Materials Science World Congress

Rheology of Polymers is the study of the flowing and deforming behavior of polymeric materials subjected to forces. Obtaining the rheological properties of polymers is crucial to the evaluation of how these materials behave in processing and, finally in their intended use. Polymers have complex rheological properties since they are normally made of rather long chains of molecules and react differently to stress and strain as compared to simple fluids such as water or oil.

Polymers can behave both viscously when under stress and elastically, returning to their original shape after the removal of the stress, one of the principal features of polymer rheology - a characteristic property called viscoelasticity. This allows polymers to behave, on one hand, like viscous liquids and to flow under stress and, on the other hand, like elastic solids which return to their original shape when the stress is removed. In reality, it is this duality of behavior which justifies some important processes, such as extrusion and melding, or fiber spinning.

The viscosity of polymers depends generally on temperature and molecular weight. Polymers belong either to Newtonian fluids or are classified to be non-Newtonian fluids, which account for most polymers whose viscosity varies with the applied shear rate. Under conditions involving high shear- for example, during injection many polymers exhibit shear thinning, in which the viscosity of the polymer decreases with increasing shear.

Rheology thus plays a significant role in the behavior of polymer melts and polymer solutions. Polymer melts, as used in plastic manufacturing, should be flowable at the production stage but their mechanical integrity should remain intact after cooling. Understanding the interaction and entanglement of polymer chains with each other while it is underflow is very crucial to optimizing the processing conditions so as to increase the strength and flexibility of materials.

Summarily, the rheology of polymers is that scientific study that impacts and influences the designs and manufacturing concerns of polymer products. It actually helps understand how these materials behave during processing and assists engineers and scientists in fine-tuning processes for some of the high-performance products across industries like packaging, automotive, and healthcare.