Evaluation of in-situ shrinkage and expansion properties of polymer composite materials for adhesive anchor systems by a novel approach based on digital image correlation

Singer, Gerald; Sinn, Gerhard; Lichtenegger, Helga C.; Veigel, Stefan; Zecchini, Michele; Wan‐Wendner, Roman

doi:10.1016/j.polymertesting.2019.106035

Cited by 29 publications

(14 citation statements)

References 22 publications

(25 reference statements)

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“…We foresee that it is near this temperature that the reconfigurability and self-healing properties of these materials can be conveniently taken advantage of at experimentally relevant time scales (∼10 2 s) . For example, previous research has reported T v values between 55 and 150 °C lower than the experimental temperatures required for patterning, healing, , or reprocessing. ,, The slope of the tangent for the low-temperature linear regime in all samples equals 23 × 10 –5 °C –1 , which corresponds to the coefficient of thermal expansion (α) for epoxy systems above the T g . , Meanwhile, the slope of the tangent in the high-temperature linear regime corresponds to ε 0 β –1 τ D –1 , where ε 0 is elastic strain (≈3% in all tests) and β is the heating rate, indicating the vitrimer is behaving as a Maxwell fluid at high temperatures. This observation is consistent regardless of sample composition or experimental parameters, as seen in Figure S6.…”

Section: Resultsmentioning

confidence: 83%

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Vitrimer Transition Temperature Identification: Coupling Various Thermomechanical Methodologies

Hubbard

Ren

Konkolewicz

et al. 2021

ACS Appl. Polym. Mater.

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Vitrimers hold great promise as adaptive materials capable of shape reconfigurability, welding, and self-healing due to dynamic covalent reactions occurring above the vitrimer transition temperature (T v ). Previous literature reports the T v as one value influenced mainly by chemistry; however, literature also reports significant inconsistencies when measuring or identifying T v trends. Herein, we present unique data interpretation methods to analyze stress−relaxation and elongational creep results allowing for excellent agreement between multiple T v measurement methodologies. We also demonstrate that experimental parameters (e.g., heating rate and applied axial force) and catalyst concentration are crucial in dictating the T v range. Varying the catalyst concentration or sample heating rate shifts the T v up to 115 and 43 °C, respectively. Additionally, we present a kinetic model confirming the temperature dependence of the transesterification rate-limiting step, exhibiting excellent agreement with experimental data. Fundamentally understanding the T v will inform future design of vitrimers toward applications ranging from recyclable actuators to structural adhesives.

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Section: Resultsmentioning

confidence: 83%

“…14,15,17 The slope of the tangent for the low-temperature linear regime in all samples equals 23 × 10 −5 °C−1 , which corresponds to the coefficient of thermal expansion (α) for epoxy systems above the T g . 41,42 Meanwhile, the slope of the tangent in the hightemperature linear regime corresponds to…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Vitrimer Transition Temperature Identification: Coupling Various Thermomechanical Methodologies

Hubbard

Ren

Konkolewicz

et al. 2021

ACS Appl. Polym. Mater.

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“…In this comprehensive experimental program two adhesives, representative for the construction market, were used for the anchor tests but also fully characterized as materials. [46], showing the substantial changes of properties in course of time while the curing related volume changes are reported in [47].…”

Section: Adhesive Propertiesmentioning

confidence: 91%

Consistent Time-to-Failure Tests and Analyses of Adhesive Anchor Systems

et al. 2020

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Motivated by tunnel accidents in the recent past several investigations into the sustained load behavior of adhesive anchors have been initiated. Nevertheless, the reliable life-time prediction of bonded anchor systems based on a relatively short period of testing still represents an unsolved challenge due to the complex non-liner viscoelastic behaviour of concrete and adhesives alike. This contribution summarizes the results of a comprehensive experimental investigation and systematically carried out time-to-failure analysis performed on bonded anchors under sustained tensile load. Two different adhesive materials that find widespread application in the building industry were used, one epoxy and one vinylester based. Performed experiments include full material characterizations of concrete and the adhesives, bonded anchor pull-out tests at different loading rates, and time-to-failure sustained load tests. All anchor tests are performed in a confined configuration with close support. After a thorough review of available experimental data and analysis methods in the literature the experimental data is presented with the main goals to (i) derive a set of recommendations for efficient time to failure tests, and (ii) to provide guidance for the analysis of load versus time-to-failure test data. Finally, a new approach based on a sigmoid function is proposed and compared to the established regression models. The analyses indicate a better agreement with the physics of the problem and, thus, more reliable extrapolations.

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“…As curing is irreversible, in daily use, the degree of cure fails to alter such that the change of material properties may be justified by degradation but not post-curing. In the case of building materials like concrete [5] with fastening in the structural engineering, the fastening is attached mechanically or by using adhesion regarding a thermosetting polymer [6][7][8][9][10]. The hardening process continues in the ambient temperature at a lower temperature than foreseen for the maximum stiffness [11].…”

Section: Introductionmentioning

confidence: 99%

Cure Kinetics and Inverse Analysis of Epoxy-Amine Based Adhesive Used for Fastening Systems

et al. 2021

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Thermosetting polymers are used in building materials, for example adhesives in fastening systems. They harden in environmental conditions with a daily temperature depending on the season and location. This curing process takes hours or even days effected by the relatively low ambient temperature necessary for a fast and complete curing. As material properties depend on the degree of cure, its accurate estimation is of paramount interest and the main objective in this work. Thus, we develop an approach for modeling the curing process for epoxy based thermosetting polymers. Specifically, we perform experiments and demonstrate an inverse analysis for determining parameters in the curing model. By using calorimetry measurements and implementing an inverse analysis algorithm by using open-source packages, we obtain 10 material parameters describing the curing process. We present the methodology for two commercial, epoxy based products, where a statistical analysis provides independence of material parameters leading to the conclusion that the material equation is adequately describing the material response.

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Evaluation of in-situ shrinkage and expansion properties of polymer composite materials for adhesive anchor systems by a novel approach based on digital image correlation

Cited by 29 publications

References 22 publications

Vitrimer Transition Temperature Identification: Coupling Various Thermomechanical Methodologies

Vitrimer Transition Temperature Identification: Coupling Various Thermomechanical Methodologies

Consistent Time-to-Failure Tests and Analyses of Adhesive Anchor Systems

Cure Kinetics and Inverse Analysis of Epoxy-Amine Based Adhesive Used for Fastening Systems

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