Effect Of Water Aging Research Articles

Water Diffusion in Additively Manufactured Polymers: Analysis of the Capillary Effect

Additive manufacturing (AM) is an advanced manufacturing method that produces objects by sequential layering. Material extrusion AM (MEAM) with continuous-fibre reinforcement is becoming more widely used in naval structures, which are exposed to the marine environment. However, the water diffusion process and the effect of water ageing on the mechanical performance of AM materials are not yet well understood because of their complex internal structure, caused by defects generated during manufacturing. Current research on diffusion is mostly based on experimental methods for conventionally manufactured materials without considering AM-induced defects. The objective of this study is to explore how the defects inherent to MEAM affect water diffusion in a composite material by the capillary effect. Results from a numerical study of capillary flow in MEAM polymer are applied as a boundary condition in the subsequent finite-element analysis. The study illustrates that flow in the capillary reaches the steady state quicker compared to the saturation time in the matrix, predicted by Fick’s diffusion equation. It is demonstrated that the capillary effect can significantly affect the water diffusion in MEAM parts and reduce the saturation time to one-third compared to the case without accounting for this effect.

Effect of water ageing on mechanical performance of Kenaf/PLA bio-composites

Effect of water ageing on mechanical performance of Kenaf/PLA bio-composites

Effects of chitosan and TiO2 nanoparticles on the antibacterial property and ability to self-healing of cracks and retrieve mechanical characteristics of dental composites

The aim of this study was to improve the self-healing properties of dental nanocomposite using nanoparticles of TiO2 and chitosan. We evaluated flexural and compressive strength, crack-healing, and self-healing lifespan after 3 months of water aging. The effect of the developed composite on cell viability and toxicity was assessed by an MTT assay on human alveolar basal epithelial cells (A549 cell line). The nanocomposite included 7.5 wt% polyurea-formaldehyde (PUF) and 0, 0.5, and 1 wt% n-TiO2 and chitosan. After the fracture, the samples were put in a mold for 1–90 days to enable healing. Then, the fracture toughness of the healed nanocomposites and the healing yield were measured. The flexural strength of the nanocomposite improved by adding 0.5 wt% n-TiO2, while the compressive strength increased after adding 0.5 wt% chitosan (p > 0.1). When these two materials were used simultaneously, the flexural strength was improved by around 2%; however, the compressive strength was unaffected. Compared to the other sample, the nanocomposite with 0.5 wt% n-TiO2 and chitosan had higher KIC-healing and self-healing efficiency. Self-healing efficacy had no significant effect of water aging over 90 days compared to one day (p > 0.1), demonstrating that the PUF nanocapsules were not damaged.

Impact of water diffusion on electrical properties of epoxy nanocomposites

This study investigates the effects of water ageing at 80 °C on glass fibre hybrid epoxy nanocomposites with multi-walled carbon nanotubes and graphene nanoplatelets. Effect of water uptake in the epoxy matrix is mitigated by the inclusion of carbon nanofillers, leading to improved hydrophobic nature. A comparative study is performed on the water uptake of the epoxy-amine matrix cured with aliphatic amine, with 0.4 weight percent of MWCNT and 0.6 weight percent of graphene nanoplatelets (GNPs). Gravimetric assessment and electrical impedance measurements are carried out over a period of 3000 h to assess water diffusion coefficients and water saturation. Water absorption is measured until saturation, and results show that the water diffusion coefficient of the hybrid nanocomposites is increased from 2.51 × 10−8 (m2 s−1) at 27 °C to 3.32 × 10−8 (m2 s−1) at 80 °C and it is higher than that of the base epoxy composites. Cole–Cole diagrams have revealed heterogeneity of the composites studied. Water diffusion results in the plasticization of the matrix, and it manifests in the broadening of the tanδ peak observed in water-aged epoxy composites. With the inclusion of hybrid MWCNT and GNP nanofillers.,the water diffusion coefficient is reduced to half, and saturation is increased by four times.

Effect of graphene nanoplatelets on mode I fracture Toughness of epoxy adhesives under water aging conditions

ABSTRACT In this work, graphene nanoplatelets (GNP) are used to reinforce epoxy adhesives, and the effects of GNP on mode I fracture toughness of adhesive under water aging condition are studied through double cantilever beam (DCB) test. Although the GNP reinforced adhesives deliver slightly higher GIC than neat epoxy before water aging, they exhibit an exceptional 21.93% higher GIC after immersing in water for 56 d, at a GNP content of 0.25 w.t.%. According to the experimental results, the effectively dispersed GNP could significantly alleviate the degradation rate in mode I fracture toughness due to the water aging. For example, compared to the non-aging condition, the mode I fracture toughness of neat epoxy decreases by 29.19% after 56 d of water aging. In a stark contrast, the degradation rate for 0.25 w.t.% GNP reinforced adhesive is only 15.76%. In addition, it is observed that GNP greatly improves the fracture surface roughness of DCB samples, which suggests that the incorporation of GNP is able to delay the negative effect of water aging on mode I fracture toughness of adhesive by lowering the diffusion of water into the adhesive, while increasing torturous of the crack propagation path.

Effect of water aging on the shear bond strength of different self-adhesive restorative materials to dentin

This study aimed to evaluate the effect of water aging on the shear bond strength of four self-adhesive restorative materials on dentin. Sixty permanent human molars recently extracted for prophylactic purposes were used in this study. The crown of each tooth was cut under water-cooled conditions using a plaster cutting engine to expose the middle dentin surface of the teeth. The prepared teeth were randomly divided into six groups according to the restorative materials [KERR Vertise Flow (VF), GC EQUIA Forte (EQ), PENTRON Fusio Liquid Dentin (PF), IMICRYL Nova Compo SF (NC) Clearfil Majesty ES-2 (CM-control) and Clearfil Majesty ES Flow (CF-control)]. Each restorative material was applied to two different areas of each tooth (n = 120) using cylindrical silicone molds with dimensions of 2 mm × 2 mm. Macro-shear tests were conducted using a Universal Testing Machine (1 mm/min) initially (24 h) and after aging (6 months of water aging), and the failure types were analyzed. For the initial values, a significant difference in the shear bond strength of the self-adhesive and control groups was observed. After aging, the bond strength increased for flowable composite material (CF) and decreased for two different self-adhesive restorative material groups (NC and EQ). There was no significant difference in the bond strength before and aging in the paste-like control composite group (CM) and in the two self-adhesive restorative material groups (VF and PF). Differences in the shear bond strength were observed between the self-adhesive and control materials both before and after aging.

The effect of water aging on the repair shear bond strength of current resin composites

The effect of water aging on the repair shear bond strength of current resin composites

Static and Fatigue Tensile Behavior and Damage Mechanisms Analysis in Aged Flax Fiber/PLA Composite

The aim of this paper is to analyze the effect of water aging of flax/PLA composites on their mechanical characteristics and damage mechanisms. The composites were manufactured with three-dimensional (3D) printer using bio-based material which is polylactic acid reinforced with flax fiber. The composites studied were subjected to water immersion at room temperature and tested in static and fatigue tensile tests for different immersion times. During mechanical tests, the acoustic emissions (AE) method was utilized to identify the emergence of damage processes and to track their evolution. Moreover, macroscopic and microscopic data were used to study damage processes. To confirm the reality of the damage mechanisms observed, microscopic data were linked with acoustic emission classes. Two types of events were observed by acoustic emissions associated with two composite damage mechanisms. Young’s modulus and stress decreased with aging, according to static testing. However, there was an increase in the strain. Strength and damping properties of unaged and aged composites were investigated using fatigue tensile tests. The results showed that water uptake induced a decrease in strength and stiffness and an increase in damping when compared in terms of aging time. There was also a reduction in useful life as immersion time increased.

The Effect of Water Aging on Shear Bond Strength of Pretreated Zirconia-Oxide Ceramics Bonded to Resin Cement – An In Vitro Study

Background and Aim Use of zirconia oxide based ceramic system has become increasingly popular in dentistry because of zirconiarsquos esthetic and mechanical properties and its biocompatibility. Success of ceramic esthetic restoration depends on achievement of high retention and fracture resistance after cementation. Micro chemical retention can be achieved by various surface treatments. There are reports stating that long term presence of moisture decreases the physical properties of material and increases the risk of failure. Aging leads to changes in behaviour of material weakening it and subsequently degrading the material. This study investigated the phenomenon of aging of zirconia-resin by thermocycling in order to assess the problems related to its use and effect on shear bond strength of zirconia by bonding with cement.Method Twelve zirconia discs were taken and were divided into three groups having four discs each. Five resin cylinders were built on each disc. Group A was sandblasted which served as control group. Group B was exposed to hot etching using methanol 800 mL 37 HCl 200 mL and Ferric chloride 2 gm at 100 degC. Group C involved applying a layer of zirconia primer. After surface treatment two discs from each group were exposed to 500 thermocycling cycles simulating the oral environment. The shear bond strength testing was done following this. One way ANOVA test and Tukeyrsquos Post Hoc analysis were performed.Result Zirconia primer showed the maximum strength with and without exposure to thermocycling.Conclusion Zirconia primer proved to be a more effective surface treatment.nbsp

Effect of hydric aging on the static and vibration behavior of 3D printed bio-based flax fiber reinforced poly-lactic acid composites

Moisture accumulation and life span in a hydric setting are major concerns for natural fibers used for the reinforcement of bio-based composites. This article discusses the effect of water aging on the mechanical properties of poly-lactic acid composites reinforced with flax fibers produced by 3D printing. Water absorption of composites is measured and it was observed that the bio-based composite seems to be Fick’s model with a percentage of absorption at saturation equal to 1.2%. To determine the effect of water absorption on static and vibration mechanical properties, various immersion periods are chosen. Water aging obviously influences the stiffness and tensile failure; so, a decline in the Young’s modulus from 2.2 to 1.7 GPa and in strength from 36 to 30.5 MPa is seen. Nevertheless, the damping factor shows an increase by about 16% as a function of the immersion period. These results could be explained by the plasticizing effect of water on bio-based composites, stimulated by moisture absorption.

Hygrothermal aging and water absorption behavior of radial tire composites

AbstractRadial tires (RT) are widely used in the automobile. However, the moisture absorption characteristics of the tire in the hygrothermal environment accelerate tire aging and affect the service life. This work focused on the water absorption behavior and durability of RT composites in the hygrothermal environment. The effects of aging in water at 30, 60, and 90°C on water absorption, chemical degradation, and internal structure of RT composites were investigated. The results showed that the water diffusion of RT composites followed the Fickian's law of diffusion in the initial stage. The kinetic parameters of water absorption were also determined at this stage and were closely related to the change of temperature. Then, moisture led to the poor interface and the degradation of RT composites. Natural rubber (NR) matrix swelled due to the invasion of water, which developed stresses that could cause microcracks of the matrix in the second stage. Moreover, moisture promoted hydrolysis of the NR matrix and agents in the third stage. The water molecules existed in unbound water and bound water, which made the water diffusion followed the Langmuir adsorption model.

Effect of water aging on the fatigue performance of asphalt binders using the linear amplitude sweep

The fatigue characteristics of asphalt binders after water aging were studied. After undergoing the influence of various aging temperature, humidity and duration, the rheological and fatigue parameters of the binders were obtained through frequency sweep test and linear amplitude sweep (LAS) test. Based on the simplified viscoelastic continuous damage (S-VECD) model, damage characterization, fatigue parameters and fatigue prediction were investigated. The results show that with the temperature, humidity and duration rising, the damage increased significantly and fatigue performance decreased. When the strain was 10%, the change state of fatigue life (Nf) with different water aging conditions was reflected clearly. The damage parameters A and B were the main parameters to determine the fatigue life, and had a linear relationship with the complex modulus and fatigue factor to represent aging dependency, respectively. Also, there was a good consistency (R2 = 0.93) between the predicted Nf and the measured Nf. Therefore, the S-VECD model could effectively predict the fatigue life of the binders after water aging.

Effect of water aging on the anti-biofilm properties of glass ionomer cement containing fluoro-zinc-silicate fillers

A previous study has reported that a novel fluoro-zinc-silicate glass ionomer cement (Caredyne Restore) showed superior anti-biofilm effects by interfering with bacterial adhesion. However, the active ions may degrade with time. This study aimed to assess the valid anti-biofilm effects of Caredyne Restore after being aged by water immersion for 3 weeks. Streptococcus mutans biofilm was allowed to grow on the surface before and after water aging for 24 h using a modified Robbins device flow-cell system. The results showed water aging promoted biofilm formation. Insufficient amount of fluoride and zinc ions were released from Caredyne Restore after water aging under neutral pH condition. An acidic pH is needed to exert effective anti-biofilm properties. As the release of active ions from Caredyne Restore will gradually decrease after the restoration, the restoration may not prevent biofilm formation after 3 weeks while neutral pH is maintained by the buffering capacity of saliva.

Evaluation of water repellency in bentonite filled polypropylene composites via physical and mechanical methods

With the advent of polymeric materials having dimensional stability, outdoor applications for polymer composites are increasing expeditiously. The employment of durable material in wet environments is the most effective means of water repellency. Silane modification was applied to bentonite clay for the donation of hydrophobicity on its surface. Surface functionalities of powder surfaces were confirmed by FTIR-ATR spectroscopy and SEM techniques. Polypropylene composities involving pristine and modified bentonite powders were produced in bulk and film forms at three different loading ratios. Water permeability of bulk and film samples was evaluated via water absorption test. In addition to water uptake values, optical microscopy was utilized in order to visualize the structural deterioration of composite samples after water immersion. Mechanical behaviours of composite materials before and after water absorption test were reported in order to analyze the effect of water aging. Based on the findings, in-depth discussions were performed by comparison with basic models postulated regarding migration of water molecules into polymer structure.

Influence of Water Ageing on Mechanical Performance of Glass Fiber Reinforced Polyester (GFRP) nanocomposites

The current paper discusses about the effect of water ageing on mechanical properties of unfilled and nano-SiC filled Glass/Polyester (G-P) composites. G-P and its nanocomposites were synthesized using hand layup technique followed by compression moulding curing process. Kinetics of water absorption undergoing in each composites has been studied. Results showed that addition of nanofiller in pure G-P composites reduces the water uptake after attending its equilibrium level. Mechanical properties of the moisture absorbed sample exhibited low strength compared to dry or unexposed composites. In overall, amongst the fabricated composites, 4.5 wt.% nano-SiC Filled G-P composites showed better mechanical properties.

Evaluation of antimicrobial property of modified acrylic resin-containing cetylpyridinium chloride.

OBJECTIVE:To evaluate the antimicrobial property of cetylpyridinium chloride (CPC) when polymerized with cold cure acrylic and to assess the duration of its release from modified acrylic.MATERIALS AND METHODS:CPC was added in different concentrations (0%, 2.5%, 5%, and 10%) to cold cure acrylic resin and 180 acrylic discs were prepared. These were divided into four groups of 45 each depending on the concentration of CPC. The antimicrobial property of the modified acrylic for Streptococcus mutans was tested using disc diffusion assay in agar. The duration of release of CPC from self-cure acrylic was tested with optical density reading of solutions by ultraviolet spectrophotometer. The effect of addition of CPC on diametral tensile strength (DTS) of acrylic was tested using UTM (Instron) and the effect of water aging on modified acrylic was compared with unaged specimens.RESULTS AND CONCLUSION:The normality of the data was checked by Shapiro–Wilktest, and as the data failed to show normal distribution, inferential statistics were performed using nonparametric tests of significance. Antimicrobial activity of modified acrylic increased with increase in CPC concentration. Greatest CPC release was observed on the seventh day with a decrease in release from 7 to 180 days. There was a decrease in the diametral strength of the modified resin and water aging had a significant effect on the DTS of the modified resin.

Effect of water aging on the mechanical properties of flax fiber/bio‐based resin composites

ABSTRACTPresent work investigates the effect of hydrothermal aging of flax fiber‐reinforced bio‐based epoxy resin laminates on the mechanical and thermomechanical properties of the composites. Three different types of bio‐based resins were used. Plates reinforced with eight layers plain weave flax fibers of 150 g/m2, manufactured using Resin Transfer Molding (RTM), compression molding or autoclave technique depends on type of the resin. One dimensional Fickian behavior shows a good fitting to the experimental data derived from weight measurements. The water uptake at the equilibrium state in the case of 60 °C temperature was slightly greater than that at 40 °C. The mechanical properties after hydrothermal aging show a significant reduction and do not return to their initial values even after the drying process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48787.

Durability of Basalt/Hemp Hybrid Thermoplastic Composites.

The Achilles heel of thermoplastic natural fibre composites is their limited durability. The environmental degradation of the mechanical properties of hemp and hemp/basalt hybrid-reinforced high-density polyethylene (HDPE) composites has been investigated with a special focus on the effects of water ageing and accelerated ageing, including hygrothermal and UV radiation. Modification of the matrix was carried out using a maleic anhydride high-density polyethylene copolymer (MAPE) as a compatibilizer. Hybridization of hemp fibres with basalt fibres and the incorporation of MAPE were found to significantly decrease the water uptake (up to 75%) and increase the retention of mechanical properties after accelerated ageing. Secondary crystallization phenomena occurring in the composites, as confirmed by differential scanning calorimetry (DSC) analysis, were able to counteract the severe combined effects of hygrothermal stress and UV radiation, with the exception of hemp-fibre composites where permanent damage to the fibres occurred, with 2% and 20% reduction in tensile strength and modulus, respectively, for a 30 wt % hemp fibre-reinforced HDPE.

The effects of water ageing on the tensile static and fatigue behaviors of greenpoxy–flax fiber composites

This work presents the experimental results of the effect of water ageing in flax fibers reinforced greenpoxy resin matrix composite materials. The experimental study was carried out on two cross-ply laminates ([0/90]s and [+45/−45]s). First, the water uptake of the two composite materials was studied. Second, the mechanical properties were identified as a function of the immersion time. The results obtained show that the Young's modulus of composites decreases progressively to 26% for [0/90]s specimens and 46.36% for [+45/−45]s specimens after 30 days of ageing. Finally, the effects of interactions between water ageing and cyclic fatigue behavior were studied. We consider stiffness loss, hysteresis curves, energy dissipation and loss factor versus number of cycles as a function of different immersions time. A significant decrease in the mechanical characteristics of the composites as a function of the immersion time is observed. [+45/−45]s specimens are more sensitive to both fatigue and water ageing phenomena.

Hygrothermal aging and structural damage of a jute/poly (lactic acid) (PLA) composite observed by X-ray tomography

Biodegradable plant fiber reinforced poly (lactic acid) (PLA) composites are potential replacements for traditional synthetic fiber reinforced composites. These may experience hygrothermal aging from the combined effects of moisture and heat. The effects of aging in water at 50 °C on water absorption, chemical degradation of the fibers and matrix, and the tensile properties of a jute fiber/PLA composite have been correlated with changes in the internal structure, observed by high-resolution computed X-ray tomography. Water absorption during aging causes fiber/matrix interface failure and then matrix embrittlement, and these are detrimental to the tensile strength, stiffness and ductility.