In this study, poly(ethylene terephthalate) (PET)/SiO 2 nanocomposites were synthesized by in situ polymerization and melt-spun to fibers. The superfine structure and properties of PET/SiO 2 fibers were studied in detail by means of TEM, DSC, SEM, and a universal tensile machine. According to the TEM, SiO 2 nanoparticles were well dispersed in the PET matrix at a size level of 10-20 nm. The DSC results indicated that the SiO 2 nanoparticles might act as a marked nucleating agent promoting the crystallization of the PET matrix from melt but which inhibited the crystallization from the glassy state, owing to the ''crosslink'' interaction between the PET and SiO 2 nanoparticles. The tensile strength of 5.73 MPa was obtained for the fiber from PET/0.1 wt % SiO 2 , which was 17% higher than that of the pure PET. The fibers were treated with aqueous NaOH. SEM photographs showed that more and deeper pits were introduced onto PET fibers, which provided shortcuts for disperse dye and diffused the reflection to a great extent. According to the K/S values, the color strength of the dyeing increased with increasing SiO 2 content. It is found that the deep dyeability of PET fibers was improved greatly.

In this study, poly(ethylene terephthalate) (PET)/SiO 2 nanocomposites were synthesized by in situ polymerization and melt-spun to fibers. The superfine structure, physical properties, and dyeability of alkaline hydrolyzed PET/SiO 2 nanocomposite fibers were studied. According to the TEM, SiO 2 nanoparticles were well dispersed in the PET matrix at a size level of 10-20 nm. PET/ SiO 2 nanocomposite fibers were treated with aqueous solution of sodium hydroxide and cetyltrimethyl ammonium bromide at 1008C for different time. The differences in the alkaline hydrolysis mechanism between pure PET and PET/SiO 2 nanocomposite fibers were preliminarily investigated, which were evaluated in terms of the weight loss, tensile strength, specific surface area, as well as disperse dye uptake. PET/SiO 2 nanocomposite fibers showed a greater degree of weight loss as compared with that of pure PET fibers. More and tougher superfine structures, such as cracks, craters, and cavities, were introduced, which would facilitate the certain application like deep dyeing.

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Poly(ethylene terephthalate) (PET)/SiO 2 nanocomposites were prepared by in situ polymerization. The dispersion and crystallization behaviors of PET/SiO 2 nanocomposites were characterized by means of transmission electron microscope (TEM), differential scanning calorimeter (DSC), and polarizing light microscope (PLM). TEM measurements show that SiO 2 nanoparticles were well dispersed in the PET matrix at a size of 10 -20 nm. The results of DSC and PLM, such as melt-crystalline temperature, half-time of crystallization and crystallization kinetic constant, suggest that SiO 2 nanoparticles exhibited strong nucleating effects. It was found that SiO 2 nanoparticles could effectively promote the nucleation and crystallization of PET, which may be due to reducing the specific surface free energy for nuclei formation during crystallization and consequently increase the crystallization rate.