Effect of heat-treatment on stretch of poly(trimethylene terephthalate) woven fabric

The properties of a woven fabric made of poly(trimethylene terephthalate) (PTT) were investigated. The PTT fabric of draw textured yarn (DTY) showed excellent stretch as good as a fabric containing spandex. However, the unique stretch of the PTT fabric reduced dramatically by simple heat-treatment even at as low as 80 °C. To understand the phenomenon, the crimp rigidity of the DTY was observed by SEM. It was found that the drastic reduction of stretch was caused by irreversible uncrimping of PTT DTY after heat-treatment. Conclusively, it is of importance to optimize the texturing conditions for PTT DTY to make the crimp more stable.     

Morphology and properties of polyacrylonitrile/single wall carbon nanotube composite films

Composite films were prepared by casting the solution of polyacrylonitrile (PAN) and single wall nanotube (SWNT) in DMF subsequent to sonication. The SWNTs in the films are well dispersed as ropes with 20–30 nm thickness. Moreover, AFM surface image of the composite film displays an interwoven fibrous structure of nanotubes which may give rise to conductive passways and lead to high conductivity. The polarized Raman spectroscopy is an ideal characterization technique for identification and the orientation study of SWNT. The well-defined G-peak intensity at 1580 cm⁻¹ shows a dependency on the draw ratio under cross-Nicol. The degree of nanotube orientation in the drawn film was measurable from the sine curve obtained by rotating the drawn film on the plane of cross-Nicol of polarized Raman microscope. The threshold loading of SWNT for electrical conductivity in PAN is found to be lower than 1 wt% in the composite film. The electrical conductivity of the SWNT/PAN composite film decreased with increasing of draw ratio due to the collapse of the interwoven fibrous network of the nanotubes with uniaxial orientation.