نتایج جستجو برای: polyolefins
تعداد نتایج: 352 فیلتر نتایج به سال:
Polyethylene (PE) is the most common group of thermoplastic polymers due to its low cost and versatile physical properties. PE is blended with polypropylene (PP) to improve physical properties, such as low temperature impact performance. The composition of these blends is important with regard to performance, and the correct mixing of the pure homopolymers (PE and PP) can eliminate the need for...
Introduction There have been numerous investigations of the structure and organization of polythiophene films and the structural changes that occur during the thermochromic transition. The investigations have primarily focused on the behavior of these materials as pure films or in solution. However, the utilization of conjugated polymers in many electronic applications requires them to be dispe...
A semiempirical epitaxial model has been derived which correlates and interrelates the surface free energy, ultrastructural morphology, surface charge, surface chemistry, and surface molecular motions of a model triblock copolymer to thrombogenesis. This paper addresses the aspect of: (1) ultrastructure order versus disorder, (2) primary and secondary molecular motions, (3) surface and side cha...
Plastic wastes, lube oils and coal-tar are evaluated, individually and combined, as additives to coal blends for the production of blast-furnace coke. The effects of adding 2 wt% of potential additives or their mixtures (50:50 w/w) on the coking capacity of coal, the pressure generated during the coking process and the coke quality parameters were evaluated. Using a combination of polyolefin wa...
In this work, we studied propylene polymerization using some α-diimine palladium catalysts with systematically varied ligand sterics. In propylene polymerization, the ligand steric effect exhibits significant variations on the catalytic activity, polymer molecular weight, and branching density. However, the regio control for the polymer microstructure is poor. Furthermore, copolymerization of 1...
Catalytic cyclopropanation of commercial 1,2or 1,4cis-polybutadiene, respectively, with ethyl diazoacetate catalyzed by [TpCu(NCMe)] (Tp 1⁄4 hydrotris(3,4,5-tribromo-1-pyrazolyl)borate) at room temperature afforded high molecular weight (Mn > 10 5 mol ) side-chain or main-chain, respectively, carboxyethyl cyclopropyl-substituted polymers with variable and controlled degrees of functionalization...
The ability to predict polymer properties from a knowledge of the chemical architecture of the chains is one of the main goals of polymer science, and achievement of this can be very useful in the development of new polymeric materials. In this paper the connection between dimensions of polyolefin chains and some of their most fundamental properties, such as the degree of entanglement and misci...
In previous part of this work factors influencing the thermal stability of polymer nanocomposite materials were indicated, such as chemical constitution of organic modifier, filler content, nanocomposites’ structure and the processing-dependent degree of homogenization of nanofiller, were presented. In this part the basic changes in thermal behaviour of different polymeric matrixes (e.g. polyol...
Marine and inland pollution by non-degradable plastic bags and other plastic articles is a topic of great concern. Natural degradation processes based on oxidation of plastic pollutants could possibly contribute to limit the extent of pollution. Thermal degradation of polyolefins in the absence of light by non-polluting pro-oxidants has not been presented before. In this study, we show that two...
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