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Feasibility study on titanium‐catalyzed polyester for the preparation of high‐strength industrial yarns

AbstractIn order to overcome the environmental pollution or personal injury caused by precipitation of heavy metal ions during post‐processing and application of antimony‐catalyzed polyester industrial yarns, the titanium catalyst was used to prepare polyethylene terephthalate (PET) with high molecular weight, and then the titanium‐ catalyzed PET properties related to spinning kinetics were investigated as a basis for designing the drying, melting, spinning and extrusion, cooling, hot stretching and heat‐ setting process parameters. Compared with the spinning process of antimony‐catalyzed polyester of similar molecular weight, based on the lower melting point and melt viscosity of titanium‐catalyzed PET, the spinning temperature was lowered by about 5°C to reduce the thermal degradation of PET during extrusion, and the hot stretching speed and temperature were appropriately lowered based on the characteristics of low crystallization temperature and high crystallization rate in the heating process so that a product with a breaking strength of 8.29 cN/dtex was developed on an industrial device successfully. Titanium‐catalyzed high‐strength polyester industrial yarns, the structure and properties of crystal orientation, lamellar thickness, strength and elongation at break were comparable with those of antimony‐catalyzed polyester industrial yarns.

Metal nanoparticles decorated PET/PET-TiO2 bi-component filaments by photocatalytic deposition

Gold, silver, and platinum nanoparticles were immobilized on the surface of TiO2 in the sheath part of bi-component filaments. The processes involved include the spinning process used to prepare polyethylene terephthalate (PET)/PET-TiO2 bi-component filaments and the photocatalytic deposition process of gold, silver and platinum nanoparticles. The core part and the sheath part consist of virgin PET and 4 wt.% of TiO2 compounded PET, respectively. The sheath: core ratio of the filament was 50:50. For the photo-deposition of metal nanoparticles, adsorption of the metal ions on the surface of the fabrics was performed by immersing them in AgNO3, HAuCl4, and H2PtCl6 aqueous solutions, with simultaneous addition of methanol as a sacrificial agent. Photo-deposition was then carried out under UV light with an irradiation time of 60 seconds. The structural and antibacterial properties of the bi-component filaments were characterized. The nano-sized noble metal particles in a polka dot form were observed around the surface of the TiO2 particles in sheath region of bi-component filaments after photocatalytic deposition. Ag, Au, and Pt metal photo-deposited fabrics showed excellent antimicrobial effect against the two types of bacteria Staphylococcus aureus and Klebsiella pneumoniae under dark conditions.

Thermal, mechanical, and barrier properties of polyethylene terephthalate-platelet nanocomposites prepared by in situ polymerization

This study used in situ polymerization to prepare polyethylene terephthalate (PET) nanocomposites incorporating Ethoquad-modified montmorillonite (eMMT), unmodified hectorite (HCT), or phenyl hectorite (phHCT) particles to study the impact of platelet surface chemistry and loading on thermal, mechanical, and gas barrier properties. eMMT platelets reduced the PET crystallization rate without altering the ultimate degree of crystallinity. In contrast, HCT and phHCT platelets accelerated the polymer's crystallization rate and increased its crystallinity. DMA results for thermally-quenched samples showed that as T increased past glass transition temperature (Tg), HCT and phHCT nanocomposites (and control PET) manifested precipitous drops in G′ followed by increasing G′ due to cold crystallization; in contrast, eMMT nanocomposites had much higher G′ values around Tg. This provides direct evidence of eMMT reinforcement in thermally-quenched eMMT nanocomposites. These results suggest that eMMT has a strong, favorable interaction with PET, possibly through Ethoquad-PET entanglement. HCT and phHCT have a fundamentally different interaction with PET that increases crystallization rate and Tg by 11 to 17°C. Water barrier improvement in eMMT nanocomposites agrees with previously published oxygen barrier results and can be rationalized in terms of a tortuous path gas barrier model. POLYM. ENG. SCI., 52:1888–1902, 2012. © 2012 Society of Plastics Engineers