Characterization of seawater and weather aged polyurethane elastomer for bend stiffeners

Oliveira, Geovanio Lima de; Gomez, Aynor J. Ariza; Caire, Marcelo; Vaz, Murilo Augusto; Costa, Marysilvia Ferreira da

doi:10.1016/j.polymertesting.2017.02.012

“…Structural adhesives have a long history in marine applications, playing a key role in the assembly of pleasure boats and racing craft [1]. The interactions between water and polymers have been studied by many authors, and effects are usually classified as either reversible (plasticization [2], swelling [3]) or irreversible (hydrolysis [4], oxidation). The influence of water on epoxy resins has received particular attention.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Mechanical Behaviour of a Bulk Epoxy Adhesive in a Marine Environment

Ilioni

¹

,

Gac

²

,

Bădulescu

³

et al. 2018

The Journal of Adhesion

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This article describes an approach to predict the behaviour of an epoxy adhesive in bulk form in a marine environment. First, the material, the experimental conditions and the predictive framework are described. Then the experimental results are presented, which indicate that the effects on yield stress of either a uniform water profile or elevated testing temperature can be shown to be equivalent when plotted versus T-Tg. Moreover, a discussion of these results shows how they can be used to predict changes in the mechanical properties of the adhesive. Prediction results for yield stress are in good agreement when they are compared with experimental results for the case of a water profile gradient, in order to evaluate the relevance and limitations of the model.

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“…e.g. [1][2][3][4][5][6][7][8][9]). In the literature, studies sometimes miss important details like chemical composition, morphology or glass transition of the examined PU (e.g.…”

mentioning

confidence: 99%

“…In the literature, studies sometimes miss important details like chemical composition, morphology or glass transition of the examined PU (e.g. [1,4,7,[9][10][11][12][13][14][15][16]). Other publications focus on chemical ageing effects but do not consider the consequences on macroscopic material properties (e.g.…”

mentioning

confidence: 99%

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Water in polyurethane networks: physical and chemical ageing effects and mechanical parameters

Possart

¹

,

Zimmer

²

2022

Continuum Mech. Thermodyn.

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The chemical structure, polymer mobility and mechanical properties are studied for a cross-linked amorphous poly(ether urethane) (PU) from glass transition to rubber elasticity for juvenile dry samples and for water-saturated states after exposure to humid air (r.h. = 29, 67, 95, 100%) at $$60~^\circ \hbox {C}$$ 60 ∘ C during 1 y of ageing. For saturated samples, network chain cleavage is the chemical ageing mechanism, but it is too weak and slow to affect on the physical properties significantly within 1 y. Water acts primarily in a physical manner. Within 1 d, $$\hbox {H}_{{2}}\hbox {O}$$ H 2 O molecules replace part of the weak urethane H-bonds by $$\hbox {H}_{{2}}\hbox {O}$$ H 2 O –urethane H-bonds and reduce all other physical interactions between network chains by solvating hydrophilic segments. Thus, the cooperative polymer mobility strongly amplifies: The gain of specific conformational entropy doubles across the caloric glass transition, which shifts by −17 K. A $$\hbox {H}_{{2}}\hbox {O}$$ H 2 O concentration of only $$\hbox {c}_{{\mathrm{H}_2\mathrm{O}}}~\approx ~(0.4~\ldots ~0.5)~\hbox {c}_{\mathrm{\mathrm{H}_2\mathrm{O},max}}$$ c H 2 O ≈ ( 0.4 … 0.5 ) c H 2 O , max suffices for the major part of these fast rearrangements. Some part of the water slowly forms (during 3–4 months) a finely dispersed water-rich mixed phase with the PU chains. Except the new phase, these molecular processes of physical ageing strongly affect the mechanical properties at damage-free deformation. For dry PU in the glass transition, the shear modulus, $$\mu _{\mathrm{relaxed}}$$ μ relaxed (T), after viscoelastic stress relaxation only depends on the deformation-induced entropy change—like in the rubber elastic state. Within one month, water drastically decreases the viscoelastic response, as expected for plasticisation. However, $$\mu _{\mathrm{relaxed}}$$ μ relaxed (T) slightly grows in wet PU. $$\hbox {H}_{{2}}\hbox {O}$$ H 2 O molecules cause these opposite trends by boosting the cooperative mobility (i.e. extension of the accessible conformational space and entropy by reduction in energy barriers) and by occupation of free volume compartments. Water quickly reduces the fracture parameters by about 50%. We explain that embrittlement by the $$\hbox {H}_{{2}}\hbox {O}$$ H 2 O -induced facilitation of cooperative network chain motions, which let fracture proceed with less energy. In summary, our findings provide a detailed conception of the molecular effects the $$\hbox {H}_{2}\hbox {O}$$ H 2 O molecules have on the PU network, and they explain the consequences for the mechanical properties.

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“…Both the mechanisms are plausible and could occur concurrently. Hydrolysis has been identified as one of the main mechanisms affecting the PU adhesive (Buchman et al, 1991; Davies and Evrard, 2007; Boubakri et al, 2009; Petrie, 2011; Gac et al, 2013; Zain et al, 2014; Weiss et al, 2016; de Oliveira et al, 2017; Sousa et al, 2018). However, these previous studies are difficult to compare due to the wide variety of PU adhesive formulations.…”

Section: Introductionmentioning

confidence: 99%

Durability of Polymer Metal Multilayer: Focus on the Adhesive Chemical Degradation

Dubelley

¹

,

Bas

²

,

Planès

³

et al. 2018

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Mechanical toughness and high barriers to air and water may be combined in a polymer–metal multilayer film, provided that the two materials are properly bonded together. Delamination is indeed the most severe flaw observed in service. This suggests that the polyurethane (PU) adhesive at the polymer–metal interface fails to bear the shear forces, as happens principally if a multilayer system is submitted to elevated temperature and humidity. A Raman microscopy of the multilayer revealed a cohesive delamination, with glue on both the surfaces. A detailed investigation of the kinetic of degradation of the polyester was therefore carried out. IR spectroscopy of the standalone PU film hydrolyzed in a controlled manner furnished a series of aging markers. The reference curve was established for approximately a year in continuous severe aging conditions. This curve could be further used to compare the amount of degradation in real systems in a wide range of conditions and time. Moreover, at the metallized interphase, a complex with a free hydroxyl group was detected. The content of this AlIII complex based on terephthalate or carbamate increases with the progress of the ester hydrolysis reactionin the layer.

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Characterization of seawater and weather aged polyurethane elastomer for bend stiffeners

Cited by 20 publications

References 26 publications

Prediction of Mechanical Behaviour of a Bulk Epoxy Adhesive in a Marine Environment

Prediction of Mechanical Behaviour of a Bulk Epoxy Adhesive in a Marine Environment

Water in polyurethane networks: physical and chemical ageing effects and mechanical parameters

Durability of Polymer Metal Multilayer: Focus on the Adhesive Chemical Degradation

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