Poly(L-lactic acid) (PLLA) intercalated nanocomposite films containing 1, 2, 5, and 10% organically modified montmorillonite (OMMT) have been synthesized by the solvent casting approach. The thermal characteristics, isothermal cold crystallization kinetics, and structural changes of neat PLLA and its nanocomposites during annealing were studied by using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. DSC observation showed that melting temperature and final crystallinity were not affected significantly with OMMT loading. PLLA films with increasing OMMT content exhibited higher crystallization rates than neat PLLA during annealing and suggested that the silicate platelets act as a nucleation agent during annealing. The effect of OMMT content on the isothermal crystallization kinetics of PLLA was analyzed using the Avrami equation. An Avrami constant of 1-2 was observed, suggesting that crystallization proceeds through one-dimensional growth with heterogeneous nucleation. FTIR investigation showed a band at 922 cm(-1) at all T(a), and no band at 908 cm(-1) suggested that all samples form α crystal regardless of OMMT content or T(a).

A study of polyethylene terephthalate (PET) and spectra fabric's ultrasonic sealing (welding) potential was conducted using both continuous and discontinuous ultrasonic welding machines. The effects of two important welding parameters such as weld pressure and weld time were investigated on the fabric's bond strength. Depending on the thermal property of the polymer, a certain level of temperature rise during sealing is required to soften the fibers, to facilitate the development of rows of welding points between the fabric layers. This happens under the compaction due to weld pressure. The gaps between the points are so narrow that the rows appear to be a complete sealing of the layers. Excessive melting under weld pressure, to create melt bonding caused polymer degradation and poor bond strength. Scanning Electron Microcopy images and the temperature measurements at the fabric's interface were used to examine the bond locations of the fabric. Differential Scanning Calorimetry analyses of PET and spectra fabrics have been used to examine the thermal behavior of the ultrasonic sealed material. Adequate seam strength was achieved under certain conditions of sealing for both the fabrics using both continuous and discontinuous methods of operation.

Poly(amidoamine) (PAMAM) (G3) dendrimer was modified into quaternary ammonium salts using tertiary amines with different chain lengths: dimethyldodecyl amine, dimethylhexyl amine, and dimethylbutyl amine using an efficient synthetic route. The antimicrobial activity of these dendrimer ammonium salts against Staphylococcus and E-coli bacteria was examined using the disc diffusion method. It was found that quaternary ammonium salt prepared with the dimethyldodecyl amine exhibits antimicrobial efficacy against Staphalococus and E.coli bacteria.

Poly(l-lactic acid) (PLA) filaments were spun by melt-spinning at 500 and 1850 mm Ϫ1 , and further drawn and heat-set to modify the morphology of these PLA filaments. PLA yarns were characterized by wide-angle Xray diffraction (WAXD) and sonic method. WAXD reveals that PLA yarns spun at 500 mm Ϫ1 are almost amorphous while the PLA filaments spun at 1850 mm Ϫ1 have about 6% crystallinity. This is different from PET filaments spun at the same speed that have almost no crystallinity. Both drawnand heat-set PLA filaments showed much higher crystallinity (60%) than do as-spun fibers produced at 500 and 1850 mm Ϫ1 speed, which is also higher than the usual heat-set PET yarns. It appears that crystalline orientation rapidly reaches a value in the order of 0.95 at 1850 mm Ϫ1 and that drawn-and heat-set yarns have almost the same crystalline orientation values. Molecular orientation is relatively low for as-spun PLA yarn, and molecular orientation increased to ϳ0.5 after drawing or heat-setting or both.