Development and Characterization of High Performance Shape Memory Alloy Coatings for Structural Aerospace Applications.

This paper presents an innovative approach, which enables control of the mechanical properties of metallic components by external stimuli to improve the mechanical behavior of aluminum structures in aeronautical applications. The approach is based on the exploitation of the shape memory effect of novel Shape Memory Alloy (SMA) coatings deposited on metallic structural components, for the purpose of relaxing the stress of underlying structures by simple heating at field-feasible temperatures, therefore enhancing their structural integrity and increasing their stiffness and rigidity while allowing them to withstand expected loading conditions safely. Numerical analysis provided an insight in the expected response of the SMA coating and of the SMA-coated element, while the dependence of alloy composition and heat treatment on the experienced shape memory effect were investigated experimentally.

Synthesis and study of physical properties of dental light-cured nanocomposites using different amounts of a urethane dimethacrylate trialkoxysilane coupling agent.

Objective: The purpose of this work was the study of the effect of the amount of a urethane dimethacrylate silane (UDMS) coupling agent on physical properties of dental light-cured resin nanocomposites based on Bis-GMA/TEGDMA (50/50 wt/wt) matrix and Aerosil OX50 as filler.

Methods: Silica nanoparticles (Aerosil OX 50) used as filler were silanized with 5 different amounts of UDMS 1.0, 2.

Sorption of water, ethanol or ethanol/water solutions by light-cured dental dimethacrylate resins.

Objectives: This work is concerned with the study of the sorption and desorption process of water, ethanol or ethanol/water solution 50% (v/v) or 75% (v/v) by the dental resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D₃MA.

Methods: A thin resin disc is placed in a bath of time to obtain the sorption curve m(t)=f(t). Then the liquid is desorbed until a constant mass for the disc is reached and the desorption curve is recorded.

Synthesis and study of properties of dental resin composites with different nanosilica particles size.

Objectives: The aim of this work was the synthesis of light-cured resin nanocomposites using nanosilica particles with different particle size and the study of some physical-mechanical properties of the composites.

Methods: Various types of silica nanoparticles (Aerosil) with average particle size of 40, 20, 16, 14, and 7 nm, used as filler were silanized with the silane 3-methacryloxypropyl-trimethoxysilane (MPS). The total amount of silane used was kept constant at 10 wt% relative to the filler weight to ensure the complete silanization of nanoparticles.

Physical properties of current dental nanohybrid and nanofill light-cured resin composites.

Objectives: The purpose of this work was the detailed study of sorption characteristics of water or artificial saliva, the determination of flexural strength and the flexural modulus, and the study of the thermal stability of some current commercial dental light-cured nanocomposites containing nano-sized filler particles.

Methods: Three nanohydrid dental composites (Tetric EvoCeram (TEC), Grandio (GR) and Protofill-nano (PR)) and two nanofill composites (Filtek Supreme Body (FSB) and the Filtek Supreme Translucent (FST)) were used in this work. The volumetric shrinkage due to polymerization was first determined.

Physical properties of a hybrid and a nanohybrid dental light-cured resin composite.

This work was aimed at the study of some physical properties of two current light-cured dental resin composites, Rok (hybrid) and Ice (nanohydrid). As filler they both contain strontium aluminosilicate particles, however, with different size distribution, 40 nm-2.5 mum for Rok and 10 nm-1 mum for Ice.

Dynamic mechanical analysis of a hybrid and a nanohybrid light-cured dental resin composite.

This work was aimed at the study of the viscoelastic properties of two current light-cured dental resin composites, Rok (hybrid) and Ice (nanohybrid), by dynamic mechanical analysis, under the influence of variable temperatures and frequencies 1 h after curing or after storage at 37 degrees C either in air or distilled water for 1, 7 or 30 days. They both contain about the same amount of filler, which is strontium aluminosilicate particles, but they have different size distribution, 40 nm-2.5 microm for Rok and 10 nm-1 microm for Ice.

Effect of the amount of 3-methacyloxypropyltrimethoxysilane coupling agent on physical properties of dental resin nanocomposites.

Objectives: The purpose of this study was to evaluate the effect of the amount of 3-methacryloxypropyl-trimethoxysilane (gamma-MPS) coupling agent on some physical-mechanical properties of an experimental resin composite for understanding the optimum amount of silanization.

Methods: Silica nanoparticles (Aerosil OX 50) used as filler were silanized with 5 different amounts of gamma-MPS 1.0, 2.

Effect of the structure of silane coupling agent on sorption characteristics of solvents by dental resin-nanocomposites.

Objective: This work was aimed at the study of sorption characteristics of water or ethanol/water solution (75vol%/25vol%) by dental nanocomposites consisting of a Bis-GMA/TEGDMA (50/50, wt/wt) matrix and silica nanoparticles (Aerosil OX50) as filler, silanized with various silanes. The silanes used were 3-[(1,3(2)-dimethacryloyloxypropyl)-2(3)-oxycarbonylamido]propyltriethoxysilane, which is a urethane dimethacrylate silane (UDMS), 3-methacryloxypropyltrimethoxysilane (MPS), octyltrimethoxysilane (OTMS), blends UDMS/OTMS (50/50, wt/wt) or blends MPS/OTMS (50/50, wt/wt).

Methods: The composite specimens (15mm diameterx1mm height) were immersed in water or ethanol/water solution at 37+/-1 degrees C for 30 days.

Volumetric dimensional changes of dental light-cured dimethacrylate resins after sorption of water or ethanol.

Objectives: This study evaluated the influence of water and ethanol sorption on the volumetric dimensional changes of resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D(3)MA.

Methods: The resin specimens (15mm diameterx1mm height) were immersed in water or ethanol 37+/-1 degrees C for 30 days. Volumetric changes of specimens were obtained via accurate mass measurements using Archimedes principle.

Dynamic thermomechanical properties and sorption characteristics of two commercial light cured dental resin composites.

Objectives: The first objective of this work is the study by DMTA of viscoelastic properties (E', E'', tandelta, Tg) of two current dental resin composites Tetric EvoCeram (nanohybrid) and Heliomolar (microfilled) in dry condition and in water for up to 30 days. The second objective is to determine the sorption characteristics of these composites in water and ethanol/water solution 75vol.%.

Aging studies of light cured dimethacrylate-based dental resins and a resin composite in water or ethanol/water.

Objective: To study the aging of neat resins, prepared from bis-GMA, UDMA, D(3)MA or a mixture of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w), in water or 75% (v/v) ethanol/water 37 degrees C. Also the study of aging of Heliomolar RO, which is a radiopaque, microfilled, light cured composite, the resin matrix of which is the copolymer of bis-GMA/UDMA/D(3)MA (65/20/15 w/w/w).

Methods: Samples of neat resins and Heliomolar RO prepared by light curing were immersed in water or 75% (v/v) ethanol/water 37 degrees C, for 1, 7 or 30 days.

Sorption kinetics of ethanol/water solution by dimethacrylate-based dental resins and resin composites.

In the present investigation the sorption-desorption kinetics of 75 vol % ethanol/water solution by dimethacrylate-based dental resins and resin composites was studied in detail. The resins examined were made by light-curing of bisphenol A glycol dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), bisphenol A ethoxylated dimethacrylate (Bis-EMA), and mixtures of these monomers. The resin composites were prepared from two commercial light-cured restorative materials (Z100 MP and Filtek Z250), the resin matrix of which is based on copolymers of the above-mentioned monomers.