Interface Of Glass Fiber Research Articles

Bond strength analysis of post-installed rebar with chemical adhesive in concrete mixed with marble powder and glass fiber

This study investigates the impact of marble powder as a part of fine aggregate and the addition of glass fiber on the bond strength of concrete and deformed high-strength post-installed steel rebars using the epoxy chemical as an adhesive. Five marble dust powder (MDP) substitution percentages (i.e. 0%, 10%, 20%, 30%, and 35%) and the addition of glass fiber (i.e. 0.5%, 1%, and 1.5%) were used. The performance of deformed high-strength post-installed rebars in conventional concrete and concrete modified with 35% marble powder and 1% glass fiber was examined here utilizing pull-out tests on a total of 96 specimens. To examine the bond behaviors of deformed high-strength post-installed rebars at the epoxy–conventional concrete interface and epoxy-modified concrete with MDP and glass fiber interface, test criteria included concrete compressive strength, anchorage depth of rebar into concrete, rebar diameter, and concrete cover to rebar diameter ratio. For post-installed high-strength deformed rebar, bond stress–slip relationships were determined, examined, and subsequently compared with prior work and readily available codes. It was found that none of the specimens exhibited pull-out failure and that the majority of them displayed concrete splitting, concrete rapture, or rebar rapture failure. This suggests that epoxy resins are particularly successful as bonding agents to retrofit concrete structures at the steel–concrete contact. A closed-form equation for predicting the bond strength for post-installed high-strength deformed rebar was also created using regression analyses on the experimental data. With a significant coefficient of determination (R2 = 0.85) the observed predicted bond strengths and the test data were quite similar.

Effect of temperature and water penetration on the interfacial bond between epoxy resin and glass fiber: A molecular dynamics study

According to the hydrothermal working environment, accidents related to composite insulator string rupture are frequently encountered in transmission line, which cause serious hazard to the stability of power system. The interface between epoxy resin matrix and glass fiber fillers is one of the microscopic interfaces in the insulator core rod. The adhesion strength of that interface has important implications for the overall mechanical properties of the core rod. This study aims to analyze the influence of temperature and water intrusion on the interfacial adhesions. By molecular dynamics (MD) simulation, a molecular modelling of epoxy resin / glass fiber interface under water molecular environment was established. The mechanism of deterioration is indicated through the interfacial binding energy, ester number, radial distribution function (RDF) and H-bonds number of the interface model. It was found that when the temperature increased to a certain level, the water molecules were easy to migrate to the interface through the holes in the epoxy resin. When the temperature reaches 373 K, the epoxy resin occurs hydrolysis reaction, which will promote the cracking of epoxy resin. Meanwhile, water molecules migrated to the interface can hinder the formation of hydrogen bonds between epoxy resin and glass fiber. Under the synergistic effect of the above factors, water gradually causes the degradation of epoxy resin / glass fiber interface.

Monitoring the interface and bulk self-healing capability of tri-axial electrospun fibers in glass fiber reinforced epoxy composites

Tri-axial electrospun fibers with self-healing capability are fabricated through a direct, one-step tri-axial electrospinning process. They have been designed to have two distinct protective walls to encapsulate epoxy resin and its hardener as healing agents in separate cores. The presence of an extra layer between encapsulated liquid healing agent and outer layer enables the encapsulation of chemically and physically active healing agents, extends the efficiency and life-time of the healing functionality. Tri-axial electrospun healing fibers are incorporated to add self-healing capability into solo epoxy matrix and also utilized as an interlayer between glass fabric mats in glass fiber reinforced composite. Tri-axial electrospun fiber interlayers provide self-healing functionality at the interface of glass fibers with epoxy matrix, which is highly prone to failure. In addition, various structural health monitoring and non-destructive testing techniques coupled with traditional mechanical testing methods are employed to evaluate the self-healing efficiency of composite structures. In this study, successful and recurring self-healing ability of composite structures at the interface of glass fiber with the epoxy matrix are achieved and confirmed using different characterization techniques.

Prediction of Deterioration Rate for Composite Material by Moisture Absorption

If the fiber reinforced plastic is exposed to the moisture for a long period of time, most of moisture absorption occurs on the resin place, thus dropping cohesiveness between the molecules as the water molecules permeated between high molecular chains grant high molecular mobility and flexibility. Also as the micro crack occurs due to the permeation of moisture on the interface of glass fiber and epoxy resin, it is developed to the overall damage of interface place. Hence, the study on absorption is essential as the mechanical and physical properties of fiber reinforced composites are reduced.<BR> However, the study on absorption has the inconvenience needing to expose composite materials to fresh water or seawater for 1 month or up to 1 year. Therefore, this study has exposed fiber reinforced composites to fresh water and has developed a model with an accuracy of 98% after comparing the analysis value obtained by using ANSYS while basing on the experimental value of property decline by absorption and the basic properties of glass fiber and epoxy resin used in the experiment.

HDPE functionalization via high shear stress‐induced initiation and its effects on HDPE/GF composite

AbstractThe functionalization reaction of high density polyethylene (HDPE) with maleic anhydride (MAH) or with MAH and γ‐methacryloxy‐propyltrimethoxysilane (MAS) performed in melt state through a high shear stress‐induced initiation by increasing the screw rotation speed of twin‐screw extruder and through a compounded initiation by adding some initiator and increasing the screw rotation speed was investigated in this article. The results show that by increasing the screw rotation speed during melt‐extruding process, the scission of HDPE chain bonds can be caused to form macroradicals, the functionalization reaction of HDPE with MAH or with MAH, and MAS can be realized. The percentage of grafting and the melt flow rate of the functionalized products depend on the screw rotation speed and reaction temperature. The crosslinking reaction during melt extrusion can be suppressed by increasing the screw rotation speed and the reaction of HDPE with MAH can also be promoted by adding a second grafting monomer MAS. The high shear stress‐induced reaction products have a higher reactivity with the coupling agents coated on the surface of glass fibers and can obviously increase the mechanical properties of HDPE/GF composite. The SEM experimental results indicate that an oriented crystal transition layer exists between the interface of glass fiber and the matrix, the interfacial bonding strength is the determining factor of the formation of the oriented crystal layer. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Functionalization of high density polyethylene in melt state through ultrasonic initiation and its effect on mechanical properties of glass fiber reinforced composites

Functionalization reaction of high density polyethylene (HDPE) with γ-methacryloxy-propyltrimethoxysilane (MAS) or with MAS and MAH performed in melt state through ultrasonic initiation by a laboratory-scale ultrasonic extruding reactor was studied in this paper. The effect of ultrasonic intensity on the percentage of grafting and melt flow rate of the functionalized products was investigated. The results show that by imposing ultrasonic vibration during melt-extruding process, the scission of HDPE chain bonds can be caused to form macroradicals, the functionalization reaction of HDPE with MAS or with MAS and MAH can be realized. The percentage of grafting and the melt flow rate of the functionalized products depend upon the ultrasonic intensity and reaction temperature. The fuctionalization reaction of HDPE with MAS can be promoted by adding a second grafting monomer MAH. The ultrasonic-induced products have a higher reactivity with the coupling agents coated on the surface of glass fibers, the mechanical properties of the composite improved by the ultrasonic induced product are higher than that of by peroxide initiated product and the mechanical properties of HDPE/GF composite modified by HDPE-g-MAH-MAS are higher than that of by HDPE-g-MAH. The SEM experimental results indicate that an oriented crystal layer exists between the interface of glass fiber and the HDPE matrix, the interfacial bonding strength is the determining factor of the formation of the oriented crystal layer.

Curing of polymer matrix composites: Fluorescence study of dansyl fluorophore labeled to glass fibers and DGEBA–ethylenediamine epoxy resin

Curing process of diglycidyl ether of bisphenol A/ethylenediamine mixture in the presence of glass fibers was monitored by fluorescence in two ways: first, using dansyl labeled glass fibers and diglycidyl ether of bisphenol A (DGEBA)/ethylenediamine mixture and second, using unlabeled glass fibers and DGBA-dansyl labeled/ethylenediamine mixture. Integral fluorescence intensity was analyzed as a function of time. Results allow comparison between the curing process inside the bulk of the resin and at the glass fiber interface. It was concluded that for the system DGEBA/ethylenediamine the polymer matrix viscosity increases with the curing time faster inside the bulk than at the glass fiber interface.

Effect of Aging on Interfacial Properties of Glass Fiber Reinforced Concrete

AbstractThis paper explores the behavior of the interface of glass fiber and cementitious matrix under the effect of aging. Pull-out tests of multiple alkali resistant glass fiber strands embedded in portland cement paste matrix were conducted. Four different curing regimes of 3 and 14 days normal curing, in addition to 3 and 7 days accelerated aging were employed. A recently developed method of characterizing interfacial properties was used to identify and evaluate the important parameters at interface. The experimental data are presented on the parameter of shear stiffness of a fiber-matrix boundary layer, the shear bond strength, the frictional bond strength and the specific surface energy as a function of fiber embedded length. It was observed that aging had a larger effect on the stiffness of the interface, the shear bond strength and the specific surface energy than on the frictional bond.