New approach to morphological control for polypropylene/polyethylene blends via magnetic self-organization

Publication date: 5 March 2017
Source:Materials & Design, Volume 117
Author(s): Yu-Dong Shi, Kai Zhang, Yi-Fu Chen, Jian-Bing Zeng, Ming Wang
Morphological control has been efficiently used to improve the properties of polymer blends/composites. Here we introduce a non-invasive approach to regulate the morphologies of isotactic polypropylene (iPP)/linear low density polyethylene (LLDPE) blends via magnetic self-organization. First, ferric oxide (Fe3O4) particles are added into LLDPE melts to form an LLDPE+Fe3O4 master batch. Second, the master batch is melt-mixed with iPP to form the iPP/(LLDPE+Fe3O4) composites with a random distribution of LLDPE+Fe3O4 droplets. Finally, the randomly distributed Fe3O4 particles self-organize into particle chains in a magnetic field, which induce LLDPE droplets to coalesce with each other to form a strip morphology. The composites with a parallel strip morphology exhibited mechanical enhancement in comparison to the composites with the droplet morphology. For example, the Young's modulus and storage moduli (at −30°C) of the 80/20–10 composites, where the iPP/(LLDPE+Fe3O4) ratio is 80/20, and the content of Fe3O4 particles in LLDPE is 10wt%, with a parallel strip morphology along the tensile direction being 12 and 36% higher than that of the samples with the droplet morphology, respectively. Complex viscosity of the samples with the strip morphology is lower than that of the samples with the droplet morphology because of interfacial slip.

Graphical abstract

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