Hier finden Sie wissenschaftliche Publikationen aus den Fraunhofer-Instituten.

Investigating the morphological variations due to processing and thermomechanical treatment of poly(propylene) using raman microscopy

: Sanoria, A.; Damodaran, S.; Schuster, T.; Brüll, R.


Macromolecular chemistry and physics 217 (2016), Nr.9, S.1037-1046
ISSN: 1022-1352
Fraunhofer LBF ()

Differences in the Raman spectrum of the alpha- and beta-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 alpha-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 (approximate to 18%) in the region of the weld seams and sporadic formation of beta-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.