Laminated safety glass enables the safe construction of transparent structures. The mechanical behaviour depends on the polymeric interlayer both in the intact and in the post fracture state. In the present work, the mechanical behaviour of ethylene vinyl acetate-based (EVA) and ionoplastic interlayers is investigated for the intact laminated safety glass condition. In particular, the influence of the semi-crystalline structure on the stiffness behaviour is studied with X-Ray Diffraction, Differential Scanning Calorimetry and Dynamic-Mechanical-Thermal-Analysis. The studies on the mechanical behaviour of the interlayer in the fractured laminated safety glass were carried out with polyvinyl butyral-based (PVB) interlayers. First, the temperature and frequency (time) dependent linearity limits are determined in Dynamic-Mechanical-Thermal-Analyses, second, the nonlinear viscoelastic material behaviour is investigated with tensile relaxation tests at different temperatures and strain levels.
Author(s): Miriam Schuster
Series: Mechanik, Werkstoffe und Konstruktion im Bauwesen, 66
Publisher: Springer Vieweg
Year: 2022
Language: English
Pages: 355
City: Wiesbaden
Danksagung
Abstract
Zusammenfassung
Résumé
Contents
Glossaries
Abbreviations
Symbols
1 Introduction
1.1 Motivation
1.2 State of the art and state of research
1.2.1 Load bearing behaviour of intact laminated safety glass
1.2.2 Load bearing behaviour of fractured laminated safety glass
1.3 Objectives
1.4 Outline
2 Theoretical background
2.1 Polymers
2.1.1 Molecular and intermolecular structures
2.1.2 Classification based on thermo-mechanical behaviour
2.1.3 Thermodynamics and kinetics
2.1.4 Thermal transitions and relaxations in polymers
2.1.5 Laminated glass interlayers
2.2 Crystallization
2.2.1 Crystallization from the melt
2.2.2 Degree of crystallization
2.2.3 Morphology
2.2.4 Crystallization kinetics
2.2.4.1 Fundamentals about isothermal kinetic models
2.2.4.2 Fundamentals about non-isothermal kinetic models
2.2.4.3 Fundamental single step kinetics
2.2.4.4 Activation energy
2.2.4.5 Kinetic model functions
2.3 Viscoelasticity
2.3.1 Linear viscoelasticity - generalized Maxwell model
2.3.2 Linearity limits
2.3.3 Nonlinear viscoelasticity - Schapery model
2.4 Time-superposition principles
2.4.1 Time-temperature-superposition
2.4.2 Time-crystallinity-superposition
2.4.3 Time-stress / strain-superposition
3 General description of the experimental methods
3.1 Overview of tested materials
3.2 Differential Scanning Calorimetry
3.2.1 Functionality
3.2.2 Test set-up
3.2.3 Interpretation of the results
3.3 Dynamic-Mechanical-Thermal-Analysis
3.3.1 Different sweeps
3.3.2 Test set-up
3.3.3 Interpretation of the results
3.4 X-Ray Diffraction
3.4.1 Functionality
3.4.2 Test set-up
3.4.3 Interpretation of the results
3.5 Relaxation tests in uniaxial tensile mode
3.5.1 Functionality
3.5.2 Test set-up
3.5.3 Interpretation of the results
3.6 Overview of the performed tests
4 Investigation of the semicrystalline structure of EVA and ionoplastic interlayers
4.1 Crystalline regions and initial crystallinity
4.1.1 Differential Scanning Calorimetry
4.1.2 X-Ray Diffraction
4.2 Characteristic temperatures, melting and fusion enthalpies, and crystallinities
4.2.1 Differential Scanning Calorimetry
4.2.2 DMTA - temperature sweeps
4.3 Crystallization kinetics
4.4 Influence of physical aging
4.4.1 Differential Scanning Calorimetry and DMTA - temperature sweeps
4.4.2 DMTA - time sweeps
4.5 Summary and comparison with literature
5 Identification of time-superposition principles for EVA and ionoplastic interlayers
5.1 Temperature-frequency and frequency-temperature sweeps
5.1.1 Frequency- and temperature-dependent material behaviour
5.1.2 Comparison with temperature-sweep data
5.2 Creation of mastercurves
5.2.1 Mastercurves for SG
5.2.2 Mastercurves for cEVA
5.3 Decomposition of the horizontal shift factor
5.3.1 Time-superposition principles for SG
5.3.2 Time-superposition principles for cEVA
5.4 Determination of Prony series
5.5 Summary and comparison with literature
6 Determination of the linear viscoelastic behaviour and linearity limits for PVB
6.1 Linear viscoelastic material behaviour
6.1.1 Temperature-frequency sweeps
6.1.2 Glass transition temperatures
6.1.3 Mastercurves and Prony parameters
6.2 Linearity limits
6.3 Comparison of two different PVBs
6.4 Summary and comparison with literature
7 Characterization of the nonlinear viscoelastic behaviour of PVB
7.1 Uniaxial tensile relaxation tests
7.2 Comparison with Prony series
7.3 Introduction of the nonlinearity degree
7.4 Determination of Schapery model parameters
7.5 Summary and outlook
8 Application to engineering practice
8.1 Linear viscoelastic material parameters and glass design
8.1.1 Material type 1: amorphous polymers
8.1.2 Material type 2: semicrystalline polymers
8.1.3 Material type 3: chemically crosslinked polymers
8.1.4 Material type 4: unknown thermo-mechanical behaviour
8.2 Nonlinear viscoelastic material behaviour
8.3 Laminated glass design examples
8.3.1 Linear viscoelastic behaviour of semicrystalline interlayers
8.3.2 Linearity limit in intact laminated glass
9 Summary and outlook
Bibliography
Appendix
Appendix A Additional data
A.1 Laminated safety glass design with Wölfel’s sandwich theory
A.2 Semicrystalline structure
A.2.1 DSC and XRD test settings
A.2.2 Crystallization kinetics with DMTA
A.2.3 Relative crystallinities
A.2.4 DSC and XRD results for standard PVB
A.3 Linear viscoelastic behaviour of SG and cEVA
A.3.1 Test settings
A.3.2 Mastercurves, control plots and shift factors: SG
A.3.3 Mastercurves, control plots and shift factors: cEVA
A.3.4 Prony series
A.3.5 Verification of Prony parameter fits
A.4 Linearity limits of PVB
A.4.1 DMTA-TFS test settings
A.4.2 Mastercurves, control plots and shift factors for standard and structural PVB
A.4.3 Prony series for standard and structural PVB
A.4.4 DMTA-AS test settings
A.4.5 Linearity limits
A.4.6 Results for acoustic PVB
A.5 Nonlinear viscoelastic behaviour of PVB
A.5.1 Uniaxial tensile relaxation test settings
A.5.2 Stress, strain and Poisson’s ratio for standard and structural PVB
A.5.3 Degree of nonlinearity at T = 0°C
A.5.4 Preliminary uniaxial relaxation tests at small to medium strain levels and 0°C
A.5.5 Results for acoustic PVB
A.6 FEM model validation and mesh study
Appendix B List of publications, presentations and workshops
