Nanocomposites and nanomaterials

The influence of metal oxide nanoparticles on the rheological melt properties of polypropylene/copolyamide blends
Budash Yu. O., Rezanova N. M., Lubska M. V., Plavan V. P.
Kyiv National University of Technology and Design Nemirovich-Danchenko, 2, Kyiv-01011, Ukraine. E-mail: budash.yo@knutd.edu.ua 

A simple and effective method of creating polymeric materials with predetermined characteristics is to mix the individual components and to introduce the substances into the nanostructure. 
The purpose of the work is to study the effect of nanoscale additives of oxides of different metals on the flow patterns of the melt blends of polypropylene/ copolyamide (PP/CPA). Objects of the study: PP/CPA blends of 30/70 wt.%, filled with nanoparticles (NP) of metal oxides: ZnO, Al2O3, TiO2 and mixed ZnO/Al2O3 oxide. The content of additives was 1.0 wt.%. 
The results of the studies showed a significant influence of nanoparticles of oxides of different metals on the macro-rheological characteristics of the PP/CPA melt blends. Judging by the values of the swelling of the extrudates, the elasticity of the melt blends increases, compared to the original PP and CPA, and is 5.1 and (5.7÷7.6) for the bi- and ternary systems, respectively. The sharp increase in the elastic properties of the investigated polymer blends indicates the formation of liquid PP jets in the CPA matrix. For a PP/CPA blends filled with NP mixed oxide, the swelling value is 1.5 times higher than that for the initial blends, indicating the formation of more advanced microfibrillar morphology.
The effective viscosity of the modified composition melts decreases 1.6 and 2.8 times, compared to the η PP and CPA melts, respectively. A significant decrease in η is characteristic of systems in which the dispersed phase polymer forms anisotropic structures in the matrix component. Specific interactions between the functional groups of CPA macromolecules and NP metal oxides structure the melt and increase the viscosity of the nanoscale compositions by (10÷30)%, compared to the binary blends. The nature of the flow of the original and modified compositions is subject to a power law. The degree of deviation from the newtonian flow regime for filled systems is increasing slightly.
The introduction of nanoparticles of all investigated metal oxides contributes to the increase of the deformation ability of melt jets in the tensile field: the value of the maximum degree of drawing increase. The modification effect depends on the type of oxide, with the maximum draw ratio for blends filled with ZnO/Al2O3 nanoparticles 1.5 times higher than the original one. This is due to the fact that anisotropic structures increase the ability of the melt to deform longitudinally.