Investigation of selected properties of adhesive compositions based on epoxy resins

Frigione

2020

Polymers

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The purpose of this study was to assess the effects of different aqueous environments (i.e., demineralised, distilled and spring water) on the mechanical properties of a cold-cured bisphenolic epoxy resin modified with the addition of calcium carbonate filler, typically employed as structural adhesive. The parameters selected for the analysis have been; the kind of curing agent employed to cure the epoxy resin at ambient temperature (i.e., Mannich base and triethylenetetramine); the load of calcium carbonate added to liquid epoxy (i.e., from 1 to 3 g per 100 g of resin) and; the duration of the exposure to the different aging conditions (i.e., from 1 to 10 months). Cylindrical specimens of calcium carbonate-modified epoxy systems were tested in compression mode, before and after each of the aging regimes. The effect of the selected curing agents is very small, and they are both suitable for a cure at ambient temperature, on the unfilled epoxy on compressive maximum strength and strain at break; the choice of the hardener affects instead the compressive modulus. The CaCO3 amount was demonstrated to have a significant effect on the mechanical characteristics of un-aged epoxy systems, leading to growth in compressive modulus and maximum strength with reductions in strain at break. Generally speaking, the aging time noticeably affects the compressive properties of calcium carbonate-modified epoxies while almost negligible is the kind of water employed in each exposure regime. Notwithstanding the adverse effects of an aqueous environment on compressive mechanical properties of CaCO3-filled epoxies, these systems keep compressive modulus and maximum strength greater than, and close to, respectively, the same characteristics measured on unaged unfilled control epoxies, demonstrating the positive effect of the addition of this kind of filler to epoxy-based structural adhesives, especially with the addition of 2 and 3 g of CaCO3 per 100 g resin. The results obtained in this study demonstrated that it is possible to contrast the detrimental effects observed in cold-cured epoxy-based structural adhesives due to their aging in water upon the addition of limited amounts (particularly at 2 and 3 g per 100 g resin) of a cheap CaCO3 filler.

Section: Characteristic Propertiesmentioning

confidence: 99%

Aging Effects of Aqueous Environment on Mechanical Properties of Calcium Carbonate-Modified Epoxy Resin

Frigione

2020

Polymers

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“…The characteristics of the curing agents used in the tests are presented in [35]. The technology of preparing the adhesive compounds is described in [36]. After preparation, the adhesive compounds were applied on the joined surfaces (on one joined surface in particular joints) during so called 'compound's working life' .…”

Section: Surface Preparationmentioning

confidence: 99%

Comparison of the adhesive joints’ strength of the similar and dissimilar systems of metal alloy/polymer composite

2019

Appl Adhes Sci

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Bonding technology is one of the most popular methods of joining various constructional materials [1-3]. It plays a vital role in production of different types of machines and tools [2]. This fact results from numerous advantages of the adhesive joints. The most important ones include the capacity of joining construction materials of different physical and chemical properties [4-6], as well as of significantly different sizes (e.g. thickness) [4, 7-9]. A lot of advantages of the adhesive joints have contributed to the fact that they are widely used in aviation [8, 10-12], aeronautics [13] and automotive [14, 15]. One of the most important advantages is the ability to make dissimilar joints [5, 16-18]. He and Ge [4] tested the effect of similar versus dissimilar assembled adherends of adhesively bonded composite joints, on the dynamic strength of single-lap. Pinto et al. [16] investigated the tensile strength of single-lap joints between similar and dissimilar adherends (included polyethylene (PE), polypropylene (PP), carbon-epoxy (CFRP), and glass-polyester (GFRP) composites) bonded with an acrylic adhesive.

“… Okba et al [ 29 ] underline that the decrease of e.g., residual compressive strengths depends on the type of adhesive and also other factors e.g., elevated temperature level and to a lesser effect on the exposure time. The results presented in work [ 30 ] demonstrated that the tensile strength is influenced by both the type of resin and the type of the curing agent; in addition, their ratios in epoxy compounds have an impact on the tensile strength of the specimens in the cured state. The curing agent content has a significant effect on the properties of the epoxy compound even within the range of stoichiometric ratios.…”

Section: Discussionmentioning

confidence: 99%

Mechanical Properties of Epoxy Compounds Based on Bisphenol a Aged in Aqueous Environments

2021

Polymers

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(1) Background: The aim of the work is to determine the influence of selected aqueous environments of various types of liquids on the strength of adhesive compositions prepared from epoxy resin based on bisphenol A combined with two different curing agents: tritethylenetetramine and polyaminoamide C. (2) Methods: The cured epoxy adhesive compounds samples were seasoned in four aqueous environments of the liquid: rainwater, demineralized water, tap water, and a sweetened drink. Three variants of the aging time in the above-mentioned operating environments were adopted: one month, two months, and three months. After the specified maturing time, samples of epoxy adhesive compositions were subjected to the strength tests on the Zwick/Roell 150 testing machine, which is in accordance with ISO 604 standard, determining the compressive strength. (3) Results: On the basis of the obtained strength test results and their analysis, it was noticed, inter alia, that the strength of the epoxy compounds decreases with the aging time in all used aqueous environments. Moreover, in the case of both types of the epoxy compounds, the highest strength was achieved after aging in demineralized water.