پديد آورندگان :
Pourhossaini Mohammad Reza نويسنده , Vasheghani-Farahani Ebrahim نويسنده , Gholamian Maryam نويسنده , Gholamian Mahmood نويسنده
چكيده لاتين :
Microstructural properties of olefin copolymers (i.e., copolymer composition, sequence distribution, and molecular weight and its dispersity) are key factors, which affect the behaviour of olefin copolymers as viscosity modifiers in engine oil. In this article, the variation procedure and control methods of these specifications are described for the synthesis of olefin copolymers using soluble Ziegler-Natta catalyst in a semibatch reactor. Solution copolymerization of ethylene/propylene was performed using VOeI3-AI2Et3el~ systems. Finally, the synthesized viscosity modifier was characterized by IR, GPe, 1 e NMR, DSe, and XRD techniques and elemental analysis method. Molecular weight was controlled by continuous feed of hydrogen during the reaction and its narrow dispersity was maintained by catalyst specifications and initial saturation of solvent
by monomers. Although catalyst activity varies with time, 13e NMR and IR results demonstrated steady copolymer composition. This was achieved by using a catalyst system
with mostly single active site in a semi-batch polymerization by feeding monomers continuously. Also, it was found that randomness in the microstructure of the copolymer was induced at a specific monomer ratio.
