The FT-IR imaging method has been applied to acquire thousands of infrared spectra at a spatial resolution near the diffraction limit using an IR image sensor. We propose the mathematical procedure to visualize the degree of molecular orientation and the azimuth angle of the orientation axis using the polarized absorbance images measured with a linear polarizer settled at four different angles. It mathematically synthesizes in-plane orientation function that is independent of the direction of the incident polarization and visualizes the molecular orientation and the azimuth angle using an IR imaging sensor. By introducing the azimuth angle image, a small change of the molecular orientation can be detected visually in the early stage of local deformation of the uniaxially drawn process of the polyethylene composite film.

Thermal diffusivity of alkali and silver halide crystals as a function of temperature J. Appl. Phys. 109, 033516 (2011); 10.1063/1.3544444 Thermal conductivity/diffusivity of Nd 3 + doped Gd V O 4 , Y V O 4 , Lu V O 4 , and Y 3 Al 5 O 12 by temperature wave analysisThe heat transport properties of aromatic polyimide thin films have become more important in the use for the electric insulation in the microelectronic devices with highly integrated circuits. The various kinds of measuring methods have been applied to obtain the anisotropic thermal conductivity and thermal diffusivity of thin films, however, if the specimens are soft and transparent, the conventional methodology requires highly advanced technology in preparing the specimens for the measurement and the results obtained vary widely. The purpose of this study is to apply the temperature wave analysis ͑TWA͒ method to measure the thermal diffusivity of thin films and spin-coated layers of aromatic polyimide in the thickness direction at various temperatures. The TWA is an absolute method to determine the thermal diffusivity by using the phase shift of temperature wave. We have performed measurements on the five different chemical structures of aromatic polyimide, including polyimide isoindoloquinazolinedione ͑PIQ͒, pyromellitic dianhydride and 4 , 4Ј-oxydianiline ͑PMDA/ODA͒, 3,3Ј ,4,4Ј,-biphenyltetracarboxylic dianhydride and p-phenylenediamine ͑BPDA/PPDA͒, 3,3Ј ,4,4Ј-biphenyltetracarboxylic dianhydride and 4,4Ј-oxydianiline ͑BPDA/ODA͒, and 3 , 3Ј ,4,4Ј-benzophenonetetracarboxylic dianhydride and 3,3Ј-diaminobenzophenone ͑BTDA/DAB͒. As a result, thermal diffusivity of thin films in a thickness range from 0.1 to 300 m at a temperature range from 10 to 570 K is obtained. The thickness dependence of thermal diffusivity of spin-coated layers of PIQ exhibits a good coincidence with the tendency of molecular anisotropy observed by attenuated total reflection Fourier transform infrared spectroscopy. In the low temperature below 20 K the amorphous PMDA/ ODA film exhibits a substantial increase, which can be understood by considering the phonon mean free path of amorphous systems as first noted by Kittel for inorganic glasses. The glass transition of BTDA/DAB is observed as a rapid decrease of thermal diffusivity. The results indicate the availability of TWA for the present needs of accurate but simple measuring technique to determine the thermal diffusivity of thin polymer films, which is strongly dependent on the chemical and anisotropic structures.

The chemical and the molecular chain orientation image of a banded spherulite of crystalline polymers, poly(l-lactic acid) (PLLA) and poly(3-hydroxybutyrate) (PHB), are visualized using FT-IR imaging with a newly proposed multipolarization calculation method. The vector representation of FT-IR image at different absorption spectral peaks visualizes the magnitude and direction of molecular chain orientation directly in comparison with the retardation and the slow-axis azimuthal images obtained by birefringence imaging. We found for the first time that the wavenumber dependence of in-plane orientation function in the band structure of a PHB spherulite, which is known as a double-band structure originated from a biaxial refractive index ellipsoid. The 15 absorption peaks in the IR spectrum of PHB can be classified into three groups by a different appearance of a band structure in view of the magnitude of molecular chain orientation. The azimuthal image of birefringence also shows the double-band structure; however, the FT-IR azimuthal images of orientation axis indicate the completely different distribution in which there is no band structure at any IR absorption peaks. By contrast, a good correspondence between the azimuthal image of the slow axis of birefringence and the orientation axis of FT-IR is observed in the spherulite of PLLA, which has a uniaxial refractive index ellipsoid. The advanced FT-IR imaging method clarifies the wavenumber-dependent two-types single-band structures of PHB, indicating the local molecular chain orientation along the crystallographic axes in a unit cell.

A complex new magnetic refrigerant, suitable for the ideal Ericsson cycle, has been investigated. Above ∼15 K it is necessary to use ferromagnets as a magnetic refrigerant. However, temperature variation for the magnetic entropy change in a homogeneous ferromagnet is not suitable for the Ericsson cycle. The present paper verifies, from theoretical analysis, that a complex ferromagnetic material, for instance, (ErAl2)0.312(HoAl2)0.198 (Ho0.5Dy0.5Al2)0.490, has the most suitable characteristics for the ideal Ericsson cycle, including two kinds of isomagnetic field processes. On the basis of the above consideration, a sintered layer structural complex has been prepared, composed of three kinds of RAl2.15 layers, where R’s are rare-earth atoms. From specific heat measurements made on this complex, its entropy and entropy change have been determined. It has been concluded that the complex magnetic material is the most hopeful refrigerant for the Ericsson cycle.

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