Effect of ageing process on mechanical properties of adhesive tubular butt joints in aqueous environment

Frigione

2020

Self Cite

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: Introductionmentioning

confidence: 99%

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

Frigione

2020

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“…The triethylenetetramine (TECZA, Z-1 trade name) is used for curing reactive resins [ 19 ]. The chemical formula of the triethylenetetramine curing agent is C 6 H 18 N 4 , and the structural formula is shown in Figure 1 .…”

Section: Methodsmentioning

confidence: 99%

“…This issue is considered in many publications [ 13 , 14 , 15 , 16 , 17 , 18 ]. Several of the author’s works also deal with the issue of aging various epoxy compounds in various environments [ 19 , 20 , 21 , 22 ], including acid [ 23 ] and also salt [ 24 ] environments. Based on obtained results by Rudawska and Brunella [ 25 ], it has been found that too high iron sulfate content in water has a negative effect on the selected mechanical properties of epoxy adhesive compound.…”

Section: Introductionmentioning

confidence: 99%

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

2021

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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.

“…Based on the obtained results, it has been found that too high an iron sulfate content in water has a negative effect on the selected mechanical properties of the epoxy compound. In other works by Rudawska et al [ 34 ], Rudawska [ 35 ], and Miturska et al [ 36 ], the seasoning time was also one of the factors analyzed during the aging research. It can be noticed that both the temperature and time of seasoning have an impact on the mechanical properties of the epoxy compounds.…”

Section: Introductionmentioning

confidence: 99%

The Impact of the Acidic Environment on the Mechanical Properties of Epoxy Compounds in Different Conditions

2020

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The aim of this work was to determine the impact of the acidic environment on the mechanical properties of two epoxy compounds in different conditions. The samples were made from the epoxy compounds composed of the epoxy resin (based on Bisphenol A), triethylenetetramine curing agent (unmodified compound), and calcium carbonate (CaCO3) (modified compound). The epoxy compound samples were seasoned for the following period of time (i.e., one week, one month, and three months). The environment was tap water and the acidic environment had three different concentrations of acetic acid (3%, 6%, and 9%). Strength tests of the epoxy compound samples were carried out in accordance with the ISO 604 standard. In the case of the modified composition, it is noted that the samples immersed in tap water were characterized by a higher strength than in acidic environments. A similar tendency was observed for unmodified compositions, although the differences were smaller than for the modified compositions. It was also noticed that the increase in the pH of the acidic solution in many analyzed cases contributed to the decrease in mechanical properties, although the immersion time in the acidic solution is important.