| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 96 === Three different electrospun fibers, sPS, aPS sPS/aPS-U and nylon-6 fibers were obtained by electrospinning first. In this study, we investigated the transcrystallization of polypropyrene (PP) on the as-spun fibers with different diameters and structures.
This research is divided into five parts. First, as-spun sPS fibers with different degree of crystallinity were studied to reveal the crystallinity effects on the PP nucleating ability. Polarized optical microscope (POM) images are used to measure the nucleation rate (I), the nucleation density at saturation (N∞), the maximum temperature for transcrystalline layer (Tmax) to develop, and the interfacial free energy difference function of PP transcrystallization on the fiber. Experimental results show that there is no significant change in PP nucleating ability by changing the sPS fiber crystallinity.
The second part is to study the fiber diameter effects on the PP nucleating ability. The results show that I, N∞, and Tmax are increased with fiber diameter. A lower interfacial free energy difference function is obtained for larger fibers, which means that transcytstallization of PP is easily developed in the thicker fiber. Surface morphology of sPS fibers is revealed by atomic force microscope (AFM), showing that fiber roughness is increased with increasing fiber diameter.
The third part shows that there is no preferential PP nuclei on the aPS fiber surface.
The fourth part is to observe the PP nucleating ability on the sPS/aPS-U (bead-on-string) fiber. The POM images show the presence of PP transcrystallize on the beads but not shown on the string part. We analyze this particular morphology, and conduce that the spherical part is sPS rich phase, and fiber segment is composed of aPS rich phase.
In the last part, the PP nucleating ability on nylon-6 fiber is also examined. Results show that nylon-6 fibers can induce PP transcrystallinity more easily than sPS fibers.
|
|---|
