Figure 1

The atomistic model for PP matrix. An isotactic (a) and an atactic (b) segment of a PP chain. A single PP chain (c) taken out of an amorphous PP matrix (d). The mass density of the amorphous PP matrix ρ = 0.9 g/cc at room temperature. Carbon atoms are grey and hydrogen atoms are white. The BIOVIA Materials Studio 2020 VERNO 20.1.0.2728 (https://www.3ds.com/products-services/biovia/products/molecular-modeling-simulation/biovia-materials-studio) was used to create the drawings in the figure.