Influence of mixing cycle on the degree of mixing of calcite‐filled polyethylene upon stretching

The mixing cycle‐dependent degree of dispersion and degree of mixing of a calcite (calcium carbonate) agglomerate in high‐density polyethylene (HDPE), low‐density polyethylene (LDPE), and linear low‐density polyethylene (LLDPE) matrices upon stretching was investigated using three different techniques: mechanical property, morphological behavior, and image analyzer analyses. The mechanical properties analyzed in terms of the tensile strength and maximum elongation resulted in that the second mixing was the best for giving a better property for all systems except the LDPE system, which exhibited no significant difference between the second and third mixings. The morphological behavior of the three compounds were different, but no distinctive difference was observed to differentiate the degree of mixing from system to system. The number‐, weight‐, and z + 1‐average diameters of the air hole and the aspect ratio upon the stretching and mixing cycle were calculated to analyze the degree of mixing of the calcite‐filled composites. As a consequence, no difference in the average diameter of the air hole was obtained among the three systems, but the aspect ratios of the air hole varied significantly. Thus, the degree of dispersion and the degree of mixing may be influenced by the average calcite agglomerate size, the average diameter of the air hole, and the aspect ratio upon stretching and mixing cycles. Those factors would be formed by the difference in chemical characteristics upon various microstructures of polyethylene and its molecular weight and molecular weight distribution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 311–321, 2003     

Computational fluid dynamics (CFD) analysis and experimental study for toxic hazardous waste destruction in the cavity incinerator

We undertook numerical and experimental studies to develop a better incineration method for the destruction of CC1₄. A phenomenological model for the turbulent reaction of CC1₄, including a flame inhibition feature, has been successfully incorporated into a commercial code, simulating the incineration processes of this compound. The gaseous flow solution was obtained using SIMPLEST, a derivative of Patankar’s SIMPLE algorithm, with a k-ε turbulence model. A modified fast chemistry turbulent reaction model was developed to describe the flame inhibition due to the presence of CC1₄, considering the corresponding burning velocity data of these mixtures. An experiment was carried out on a 5.2 kW laboratory scale, transportable, cavity-type incinerator, which warrants a sufficient residence time and effective turbulent mixing by the formation of a strong recirculation region in a combustor. To this end, the specific configuration of the incinerator was manufactured to consist of two opposing jets and a rearward facing step. The calculated data were in close agreement with the experimental data for the concentrations of major species, such as CCI₄ and HCl, together with the temperature profiles. The experimental test gave the desired DRE of above 99.99%.     

Liquid Radial Dispersion in Liquid-solid Circulating Fluidized Beds with Viscous Liquid Medium

Liquid dispersion in the radial direction was investigated in the riser of a viscous liquid-solid fluidized bed 0.102 m in diameter and 3.5 m in height. Pressure fluctuations in the riser were also measured and analyzed to examine the behavior of fluidized particles. Effects of liquid velocity (0.15-0.45 m/s), solid circulation rate (2-8 kg/m²s), particle size (1-3 mm), and liquid viscosity (0.96-38 mPas) on pressure fluctuations and the liquid radial dispersion coefficient were determined. The infinite space model was employed to obtain the radial dispersion coefficient from the radial concentration profiles of the tracer. The pressure fluctuations were analyzed by means of autocorrelation coefficient as well as power spectral density function. The dominant frequency obtained from the autocorrelation coefficient or power spectral density function of pressure fluctuations decreases with increasing liquid viscosity or liquid velocity, but it increases with increasing particle size. The liquid radial dispersion coefficient decreases with increasing liquid velocity or viscosity, but it increases as the solid circulation rate or particle size increases. The liquid radial dispersion coefficient is related closely to the resultant behavior of fluidized particles. The radial dispersion coefficient has been well correlated with operating variables in terms of dimensionless groups.     

Accommodation and convergence in integral imaging 3D display

In this paper, we analyze the visual fatigue of integral imaging three‐dimensional (3D) display by studying the accommodation and convergence when viewing the integral imaging 3D images. The theoretical analyses show that there is no inconsistency between the accommodation and convergence distances, which means that the integral imaging 3D display has no visual fatigue. Experiments are implemented, and the results finally demonstrate the rationality of the theoretical analyses. These analyses can be quite beneficial for researchers to better understand the performances and promote the practical applications of the integral imaging 3D display.     

Measurement of minimum angle of resolution (MAR) in the stereoscopic display using the optotype of stereoscopic stimuli

In stereoscopic images, the crossing point of the viewing directions of the two eyes determines the perceived depth. Assuming that accommodation is affected by the positions of the crossing point, the effect of crossing point on minimum angle of resolution (MAR) was investigated. For 40 participants, MAR was measured by two‐alternative forced choice where Snellen optotype E of up and down directions were used as two kinds of stimuli. As the crossing point of the viewing direction of the left and right eyes moves farther from the sample display, the ability to identify the direction of letter E decreases at the optotype of the same line thickness. The change of MAR shows linear trends with respect to the optical power change that are the reciprocal of the distance from the participant to the crossing points located out of screen and on screen.     

Oil thermal annealed nano‐structured indium tin oxide thin films for display applications

Indium tin oxide‐coated thin films (200 nm) are deposited on glass substrates by using R.f. sputtering technique. Here, we investigate the influence of new technique of treatment, which is called as “oil thermal annealing” on the nano‐structured indium tin oxide thin films at fixed temperature (150 °C) which improves adhesion strength, electrical conductivity and optical properties (transmittance) of the films. Oil thermal annealing is used to reduce inherent defects that may be introduced during the prepared thin film and cooling processes. Proposed technique is highly suitable for liquid crystal displays, solar cells and organic light emitting diodes, and many other display‐related applications.     

Visual experience for autostereoscopic 3D projection display

In order to investigate visual experience for watching the autostereoscopic three‐dimensional (3D) projection display, we conduct a subjective evaluation experiment by a questionnaire when viewing video clips. Factor analysis is adopted to classify the evaluation items for the perpetual constructs of visual experience. Then a mixed design with repeated measurement analysis of variance with dimension and display duration as factors is carried out on the evaluation data to check the factorial effects and interactions for statistical significance. The results of factor analysis extract five factors including visual comfort, image quality, distortion, naturalness, and presence, which can be used as comprehensive indicators to evaluate the autostereoscopic 3D projection display. The results of analysis of variance indicate that image quality, which is used to assess two‐dimensional contents, is no longer applicable. It is necessary to give consideration to depth when evaluating 3D visual experience. Although 3D scenes enhance the overall subjective performance such as naturalness and presence, the health issues and stereoscopic distortion related to the introduction of depth cannot be ignored.     

Study of the miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) blends

The miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) (PEO/PVA) blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarizing optical microscopy. Because the glass‐transition temperature of PVA was near the melting point of PEO crystalline, an uncommon DSC procedure was used to determine the glass‐transition temperature of the PVA‐rich phase. From the DSC and DMA results, two glass‐transition temperatures, which corresponded to the PEO‐rich phase and the PVA‐rich phase, were observed. It was an important criterion to indicate that a blend was immiscible. It was also found that the preparation method of samples influenced the morphology and crystallization behaviors of PEO/PVA blends. The domain size of the disperse phase (PVA‐rich) for the solution‐cast blends was much larger than that for the coprecipitated blends. The crystallinity, spherulitic morphology, and isothermal crystallization behavior of PEO in the solution‐cast blends were similar to those of the neat PEO. On the contrary, these properties in the coprecipitated blends were different from those of the neat PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1562–1568, 2004     

Synthesis and physicochemical characterization of amphiphilic block copolymer self‐aggregates formed by poly(ethylene glycol)‐block‐poly(ϵ‐caprolactone)

Diblock copolymers with different poly(ε‐caprolactone) (PCL) block lengths were synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG‐OH, MW 2000) as initiator. The self‐aggregation behaviors and microscopic characteristics of the diblock copolymer self‐aggregates, prepared by the diafiltration method, were investigated by using ¹H NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG–PCL block copolymers formed the self‐aggregate in an aqueous environment by intra‐ and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations of the block copolymer self‐aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The partition equilibrium constants (K_v) of pyrene, measured by fluorescence spectroscopy, revealed that the inner core hydrophobicity of the nanoparticles increased with increasing PCL chain length. The aggregation number of PCL chain per one hydrophobic microdomain, investigated by the fluorescence quenching method using cetylpyridinium chloride as a quencher, revealed that 4–20 block copolymer chains were needed to form a hydrophobic microdomain, depending on PCL block length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3520–3527, 2006     

Relation of swelling and Tg depression to the apparent free volume of a particle‐filled,epoxy‐based adhesive

The effect of hygrothermal aging on a particle‐filled, epoxy‐based adhesive was studied using a gravimetric sorption technique. This study has explored moisture sorption characteristics as well as the associated behaviors of swelling and the depression of the glass transition temperature (T_g). We observed that the diffusion of water in this adhesive has a non‐Fickian behavior, and the depression of T_g proceeds to a definite value that is independent of the final equilibrium water content of the system. Our observations suggest that water diffuses into the polymer in a dual‐sorption mode, in which water resides in two populations. In one population, water is considered to occupy apparent free volume of the adhesive, and the second population water infiltrates polymer structure and forms hydrogen‐bonded clusters. Our results show that hygrothermal aging temperature and swelling do not alter the apparent free volume of this adhesive. We conclude that the constant value of T_g depression at saturation implies that only water in the apparent free volume is responsible for the T_g depression, whereas the swelling proceeds through the formation of hydrogen bonds in the adhesive. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1436–1444, 2003