Tailoring Crystallization in Polypropylene Blends via Nano-Localization

The crystallization characteristics of polypropylene (PP), a commonly utilized polymer in various industries, can be adjusted to address its mechanical limitations. In this study, we explored how factors such as ethylene-octene copolymer (EOC), blend morphology, nanoclay loading, nano-localization, and component ratios influence the crystallization behaviour of PP/EOC across several dimensions, including crystallization kinetics, degree of crystallinity, nucleation state, and crystalline phases. Our findings indicated that incorporating EOC in different ratios can reduce both the degree and rate of PP crystallinity due to the partial miscibility of the components through grafting. Additionally, the impact of nanoclay on the crystallization behaviour of PP was found to depend on the loading level and its localization within the blend. At low nanoparticle concentrations, nanoclay acted as a nucleation agent, enhancing crystallization kinetics irrespective of the blend's microstructure. However, at high nanoclay concentrations (exceeding the rheological percolation threshold), the crystallization kinetics of the blend samples were significantly affected by the type of morphology present. In blends with matrix-dispersed morphologies, elevated nanoclay levels slowed down crystallization kinetics, primarily because PP chains experienced hindrance due to interactions with nanoparticles. Conversely, in blends exhibiting a co-continuous morphology, crystallization kinetics improved due to nano-localization at the interface and a transformation of morphology to a matrix-dispersed state.

کلیدواژه ها:

Crystallization ، Nanocomposite ، Polyolefin ، Ethylene-octene copolymer ، Morphology