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BANDE CARATTERISTICHE DELL’ORDINE STRUTTURALE Picchi di regolarità (conformazionale): tipici dell’isomeria trans/gauche. Esempi: 1450 cm -1 (trans) e 1435 cm -1 (gauche) nel trans-1,4-polibutadiene; 975, 1340 e 1470 cm -1 conformero trans del PET. Picchi associati a segmenti di catena stereoregolari. Esempio: picchi a 805, 972, 995 e 1100 cm -1 caratteristici della conformazione ad elica dell’i-PP. La lunghezza critica di sequenza (CSL) Picchi di cristallinità, dovuti alle interazioni catena-catena che hanno luogo nella struttura cristallina. Esempio tipico: doppietto 720-730 del PE (CH 2 rocking )
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sample from source to detector IR beam I0I0 I Difference spectroscopy Beer-Lambert law Additivity Physical meaning of the K factors For a two-phase semicrystalline polymer Beer-Lambert law
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POLIETILENE HD
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POLISTIRENE SINDIOTATTICO am ’’ diff am ’’ diff am ’’ diff
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INTENSITA’ DELLE BANDE RAMAN STOKES ANTI-STOKES
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Bulk sulfonation of syndiotactic polystyrene ( -form): Selective surface modification of a polystyrene film SIDE VIEW TOP VIEW
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FT-Raman spectra in the 1800 – 200 cm-1 range of: A) the parent sPS film ( -form); B) sulfonated film with SD = 14.2; C) sulfonated film with SD = 17.0. Calibration curves as a function of the sulfonation degree The ratio as a function of the crystallinity degree FT-Raman spectra in the 3700 – 200 cm-1 range of: A) amorphous sPS film; B) parent sPS film ( -form). Residual concentration of monomers located into helical sequences with CSL 8 -12 (curve A) and CSL 2 – 5 (curve B) as a function of the sulfonation degree.
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Raman image of the fracture surface of the sPS film Micrograph in the visible range of the fracture surface of the sPS film ( form) Depth profile of the sulfonation degree (SD) of a -form sPS film Depth profile in terms of the Residual Sequence concentration (m 8 – 12, left Y-axis) and of crystallinity degree (right Y- axis) for the -form sPS film
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