Materials Literature
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High-resolution neutron diffraction results for KH 2 PO 4 (KDP) and its deuterated form (DKDP) have been used to re-examine evidence that the large increase in the phase transition temperature, T c , on deuteration can be explained simply by the increase in the phase transition temperature, T c , on deuteration can be…
We demonstrate the relation $\ensuremath{\theta}=2\ensuremath{\varphi}$. Here the exponent $\ensuremath{\theta}$ is defined as $D\ensuremath{\sim}{N}^{\ensuremath{\theta}}$, where $D$ is the equilibrium lamellar thickness of the diblock copolymer ordered phase and $N$ is the molecular weight. The exponent $\ensuremath…
A 1D quasicrystal derived from the 2D decagonal quasicrystal has been found in rapidly solidified ${\mathrm{Al}}_{80}$${\mathrm{Ni}}_{14}$${\mathrm{Si}}_{6}$, ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Mn}}_{15}$, and ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Co}}_{15}$ alloys. They inherit periodicity…
We show that pairs of simple energy bands exist that have identical symmetries for their Bloch functions, but different symmetries for the corresponding Wannier functions. For finite crystals such pairs of bands belong to equivalent band representations. In the case of infinite crystals, we use the analyticity of simp…
The temperature dependence of the dc conductivity has been measured on sputtered amorphous carbon films. The conductivity is proportional to ${T}^{n}$ with $n=15\ensuremath{-}17$ over a wide temperature range, suggesting for the first time that the multiphonon tunneling transition with weak electron-lattice coupling o…
Suspensions in a liquid of "nearly hard" colloidal spheres were subjected to steady and oscillatory shear flows and studied by light scattering. Samples which exhibit a fluidlike ordering of the particles in equilibrium were induced to a solidlike order by oscillatory shear of strain amplitude \ensuremath{\simeq}1. In…
Abstract Dried gel film of ultrahigh‐molecular‐weight polyethylene (UHMW PE) can be drawn to 370 times its original length at 135°C. Single‐crystal mats and dried gel film of UHMW PE develop double orientation despite uniaxial stretching. This is unique for preferentially oriented UHMW PE systems. To elucidate the ori…
Abstract In Part II of this series we reported that by using a successively stretching tenter method, biaxially‐oriented polypropylene films (BOPs) with a crater‐like roughness have been obtained by selecting appropriate machine direction (MD) stretching conditions. In the present article, in order to select still bet…
The crystallographic structure of a large class of ABX 3 compounds can be characterised by the stacking sequences of face- and corner-sharing BX 6 -octahedra chains on a hexagonal lattice. Many different polytypes described by this type of stacking have been observed in these and related materials. An axial Ising-type…
Abstract Thermal degradation of polychloroprene under nitrogen, especially at the initial stages, has been studied by using 1 H‐NMR, 13 C‐NMR and FT–IR spectroscopy. A model polymer of low molecular weight ( M n = 6300) was prepared to avoid gelation during degradation. None of isomerized 1,2 unit has been found in th…
Abstract Sheets were cast by extruding polypropylenes (PP) which contained γ‐quinacridone, a β‐crystal nucleator, at levels of 0–10 ppm using a 30 mm ϕ extruder with a T‐die at extrusion temperatures of 200–260°C and chill roll temperatures of 30–90°C. The influences of raw resin characteristics such as γ‐quinacridone…
Abstract Solvent extraction followed by DSC, optical microscopy, and transmission electron microscopy show morphological evidence of molecular segregation for binary mixtures of poly(ethylene oxide)s (PEO). Two segregation types, namely microscopic and macroscopic segregation, have been found. A special etching method…
Abstract Polystyrene was crosslinked in either 1,2‐dichloroethane or carbon tetrachloride in the presence of aluminum chloride. Apparently, the reactions involve Friedel–Crafts substitution of phenyl ring with CH 2 CH 2 Cl or CCl 3 groups, which than participate in crosslinking, giving CH 2 CH 2 or CCl 2 , CCl, and C…
Abstract The glass transition temperature T g of propylene glycol (PG) and poly(propylene glycols) (PPGs) of molecular weight up to 4000 has been measured by differential scanning calorimetry, and the activation energy and change in heat capacity Δ C p have been determined in the glass transition range. The activation…
Abstract Differential scanning calorimetry (DSC) has been used to study the crystallization kinetics and thermal characteristics of poly(aryl‐ether–ether‐ketone) (PEEK) samples heated under a variety of conditions. Samples were heated in nitrogen and air at temperatures between 380 and 420°C for times up to 120 min. T…
Abstract The fracture toughness of commercial linear low‐density polyethylenes (LLDPE) has been found to be extraordinarily high relative to commercial low‐density (LDPE) and high‐density (HDPE) polyethylenes in previously reported investigations. The present investigation shows that this extraordinary fracture toughn…
It has now been established that paracrystals are the 'building blocks' of many materials including polymers, biological materials, colloids, molten metals and alloys, and catalysts. The concept of paracrystallinity and the main equations which are needed for the practical application of the theory to X-ray, neutron a…
For the N-V centre in type Ib diamond the optical detection of spin coherence in the 3 A state is reported. The 3 A-state lifetime is studied as a function of the light intensity used for the optical excitation of the N-V centre by means of spin-locking experiments. The shortening of the lifetime at higher excitation…
Diamond may be grown at low pressures where it is the metastable form of carbon. Recent advances in a wide variety of plasma and electrical discharge methods have led to dramatic increases in growth rates. All of these methods have certain aspects in common, namely, the presence of atomic hydrogen and the production o…
Luminescence measurements (photo-, X-ray-induced and thermo-), ionic thermocurrent and optical absorption data are presented on CaF2 doped with Ce and with Mn. The purpose of the study is to examine the processes of energy storage in this material following irradiation, and the subsequent release of this energy in the…