scholarly journals Effect of Immersion in Water or Alkali Solution on the Structures and Properties of Epoxy Resin

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1902
Author(s):  
Bin Wang ◽  
Dihui Li ◽  
Guijun Xian ◽  
Chenggao Li
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Free Volume ◽  
Water Uptake ◽  
Water Immersion ◽  
Alkali Solution ◽  
Molecular Chain ◽  
Hydrolysis Reaction ◽  
Resin Matrix ◽  
Structures And Properties

The durability of fiber-reinforced polymer (FRP) composites is significantly dependent on the structures and properties of the resin matrix. In the present paper, the effects of physical or chemical interactions between the molecular chain of the epoxy resin matrix and water molecules or alkaline groups on the water absorption, mechanical structures, and microstructures of epoxy resin samples were studied experimentally. The results showed that the water uptake curves of the epoxy resin immersed in water and an alkali solution over time presented a three-stage variation. At different immersion stages, the water uptake behavior of the resin showed unique characteristics owing to the coupling effects of the solution concentration gradient diffusion, molecular hydrolysis reaction, and molecular segment movement. In comparison with the water immersion, the alkali solution environment promoted the hydrolysis reaction of the epoxy resin molecular chain. After the immersion in water or the alkali solution for one month, the water uptake of the resin was close to saturate, and the viscoelasticity was observed to decrease significantly. The micropore and free volume space on the surface and in the interior of the resin gradually increased, while the original large-scale free volume space decreased. The tensile strength decreased to the lowest point after the immersion in water and the alkali solution for one month, and the decrease percentages at 20 °C and 60 °C water or 60 °C alkali solution were 24%, 28%, and 22%, respectively. Afterward, the tensile strength recovered with the further extension of immersion time. In addition, it can be found that the effect of the alkali solution and water on the tensile strength of the epoxy resin was basically the same.

Mechanical Properties and Microstructure of Aramid/Al2O3/Epoxy Resin Laminated Composites

2008 ◽  
Vol 55-57 ◽  
pp. 389-392
Author(s):  
Supreyak Kumfu ◽  
Wim Nhuapeng ◽  
Wandee Thamjaree ◽  
Tawee Tunkasiri
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Epoxy Resin ◽  
Laminated Composites ◽  
Scratch Resistance ◽  
Resin Matrix ◽  
Sem Images ◽  
Laminate Composites ◽  
Al2o3 Powder ◽  
Casting Technique

Aramid/Al2O3/epoxy resin laminated composites were fabricated using ultrasonic mixing and casting technique. This novo material could be exhibited to the ideal mechanical properties such as high tensile strength, hardness, flexural strength and lightweight which may be used to replace metal parts in vehicles. Moreover, Al2O3 powder was mixed to epoxy resin to improve the scratch resistance. To improve the bending force and interaction between Al2O3 powder phase and epoxy resin phase, the ultrasonic mixing was used for fabricating these laminate composites. The physicals and mechanical properties such as density, hardness, impact test, wear resistance and tensile strength of the composites samples were investigated. It was found that the amounts of percent by volume of the Al2O3 have affected the properties of the laminated composites. Furthermore, microstructures of specimens were also investigated by scanning electron microscope (SEM). From the results, SEM images showed good distribution and adhesion between reinforced phase and epoxy resin matrix phase.

scholarly journals Water Absorption, Hydrothermal Expansion, and Thermomechanical Properties of a Vinylester Resin for Fiber-Reinforced Polymer Composites Subjected to Water or Alkaline Solution Immersion

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 505 ◽  
Author(s):  
Xiaoli Yin ◽  
Yancong Liu ◽  
Yufei Miao ◽  
Guijun Xian
Keyword(s):  
Water Uptake ◽  
Alkaline Solution ◽  
Elevated Temperatures ◽  
Water Immersion ◽  
Thermomechanical Properties ◽  
Fiber Reinforced Polymer ◽  
Molecular Networks ◽  
Resin Matrix ◽  
Fiber Reinforced ◽  
Reinforced Polymer

In the present paper, a vinyl ester (VE) resin, potentially used as a resin matrix for fiber-reinforced polymer (FRP) composite sucker rods in oil drilling, FRP bridge cables, or FRP marine structures, was investigated on its resistance to water and alkaline solution immersion in terms of water uptake, hydrothermal expansion, and mechanical properties. A two-stage diffusion model was applied to simulate the water uptake processes. Alkaline solution immersion led to a slightly higher mass loss (approx. 0.4%) compared to water immersion (approx. 0.23%) due to the hydrolysis and leaching of uncured small molecules (e.g., styrene). Water immersion caused the expansion of VE plates monitored with Fiber Bragg Grating (FBG). With the same water uptake, the expansion increased with immersion temperatures, which is attributed to the increased relaxation extent of the resin molecular networks. Although an obvious decrease of the glass transition temperatures (Tg) of VE due to water immersion (5.4 to 6.1 °C/1% water uptake), Tg can be recovered almost completely after drying. Tensile test results indicate that a short-term immersion (less than 6 months) enhances both the strength and elongation at break, while the extension of the immersion time degrades both the strength and elongation. The modulus of VE shows insensitive to the immersion even at elevated temperatures.

Composite Technology in Couplings and Shafting for Power Transmission

1992 ◽  
Author(s):  
Thomas G. Fromknecht
Keyword(s):  
Tensile Strength ◽  
Corrosion Resistance ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Composite Structures ◽  
Power Transmission ◽  
Filament Winding ◽  
Mechanical Power ◽  
Resin Matrix ◽  
Composite Shaft

Abstract Composite technology is growing in the power transmission industry. Composite structures of predominately carbon fibers and epoxy resins form a matrix structure for which one use is to transmit mechanical power. Of significant importance in this paper is the use of composite structures for shafting and coupling flexible elements. Filament wound composite shafting consists of winding a continuous band of the carbon fiber and epoxy resin matrix around a mandrel to obtain optimized end product characteristics. These optimized characteristics include: minimized weight with superior tensile strength when compared to steel, variable modulus of elasticity for critical speed requirements, virtually no thermal expansion of the composite shaft and corrosion resistance. The ability to modify the wind angles during the manufacture of the composite shaft permits the designer to achieve desirable system characteristics through variations in the composite matrix or laminate with negligible change in component cost or delivery. Coupling flexible elements are also manufactured from carbon fiber and epoxy resin laminates. These flexible elements take advantage of the greater tensile strength of the carbon fiber versus carbon or stainless steels to achieve a superior torque capacity within a given coupling outside diameter, or greater power density with equivalent or greater misalignment capacities. The carbon fiber and epoxy resin composite coupling flexible element embodies the desirable coupling characteristics of low deflection stiffnesses resulting in low reaction forces transmitted to the connecting equipment, with minimized possibility of fretting fatigue and significant corrosion resistance. This paper will provide an overview on the composite structure, the materials used, the filament winding process, other manufacturing processes and the application and benefits of this technology in mechanical power transmission.

Durability Performances of Aramid Fiber Reinforced Polymer as Reinforcement Material for Concrete Structures in Cold Regions

2020 ◽  
Vol 853 ◽  
pp. 171-176
Author(s):  
Shuo Zhang ◽  
Chun Lin Liu ◽  
Wen Zhu ◽  
Meng Xiong Tang ◽  
He Song Hu ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
Epoxy Resin ◽  
Aramid Fiber ◽  
Fiber Reinforced Polymer ◽  
Resin Matrix ◽  
Fiber Reinforced ◽  
Freeze Thaw ◽  
Dry Air ◽  
Reinforced Polymer

A series of tests were conducted to investigate the mechanical performances of aramid fiber reinforced polymer (AFRP) and its epoxy resin matrix after 0, 20, 40, 60 and 80 freeze-thaw cycles in the dry air, respectively. After a given number of freeze-thaw cycles, the residual tensile strength and elastic modulus of AFRP specimens were measured, and the lap-shear strength of epoxy resin adhesive specimens was gained. Test results show that: (1) Variation of the elastic modulus of AFRP with the increasing of the freeze-thaw cycles exhibits the same tendency as the tensile strength did. They increase in the first 20 to 40 cycles and then decrease till the end of 80 cycles; (2) The tensile strength and elastic modulus of AFRP decreases by 5.1% and 8.2%, respectively, after 80 cycles as compared with that kept in the laboratory environments. However, the effect of the freeze-thaw cycling in the dry air on the tensile properties of CFRP is very limited within 80 cycles; (3) The freeze-thaw cycling in the dry air of this study has an adverse effect on the adhesive property of the epoxy resin, which could be regarded as the evidence for the degradation of the interface between aramid/carbon fiber and matrix.

scholarly journals The Influence of Mixing Methods of Epoxy Composition Ingredients on Selected Mechanical Properties of Modified Epoxy Construction Materials

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 411
Author(s):  
Izabela Miturska ◽  
Anna Rudawska ◽  
Miroslav Müller ◽  
Monika Hromasová
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Construction Materials ◽  
Preliminary Heating ◽  
Epoxy Composition ◽  
Mixing Speed ◽  
Adhesive Composition ◽  
Adhesive Compositions ◽  
The Matrix ◽  
Level Of Significance

The proper process of preparing an adhesive composition has a significant impact on the degree of dispersion of the composition ingredients in the matrix, as well as on the degree of aeration of the resulting composition, which in turn directly affects the strength and functional properties of the obtained adhesive compositions. The paper presents the results of tensile strength tests and SEM microphotographs of the adhesive composition of Epidian 57 epoxy resin with Z-1 curing agent, which was modified using three fillers NanoBent ZR2 montmorillonite, CaCO3 calcium carbonate and CWZ-22 active carbon. For comparison purposes, samples made of unmodified composition were also tested. The compositions were prepared with the use of six mixing methods, with variable parameters such as type of mixer arm, deaeration and epoxy resin temperature. Then, three mixing speeds were applied: 460, 1170 and 2500 rpm. The analyses of the obtained results showed that the most effective tensile results were obtained in the case of mixing with the use of a dispersing disc mixer with preliminary heating of the epoxy resin to 50 °C and deaeration of the composition during mixing. The highest tensile strength of adhesive compositions was obtained at the highest mixing speed; however, the best repeatability of the results was observed at 1170 rpm mixing speed. Based on a comparison test of average values, it was observed that, in case of modified compositions, the values of average tensile strength obtained at mixing speeds at 1170 and 2500 rpm do not differ significantly with the assumed level of significance α = 0.05.

scholarly journals Enhanced Tensile Strength of Monolithic Epoxy with Highly Dispersed TiO2-Graphene Nanocomposites

2021 ◽  
Vol 5 (7) ◽  
pp. 191
Author(s):  
Yanshuai Wang ◽  
Siyao Guo ◽  
Biqin Dong ◽  
Feng Xing
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Mechanical Performance ◽  
Chemical Properties ◽  
High Mechanical Property ◽  
Graphene Nanocomposites ◽  
Highly Dispersed ◽  
Dispersion State ◽  
Physical And Chemical

The functionalization of graphene has been reported widely, showing special physical and chemical properties. However, due to the lack of surface functional groups, the poor dispersibility of graphene in solvents strongly limits its engineering applications. This paper develops a novel green “in-situ titania intercalation” method to prepare a highly dispersed graphene, which is enabled by the generation of the titania precursor between the layer of graphene at room temperature to yield titania-graphene nanocomposites (TiO2-RGO). The precursor of titania will produce amounts of nano titania between the graphene interlayers, which can effectively resist the interfacial van der Waals force of the interlamination in graphene for improved dispersion state. Such highly dispersed TiO2-RGO nanocomposites were used to modify epoxy resin. Surprisingly, significant enhancement of the mechanical performance of epoxy resin was observed when incorporating the titania-graphene nanocomposites, especially the improvements in tensile strength and elongation at break, with 75.54% and 176.61% increases at optimal usage compared to the pure epoxy, respectively. The approach presented herein is easy and economical for industry production, which can be potentially applied to the research of high mechanical property graphene/epoxy composite system.

scholarly journals Effect of Water Ingress on the Mechanical and Chemical Properties of Polybutylene Terephthalate Reinforced with Glass Fibers

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1261
Author(s):  
Catarina S. P. Borges ◽  
Alireza Akhavan-Safar ◽  
Eduardo A. S. Marques ◽  
Ricardo J. C. Carbas ◽  
Christoph Ueffing ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Water Uptake ◽  
Significant Influence ◽  
Water Immersion ◽  
Water Diffusion ◽  
Polybutylene Terephthalate ◽  
Chemical Changes ◽  
Water Ingress ◽  
Effect Of Water

Short fiber reinforced polymers are widely used in the construction of electronic housings, where they are often exposed to harsh environmental conditions. The main purpose of this work is the in-depth study and characterization of the water uptake behavior of PBT-GF30 (polybutylene terephthalate with 30% of short glass fiber)as well as its consequent effect on the mechanical properties of the material. Further analysis was conducted to determine at which temperature range PBT-GF30 starts experiencing chemical changes. The influence of testing procedures and conditions on the evaluation of these effects was analyzed, also drawing comparisons with previous studies. The water absorption behavior was studied through gravimetric tests at 35, 70, and 130 °C. Fiber-free PBT was also studied at 35 °C for comparison purposes. The effect of water and temperature on the mechanical properties was analyzed through bulk tensile tests. The material was tested for the three temperatures in the as-supplied state (without drying or aging). Afterwards, PBT-GF30 was tested at room temperature following water immersion at the three temperatures. Chemical changes in the material were also analyzed through Fourier-transform infrared spectroscopy (FTIR). It was concluded that the water diffusion behavior is Fickian and that PBT absorbs more water than PBT-GF30 but at a slightly higher rate. However, temperature was found to have a more significant influence on the rate of water diffusion of PBT-GF30 than fiber content did. Temperature has a significant influence on the mechanical properties of the material. Humidity contributes to a slight drop in stiffness and strength, not showing a clear dependence on water uptake. This decrease in mechanical properties occurs due to the relaxation of the polymeric chain promoted by water ingress. Between 80 and 85 °C, after water immersion, the FTIR profile of the material changes, which suggests chemical changes in the PBT. The water absorption was simulated through heat transfer analogy with good results. From the developed numerical simulation, the minimum plate size to maintain the water ingress unidirectional was 30 mm, which was validated experimentally.

scholarly journals Use of Cement Suspension as an Alternative Matrix Material for Textile-Reinforced Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2127
Author(s):  
Richard Fürst ◽  
Eliška Fürst ◽  
Tomáš Vlach ◽  
Jakub Řepka ◽  
Marek Pokorný ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Epoxy Resin ◽  
High Performance Concrete ◽  
Bending Test ◽  
Resin Matrix ◽  
Cement Matrix ◽  
Sample Type ◽  
Textile Reinforced Concrete ◽  
Epoxy Resin Matrix ◽  
Four Point Bending

Textile-reinforced concrete (TRC) is a material consisting of high-performance concrete (HPC) and tensile reinforcement comprised of carbon roving with epoxy resin matrix. However, the problem of low epoxy resin resistance at higher temperatures persists. In this work, an alternative to the epoxy resin matrix, a non-combustible cement suspension (cement milk) which has proven stability at elevated temperatures, was evaluated. In the first part of the work, microscopic research was carried out to determine the distribution of particle sizes in the cement suspension. Subsequently, five series of plate samples differing in the type of cement and the method of textile reinforcement saturation were designed and prepared. Mechanical experiments (four-point bending tests) were carried out to verify the properties of each sample type. It was found that the highest efficiency of carbon roving saturation was achieved by using finer ground cement (CEM 52.5) and the pressure saturation method. Moreover, this solution also exhibited the best results in the four-point bending test. Finally, the use of CEM 52.5 in the cement matrix appears to be a feasible variant for TRC constructions that could overcome problems with its low temperature resistance.

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