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Investigating the Morphological Variations Due to Processing and Thermomechanical Treatment of Poly(propylene) Using Raman Microscopy
Author(s) -
Sanoria Abhishek,
Damodaran Subin,
Schuster Tobias,
Brüll Robert
Publication year - 2016
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201500412
Subject(s) - crystallinity , raman spectroscopy , materials science , microscopy , spherulite (polymer physics) , welding , polymer , optical microscope , shearing (physics) , composite material , optics , scanning electron microscope , physics
Differences in the Raman spectrum of the α‐ and β‐polymorph of poly(propylene) (PP) have been identified in the form of band shifts distinct for the specific polymorph. A new method has been developed, which can ascertain the presence of the α‐polymorph. These band shifts have been used to profile both the polymorphs and variations in the crystallinity across the whole spherulite have been ascertained by carrying out a spatially resolved profiling of the degree of crystallinity. The crystalline domains in PP have been qualitatively assessed using the band shifts in the Raman spectra. This approach has then been applied to study local variations in the morphology of welds between PP plates, wherein the complex interplay between the heating and cooling patterns as well as the mechanical forces due to shearing gives rise to the development of a different morphological structure in the weld. Using Raman microscopy, a reduction in the crystallinity (≈18%) in the region of the weld seams and sporadic formation of β‐spherulites in the weld core is observed. The methodology developed has been applied to investigate a weld between PP‐H and PP‐R (PP with random ethylene copolymer), to ascertain the variations occurring upon welding in such materials.