Novel approach to tune mechanics of β-nucleation agent nucleated polypropylene: Role of oriented β spherulite

In this study, a novel approach has been developed to introduce orientation to bundle-like β spherulite in iPP samples. The addition of UHMWPE phase, which plays the role of maintaining orientation of iPP chains, into β-nucleation agent nucleated iPP samples leads to the formation of oriented β spherulite in the inner region of injection molded samples. Accordingly, both the tensile strength and impact strength of the sample have been improved. It proves that the arrangement of crystallites is another important factor to determine the toughness in addition to β-crystal content, especially when the content is relatively high. Based on the investigated results, a schematic model about the formation of orientated β crystals via the addition of UHMWPE is proposed. Itʹs the first time that oriented β spherulite is observed and investigated. Our study suggested an alternative approach to achieve good mechanics in polypropylene via introducing orientation to β spherulite.