4 research outputs found
Water Responsive Mechano-adaptive Elastomer Composites based on Active Filler Morphology
Get PDFMechanically adaptable elastomer composites are a class of stimuli responsive polymer composites which can reversibly change its mechanical properties when it comes in contact with stimuli like electric field, light, water, solvents, ions and others. Mechanically adaptable composites are mainly inspired from the sea cucumber dermis which has the ability to change the stiffness of its dermis rapidly and reversibly (connecting tissue) when it is immersed in water.
In this work, efforts have been made to develop mechano-adaptive elastomer composites using water as stimuli. In such a case, elastomer composite should absorb water significantly, in order to respond quickly to the stimuli. Therefore, as a first step, stable and repeatable water swellable elastomer composites have been developed by blending epichlorohydrin terpolymer (GECO) with an ethylene oxide based hydrophilic polymer resin (GEPO).
Two different approaches have been thereafter explored to develop mechano-adapative composites based on the developed water swellable elastomer composite. In the first approach, the solidâliquid phase transition of the absorbed water is used to tune mechanical properties around 0 °C. The solidified absorbed water (ice crystals) below 0 °C, acts as reinforcing filler, enhancing the mechanical properties (hard state). The ice crystals liquefy above 0 °C and plasticize the polymer chain, thereby reducing the mechanical properties (soft state). In the second approach, the polymorphic transition of calcium sulphate (CaSO4) in presence of water/heat have been exploited by dispersing it as filler in the developed water swellable elastomer composite. Mechanical adaptability is realized by the reinforcement caused when the composite is exposed to water treatment process. Further, this mechanical strength (reinforcement) can be brought back to its initial soft state (unreinforced state) by the heat treatment process. This reversible reinforcing and non-reinforcing ability of the calcium sulphate filler is attributed to the differences in polymerâfiller interaction, due to the in situ morphology transformation (micro to nano) of the filler particles.
This study reveals the possibility of utilizing conventional rubber technology in developing mechanically adaptable composites with an easily accessible stimulus like water. The two strategies explored here present huge opportunities in developing future smart materials.:Contents
1 Introduction 1
1.1 General introduction 1
1.2 Aim and motivation of the work 3
1.3 Scope of the work 5
2 Literature review 7
2.1 Mechanically adaptive polymer composites 7
2.1.1 Mechanical adaptability triggered by different stimuli 7
2.1.2 Water induced mechano-adaptive composites 10
2.1.3 Possible future applications of mechanically adaptive systems 14
2.2 Water absorption in elastomer composites 16
2.2.1 Strategies used for developing water swellable elastomer composites 17
2.2.2 States of water present in the polymers 20
2.2.3 Effect of water absorption on the thermal and mechanical properties 22
2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24
2.2.5 Application of water swellable elastomer composites 25
2.3 Calcium sulphate and its polymorphic transition 26
3 Experimental 30
3.1 Materials 30
3.1.1 Polymers 30
3.1.2 Fillers 31
3.2 Preparation of rubber composites 32
3.2.1 Compounding and mixing 32
3.2.2 Curing study and molding 34
3.3 Characterization 35
3.3.1 Water swelling studies 35
3.3.2 Thermal analysis (DSC and TGA) 36
3.3.3 Dynamic mechanical analysis (DMA) 36
3.3.4 Stressâstrain studies 37
3.3.5 Fourier transform infrared spectroscopy (FTIR) 38
3.3.6 Morphological analysis 39
3.3.7 X-ray diffraction (XRD) 40
3.3.8 Raman spectroscopy 40
4 Results and discussions 42
4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42
4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42
4.1.2 Water absorption behavior of GECO/GEPO blends 49
4.1.3 Effect of water swelling on thermal and mechanical properties 54
4.1.4 Cyclic water swellable characteristics 58
4.2 Thermo-responsive mechano-adaptable composites based on solidâliquid phase transition of absorbed water. 60
4.2.1 Quantitative analysis of in situ formed ice crystals 61
4.2.2 Characterization of the filler (ice crystals) morphology 64
4.2.3 Polymerâfiller interaction 68
4.2.4 Mechanical adaptability analysis 71
4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77
4.3.1 Process and conditions for mechanical adaptability 79
4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83
4.3.3 In situ morphology transformation analysis 86
4.3.4 Mechanical adaptability investigations 89
5 Conclusions and outlook 96
5.1 Conclusions 96
5.2 Outlooks 99
6 References 100
7 Appendix 109
8 Abbreviations 111
9 Symbols 114
10 Figures 117
11 Tables 123
12 Publications 124Mechanisch-adaptive Elastomer-Verbundwerkstoffe sind eine Klasse von stimuli-responsiven Polymer-Verbundwerkstoffen, welche ihre mechanischen Eigenschaften reversibel verÀndern können, wenn sie mit Stimuli, wie z.B. einem elektrischem Feld, Licht, Wasser, Lösungsmitteln oder Ionen angeregt werden. Mechanisch anpassbare Verbundwerkstoffe sind hauptsÀchlich von der Haut der Seegurke inspiriert, welche in der Lage ist, die Steifigkeit ihrer Dermis (Bindegewebe) beim Eintauchen in Wasser schnell und reversibel zu verÀndern.
Ziel dieser Arbeit war, mechanisch-adaptive Elastomer-Verbundwerkstoffe zu entwickeln, welche Wasser als Stimulus nutzen. FĂŒr diese Anwendung sollte das Elastomermaterial Wasser in einer signifikanten Menge aufnehmen können, um schnell auf den externen Reiz zu reagieren. Daher wurden in einem ersten Schritt stabile und reversibel wasserquellbare Elastomerblends hergestellt, indem ein Epichlorhydrin-Terpolymer (GECO) mit einem hydrophilen Polymerharz auf Ethylenoxidbasis (GEPO) verschnitten wurde.
In der Folge wurden zwei verschiedene AnsĂ€tze zur Entwicklung mechanisch-adaptiver Verbundwerkstoffe auf Basis des so entwickelten wasserquellbaren Elastomerkomposites verfolgt. Beim ersten Ansatz wird der Fest-FlĂŒssig-PhasenĂŒbergang des aufgenommenen Wassers genutzt, um die mechanischen Eigenschaften imâ Bereich von 0 °C einzustellen. Das erstarrte absorbierte Wasser (Eiskristalle) wirkt unter 0 °C als verstĂ€rkender FĂŒllstoff und verbessert die mechanischen Eigenschaften (harter Zustand). Die Eiskristalle verflĂŒssigen sich oberhalb von 0 °C und plastifizieren das Polymer, wodurch die mechanische VerstĂ€rkung wieder herabgesetzt wird (weicher Zustand). Im zweiten Ansatz wurde der polymorphe Ăbergang von Calciumsulfat (CaSO4) in Gegenwart von Wasser bzw. WĂ€rme genutzt, indem es als FĂŒllstoff in einem wasserquellbaren Elastomerkomposit dispergiert wurde. Die mechanische Adaptierbarkeit wird durch die mechanische VerstĂ€rkung erreicht, welche bei der Wasseraufnahme des Verbundwerkstoffes entsteht. AnschlieĂend kann diese mechanische Festigkeit (VerstĂ€rkung) durch eine WĂ€rmebehandlung wieder in ihren ursprĂŒnglichen weichen Zustand (unverstĂ€rkter Zustand) zurĂŒckgefĂŒhrt werden. Diese reversible Schaltbarkeit der VerstĂ€rkungswirkung des Calciumsulfat-FĂŒllstoffes wird auf die Unterschiede in der Polymer-FĂŒllstoff-Wechselwirkung aufgrund der Transformation der in situ-Morphologie (Mikro zu Nano) der FĂŒllstoffpartikel zurĂŒckgefĂŒhrt.
Die vorliegende Arbeit verdeutlicht die Möglichkeiten des Einsatzes konventioneller Kautschuktechnologie bei der Entwicklung mechanisch anpassbarer Komposite mit einem
leicht zugĂ€nglichen Stimulus wie Wasser. Die beiden hier untersuchten Strategien eröffnen enorme Perspektiven bei der Konzeption zukĂŒnftiger intelligenter Materialien.:Contents
1 Introduction 1
1.1 General introduction 1
1.2 Aim and motivation of the work 3
1.3 Scope of the work 5
2 Literature review 7
2.1 Mechanically adaptive polymer composites 7
2.1.1 Mechanical adaptability triggered by different stimuli 7
2.1.2 Water induced mechano-adaptive composites 10
2.1.3 Possible future applications of mechanically adaptive systems 14
2.2 Water absorption in elastomer composites 16
2.2.1 Strategies used for developing water swellable elastomer composites 17
2.2.2 States of water present in the polymers 20
2.2.3 Effect of water absorption on the thermal and mechanical properties 22
2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24
2.2.5 Application of water swellable elastomer composites 25
2.3 Calcium sulphate and its polymorphic transition 26
3 Experimental 30
3.1 Materials 30
3.1.1 Polymers 30
3.1.2 Fillers 31
3.2 Preparation of rubber composites 32
3.2.1 Compounding and mixing 32
3.2.2 Curing study and molding 34
3.3 Characterization 35
3.3.1 Water swelling studies 35
3.3.2 Thermal analysis (DSC and TGA) 36
3.3.3 Dynamic mechanical analysis (DMA) 36
3.3.4 Stressâstrain studies 37
3.3.5 Fourier transform infrared spectroscopy (FTIR) 38
3.3.6 Morphological analysis 39
3.3.7 X-ray diffraction (XRD) 40
3.3.8 Raman spectroscopy 40
4 Results and discussions 42
4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42
4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42
4.1.2 Water absorption behavior of GECO/GEPO blends 49
4.1.3 Effect of water swelling on thermal and mechanical properties 54
4.1.4 Cyclic water swellable characteristics 58
4.2 Thermo-responsive mechano-adaptable composites based on solidâliquid phase transition of absorbed water. 60
4.2.1 Quantitative analysis of in situ formed ice crystals 61
4.2.2 Characterization of the filler (ice crystals) morphology 64
4.2.3 Polymerâfiller interaction 68
4.2.4 Mechanical adaptability analysis 71
4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77
4.3.1 Process and conditions for mechanical adaptability 79
4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83
4.3.3 In situ morphology transformation analysis 86
4.3.4 Mechanical adaptability investigations 89
5 Conclusions and outlook 96
5.1 Conclusions 96
5.2 Outlooks 99
6 References 100
7 Appendix 109
8 Abbreviations 111
9 Symbols 114
10 Figures 117
11 Tables 123
12 Publications 12
Water Responsive Mechano-adaptive Elastomer Composites based on Active Filler Morphology
Get PDFMechanically adaptable elastomer composites are a class of stimuli responsive polymer composites which can reversibly change its mechanical properties when it comes in contact with stimuli like electric field, light, water, solvents, ions and others. Mechanically adaptable composites are mainly inspired from the sea cucumber dermis which has the ability to change the stiffness of its dermis rapidly and reversibly (connecting tissue) when it is immersed in water.
In this work, efforts have been made to develop mechano-adaptive elastomer composites using water as stimuli. In such a case, elastomer composite should absorb water significantly, in order to respond quickly to the stimuli. Therefore, as a first step, stable and repeatable water swellable elastomer composites have been developed by blending epichlorohydrin terpolymer (GECO) with an ethylene oxide based hydrophilic polymer resin (GEPO).
Two different approaches have been thereafter explored to develop mechano-adapative composites based on the developed water swellable elastomer composite. In the first approach, the solidâliquid phase transition of the absorbed water is used to tune mechanical properties around 0 °C. The solidified absorbed water (ice crystals) below 0 °C, acts as reinforcing filler, enhancing the mechanical properties (hard state). The ice crystals liquefy above 0 °C and plasticize the polymer chain, thereby reducing the mechanical properties (soft state). In the second approach, the polymorphic transition of calcium sulphate (CaSO4) in presence of water/heat have been exploited by dispersing it as filler in the developed water swellable elastomer composite. Mechanical adaptability is realized by the reinforcement caused when the composite is exposed to water treatment process. Further, this mechanical strength (reinforcement) can be brought back to its initial soft state (unreinforced state) by the heat treatment process. This reversible reinforcing and non-reinforcing ability of the calcium sulphate filler is attributed to the differences in polymerâfiller interaction, due to the in situ morphology transformation (micro to nano) of the filler particles.
This study reveals the possibility of utilizing conventional rubber technology in developing mechanically adaptable composites with an easily accessible stimulus like water. The two strategies explored here present huge opportunities in developing future smart materials.:Contents
1 Introduction 1
1.1 General introduction 1
1.2 Aim and motivation of the work 3
1.3 Scope of the work 5
2 Literature review 7
2.1 Mechanically adaptive polymer composites 7
2.1.1 Mechanical adaptability triggered by different stimuli 7
2.1.2 Water induced mechano-adaptive composites 10
2.1.3 Possible future applications of mechanically adaptive systems 14
2.2 Water absorption in elastomer composites 16
2.2.1 Strategies used for developing water swellable elastomer composites 17
2.2.2 States of water present in the polymers 20
2.2.3 Effect of water absorption on the thermal and mechanical properties 22
2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24
2.2.5 Application of water swellable elastomer composites 25
2.3 Calcium sulphate and its polymorphic transition 26
3 Experimental 30
3.1 Materials 30
3.1.1 Polymers 30
3.1.2 Fillers 31
3.2 Preparation of rubber composites 32
3.2.1 Compounding and mixing 32
3.2.2 Curing study and molding 34
3.3 Characterization 35
3.3.1 Water swelling studies 35
3.3.2 Thermal analysis (DSC and TGA) 36
3.3.3 Dynamic mechanical analysis (DMA) 36
3.3.4 Stressâstrain studies 37
3.3.5 Fourier transform infrared spectroscopy (FTIR) 38
3.3.6 Morphological analysis 39
3.3.7 X-ray diffraction (XRD) 40
3.3.8 Raman spectroscopy 40
4 Results and discussions 42
4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42
4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42
4.1.2 Water absorption behavior of GECO/GEPO blends 49
4.1.3 Effect of water swelling on thermal and mechanical properties 54
4.1.4 Cyclic water swellable characteristics 58
4.2 Thermo-responsive mechano-adaptable composites based on solidâliquid phase transition of absorbed water. 60
4.2.1 Quantitative analysis of in situ formed ice crystals 61
4.2.2 Characterization of the filler (ice crystals) morphology 64
4.2.3 Polymerâfiller interaction 68
4.2.4 Mechanical adaptability analysis 71
4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77
4.3.1 Process and conditions for mechanical adaptability 79
4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83
4.3.3 In situ morphology transformation analysis 86
4.3.4 Mechanical adaptability investigations 89
5 Conclusions and outlook 96
5.1 Conclusions 96
5.2 Outlooks 99
6 References 100
7 Appendix 109
8 Abbreviations 111
9 Symbols 114
10 Figures 117
11 Tables 123
12 Publications 124Mechanisch-adaptive Elastomer-Verbundwerkstoffe sind eine Klasse von stimuli-responsiven Polymer-Verbundwerkstoffen, welche ihre mechanischen Eigenschaften reversibel verÀndern können, wenn sie mit Stimuli, wie z.B. einem elektrischem Feld, Licht, Wasser, Lösungsmitteln oder Ionen angeregt werden. Mechanisch anpassbare Verbundwerkstoffe sind hauptsÀchlich von der Haut der Seegurke inspiriert, welche in der Lage ist, die Steifigkeit ihrer Dermis (Bindegewebe) beim Eintauchen in Wasser schnell und reversibel zu verÀndern.
Ziel dieser Arbeit war, mechanisch-adaptive Elastomer-Verbundwerkstoffe zu entwickeln, welche Wasser als Stimulus nutzen. FĂŒr diese Anwendung sollte das Elastomermaterial Wasser in einer signifikanten Menge aufnehmen können, um schnell auf den externen Reiz zu reagieren. Daher wurden in einem ersten Schritt stabile und reversibel wasserquellbare Elastomerblends hergestellt, indem ein Epichlorhydrin-Terpolymer (GECO) mit einem hydrophilen Polymerharz auf Ethylenoxidbasis (GEPO) verschnitten wurde.
In der Folge wurden zwei verschiedene AnsĂ€tze zur Entwicklung mechanisch-adaptiver Verbundwerkstoffe auf Basis des so entwickelten wasserquellbaren Elastomerkomposites verfolgt. Beim ersten Ansatz wird der Fest-FlĂŒssig-PhasenĂŒbergang des aufgenommenen Wassers genutzt, um die mechanischen Eigenschaften imâ Bereich von 0 °C einzustellen. Das erstarrte absorbierte Wasser (Eiskristalle) wirkt unter 0 °C als verstĂ€rkender FĂŒllstoff und verbessert die mechanischen Eigenschaften (harter Zustand). Die Eiskristalle verflĂŒssigen sich oberhalb von 0 °C und plastifizieren das Polymer, wodurch die mechanische VerstĂ€rkung wieder herabgesetzt wird (weicher Zustand). Im zweiten Ansatz wurde der polymorphe Ăbergang von Calciumsulfat (CaSO4) in Gegenwart von Wasser bzw. WĂ€rme genutzt, indem es als FĂŒllstoff in einem wasserquellbaren Elastomerkomposit dispergiert wurde. Die mechanische Adaptierbarkeit wird durch die mechanische VerstĂ€rkung erreicht, welche bei der Wasseraufnahme des Verbundwerkstoffes entsteht. AnschlieĂend kann diese mechanische Festigkeit (VerstĂ€rkung) durch eine WĂ€rmebehandlung wieder in ihren ursprĂŒnglichen weichen Zustand (unverstĂ€rkter Zustand) zurĂŒckgefĂŒhrt werden. Diese reversible Schaltbarkeit der VerstĂ€rkungswirkung des Calciumsulfat-FĂŒllstoffes wird auf die Unterschiede in der Polymer-FĂŒllstoff-Wechselwirkung aufgrund der Transformation der in situ-Morphologie (Mikro zu Nano) der FĂŒllstoffpartikel zurĂŒckgefĂŒhrt.
Die vorliegende Arbeit verdeutlicht die Möglichkeiten des Einsatzes konventioneller Kautschuktechnologie bei der Entwicklung mechanisch anpassbarer Komposite mit einem
leicht zugĂ€nglichen Stimulus wie Wasser. Die beiden hier untersuchten Strategien eröffnen enorme Perspektiven bei der Konzeption zukĂŒnftiger intelligenter Materialien.:Contents
1 Introduction 1
1.1 General introduction 1
1.2 Aim and motivation of the work 3
1.3 Scope of the work 5
2 Literature review 7
2.1 Mechanically adaptive polymer composites 7
2.1.1 Mechanical adaptability triggered by different stimuli 7
2.1.2 Water induced mechano-adaptive composites 10
2.1.3 Possible future applications of mechanically adaptive systems 14
2.2 Water absorption in elastomer composites 16
2.2.1 Strategies used for developing water swellable elastomer composites 17
2.2.2 States of water present in the polymers 20
2.2.3 Effect of water absorption on the thermal and mechanical properties 22
2.2.4 Kinetics of diffusion of water in the hydrophilic polymers 24
2.2.5 Application of water swellable elastomer composites 25
2.3 Calcium sulphate and its polymorphic transition 26
3 Experimental 30
3.1 Materials 30
3.1.1 Polymers 30
3.1.2 Fillers 31
3.2 Preparation of rubber composites 32
3.2.1 Compounding and mixing 32
3.2.2 Curing study and molding 34
3.3 Characterization 35
3.3.1 Water swelling studies 35
3.3.2 Thermal analysis (DSC and TGA) 36
3.3.3 Dynamic mechanical analysis (DMA) 36
3.3.4 Stressâstrain studies 37
3.3.5 Fourier transform infrared spectroscopy (FTIR) 38
3.3.6 Morphological analysis 39
3.3.7 X-ray diffraction (XRD) 40
3.3.8 Raman spectroscopy 40
4 Results and discussions 42
4.1 Development of novel water swellable elastomer composites based on GECO/GEPO 42
4.1.1 Miscibility of the polymer blend (GECO/GEPO) systems 42
4.1.2 Water absorption behavior of GECO/GEPO blends 49
4.1.3 Effect of water swelling on thermal and mechanical properties 54
4.1.4 Cyclic water swellable characteristics 58
4.2 Thermo-responsive mechano-adaptable composites based on solidâliquid phase transition of absorbed water. 60
4.2.1 Quantitative analysis of in situ formed ice crystals 61
4.2.2 Characterization of the filler (ice crystals) morphology 64
4.2.3 Polymerâfiller interaction 68
4.2.4 Mechanical adaptability analysis 71
4.3 Utilization of in situ polymorphic alteration of the filler structure in designing mechanically adaptive elastomer composites 77
4.3.1 Process and conditions for mechanical adaptability 79
4.3.2 Investigation of phase transition characteristics of CaSO4 filler 83
4.3.3 In situ morphology transformation analysis 86
4.3.4 Mechanical adaptability investigations 89
5 Conclusions and outlook 96
5.1 Conclusions 96
5.2 Outlooks 99
6 References 100
7 Appendix 109
8 Abbreviations 111
9 Symbols 114
10 Figures 117
11 Tables 123
12 Publications 12
Temperature-Dependent Reinforcement of Hydrophilic Rubber Using Ice Crystals
Get PDFThis is the first study on the impact of ice crystals on glass transition and mechanical behavior of soft cross-linked elastomers. A hydrophilic elastomer such as epichlorohydrin-ethylene oxide-allyl glycidyl ether can absorb about âŒ40 wt % of water. The water-swollen cross-linked network exhibits elastic properties with more than 1500% stretchability at room temperature. Coincidently, the phase transition of water into solid ice crystals inside of the composites allows the reinforcement of the soft elastomer mechanically at lower temperatures. Young's modulus of the composites measured at -20 °C remarkably increased from 1.45 to 3.14 MPa, whereas at +20 °C, the effect was opposite and the Young's modulus decreased from 0.6 to 0.03 MPa after 20 days of water treatment. It was found that a part of the absorbed water, âŒ74% of the total absorbed water, is freezable and occupies nearly 26 vol % of the composites. Simultaneously, these solid ice crystals are found to be acting as a reinforcing filler at lower temperatures. The size of these ice crystals is distributed in a relatively narrow range of 400-600 nm. The storage modulus (EâČ) of the ice crystal-filled composites increased from 3 to 13 MPa at -20 °C. The glass transition temperature (-37 °C) of the soft cross-linked elastomer was not altered by the absorption of water. However, a special transition (melting of ice) occurred at temperatures close to 0 °C as observed in the dynamic mechanical analysis of the water-swollen elastomers. The direct polymer/filler (ice crystals) interaction was demonstrated by strain sweep experiments and investigated using Fourier transform infrared spectroscopy. This type of cross-linked rubber could be integrated into a smart rubber application such as in adaptable mechanics, where the stiffness of the rubber can be altered as a function of temperature without affecting the mechanical stretchability either below or above 0 °C (above the glass temperature region) of the rubber
