Morphology and mechanical properties in the binary blends of isotactic polypropylene and novel propylene-co-olefin random copolymers with isotactic propylene sequence 1. Ethylene-propylene copolymers

The additive effects of the novel ethylene-propylene random (EP) copolymers with high isotacticity in propylene sequence on the morphology and mechanical properties of isotactic polypropylene (iPP) were investigated using polarized optical microscopy, transmission electron microscopy, dynamic mechanical analysis and tensile behavior. According to these results, the EP copolymers with a propylene content of more than 84 mol% were miscible with iPP, in which the crystallizable PP sequences in these EP copolymers were incorporated in crystal lattice of iPP and the other portions in the EP chains were excluded to the amorphous phases. Consequently, they act as tie molecules linking between adjacent lamellae, leading to enhancement of yield toughness of iPP. On the other hand, the EP copolymers with a propylene-unit content of less than 77 mol% were incompatible with iPP. The iPP/EP blends showed the phase-separated morphology.     

Interface Reactions between Silicon Dioxide-Lead Oxide Glass and Manganese Zinc Ferrite

The interface reations between SiO₂–PbO melt and Mn-Zn ferrite were studied using electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Intermediate layers were formed at the interface between the glass and the Mn-Zn ferrite which were heated at 800° and 900°C, although those layers were not found in specimens heated at 1000°C. Using EPMA and XRD, the intermediate layers were found to be Pb₂(Mn, Fe)₂Si₂O₉ and Pb₈(Mn, Fe)Si₆O₂₁. The mechanisms of interface reactions are discussed, related to glassforming regions. It was concluded that the interface reaactions between SiO₂–PbO melt and Mn-Zn ferrite are controlled by the dissolution of Zn ions and Mn ions from the Mn-Zn ferrite.     

Solid‐state polymerization of melt‐spun poly(ethylene terephthalate) fibers and their tensile properties

The production of high modulus and high strength poly(ethylene terephthalate) fibers was examined by using commercially available melt‐spun fibers with normal molecular weight (intrinsic viscosity = 0.6 dL/g). First, molecular weight of as‐spun fibers was increased up to 2.20 dL/g by a solid‐state polymerization, keeping the original shape of as‐spun fibers. Second, the polymerized as‐spun fibers were drawn by a conventional tensile drawing. The achieved tensile modulus and strength of as‐drawn fibers (without heat setting) were 20.0 and 1.1 GPa, respectively. A heat setting was carried out for the as‐drawn fibers. Tensile properties of the treated fibers were greatly affected by the condition of the heat setting. This was related to the increase of sample crystallinity and molecular degradation during the treatments. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1791–1797, 2007     

Comparing microscopic with macroscopic elastic properties of polymer gel

Measurements of the local elastic modulus of agar gels obtained with atomic force microscope (AFM) force mapping were compared with values obtained by the tensile creep method. The observed spatial distributions of the local elastic modulus over the gel surface in AFM elastic images clearly corresponded to the network structure of agar fibers observed both in AFM topographic and scanning electron microscope (SEM) images. Both peak and average values of distribution functions in the histograms of local elastic modulus increase monotonically with the agar concentration. Values obtained by AFM force mapping were found to be proportional to values obtained from creep experiments.     

Energetics of three-state unfolding of a protein: canine milk lysozyme

Thermodynamics of thermal transitions of a calcium-binding lysozyme,canine milk lysozyme (CML), was studied using differential scanningcalorimetry and compared with those for homologous proteins,human     

Calorimetric study of mutant human lysozymes with partially introduced Ca2+ binding sites and its efficient refolding system from inclusion bodies

During the process of evolution, ancestral lysozymes evolved into calcium-binding lysozymes by acquiring three critical aspartate residues at positions 86, 91 and 92. To investigate the process of the acquisition of calcium-binding ability, two of the aspartates were partially introduced into human lysozyme at positions 86, 91 and 92. These mutants (HLQ86D, HLA92D and HLQ86D/D91Q/A92D), having two critical aspartates in calcium-binding sites, were expressed in Escherichia coli as non-active inclusion bodies. For the preparation of lysozyme samples, a refolding system using thioredoxin was established. This system allowed for effective refolding of wild-type and mutant lysozymes, and 100% of activity was recovered within 4 days. The calcium ion dependence of the melting temperature (Tm) of wild-type and mutant lysozymes was investigated by differential scanning calorimetry at pH 4.5. The Tm values of wild-type, HLQ86D and HLA92D mutants were not dependent on calcium ion concentration. However, the Tm of HLQ86D/D91Q/A92D was 4 degrees higher in the presence of 50 mM CaCl2 than in its absence, and the calcium-binding constant of this mutant was estimated to be 2.25(+/-0.25)x10(2) M(-1) at pH 4.5. Moreover, the calcium-binding ability of this mutant was confirmed by the result using Sephadex G-25 gel chromatography. These results indicate that it is indispensable to have at least two aspartates at positions 86 and 92 for acquisition of calcium-binding ability. The process of the acquisition of calcium-binding site during evolution of calcium-binding lysozyme is discussed.      

Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the tensile properties of PP/KT microcomposites was studied by uniaxial tensile test and the morphological structures of the stretched specimens were observed by scanning electron microscopy (SEM) and polarized optical microscopy (POM). We found that the Young’s modulus of PP/KT specimens increased with filler content, while the yield and break of the specimens are related to the filler particles size. The yield stress, the breaking stress and the ultimate elongation of PP/KT specimens were close to those of unfilled iPP specimens when the maximal filler particles size is less than a critical value, which is 7 μm at a crosshead speed of 10 mm/min and 3 μm at 200 mm/min, close to that of glass bead but far more than those of other rigid inorganic filler particles. The interfacial interaction was further estimated from yield stress, indicating that KT particles have a moderate interfacial interaction with iPP matrix. Thus, the incorporation of small KT particles can reinforce iPP matrix and simultaneously cause few detrimental effects on the other excellent tensile properties of iPP matrix, due to their organic nature, higher specific area, solid true-spherical shape and the homogenous dispersion of the ROF particles in microcomposites.     

Carrier transport properties in highly ordered smectic liquid crystal phase

We have designed and synthesized a new liquid crystalline phenylbenzothienobenzothiphene derivative, Ph‐BTBT‐4S‐3, in order to investigate the carrier transport properties in highly ordered smectic liquid crystal phase at a wide temperature range lower than room temperature enough to analyze them. Ph‐BTBT‐4S‐3 exhibits smectic E (SmE) phase, which is the one of highly ordered smectic liquid crystal phases, at the wide temperature range from 200°C to under ?130°C. Thanks to its wide temperature range of SmE phase, we could reveal the carrier transport properties in the low temperature range, which were well explained on the basis of Gaussian disorder model having a Gaussian width, σ, of 87 meV, which was larger than those of typical nonpolar liquid crystals of 40?60 meV and was attributed to additional dipole of a thioether group in the side chain.     

Investigation on force transmission of direct-drive thorax unit with four ultrasonic motors for a flapping microaerial vehicle

We fabricated a trial version of a thorax unit with four ultrasonic motors (USMs) to simulate a dragonfly-scale flapping micro aerial vehicle (MAV). Each wing was directly driven by a two-degree-of-freedom (2-DOF) transmission. An in-house tiny standing-wave USM capable of bidirectional rotation, which weighs just 0.13 g, was employed on trial. The transmission of the thorax unit converts the two USM rotations into strokes and flip motions of the wing. By implementing two 70-mm-long wings, we fabricated a prototype of a 4-DOF MAV and tested its performance. In a lift-compensated situation, upward, forward, and backward movements of the MAV were obtained. The flapping angular velocity was discussed based on quasi-static wing aerodynamics and was accountable for the motor power. Although the power of the USM should be improved, the quick wing drivability, adequate power transmission on the thorax unit, and potential of a 0.2 W motor power in a unidirectional-type USM promise the viability of a direct-drive multi-DOF dragonfly-scale MAV.