HEAT AND MASS TRANSFER WITH POLYCONDENSATION IN RESIN FILM DURING DRYING

ABSTRACT

In a drying process of dielectric resin films coated on electric conductive substances, phenomena such as polymerization of monomers, by-products yield, shrinkage and stress generation lake place simultaneously in addition to heat and mass transfer. For the enhancement of the drying with high efficiency and high quality, it is important to understand the drying mechanism. In this paper, the characteristics of heat and mass transfer in the resin film including polycondensation reaction are presented. The apparent drying rate of polyamideimide varnish films was measured in two different heating modes of radiation and convection. The reaction rate of polycondensation was analyzed both by the thermogravimetry and the differential scanning calorimetry. The apparent drying rate began to drop remarkably when the reaction rate became significant. It implies that the diffusion of the solvent is inhibited by skinning at the surface. Applying the Vrentas/Duda free-volume diffusion model to the prediction of diffusivity, the heat and mass transfer in the resin film were analyzed theoretically with a reasonable accuracy.     

Reliability and degradation behaviors of semi-insulating Fe-dopedInP buried heterostructure lasers fabricated by RIE and MOVPE

We clarified the degradation behaviors of semi-insulating buried heterostructure lasers in which mesa structures were fabricated by reactive ion etching (RIE) and then buried in semi-insulating Fe-doped InP grown by metal organic vapor phase epitaxy (MOVPE). The degradation rate and mode correlated with the quality of the buried heterostructure (BH) interface. Based on the correlation, a condition for highly stable semi-insulating Fe-doped InP buried heterostructure (SIBH) lasers was demonstrated and confirmed experimentally and statistically     

Single-photon emission from a single nanoparticle consisting of a single conjugated polymer chain

Single-photon behavior in the emission from a single nanoparticle consisting of a single poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV, molecular weight: 2,600,000 amu) chain has been investigated. Photon correlation measurements of a number of single nanoparticles revealed that the probability of single-photon emission from the single nanoparticles clearly increases, compared with that of single chains embedded in host polymer matrices, poly(methyl methacrylate) (PMMA) and polystyrene (PS). The result suggested that even a single MEH-PPV chain with high molecular weight, which does not exhibit single-photon emission in PMMA and PS, is forced to exhibit single-photon emission by adopting “compact” chain conformation like nanoparticle. Efficient exciton migration and exciton annihilation processes in the compact chain conformation most probably result in the efficient single-photon emission from the single nanoparticle. The present results indicate that multi-quantum systems consisting of a large number of chromophores, such as the MEH-PPV, can be made to behave as single-photon sources by appropriately controlling their size.     

EFFECT OF INTERMITTENT HEATING ON DRYING-INDUCED STRAIN-STRESS OF MOLDED CLAY

Parametric analyses of the strain-stress in the drying process are performed to study the influence of the intermittent drying on the behaviors of drying-induced strain-stress and deformation as well as the drying characteristic. The transient three-dimensional problem of strain-stress and heat and moisture transfer in a slab is solved simultaneously by the finite element method. The dimensionless parameters are introduced to generalize the problem in the conservation equations of heat and moisture transfer. The intermittent drying is modeled by applying periodically smaller and larger Biot numbers to the boundary conditions. The maximum tensile and compressive stresses fluctuate, and fall remarkably during the smaller Biot number period when a slab is heated intermittently. The peak stress of the fluctuation exceeds beyond the case in the continuous healing where the overall drying rate is almost equivalent to that in the intermittent beating, but the reduction of the stresses takes place rapidly in the low heating period.     

HYBRID DRYING OF GRANULAR MATERIALS BY COMBINED RADIATIVE AND CONVECTIVE HEATING

As one of the basic steps of the R&D on hybrid drying by combined radiative and convective heating, drying experiments of a stagnant horizontal wet granular layer heated simultaneously by infrared lamps and hot air were conducted throughout a whole period of the drying. An opaque model, in which the incident radiation is assumed to be absorbed only on the surface of the layer, was introduced to explain experimental trends. Then, the effects of combined heating on drying characteristics of three kinds of samples, a silica sand, a brick and a brown coal were discussed by comparing the experimental data with the calculated results.

The calculated results were found to be in a close agreement with the experimental data obtained on the time behaviors of the drying rate and the temperature distribution in the- layer during not only the preheating and the constant rate periods but also the falling rate period. In the case of the coal layer, however, the falling drying rate different from that in ordinary convective drying had to be considered since it appeared that the radiative heating had an effect to enhance the falling drying rate of the coal owing to some interactions of the coal and water.     

Monolithic integration of InGaAs/InP DFB lasers and InGaAs/InAlAs MQW optical modulators

The first successful monolithic integration of InGaAsP/InP distributed feedback (DFB) lasers and InGaAs/InAlAs multiple quantum well (MQW) optical modulators using LPE (liquid phase epitaxy)/MBE (modlecular beam epitaxy) hybrid growth reported. A 14% light output modulation is observed in this integrated device.     

Novel IV-Group Based Diluted Magnetic Semiconductor: Cr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript>1−</Subscript><Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>

Cr _x Ge_{1? x} (x ～ 0.08) films were grown on GaAs (001) and Ge (001) substrates using molecular beam epitaxy (MBE) method, and their magnetic and transport properties have been studied in the temperature range between 1.8 and 300 K. All of the films exhibited weak paramagnetic behavior. Transport measurements showed that magnetoresistance ratio and the anomalous Hall resistance depend on the Cr concentration x and the kinds of substrate.     

Comparison of coupling characteristics for several spotsize-converter-integrated laser diodes in the 1.3-/spl mu/m-wavelength region

Four types of spotsize-converter-integrated laser diodes (SS-LDs) are numerically compared from the viewpoint of the coupling characteristics to the single-mode fiber in the 1.3-/spl mu/m-wavelength region. The comparison is based on the semivectorial three-dimensional (3-D) finite-difference (FD) beam propagation method (BPM). The SS-LDs investigated here are categorized into a group with vertical tapers and a group with a combination of a lateral taper and a thin-film core. The features of the SS-LDs are clarified.     

Coupling and conversion characteristics of spot-size-converterintegrated laser diodes

The coupling and conversion characteristics of four types of spot-size converter integrated laser diodes (SS-LDs) to a single-mode fiber (SMF) in the 1.3-μm-wavelength region are numerically clarified. The SS-LDs are categorized into types with vertical tapers and types with a combination of a lateral taper and a thin-film core. The eigenmodes are obtained by the finite-element method (FEM). The semivectorial 3-D finite-difference (FD) beam propagation method (BPM) is used to calculate the propagating beams     

3-D semivectorical beam propagation analysis of a spotsize-converter-integrated laser diode in the 1.3-/spl mu/m-wavelength region

Spotsize converters (SSCs), consisting of a lateral taper, thin-film core, and ridge, have been accurately designed to develop spotsize-converted laser diodes (SS-LDs) in the 1.3-/spl mu/m-wavelength region based on the 3-D semivectorial finite-difference beam propagation method (FD-BPM) with nonequidistant discretization. The effects of the structural parameters on the sum of spot-conversion loss and coupling loss between the laser diode eigenmode and single-mode fiber (SMF) eigenmode are clarified. It is shown that a small loss of around 1.5 dB can be realized by introducing nonlinear tapers to these types of SSC's. The calculated results agree well with the measured results.