Effect Of Moisture Absorption Research Articles

Effects of absorption on the tribological properties of carbon fiber reinforced PA 6 composites manufactured by fused deposition modeling

Abstract The present work studied the water absorption behavior of polymeric composite materials fabricated using 3D printing technology, as well as its effect on their tribological properties. The results showed that the moisture absorption would impair the mechanical properties of polymer matrix and interface bonding between fiber and matrix. As a result, the tensile strength of the fiber reinforced polymer composites (FRPCs) decreases with water absorption. Nevertheless, the effects of moisture absorption on the wear properties of FRPCs are more complicated, which are depending on the fiber length and sliding conditions. With the short fiber reinforcements, moisture absorption deteriorated the wear resistance under all the testing conditions. With the increase of moisture level, more severe fiber damage/removal was observed, associated with the higher wear loss. With a relative high volume fracture of continuous carbon fiber (∼ 35 vol.%), however, the wear resistance of the FRPC increased with moisture level, especially under a relatively low load. Based on microscopic observations, it was proposed that water inside FRPC specimens is able to provide the lubricating and cleaning effects, which contribute to a lower friction and smooth worn surfaces. The work provides new insights into designing and selecting printed polymer materials, subjected to different loading conditions.

An overview of the effects of water and moisture absorption on the performance of hemp fiber and its composites

AbstractResearchers compare natural hemp fibers with synthetic fibers because of their distinct physical and mechanical properties, which have been well established over time. Hemp fibers are a versatile type of plant fiber commonly used in structural composites and have shown promise in various applications which include packaging, construction, and automotive parts. However, designing hemp‐based composite components presents challenges due to factors related to the plant's origin, growth conditions, age, stem position, separation methods, and the irregularity of fiber cross‐sections. This review aims to provide a comprehensive analysis of research on the performance of hemp fibers and their composites concerning moisture and water absorption. It reviews and analyzes important research on the water and moisture absorption properties of hemp fibers. The article also explains the critical properties of hemp fibers, the various factors affecting these properties, the role of hemp fibers in reinforcement composites, and how relative humidity and swelling characteristics impact hemp fiber composite components. Additionally, it highlights potential areas for future research.Highlights Effects of moisture on hemp fiber's structural properties. Mechanisms of water and moisture absorption in hemp fibers. Impact of moisture on hemp fiber reinforced composites. Key factors in selecting matrices for hemp fiber composites. Future prospects for hemp fiber composites in various applications.

Effect of moisture content in polyether-ether-ketone (PEEK) filament on 3D printed parts

Polyether-ether-ketone (PEEK) is a recently commonly used high-performance thermoplastic material with high heat resistance, high chemical resistance, high water resistance, and high wear resistance. Polyether-ether-ketone products with complex structures manufactured through the 3D printing process of fused filament fabrication (FFF) are emerging in the medical field. However, similar to other plastics, PEEK materials are also hygroscopic. This may have an impact on 3D printed products. The effect of storage time of filament on 3D printed PEEK products under specific temperature and humidity conditions has not been further explored. This study is mainly to explore the moisture absorption of PEEK filament for different storage time and the effect of moisture absorption on the performance of 3D printed PEEK products. The correlation between storage time and moisture absorption is verified by experiment. It is found that moisture will affect the surface quality of PEEK products. In addition, the mechanical test results show that the increase in the amount of water absorbed leads to the decrease of material properties, such as tensile strength, density, and hardness. Therefore, it is recommended to store unused or leftover PEEK filaments under vacuum drying conditions. For PEEK filaments that are being printed, it should be ensured to replace them every less than 24 h.

Effect of moisture on the sensing capabilities of piezoelectric actuator/sensor pairs on flax fibre reinforced composite laminates

The sensitivity of the piezoelectric actuators’ response to the moisture uptake has been investigated on flax fibre reinforced composite laminates. Non-woven flax fabric was impregnated with epoxy and composite laminates were fabricated using hand lay-up and cured in a compression moulding machine. The laminates were initially impacted with a drop-weight impact machine at a low energy level, with the aim to generate an artificial surface crack that will allow the moisture to enter the fibre-matrix interface more effectively. A set of piezoelectric actuators and sensors were adhered on the surfaces of the composite panels in a specific rectangular arrangement to allow for wave capturing at various directions. The wave characteristics of the samples were extracted in pristine stage and then the samples were impacted and immersed in distilled water until saturation. At regular intervals after the water immersion, the panels’ weight was measured using a laboratory scale and the wave propagation characteristics of the materials ware measured in order to investigate the gradual effect of moisture on the capabilities of the actuators and sensors. The propagation of stress waves in the dry and wet samples was investigated and the effect of moisture absorption was examined experimentally using piezoelectric wafers until the saturation was reached. Finally, a continuum damage mechanics layerwise time domain spectral finite element model, both for the composite laminate and the rich resin layers, was also developed to simulate the materials’ performance under impact and evaluate the wave propagation within the material at the dry state.

Effects of moisture absorption on penetration performance of FRP sandwich structures

Fiber-reinforced plastic sandwich structures (FRPSSs) are increasingly used in marine applications thanks to their high levels of stiffness, lightweight, buoyancy and damage resistance to penetration and impacts. This paper investigates the effect of exposure to seawater conditions on mechanical behavior of FRPSSs with various core configurations loaded with indenters with different geometries. A new in-situ acoustic emission (AE) methodology is applied to monitor the moisture evolution process, while X-ray micro-computed tomography validated its influence on out-of-plane failure modes observed in quasi-static indentation experiments. Results indicate that AE velocity can effectively monitor the moisture uptake, serving as an in situ structural health monitoring approach. It was also revealed that the core configuration had a limited effect on moisture ingress. Samples exposed to sharp indentation exhibited the greatest decrease in load-bearing capacity (in excess of 50% in some cases) while that for blunt indentation was the lowest. This can be explained by reduced penetration forces resulting from matrix plasticization and degraded matrix/fiber interface, exacerbated by a smaller contact area. Also, early damage initiation and intensified damage progression were observed for sharp indenters after the seawater exposure. The core of FRPSSs significantly influenced localized damage in samples indented with conical and flat indenters, unlike those subjected to hemispherical ones. The seawater exposure adversely affected the energy absorption and penetration performance, enhancing macroscale damage mechanisms. These findings offer valuable insights for design and optimization of FRPSSs for marine applications.

Composite porous 3D foam for solar-driven atmospheric water harvesting in low humidity natural environment

Solar-driven atmospheric water harvesting (SAWH) has been recognized as a promising strategy to alleviate the freshwater crisis. Herein, we developed an efficient porous polymeric foam, LiCl@CCP-PPy, which has low preparation cost, strong adaptability and portability, and is very suitable for use as a wicking material in SAWH systems. LiCl@CCP-PPy contains abundant –NH2 and –OH groups. These hydrophilic groups and excellent pore structure (porosity is 80.22 %) make it have a good moisture absorption effect even in low humidity environment. The moisture absorption capacity can reach 2.86 g/g at 35 % RH and 25 °C, and 4.48 g/g at 25 °C and 90 % RH. The saturated water absorption effect was 27.48 g/g. LiCl@CCP-PPy can be scaled up for production. In addition, LiCl@CCP-PPy has a high light absorption rate of more than 90 %, and the strong photothermal conversion ability of Polypyrene (PPy) enables the material to warm up rapidly under natural light, thereby accelerating the desorption process (96 % desorption rate at 1 kW/m2 for 3 h). Based on the above properties, LiCl@CCP-PPy was applied to the Tengger desert in northwest China. The final water production efficiency was 0.64 L/m2/d, and the collected water quality met the international drinking water standard.

Effect of Alstonia Angustiloba tree moisture absorption on the stabilization of unsaturated residual soil slope

Effect of Alstonia Angustiloba tree moisture absorption on the stabilization of unsaturated residual soil slope

Analysis of water absorption on the efficiency of bonded composite repair of aluminum alloy panels

Abstract Carbon fiber-reinforced polymer (CFRP) exhibits aging effects over time that can degrade its mechanical properties. In this study, a systematic investigation was carried out to investigate the effect of distilled water aging on the mechanical properties of CFRP composite patch bonded on Al 2024-T3 plates. We built a finite element model to analyze the effect of water absorption by the composite and the adhesive on the effectiveness of the composite patch repair. Using the experimentally evaluated mechanical properties of CFRP and Araldite adhesive subjected to distilled water immersion, finite element simulations were validated. The experimental observations deduce that there was a negligible effect of moisture absorption on the bulk mechanical properties of CFRP and adhesive over time. However, a significant effect of moisture absorption was observed on the elasto-plastic behavior of both CFRP and adhesive. Consequently, the numerical simulations suggest that the moisture absorption reduces the bonded composite patch repair efficiency attributed to an increase in the plasticity around the crack front and accordingly increases the damage in the adhesive layer. This study attempts to provide guidelines on the severity of damage caused by water absorption on the performance of structures repaired with composite patches.

Effect of humid environment on electromechanical performance of piezoelectric micromachined ultrasonic transducers (PMUTs)

In recent years, piezoelectric micromechanical ultrasonic transducers (PMUTs) have received widespread attention. The deployment of PMUTs in humid environment exposes them to changes in relative humidity, which effects their electromechanical performance. This paper investigates the effect of humid environments (30 %−80 %) on the electromechanical performance of uncoated PMUTs from the perspective of electromechanical conversion model and equivalent circuit. Two types of transducers with different top layer materials were experimented to compare the effects of moisture absorption on the electromechanical performances of the transducers. The top layer material of Device A is SiO2 film, and the top layer material of Device B is Si3N4 film. The experimental results show that with the rise of relative humidity, the frequency of Device A decreases by −0.47 %, while the frequency of Device B increases by 0.13 %, and the phase resonance peaks of both increases by 0.441° and 0.285°, respectively. Equivalent circuit fitting was conducted on the impedance characteristics of Device A and Device B, and the fitting results were discussed based on acoustic impedance and moisture absorption theory. The electromechanical performances of the two devices show a different variation trend, with the potential reason being that Device A is mainly affected by the combined effects of moisture absorption leading to a decrease in Young’s modulus of the membrane and a decrease in the acoustic impedance of the humid air, while Device B is mainly affected by the acoustic impedance.

A high-throughput technique to evaluate the probability distribution of strength of adhesively bonded joints after moisture absorption

ABSTRACT The reliability of adhesive bond strength influences the applicability of structural adhesives in industries. The statistical probability distribution of the strength of adhesive joints is an essential indicator when designing and choosing adhesives. In this study, we experimentally studied the probability distribution of the strength of adhesive joints. The strength data were collected using a novel high-throughput technique consisting of a sample preparation method and shear testing device. Numerous cylindrical butt shear-joint specimens were prepared by mechanical machining and tested using a self-developed shear testing device. The effect of moisture absorption by the adhesive was specifically considered. The probability distribution of the shear strength of the epoxy adhesive joints was characterized using five probability distribution functions: Normal, Lognormal, Exponential, Weibull, and Gamma. Quantile – quantile plots were employed to determine the suitability of each distribution function. The results suggested that the Weibull and Normal distributions were best suited for describing the probability distribution of the strength of the epoxy adhesive joints. The Weibull distribution is particularly suitable for brittle epoxy adhesives. Moisture absorption reduced both the mean and variance of the shear strength, which might be attributed to the plasticization of the adhesives. The high-throughput method proposed in this study significantly improved the efficiency of testing adhesive joints. It not only contributes to the study of the strength distributions of adhesive joints but also helps to shorten the research and development cycle of new adhesives by facilitating rapid strength evaluation.

Effect of moisture absorption on the flexural strength of phenolic matrix composites reinforced with glass fibers and aluminum oxide nanoparticles

AbstractIn this research, the effect of adding aluminum oxide nanoparticles on the flexural strength of glass/phenolic composites that were exposed to water environment was experimentally investigated. To make glass/phenolic composites, IL‐800 phenolic resin, H002 hardener, T400 bidirectional glass fibers and Al2O3 nanoparticles were used. Four‐layer composite plates were made by hand layup method. Beam‐shaped samples were extracted from the plates with the help of laser cutting method. Rectangular composite beams made of glass/phenolic and Al2O3/glass/phenolic were subjected to three‐point flexural test. The moisture absorption test was continued until the amount of water absorption reached a constant level. Bending test was performed on the samples before and after immersion in water. Based on the results, the average flexural strength of the samples after water absorption shows a decrease of about 15%. This parameter is equal to 118.96 MPa for glass/phenolic composite samples immersed in water, and by adding 0.25 wt% of Al2O3 nanoparticles into the matrix material of glass/phenolic composite samples, the flexural strength reaches 142.54 MPa, which shows an increase of 19.82% compared to samples without nanoparticles. Furthermore, the amount of flexural modulus decreases after water absorption, and the addition of nanoparticles in the base material can compensate this reduction. Scanning electron microscopy images illustrate that the addition of Al2O3 nanoparticles into the phenolic resin can enhance the strength of matrix material and improve the adhesion of glass fibers to the resin.Highlights Addition of nano Al2O3 reduces water absorption of glass/phenolic composites. Nano Al2O3 improves composite flexural strength after water absorption. Addition of nano Al2O3 increases the adhesion between the layers of the specimens.

Effect of moisture absorption on curing of wind blades during repair

Effect of moisture absorption on curing of wind blades during repair

A COMPREHENSIVE ANALYSIS OF THE SPATIO-TEMPORAL VARIATION OF SATELLITE-BASED AEROSOL OPTICAL DEPTH IN MARMARA REGION OF TURKIYE DURING 2000–2021

Abstract. This study investigates the spatiotemporal variability of the aerosol optical depth (AOD) in the atmosphere over the Marmara region, Turkiye. Long-term satellite observations from MODIS MAIAC AOD data spanning the period from 2000 to 2021 are utilized. Examining the temporal variations in AOD in the Marmara region, it is observed that AOD reaches its peak during spring (May) and summer (August) months, while lower AOD values are observed in winter. Specifically, between August and December, there is a significant decline in monthly mean AOD which is majorly due to particulate removal from the atmosphere via precipitation scavenging. The findings reveal that the inter-annual variability of monthly AOD variations in the Marmara region is primarily influenced by temporary Saharan dust transportation with highest deviations from 22 year averaged AOD in late winters and early springs. The findings from the analysis of seasonal spatial variation of high AOD values revealed that the high AOD area is largest in the summer with about 54% of the total area and then spring (45%) and autumn (26%). Winter has the lowest HVA with 17% of the total area. The seasonal percentage rates of HVA are due to atmospheric conditions and aerosol sources. Larger HVA in summer is due to the increase of farming practices and biomass residue burnings combined with high moisture absorption effects and high temperature. The heating-specific emissions are the main source of anthropogenic emissions over the high AOD areas during the autumn and winter and aerosols are concentrated over the urbanized centres and industrialized zones.

Moisture Absorption, Desorption and Reabsorption Effects on Mechanical Properties of Glass-Epoxy Composites

The glass-epoxy composite laminates were fabricated using BID glass fabric and RT cure epoxy matrix by Room Temperature Vacuum Bag Moulding (RTVBM) Technique. The Inter laminar shear strength (ILSS), compression and flexural strength values were determined at room temperature for their dry mechanical property evaluation. The test specimens were exposed to a temperature/humidity condition at 45° C/95% RH for moisture absorption studies. The moisture desorption studies were carried out in a temperature oven at 45° C and 85° C. The mechanical properties of the exposed specimens were evaluated during absorption and desorption conditions. Scanning Electron Microscopy (SEM) studies were carried out on the dry and exposed specimens to determine the effect of moisture on the fracture behaviour of glass-epoxy composites. Results show that, moisture reabsorption and full desorption are faster than the absorption and partial desorption. This may be due to, change of material properties after a cycle of moisture absorption and desorption phenomenon. The mechanical strength (ILSS, compression and flexural) has been found to reduce continuously with increased duration of environmental exposure, but a slight shift back of the strength has been observed for desorbed samples.

Long-Term Behavior of Nanoclay/TiO2 Nanoparticles Modified Carbon/Glass Fiber–Reinforced Hybrid Composites

Abstract Polymer composites are widely used as a primary structural material in lightweight construction industries due to their high strength-to-weight ratio and low cost. However, the mechanical properties get degraded when exposed to adverse environmental conditions. Hybridization of nanofillers and fibers can improve the hygroscopic behavior of polymer composites. In this work, the long-term performance of nanoclay/titanium dioxide–modified carbon/glass-reinforced hybrid composites under a seawater environment was investigated. The specimens were immersed in seawater (100 % relative humidity, 32°C) for 90 days. The effect of moisture absorption on the specimens was evaluated using water absorption, tensile, and flexural tests. Experimental results showed that the addition of nanofillers and carbon/glass hybridization had a significant impact on the water barrier properties and decay in mechanical properties. The residual life of the laminates under humid environmental conditions was predicted using an exponential function. Constituent materials and duration of exposure had a significant impact on the property’s degradation. The test findings showed that the (90°G/0°G/90°C)S sequenced laminate at 2 wt. % of nanofillers had a maximum residual life of 1,619 days under tensile loading and 3,051 days under flexural loading after 90 days of aging.

Investigating long‐term creep in a composite pipe subjected to transverse loading and aqueous condition

AbstractGlass‐fiber reinforced‐polymer (GFRP) pipes are widely used in various applications under wet conditions. Despite the considerable efforts on characterizing the mechanical response of GFRP pipes from various viewpoints in dry condition, less attention has been given to the influence of moisture absorption on their performance. The main goal of this research is to investigate the influence of moisture absorption on the long‐term creep behavior of GFRP pipes experimentally and theoretically. As experimental program, a GFRP pipe is subjected to a constant compressive transverse loading while it is submerged in water. Thus, the interaction between creep and water absorption are studied up to 5000 h. A systematic modeling procedure is also developed to evaluate the long‐term wet‐creep response of the GFRP pipes. Two scales of micro and macro are linked through an explicit modeling procedure. An excellent agreement is observed between experimental observations and outputs of the developed modeling procedure.Highlights A process is developed to model long‐term creep in composites under wet condition. Long‐term creep is predicted based on short‐term creep behavior of pure resin. Long‐term creep on immersed pipe in water under the transverse loading is simulated. Updating constitutive equations, nonlinear viscoelastic behavior is estimated. The effect of moisture absorption on the long‐term creep behavior is investigated.

A Multicontinuum-Theory-Based Approach to the Analysis of Fiber-Reinforced Polymer Composites with Degraded Stiffness and Strength Properties Due to Moisture Absorption

Marine energy generation technologies such as wave and tidal power have great potential in meeting the need for renewable energy in the years ahead. Yet, many challenges remain associated with marine-based systems because of the corrosive environment. Conventional materials like metals are subject to rapid corrosive breakdown, crippling the lifespan of structures in such environments. Fiber-reinforced polymer composites offer an appealing alternative in their strength and corrosion resistance, but can experience degradation of mechanical properties as a result of moisture absorption. An investigation is conducted to test the application of a technique for micromechanical analysis of composites, known as multicontinuum theory and demonstrated in past works, as a mechanism for predicting the effects of prolonged moisture absorption on the performance of fiber-reinforced composites. Experimental tensile tests are performed on composite coupons with and without prolonged exposure to a salt water solution to obtain stiffness and strength properties. Multicontinuum theory is applied in conjunction with micromechanical modeling to deduce the effects of moisture absorption on the behavior of constituent materials within the composites. The results are consistent with experimental observations when guided by known mechanisms and trends from previous studies, indicating multicontinuum theory as a potentially effective tool in predicting the long-term performance of composites in marine environments.

Water absorption behaviour of glass fibre-reinforced polymer composite with clamshell and cenosphere fillers

This article deals with the effect of filler material on the water absorption behaviour of glass fibre-reinforced polymer (GFRP) composites. The fillers are cenosphere and clamshell which are industrial waste and marine waste, respectively. The composite with six layers of fibre is prepared using the most common way of hand lay-up process. Different contents of filler, that is, 0, 10 and 20 wt.% of clamshell and cenosphere are added in the glass fibre-epoxy polymer. These are the wastes that have the potential to be an important filler in polymer matrix composite (PMC). The water absorption behaviour of the glass composites is studied and found that filler content plays a significant role in the water absorption property. The addition of both fillers improves the water resistance of the composites. The diffusion mechanism of water absorption of the present composites follows the non-Fickian type. Composites with cenosphere filler show better water resistance when compared to composites with clamshell filler. The effect of moisture absorption on the tensile strength of composites is also investigated which shows that the tensile strength of the composites is degraded after water immersion. The degradation of the tensile strength in the composite is lower in the case of saline water when compared to distilled water. Tensile strength of the composite is increased with the addition of filler and is highest in glass fibre-epoxy composite at 20 wt.% for both clamshell and cenosphere fillers. 20 wt.% of clamshell filler in the composite shows better tensile strength when compared to 20 wt.% of cenosphere in the composite.

Damping of micro- and nanocellulose reinforced PA610 composites and influences of moisture absorption

Composites consisting of bio-based polyamide 610 (PA610) reinforced with micro- and nano-cellulose were manufactured by melt compounding followed by injection molding. The resulting composites had fiber sizes ranging from nanoscale to 100 µm at 2.5 %, 5 % and 10 % fiber mass fractions. These composites were mechanically characterized by tensile tests followed by scanning electron microscopy to examine the tensile fracture surface. The primary focus of the work was the damping behavior of these nanocomposites, which was found to be substantial. Damping was characterized using the damping ratio extracted from the measured decay of mechanical vibrations. Cellulose nanocrystal-reinforced PA610 at 10 % mass fraction was found to produce a 210 % increase in damping ratio compared to control PA610. Larger fiber sizes and lower mass fractions resulted in smaller, but significant, increases in damping. Comparison to cellulose reinforced polypropylene composites showed that PA610/cellulose composites produced significantly greater relative damping. Additionally, since both cellulose and PA610 are hydrophilic materials, a study was made on the effects of moisture absorption on the damping. It was found that the pronounced effect of the filler on damping was diminished by absorbed moisture and did not return after removing moisture from the samples. The origin of the damping increase and the effects of moisture were discussed in the article.

Effect of moisture absorption on the thermo-mechanical properties of carbon/epoxy composites with SiC reinforcement

ABSTRACT Carbon fiber reinforced polymer (CFRP) composites have many applications in civil engineering, aircraft industry and in many other areas. They are lightweight composite materials with outstanding mechanical properties. In this study, the testing specimens were made from the carbon fabrics impregnated with epoxy resin which had been reinforced with the silicon carbide (SiC) microparticles or SiC microfibers. The four-layered composite samples were fabricated by means of hot compression and curing of epoxy resin. The thermal, tensile and impact properties of the untreated specimens were compared with the ones that underwent the water absorption in duration of 72 hours, followed by desorption. The treated specimens containing the SiC particles and SiC microfibers demonstrated 3.4% and 8.8% of the reduction in the tensile energy absorption, correspondingly, compared to their untreated counterparts. Opposed to this trend of results, the tensile energy absorption value of the treated carbon/epoxy specimens, experienced an increase of 84.4% compared to the dry carbon/epoxy specimens. The additional test results showed that the water treated carbon/epoxy composites went into a certain decline in their thermal, tensile and impact properties. The obtained results provide some significant pieces of information for the future practical use of the presented composites.