Flow properties of molten ethylene–vinyl acetate copolymer and melt fracture

In an investigation of the behavior and formation mechanism of melt fracture the flow properties of molten ethylene–vinyl acetate (EVA) copolymer in the region of high shear rate were measured with a capillary-type rheometer. EVA copolymer differs slightly in flow curve from low-density polyethylene (LDPE); it seems, however, that the difference is due to the difference in molecular weight distribution (MWD) rather than to the materials themselves. The fluidity of molten EVA copolymer having a narrow MWD is equivalent to that of LDPE having a broad MWD and, generally, EVA copolymer has a higher fluidity than LDPE. It is expected that the fluidity increases with incorporation of vinyl acetate at the same MWD and the same M?_w. The critical shear rate increases with melt index and temperature. It cannot be found that the materials themselves and the MWD directly influence the critical point of melt fracture formation when the melt index is taken as a parameter. The critical viscosity (η_c) at which melt fracture forms decreases in an almost straight line with an increase of melt index. It was found from the studies of end correction and behavior of melt fracture formation that melt fracture occurs at the inlet of the die, and it is supposed that the melt fracture formation is caused by the elastic turbulence in the flow pattern due to a failure of recoverable shear strain at the die inlet.     

Determination of diffusion coefficient of oxygen in γ-iron from measurements of internal oxidation in Fe-Al alloys

The internal oxidation of iron alloys containing between 0.069 and 0.274 wt pct aluminum was investigated in the temperature range from 1223 to 1373 K for the purpose of determining the diffusion coefficients in γ-iron as well as in the internal oxidation layer. A parabolic rate law is obeyed in the internal oxidation of the present alloys. The rate constant for penetration of the oxidation front, the oxide formed, and the concentration of aluminum in the oxidation layer were determined. Pronounced enrichment of aluminum in the oxidation layer was observed, resulting from the counterdiffusion of aluminum. The oxygen concentration at the specimen surface was determined by combining the thermodynamic data on the dissociation of FeO and the solution of oxygen in y-iron. The diffusion coefficient of oxygen in the internal oxidation layer,D _o ¹⁰ , was evaluated on the basis of the rate equation for internal oxidation.D _o ¹⁰ increases at a given temperature as the volume fraction of oxide,f ¹⁰, in the oxidation layer increases. The diffusion coefficient of oxygen in γ-iron,D _o, was determined by extrapolation ofD _o ¹⁰ = 0.D _o may be expressed as $$D_o = \left( {1.30\begin{array}{*{20}c} { + 0.80} \\ { - 0.50} \\ \end{array} } \right) \times 10^{ - 4} \exp \left[ { - \frac{{166 \pm 5(kJ \cdot mol^{ - 1} )}}{{RT}}} \right]m^2 \cdot s^{ - 1} .$$ D _o is close to the diffusion coefficients of carbon and nitrogen in γ-iron.     

STM-induced light emission from thin films of perylene derivatives on the HOPG and Au substrates

We have investigated the emission properties of N,N'-diheptyl-3,4,9,10-perylenetetracarboxylic diimide thin films by the tunneling-electron-induced light emission technique. A fluorescence peak with vibronic progressions with large Stokes shifts was observed on both highly ordered pyrolytic graphite (HOPG) and Au substrates, indicating that the emission was derived from the isolated-molecule-like film condition with sufficient π-π interaction of the perylene rings of perylenetetracarboxylic diimide molecules. The upconversion emission mechanism of the tunneling-electron-induced emission was discussed in terms of inelastic tunneling including multiexcitation processes. The wavelength-selective enhanced emission due to a localized tip-induced surface plasmon on the Au substrate was also obtained.     

Female Sex Pheromone Polymorphism in Adzuki Bean Borer, Ostrinia scapulalis, Is Similar to That in European Corn Borer, O. nubilalis

Individual analysis of the female sex pheromone of the adzuki bean borer, Ostrinia scapulalis, has shown that the sex pheromone of this species comprised (E)-11-tetradecenyl acetate (E11–14:OAc) and (Z)-11-tetradecenyl acetate (Z11–14:OAc) at variable blend ratios. The pheromone blend could be tentatively categorized into three types with respect to the proportion of E11–14:OAc: E type (94–100%, median 99.2%), Z type (0–16%, median 3.0%), and intermediate type (I type, 48–85%, median 63.7%). In addition to the identity of components, the blend ratios in the three types were similar to those of the E strain, Z strain, and hybrid of the European corn borer, O. nubilalis, respectively. This finding suggests that two closely related but morphologically distinct species, O. scapulalis and O. nubilalis, share almost the same sex pheromone communication systems. The significance of this similarity in the two sibling species is discussed.     

Host egg kairomones essential for egg-larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae)

Several components of an internal kairomone were identified inside eggs of the host,Adoxophyes sp. (Lepidoptere: Tortricidae), that releases egg deposition of the egg-larval parasitoid,Ascogaster reticulatus Watanabe (Hymenoptera: Braconidae). Pupal hemolymph with the same activity as an internal host egg kairomone was used as a convenient test sample. Heat-treated pupal hemolymph was chromatographed on a Sephadex G-25 column. Each fraction was bioassayed and reacted with ninhydrin. The active fractions were ninhydrin-positive. Each fraction was placed onto an araino acid analyzer, which showed that the amino acids were most abundant in active fractions. Among 22 amino acids, alanine, arginine, glycine, histidine, isoleucine, leucine, methionine, proline, serine, tryptophan, and valine were active. The mixture of these active amino acids was as active as the egg-mass homogenate at the same ratio and concentration, suggesting that the most important component as the kairomone in a host egg is the mixture of several amino acids.     

Preparation of phthalocyanine ultrathin film via layer-by-layer assembly

Phthalocyanine ultrathin films were prepared by a successive dip/dry process of hydroxy-group-bearing substrates into a dilute solution of phthalocyanine with silanol group at its coordination center (Pc). Amounts of adsorbed Pc on the substrate were monitored using a quartz crystal microbalance. At each dip/dry cycle, the adsorbed Pc corresponded to the mass of a single Pc layer flat on the surface. On the other hand, similar results could not be achieved with a pre-polymerized Pc, which showed Langmuir-type adsorption onto the substrate, probably due to the forming of a horizontally aligned monolayer. The Pc ultrathin film was specifically formed on an n-hexanol-presented substrate, although the Pc ultrathin films could not be formed with shorter ethanol- or longer undecanol-presented substrates. Furthermore, a hetero-structured Pc ultrathin film was prepared using an alternative second component Pc.     

Computer-aided design of surface modified adsorbent for adsorption of 5-hydroxy-methyl-furfural

The saccharide containing in high-starch crops could be converted into various products such as 5-hydroxy-methyl-furfural (HMF) which could be used to manufacture plastics. Currently, most of plastics are produced from petroleum feedstock that is one of the main sources of greenhouse gases. Therefore, the use of HMF produced from high-starch crops might reduce the generation of greenhouse gases since the high-starch crops is renewable. For example, d-fructose derived from high-starch crops could be decomposed into HMF in concentrated hydrochloric acid solution. The HMF could be effectively recovered by phenyl groups surface modified silica gel (PMSG) adsorbent during the decomposition process. However, the optimum loading of phenyl groups on the silica gel surface of PMSG would rely on time-consuming experimental works. Therefore, this research focuses on using Molecular Mechanics Simulator based on frontier orbital theory to obtain the optimum loading of phenyl groups on the silica gel in order to reach the maximum adsorption capacity of HMF. The simulated optimum loading of phenyl groups on the silica surface was about 0.5 mequiv./g. This dosage was in consistent with the value obtained from the experimental tests.     

Preparation of amphiphilic carbon black by postgrafting of polyethyleneimine to grafted polymer chains on the surface

Summary To prepare amphiphilic carbon black, we investigated the postgrafting reaction of polyethyleneimine (PEI) with pendant glycidyl groups of grafted polymer on carbon black surface. The grafting of polymers having pendant glycidyl groups onto carbon black surface was achieved by the copolymerization of glycidyl methacrylate (GMA) with methyl methacrylate (MMA) initiated by azo groups introduced onto the surface. Pendant glycidyl groups of poly(GMA-co-MMA)-grafted carbon black was found to react with PEI, and the corresponding polymers postgrafted to the grafted copolymer chains on carbon black surface: the percentage of PEI-postgrafting was readily controlled by the reaction conditions. PEI-postgrafted to poly(GMA-co-MMA)-grafted carbon black, whose PEI postgrafting is 3.9% showed amphiphilic nature and acted as an emulsifier. Received: 13 April 1998/Revised version: 20 May 1998/Accepted: 22 May 1998     

Geographic Variation in Sex Pheromone of Asian Corn Borer, Ostrinia furnacalis, in Japan

Geographic variation in the sex pheromone of the Asian corn borer, Ostrinia furnacalis (Guenée), was surveyed in populations sampled at four locations ranging from 39.7°N to 32.9°N in Japan. The sex pheromone of the three northern populations was composed of (E)- and (Z)-12-tetradecenyl acetates with a mean E proportion of 36–39%. The southernmost population (Nishigoshi) had the same components but with a significantly higher E composition of 44%. The frequency distribution of the E ratio in the Nishigoshi population exhibited a small peak near 38% and a major peak near 46%. A family-wise analysis of the sex pheromone of this population confirmed that there were two distinct phenotypes regarding the E ratio. An 46% E strain inhabits southern parts of Japan, in addition to an 38% E strain, which seems to be predominant in other regions of Japan.