The thermal stabilities, mechanical properties, and morphologies of nanocomposites of poly(ethylene terephthalate) (PET) with two different organoclays are compared. Dodecyltriphenylphosphoniummontmorillonite (C 12 PPh-MMT) and dodecyltriphenylphosphonium-mica (C 12 PPh-Mica) were used as reinforcing fillers in the fabrication of PET hybrid fibers. The variations of their properties with organoclay content in the polymer matrix and draw ratio (DR) are discussed. Transmission electron microscopy micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nanoscale, although some clay particles are agglomerated. It was also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the PET hybrid fibers. Even polymers with low organoclay contents (1-5 wt%) were found to exhibit much higher strength and modulus values than pure PET. In the case of C 12 PPh-MMT/PET, the values of the tensile mechanical properties of the hybrid fibers were found to decrease linearly with increases in DR from 1 to 16. However, the tensile mechanical properties of the C 12 PPh-Mica hybrid fibers were found to be independent of DR.

A series of nanocomposites of poly(ethylene terephthalate) (PET) with the organoclay dodecyltriphenylphosphonium-mica (C 12 PPh-mica) were synthesized with the in situ polymerization method. PET hybrid fibers with various organoclay concentrations were melt-spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PET hybrid fibers were characterized with differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, electron microscopy, and universal tensile analysis. The organoclay was intercalated in the polymer matrix at all magnification levels, and some of the agglomerated organoclay layers were greater than 50 nm thick. The thermal stabilities and initial tensile moduli of the hybrid fibers increased with an increasing clay content for DR ϭ 1. For DR ϭ 1, the ultimate tensile strengths of the PET hybrid fibers increased with the addition of clay up to a critical clay loading and then decreased above that critical concentration. However, the tensile mechanical properties of the hybrid fibers did not improve with increasing DR.

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Poly(trimethylene terephthalate) (PTT) nanocomposites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2-dimethylhexadecylimidazolium-montmorillonite (IMD-MMT) and dodecyltriphenyl phosphonium-MMT (C 12 PPh-MMT). PTT hybrid fibers with various organoclay contents were melt-spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD-MMT, the clay layers of the C 12 PPh-MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR ¼ 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD-MMT increased slightly whereas those of C 12 PPh-MMT hybrid fibers decreased slightly.

Nanocomposites of poly(butylene terephthalate) (PBT) with the organoclay C 12 PPh-MMT were prepared using in situ intercalation polymerization. Hybrids with various organoclay contents were processed for fiber spinning to examine their thermal behavior, tensile mechanical properties, and morphologies for various draw ratios (DRs). The thermal properties (T g , T m , and T D i ) of the hybrid fibers were found to be better than those of pure PBT fibers and were unchanged by variation of the organoclay loading up to 2 wt %. However, these thermal properties remained unchanged for DRs ranging from 1 to 18. Most clay layers were dispersed homogeneously in the matrix polymer, although some clusters were also detected. The tensile properties of the hybrid fibers increased gradually with increasing C 12 PPh-MMT content at DR ϭ 1. However, the ultimate strengths and initial moduli of the hybrid fibers decreased markedly with increasing DR.