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fracture toughness

Salvatore Sauro, Ashvin Babbar, Borzo Gharibi, Victor Pinheiro Feitosa, Ricardo Marins Carvalho, Lidiany Karla Azevedo Rodrigues, Avijit Banerjee, Timothy Watson
OBJECTIVE: Materials for pulp protection should have therapeutic properties in order to stimulate remineralization and pulp reparative processes. The aim of this study was to evaluate the mechanical properties, biocompatibility, cell differentiation and bioactivity of experimental light-curable resin-based materials containing bioactive micro-fillers. METHODS: Four calcium-phosphosilicate micro-fillers were prepared and incorporated into a resin blend: 1) Bioglass 45S5 (BAG); 2) zinc-doped bioglass (BAG-Zn); 3) βTCP-modified calcium silicate (β-CS); 4) zinc-doped β-CS (β-CS-Zn)...
March 16, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
Sufyan Garoushi, Pekka K Vallittu, Lippo Lassila
This study investigated the reinforcing effect of discontinuous-glass fiber fillers with different loading-fractions on selected mechanical properties and wear of resin-modified glass ionomer cement (RMGIC). Experimental fiber-reinforced RMGIC (Exp-RMGIC) was prepared by adding discontinuous-glass fiber of 200-500 µm in length to the powder of RMGIC (GC Fuji II LC) with different weight ratios (15, 20, 25 and 30 wt%). Mechanical properties and wear were determined for each experimental and control material...
March 17, 2018: Dental Materials Journal
Jingwei He, Sufyan Garoushi, Pekka K Vallittu, Lippo Lassila
This study was conducted to determine whether novel experimental low-shrinkage dimethacrylate co-monomers could provide low polymerization shrinkage composites without sacrifice to degree of conversion, and mechanical properties of the composites. Experimental composites were prepared by mixing 28.6 wt% of bisphenol-A-glycidyl dimethacrylate based resin matrix ( bis -GMA) with various weight-fractions of co-monomers; tricyclo decanedimethanol dacrylate (SR833s) and isobornyl acrylate (IBOA) to 71.4 wt% of particulate-fillers...
2018: Acta Biomaterialia Odontologica Scandinavica
Riku Takahashi, Tao Lin Sun, Yoshiyuki Saruwatari, Takayuki Kurokawa, Daniel R King, Jian Ping Gong
Reinforcing hydrogels with a rigid scaffold is a promising method to greatly expand the mechanical and physical properties of hydrogels. One of the challenges of creating hydrogel composites is the significant stress that occurs due to swelling mismatch between the water-swollen hydrogel matrix and the rigid skeleton in aqueous media. This stress can cause physical deformation (wrinkling, buckling, or fracture), preventing the fabrication of robust composites. Here, a simple yet versatile method is introduced to create "macroscale" hydrogel composites, by utilizing a rigid reinforcing phase that can relieve stress-induced deformation...
March 13, 2018: Advanced Materials
T J A G Münker, S E C M van de Vijfeijken, C S Mulder, V Vespasiano, A G Becking, C J Kleverlaan, A G Becking, L Dubois, L H E Karssemakers, D M J Milstein, S E C M van de Vijfeijken, P R A M Depauw, F W A Hoefnagels, W P Vandertop, C J Kleverlaan, T J A G Münker, T J J Maal, E Nout, M Riool, S A J Zaat
BACKGROUND: Nowadays, personalized medical devices are frequently used for patients. Due to the manufacturing procedure sterilization is required. How different sterilization methods affect the mechanical behavior of these devices is largely unknown. MATERIALS AND METHODS: Three poly(methyl methacrylate) (PMMA) based materials (Vertex Self-Curing, Palacos R+G, and NextDent C&B MFH) were sterilized with different sterilization methods: ethylene oxide, hydrogen peroxide gas plasma, autoclavation, and γ-irradiation...
January 31, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Bingbing An, Dongsheng Zhang
Dentin is a biocomposite possessing complex hierarchical structure, which endows this hard tissue with excellent damage tolerance. In this study, crack growth in dentin at the microstructural scale is investigated and the synergistic effects of plastic deformation of intertubular dentin (ITD), elasticity and fracture properties of peritubular dentin (PTD), and fracture properties of PTD/ITD interface on the fracture of dentin are explored. A micromechanical model is developed, which captures the experimentally observed fracture process of dentin, i...
February 26, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Otto Steinmassl, Vincent Offermanns, Wolfgang Stöckl, Herbert Dumfahrt, Ingrid Grunert, Patricia-Anca Steinmassl
Computer-aided design and computer-aided manufacturing (CAD/CAM) denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than conventional, manually fabricated dentures. The aim of this study was to investigate if commercially available CAD/CAM denture base resins have more favourable mechanical properties than conventionally processed denture base resins...
March 8, 2018: Materials
Xiaolei Ren, Kostiantyn Turcheniuk, Daniel Lewis, Wenbin Fu, Alexandre Magasinski, Mark W Schauer, Gleb Yushin
Conventional slurry casted electrodes cannot stand high loads or be repeatedly flexed or bent without being fractured, which inhibits their use in flexible batteries. Carbon nanotube (CNT) fabric exhibits a paramount mechanical stability and, due to its porosity, can additionally accommodate an active material within its structure. While solution-based protocols cannot achieve conformal coatings of active materials, chemical vapor deposition (CVD) gives a unique opportunity to control and vary the thickness and homogeneity of the coating...
March 2, 2018: Small
Hila Shalom, Yishay Feldman, Rita Rosentsveig, Iddo Pinkas, Ifat Kaplan-Ashiri, Alexey Moshkovich, Vladislav Perfilyev, Lev Rapoport, Reshef Tenne
Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS₂ (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase...
February 26, 2018: International Journal of Molecular Sciences
Daniela Astudillo-Rubio, Andrés Delgado-Gaete, Carlos Bellot-Arcís, José María Montiel-Company, Agustín Pascual-Moscardó, José Manuel Almerich-Silla
Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians' criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness...
2018: PloS One
Emil Sandoz-Rosado, Todd D Beaudet, Jan W Andzelm, Eric D Wetzel
The linear polymer poly(p-phenylene terephthalamide), better known by its tradename Kevlar, is an icon of modern materials science due to its remarkable strength, stiffness, and environmental resistance. Here, we propose a new two-dimensional (2D) polymer, "graphamid", that closely resembles Kevlar in chemical structure, but is mechanically advantaged by virtue of its 2D structure. Using atomistic calculations, we show that graphamid comprises covalently-bonded sheets bridged by a high population of strong intermolecular hydrogen bonds...
February 27, 2018: Scientific Reports
S Cavelier, A K Dastjerdi, M D McKee, F Barthelat
The most prominent structural components in bone are collagen and mineral. However, bone additionally contains a substantial amount of noncollagenous proteins (most notably of the SIBLING protein family), some of which may act as cohesive/adhesive "binders" for the composite hybrid collagen/mineral scaffolding, whether in the bulk phase of bone, or at its interfaces. One such noncollagenous protein - osteopontin (OPN) - appears to be critical to the deformability and fracture toughness of bone. In the present study, we used a reconstructed synthetic mineral-OPN-mineral interface, and a biogenic (natural tooth dentin) mineral/collagen-OPN-mineral/collagen interface, to measure the fracture toughness of OPN on mineralized substrates...
February 24, 2018: Bone
Zhenzhen Zhang, Jiawen Guo, Yali Sun, Beimin Tian, Xiaojuan Zheng, Ming Zhou, Lin He, Shaofeng Zhang
OBJECTIVES: The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. METHODS: After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment...
February 20, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Jian-Tao Liu, Feng Zhang, Zheng-Chao Gao, Bin-Bin Niu, Yu-Huan Li, Xi-Jing He
Artificial vertebral body has achieved good results in treating spinal tumors, tuberculosis, fracture and other diseases. Currently, artificial vertebral body with variety of kinds and pros and cons, is generally divided into two types: fusion type and movable type. The former according to whether the height could be adjusted and strength of self-stability is divided into three types: support-fixed type, adjust-fixed type and self-fixed type. Whether the height of self-fixed type could be adjusted is dependent on structure of collar thread rotation...
December 25, 2017: Zhongguo Gu Shang, China Journal of Orthopaedics and Traumatology
Gyubaek An, Se-Min Jeong, Jeongung Park
Brittle failure of high toughness steel structures tends to occur after ductile crack initiation/propagation. Damages to steel structures were reported in the Hanshin Great Earthquake. Several brittle failures were observed in beam-to-column connection zones with geometrical discontinuity. It is widely known that triaxial stresses accelerate the ductile fracture of steels. The study examined the effects of geometrical heterogeneity and strength mismatches (both of which elevate plastic constraints due to heterogeneous plastic straining) and loading rate on critical conditions initiating ductile fracture...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Young-Chul Park, Chang-Been Lee, Seong-Sik Bang, Dong-Ki Choi, Woo-Sik Whang, Jae-Kwon Lee, Jung-Woo Han, Taek-Kyun Jung
WC based alloy coatings included different mass percent of Co and Cr have been synthesized on high carbon steel by using a facile high velocity oxy-fuel spray method. The mechanical nature of the coating films has been investigated by micro vickers hardness and fracture toughness. X-ray diffraction (XRD) and EDX analyses indicate that the three different samples (WC-10Co-4Cr, WC-17Co, and WC-12Co) consist of pure WC, W, Cr, and Co constituents as well as W2C and Co6W6C phases. The SEM and image analysis results show that WC-10Co-4Cr condition has higher porosity than those of WC-17Co, and WC-12Co coatings...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Seong-Sik Bang, Young-Chul Park, Ji-Woon Lee, Soong-Keun Hyun, Tae-Bum Kim, Jae-Kwon Lee, Jung-Woo Han, Taek-Kyun Jung
In this study influence of spray distance on the properties of WC-12Co coatings deposited by HVOF was investigated. WC-12Co coating was sprayed at spray distance of 300, 385 and 450 mm. From microstructure observation, it is confirmed that the porosity of coatings increases with increasing the spray distance. The X-ray diffraction patterns indicate that the coatings consist of pure WC, W, and Co as well as W2C and Co6W6C phases. The increase of the spray distance accelerated the decarburization of coatings...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Young-Gon Kim, Kuk-Hyun Song, Dong-Hoon Lee, Sung-Min Joo
The demand of crack tip opening displacement (CTOD) test which evaluates fracture toughness of a cracked material is very important to ensure the stability of structure under severe service environment. The validity of the CTOD test result is judged using several criterions of the specification standards. One of them is the artificially generated fatigue pre-crack length inside the specimen. For acceptable CTOD test results, fatigue pre-crack must have a reasonable sharp crack front. The propagation of fatigue crack started from the tip of the machined notch, which might have propagated irregularly due to residual stress field...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Zhao Jing Ming, Jong Kook Lee, Hwang Kyu Hong, Jang Jeong Ho
Nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase was prepared using ethylene diamine (EDA), which acts as both precipitating agent and dispersant of the zirconium precursor. The yttria stabilized zirconia (Y-TZP) is a very attractive material due to its excellent biocompatibility, high fracture toughness, high strength and low wear rates. So zirconyl chloride octahydrate (ZrOCl2 · 8H2O) and yttrium chloride hexahydrate (YCl3 · 6H2O) in different molar ratios were used as starting solution...
February 1, 2018: Journal of Nanoscience and Nanotechnology
Tiankai Yao, Guoqing Xin, Spencer Michael Scott, Bowen Gong, Jie Lian
Low thermal transport behavior along the radial direction of nuclear fuel pellets and pellet-cladding mechanical interaction significantly impact fuel performance and the safety of current nuclear energy systems. Here we report a new strategy of advanced fuel design in which highly thermally-conductive and mechanically-robust graphene nanoplatelets are incorporated into UO 2 fuel matrix to improve fuel thermal-mechanical properties. The 2D geometry of the graphene nanoplatelets enables a unique lamellar structure upon fuel consolidation by spark plasma sintering...
February 14, 2018: Scientific Reports
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