Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (106)
- Vortrag (99)
- Beitrag zu einem Tagungsband (20)
- Posterpräsentation (18)
- Beitrag zu einem Sammelband (13)
- Buchkapitel (4)
- Sonstiges (2)
- Forschungsdatensatz (2)
- Corrigendum (1)
- Preprint (1)
Sprache
- Englisch (189)
- Deutsch (77)
- Mehrsprachig (1)
Schlagworte
- AFM (11)
- Low energy electrons (7)
- Raman spectroscopy (7)
- Epoxy (6)
- Atomic force microscopy (5)
- Boehmite (5)
- DNA (5)
- Multiphoton lithography (5)
- Cement (4)
- Dosimetry (4)
- Ectoine (4)
- Friction (4)
- Micropatterning (4)
- Nanocomposite (4)
- Nanocomposites (4)
- Nanolithography (4)
- Polydopamine (4)
- Polymer (4)
- Scanning force microscopy (4)
- Stiffness (4)
- Additive manufacturing (3)
- Adhesion (3)
- Aqueous solution (3)
- Compatible solute (3)
- Composites (3)
- Computed tomography (3)
- DNA damage (3)
- DNA radiation damage (3)
- Degradation (3)
- Direct laser writing (3)
- Electron irradiation (3)
- Electron microscopy (3)
- Fire resistance (3)
- Geant4 (3)
- Hydroxyl radicals (3)
- Indium phosphide (3)
- Intermodulation AFM (3)
- Interpenetrating polymer network (3)
- Interphase (3)
- Intumescence (3)
- Mechanical properties (3)
- Microdosimetry (3)
- Nanofibers (3)
- Nanoparticle (3)
- Radiation damage (3)
- Rheology (3)
- SFM/AFM (3)
- Scanning Force Microscopy (3)
- Surface properties (3)
- XPS (3)
- APTES (2)
- Aluminium oxide hydroxide (2)
- Biological structure (2)
- Broadband dielectric spectroscopy (2)
- CNT (2)
- Cancer (2)
- Carbon nanotubes (2)
- Ceramics (2)
- Curing kinetics (2)
- Cytop (2)
- DNA hybridization (2)
- DSC (2)
- Double-strand break (DSB) (2)
- DySEM (2)
- Early hydration (2)
- Ectoin (2)
- Electrical properties (2)
- Energetic material (2)
- Epoxy nanocomposites (2)
- Epoxy resin (2)
- Fast scanning calorimetry (2)
- Femtosecond laser (2)
- Femtosecond laser irradiation (2)
- Fire retardancy (2)
- Functionalization (2)
- Gamma radiation (2)
- Gasfluorierung (2)
- Glass transition temperature (2)
- Hydroxyectoine (2)
- IR (2)
- Interface/interphase (2)
- LET (2)
- Lethal dose (2)
- Microstructure (2)
- Monte Carlo simulation (2)
- Multi photon lithography (2)
- Multiphoton Lithography (2)
- Nanokomposit (2)
- Nanomechanics (2)
- Organic osmolytes (2)
- Oxidation (2)
- PA 66 (2)
- Photobleaching (2)
- Plasmid DNA in water (2)
- Polycarboxylate ether (2)
- Polycarboxylate ether (PCE) (2)
- Pull-out test (2)
- Radiation damage to biomolecules (2)
- Radiation protection (2)
- Radiation therapy (2)
- Radical scavenger (2)
- Raman imaging (2)
- Recycling (2)
- Rigid amorphous fraction (2)
- SZ2080 negative photo-resist (2)
- Salt (2)
- Single-strand break (SSB) (2)
- Solid-phase extraction (2)
- Solutions (pH, salinity, cosolutes) (2)
- TGA (2)
- TGA-MS (2)
- Thermoset (2)
- Titanium (2)
- Two-photon polymerization (2)
- Water structure (2)
- Weathering (2)
- X-ray scattering (2)
- -COOH und NF2-Gruppen (1)
- 1H-NMR (1)
- 2, 4, 6-trinitrophenol (1)
- 2,4,6-trinitrophenol (TNP) (1)
- 266nm (1)
- 2PP (1)
- 3D printing (1)
- 3D-printing (1)
- AFM cantilever vibration (1)
- AFM force distance curves (1)
- AFM force spectroscopy (1)
- AFM friction analysis (1)
- AFM intermittent contact (1)
- AFM plastic deformation (1)
- AFM stiffness of interface (1)
- ATZ (1)
- Abasic site (1)
- Ablation (1)
- Additiv (1)
- Adherends (1)
- Adhesion force (1)
- Adsorption (1)
- Advanced materials (1)
- Aerospace (1)
- Agarose gel electrophorese (1)
- Aging (1)
- Alterung (1)
- Alumina toughened zirconia (1)
- Amino acid (1)
- Analysis and identification (1)
- Analytical Chemistry (1)
- Analytics (1)
- Antimony clusters (1)
- Antimony sulphide (1)
- Aqueous dispersion (1)
- Atomic and Molecular Physics and Optics (1)
- Atomic-scale friction (1)
- Auger electron spectroscopy (1)
- BET (1)
- BNP (1)
- Bench scale fire testing (1)
- Bench-scale fire test (1)
- Bench‐scale fire testing (1)
- Bending modulus (1)
- Bestrahlung (1)
- Bewitterung (1)
- Biomolecules (1)
- Bleaching (1)
- Blockcopolymer (1)
- Boehmit nanoparticle (1)
- Boehmite nanoparticle (1)
- Boehmite nanoparticles (1)
- Bundesoberbehörden (1)
- Böhmit (1)
- C3A (1)
- C3A hydration (1)
- CPD (1)
- Calibration (1)
- Calibration structure (1)
- Cancer therapy (1)
- Cantilever (1)
- Cantilever motion (1)
- Carbon fibre (1)
- Carbon nanotube CNT (1)
- Catheters (1)
- Cationic photocuring (1)
- Cellulose nanofibrils (1)
- Cement hydration (1)
- Central venous access port (1)
- Ceramic nano particles (1)
- Chain scission (1)
- Coating (1)
- Complication (1)
- Composite structures (1)
- Concrete (1)
- Conductivity microscopy (1)
- Cone calorimeter (1)
- Confocal microscopy (1)
- Confocal raman imaging (1)
- Contact interaction (1)
- Contact mechanics (1)
- Coordination polymer (1)
- Copper (1)
- Corrosion (1)
- Counterions (1)
- Crack propagation energy (1)
- Crosslink density control (1)
- Crosslinking density (1)
- Cubic boron nitride (1)
- Cycloaliphatic epoxy oligosiloxane (1)
- DEA (1)
- DET (1)
- DFG (1)
- DMA (1)
- DNA base damage (1)
- DNA immobilization (1)
- DNA melting temperature (1)
- DNA oligonucleotide (1)
- DNA protection (1)
- DNA strand-break (1)
- DNS (1)
- Damage (1)
- Data (1)
- Delayed addition (1)
- Diethylaluminium phosphinate (1)
- Differential scanning calorimetry (1)
- Differential scanning calorimetry (DSC) (1)
- Diffusion barrier (1)
- Direct Laser Writing (1)
- Dispersion (1)
- Domain barriers (1)
- Dynamic ploughing lithography (1)
- EDX (1)
- EPS (1)
- Ectoine DNA interaction (1)
- Ectoine DNA protection (1)
- Ectoine UV absorption (1)
- Ectoine radiation protection (1)
- Ectoine-DNA binding (1)
- Effective irradiation dose 0.2-16 [Gy] (1)
- Eigenmode (1)
- Elasto-plastic response (1)
- Electrohydraulic effect (1)
- Electron irradiation 30 [kV] (1)
- Electron irradiation of DNA (1)
- Electrospinning (1)
- Electrospun nanocomposite fiber (1)
- Energetische Kristalle (1)
- Energiedissipation im Kontakt (1)
- Epoxy conversion degree (1)
- Epoxy resins (1)
- Epoxy-Anhydrid Duroplast (1)
- Excited states (1)
- Exfoliation (1)
- FIB patterning (1)
- FTIR imaging (1)
- FTIRS (1)
- Fabrication parameters (1)
- Faserverbundwerkstoffe (1)
- Femtosecond laser ablation (1)
- Femtosecond laser pulse (1)
- Ferroelectric (1)
- Ferroelectric domain-walls (1)
- Fiber surfaces (1)
- Fiber toxicology (1)
- Films (1)
- Fire behavior (1)
- Fire protective coating (1)
- Fire residue (1)
- Flame retardance (1)
- Flame retarded polymers (1)
- Flammability (1)
- Flash DSC (1)
- Flexible crystals (1)
- Flexural rigidity (1)
- Fluorescence (1)
- Fluorescence imaging (1)
- Fluorescence labeling (1)
- Fluoropolymers (1)
- Force-Microscopy (1)
- Force-displacement curves (1)
- Force-distance curves (1)
- Force-distance-curve (1)
- Force-microscopy (1)
- Forschungsstrategie (1)
- Fs-time resolved microscopy (1)
- Geant4-DNA (1)
- Gel electrophoresis (1)
- Gene-5 protein (1)
- Glas transition temperature (1)
- Glasfaserverstärkter Kunststoff (1)
- Gold (1)
- Grafting (1)
- Graphene (1)
- Graphs (1)
- Grenzfläche als Material (1)
- Guanine content (1)
- HIPS (1)
- HOPG (1)
- Harmonic (1)
- Harmonics (1)
- Harmonix cantilever (1)
- Height Calibration (1)
- Height calibration (1)
- Heterogeneity (1)
- High throughput (1)
- Hot spot (1)
- Hot spot Theorie (1)
- Hot-spot (1)
- Hydration (1)
- Hydroxyl radical (1)
- I/V-characteristics (1)
- Images (1)
- Imaging theory (1)
- In situ near-infrared (NIR) spectroscopy (1)
- Indium Phosphide (1)
- Infrared nano AFM (1)
- Innovative Werkstoffe (1)
- Instability of TNP (1)
- Instrumentation (1)
- Interdiffusion (1)
- Interface/Interphase (1)
- Interface/Interphase Interdiffusion (1)
- Interfacial shear-strength (1)
- Intermodulation (1)
- Intermodulation-AFM (1)
- Interpenetrating polymer networks (1)
- Interphase/interface (1)
- Ionizing radiation (1)
- Knufia petricola (1)
- Kunststoff (1)
- LEE (1)
- LIPSS (1)
- Laser ablation (1)
- Laser direct writing (1)
- Laser induced periodic surface structures (1)
- Laser induced periodic surface structures (LIPSS) (1)
- Laser materials-processing applications (1)
- Laser radiation effects (1)
- Laser writing (1)
- Laser-induced periodic surface structures (LIPSS) (1)
- Layered silicate (1)
- Lead magnoniobate (1)
- Leichtbau (1)
- Linear energy transfer (1)
- Lithography (1)
- Local electrical-properties (1)
- Low voltage SEM (1)
- Low-energy electrons (1)
- Luminescence (1)
- MDFEM (1)
- Magnesium hydroxide (1)
- Magnéli phases (1)
- Material chemistry (1)
- Mathematical model (1)
- Matrix adhesion (1)
- Maxwell-stress microscopy (1)
- Mechanical flexibility (1)
- Mechanical property (1)
- Mechanical testing (1)
- Mechanism of hot-spot formation (1)
- Melanised microcolonial fungi (MCF) (1)
- Meta material (1)
- Metal matrix (1)
- Metal oxide particles (1)
- Microfabrication (1)
- Microplastics (1)
- Microprinting (1)
- Microscopy (1)
- Microscopy (SFM/AFM) thermal diffusivity (1)
- Mikroplastik (1)
- Mikrorissbildung (1)
- Modal analysis (1)
- Modes (1)
- Modulated Lateral Force Microscopy (1)
- Modulated friction techniques (1)
- Molecular dynamics simulation (1)
- Molecular modeling (1)
- Molecular-dynamics (1)
- Monte Carlo (1)
- Morphology analysis (1)
- Motion detection (1)
- Multi-photon light structuring (1)
- Mussel-inspired materials (1)
- NF2-Gruppe (1)
- Nano (1)
- Nano particles (1)
- Nano scale (1)
- Nano-ceramic-additive-manufacturing photoresin (1)
- NanoCAM (1)
- Nanocomposite fibers (1)
- Nanocorrosion of aluminium and silicon (1)
- Nanodots (1)
- Nanolasers (1)
- Nanomanipulation (1)
- Nanomaterialien (1)
- Nanomechanical charecteisation (1)
- Nanomechanical properties (1)
- Nanometer-scale modification (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Nanosafety (1)
- Nanoscale adsorption and desorption (1)
- Nanostructure (1)
- Nanotribology (1)
- Nanoviscosity (1)
- Near-infrared spectroscopy (1)
- Nondestructive testing (1)
- Nonlinearity (1)
- Normung (1)
- OH radicals (1)
- OH scavenger (1)
- OH-radical (1)
- Oberflächenpotential (1)
- Oberflächensteifigkeit (1)
- Open data on zenodo (1)
- Optical breakdown (1)
- Organic crystal (1)
- Organic nanofibers (1)
- Oxide coating (1)
- Oxide-films (1)
- Oxygen-containing functionalities (1)
- PBS (1)
- PFAS (1)
- Para-hexaphenylene (1)
- Para-sexy-phenylene (1)
- Perfluorinated polymer optical fibers (1)
- Phase-transition (1)
- Phenolic resin (1)
- Phosphinates (1)
- Photoconduction (1)
- Picosecond (1)
- Piezo response force microscopy (1)
- Piezoelectric translator (1)
- Piezoresponse (1)
- Plasmid DNA pUC19 (1)
- Plastic deformation (1)
- Plastikstrategie (1)
- Polyamid-6 (1)
- Polybutadiene (1)
- Polycarbonate (1)
- Polyester (1)
- Polyethylene glycol diacrylate (1)
- Polyglycerol (1)
- Polymer coating (1)
- Polymer embedding (1)
- Polymer matrix (1)
- Polymer optical fibers (1)
- Polymer-matrix composites (PMC) scanning/atomic force (1)
- Polymer-matrix composites (PMCs) (1)
- Polymer-matrix composites (PMC´s) (1)
- Polymer-metal (1)
- Polymers (1)
- Powder processing (1)
- Preferential exclusion (1)
- Principle component analysis (1)
- Probing micromechanical properties (1)
- Pull-out (1)
- Pullulan (1)
- Purification (1)
- Pyrolysis (1)
- Quality infrastructure (1)
- Quantification (1)
- Radiation (1)
- Radiation chemistry (1)
- Radiation-induced attenuation (1)
- Radioprotector ectoine (1)
- Raman Spectroscopy (1)
- Real-time infrared spectroscopy (1)
- Recycling-by-design (1)
- Red phosphorus (1)
- Reference material (1)
- Reference structure (1)
- Referenzmaterialien (1)
- Reinforced composites (1)
- Release (1)
- Residue analysis (1)
- Resonance frequency (1)
- Ringversuch (1)
- Risstrajektorie (1)
- Röntgenstreuung (1)
- SEC (1)
- SEM (1)
- SEM/EDX (1)
- SFM (1)
- SSB (1)
- SYBR gold (1)
- Safety (1)
- Samarium (1)
- Scale (1)
- Scanning probe microscope (1)
- Scanning tunneling microscopy (1)
- Scanning/atomic force microscopy (SFM/AFM) (1)
- SchwarzP cells (1)
- Scratching (1)
- Secondary electrons (1)
- Security (1)
- Security labels (1)
- Self-assembled monolayers (1)
- Semiconductor (1)
- Semiconductor materials (1)
- Shear exfoliation (1)
- Shear strength (1)
- Silane (1)
- Silanized DNA (1)
- Silicon monoxide (1)
- Silicone rubber (SiR) (1)
- Simulation (1)
- Simulierte Sonnenstrahlung (1)
- Single crystal metals (1)
- Single stranded DNA (1)
- Slicers (1)
- Slippage of weakly linked layers (1)
- Slurry (1)
- Sodium chloride (1)
- Solid-liquid interfaces (1)
- Solid-state NMR (1)
- Solution plasma (1)
- Spectroscopy (1)
- Spreading resistance microscopy (1)
- Stainless steel (1)
- Standard time temperature furnace (1)
- Structural characterization (1)
- Structural precision (1)
- Structure propertyrelationship (1)
- Structure-property relationship (1)
- Structured cantilever (1)
- Structure–property correlation (1)
- Structure–property relationship (1)
- Sub-aerial biofilms (SAB) (1)
- Sub-micron electrode (1)
- Sun (1)
- Sunscreen (1)
- Superplasticiser (1)
- Superplasticizer (1)
- Surface (1)
- Surface analysis (1)
- Surface functional groups (1)
- Surface reflectivity (1)
- TDS-GC-MS (1)
- TED-GC-MS (1)
- TGA-FTIR (1)
- Tensile test inside a TEM (1)
- Test artifact (1)
- Test structure (1)
- Therapy (1)
- Thermal degradation (1)
- Thermal diffusivity (1)
- Thermoplastic polyurethane (TPU) (1)
- Thermoplastics (1)
- Thermosets (1)
- Thin film (1)
- Time-resolved measurements (1)
- Tip (1)
- Transparency (1)
- Tunneling microscopy (1)
- Two photon polymerisation (1)
- Two photon polymerization (1)
- Two-photon polymerisatio (1)
- Two-photon polymerisation (1)
- Two-photon-polymerization (1)
- UV absorption (1)
- UV irradiation (1)
- UV photons (1)
- UV protection (1)
- UV radiation (1)
- UV-A (1)
- UV-B (1)
- UV-C (1)
- UV-Vis (1)
- Ultra-precision (1)
- Ultrafast optics (1)
- Van der Waals forces (1)
- Vanadium oxide (1)
- Vibration (1)
- Water (1)
- White light interferometry microscopy (1)
- X-ray diffraction (1)
- X-ray photoelectron spectroscopy (1)
- Young´s modulus (1)
- Young’s modulus (1)
- Yttria stabilized zirconia (1)
- Zerstörungsfreie Prüfung (1)
- Zwitterion (1)
- attraktive Wechelwirkung (1)
- g5p protein (1)
- mechanical nonlinearity (1)
- mechanische Nichtlinearitäten (1)
- stl code (1)
- vibration (1)
- α-1,4- and α-1,6-glucans (1)
Organisationseinheit der BAM
- 6 Materialchemie (46)
- 6.6 Physik und chemische Analytik der Polymere (46)
- 6.1 Oberflächen- und Dünnschichtanalyse (9)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (6)
- 5 Werkstofftechnik (4)
- 6.3 Strukturanalytik (3)
- 7 Bauwerkssicherheit (3)
- 7.4 Baustofftechnologie (3)
- 4 Material und Umwelt (2)
- 5.1 Mikrostruktur Design und Degradation (2)
Paper des Monats
- ja (3)
Eingeladener Vortrag
- nein (99)
Though the reinforcing properties of inorganic particles in thermosetting nanocomposites, has been exploited, the integration of nanoparticles continues to be challenging in terms of their homogeneous distribution and their manipulation which can contribute to occupational hazards. Due to a second encapsulations of nanoparticles, electrospun nanocomposite fibers containing nanoparticles might be an alternative for overcoming these issues, as the fiber nonwovens contains the nanoparticles allowing for safer manipulation. Here, the morphology, and the thermal properties of electrospun polycarbonate fibers containing taurine modified boehmite nanoparticles (BNP) are investigated by means of small and wide-angle X-ray scattering as well as fast scanning and temperature modulated fast scanning calorimetry for the first time. The latter techniques allow the investigation of the thermal properties of single fibers at heating rates up to 10^4 K s^-1 keeping its structure intact. A quantitative analysis of the scattering data reveals a porous structure of the fibers. The porous structure is quantified regarding the pore volume and the pore size. A constant amount of aggregation is found even for the highly BNP loaded fibers. Thermal analysis on the fibers reveals a rigid amorphous fraction (RAF) where it is known that RAF determinates the properties of a nanocomposite to a large extent. For the fibers RAF amounts up to 40 wt%, which is essential higher compared to equally formulated PC/BNP composite cast films. The RAF in the case of the fibers, is not only due to the presence of particles in the polymer but also due to orientation effects induced by the electrospinning process.
A key application of atomic force microscopy (AFM) is the measurement of physical properties at sub-micrometer resolution. Methods such as force–distance curves (FDCs) or dynamic variants (such as intermodulation AFM (ImAFM)) are able to measure mechanical properties (such as the local stiffness, kr) of nanoscopic heterogeneous materials. For a complete structure–property correlation, these mechanical measurements are considered to lack the ability to identify the chemical structure of the materials. In this study, the measured attractive force, Fattr, acting between the AFM tip and the sample is shown to be an independent measurement for the local chemical composition and hence a complete structure–property correlation can be obtained. A proof of concept is provided by two model samples comprised of (1) epoxy/polycarbonate and (2) epoxy/boehmite. The preparation of the model samples allowed for the assignment of material phases based on AFM topography. Additional chemical characterization on the nanoscale is performed by an AFM/infrared-spectroscopy hybrid method. Mechanical properties (kr) and attractive forces (Fattr) are calculated and a structure–property correlation is obtained by a manual principle component analysis (mPCA) from a kr/Fattr diagram. A third sample comprised of (3) epoxy/polycarbonate/boehmite is measured by ImAFM. The measurement of a 2 × 2 µm cross section yields 128 × 128 force curves which are successfully evaluated by a kr/Fattr diagram and the nanoscopic heterogeneity of the sample is determined.
Comprehensive Characterization of APTES Surface Modifications of Hydrous Boehmite Nanoparticles
(2020)
Hydrous boehmite (γ-AlOOH) nanoparticles (BNP) show great potential as nanoscale filler for the fabrication of fiber reinforced nanocomposite materials. Notably, the particle−matrix interaction has been demonstrated to be decisive for improving the matrix-dominant mechanical properties in the past years. Tailoring the surface properties of the nanofiller enables to selectively design the interaction and thus to exploit the benefits of the nanocomposite in an optimal way. Here, an extensive study is presented on the binding of (3-aminopropyl)triethoxysilane (APTES), a common silane surface modifier, on BNP in correlation to different process parameters (concentration, time, temperature, and pH). Furthermore, a comprehensive characterization of the modified BNP was performed by using elemental analysis (EA), thermogravimetric analysis (TGA) coupled with mass spectrometry (TGA-MS), and Kaiser’s test (KT). The results show an increasing monolayer formation up to a complete surface coverage with rising APTES concentration, time, and temperature, resulting in a maximal grafting density of 1.3 molecules/nm². Unspecific multilayer formation was solely observed under acidic conditions. Comparison of TGA-MS results with data recorded from EA, TGA, and KT verified that TGA-MS is a convenient and highly suitable method to elucidate the ligand binding in detail.
The presence of polycarboxylate ether (PCE) based superplasticizers (SPs) has an enormous influence on the early hydration of cement. The hydration is retarded and the timing of formation and the morphology of hydrates is affected. This short paper presents experimental results about the influence of delayed addition time of PCE SPs on hydration of cement and alite pastes, investigated by isothermal heat flow calorimetry. For cement as well as for alite pastes the hydration is retarded with SP, whereby the high charge PCE has a stronger retarding effect than the low charge PCE. The retardation caused by PCE is much more pronounced for alite than for cement mixes. If PCE is added later to the mix, the induction period is shortened and the hydration is accelerated compared to simultaneous addition. This applies for cement and alite pastes. With delayed PCE addition the alite shows a clearly less retarded setting and main hydration than after simultaneous addition. It is obvious that for alite pastes there is less retardation the later the addition of SP.
In this work, a novel boehmite (BA)-embedded organic/inorganic nanocomposite coating based on cycloaliphatic epoxy oligosiloxane (CEOS) resin was fabricated applying UV-induced cationic polymerization. The main changes of the material behavior caused by the nanofiller were investigated with regard to its photocuring kinetics, thermal stability, and glass transition. The role of the particle surface was of particular interest, thus, unmodified nanoparticles (HP14) and particles modified with p-toluenesulfonic acid (OS1) were incorporated into a CEOS matrix in the concentration range of 1–10 wt.%. Resulting nanocomposites exhibited improved thermal properties, with the glass transition temperature (Tg) being shifted from 30 °C for unfilled CEOS to 54 °C (2 wt.% HP14) and 73 °C (2 wt.% OS1) for filled CEOS. Additionally, TGA analysis showed increased thermal stability of samples filled with nanoparticles. An attractive interaction between boehmite and CEOS matrix influenced the curing. Real-time infrared spectroscopy (RT-IR) experiments demonstrated that the epoxide conversion rate of nanocomposites was slightly increased compared to neat resin. The beneficial role of the BA can be explained by the participation of hydroxyl groups at the particle surface in photopolymerization processes and by the complementary contribution of p-toluenesulfonic acid surface modifier and water molecules introduced into the system with nanoparticles.
The presence of polycarboxylate ether (PCE) based superplasticizers (SPs) has enormous influence on the early hydration of cement. C3A as the most reactive phase of Portland cement plays a significant role in early hydration reactions and affects the rheological performance. Therefore, this paper presents experimental results about the influence of delayed addition of PCEs on the Hydration of cement and C3A-gypsum pastes investigated by isothermal heat flow calorimetry. Complementary in-situ XRD was carried out on C3A pastes to analyze hydration and phase changes related to the addition of PCE.
Cement pastes with a delayed addition of PCE showed less Retardation compared to simultaneous addition. The alteration caused by PCE is much more pronounced for C3A-gypsum mixes. With a delayed addition of SP, the hydration of C3A is less retarded or even accelerated. It is obvious that there is less retardation the later the addition of SP. Furthermore, the PCE alter the hydration of C3A when added delayed and exhibit changes in kinetics and hydration rates. XRD results showed that more C3A is dissolved in the presence of PCE. Also, the gypsum depletion occurs earlier in the presence of PCE and even faster with delayed addition. Without PCE AFm starts to form just after the gypsum depletion. However, in the presence of PCE AFm already starts to form at the beginning of the hydration. Due to the faster gypsum depletion in the presence of PCE, also the transformation from ettringite into AFm begins earlier, but takes longer as without SP.
Understanding the interaction between boehmite and epoxy and the formation of their interphases with different mechanical and chemical structures is crucial to predict and optimize the properties of epoxy-boehmite nanocomposites. Probing the interfacial properties with atomic force microscopy (AFM)-based methods, especially particle-matrix long-range interactions, is challenging. This is due to size limitations of various analytical methods in resolving nanoparticles and their interphases, the overlap of interphases, and the effect of buried particles that prevent the accurate interphase property measurement. Here, we develop a layered model system in which the epoxy is cured in contact with a thin layer of hydrothermally synthesized boehmite. Different microscopy methods are employed to evaluate the interfacial properties. With intermodulation atomic force microscopy (ImAFM) and amplitude dependence force spectroscopy (ADFS), which contain information about stiffness, electrostatic, and van der Waals forces, a soft interphase was detected between the epoxy and boehmite. Surface potential maps obtained by scanning Kelvin probe microscopy (SKPM) revealed another interphase about one order of magnitude larger than the mechanical interphase. The AFM-infrared spectroscopy (AFM-IR) technique reveals that the soft interphase consists of unreacted curing agent. The long-range electrical interphase is attributed to the chemical alteration of the bulk epoxy and the formation of new absorption bands.