete Bond Durability of CFRP Sheets with Bioresins Derived from Renewable Resources

AbstractBond strength durability of carbon fiber–reinforced polymer (CFRP) to concrete is investigated for two bio-based resins and compared with conventional epoxy (E). The first is an epoxidized pine oil blend (EP) and was used for wet layup installation. The second is a furfuryl alcohol resin derived from corn cobs and sugar cane (FA), and was used to prefabricate CFRP plates, which were installed using an epoxy paste. A total of 137 concrete prisms with a midspan half-depth saw cut were tested. Specimens were conditioned in a 3.5% saline solution at 23, 40, or 50°C for up to 240 days before testing for bond strength. Short-term bond strengths were 3.9, 4.3, and 5.5 MPa for the E, EP, and FA resins, respectively, using a 33 MPa concrete. Reductions in bond strength over the 240 days of conditioning did not exceed 15%. Bond failures of E-CFRP (EC) and EP-CFRP (EPC) were predominantly adhesive-based, where a thin layer of cement paste remained attached to CFRP, while that of FA-CFRP (FAC) was cohesive-ba...

Investigation of the durability and stability of piezoelectric textile fibres

Polymers such as polyvinylidene difluoride, polypropylene and polyamide-11 show great promise for providing light-weight, flexible and fibrous piezoelectric materials that can be integrated into technical textile fabric structures for energy harvesting applications. Durability is an important parameter for the textiles and especially for functional and smart materials. This research work provides an insight on the piezoelectric behaviour of polypropylene, polyamide-11 and polyvinylidene difluoride in terms of peak-to-peak voltage generation capabilities after washing at 40°C with the addition of detergent as described in test method BS EN ISO 105-C06:2010. It was observed that the peak-to-peak voltage generated by polypropylene monofilaments retained similar values with only slight differences, while the monofilaments of polyvinylidene difluoride and polyamide-11 showed higher peak-to-peak voltage generation after washing. These changes have been explained using the changes in the crystallinity and phase, as determined by Fourier transform infrared spectroscopy analysis.

Durability of CFRP strengthened circular hollow steel members under cold weather: Experimental and numerical investigation

The durability of carbon fibre reinforced polymer (CFRP) strengthened steel circular hollow section (CHS) member under prolonged cold weather has not been explored sufficiently. Furthermore, various parameters that may affect the durability of such members have not been revealed yet. This paper presents an analytical and experimental study with a finite element (FE) approach to study the effects of prolonged cold weather (+3°C) exposure on CFRP strengthened CHS member subjected bending. It was found that a prolonged exposure about 12month cold weather immersion adversely affected the durability of strengthened beams by reducing strength and stiffness. Durability design factor has been recommended. The proposed analytical models and FE models were found in good agreement with the experimental results. The results of parametric studies showed that the durability design factors varied from section to section, CFRP with higher tensile modulus and higher number of CFRP layers performed better in cold weather.