Materials Literature
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In order to describe the thermomechanical properties in shape memory polymer of polyurethane series, a thermomechanical constitutive model was developed. In order to describe the variation in mechanical properties due to the glass transition, coefficients in the model were expressed by a single exponential function of…
On the basis of group theoretical symmetry criteria, the primary and secondary order parameters (OP's) have been identified for the three ferroelastic martensitic transformations that occur in the Au-Cd binary, and in the Ti-Ni-M (M = Fe, At, Cu) pseudo-binary shape-memory alloys, viz (i) from the cubic β 2 austenite…
Degree of the shape memory effect was measured either by bending, tensile and compression tests in the temperature range 77∼300 K. The yield stress increased substantially by the grain size refinement, yet maintaining a good shape memory effect. In addition to usual mentioned slow strain rate tests ( about 10 -3 s -1…
An effect of aging on shape memory behavior was investigated for Mn - 15 at.% Cu alloy. It was revealed that aging of the alloy at 693 K significantly improves both shape memory effect (SME) and reversible shape memory effect (RSME). The reason of improved SME can be attributed to the decrease in the axial ratio, c/a,…
A new model for solute redistribution in cellular or dendritic growth is presented The mass balance is an integral part of the analysis. A definition of the coefficient of redistribution extent within the solid is formulated on the basis of the description of equilibrium crystal growth. A definition of the coefficient…
Morphology and crystallography of twins in the martensite in Ti-Ni and Ti-Pd shape memory alloys are reviewed on the basis of recent electron microscopy observations. It has been confirmed that there are five and three twinning modes in Ti-Ni and Ti-Pd martensites, respectively. The morphology and crystallography of n…
Shape Memory Alloys (SMAs) have become increasingly attractive as embedded actuators in polymers yielding adaptive composite structures. In particular, SMA-elements have been used to actively or passively control shape, elastic modules, internal stress level and damping capacity of such smart composites. In the passiv…
The effect of Ta addition on the microstructure, phase transformation temperature and mechanical properties of Ni 50 Ti 50-x Ta x alloys have been studied in this paper. Beginning with a base composition of Ti 50 Ni 50 , Ti was substituted by Ta up to 15at%. A DSC, an optical microscope and SEM were used to characteri…
The purpose of this study was to determine the hemolytic potentials of discrete bubble cavitation and attached cavitation. To generate controlled cavitation events, a venturigeometry hydrodynamic device, called a Cavitation Susceptibility Meter (CSM), was constructed. A comparison between the hemolytic potential of di…
The thermal cyclic characteristics under load were investigated in a Ti 50.6 Pd 30 Ni 19.4 alloy. It is shown that the M s temperature, transformation strain and total plastic strain increase with increasing the number of the cycles and the increments increase with an increase of applied stress. All the above changes…
High-resolution electron microscopy study has been made on the trained sample of an Fe-14Mn-6Si-9Cr-5Ni (mass %) alloy in order to know the mechanism of improvement of shape memory effect. High densities of extremely thin hcp martensite plates with uniform distribution are produced by training, which is regarded as th…
High-temperature shape memory effect (HTSME) takes place in different alloys and compounds, such as: TiNi with Pt, Pd, Zr and Hf additions, Zr-based quasibinary intermetallics, NiAl-based, Cu-Al-Mn, Cu-Al-Zn and Fe-Ni-Co-Ti. It can be presumably adopted that all materials exhibit SME higher than 200°C should be consid…
The reason for the strong composition and heat-treatment dependence- of the martensitic transformation temperature was investigated by a simple Landau-type model. Assuming the anharmonic and coupling coefficients are insensitive to composition, we obtained an important result martensitic transformation occurs at a cri…
Liquid-crystalline physical gels have been obtained by the self-aggregation of a gluconamide derivative through intermolecular hydrogen bonding in liquid crystals. These liquid-crystalline gels are microphase-separated composites consisting of the solid fibrous aggregates of the gelling agent and the liquid-crystallin…
[reaction: see text] A convenient synthesis of monodendrons whose conformation is restricted through the intervention of intramolecular hydrogen bonding and repulsive electrostatic interactions is described. X-ray crystal structure analysis of the second generation dendron shows the presence of a propeller-type second…
[structure: see text] Experimental and calculated data show that the relative energy levels of the two lowest excited states of azulene are sensitive to the nature and position of substituents on the nonalternant hydrocarbon. Extending such investigations led to a rational explanation for some of the baffling data on…
The contact angles of soft latex dipped films of high-ammonia natural rubber (HA) latex concentrate, deproteinized natural rubber (DPNR) latex, and oil-incorporated natural rubber latex were determined by the sessile drop method. The surface free energies were calculated using different procedures available in the lit…
The influence of droplet size and Ostwald ripening on the dynamic shear rheology of 25 wt % hydrocarbon oil-in-water emulsions containing small droplets (75 to 100 nm) stabilized by sodium dodecyl sulfate (SDS) was measured. Emulsions underwent a liquid-to-solid transition when the mean droplet radius was decreased be…
One of the most important applications of the Knudsen cell reactor is in determining heterogeneous reaction kinetics of potentially important atmospheric reactions. Knudsen cell measurements involving gas reactions on atmospherically relevant particle surfaces, including salt, carbon black, soot, and mineral dust, are…
The reaction pathways and the energetics for the direct methane−methanol and benzene−phenol conversions that occur on the surface of Fe−ZSM-5 zeolite are analyzed from B3LYP DFT computations. We propose a reasonable model for “α-oxygen”, a surface oxygen species responsible for the catalytic reactivities of Fe−ZSM-5 z…