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Effects of processing on the microstructure, melting behavior, and equilibrium melting temperature of polypropylene
Author(s) -
Tiganis B. E.,
Shanks R. A.,
Long Yu
Publication year - 1996
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19960124)59:4<663::aid-app12>3.0.co;2-r
Subject(s) - differential scanning calorimetry , spherulite (polymer physics) , materials science , crystallization , polypropylene , isothermal process , microstructure , crystal (programming language) , fusion , phase (matter) , enthalpy of fusion , melting point , polymer chemistry , analytical chemistry (journal) , thermodynamics , composite material , chemistry , polymer , organic chemistry , linguistics , philosophy , physics , computer science , programming language
Polypropylene (PP) was extruded and injection‐molded several times to mimic the effect of recycling procedures on PP. Differential scanning calorimetry (DSC) was used to follow crystallization rates under isothermal conditions in a temperature range of 120–150°C. Melting behavior and equilibrium melting temperatures were studied using the Hoffman‐Weeks method of extrapolation. Optical microscopy combined with a hot stage was also used to follow the spherulite microstructure and crystal phase upon recycling of PP. Wide‐angle X‐ray spectroscopy identified the crystal phase at different isothermal crystallization temperatures. Twin melting peaks obtained for PP melting following isothermal crystallization were associated with crystal rearrangement during fusion. PP spherulite size and equilibrium melting temperatures were seen to increase with processing events, whereas reprocessing decreased nuclei density. © 1996 John Wiley & Sons, Inc.