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This study investigated the effect of the Cr limits on the microstructure and mechanical properties of 316L alloy. Five 316L alloys with varying Cr contents (16.8, 17.1, 17.3, 17.8 and 18.8 wt.%) were produced by the powder metallurgy (P/M) method. Microstructure studies and phase analysis were performed with a scanning electron microscope (SEM), optical microscopy (OM), and energy dispersive spectrometry (EDS). Tensile tests and hardness measurements were performed to evaluate the hardness, strength, and ductility of the alloys. The results showed that Cr addition affected the porosity and grain size of the alloys, as well as the formation of precipitates. The ultimate tensile strength reached a maximum at 17.3 wt.% Cr and then decreased with further Cr addition. Ductility decreased with increasing Cr under the influence of precipitates formed and changes in microstructure. On the other hand, the hardness increased with increasing Cr inversely to the ductility. [ABSTRACT FROM AUTHOR]

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This paper provides a current overarching review of several commonly used carbon nanomaterials applied within cementitious composites. It reviews the typical weight percentages used within mixes from several researchers in the field and assesses the application of these nanomaterials on the mechanical properties. Mechanical properties covered include compressive strength, flexural strength and tensile strength as well as elastic modulus. It was clear from this extensive but initial review that the dispersion methods and techniques used during mixing not only influenced the mechanical properties but also influenced the percentages of nanomaterials used in the mixes. This leads to a further review of dispersion methods and dispersion measurement techniques in order to gain insight into the best approach to take. The effect of dispersion methods on the quantities of nanomaterials used in mixes raised an interesting, last review on pricing comparisons (2020) and the development of a cost-to -weight ratio to better evaluate and compare between options from a cost perspective. Recommendations from this extensive review include; low percentage of graphene oxide provides better improvement compared with other carbon nanomaterials; Use of superplasticiser in mixes such as ADVA 210 to better aid dispersion; use of ultra-sonication for a short cycle to improve dispersion; and finally, a mixed mode approach to the measurement of dispersion in mixes which includes scanning electron microscope (SEM) + ultraviolet–visible spectroscopy (UV–Vis) testing at solution phase + Mechanical properties after 28 days. [ABSTRACT FROM AUTHOR]

In light of environmental concerns such as global warming, there has been a dramatic rise in natural fiber concrete (NFC) research and development. The advantages of these materials over others, such as low environmental impact and minimal cost, warrant interest and support their potential across various applications. This study investigates mechanical properties and micro-structural analysis for M70 grade of high-strength concrete (HSC) under the effect of natural fiber with alccofine. Cement was partially replaced in this investigation by 15 % alccofine content. In this experiment, natural banana fiber (BF) and coir fiber (CF) were selected and added in concrete at 0.5 %, 1 %, 1.5 %, and 2 % by volume. Nine concrete mix compounds were developed and investigated the mechanical characteristics, including uniaxial compressive strength, splitting tensile strength, flexural strength, impact strength, and bond strength of concrete, and microstructural analysis, including scanning electron microscope (SEM), energy dispersive Xray spectroscopy (EDS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD), were examined. The outcome of the results revealed that the inclusion of BF and CF with alccofine improves the mechanical characteristics of concrete compared to the control mix. Compared with reference HSC, 1 % banana fiber increased the mechanical performance after 28 days of curing. BF significantly enhanced the mechanical properties of high-strength concrete compared to CF. Furthermore, banana fiber provides early warning of failure due to its elasticity. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work deals with the synthesis of biodegradable and UV resistant wood polymer composites (WPCs) via compression moulding technique. As outdoor applications become more widespread, durability becomes an issue. Ultraviolet exposure can lead to photodegradation, which results in a change in appearance and mechanical properties. In this study, we examined the performance of WPCs after UV exposure and microbial attack. The rate of degradation was found to decrease by the addition of a higher percentage of rosin derivatives. The bacterial growth on the samples and morphological features of the bacterial-degraded samples were investigated by UV spectrophotometry and Scanning Electron Microscope (SEM) study, respectively. The UV-degraded samples were also analysed by Fourier Transform Infrared (FTIR) spectroscopy and SEM study. It was observed that with the incorporation of 40 wt-% of divinylacrylicpimaric acid (DAPA) significantly improved the UV stability, mechanical, thermal and other physical properties of the WPCs. [ABSTRACT FROM AUTHOR]

SYNOPSIS: A green method to strengthen and toughen PLA by carbon dioxide (CO 2) treatment at room temperature. • Strong and ductile PLA was prepared by simple CO 2 treatment at room temperature. • CO 2 treatment induced numerous nanoscale rod-like crystallites. • CO 2 treatment led to significantly improved strength, rigidness, and toughness. • CO 2 treatment dramatically increased the Vicat softening temperature of PLA. Poly (lactic acid) (PLA) is a biodegradable and biocompatible polymer derived from renewable resources that demonstrates an immense potential in replacing fossil-based polymers. Nevertheless, its inherent brittleness and poor thermal resistance significantly restrict its further applications. Developing an environmentally friendly and cost-effective method for strengthening and toughening PLA without sacrificing its other functional properties remains a challenge. In this study, we report a novel method to reinforce PLA by carbon dioxide (CO 2) treatment at room temperature. Remarkably, CO 2 treatment led to simultaneously enhanced strength, toughness, ductility and thermal resistance. Under 3.5 MPa CO 2 treatment, PLA demonstrated the best mechanical performance with tensile strength, ductility, and impact toughness enhanced by 25%, 1214%, and 134%, respectively. Moreover, the Vicat softening temperature was significantly enhanced from 55.8 °C to 155.3 °C. Wide angle X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry elucidate the strengthening and toughening mechanism to be CO 2 -induced crystallization. The small-angle laser scattering and scanning electron microscope demonstrate the formation of numerous nanorod crystallites, which are responsible for coincidentally enhancing the strength, toughness, and thermal resistance. Thus, CO 2 treatment at room temperature provides a green and effective method to provide high-performance PLA products that have immense potential in biomedical, automotive, and other structural applications. [ABSTRACT FROM AUTHOR]

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In this paper, an attempt was made to use Prosopis juliflora fibres (PJFs) as a reinforcing agent for phenol formaldehyde (PF) composites. Mechanical properties of the composites were studied for various fibre aspect ratios (FAR) and fibre loadings (FL). A scanning electron microscope (SEM) was used to study the fractured surface of the composites. The peak range of mechanical properties was identified for composites with a FAR of 136 and fibre loading of 23.53 wt%. This study shows that the optimum FAR and fibre loading for PJFs were found to be 136 and 23.53 wt% in order to achieve good reinforcement with better mechanical properties in the PF resin matrix. Experimental results were observed to be in very good agreement with the theoretical [ABSTRACT FROM AUTHOR]

The design of underground structures such as road tunnels, railways tunnels, hydro tunnels etc. depends on the data gathered through the physical and mechanical parameters of rocks. These geotechnical parameters of rock play a significant role in the design, safety, stability and maintenance of underground structures. The rocks, when subjected to heterogeneous in-situ stress-fields created by overburden, tectonic and gravitational stresses, which is locally complicated by water pressure and stresses, persuade due to excavations. The physical and mechanical parameters play very important role in a precise forecast of rock behaviour under such inconsistent conditions. The mechanical properties of rocks change with density, porosity, variation of mineral assemblage, grain size, texture and effective pressures acting on them. Changes in physico-mechanical properties in metamorphic rocks lead to corresponding variations in failure pattern. A comprehensive study has been undertaken using three varieties of rocks obtained from the vicinity of Rohtang Tunnel in the Himalayan region. Attention has been paid to their petrographic and petrofabric analysis through scanning electron microscope (SEM) and thin sections, and physical and geotechnical properties. Various correlations between porosity, density, resistivity, sonic wave velocity in dry and saturated specimens of phyllitic and gneissic rock have been studied. Various relations have been produced between mineral compositions, porosity and density of rocks with the help of SEM and physical properties. Strength and deformation behaviour of the rocks under uniaxial compression, brazilian tension and oblique shear, in both dry and saturated states are also defined and compared with various properties. This paper highlights various relations analysed in conjunction with data on the physical and mechanical properties of metamorphic rocks. [ABSTRACT FROM AUTHOR]

In this study, the effect of microstructural modification on mechanical properties and biocorrosion resistance of pure Mg was investigated for tailoring a load-bearing orthopedic biodegradable implant material. This was performed utilizing the friction stir processing (FSP) in 1–3 passes to refine the grain size. Microstructure was examined in an optical microscope and scanning electron microscope with an electron backscatter diffraction unit. X-ray diffraction method was used to identify the texture. Mechanical properties were measured by microhardness and tensile testing. Electrochemical impedance spectroscopy was applied to evaluate corrosion behavior. The results indicate that even applying a single pass of FSP refined the grain size significantly. Increasing the number of FSP passes further refined the structure, increased the mechanical strength and intensified the dominating basal texture. The best combination of mechanical properties and corrosion resistance were achieved after three FSP passes. In this case, the yield strength was about six times higher than that of the as-cast Mg and the corrosion resistance was also improved compared to that in the as-cast condition. [ABSTRACT FROM AUTHOR]

Al–Si base composites reinforced with different mixtures of Ni and nano-Al 2 O 3 particles have been fabricated by squeeze casting and their metallurgical and mechanical characterization has been investigated. A mixture of Ni and nano-Al 2 O 3 particles of different ratios was added to the melted Al–Si piston alloy at 700 °C and stirred under pressure. After the Al-base-nano-composites were fabricated by squeeze casting, the microstructure and the particle distribution inside the matrix have been investigated using optical and scanning electron microscopes. Moreover, the hardness and the tensile properties of the resulted Al-base-nano-composites were evaluated at room temperature by using Vickers hardness and universal tensile testers, respectively. As a result, in most cases, it was found that the matrix showed a fine eutectic structure of short silicon constituent which appeared in the form of islands in the α-phase around some added particle agglomerations of the nano-composite structures. The tendency of this structure formation increases with the increase of Ni particle addition. As the ratio of the added particles increases, the tendency of these particles to be agglomerated also increases. Regarding the tensile properties of the fabricated Al-base-nano-composites, ultimate tensile strength is increased by adding the Ni and nano-Al 2 O 3 particles up to 10 and 2 wt.%, respectively. Moreover, the ductility of the fabricated composites is significantly improved by increasing the added Ni particles. The composite material reinforced with 5 wt.% Ni and 2 wt.% nano-Al 2 O 3 particles showed superior ultimate tensile strength and good ductility compared with any other added particles in this investigation. [ABSTRACT FROM AUTHOR]

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To evaluate the effect of composition, fabrication mode, and thermal cycling on the mechanical properties of different polymeric systems used for temporary dental prostheses. Standard bar-shaped specimens (25 × 2 × 2 mm) were fabricated of six polymeric systems of varying compositions and fabrication modes (n = 10/group): conventional PMMA (Alike, GC) – group CGC; conventional PMMA (Dêncor, Clássico) – group CD; bis-acryl (Tempsmart, GC) – group BGC; bis-acryl (Yprov, Yller) – group BY; milled PMMA (TelioCAD, Ivoclar) - group MI; 3D printed bis-acryl – (Cosmos Temp, Yller) group PY. Half of the specimens were subjected to 5000 thermal cycles (5 °C to 55 °C). Three-point bending tests were performed using a universal testing machine with a crosshead speed set to 0.5 mm/min. Flexural strength and elastic modulus were calculated from the collected data. FTIR spectra were recorded pre and post curing and after thermal cycling to evaluate material composition and degree of conversion. Energy-dispersive spectroscopy (EDS) and scanning electron microscope (SEM) were utilized to examine the composition and micromorphology of the systems, respectively. Data were analyzed using two-analysis of variance and Tukey tests (α = 0.05). FTIR spectra indicated that BGC, BY and PY groups corresponded to urethane dimethacrylate systems (bis-acryl), while CGC, CD, and MI groups corresponded to monomethacrylate systems, polymethyl methacrylate (PMMA). Bis-acryl BGC system yeilded the highest flexural strength (80 MPa), followed by the milled PMMA MI system (71 MPa), both statistically significant different relative to other groups. Bis-acryl BY exhibited the lowest flexural strength (27 MPa). Thermocycling significantly increased the flexural strength of all polymeric systems (∼10–15 MPa), except for the 3D-printed PY group. Bis-acryl BGC (1.89 GPa) and conventional PMMA CGC (1.66 GPa) groups exhibited the highest elastic modulus, followed by milled PMMA MI group (1.51 GPa) and conventional PMMA CD (1.45 GPa) systems, with significant difference detected between BGC group and MI and CD groups. The 3D printed PY (0.78 GPa) and bis-acryl BY (0.47 GPa) systems presented the lowest elastic modulus. Thermocycling did not have a significant influence on the elastic modulus. FTIR spectra indicate water sorption and release of unreacted monomers as well as increased degree of conversion (∼5–12%) after thermal cycling. Composition and fabrication mode and thermal cycling significantly affected the mechanical properties of polymeric systems used for temporary dental prostheses. • Composition significantly influenced the mechanical properties of temporary systems. • High inorganic content increased the mechanical properties. • Fabrication mode significantly affected the flexural strength of temporary systems. • Automixing or CAD/CAM machining resulted in more reliable temporary systems. • Thermal cycling might result in an increased degree of conversion and water sorption. [ABSTRACT FROM AUTHOR]

In order to study the effect of cadmium ions on the mechanical properties and micro-structure characteristics of the red clay in Guilin, we have conducted triaxial test and the scanning electron microscope tests to analyze the effects of cadmium ion concentration and the number of dry and wet cycles on the mechanical properties and micro-structure changes of the red clay. The results showed the effects of cadmium ions and dry-wet cycles destroy the structure of red clay. The cohesive force of red clay decreases with the increase of cadmium ion concentration, and the internal friction angle first increases and then decreases. With the rise in the number of dry and wet cycles, the cohesive force of cadmium-contaminated red clay first increases and then decreases, and the angle of internal friction rises gradually. Under the action of different cadmium ion concentrations, the stress-strain curve is strain hardening. With the concentration of cadmium ions increases, the strain hardening becomes more apparent; the peak value reached faster. and the axial strain corresponding to the peak value of the line decreases. With the increase in the number of wet and dry cycles, the volume of cadmium-contaminated red clay shrinks and its compactness increases; it gets the peak shear strength faster during the shearing process, and its peak value becomes larger and larger. The main reason for the phenomenon is that cadmium ions destroy the cementation between the particles. The soil particles are mainly in point contact which loosens the structure of the soil; on the other hand, the thickness of the surface diffusion layer of the clay particles increases through chemical action, The exchange of cations increases the porosity of the soil and weakens its strength. The dry-wet cycle shrinks the volume of the red clay, and the soil particles are mainly in surface contact; as the number of dry-wet cycles increases, the soil particles connection is closer, the soil porosity decreases and the strength increases. • Triaxial and scanning electron microscope tests are conducted. • Cadmium ion concentration effects are the analyzed. • Analyzed red clay dry & wet cycles on mechanical & micro-structure changes. • Result show cadmium ions & dry-wet cycles effect destroy the red clay structure. • Exchange of cations increases the porosity of soil and weakens its strength. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The application spectrum of low cost material reinforced metal matrix composites is growing rapidly in various engineering fields. In this way, present study indicates the possibilities of reinforcing aluminium alloy (AlSi10Mg) with locally available inexpensive rice husk ash for developing a new material. A rice husk ash particle of 3, 6, 9 & 12% by weight were used to develop metal matrix composites using a liquid metallurgy route. The surface morphology was studied using scanning electron microscope for analyze the distribution of RHA particles. The mechanical properties such as tensile strength, compressive strength, hardness and percentage elongations are studied for reinforced RHA composites. The results reveal that the percentage reinforcement of RHA will increase ultimate tensile strength, compressive strength and harness of the composite. [Copyright &y& Elsevier]

The poly(vinyl alcohol)/silica nano-composities hybrid membranes were prepared by co-hydrolysis and co-condensation of ?-glycidyloxypropyl trimethoxysilane (GPTMS) and tetraethoxysilane (TEOS) in poly(vinyl alcohol)(PVA) aqueous solution. The mechanical properties of hybrid membranes was studied, the result indicated that the well dispersion of nanoparticles was beneficial to the enhancement of the mechanical properties, and GPTMS could increase the miscibility of the polymer and SiO2. The membranes were characterized by scanning eletron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDS), 29Si CP/MAS solid-state nuclear magnatic resonance (NMR). The EDS of poly(vinyl alcohol)/silica nano-composities showed that Si element had been grafted onto the chain of PVA. The 29Si CP/MAS solid-state NMR spectra, 13C CP/MAS Solid-state NMR spectrum and EDS confirmed that silica had been introduced into the chain of PVA. Latex particle size and morphology was observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The TEM and DLS indicated that silica nanoparticles well and regularly dispersed in PVA solution and the average diameter of silica nanoparticles dispersed in PVA solution was about 58 nm. [ABSTRACT FROM AUTHOR]

Abstract: Bacterial cellulose (BC) was altered by means of 0.5-2.5% w/v diacetylglycerol in acetone-water through impregnation process provided DGBC composites. Results from the scanning electron microscope images, revealed that diacetylglycerol filled the pores of BC, leads to the significant enhanced in hydrophilicity and caused a smoother BC morphology. The addition of diacetylglycerol into BC caused a slightly changed in crystallinity indexes and bring about the reduction in tensile strength and Young''s modulus but increased in elongation at break and toughness. The significant reduction of tensile strength and Young''s modulus was achieved for DGBC 2.5% as well as for elongation at break and hydrophylicity improvement. Through the impregnation method, diacetylglycerol serves as biodegrada–ble and safe plasticizer, resulted in less rigid and higher ductility DGBC composites. [Copyright &y& Elsevier]

Annual production output of poly (ethylene terephthalate) (PET) fiber has been over 15 million tons in China due to its good mechanical properties and processability, but the shortage of hydrophilic group of PET has imposed many limitations to further extend its application. The PET fabrics were grafted with polyacrylic acid in inverse microemulsion after low pressure plasma treatment, and the microstructure and properties of the grafted fabrics were investigated with infrared spectroscopy, scanning electron microscope (SEM), hydrophilic and mechanical tests. The grafting yield was increased with the grafting time. The grafting polymer was in the granular form with its particle size ranging from a few micrometers to a dozen of micrometers, normally smaller than the fiber diameter. The moisture regain and water uptake increased while the air permeability of the grafted fabrics decreased with the increase of grafting yield. The bending rigidity and tensile properties show slightly complicated behaviors with grafting yield. The inverse emulsion grafting technique can be used to control the grafting polymer architecture. [ABSTRACT FROM AUTHOR]

Abstract: The structure and mechanical properties of the pincer exoskeletons (cuticles) of lobster (Procambarus clarkii) and crab (Eriocheir Sinensis) were investigated, respectively. The microstructures and inorganic materials of the pincer exoskeletons were observed and determined using a scanning electron microscope and X-ray diffraction. The mechanical properties of the pincer exoskeletons were evaluated by nano-indentation tests and tensile tests under different conditions. The results showed that the inorganic materials in the lobster claw exoskeleton exhibited an amorphous structure, while those in the crab claw exoskeleton were crystallized as calcium carbonate with a calcite crystal structure and were stable at the temperature below 250 °C. The surfaces of the pincers were biologically unsmooth. Many concave valleys with setae near the tip and many convex domes far off the tip were observed on the surface of the lobster pincer, while many micro-spines were seen on the surface of crab pincer. The microstructures of the pincer exoskeleton exhibited highly mineralized chitin–protein fibers arranged in a twisted plywood structure. The surface hardness and elastic modulus of the crab claws were 0.33 GPa and 8.18 GPa, respectively, higher than those of the lobster claw (0.27 and 5.44 GPa). The transition in the mechanical properties and structure between the exocuticle and the endocuticle was discontinuity. The tensile strength of the crab pincer was two times higher than that of the lobster pincer, and the dry specimen was fractured more easily than the fresh specimen. [Copyright &y& Elsevier]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To research the relationship between epoxy and fiber inherent property and mechanical properties of composite, we prepared a series of composites using three kinds of high mechanical performance epoxy resins as matrices and reinforced by the same volume fraction (5%) of short carbon and glass fiber. Their mechanical properties were investigated from the perspective of chemical structure and volume shrinkage ratio of epoxy. We analyzed their tensile strength and modulus based on the mixing rule and Halpin-Tsai equation, respectively, and studied the morphology of impact test samples by scanning electron microscope. The results show that chemical bonds formed between matrix and fiber are the most important factor to improve the mechanical properties of composite. High volume shrinkage ratio is also helpful when the fiber surface was coarse. Otherwise, the tensile strength is more sensitive to interface than the tensile modulus. It is concluded that the mechanical properties of composite are strongly affected by the chemical structure of epoxy resin, the volume shrinkage ratio of cured matrices, and properties of fiber surface. [ABSTRACT FROM AUTHOR]

To characterize the effects of aging on the nanomechanical properties and 3D surface topographical parameters of an experimental Zirconia Toughened Alumina (ZTA) composite compared to its respective individual counterpart materials. Disk-shaped specimens comprised of three material groups were processed: 1) ZTA 70/30 (70% alumina reinforced with 30% second-generation 3Y-TZP); 2) Zpex (Second-generation 3Y-TZP), and; 3) Al 2 O 3 (High purity Alumina) (n = 10/material, 12 × 1 mm). After synthesis, ceramic powders were pressed, the green-body samples were sintered and polished. Nanoindentation testing was performed to record elastic modulus (E) and hardness (H). Interferometry was utilized to assess 3D surface roughness parameters (S a , S q), while X-ray diffraction (XRD) and scanning electron microscope (SEM) assessed the crystalline content and microstructure. All tests were performed before and after simulated aging (134°C, 2.2 bar, 20 h). Statistical analyses were performed using linear mixed-model and least square difference pos-hoc tests (α = 5%). XRD spectra indicated increase of monoclinic peaks for Zpex (~18%) relative to ZTA 70/30 (~2.5%) after aging. Additionally, aging did not affect the surface roughness parameters of ZTA 70/30 and Al 2 O 3 , although a significant increase in S a was recorded for Zpex following aging (~90 nm) (p < 0.001). Al 2 O 3 yielded the highest H and E values (H:21 GPa, E: 254 GPa), followed by ZTA 70/30 (H: 13 GPa, E: 214 GPa) and Zpex (H:11 GPa, E: 167 GPa), all significantly different (p < 0.03). ZTA 70/30 and Al 2 O 3 presented high hydrothermal stability with respect to all evaluated variables, where artificial aging significantly increased the monoclinic content and surface roughness of Zpex. [ABSTRACT FROM AUTHOR]

Rubber toughened polyamide 6/polypropylene (PA6/PP) nanocomposites containing 4wt% of organophilic modified montmorilonite (OMMT) were produced by melt compounding followed by injection moulding. Four different types of elastomer were incorporated into the blends as a toughener, i.e.. ethylene-octene elastorner (POE). ethylene-propylene elastomer (EPR), maleated POE (POEgMAH) and maleated EPR (EPRgMAH). The influences of maleating on the interlacial adhesion and mechanical properties of the nanocomposites were investigated in term of mechanical testing, the X-ray diffraction (XRD) and scanning electron microscope (SEM) observation. The results showed that modulus and strength of the nanocomposites was not significantly attracted by types of elastomer and their functionality. However, the toughness of the nanocomposites toughened by maleated elastomer was higher than the unmaleated elastomer. The SEM observation revealed that rubber functionality reduces the elastomer particle size in the PA6/PP matrix due to the in situ formation of graft copolymer between maleated elastomer and PA6 during melt processing. XRD revealed that the type of elastomer and functionality did not affect the dispersion of the arganoclay in the system. [ABSTRACT FROM AUTHOR]

To measure polishability of occlusal splint materials manufactured by various methods. Seven occlusal splint materials manufactured by four different methods – Heat cured (Vertex Rapid simplified Clear), CAD-milled (Ceramill a-splint), Vacuum-formed (Proform splint) and 3D-printed (Freeprint Ortho, KeySplint Soft, DentaClear and FreePrint Splint 2.0) were tested for gloss, roughness, and surface hardness and elastic modulus. For all groups, the tests were repeated with the materials polished with three different polishing burs, pumice and high shine. All polishing procedures were standardised by applying the force of 1 N for 1 min at the set speed. 3D printed materials were further tested with additional specimens manufactured at different printing angles of 0°, 45° and 90°. Data was statistically analysed using ANOVA (SPSS Version 26) and MatLab (R2020a). Polished surfaces of each specimen were analysed under scanning electron microscope. Vacuum-formed materials showed the highest polishability (80.61 ± 0.98 GU) with no statistical significance to heat-cured or CAD-milled (p = 1.00). Pumice and high shine polish significantly improved the gloss for all groups. The mean gloss and surface roughness for all 3D-printed materials ranged from 75.24 ± 25.05 GU to 0.18 ± 0.21 GU and 2.73 ± 3.18 μ m to 0.06 ± 0.01 μ m, which was significantly lower (p < 0.001) than heat-cured, CAD-milled and vacuum-formed materials. The highest hardness (0.40 ± 0.009 GPa), elastic modulus (6.06 ± 1.49 GPa) and gloss were found when materials were 3D-printed at 45°, with the lowest surface roughness. Statistically significant differences in polishability were found among the different occlusal splint materials. The polishability and surface hardness of 3D-printed occlusal splint materials was influenced by the print angle. The 0° 3D-printed occlusal splint materials produced the highest gloss and the lowest surface roughness pre-polished, indicating that no polishing is required. While the 3D-printed occlusal splint materials at 45oand 90° required polishing with burs, pumice and high shine to reduce the surface roughness, there were layering structures created during printing. [ABSTRACT FROM AUTHOR]

To synthesize a zirconia-toughened alumina (ZTA) composite with 85% alumina matrix reinforced by 15% zirconia and to characterize its optical and mechanical properties before and after artificial aging, to be compared with a conventional dental zirconia (3Y-TZP). After syntheses, ZTA and 3Y-TZP powders were uniaxially and isostatically pressed. Green-body samples were sintered and polished to obtain 80 disc-shaped specimens per group (12 × 1 mm, ISO 6872:2015). The crystalline content and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Optical properties were determined by the calculation of contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength test (BFS). All analyses were conducted before and after artificial aging (20h, 134 °C, 0.22 MPa). Optical parameters and microhardness differences were evaluated through repeated-measures analysis of variance (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI). The synthesis of the experimental ZTA composite was successful, with 98% of theoretical density, as shown in the SEM images. XRD patterns revealed typical zirconia and alumina crystalline phases. ZTA optical properties parameters showed no effect of aging, with a high CR and low TP values denoting a high masking-ability. 3Y-TZP presented lower masking-ability and aging significantly affected its optical properties. ZTA Vickers hardness, fracture toughness and Weibull parameters, including characteristic stress and Weibull modulus were not influenced by aging, while 3Y-TZP presented a significant decrease in characteristic stress and increase in fracture toughness after aging. The ZTA probability of survival for missions of 300 and 500 MPa was estimated at ~99% validating its use for 3-unit posterior fixed dental prostheses (FDP), and no different from conventional 3Y-TZP. At high-stress mission (800 MPa) a significant decrease in probability of survival was observed for aged 3Y-TZP (84%) and for immediate and aged ZTA (73 and 82% respectively). The ZTA composite presented a dense microstructure, with preservation of the crystalline content, optical and mechanical properties after artificial aging, which encourages future research to validate its potential use for large span FDP. [ABSTRACT FROM AUTHOR]

Biodegradable electrospun nanofibrous scaffolds for bone tissue engineering applications have been extensively studied as they can provide attractive open-worked architecture resembling natural extracellular matrix, with tunable physical and mechanical properties enhancing positive cellular response. For this purpose, electrospun mats were tested in terms of morphology, mechanical and physical properties, degradation kinetics and related phenomena occurring in micro- and nanoscale. However, detailed description of internal nanostructures of electrospun mats and their changes related to in vitro degradation is still missing. In this manuscript, we report qualitative and quantitative evaluation of internal lamellar nanostructure of electrospun fibrous scaffolds made of pristine polycaprolactone and composite with polymeric matrix and nanoceramic (hydroxyapatite) filler during in vitro degradation. Morphological and mechanical studies performed with an atomic force microscope were followed by scanning electron microscope imaging and X-Ray diffraction. The results suggest degradation-dependent alteration of both organization and thickness of nano-scaled lamellas recorded with atomic force microscope. Moreover, changes of the material's internal structure were followed by enhanced stiffness and higher crystallinity of electrospun fibers. [ABSTRACT FROM AUTHOR]