3D textile performs offer a high potential to increase mechanical properties of composites and they can reduce the production steps and costs as well. The variety of woven structures is enormous. The algorithms based on the conventional weaving notation can only represent the possible woven structures in a limited way. Within the scope of this dissertation, a new weaving notation was developed in order to analyze the multilayer woven structures analytically. Technological solutions were developed in order to guarantee a reproducible preform production with commingled hybrid yarns. Terry weaving technique can be utilized to create vertical connections on carrier fabrics, which makes it suitable for the development of complex profiles. A double rapier weaving machine was modified with electronically controlled terry weaving and pneumatic warp yarn pull-back systems. Various spacer fabrics and 3D profiles were developed. A linear take-up system is developed to assure reproducible preform production with a minimum material damage. Integrated cutting and laying mechanisms on the take-up system provides a high level of automation.

Organic hybrid composites based on carboxylated nitrile rubber and nylon-12 reinforced with mercerized and diisocyanated lignocellulose residue (LCR) was prepared. The influence of the LCR on the viscoelastic properties of these organic hybrids was investigated by dynamic mechanical analysis and thermal analysis (differential scanning calorimetry (DSC)). It is found that either the position of the damping peak was shifted to higher values or the intensity of the damping peak was significantly increased with LCR. These results could imply that the LCR enhanced the damping properties of the composites. The thermal stability of the composites was evaluated with the mean values obtained using thermogravimetrical analysis. The decomposition rate was investigated using differential thermal gravimetry. The crystallization behavior of the prepared composites was checked by DSC.

This work, conceived as a second step in the development of high-performance damping materials suitable for seismic application, describes the preparation and characterization of complex natural rubber-based composites containing hybrid nano- and conventional fillers. The cluster–cluster aggregation model was used to assess the apparent filler networking energy. The values obtained suggested that the presence of the hybrid nanofiller strengthens the filler networking. The same model was used to understand the mechanisms of energy dissipation. The damping coefficient was found to be in the sought range between 10% and 20% (at 0.5 Hz and high shear strain).

Fiber-reinforced composites are currently being used in a wide range of lightweight constructions. Function integration, in particular, offers possibilities to develop new, innovative products for a variety of applications. The large amount of experimental testing required to investigate these novel material combinations often hinders their use in industrial applications. This paper presents an approach that allows the layout of adaptive, fiber-reinforced composites by the use of numerical simulation. In order to model the adaptive characteristics of this functional composite with textile-integrated shape memory alloys, a thermo-elastic simulation is considered by using the Finite Element method. For the numerical simulation, the parameters of the raw materials are identified and used to generate the model. The results of this simulation are validated through deflection measurements with a specimen consisting of a glass fiber fabric with structurally integrated shape memory alloys and an elastomeric matrix system. The achieved experimental and numerical results demonstrate the promising potential of adaptive, fiber-reinforced composites with large deformation capabilities.

Nowadays, exceptional advantages of silk fibroin over synthetic and natural polymers have impelled the scientists to application of this biomaterial for tissue engineering purposes. Recently, we showed that embedding natural degummed silk fibers in regenerated Bombyx mori silk-based scaffold significantly increases the mechanical stiffness, while the porosity of the scaffolds remains the same. In the present study, we evaluated degradation rate, biocompatibility and regenerative properties of the regenerated 2% and 4% wt silk-based composite scaffolds with or without embedded natural degummed silk fibers within 90 days in both athymic nude and wild-type C57BL/6 mice through subcutaneous implantation. In all scaffolds, a suitable interconnected porous structure for cell penetration was seen under scanning electron microscopy. Compressive tests revealed a functional relationship between fiber reinforcement and compressive modulus. In addition, the fiber/fibroin composite scaffolds support cell attachment and proliferation. On days 30 to 90 after subcutaneous implantation, the retrieved tissues were examined via gross morphology, histopathology, immunofluorescence staining and reverse transcription-polymerase chain reaction as shown in Figure 1. Results showed that embedding the silk fibers within the matrix enhances the biodegradability of the matrix resulting in replacement of the composite scaffolds with the fresh connective tissue. Fortification of the composites with degummed fibers not only regulates the degradation profile but also increases the mechanical performance of the scaffolds. This report also confirmed that pore size and structure play an important role in the degradation rate. In conclusion, the findings of the present study narrate key role of additional surface area in improving in vitro and in vivo biological properties of the scaffolds and suggest the potential ability of these fabricated composite scaffolds for connective tissue regeneration.

Mechanically 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 solid–liquid 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 polymer–filler 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 Stress–strain 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 solid–liquid 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 Polymer–filler 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 124 / Mechanisch-adaptive Elastomer-Verbundwerkstoffe sind eine Klasse von stimuli-responsiven Polymer-Verbundwerkstoffen, welche ihre mechanischen Eigenschaften reversibel verändern können, wenn sie mit Stimuli, wie z.B. einem elektrischem Feld, Licht, Wasser, Lösungsmitteln oder Ionen angeregt werden. Mechanisch anpassbare Verbundwerkstoffe sind hauptsächlich von der Haut der Seegurke inspiriert, welche in der Lage ist, die Steifigkeit ihrer Dermis (Bindegewebe) beim Eintauchen in Wasser schnell und reversibel zu verändern. Ziel dieser Arbeit war, mechanisch-adaptive Elastomer-Verbundwerkstoffe zu entwickeln, welche Wasser als Stimulus nutzen. Für 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 Ansätze zur Entwicklung mechanisch-adaptiver Verbundwerkstoffe auf Basis des so entwickelten wasserquellbaren Elastomerkomposites verfolgt. Beim ersten Ansatz wird der Fest-Flüssig-Phasenübergang des aufgenommenen Wassers genutzt, um die mechanischen Eigenschaften im‚ Bereich von 0 °C einzustellen. Das erstarrte absorbierte Wasser (Eiskristalle) wirkt unter 0 °C als verstärkender Füllstoff und verbessert die mechanischen Eigenschaften (harter Zustand). Die Eiskristalle verflüssigen sich oberhalb von 0 °C und plastifizieren das Polymer, wodurch die mechanische Verstärkung wieder herabgesetzt wird (weicher Zustand). Im zweiten Ansatz wurde der polymorphe Übergang von Calciumsulfat (CaSO4) in Gegenwart von Wasser bzw. Wärme genutzt, indem es als Füllstoff in einem wasserquellbaren Elastomerkomposit dispergiert wurde. Die mechanische Adaptierbarkeit wird durch die mechanische Verstärkung erreicht, welche bei der Wasseraufnahme des Verbundwerkstoffes entsteht. Anschließend kann diese mechanische Festigkeit (Verstärkung) durch eine Wärmebehandlung wieder in ihren ursprünglichen weichen Zustand (unverstärkter Zustand) zurückgeführt werden. Diese reversible Schaltbarkeit der Verstärkungswirkung des Calciumsulfat-Füllstoffes wird auf die Unterschiede in der Polymer-Füllstoff-Wechselwirkung aufgrund der Transformation der in situ-Morphologie (Mikro zu Nano) der Füllstoffpartikel zurückgeführt. Die vorliegende Arbeit verdeutlicht die Möglichkeiten des Einsatzes konventioneller Kautschuktechnologie bei der Entwicklung mechanisch anpassbarer Komposite mit einem leicht zugänglichen Stimulus wie Wasser. Die beiden hier untersuchten Strategien eröffnen enorme Perspektiven bei der Konzeption zukünftiger 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 Stress–strain 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 solid–liquid 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 Polymer–filler 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 124

The Joule heating of carbon fiber-based textiles enables an energy- and cost-efficient processing of carbon fiber reinforced thermoplastic parts. This article introduces a new method to pass direct current into a dry, not pre-consolidated hybrid yarn textile based on recycled carbon fibers and polyamide 6 fibers. The aim is to melt polyamide fibers, subsequently impregnate carbon fibers, and finally consolidate the material to form a composite part in a single process step. To increase the reliability of this technology, the electrical properties and the behavior of the material during the heating process must be thoroughly investigated. It will be addressed how the material is characterized during the process and how the changing resistivity of the textile affects the current flow between the electrodes to generate intrinsic heat. Moreover, a method to determine the effective material resistivity by finite element simulation on the fiber scale based on a CT scan is presented. Thus, a validated material model with respect to the temperature development in the textile based on ρ = ρ (T) was established.

Der in den Ingenieurwissenschaften zunehmend populäre Einsatz der Origami-Technik eröffnet neue Möglichkeiten zur Herstellung von effizienten Tragkonstruktionen [1]–[5]. In Verbindung mit leistungsfähigen, zementbasierten Verbundwerkstoffen bietet die Origami-Technik einen innovativen Ansatz für Entwurf und Realisierung von leichten tragenden Strukturen nach dem Prinzip form follows force – dem Grundgedanken des SPP 1542. [Aus: Motivation und Zielsetzung] / The increasingly popular use of origami technology in the engineering sciences opens up new possibilities for the manufacture of efficient load-bearing structures [1]–[5]. In combination with high-performance, cement-based composite materials, origami technology of ers an innovative approach to the design and realisation of lightweight load-bearing structures based on the principle form follows force –the basic idea of SPP 1542. [Off: Motivation and objectives]

Carbon fibre reinforced plastic (CFRP) materials are of interest for the aerospace and aviation industry to master growing economic and ecological challenges. In contrast to conventional metallic materials, they offer both higher specific material properties, such as strengths, stiffnesses, and an increased energy absorption capacity in case of impact loading scenarios. Additionally, the possibility of integrating functional elements, such as actuators and sensors, predestine CFRP for the development of more lightweight structural components. In this study, a generic composite structure is instrumented with embedded piezo ceramic sensor elements. A technology for TEmSAL is presented and applied within an autoclave manufacturing process. Aspects of the designing process, manufacturing and instrumentation as well as experimental impact sensing and self-actuation results are presented and discussed.

The PhD thesis provides detailed description of a successful development of MgO and TiO2 particle reinforced Steel Ceramic Composites (SCC) for molten aluminum alloy applications. For this purpose, the influence of MgO and TiO2 addition and subsequent pre-oxidation surface treatment on the structure of SCCs and their corrosion resistance against long-term contact with liquid aluminum alloys was investigated. The initiation and progression of corrosion processes were thoroughly analyzed by means of newly developed DSC-aided corrosion tests, high temperature electrochemical studies and adapted wettability measurements. The gained insights led to the recognition of most important factors contributing to the corrosion, including both the electrochemical and the chemical driving forces arising between the SCCs and aluminum alloy. The evaluation of long-term corrosion resistance was performed with the help of finger immersion tests, crucible corrosion tests and subsequent SEM/EDS/EBSD and XRD analyses aiming at the determination of elements most prone to the dissolution in the liquid aluminum alloy and formation of corrosion phases. The pre-oxidized MgO reinforced SCC revealed superior corrosion resistance, being capable of withstanding more than 168 h of contact with liquid aluminum alloy.:Table of content 1 Introduction 1 2 Theoretical background 5 2.1 Wettability measurements 5 2.2 Electrochemical behavior of SCC/molten aluminum alloy material pair 8 2.3 Steel-based materials/molten aluminum alloy reaction 13 2.4 Long-term corrosion mechanisms 16 2.5 Differential Scanning Calorimetry for corrosion precipitation analysis 18 2.6 Corrosion of steel and SCCs during long-term contact with aluminum alloys 19 2.7 Protective coatings and surface treatment of steel and Steel Ceramic Composites 21 2.7.1 Protective coatings against molten aluminum alloys 21 2.7.2 Oxidation kinetics 22 3 Materials and Methods 25 3.1 Materials and Composites Manufacturing 26 3.2 Investigation of corrosion phase formation via DSC-aided corrosion tests 29 3.3 High temperature electrochemical studies 30 3.4 Elaboration of suitable surface pre oxidation for SCCs 33 3.5 Wettability Tests 34 3.6 Finger immersion tests 35 3.7 Crucible Corrosion Tests 36 4 Results and Discussion 41 4.1 Investigation of corrosion phase formation using DSC-aided corrosion tests 41 4.1.1 Determination of reference information for DSC-aided corrosion test 41 4.1.2 Influence of the sample/melt contact duration on the alteration of DSC signal – elaboration of suitable corrosion test conditions. 44 4.1.3 Investigation of 120 min contact time between 316L40TiO2 and 316L40MgO Steel Ceramic Composites with aluminum alloy on the formation of corrosion phases in the melt 47 4.1.4 SEM/EDS microscopical analysis of 316L sample after DSC-aided corrosion test with AlSi7Mg0.3 aluminum alloy for 120 min 51 4.1.5 SEM/EDS microscopical analysis of 316L40TiO2 sample after DSC-aided corrosion test with AlSi7Mg0.3 aluminum alloy for 120 min 53 4.1.6 SEM/EDS microscopical analysis of 316L40MgO sample after DSC-aided corrosion test with AlSi7Mg0.3 aluminum alloy for 120 min 55 4.2 High temperature electrochemical studies of SCCs 60 4.2.1 Evaluation of thermal and chemical stability of selected three-electrode cell materials 60 4.2.2 Differential Potential 61 4.2.3 Impedance Spectroscopy and Potentiodynamic Polarization 64 4.2.4 Microscopical analysis of WE after the electrochemical experiment 68 4.3 Surface treatment of SCCs 79 4.3.1 Dilatometry and Thermogravimetry of SCCs during pre-oxidation 79 4.3.2 Preliminary evaluation of morphology of the SCCs cross-section after pre oxidation at different temperatures and for different durations 83 4.3.3 Detailed SEM/EDS/XRD structure analysis of selected pre-oxidized SCCs 87 4.4 Wettability of aluminum alloy on SCCs 102 4.4.1 Characterization of substrates surface 102 4.4.2 Wetting angle at the drop release 102 4.4.3 Wetting angle 30 min after reaching 850 °C 104 4.4.4 Evaluation of the droplet/substrate cross-section 105 4.5 Finger Immersion Tests 107 4.5.1 Preliminary evaluation of peroxidized SCCs after immersion test 107 4.5.2 Analysis of 316L40TiO2 immersion sample pre oxidized at 850 °C for 24 h 111 4.5.3 Analysis of 316L40TiO2 immersion sample pre-oxidized at 1000 °C for 24 h 112 4.5.4 Analysis of 316L40MgO immersion sample pre oxidized at 850 °C for 24 h 113 4.5.5 Analysis of 316L40MgO immersion sample pre-oxidized at 1000 C for 24 h 114 4.6 Crucible Corrosion Tests 115 4.6.1 Preliminary evaluation of crucible corrosion test results 115 4.6.2 Analysis of 316L40TiO2 sample pre oxidized at 850 °C for 24 h after the crucible corrosion test for 24 h 119 4.6.3 Analysis of 316L40TiO2 sample pre-oxidized at 1000 °C for 24 h after the crucible corrosion test for 168 h 120 4.6.4 Analysis of 316L40MgO sample pre-oxidized at 850 °C for 24 h after the crucible corrosion test for 24 h 122 4.6.5 Analysis of 316L40MgO sample pre-oxidized at 1000 °C for 24 h after the crucible corrosion test for 168 h 125 4.6.6 Analysis of the microstructure of aluminum alloy after crucible corrosion tests 128 4.6.7 Evaluation of contamination of aluminum alloy after crucible corrosion tests 133 Conclusions 137 References 145 Appendixes 161 Appendix A: Preliminary Investigations 161 A.1: Preparation of SCC granulates 161 A.2: Evaluation of properties of composites pressed from granulates 162 Appendix B: Constructions and Designs 169 B.1. Three-Electrode Cell – for high temperature electrochemical measurements with molten aluminum alloys as reference electrode 169 B.2. Capillary System – for capillary purification technique wettability measurements with aluminum alloys 177 Appendix C: Auxiliary Investigations 184 C.1 Detailed SEM/EDS analysis of pre-oxidized SCCs 184 C.2 SEM/EDS analysis of SCCs after 96 h Finger Immersion Tests in aluminum alloy 207