scholarly journals Strengthening epoxy adhesives at elevated temperatures based on dynamic disulfide bonds

2020 ◽  
Vol 1 (9) ◽  
pp. 3182-3188
Author(s):  
Hsing-Ying Tsai ◽  
Yasuyuki Nakamura ◽  
Takehiro Fujita ◽  
Masanobu Naito
Keyword(s):  
Glass Transition ◽  
Disulfide Bonds ◽  
Epoxy Resins ◽  
Elevated Temperatures ◽  
Adhesive Properties ◽  
Epoxy Adhesives ◽  
Transition Points ◽  
Increasing Temperature

Epoxy resins incorporating aromatic disulfide bonds demonstrated improved adhesive properties with increasing temperature below their glass transition points.

Preparation and Properties of the Underwater Curing Epoxy Adhesives*

2012 ◽  
Vol 580 ◽  
pp. 564-568
Author(s):  
Jian Jun Xie ◽  
Kai Huang ◽  
Qing Xin Yao ◽  
Chu Ding
Keyword(s):  
Adhesive Strength ◽  
Epoxy Resins ◽  
Orthogonal Experiment ◽  
Sheet Steel ◽  
Charpy Impact ◽  
Epoxy Adhesive ◽  
Weight Retention ◽  
Adhesive Properties ◽  
Epoxy Adhesives ◽  
Underwater Concrete

The epoxy adhesive is prepared according to the optimal formula of the orthogonal experiment, and its curing properties, the dynamic mechanic parameters, Fourier transform infrared spectrometer(FTIR) and the thermogravimetric analysis(TGA) are measured. And its shear adhesive strength is about 22.0MPa, its tensile strength is about 12.50MPa and its charpy impact strength is 9.41kJ/m2. The result of TGA and dynamic mechanic analysis(DMA) test have shown that the thermal stability of the epoxy adhesive is good before 335°C and its weight retention ratio is more than 90% and Tg≈50°C. By exploring the experiments, the tensile adhesive strength of the dumbbell sample in the concrete for the underwater curing epoxy adhesives is more than 2.26~2.98MPa. Epoxy resins have many excellent properties of mechanics and adhesion. By suitable modification of the epoxy resins, they have widely been applied for the leakage proofing in the underground and the submarine tunnel; the repairing and reinforcing of the dikes, dams and bridges; the repairing of the mechanical, electrical and chemical equipments[1]. Since1960’s, the underwater curing epoxy adhesives are developed and a great many works are done[2-10], for example, α-cyanoacrylate adhesive, the organosilicone adhesive, the urethane adhesive. But the open literatures abroad are few[11]. Zhang et al[12] investigated systematically the viscosity, reavtivity, mechanic and adhesive properties of the underwater curing epoxy adhesives for different curing agent systems, However, these studies concentrate on the laboratory results on the sheet steel piece, and the experimental testes on the damp and underwater concrete samples have not been seen up to now. This paper tried to explore the experiments on the damp and underwater concrete samples and obtained some good results based on the laboratory development on the sheet steel pieces.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

Tensile Properties of Low Nickel Austenitic Stainless Steel at Elevated Temperatures

2012 ◽  
Vol 159 ◽  
pp. 346-350
Author(s):  
Shu Min Liu ◽  
Jian Bin Zhang
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Elevated Temperatures ◽  
Peak Stress ◽  
Temperature Curve ◽  
Delta Ferrite ◽  
Cross Sectional ◽  
Different Temperatures ◽  
Increasing Temperature ◽  
Reduction Percentage

The elevated temperature short-time tensile test with the sample of casting low nickel stainless steel was conducted on SHIMADZU AG-10 at ten temperatures 300, 500, 600, 700, 800, 950, 1000, 1050, 1100, and 1250°C, respectively. The stress-strain curves with the thermal deformation at the different temperatures, the peak stress intensity-temperature curve, and the reduction percentage of cross sectional area-temperature curve were obtained. Metallographic test samples were prepared and the morphology of deforming zone was observed by optical microscopy. The experimental results show that the tensile strength of the test samples decreases with increasing temperature. From 300 to 800°C, the work harding occurred and the tensile strength increases with increasing strain. The work softening occurred and the tensile strength decreases with increasing strain at temperatures of 800 to 1250°C. The minimum value of reduction percentage was measured at 800 °C. The austenite and delta-ferrite are the main phase in the tested samples. When the tensile temperatures are increased to 1200°C, the delta-ferrite became thinner and broke down to be spheroidized.

A Brief Overview on High Temperature Friction and Wear

2010 ◽  
Author(s):  
Mustafa Bulut Coskun ◽  
Mahmut Faruk Aksit
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Friction And Wear ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Wear Performance ◽  
Large Pressure ◽  
Higher Power ◽  
Vibratory Motion ◽  
Increasing Temperature

With the race for higher power and efficiency new gas turbines operate at ever increasing pressures and temperatures. Increased compression ratios and firing temperatures require many engine parts to survive extended service hours under large pressure loads and thermal distortions while sustaining relative vibratory motion. On the other hand, wear at elevated temperatures limits part life. Combined with rapid oxidation for most materials wear resistance reduces rapidly with increasing temperature. In order to achieve improved wear performance at elevated temperatures better understanding of combined wear and oxidation behavior of high temperature super alloys and coatings needed. In an attempt to aid designers for high temperature applications, this work provides a quick reference for the high temperature friction and wear research available in open literature. High temperature friction and wear data have been collected, grouped and summarized in tables.

The High Temperature Deformation Behavior of A Cr2Nb Ordered Intermetallic System

1990 ◽  
Vol 213 ◽  
Author(s):  
G. E. Vignoul ◽  
J.M. Sanchez ◽  
J. K. Tien
Keyword(s):  
Deformation Behavior ◽  
Elevated Temperatures ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Law ◽  
Ordered Intermetallic ◽  
Intermetallic System ◽  
Increasing Temperature ◽  
Stress Term

ABSTRACTA basic characterization of the deformation behavior of Cr2Nb by microindention at ambient and elevated temperatures (up to 1400 °C) was undertaken. The microhardness of this system was seen to decrease with increasing temperature, from 1040 MPa at 25°C to 322 MPa at 1400 °C. Further, the microindention creep behavior of this system was studied by varying time on load at T = 1000 and 1200°C. Analysis of the data showed that m = 24 and Qapp = 477.61 kJ/mole. These unusually high values are indicative of the existence of an effective resisting stress against creep. When the data was fit against a microindention creep deformation law which was modified to incorporate an effective resisting stress term, it was determined that m = 4.5, Qcreep = 357 kJ/mole and the resisting stress term σr = 300 MPa.

scholarly journals Recyclable, Adhesive, Acetal-Linkage-Containing Epoxy Resins: Measuring the Adhesive Properties with Carbon Fibers

2016 ◽  
Vol 73 (3) ◽  
pp. 244-251 ◽  
Author(s):  
Ayaka YAMAGUCHI ◽  
Tamotsu HASHIMOTO ◽  
Yoshinori KAKICHI ◽  
Michio URUSHISAKI ◽  
Toshikazu SAKAGUCHI
Keyword(s):  
Carbon Fibers ◽  
Epoxy Resins ◽  
Adhesive Properties

Experimental Investigation of Adhesive Bonding for Post‐installed Rebars into Concrete at High Temperatures

2019 ◽  
Author(s):  
Thanyawat Pothisiri ◽  
Pitcha Jongvivatsakul ◽  
Vanichapoom Nantavong
Keyword(s):  
Experimental Investigation ◽  
High Temperatures ◽  
Mechanical Behaviour ◽  
Epoxy Resins ◽  
Adhesive Bonding ◽  
Elevated Temperatures ◽  
Adhesive Bond ◽  
Steel Rebar ◽  
Pull Out ◽  
Embedment Length

<p>The use of post‐installed rebars into existing reinforced concrete structures bonded with epoxy resins was constantly increasing due to the advantage of equivalent or even higher bearing capacities at service temperature, compared with conventional cast‐in‐place rebars. Previous studies have examined the effects of different parameters on the mechanical properties of bonded post‐installed rebars at normal temperature. These studies showed that, for rebar diameter equal to 10 mm, the load bearing capacity increases linearly with the embedment length up to 75 mm. However, upon exposure to high temperatures, the glass transition of epoxy resins may occur and affect the mechanical behaviour of the adhesive bond. Studying the mechanical behaviour of an adhesive anchor at high temperatures is therefore necessary. An experimental investigation is conducted herein to examine the characteristics of the adhesive bonding stress between steel rebar and concrete interface at elevated temperatures using a series of pull‐out tests with varying rebar diameters and embedment lengths.</p>

scholarly journals Effect of Cutting Temperature on Bending Properties of Carbon Fibre Reinforced Plastics

2019 ◽  
Vol 26 (1) ◽  
pp. 394-401 ◽  
Author(s):  
Ben Wang ◽  
Bowen Yang ◽  
Minghai Wang ◽  
Yaohui Zheng ◽  
Xianjun Hong ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Carbon Fibre ◽  
Cutting Temperature ◽  
Bending Stress ◽  
Bending Properties ◽  
Reinforced Plastics ◽  
Increasing Temperature ◽  
Carbon Fibre Reinforced Plastics

AbstractHigh cutting temperatures are easily generated during the machining of carbon fibre reinforced plastics (CFRP) and can induce serious damage during machining such as delamination. The purpose of this paper is to study the influence of cutting temperature on the performance of CFRP after machining. CFRP specimens were heated to temperatures within the vicinity of cutting temperatures generated during machining, then air-cooled and their bending properties investigated. The results showed that temperature had significant influence on the bending stress of CFRP. With increasing temperature, bending stress decreased and was lowest when the temperature was close to the glass-transition temperature. It was concluded that the bending properties of CFRP could be seriously affected if the material temperature was close to the glass-transition temperature and maintained for a period. As a result, cutting temperature should be kept lower than the glass transition temperature during machining.

scholarly journals Tribological Analysis of Contacts Between Glass and Tungsten Carbide Near the Glass Transition Temperature

2020 ◽  
Vol 68 (4) ◽  
Author(s):  
Petr Chizhik ◽  
Marcel Friedrichs ◽  
Dirk Dietzel ◽  
André Schirmeisen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Tungsten Carbide ◽  
Elevated Temperatures ◽  
Surface Deformation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Precision Glass Molding ◽  
Tribological Analysis

Abstract In recent years, the tribological contact between hard solids and glass at high temperatures has been identified as a crucial aspect in emerging technical applications like e.g., precision glass molding. To optimize such tribological systems, especially, the internal transformations of the glasses need to be considered, since these can determine which kind of energy dissipation channels become relevant, when the temperature of a glass is increasing and approaching the glass transition temperature. Here, we now introduce a new tribometer specifically developed for the analysis of glasses at elevated temperatures. Using this tribometer, we characterize friction of contacts between tungsten carbide (WC) and soda lime glass as a function of temperature, while additionally PMMA was analyzed for comparison. Our experiments reveal different tribological regimes where either simple sliding, surface fracturing, or surface deformation can be identified as relevant interface processes for the tribological behavior. Graphical Abstract

scholarly journals The Effects of Temperature on the Leaching Behavior of Cement Waste Forms - The Cement/Sodium Sulfate System

1989 ◽  
Vol 176 ◽  
Author(s):  
Mark Fuhrmann ◽  
Richard Pietrzak ◽  
John Heiser ◽  
Eena-Mai Franz ◽  
Peter Colombo
Keyword(s):  
Sodium Sulfate ◽  
Elevated Temperatures ◽  
Effective Diffusion ◽  
Finite Cylinder ◽  
Kcal Mole ◽  
Experimental Conditions ◽  
Waste Forms ◽  
Diffusion Controlled ◽  
Increasing Temperature ◽  
Relationship Of

ABSTRACTThe leaching mechanisms of simulated low-level radioactive waste forms are being determined as support for development of an accelerated leach test. Two approaches are being used: (1) comparison of leaching data with results of a model that describes diffusion from a finite cylinder, and (2) observation of the leaching process at temperatures between 20°C and 65°C. To provide results that can be used for modeling, leaching at elevated temperatures must change neither the leaching mechanism nor the structural controls of leaching such as the porosity. Releases of 137Cs, 85Sr, calcium, sodium and potassium from portland cement containing sodium sulfate, as a simulated evaporator sludge, have been determined under a variety of experimental conditions. Data from the leach tests were compared to model results for diffusion from the finite cylinder. While most leaching appears to be diffusion controlled, notable exceptions occur. For all samples, activation energies ranging between 6 and 11 Kcal/mole have been calculated from the relationship of the effective diffusion coefficient to increasing temperature, close to the expected value of 5 Kcal/mole for diffusion.

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