Abstract
The effect of maleic-anhydride-grafted polypropylene compatibilizer on the crystallization behavior of two isotactic polypropylene homopolymers is experimentally investigated under both quiescent and shear flow conditions. A traditional combination of optical microscopy and calorimetric techniques is used to quantify crystal nucleation and growth rates and suggests a minute increase in nucleation density when the compatibilizer is added. The flow properties of these systems are assessed by means of oscillatory shear rheometry. The altered flow characteristics can be explained based on the molecular weight distribution of the individual blend components, and no influence of maleic anhydride incorporation on the rheological properties is found. While the addition of a small amount of this compatibilizer thus leads to only a slight acceleration of the crystallization kinetics in quiescent conditions, it markedly enhances the crystallization rate when a mild (and strong) shear flow is applied. In the latter case, the resulting morphology and crystal modification are considerably different as compared to crystallization conditions without the presence of flow; in addition to having significantly faster flow-induced crystallization kinetics (I), when the system contains maleic anhydride compatibilization, the formation of oriented structures is hindered (II), and the appearance of the β-modification is suppressed (III) with respect to the homopolymers, which in turn affects the mechanical properties of the material. This result highlights the importance of understanding the crystallization kinetics under processing relevant conditions in order to get a step closer toward full control over the crystallizing microstructure and the subsequent mechanical performance of polyolefin-based composites.
| Original language | English |
|---|---|
| Pages (from-to) | 5278-5289 |
| Number of pages | 12 |
| Journal | Macromolecules |
| Volume | 56 |
| Issue number | 14 |
| DOIs | |
| Publication status | Published - 25 Jul 2023 |
Bibliographical note
Funding Information:This research forms part of the research program of DPI, Project #815 PROFIT. Combined SAXS/WAXD single-shot experiments were performed at the BL11 NCD-SWEET beamline at ALBA Synchrotron with the collaboration of ALBA staff. In situ shear-cell experiments were performed on beamline BM26 at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. The authors are grateful to all DUBBLE staff for providing assistance in using beamline BM26. In addition, the authors thank Bjorn Tuerlings from PTG/e for his assistance with compounding the materials, Jan-Hendrik Arndt (Fraunhofer) for performing the GPC-IR6 measurement on the compatibilizer, and Markus Gahleitner (Borealis) for his assistance in other GPC measurements.
Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society