Influence Of Moisture Absorption Research Articles

The Influence of Moisture Absorption and Desorption by the ABS Filament on the Properties of Additively Manufactured Parts Using the Fused Deposition Modeling Method.

This paper presents the results of research on the influence of the moisture content in a filament made of ABS polymer on the properties of products manufactured using FDM (fused deposition modeling). Tests were carried out on a standard printer, using the parameters recommended by the manufacturer and the literature on the subject. A special climatic chamber was used to condition the material. A negative impact of ABS filament moisture on the strength and dimensional accuracy of printed products and on the structure of their surface is demonstrated. When the range of the filament moisture is between 0.17% and 0.75%, the strength decreases by 25% and the sample thickness increases by 10%. It is also shown that this effect does not depend on the history of the polymer reaching a given moisture level, i.e., by absorbing moisture in the absorption process or releasing moisture in the desorption process.

Influence of moisture absorption on tensile and compressive properties of natural fiber-reinforced thermoplastic composites

ABSTRACT The present research is aimed at examining the changes in tensile and compressive properties of natural fiber-reinforced composites (NFRC) exposed to various humidity conditions; this is due to the fact that moisture content (MC) in fibers is generally assumed to be detrimental to composite performance. It was found that once moisture is exposed, compressive strength and strain of specimens would be higher than those of tensile, whereas modulus of elasticity would be lower. Due to increasing moisture content, although elongation in all tests was enhanced, tensile and compressive strength declined by 15% and modulus of elasticity decreased by 20%. In addition, Poisson’s ratio for both compressive and tensile properties was nearly identical (0.33) in distinct moisture content. A new understanding of moisture’s effects on mechanical behavior is presented in this study by finding an optimum point for exposing moisture to increase compressive and tensile strength.

Influence of moisture absorption on the compressive behavior of halloysite nanotube reinforced buoyant nanocomposite foams for maritime applications

AbstractCurrent research focuses on the development of buoyant nanocomposite foams comprising naturally available nanofiller‐halloysite nanotubes (HNTs). Cenosphere, a waste byproduct of thermal power plants, is used to impart lightweight properties to syntactic foam composites at 0, 20, and 40 vol% in an epoxy matrix. HNTs are added to the cenosphere epoxy syntactic foam (CESF) composites at a constant 1 vol% to improve the favorable mechanical and water absorption properties of the composites. To evaluate the mechanical response of the CESF and HNTs reinforced syntactic foam (HRSF) composites, compression tests are conducted on samples immersed in water. The results of the water absorption analysis on the CESF and HRSF composites conclude that HNTs inhibit the entry of water into the epoxy matrix, resulting in lower absorption values in HRSF samples than in CESF. Outcomes from the compression tests and FTIR study support this conclusion. The modulus value of the water‐immersed HRSF sample with 40% cenospheres (NSF40 W) is reduced by 26.35%, and a 48.52% reduction in the modulus is registered for CESF with a similar concentration without HNTs. Structure–property correlations are established using the crack‐pinning phenomenon and planar dispersion of HNTs depicted by transmission electron microscopy. The HNTs reinforcement shows great promise as a structural, buoyant, and lightweight syntactic nanocomposite foam for maritime applications.

Degradation behaviors of silicone gel encapsulation material with moisture intrusion

In the applications of offshore wind turbines and high-speed trains, the power electronic devices suffer in harsh working conditions of high humidity. The moisture invades devices and induces failure of power modules. Therefore, it is necessary to investigate the degradation behaviors of encapsulation material with moisture intrusion. In this paper, the moisture absorption, chemical, and electrical properties of silicone gel under 85 °C&85%RH with long aging time is characterized. And the aging at 85 °C is chosen as a control. The influence of moisture absorption on the performance of silicone gel is discussed. The results showed that the wettest position locates at the mid-depth in silicone gels after desorption, which can be called as "depth effect" and is first discovered. Besides that, the mass loss during the aging is also observed and a comprehensive explanation considering the competition of absorption and dissolution is given here. Furthermore, a new phenomenon defined as "delayed degradation effect" is discovered. It is that the effect of moisture intrusion on electrical performance degradation in thin samples is delayed. In conclusion, moisture intrusion will degrade the electrical properties of silicone gel, so attention should be paid to power electronic devices working in high humidity conditions.

Stability Analysis of Embankment Slope Considering Water Absorption and Softening of Subgrade Expansive Soil

With the rapid development of road engineering today, a large number of high-grade highways need to pass through expansive soil distribution areas. At present, the research on expansive soil slope mainly focuses on the newly excavated cutting slope. However, according to engineering experience, a landslide of fill embankment on expansive soil foundation is also very common. The expansive soil layer is heterogeneous. There are many weak intercalations or large fissures under the ground, which are generally parallel to the trend, with low strength and high permeability. After rainfall, the strength of the weak interlayer and large fissures will be further reduced after moisture absorption, and the sliding surface is easily formed under the load of filler, which is the main factor inducing embankment landslide. On the basis of landslide investigation and a laboratory test, a FORTRAN calculation program is developed in this paper, which can comprehensively consider the special moisture absorption and softening characteristics of expansive soil. Taking a high fill embankment slope with a soft interlayer in the Baoshan area of Yunnan Province as an example, the stability and instability characteristics of the fill slope on the expansive soil foundation are analyzed, and the influence of moisture absorption and softening on the expansive soil slope is emphatically discussed. Finally, this paper puts forward the reinforcement method of the high fill embankment slope on the soft expansive soil foundation, which is proven to have a good reinforcement effect through calculation analysis and field practice. For expansive soil foundation with weak interlayer, it is better to directly reinforce the weak layer through rigid piles.

Anisotropic behaviors of moisture absorption and hygroscopic swelling of unidirectional flax fiber reinforced composites

This work aims to study the anisotropic moisture absorption characteristics of unidirectional flax fiber reinforced composites (FFRCs) and evaluate the variations of the internal stress caused by the hygroscopic deformation, which might lead to the deterioration of the mechanical properties of the composites. FFRCs were prepared using vacuum-assisted resin infusion molding (VARIM) technology. Moisture absorption tests were designed by sealing the designated surfaces with a polyurethane waterproof coating to keep the moisture absorption of FFRCs only in the desired directions. The deformation caused by moisture absorption in the width direction was also monitored. It confirms that the moisture absorption of FFRCs conformed to the 3D Fick's law, and the influence of moisture absorption in the width direction cannot be ignored, especially for the unidirectional transverse tensile test specimen (UTFRC). The hygroscopic deformation of the unidirectional FFRCs showed that the material expands perpendicular to the fiber direction but shrinks along the fiber direction. The modified 3D Fick’s law based on heat conduction equation was performed to reveal the mechanism of the above moisture absorption and hygroscopic deformation. According to the finite element inversion, it was found that the axial diffusion coefficient along flax fiber bundles was much larger than the transverse diffusion coefficient perpendicular to the fiber bundle direction due to the existence of the unique lumen structure inside flax fibers. In addition, the high internal stress caused by the mismatched swelling properties between the fiber and the matrix was the main reason for the damage of the FFRCs, especially at the interface, which may seriously affect the service life of the composites. The outcome of this study can be used to accurately analyze the hydro-elastic behaviors of plant fiber reinforced composites, which is a prerequisite for predicting the mechanical properties affected by moisture absorption.

Evaluation of the mechanical characteristics of hygrothermally aged 2-D basalt-aramid/epoxy hybrid interply composites

Polymer composites used in outdoor applications are exposed to environmental factors such as temperature and moisture which may affect the mechanical performance of the composites. In this study, the influence of moisture absorption on the mechanical properties of basalt-aramid/epoxy hybrid interply composites were evaluated. Two different types hybrid interply composites were taken for the investigation namely (301 A/03 B/301 A) and (451 A/03B/451 A). Composites were prepared using compression molding process and cut specimens were subjected to three different ageing environments for 180 days. Selected ageing conditions are, (i) ambient temperature ageing (ii) Sub-zero temperature ageing (−10°C) and (iii) Humid temperature ageing (40°C and 60% Relative humidity). Mechanical tests of the aged composites were carried out to analyse the behaviour of the composites. Moisture uptake of the specimens follow Fick’s law of diffusion with saturation absorption of 5.44%, 3.12% and 1.80% for ambient, sub-zero and humid specimens respectively. Results revealed that (301 a/03 B/301 a) aged composites possess higher mechanical properties compared to (451 a/03 B/451 a) aged composites. Highest reduction in properties were observed in ambient aged specimens followed by humid and sub-zero specimens. Scanning electron microscopy (SEM) was employed to observe the damage modes of the fractured specimens. Matrix deterioration, micro cracks and fibre fracture were the major types of failures observed in aged laminates.

Influence of moisture absorption on mechanical properties of kenaf/glass reinforced polyester hybrid composite

The heightened focus on manufacturing of green composites for engineering application and research field, the natural fiber has gained its importance. In the other hand, the hydrophilicity behaviour of natural fiber is a matter of grave concern for their potential outdoor applications. Hence the objective of this work is to study the moisture sorption behaviour of kenaf/glass polyester hybrid composite with diverse stacking sequences in general water medium and its repercussion on mechanical properties. Moisture absorption test was performed by soaking the composite at room temperature into normal water for 20 days. The distinctive parameters such as diffusion coefficient (Dx), moisture content at equilibrium (Mm) and mechanism of water transport were determined. The mechanism of water transport into the hybrid composite was found to follow Fickian’s diffusion. The repercussions of the water sorption on the tensile and bending strength of laminates were investigated. The strengths were found to be decreased with increase in rate of water intake and also the position of kenaf fibre stalk at the outer layer.

Influence of Temperature and Moisture on the Compressive Strength of Carbon Fiber Reinforced Polymers

The effect of moisture absorption and high temperature on the compressive strength of unidirectional IM7/977-2 carbon/epoxy resins have been investigated experimentally. The specimens were divided into 4 groups, and tested under 4 different conditions by varying the testing temperature and moisture parameters. The fiber orientation selected were 0o, ±45o and 90o. The reported results showed that the compressive strength, fracture load and compressive modulus of the specimens were degraded under the influence of moisture absorption and high temperature. The largest compressive strength degradation was observed in the unidirectional specimens. Furthermore, the most severe case was noted for the specimens that were immersed in water and tested at 80°C. The observed reduction in the strength varies depending on the fiber orientation, immersion time and test temperature. The results indicate the importance of considering environmental parameters in designing the composite structures for compression loadings.

The Influence of Moisture Absorption on the Mechanical and Thermal Properties of Chemically Treated DPL Reinforced Hybrid Composite

Moisture absorption of natural fiber-based composites is one of the major problems in outdoor applications. The present study deals with the effect of moisture absorption on mechanical and thermal properties of unmodified/modified Date Palm Leaf (DPL) with glass fiber-based hybrid composites. Natural fibers were modified with alkaline treatment to improve fiber and matrix bonding. Conventional hand lay-up technique is used to fabricate the composites with varying different wt.% of treated and untreated short DPL with constant wt.% of glass fiber and prepared with random oriented manner. The combine effect of hydrophilic and hydrophobic nature find out as the study based upon the natural with synthetic fiber hybrid composites. Mechanical behaviour of the epoxy-based hybrid composites were characterized by using tensile, flexural and hardness test. The results revealed that significant improvement in mechanical properties by the addition of different weight percentage of modified DPL. Different thermal properties of the composites were described by using Thermo Gravimetric Analyzer (TGA) and Differential Scanning Calorimetric (DSC). Morphological investigation was carried out to by using scanning electron microscope. All the properties of untreated natural fiber reinforced composites were mostly affected by the influence of water absorption as compared with chemically treated based composites.

Influence of Water Absorption on the Low Velocity Falling Weight Impact Damage Behaviour of Flax/Glass Reinforced Vinyl Ester Hybrid Composites.

Due to rigorous new environmental legislations, automotive, marine, aerospace, and construction sectors have redirected their focus into using more recyclable, sustainable, and environmentally friendly lightweight materials driven by strengthening resource efficiency drive. In this study, the influence of moisture absorption on flax and flax/glass hybrid laminates is presented with the aim to investigating their low velocity impact behaviour. Three different types of composite laminates namely, flax fibre reinforced vinyl ester, flax fibre hybridised glass fibre and glass fibre reinforced vinyl ester composites were fabricated using resin infusion technique. The moisture immersion tests were undertaken by immersing the different specimens in sea water bath at room temperature and 70 °C at different time durations. The low velocity falling weight impact testing was performed at 25 Joules of incident energy level and impact damage behaviour was evaluated at both ageing conditions using scanning electron microscopy (SEM) and X-ray microcomputed tomography (micro CT). The percentage of moisture uptake was decreased for flax vinyl ester specimens with glass fibre hybridisation. The maximum percentage of weight gain for flax fibre, flax/glass hybrid and glass fibre reinforced composites immersed at room temperature for 696 h is recorded at 3.97%, 1.93%, and 0.431%, respectively. The hybrid composite exhibited higher load and energy when compared flax/vinyl ester composite without hybridisation, indicating the hybrid system as a valid strategy towards achieving improved structural performance of natural fibre composites. The moisture absorption behaviour of these composites at room was observed to follow Fickian behaviour.

Influence of moisture absorption on the degradation of fire-retardant-treated and surface-coated wood

Influence of moisture absorption on the degradation of fire-retardant-treated and surface-coated wood

Influence of moisture absorption on electrical properties and charge dynamics of polyethylene silica-based nanocomposites

The use of nanocomposites as dielectric materials is expected to lead to improved electrical performance. However, recent research has shown that moisture absorption can cause a deterioration in the electrical performance of nanocomposites. Although it is generally accepted that hydroxyl groups attached to nanoparticle surfaces are the main cause of moisture absorption, the impact of this absorption on the electrical properties of nanocomposites is still not fully understood. In this paper, a series of measurements, including thermogravimetric analysis, DC breakdown, surface potential decay and space charge, are conducted with the aim of determining the impact of moisture absorption on the electrical properties of polyethylene/silica nanocomposites. The results show that the loading ratio of nanosilica and the humidity of the conditioning environment determine the amount of absorbed moisture. According to the Zhuravlev model, the main contribution to the deterioration in electrical properties of nanocomposites comes from the large amount of moisture absorbed in multilayer form. It is found that the loading ratio of nanosilica is the most significant factor in reducing DC breakdown strength.

Inverse characterization of vegetable fibre-reinforced composites exposed to environmental degradation

The characterization of composite materials, particularly those reinforced with vegetable fibres, presents additional challenges, like the influence of the manufacturing process, fibre-matrix adhesion problems, progressive stiffness reduction or material degradation due to environmental elements (moisture, heat and UV) exposure.The present work studies the suitability of inverse characterization, based on modal properties, to determine the mechanical properties of jute fibre-reinforced composite plates, subjected to environmental exposure to simulate outdoors application conditions. With this method both the elastic and the damping properties of composite specimens are found, which highlights its great usefulness in the prediction of mechanical properties.It was found that this non-destructive method can better estimate material properties than the rule of mixtures, reflecting manufacturing, processing conditions and also the influence of moisture absorption and UV degradation on the mechanical properties of these natural fibre composites. This method is an important tool since it can be performed in the final parts where the results account for all external influences.

Influence of moisture absorption on the flexural properties of composites made of epoxy resin reinforced with low-content iron particles

In this work, the effect of moisture absorption on the mechanical properties of particulate composite materials is studied. Moisture absorption constitutes a main parameter affecting the thermomechanical behaviour of composites, since it causes plasticization of the polymer matrix with a concurrent swelling. In the present work, the influence of water absorption on the flexural properties of particle-reinforced composites was thoroughly investigated. It was found that during the process of moisture absorption there exists a variation of the flexural properties closely related to the degradation of the mechanical behaviour of the composite, as well as the percentage amount of moisture absorbed. Experiments were carried out with composite made of epoxy resin reinforced with low-content iron particles. The variation of ultimate stress, breaking strain, deflection, elastic modulus and Poisson ratio due to water absorption was examined.

Influence of Moisture Absorption and their Effect on the Physho-Mechanical Properties of Coir-Luffa Fibre Reinforced Polymer Matrix Composites

Influence of Moisture Absorption and their Effect on the Physho-Mechanical Properties of Coir-Luffa Fibre Reinforced Polymer Matrix Composites

Influence of moisture absorption on the impact properties of flax, basalt and hybrid flax/basalt fiber reinforced green composites

Abstract Several studies have been carried out over recent years with the aim of obtaining ecofriendly, biodegradable, low cost, lightweight natural fiber reinforced polymer composites. In this article, two types of natural fibers, basalt and flax, together with their hybridization, have been used to reinforce a green vinyl ester matrix in a wet hand lay-up lamination. The hybrid composite, with flax fiber reinforcement (FFR) in the central zone and basalt fiber reinforcement (BFR) in the outer layers, was intended for construction of boats and yachts. The influence of BFR and FFR on the impact properties of dry and salt-water conditioned composite samples has been investigated. In particular, a comprehensive scanning electron microscope (SEM) analysis of the damaged surface and cross section has been undertaken in order to investigate the mechanisms of energy absorption. The results show significant impact behavior improvements for hybrid composites compared to single composites, especially in the case of conditioned samples.

Weathering and Biodegradation Study on Graft Copolymer Compatibilized Hybrid Bionanocomposites of Poly(Lactic Acid)

This work reports on the influence of moisture absorption and accelerated weathering on the properties of graft copolymer compatibilized bionanocomposites of poly(lactic acid) (PLA). Moisture absorption tests were conducted for 30 days by immersing the samples in a distilled water bath at room temperature, and the amount of moisture absorbed in each time interval was measured. The rate of moisture uptake decreased by incorporation of C30B nanoclay and graft copolymer into fiber-reinforced PLA composites. Changes in the mechanical properties of composites in each time interval of moisture absorption were investigated using tensile and impact tests. Exposure to moisture caused significant drops in the mechanical properties. The morphological characterization of biocomposites during the aforementioned tests has been made using SEM, while bionanocomposites were analyzed by TEM. Further, this paper also reported the effect of accelerated weathering on the mechanical properties and the results are confirmed through SEM analysis. Biodegradation behaviors of PLA biocomposites and bionanocomposites have also been studied.

Experimental study to assess the effect of carbon nanotube addition on the through-thickness electrical conductivity of CFRP laminates for aircraft applications

The present paper tests experimentally the through-thickness electrical conductivity of carbon fiber-reinforced polymer (CFRP) composites laminates for aircraft applications. Two types of samples were prepared: Type A samples with carbon nanotubes (CNTs) and Type B samples without CNTs. During the electrical experiments, electrical currents of several mA were injected through the specimens. Electrical resistance was monitored simultaneously in order to deduce the changes in the through-the-thickness electrical conductivity caused by the addition of CNTs. Improvement of electrical conduction by two orders of magnitude was achieved through the addition of 1 wt% carbon nanotubes as compared to classic CFRP without CNTs. For moisture saturated samples, the influence of moisture absorption on such measures was found to be negligible.

A study on the mechanical behavior of silicone-organically modified montmorillonite composite under human body simulated environment

Abstract Among electroactive polymers (EAPs), dielectric elastomers such as silicone are strong candidate materials for biomimetic actuators. They have several unique abilities such as high deformation and fast response time under applied electric energy. In this study, the basic mechanical properties of the silicone elastomer were measured in a simulated human body environment to investigate the applicability of this material as an artificial muscle in in vivo environment. To enhance the mechanical properties of the silicone elastomer, organically modified montmorillonite (OMMT) particles were added. The silicone–OMMT composite was submerged in 30 °C water for a few weeks to evaluate the influence of moisture absorption on the mechanical properties of the composite. Tensile and creep tests were carried out according to the moisture absorption rate and OMMT particle content. To observe the change of crystalline structure and the level of dispersion of the OMMT in the silicone elastomer matrix, X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were employed.