DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.04.3
Published: 02 January 2015 

Abstract: Copolymerization reactions of ethylene with three α-olefins, 1-hexene, 1-octene and 1-decene, were carried out with a new post-metallocene catalyst based on Ti complex with a bidentate saligenin-type ligand I and two co catalysts, MAO and a combination of AlEt₂Cl and MgBu₂. Ability of the I - AlEt₂Cl - MgBu₂ system to copolymerize α-olefins with ethylene is far superior to that of the I - MAO system. Reactivity of α-olefins in copolymerization reactions with ethylene decreases in the sequence: 1-hexene>1-octene>1-decene. Both catalyst systems, I - MAO and I - AlEt₂Cl - MgBu₂, contain several populations of active centers that greatly differs both in the average molecular weights and in composition of the copolymer molecules they produce. Active centers in both catalytic systems show significant tendency to alternate monomer units in copolymer chains.

Flame Retardant and Mechanical Properties of Modified Paper Using Inorganic Salts for Packaging Applications
Pages 227-236
Ahmed M. Youssef, Ola A. Mohamed, M. El-Samahy, Amal H. Abd-El Kaderand Luhac Pichtec

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.04.4

Published: 02 January 2015 

Abstract: The paper sheet prepared from unbleached rice straw containing different concentration of inorganic salts, that work as flame retardant additives (Lithium hydroxide one hydrate (LiOH.1H₂O), Magnesium hydroxide (Mg (OH)₂. 15H₂O), aluminum sulphate (Al₂(SO₄)₃) and calcium carbonate (CaCO₃)) were investigated using horizontal burning test against flame retardant. Also, the prepared paper sheets were characterized using scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and Infrared spectroscopy (IR). Furthermore, the water absorption was determined. In addition, the mechanical properties (breaking length, tear factor and burst factor) of the prepared paper sheet were evaluated. Correspondingly, the physical (structure and mechanical) properties of the prepared paper sheet were enhanced in terms of tensile, tear factor and water absorption. Also, delaying firing process will help in protecting the materials from burning, saving many of economic effect. So the prepared paper sheet can be used for different industrial applications especially in packaging applications.

Comparative Degradation of LDPE, HDPE and HMHDPE under Different Soil Conditions
Pages 178-183
Mohan K.R. Konduri and Venkata Reddy Bogolu

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.03.5

Published: 06 November 2014

Abstract: The Present work includes, degradation of polyethylene under different environmental conditions to know the effect of physical, chemical and biological factors prevailing in those conditions on degradation of polyethylene. Plastic films viz., Low density polyethylene (LDPE), High density polyethylene (HDPE) and High molecular weight high density polyethylene (HMHDPE) each were incubated in three different conditions viz., black soil, sandy soil and red soil for a period of 3 months. The changes in the properties of plastic films after incubation was studied by change in the weight of the plastic film and mechanical parameters like tensile strength, breaking load and percentage of elongation. Among all the plastic films HDPE was found to be highly susceptible with 33% weight loss and 40% reduction in percentage of elongation compared to LDPE with 26% weight loss and 34 % reduction in percentage of elongation in black soil. Whereas HMHDPE found to be highly resistant in all the soils with no significant weight loss and percentage of elongation (15%). None of the plastic films had shown degradation in sandy soil even after incubation for 3 months. FTIR spectroscopy results showed that HDPE film incubated in black soil had undergone extensive degradation when compared with un incubated HDPE film.

Structure of Crystallizable Polymer Solutions
Pages 142-148
Vitaly J. Klenin and Irina V. Fedusenko

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.03.1

Published: 20 October 2014

Abstract: Visually transparent solutions of crystallizable polymers in wide concentration and temperature ranges contain supramolecular particles which are fragments of the most perfect crystallites of condensed polymer. Though the fraction of these particles is usually with in 0.001-0.1wt % of the total polymer, their presence in a solution of macromolecules severely affects its physicochemical and technological properties (performance) and complicates (or even does not allow) the application of structurally-sensitive research techniques (e.g. lights cattering, dynamic birefringence, etc.). The parameters of the first-level supramolecular particles (just after visual dissolution) depend on the conditions of dissolution, storage, and the preliminary treatment temperature of the polymer. In wide polymer concentration and temperature ranges, a second level of the supramolecular particles ensemble is formed, with characteristic features of crystallization. From the formation rate of the second-level supramolecular particles, a microliquidus curve for them can be plotted. The paper presents data for the poly (vinyl alcohol) + water system which lack the area of liquid-liquid phase separation. Supramolecular particles parameters (average sizes, numerical and mass-volume concentration) were determined by means of the turbidity spectrum method.

Characterization of Phosphate Glass Reinforced Gelatin Blend Bioactive Composite Films
Pages 149-156
Kamol Dey, Poonam Alamgir, Shahnaz Parvin, Gulshana Mohol,Wafa Tonny, Mubarak A. Khan and Ruhul A. Khan

DOI: http://dx.doi.org/10.6000/1929-5995.2014.03.03.2

Published: 20 October 2014

Abstract: Bioactive composite films were prepared using bioresorbable phosphate glass powder and biodegradable polymer gelatin (G) through solution casting process. Biocompatible monomer, 2-hydroxyethyl methacrylate (HEMA) was used as the cross-linking agent and bioresorbable phosphate glass (PG) powder was used as reinforcement filler. The composite films were obtained at various ratios of G, PG and HEMA. The PG modified gelatin composite (PG/G) film was fabricated at a weight ratio of 12:88 while HEMA modified gelatin composite (HEMA/G) film at 50:50 ratio. On the other hand, hybrid gelatin composite film, containing both PG and HEMA, was obtained using a G/PG/HEMA ratio of 44:12:44. Incorporation of PG improved the mechanical properties of the composite films. Morphological property of the composite films was investigated by stereo microscope and it revealed that the composite films were porous in nature. The thermal behaviour of the films was studied using thermogravimetric analysis. Water uptake of the films was also performed.