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Molecular Orientation and Dielectric Anisotropy in Polyimide Films As Determined by the Microwave Method

“…Recently, we have developed a new approach, called the microwave method, − instead of methods such as X-ray diffraction, infrared dichroism, and mechanical breaking strength. The microwave method makes it possible to measure quickly and accurately the molecular or fiber orientation and the high-frequency complex dielectric constant of sheet materials without contact.…”

“…The microwave method makes it possible to measure quickly and accurately the molecular or fiber orientation and the high-frequency complex dielectric constant of sheet materials without contact. It has been applied to paper sheets, ,,, polymer films, ,,− ,− blood vessels, cow skins, , and nonwoven fabrics …”

“…The microwave method makes it possible to measure quickly and accurately the molecular or fiber orientation and the high-frequency complex dielectric constant of sheet materials without contact. It has been applied to paper sheets, 5,6,11,12 polymer films, 7,9,[13][14][15][18][19][20][21][22] blood vessels, 10 cow skins, 16,17 and nonwoven fabrics. 8 The present paper uses this method to estimate the molecular orientation and the microwave dielectric anisotropy in polyimide films and compares the result with those obtained through the measurements of mechanical breaking strength and polarized infrared absorbance.…”

Effects of Annealing upon Molecular Orientation and Microwave Dielectric Anisotropy in Polyimide Films

“…The annealing also makes the degree of attenuation in microwaves decrease, as expressed by eq 9. Correspondingly, the value of F decreased from 4.038828 to 4.038529 GHz and then the film thickness increased slightly 23 within an error of one micrometer. These facts are worth noting.…”

“…It was applied to the paper sheets, 8 -11 polymer films such as poly(ethylene terephthalate) (PET) and poly(vinylidene fluoride), 12 -2 0 human blood vessels, 21 cow skins, 22 and nonwoven fabrics. 23 In a previous paper, 24 we reported the molecular orientation of polyimide films determined by the microwave method, and compared the results with those by the mechanical and infrared methods.The present paper describes effects of annealing upon the molecular orientation and the microwave dielectric anisotropy in polyimide films and compares the results with the thermal shrinkage. …”