H. A. a b Khonakdar

Thermal analysis and successive self-nucleation and annealing (SSA) treatment of synthesized bimodal polypropylene (BPP) reactor blends using homogeneous binary metallocene catalyst

AbstractSeveral polypropylene (PP) reactor blends were synthesized using homogenous binary metallocene catalytic systems composed of isospecific (I): rac-Me2Si(2-Me-4-Ph In)2ZrCl2 and oscillating (II): (2-Ph In)2ZrCl2 catalysts. The reactor blends were analyzed using gel permeation chromatography and differential scanning calorimetry. All the blends showed bimodal molecular weight distribution, and the MWs were shifted toward higher values compared with PPs synthesized with each of individual catalysts showing some probable interactions between the two active sites. Self-nucleation and annealing treatment on hexane-insoluble–heptane-soluble parts of the PP reactor blends showed that as the II/I molar ratio increases from 0 to 40 in the binary system, multiplicity of the endotherm peaks increases from 1 to 7, which is indicative of the presence of various lamellar thicknesses in the samples. Wide-angle X-ray scattering studies on the PP reactor blends confirmed that the blends have isotacticities and crystallinities between those of polymers obtained by the individual catalysts.n

On physical and antibacterial properties and drug release behavior of poly(vinyl alcohol) hydrogels: effect of drug loaded chitosan nanoparticles

ABSTRACT This paper deals with influence of chitosan nanoparticles (CNPs) loaded by tetracycline, as a drug, on the physico-mechanical and antibacterial properties as well as drug release behavior of poly(vinyl alcohol), PVA, hydrogels prepared by electron beam irradiation. The formation of spherical chitosan particles in nanoscale size prepared by an ionic gelation method was confirmed by FTIR and UV spectroscopy, and scanning electron microscopy analyses. The drug release kinetic studies from drug loaded chitosan nanoparticles (DLCNPs) at pH = 7.4 revealed a linear and steady release behavior over long period of time. The theoretical analysis of the swelling kinetic data, using Peppas’s model showed that the swelling kinetic is governed by Fickian diffusion for all the prepared hydrogels, however, the water diffusion coefficient, and therefore, the swelling content were lower for the hydrogels loaded with DLCNPs as compared to the ones with the neat drug. In agreement with these results, the hydrogels containing DLCNPs exhibited a more controlled drug release behavior with significantly stronger antibacterial activity. The tensile mechanical properties of the hydrogels not affected by the DLCNPs were found to be suitable for wound dressing applications. GRAPHICAL ABSTRACT

Cavitation in Irradiated and Oriented High-Density Polyethylene Cast Films with Stacked Lamellar Morphology

ABSTRACT Cavitation (void formation) in high-density polyethylene cast films, having a stacked lamellar morphology, subsequent to tensile stretching of both nonirradiated and irradiated films was investigated. With nonirradiated films, the cavitation was not observed in the nonannealed films with lower draw ratios, while a limited number of voids was detected in the films of higher draw ratios. Annealing caused an intensive cavitation, and uniform distribution of cavities was noticed in highly oriented films. It was shown that cross-linking exerted a suppressive influence on cavitation in the annealed and oriented films; and with increasing the irradiation dose, the cavitation was completely eliminated. GRAPHICAL ABSTRACT