Fatigue behaviour of out-of-plane gusset joints with one-side fillet weld

In previous studies, many fatigue tests have been performed to investigate the fatigue behaviour of out-of-plane gusset welded joints. However, fatigue behaviour of out-of-plane gusset joints with a one-side fillet weld has not yet been clarified sufficiently. In this research, in order to quantitatively clarify the behaviour, welding residual stress at the weld toes of the joint was measured by a cutting method. In addition to this, fatigue tests were carried out on the joints with a one-side weld and turn-around weld. The plate thickness is 9 mm and the weld size is 10 mm. Moreover, finite element stress analyses were conducted on the test specimen models and parametric models with different main plate and gusset plate thickness. Their results show that fatigue cracks for out-of-plane gusset joints with a one-side fillet weld initiate from both weld toes at the start and end points of weld beads and non-penetration weld of the gusset side. Also, the crack initiation points are different depending on the weld arrangement; however, their fatigue strengths are almost same.     

Latex produced with carboxylic acid comonomer for waterborne coatings: Particle morphology variations with changing pH

Carboxylic acid comonomers are often added to latex formulations to improve colloidal stability and to help control the physical structure of composite (core-shell type) particles. We have performed a systematic study of the incorporation of methacrylic acid (MAA) within styrene/butyl acrylate copolymer seed latices, and determined the eventual effect on the morphology of the composite particles when using a second-stage monomer that is either polar (MMA) or nonpolar (BMA). These latices have been produced in batch and semibatch reactions in the pH range of 3–7. At low pH, the MAA groups are not ionized, but at the higher pH they may be nearly completely ionized. Here, we report that for batch reactions carried out within the above pH range, the latex particle morphologies of the PMMA second-stage systems change dramatically with increasing pH, while those for the PBMA system do not change at all. These results show that one cannot easily generalize the effect of acid comonomers on the morphology of composite latex particles, as this depends upon the choice of the copolymers in the latex and the process characteristics of the polymerization reaction. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

CO2 absorption properties of Brønsted acid-base ionic liquid composed of N,N-dimethylformamide and bis(trifluoromethanesulfonyl)amide

The solubilities of CO₂ and the liquid densities in a Brønsted acid-base ionic liquid, [DMFH][Tf₂N], composed of N,N-dimethylformamide (DMF) and bis(trifluoromethanesulfonyl)amide (HTf₂N) have been investigated at high pressures and at different temperatures. The results were compared with those in DMF and a typical 1-butyl-3-methylimidazolium analogue with the same anion, [BMIM][Tf₂N]. The mole fraction scaled solubilities of CO₂ in the three liquids showed a slight increase in the following order, DMF < [DMFH][Tf₂N] < [BMIM][Tf₂N], whereas more remarkable difference was observed in the volume scaled concentrations of CO₂, [BMIM][Tf₂N] < [DMFH][Tf₂N] « DMF, mainly due to the bulkiness of liquid entities.     

Volumetric properties of carbon dioxide + 2-butanol mixtures at 313.15 K

Volumetric properties were measured of carbon dioxide + 2-butanol mixtures at 313.15 K, using the vibrating tube Anton Paar DMA 512P density meter. In the present experiments, no analytical instrument was required. The saturated pressures were also measured of carbon dioxide + 2-butanol mixtures at 313.15 K by the synthetic method. The experimental data obtained were correlated with the density equation, Soave-Redlich-Kwong (SRK) equation of state, and the pseudocubic equation of state.     

Development of a Highly Sensitive β-Glucan Detection System Using Scanning Single-Molecule Counting Method

To overcome the limitations of the Limulus amebocyte lysate (LAL) assay method for the diagnosis of invasive fungal infection, we applied a reaction system combining recombinant β-glucan binding proteins and a scanning single-molecule counting (SSMC) method. A novel (1→3)-β-D-glucan recognition protein (S-BGRP) and a (1→6)-β-glucanase mutant protein were prepared and tested for the binding of (1→6)-branched (1→3)-β-D-glucan from fungi. S-BGRP and (1→6)-β-glucanase mutant proteins reacted with β-glucan from Candida and Aspergillus spp. Although LAL cross-reacted with plant-derived β-glucans, the new detection system using the SSMC method showed low sensitivity to plant (1→3)-β-D-glucan, which significantly improved the appearance of false positives, a recognized problem with the LAL method. Measurement of β-glucan levels by the SSMC method using recombinant β-glucan-binding proteins may be useful for the diagnosis of fungal infections. This study shows that this detection system could be a new alternative diagnostic method to the LAL method.     

Novel hydrolyzable and biodegradable cationic gemini surfactants: Bis(ester-ammonium) dichloride having a butenylene or a butynylene spacer

Novel cationic gemini surfactants, bis(ester-ammonium) dichlorides having a butenylene or a butynylene spacer and an oxycarbonyl group in the lipophilic part, were prepared conveniently and almost quantitatively by the reaction of the corresponding mono(ester-amine) with a highly reactive allylic- or propargylic dichloride. Most of these surfactants showed excellent surface-active properties and good biodegradability. The effects of the structure of spacer, the position of the oxycarbonyl group in the lipophilic part, the alkylene length between the oxycarbonyl and the ammonio groups, and the acyl chain length of the surfactants on their surface-active properties were examined.     

Activities of lysozyme complexed with polysaccharides and potassium poly(vinyl alcohol sulfate) with various degrees of esterification

Enzymatic activities of complexes of lysozyme (Lyz) with polysaccharides and potassium poly(vinyl alcohol sulfate) (KPVS) with different degrees of esterification (D _e) were studied as a function of pH, substrate concentration, and temperature. Molar masses and radii of polyelectrolytes and complexes and fluorescence spectra of Lyz molecules after complexation were examined by means of dynamic and static light scattering and fluorescence spectroscopy measurements. The relative activities of KPVS–Lyz complexes toward Micrococcus lysodeikticus and the number of hydroxyl groups in the formed complex increased with the decrease in D _e in KPVS molecules, whereas molar masses and radii of the complexes decreased. Moreover, kinetic parameters and fluorescence spectral data analysis indicate that activities and microenvironments around the active sites in Lyz complexed with KPVS with low D _e (0.130) and chondroitin sulfate C were nearly equal to that of native Lyz. These results indicate that the decrease in activities through complexation is mainly caused by the steric hindrance between Lyz and substrate due to aggregation of complexes, not by conformational change in Lyz molecules. Therefore, polyelectrolytes with hydroxyl groups have great potential as enzyme immobilization matrixes.     

Origin of enhanced cold crystallization rate for freeze‐dried poly(L‐lactide) from solutions

Poly(L ‐lactide) (PLLA) freeze‐dried from dilute 1,4‐dioxane solutions exhibited very porous structure composed of thin membranes of which the mean thickness was estimated to be 104–135 nm. Heating measurements of differential scanning calorimetry (DSC) showed that the freeze‐dried PLLA (FDPLLA) exhibits an exothermic peak of cold crystallization at 78–81°C, which is at least 20 K lower than that for a quenched amorphous bulk PLLA. In accord with this, the overall rate of isothermal cold crystallization was revealed to be greater for the FDPLLA than that for the bulk. The origin of such high crystallizability of FDPLLA is attributed to its large surface area where the chain mobility is greater than in the bulk PLLA. The exothermic peak in the DSC trace shifted to a further lower temperature when the FDPLLA is immersed in ligroin (nonsolvent), which also suggests a major role of the free surface in enhancing the cold crystallization rate. On the other hand, the density and the chain conformational feature of the FDPLLA were revealed to be identical to the bulk PLLA. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Preparation of liquid crystalline networks doped with azobenzene molecules and their photochemical grating formation behavior

Liquid crystalline (LC) networks with macroscopically uniaxial molecular orientation were prepared by photopolymerization of mixtures of LC mono‐ and diacrylates and a donor–acceptor azobenzene compound in a homogeneous glass cell at the nematic phase, and their photoresponsive properties were investigated. The transparency of the LC networks decreased with a decrease in the crosslinking density with LC diacrylate. The LC networks crosslinked with a few mol percent of LC diacrylate showed an enantiotropic phase transition from an anisotropic phase to an isotropic phase as well as high transparency. Formation and removal of the grating were investigated by irradiating two writing beams with an argon ion laser. Grating less than 1.0 μm could be achieved, and the response time of formation and removal of the grating were in a range of a few tens of microseconds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 943–951, 2003     

Bonding properties of epoxy resins containing two mesogenic groups

Liquid‐crystalline epoxy resins, with introduced aliphatic chains between two mesogenic groups, were synthesized and their adhesive bonding properties were compared to those of the bisphenol‐A–type epoxy resin and the liquid‐crystalline epoxy resin, previously reported. The bonding strength of the former resin system was higher than that of the two later systems. We suggest that the high bonding strength of the twin mesogenic epoxy resins, cured with an aromatic amine, was attributable to the large plastic deformation of the adhesive layer in the fracturing process. We also investigated the effects of the aliphatic chain length in the twin mesogenic epoxy resin on their dynamic mechanical and bonding properties. The bonding strength of the cured twin mesogenic epoxy resins increased with an increase in the aliphatic chain length. We suggest that the high bonding strength of the system introduced by the long aliphatic chain was attributable to the large plastic deformation of the adhesive layer because of the higher network mobility. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3721–3729, 2004