Effect of shear memory on the coarsening behaviour of polystyrene and poly(vinyl methyl ether) blend

The effect of shear memory on the coarsening behaviour of polystyrene/poly(vinyl methyl ether) (PS/PVME) blend which shows a typical lower critical solution temperature (LCST)-type phase diagram has been thoroughly investigated for the near critical composition (PS/PVME=30/70) using a time-resolved light scattering technique. The measurements were carried out at 135 °C (20 °C above the quiescent cloud point) at two different directions, parallel and normal to the direction of flow. Different shear memories were generated in the melt using a simple shear apparatus of parallel plate geometry. The coarsening process was influenced to a great extent by the shear history of the blend over the time scale of the measurement. The average domain size of the dispersed particles obtained from the analysis of the light scattering data on the basis of Deby Bueche theory was found to be shear memory dependent. The coarsening process was elevated and suppressed at low and high shear memory, respectively. This behaviour was attributed to the shift of the cloud point observed under same values of shear rates. In addition, the coarsening behaviour of this blend was found to be flow direction independent due to the very high viscosity ratio of the blend, which led to in turn rather circular domains of PS in PVME matrix without any elongation or orientation in the direction of flow. Furthermore, the coarsening process for all the measured samples was followed the general power low, regardless the shear history and the flow direction of the blends. This result indicated that; the shear could only retard or elevate the rate of domain growth without any effect on the coarsening mechanism.     

Calcium catalysed steam gasification of Yallourn brown coal

Steam gasification of calcium-loaded Yallourn coal has been carried out with a thermobalance. Calcium catalyst showed a high activity at ≈950K. Calcium hydroxide, carbonate, acetate, nitrate and chloride exhibited similar catalyst effectiveness. The gasification rate increased with increasing the calcium loading, and at a loading of 5 wt%, complete gasification was attained within 25 min at 973 K. Comparison of the uncatalysed and catalysed rates showed that calcium catalyst can lower the reaction temperature by 150K. The impregnation of calcium salt on devolatilized char in place of raw coal resulted in the formation of rather large catalyst particles, and their activity was low. High temperature X-ray diffraction analysis revealed that the interconversion between calcium carbonate and oxide takes place readily in the gasification temperature region. Calcium carbonate was the predominant species during the gasification at 923 K. Catalysis of calcium was discussed in terms of a carbonate-oxide cycle mechanism.     

Studies on synthetic polymer plates with high surface energy. III. Diethylene glycol bis(allyl carbonate)–unsaturated sulfonic acid system

Synthetic polymer plates (GPs) with high surface energy were prepared by the two-step copolymerization process previously reported, using diethylene glycol bis(allyl carbonate) (CR-39) as M₁ monomer and unsaturated sulfonates [sodium vinyl sulfonate (VS^?Na⁺), potassium styrene sulfonate (StS^?K⁺), and sodium 2-sulfoethyl methacrylate (SEM^?Na⁺)] as M₂ monomer. The contact angle (θ_H) of water for the acid-treated (immersed in an aqueous 0.1 N HCl solution for 2 h) GPs decreased in the order StS^?K⁺, VS^?Na⁺, and SEM^?Na⁺. In the case of M₂ = SEM^?Na⁺, the θ_H value was about 20°. By adding NaCl in the immersion solution and changing the pH of the immersion solution, the θ_H values for the CR-39–SEM^?Na⁺ GPs were lowered to 18.9 and 13.1°, respectively. The θ_H values for the above GPs were smaller than those for the CR-39–acrylic acid or the CR-39–methacrylic acid GPs in the previous report, whereas the contact angle (θ_Na) of water for the former after alkali treatment (immersed in an aqueous 0.1 N NaOH solution for 2h) was larger than those for the latter. The former had durability of water wettability superior to the latter because of the difference in dissociation characteristic of the respective functional group.     

Effects of AN-contents and shear flow on the miscibility of PC/SAN blends

The miscibility of polycarbonate (PC) with styrene-co-acrylonitrile random copolymer (SAN) has been systematically investigated as functions of acrylonitrile content and shear flow. Various AN-contents ranged from 11 to 74 wt% and different simple shear flow values up to 90 s⁻¹ have been used to explore the effect of both material and proceeding parameters on the miscibility of PC and SAN blends. The finest phase dispersion of the SAN particles was observed at AN=25 wt% for PC/SAN=70/30 blends under the same processing condition using scanning electron microscope (SEM). The obtained morphologies indicated that PC and SAN could form a partial miscibility blend and the maximum miscibility occurred at AN=25 wt%. This observation was supported by considering the shifts in the glass processes of the two rich phases of the blend using the dynamical mechanical analysis (DMA) measurements. The optimum interaction of the two components at AN=25 wt% calculated from ellipsometric technique was found to be the only responsible parameter for the high miscibility of the blend. The viscoelastic properties of the pure polymer components were found to play a minor role in the obtained morphologies. The effect of simple shear flow on the morphology of PC/SAN-25=70/30 blend has been also investigated using a special shear apparatus of parallel plate geometry. It has been found that the dispersed phase of SAN was elongated and broken-up in the direction of flow with weaker contrast at high shear rates. The shear rate was found to enhance the miscibility of SAN (dispersed phase) in the PC matrix to a great extent as seen in the weak contrast of the two phases observed by transmission electron microscope (TEM).     

Dietary medium- and long-chain triacylglycerols accelerate diet-induced thermogenesis in humans

This study investigated the effects of a liquid meal containing medium- and long-chain triacylglycerols (MLCT) on diet-induced thermogenesis (DIT) and was conducted in double-blind cross-over manner. Twenty subjects participated in this examination. The subjects consumed the liquid meal, which was made with 14 g of canola oil (LCT, long-chain triacylglycerols) or MLCT containing about 12% medium-chain fatty acids (MCFA). Oxygen consumption and carbon dioxide production were measured by indirect calorimetry. Resting energy expenditure (REE) was determined based on there parameters, applying the equation of Weir. Increase in DIT after ingesting the liquid meal with MLCT during 6h was significantly greater than with LCT (P<0.05). The results suggest that the substitution of MLCT for cooking oil is useful to control body weigh and fat in subjects.     

Effect of dietary lard containing higher alpha-linolenic acid on plasma triacylglycerol in rats

It is well known that the consumption of n-3 polyunsaturated fatty acid (PUFA) decreases the plasma triacylglycerol (TAG) level. The technology of elevating the content of n-3 PUFAs in pig meat has already reached a practical level. In this study, the effects of dietary lard containing higher alpha-linolenic acid (LNA) on plasma TAG were compared with those of normal lard in rats. The rats were fed a diet containing either 10% normal lard or a high linolenic lard for 4 weeks. The plasma and liver TAG levels in the high linolenic lard group were significantly lower than those in the normal lard group. The activity of the fatty acid synthase (FAS) of the liver in the high linolenic lard group was significantly lower than that in the normal lard group. The contents of n-3 PUFAs in hepatic total lipid, TAG fraction, and the phospholipids (PLs) fraction increased in the high linolenic lard group. The results indicate that the high linolenic lard suppressed hepatic FAS activity compared with the control lard, resulting in a lower concentration of plasma TAG. These results also suggest that pig meat containing high LNA may be more nourishing than normal pig meat.     

Safety of dietary conjugated linoleic acid (CLA) in a 12-weeks trial in healthy overweight Japanese male volunteers

A study was conducted to investigate the short-term safety of dietary conjugated linoleic acid (CLA) in overweight Japanese male volunteers. The study design was a randomized, double-blind placebo-controlled trial including 60 healthy overweight volunteers (body mass index (BMI), 25 approximately 35 kg/m(2)). The subjects were randomly assigned to three groups: 5.4 g CLA-triacylglycerol (3.4 g as CLA), 10.8 g CLA-triacylglycerol (6.8 g as CLA) and placebo (10.8 g safflower oil) daily for 12 weeks. The CLA-triaclyglycerol contained 9c,11t- and 10t,12c-isomers at an equal proportion. The safety was evaluated by analyses of blood parameters and by clinical examinations at the baseline, and at 6 and 12 weeks, including vital signs and adverse effects. All subjects completed the study. The occurrence of adverse events tended to be higher in the CLA groups than in the placebo group, but all of the adverse events were mild to moderate, within normal ranges, and temporary. Serum aspartate aminotransferase (AST) activity did not differ significantly between the groups at 12 weeks, but in the high CLA group it was slightly increased from the baseline. Serum alanine aminotransferase (ALT) activity was higher in the high CLA group than in the placebo group after 12 weeks and was higher than at the baseline in both CLA groups. However, statistical analysis of the population of apparently healthy volunteers who had normal blood parameters at the baseline revealed that AST and ALT levels did not differ significantly among the 3 groups at 12 weeks. Moreover, no clinically significant changes in vital signs were observed in any of the groups. These results indicate that CLA at a dose of 3.4 g/day is a safe dietary level in healthy Japanese populations in terms of the parameters examined.     

Electronic and magnetic properties of acid-adsorbed nanoporous activated carbon fibers

Nanoporous activated carbon fibers (ACFs) feature 3D disordered networks of nanographite domains that consist of stacks of 3-4 nanographene sheets each. At the peripheries of the nanographene sheets, the localized spins of a nonbonding edge state are created. The magnetic properties of the edge-state spins in ACFs are investigated in relation to the interaction with acid molecules adsorbed in the nanopores. HCl molecules condensed physisorptively in the nanopores mechanically compress the nanographite domains, resulting in the reduction of the magnetic moments of the edge-state spin in the form of a magnetic switching effect. HNO₃ molecules, which have significant oxidation ability, are subjected to charge transfer from the nanographite domains. This induces a two-step reduction in the edge-state spin concentration, wherein the first and second steps are related to the charge transfer with the nanographene sheets that directly face the nanopores and that with the nanographene sheets in the interior of the nanographite domains, respectively. In diluted HNO₃, the blockade by water molecules prevents the interaction of the HNO₃ molecules with the interior nanographene sheets, allowing for charge transfer only with the graphene sheets that directly face the nanopores; this results in a single-step change in the spin concentration.     

Radiation‐induced crosslinking and mechanical properties of blends of poly(lactic acid) and poly(butylene terephthalate‐co‐adipate)

Blends of poly(L ‐lactic acid) (PLLA) and poly (butylene terephthalate‐co‐adipate) (PBTA) were prepared at ratios of 50 : 50, 60 : 40, and 80 : 20 by melt blending in a Laboplastomill. Improved mechanical properties were observed in PLLA when it was blended with PBTA, a biodegradable flexible polymer. Irradiation of these blends with an electron beam (EB) in the presence of triallyl isocyanurate (TAIC), a polyfunctional monomer, did not cause any significant improvement in the mechanical properties, although the gel fraction increased with the TAIC level and dose level. Irradiation of the blends without TAIC led to a reduction in the elongation at break (E_b) but did not show a significant effect on the tensile strength. E_b of PBTA was unaffected by EB radiation in the absence of TAIC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Numerical analysis of a path-length-resolved spectrum of time-varying scattered light field

The path-length-resolved power spectrum of a time-varying scattered light field measured by a time-of-flight method or low-coherence interferometry is evaluated by a new numerical simulation algorithm. The path-length-resolved power spectrum is theoretically derived by combining diffusing-wave-spectroscopy theory and radiative-transfer theory. The proposed algorithm, using the Monte Carlo method, is used to determine the scattering configurations and numerically calculate the power spectrum. The path-length distribution, path-length-dependent scattering order distribution, and path-length-resolved power spectrum are demonstrated numerically over all scattering orders. The resultant power spectra agree with experimental results measured by the low-coherence-dynamic-light-scattering method.