The Effect of Ageing in Water Solution Containing Iron Sulfate on the Mechanical Properties of Epoxy Adhesives

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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: Introductionmentioning

confidence: 99%

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

Rudawska

Frigione

2020

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“…The curing agent is an amine curing agent (triethylenetetramine curing agent, Z-1 trade name, CIECH Resins, Nowa Sarzyna, Poland). The properties of the used epoxy resin and curing agent were presented in [ 33 , 36 ]. Strength parameters of the used epoxy resin with the addition of the triethylenetetramine curing agent after being cured for seven days at ambient temperature are presented in Table 2 .…”

Section: Methodsmentioning

confidence: 99%

“…Works dealing with the analysis of the degradation process of epoxy compositions in various aqueous environments have previously been published [ 19 , 21 , 24 , 27 , 28 , 29 , 30 , 31 , 32 ]. In the work by Rudawska and Brunella [ 33 ], the effect of operating factors such as seasoning in water solution, containing iron sulfate, and the time of seasoning was investigated. 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.…”

Section: Introductionmentioning

confidence: 99%

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

Rudawska

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.

“…Bending strength (MPa) 80-100 Compressive strength (MPa) 70-90 Shear strength of joint cured for 16 h at 20-25 • C, 6 h at 80 ± 2 • C (MPa), not lower than 7.84 Shear strength of joint cured for 7 days at 20-25 • C (MPa), not lower than 5.86 The selected physicochemical properties of Epidian 53 epoxy resin were presented in [6].…”

Section: Properties Valuementioning

confidence: 99%

“…In liquid form, they can be used for joining elements made of different materials. When subjected to curing, however, these materials form solid, resistant structures with low specific weight, which show different properties in various environments [5][6][7][8][9], including water [10][11][12][13], moisture [14][15][16], humid [17][18][19] or hydrothermal conditions [20].…”

Section: Introductionmentioning

confidence: 99%

The Effect of the Salt Water Aging on the Mechanical Properties of Epoxy Adhesives Compounds

Rudawska¹

2020

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The objective of this study is to compare the effect of selected operating factors on the mechanical properties of epoxy adhesive compounds aged in salt water. Five different water environments were tested: tap water, normal seawater (reference salinity value), seawater with double reference salinity value, seawater with half of the reference salinity and seawater with a quarter of the reference salinity value. Samples of two different adhesive compounds were prepared using the epoxy resin and triethylenetetramine curing agent. One of the compounds was filled with calcium carbonate. The samples were aged in five different water environments for three months, one month and one week, respectively. Mechanical properties of the cured adhesive compound samples were determined via strength tests performed on the Zwick/Roell Z150 testing machine in compliance with the EN ISO 604 standard. The objective of the experiments was to determine the effect of different seawater environments on selected mechanical properties (including strength) of the fabricated adhesive compounds.Polymers 2020, 12, 843 2 of 20 used as aging environments of DCB (Double Cantilever Beam) and ODCB (open-DCB) specimens. Bordes et al. [21] investigated the long-term behavior of adhesively bonded double lap shear steel joints aged in seawater and the degradation of mechanical properties of an epoxy adhesive. Aging on bulk adhesive was performed in deionized water, salt and seawater at three temperatures, 20, 40 and 60 • C. Heshmati et al. [15] investigated the effects of aging the epoxy adhesive and bonded joints (fiber-reinforced-polymer/steel joints) in five harsh environments, including salt water solution at various temperatures (20 • C and 45 • C). Three-dimensional (3D) moisture diffusion properties of different FRPs (fibre reinforced polymer/steel) and adhesive material in various aging conditions were characterized. In another work, Heshmati et al. [9] presented the effects of cyclic wet-dry, freeze-thaw and combined wet and freeze-thaw conditions (distilled water and salt water, when combined with freeze-thaw for 125 and 250 cycles) on the mechanical behavior of bonded FRP/steel joints. The results have shown, among other things, that the ductility of the adhesive is reduced after it has been dried from the wet state.The objective of this study is to compare the selected mechanical properties of cured adhesive compounds (unmodified and modified alike) aged in seawater environments with different salt concentrations. The experiments aim to determine and compare the compressive strength, compression modulus and compressive strains of the cured epoxy adhesives under study.Polymers 2020, 12, 843 4 of 20 filler were weighed (Table 3) and mixed. After that, the curing agent was added to the compound. The preparation process parameters for both modified and unmodified epoxy adhesive compounds were the same. Shape, Dimensions and Fabrication of the Adhesive Compound Samples