Characterizing the toughness of an epoxy resin after wet aging using compact tension specimens with non-uniform moisture content

Published on Nov 1, 2014in Polymer Degradation and Stability5.03
路 DOI :10.1016/J.POLYMDEGRADSTAB.2014.08.005
Gustavo Quino5
Estimated H-index: 5
(KAUST: King Abdullah University of Science and Technology),
Jalal El Yagoubi4
Estimated H-index: 4
(KAUST: King Abdullah University of Science and Technology),
Gilles Lubineau42
Estimated H-index: 42
(KAUST: King Abdullah University of Science and Technology)
Sources
Abstract
Abstract Characterizing the change in toughness of polymers subjected to wet aging is challenging because of the heterogeneity of the testing samples. Indeed, as wet aging is guided by a diffusion/reaction process, compact tension samples (defined by the ASTM D5045 standard), which are relevant for toughness characterization but are somewhat thick, display a non-uniform moisture content over the bulk material. We define here a rigorous procedure to extract meaningful data from such tests. Our results showed that the relation between the moisture uptake of the whole sample and the measured toughness was not a meaningful material property. In fact, we found that the measured toughness depended on the locally varying moisture uptake over the cracking path. Here, we propose a post-processing technique that relies on a validated reaction/diffusion model to predict the three-dimensional moisture state of the epoxy. This makes identification of the variation in toughness with respect to the local moisture content possible. In addition, we analyze the fracture surface using micrography and roughness measurements. The observed variations in toughness are correlated with the roughness in the vicinity of the crack tip.
馃摉 Papers frequently viewed together
20124.43Polymer
19994.43Polymer
References18
Newest
#1Jalal El YagoubiH-Index: 4
#2Gilles Lubineau (KAUST: King Abdullah University of Science and Technology)H-Index: 42
Last. Abe AskariH-Index: 4
view all 5 authors...
In this paper, we study the hygrothermal aging of an anhydride-cured epoxy under temperature and hygrometry conditions simulating those experienced by an aircraft in wet tropical or subtropical regions. Gravimetric and dimensional measurements were performed and they indicate that there are three stages in this aging process: the rst one, corresponding to the early cycles can be called the \induction stage". The second stage of about 1000 cycles duration, could be named the the \swelling stage",...
Source
#1Jalal El Yagoubi (KAUST: King Abdullah University of Science and Technology)H-Index: 4
#2Gilles Lubineau (KAUST: King Abdullah University of Science and Technology)H-Index: 42
Last. Jacques Verdu (Arts et M茅tiers ParisTech)H-Index: 55
view all 4 authors...
Abstract Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of wate...
Source
#1M. Lai (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 5
#2John Botsis (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 38
Last. Dragan Coric (EPFL: 脡cole Polytechnique F茅d茅rale de Lausanne)H-Index: 5
view all 4 authors...
It is well known that moisture absorption impairs the mechanical and physical properties of polymers. Conventionally, the material's hygric strains are described as the product of a constant coefficient of moisture expansion (CME) and moisture concentration. This hypothesis, however, has not been thoroughly examined experimentally. In this paper, the hygro-mechanical response of a DGBA based epoxy is reported as a function of moisture uptake. Cylindrical specimens are made of epoxy with an axial...
Source
#1Gregory M. Odegard (MTU: Michigan Technological University)H-Index: 37
#2Ananyo Bandyopadhyay (MTU: Michigan Technological University)H-Index: 7
Exposure to extended periods of sub-Tg temperatures causes physical changes in the molecular structure of epoxy resins and epoxy-based materials to occur. These physical aging mechanisms include the reduction in free volume and changes to the molecular configuration. As a result, mechanical, thermodynamical, and physical properties are affected in ways that can compromise the reliability of epoxy-based engineering components and structures. In this review, the physical changes in the molecular s...
Source
#1Sabina Alessi (University of Palermo)H-Index: 15
#2Daniel Gheorghe Conduruta (University of Palermo)H-Index: 2
Last. Giuseppe Spadaro (University of Palermo)H-Index: 23
view all 5 authors...
Abstract A model epoxy resin/anhydride system, modified with a polyethersulfone (PES) engineering thermoplastic toughening agent, has been studied under hydrothermal ageing in order to investigate the modification of the thermal, morphological and mechanical behaviour through dynamical mechanical thermal analysis, SEM microscopy and fracture toughness test respectively. Two different concentrations of the toughening agent were used in the blends and two ageing conditions have been considered, co...
Source
#1Sabina Alessi (University of Palermo)H-Index: 15
#2Daniel Gheorghe Conduruta (University of Palermo)H-Index: 2
Last. Giuseppe Spadaro (University of Palermo)H-Index: 23
view all 5 authors...
Abstract The hydrothermal ageing of epoxy鈥搕hermoplastic blends, used as matrices for carbon fibre composites, cured by electron beam, has been studied. Two different thermoplastic percentages have been adopted. A聽suitable choice of both curing process and formulation parameters allows to carry out irradiation at mild temperature with several advantages, coming from a 鈥渘on thermal鈥 process, for both the final properties of聽the materials and the environment. Nevertheless the occurring of vitrifica...
Source
#1Celine Chaleat (UQ: University of Queensland)H-Index: 8
#2Peter J. Halley (UQ: University of Queensland)H-Index: 56
Last. Rowan W. Truss (UQ: University of Queensland)H-Index: 25
view all 3 authors...
The effect of moisture content on tensile and fracture properties of a plasticised starch/high molecular weight polyol blend was investigated. A wide range of mechanical behaviour was achieved by varying slightly the water uptake of this material. At low moisture content, the Young's modulus was 3800 MPa and the yield stress, 54 MPa. When the moisture content reached 15 wt%, their values dropped, respectively, to around 1500 MPa and 21 MPa. As the material behaviour varies greatly over the moist...
Source
#1Tam谩s B谩r谩ny (BME: Budapest University of Technology and Economics)H-Index: 23
#2Eniko Foldes (BME: Budapest University of Technology and Economics)H-Index: 6
Last. Tibor Czig谩ny (BME: Budapest University of Technology and Economics)H-Index: 34
view all 3 authors...
The in-plane (plane stress) fracture toughness of two polyester (PET, PETG) sheets were assessed using the essential work of fracture (EWF) method after thermal and hygrothermal aging performed just below glass temperature. This ensured that physical aging takes place. On the aged sheets the yield stress (蟽y), enthalpy relaxation (螖H) and EWF parameters were determined. It was observed that the essential work of fracture component related to the specific yielding (we,y) is suitable for assessing...
Source
#1Yong-Cheng Lin (TJU: Tianjin University)H-Index: 65
#2Xu Chen (TJU: Tianjin University)H-Index: 46
Abstract Epoxy resins are attractive materials for many engineering applications, as they are low in density, have excellent mechanical properties and are easily fabricated by processes such as injection molding, extrusion and vacuum forming. However, the hostile humid environment can degrade the epoxy system because most epoxies absorb moisture. In this paper, the tensile fracture surfaces have been analyzed by a scanning electron microscopy (SEM) for the initial dry, moisture-saturated (precon...
Source
#1Yong-Cheng Lin (TJU: Tianjin University)H-Index: 65
#2Xu Chen (TJU: Tianjin University)H-Index: 46
Thermosetting epoxy resins are attractive materials for many engineering applications, as they are low in density, with excellent mechanical properties and easily fabricated by processes such as injection molding, extrusion and vacuum forming. However, the hostile hygrothermal environment can degrade the epoxy system. In this study, moisture sorption鈥揹esorption鈥搑esorption characteristics of the DGEBA/DDA epoxy system have been investigated by the hygrothermal aging and molecular dynamic (MD) sim...
Source
Cited By23
Newest
Source
#1Kepa ZuluetaH-Index: 3
#2Aizeti BurgoaH-Index: 3
Last. I帽aki Martinez (Agency for Science, Technology and Research)H-Index: 2
view all 3 authors...
Source
#1Gustavo Quino (University of Oxford)H-Index: 5
#2Antonio Pellegrino (University of Oxford)H-Index: 9
Last. Nik Petrinic (University of Oxford)H-Index: 23
view all 3 authors...
Multifunctionality, lightweight and resistance to corrosion are some of the several advantages that fibre composites display with respect to other materials across a wide range of applications. In aerospace and marine industry, however, we can encounter challenges arising from certain working conditions that can significantly affect the mechanical response and integrity of composite structures. First, humidity or water exposure can induce reduction of the material strength and stiffness. Second,...
Source
Source
Abstract This study reports on the effects of water absorption on the anisotropic mechanical response of an epoxy resin reinforced with E-glass fibres. Composite specimens were conditioned by immersion in pure water at 50鈥癈 for different time durations, up to full saturation. Water-saturation resulted in reduction of stiffness and strength, in the range of strain rate 0.001鈥700s鈭1. Experiments on re-dried specimens after water saturation showed only a small recoverability of the original mechan...
Source
#1Mirenia Kalina Teixeira de Brito (UFCG: Federal University of Campina Grande)H-Index: 2
#2Wanessa Raphaella Gomes dos Santos (UFCG: Federal University of Campina Grande)H-Index: 2
Last. Antonio Gilson Barbosa de Lima (UFCG: Federal University of Campina Grande)H-Index: 14
view all 7 authors...
This work aims to study numerically the moisture absorption in polymer composite reinforced with vegetable fibers using the Langmuir model which considers the existence of free and entrapped water molecules inside the material. A three-dimensional and transient modeling for describing the water absorption process inside the composite and its numerical solution via finite volume method were presented and discussed. Application has been made for polymer composites reinforced with sisal fiber. Emph...
Source
#1S. SwainH-Index: 1
#2S. BeuraH-Index: 3
Last. U. K. Mohanty (NITR: National Institute of Technology, Rourkela)H-Index: 6
view all 5 authors...
Abstract Twelve ply glass fibre-reinforced plastic (GFRP) composite samples, hung in the open for out-doors ageing, were characterised in terms of moisture intake, inter laminar shear stress (ILSS) (using 3-point bend test) and glass transition temperature (Tg) (using low temperature differential scanning calorimetry; DSC) as a consequence of the exposure to out-doors. The local relative humidity and the temperature fluctuations were recorded. The responses so obtained were compared with those p...
Source
#1Gustavo Quino (University of Oxford)H-Index: 5
#2Antonio Pellegrino (University of Oxford)H-Index: 9
Last. Nik Petrinic (University of Oxford)H-Index: 12
view all 4 authors...
Abstract The study reports the measured effects of water absorption on an epoxy resin. Epoxy samples were exposed to wet conditioning environments including pure water, NaCl-water solution, and pure water at boiling temperature, measuring absorption as a function of time. Vickers hardness and indentation creep tests were performed and the mechanical response of the material to uniaxial stress was also measured in both compression and tension, at imposed strain rates in the range 0.001鈥2500 s鈭1. ...
Source
#1Jos茅 Gonilha (IST: Instituto Superior T茅cnico)H-Index: 12
#2Jo茫o R. Correia (IST: Instituto Superior T茅cnico)H-Index: 36
Last. Jos茅 Sena-Cruz (University of Minho)H-Index: 23
view all 4 authors...
Abstract In order to overcome the main mechanical drawbacks of GFRP profiles, namely their high deformability and proneness to instability phenomena, several GFRP-concrete hybrid solutions comprising bonded connections with epoxy adhesive have been proposed. Although being able to provide almost full interaction at the GFRP-concrete interface(s) (at least in the short-term), there is very little information about the durability of such connection systems, which raises concerns about the long-ter...
Source
#1Giuseppe Pitarresi (University of Palermo)H-Index: 19
#2Andrea Toscano (University of Palermo)H-Index: 5
Last. Sabina Alessi (University of Palermo)H-Index: 15
view all 3 authors...
Abstract The effects of water uptake on the fracture toughness of epoxy systems with high glass-transition temperatures (Tg above 170鈥癈) are investigated. Aging conditioning has been conducted in hot water, followed by a desorption conditioning in a room temperature dry-airborne. Water aging determines plasticisation effects and crosslink-density modifications, revealed by reductions of the Tg. It is less known how such modifications influence the material fracture toughness. In this study, Sin...
Source
This website uses cookies.
We use cookies to improve your online experience. By continuing to use our website we assume you agree to the placement of these cookies.
To learn more, you can find in our Privacy Policy.