Materials Literature
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Abstract Isotactic (i) and syndiotactic (s) PMMA polymers differ markedly in the physical properties. The fact that these physically unlike macromolecules strongly attract each other with the resultant formation of stereocomplexes is indeed remarkable. Although stereoregular PMMAs and the stereocomplex have been studi…
Abstract It is widely accepted that for the very smallest grain sizes (typically below 20 – 30 nm), dislocations play no significant role in the deformation of nanocrystalline materials. However, the grain-boundary mechanisms responsible for the reported decrease in strength with decreasing grain size in this regime (…
Abstract The current research on grain boundary dynamics in metals is reviewed. The boundary dynamics, i. e., the boundary reaction to applied forces, is strongly dependent on the grain boundary character, which is commonly reduced to the orientation relationship between adjacent grains and impurity segregation at the…
The use of shape memory alloys in spacecraft and devices was suggested practically as soon as the first materials of this type had been discovered and investigations of their unique functional and mechanical properties had begun. However, various reasons led to a more than 30-years delay in realization of ideas in dev…
Martensitic transformations in commercial near equiatomic Ni49.5Ti (at. %) polycrystalline thick wires induced by thermal and/or mechanical loading were investigated by in-situ high-resolution neutron powder diffraction techniques with the aim to develop neutron diffraction methods of stress and phases fraction evalua…
Abstract The crystal structure of biotite-1 M from Bancroft, Ontario, with the formula: <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/…
Abstract. The usual process to produce NiTi shape memory alloy is by vacuum induction melting (VIM) using a graphite crucible, which causes contamination of the melt with carbon. Contamination with oxygen originates from the residual oxygen inside the melting chamber. An alternative process to produce NiTi alloys is b…
Amorphous ribbons of the ternary shape memory alloy Ti 50 Ni 25 Cu 25 crystallize polymorphously upon heating. The subsequent growth proceeds isotropic resulting in the formation of perfectly spherical grains in an amorphous matrix at intermediate stages of the transformation. These experimental results match exactly…
A new type of 110-kV and 220-kV whole-solid-insulation polymeric ZnO surge arresters is developed. The power loss characteristics of ZnO varistors are discussed, which are simulated by an artificial neural network (ANN) model. The thermal performances of the new developed polymeric arresters are analyzed by the finite…
The crystal structure of orthorhombic martensite in ternary TiNi-based compounds has been several times examined, although, in all cases, the structure was not completely solved as the positions of atoms in the unit cell remained unknown. In the present work, the X-ray patterns of TiNi-Cu and TiNi-Pd films were refine…
The objective of this study is determining the kinetic parameters of thermal degradation of polyurethane elastomers before and after UV irradiation. To determine the kinetic parameters of elastomeric polyurethane (PUR) decomposition the Freeman-Carroll method of calculation is applied. The effect of soft segment and h…
This work combines classical continuum mechanics, the continuously dislocated continuum theory as developed by Kröner and Bilby with discrete dislocation theory to develop quantities that permit models involving interactions between individual dislocations to be incorporated into a description of multiaxial yielding o…
Electrical tuning of dispersion characteristics has been studied experimentally for hybrid surface electromagnetic-spin waves propagating perpendicularly to the direction of the static magnetization in tangentially magnetized layered structures containing ferrite and ferroelectric layers. The tuning is realized throug…
Abstract A series of poly(2‐alkyl‐6‐phenylphenylene ether)s were prepared by the oxidative polymerization of 2‐alkyl‐6‐phenylphenols. Their dielectric constants were approximately 2.5, whereas it was found that the phenyl group at the 6‐position clearly increased the Q factor of the polymer compared with poly(2,6‐dime…
Abstract Polymerization of cyclic esters leads to (bio)degradable polymers of the increasing industrial importance. These polymerizations are of the living nature, although chain transfer to polymer with chain scission may cause deviations from the livingness and introduce structural differences (e.g. in end‐groups),…
A new series of multicomponent ZnPc-Ru(bpy)(3) systems, 1a-c, consisting of a zinc-phthalocyanine linked through conjugated and/or nonconjugated connections to a ruthenium(II) tris(bipyridine) complex, has been synthesized. The ruthenium complexes 1a-c were prepared from phthalocyanines 2a-c, bearing a 4-substituted-2…
Abstract Graft copolymers of starch and polyacrylamide (PAAm) were prepared by reactive extrusion using a co‐rotating twin‐screw extruder and ammonium presulfate initiator. Feed rates were 109 g/min to 325 g/min (all components) at a moisture content of 50%, with screw speeds in the range 100 rpm to 300 rpm. Starch/ac…
Abstract Basalt fibers, similarly to other silicate fibers, can be introduced into both thermoplastic and thermosetting polymer matrices. In this work some basalt fiber reinforced polypropylene composites were investigated. The fiber‐matrix adhesion was improved by commercial and non‐commercial maleic anhydride deriva…
Abstract Phenylethynyl containing imide oligomers have been under investigation as part of an effort to develop resins for non‐autoclave composite fabrication processes such as resin transfer molding (RTM). These high performance/high temperature composites are potentially useful on advanced aerospace vehicles such as…
Pyridoxal 5'-phosphate is an essential cofactor for many enzymes responsible for the metabolic conversions of amino acids. Two pathways for its de novo synthesis are known. The pathway utilized by Escherichia coli consists of six enzymatic steps catalyzed by six different enzymes. The fourth step is catalyzed by 4-hyd…