Process Intensification of Living Cationic Polymerization of Isobutylene by a Flow Reaction System

Increasing the reaction temperature of the living cationic polymerization of isobutylene is crucial for industrial production due to the cost of refrigeration. The reaction temperature increase was achieved with an accelerated reaction rate using a flow reaction system. The polymerization conditions, including the flow reactor design, were based on the results of kinetic studies. Utilizing a milli‐scale flow reactor, polyisobutylene, which has a narrow molecular weight distribution, was obtained within a considerably short residence time at a high temperature. Furthermore, it was confirmed that the value of M_w/M_n correlates with the product of the Reynolds number and the angle of collision.     

Ketones from carboxylic acids over supported magnesium oxide and related catalysts

Silica-supported alkaline earth oxides revealed excellent activity to convert acetic acid selectively into acetone in a vapor-phase fixed-bed flow system. Acetone was obtained through the cyclic formation of alkaline earth acetate followed by decomposition. Magnesium oxide should be supported on the silica surface without formation of magnesium silicate, which was inactive for the present reaction. Attempted syntheses of benzophenone and acetophenone are also described.     

Copolymerization of phenylacetylene with various acetylenes by W- and Mo-based catalysts

In the copolymerization of phenylacetylene with various acetylenes catalysed by WCl₆·Ph₄Sn, the relative reactivity of monomer decreased with increasing steric effect of monomer, e.g. HC  Cn-Bu, HC  Cn-Hex > HC  CPh, HC  Cs-Bu > HC  Ct-Bu, MeCCPh, CICCPh. While 1-chloro-2-phenylacetylene (a disubstituted acetylene) showed high reactivity in the homopolymerization by Mobased catalysts, the reactivity was remarkably depressed in the presence of phenylacetylene as comonomer. Based on these results, the relative reactivity of the acetylenic monomers in copolymerization was explained in terms of competitive coordination of monomers to the propagating end.     

Synthesis,Characterization, and Application of Mesoporous Silica Functionalized with Alkyl‐Hydroperoxides

A variety of alkyl hydroperoxides such as tert‐butyl‐, tert‐octyl‐, 1‐cyclopentyl‐, 1‐cyclohexyl‐, 3,4‐disubstituted‐1‐cyclohexyl‐, n‐propyl, and n‐undecyl‐hydroperoxides have been functionalized onto ordered mesoporous silica, SBA‐15, from the corresponding covalently anchored synthons. All the tert‐hydroperoxides are prepared by autoxidation using molecular O₂ and an initiator, whereas other hydroperoxides are obtained by reaction with H₂O₂. For autoxidation, the use of a combination of an azoinitiator (AIBN) and N‐hydroxyphthalimide increased the hydroperoxide yield compared with using the azoinitiator alone. Synthons containing two or more tert‐ and sec‐hydrogens lead to higher peroxide yield compared to synthons with a single reactive site. Oxidation of Si–OH (silanol groups) with acidic H₂O₂ at low temperature produces Si–OOH. Reusability of these alkyl hydroperoxides is carried out by oxidation of alcohols obtained from the corresponding alkyl hydroperoxides using H₂O₂. Both the covalently anchored synthons and the resulting hydroperoxides are thoroughly characterized by powder X‐ray diffraction, ¹³C cross‐polarized magic angle spinning NMR, TG/DTA, Fourier transform IR spectroscopy, sorption, and surface area measurements. The quantification of the amount of alkyl hydroperoxide was carried out by iodometric titration using a thio solution. The hydroperoxides exhibit high activity for the epoxidation of styrene to styrene oxide and exhibit reasonably high efficiency for oxygen transfer.     

Effect of plasma surface modification on electrical conduction in polyethylene

High-density polyethylene films 50 μm thick were exposed to the downstream plasma flow of RF glow discharges in argon, hydrogen, or oxygen. It was found that many transvinylene and unreacted radicals remain after the argon or hydrogen plasma treatment, and that carbonyl groups are formed in the oxygen plasma treatment. The conduction current was smaller in the hydrogen-plasma treated samples and the samples exposed to oxygen or ozone after hydrogen-plasma treatment than in the untreated samples. Thermal pulse current measurements indicate that the treated surface layer traps electrons or holes and reduces the field strength at the electrode surface, thus suppressing further injection of electrons or holes.     

Calcium silicate structure and carbonation shrinkage of a tobermorite-based material

Carbonated autoclaved aerated concretes (AACs) show no shrinkage at a degree of carbonation approximately less than 20%. The ²⁹Si MAS NMR spectrum showed that at a degree of carbonation less than 25%, the typical double-chain silicate anion structure of tobermorite-11Å was well maintained and interlayer Ca ions were exchanged with protons. This corresponded to the absence of carbonation shrinkage at a degree of carbonation less than 20%. When the degree of carbonation increased from 25% to 50% up to 60%, the double-chain silicate anion structure of tobermorite-11Å was decomposed and Ca ions in the Ca-O layers were dissolved, showing a possible mechanism of carbonation shrinkage.     

Cloning and characterization of a 4-nitrophenol hydroxylase gene cluster from Rhodococcus sp. PN1

A 4-nitrophenol (4-NP)-degrading bacterium was isolated from activated sludge and identified as a Rhodococcus sp. This bacterium, designated as strain PN1, could utilize 4-NP as a sole carbon, nitrogen and energy source. Degradation tests of 4-NP using cell suspensions of strain PN1 revealed that the degradation was induced by 4-NP and that 4-nitrocatechol (4-NC) was one of the metabolites. A gene library was constructed from the total DNA of strain PN1 and introduced into Rhodococcus rhodochrous ATCC 12674. Two recombinant strains showed 4-NP hydroxylase activity, and a 9.1-kb DNA fragment encoding the activity was isolated from one of the strains. In addition, a 2.4-kb smaller fragment expressing the activity was subcloned from the 9.1-kb fragment and sequenced. The sequence analysis showed that the fragment encodes a two-component 4-NP hydroxylase, the predicted amino acid sequence of which exhibits significant similarity to those of phenol hydroxylases and 4-hydroxyphenylacetate 3-hydroxylases belonging to the two-component flavin diffusible monooxygenase (TC-FDM) family proposed by Galán et al. (J. Bacteriol., 182, 627-636, 2000).     

Rate Effects on the Stress-Strain Behaviour of Eps Geofoam

The rate-dependency of the stress-strain behavior of EPS (Expanded Polystyrene) geofoam with densities of 19.3 and 28.0 kg/m³ was investigated by performing unconventional unconfined compression tests. A set of monotonic loading (ML) tests were performed at different constant values of vertical (axial) strain rate, ε_v. The ε_v value was stepwise changed many times and several sustained loading (SL) tests were performed during otherwise ML at a constant ε_v in other tests. A number of SL tests were performed during global unload and reload cycles to infer the stress-strain relation when ε_v=0. The elastic properties were evaluated by applying minute unload/reload cycles during otherwise ML. The rate-dependent stress-strain behaviour observed in these tests was described by an elasto-viscoplastic model (i.e., a non-linear three-component model), for which the vertical (axial) stress, σ_v, consists of inviscid and viscous components, σ_v^f and σ_v^v, while ε_v consists of elastic and irreversible components, ε_v^e and ε_v^ir. It is shown that the viscous property of EPS geofoam is of Isotach type in that, under the loading conditions where ε_v^ir is always positive, the current σ_v^v value is a unique function of instantaneous ε_v^ir and ε_v^ir, therefore the strength increases with ε_v. This viscous property was quantified based on the test results and incorporated into the model. The rate-dependent stress-strain behaviour, including the creep behaviour, observed in the experiment is simulated very well by the proposed model. In particular, the fact that the creep strain becomes significant when the sustained σ_v value becomes larger than the inviscid yield vertical stress is well simulated.