Modeling of Semicrystalline Polymer and Related Heterogeneous Materials

Personnel: Vaibhaw Kumar, Nikolaos Lempesis, Jun Mo Kim

It is well known that polymer melts never crystallize completely. Instead, one finds a semicrystalline phase characterized by crystalline domains interdispersed into non-crystalline, amorphous regions. It is believed that presence of entanglements as well as bridge chains in the interlamellar phase (as shown in figure) play a crucial role in determining the mechanical properties of the semicrystalline polymers.

We utilize efficient molecular simulation strategies to study the important properties of semicrystalline polymers. Over the past years, we have developed a semi crystalline model which allows us to capture the thermodynamic and mechanical properties of such materials accurately (see publication list). Recently, we have focused on the plastic deformation of the interlamellar phase employing Monte Carlo, molecular dynamics simulations and primitive path analysis (PPA).

A change in the polymer chain chemistry or topology is expected to cause a drastic change in the properties of the resulting semicrystalline materials, although to what extent is relatively less known. We are currently investigating this issue by looking at structure-property relationships of polymers having more complex chemistry, such as linear segmented polyurethanes and branched polymers.