Microstructural mechanical and optical characterisation of polymer infiltrated (Al/Ti/Zr) oxide-reinforced nano-SiO 2 dual networks

Excess surface work—A modelless way of getting surface energies and specific surface areas directly from sorption isotherms

Water vapor sorption surface areas and sorption energies of untreated and thermally modified Norway spruce [Picea abies (L.) Karst.], sycamore maple (Acer pseudoplatanus L.) and European ash (Fraxinus excelcior L.) were investigated by means of dynamic vapor sorption (DVS) measurements and excess surface work (ESW) evaluation method, respectively. Adsorption and desorption experiments in the hygroscopic range and desorption tests from water saturation were conducted. Thermodynamically, ESW is the sum of the surface free energy and the isothermal isobaric work of sorption. From the amount adsorbed in the first minimum a specific surface area similar to the BET surface area can be obtained. The results show that untreated spruce has a significantly higher specific water vapor sorption surface and sorption energy compared to both hardwoods maple and ash. Thermal modification of the woods leads to a significant reduction of water vapor sorption surface and sorption energy. The determined surface area and energy are higher in desorption direction than in adsorption direction, whereby the highest values in desorption direction from water saturation, especially for maple and ash, were obtained. The surface areas calculated by means of the ESW method are similar to the surface areas calculated by means of the BET method, particularly in adsorption direction.

Effect of different surface treatments and thermomechanical aging on the ion elution of CAD-CAM materials

Description of Gas Adsorption Isotherms on Porous and Dispersed Systems with the Excess Surface Work Model

Development of zirconia-based polymer-infiltrated ceramic network for dental restorative material

Polymer infiltrated ceramic network (PICN) composites are an increasingly popular dental restorative material that offer mechanical biocompatibility with human enamel. This study aimed to develop a novel PICN composite as a computer-aided design and computer-aided manufacturing (CAD/CAM) block for dental applications. Several PICN composites were prepared under varying conditions via the sintering of a green body prepared from a silica-containing precursor solution, followed by resin infiltration. The flexural strength of the PICN composite block (107.8–153.7 MPa) was similar to a commercial resin-based composite, while the Vickers hardness (204.8–299.2) and flexural modulus (13.0–22.2 GPa) were similar to human enamel and dentin, respectively. The shear bond strength and surface free energy of the composite were higher than those of the commercial resin composites. Scanning electron microscopy and energy dispersive X-ray spectroscopic analysis revealed that the microstructure of the composite consisted of a nanosized silica skeleton and infiltrated resin. The PICN nanocomposite block was successfully used to fabricate a dental crown and core via the CAD/CAM milling process.

The water vapour sorption data of untreated (Wuntr), acetylated (Wac) and formaldehyde-treated (WFA) Scots pine (Pinus sylvestris L.) sapwood were analysed in terms of their sorption kinetics and were transformed into excess surface work (ESW) isotherms. The sorption kinetics were studied by fitting the non-linear parallel exponential kinetics (PEK) model to the experimental data in which the sorption kinetics curve is composed of two processes (fast and slow components). Wac and WFA showed evident differences in their sorption kinetics and their thermodynamic sorption behaviour. In contrast to acetylation, formalisation influenced both the extent of the slow sorption process and the shape of its pseudoisotherm. For Wuntr and Wac, it appears that some water associated with the slow process is adsorbed at sites for fast sorption newly generated upon swelling (previously postulated as extra water) and subsequently desorbed by the fast process. For WFA, the formation of extra water hardly occurs. ESW was reduced through acetylation with a constant factor over the whole hydroscopic range, whereas the ESW of WFA was reduced only after reaching the monolayer capacity compared to its control. The sorption behaviour of Wac was solely determined by cell wall bulking, whereas that of WFA was governed by the increased matrix stiffness due to cross-linking of the cell wall polymers.

Moisture Dependence of Pore Size and Specific Surface Area of Hardened Cement Paste Determined with Saxs and Inverse Gas Chromatography

Pore structural changes in hardened cement pastes, subjected to drying and wetting/drying cycles, were studied at micrometer and nanometer levels. Characterization techniques included Nuclear Magnetic Resonance (NMR), nitrogen and water vapor adsorption, mercury intrusion porosimetry (MIP) and under-water weighing. Coarsening of pore structure was observed with MIP and increase in the true density of C-S-H was suggested by the result of under-water weighing. Decrease in specific surface area due to drying was observed with nitrogen adsorption, and water vapor adsorption associated with Excess Surface Work (ESW) analysis suggested a development of cohesive structure in C-S-H. NMR confirmed polymerization of silicate anion chains. The drying-induced coarsening of pore structure is probably attributed to polymerization of silicate anion chains and development of cohesive structure in C-S-H.

Comparison of human enamel and polymer-infiltrated-ceramic-network material “ENAMIC” through micro- and nano-mechanical testing

Pore size distribution of MCM-41-type silica materials from pseudomorphic transformation - A minimal input data approach based on excess surface work

Energetic Classification of Adsorption Isotherms

Formation of dual quasi-continuous networked structure and its strengthening effect in Ti-6Al-4V alloy reinforced with graphene via powder bed fusion

Fabrication and characterization of polymer infiltrated ceramic networks (PICNs) were undertaken for use in dentistry. Calcia-stabilized tetragonal zirconia (7-tCSZ) nanoparticles were synthesized via a modified co-precipitation. The composition and particle size of the prepared nanoparticles were studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Densification parameters of porous ceramic samples, with varying amounts of 7-tCSZ, 0, 5, 10, and 15 wt.%, and PICN materials were examined using the Archimedes principle. The flexural strength and elastic modulus of PICNs were measured using a three-point bending strength test. The microhardness and fracture toughness were determined using Vickers microhardness and V-notched bars tests, respectively. The microstructure was investigated for selected materials before and after polymer infiltration using scanning electron microscopy (SEM). The results revealed that the samples with 10 and 15 wt.% of nano-tetragonal zirconia showed the highest elastic modulus (8.24 GPa) and fracture toughness (1.82 MPa m1/2), respectively, which is attributed to transformation toughening of zirconia. The flexural strength and microhardness of PICNs were in the range 66.14–71.72 MPa, 0.18–0.19 GPa, respectively, whilst the brittleness index was maximally 0.21 μm−½, which is significantly below the ultimate brittleness index (4.3 μm−1/2) allowing machinability. Conclusively, the inclusion of nanometric zirconia posed a dramatic enhancement of the mechanical properties without affecting the machinability of these biomimetic materials, making them similar to natural dentin in terms of the elastic modulus and fracture toughness along with ease of machinability, which renders them promising as indirect dental restorative materials.

Dynamic vapour sorption and water-related properties of thermally modified Scots pine (Pinus sylvestris L.) wood pre-treated with proton acid