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Melt Mastication of Isotactic Polyproyplene for Improved Thermal and Physical Properties
Author(s) -
Cromer Brian M.,
Coughlin Edward Bryan,
Lesser Alan J.
Publication year - 2020
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.25293
Subject(s) - materials science , composite material , crystallization , lamellar structure , tacticity , polymer , volume fraction , crystal (programming language) , birefringence , modulus , optical microscope , scanning electron microscope , chemical engineering , polymerization , physics , quantum mechanics , computer science , engineering , programming language
Herein a new polymer processing method referred to as Melt‐Mastication (MM) is presented as way to substantially improve the thermal and mechanical properties of Polypropylene (iPP) and other semi‐crystalline polymers. MM is a low temperature mixing technique that subjects molten iPP to chaotic flow under at temperatures between the melting and crystallization temperatures, thereby promoting flow induced crystallization (FIC). The resulting materials demonstrate an unusual crystal morphology that is highly crystalline by thermal calorimetry (57% crystal volume fraction), melts at a temperature 10.3 K higher than conventionally processed iPP, and demonstrates melt memory after annealing at 200°C. The highly crystalline morphology does not show birefringence in polarized optical microscopy and by SEM and AFM appears to be comprised of largely disorganized lamellar crystals, with possible stacked ordering in local (~1 μm) regions. Melt‐Masticated iPP demonstrates improved compressive modulus (+77%), strength (+40%), and strain hardening modulus in uniaxial compression, which are attributed to enhanced crystal volume fraction, lamellar crystal thickness, and network connectivity, respectively. POLYM. ENG. SCI., 60: 380–386, 2019. © 2019 Society of Plastics Engineers