A Journey along the Extruder with Polystyrene:C-60 Nanocomposites: Convergence of Feeding Formulations into a Similar Nanomorphology

• Type: Article in International Scientific Journal
• Date: 2017

Authors

Gaspar, H (Author) Other; Teixeira, P (Author) Other; Santos, R (Author) Other; Fernandes, L (Author) Other; Hilliou, L (Author) Other; Weir, MP (Author) Other; Parnell, AJ (Author) Other; Abrams, KJ (Author) Other; Hill, CJ (Author) Other; Bouwman, WG (Author) Other; Parnell, SR (Author) Other; King, SM (Author) Other; Clarke, N (Author) Other; Covas, JA (Author) Other; Bernardo, G (Author) FEUP

Journal

Title: Macromolecules

Vol. 50

Pages: 3301-3312

ISSN: 0024-9297

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 2 Citations

Scopus - 5 Citations

Other information

Authenticus ID: P-00M-R54

DOI: 10.1021/acs.macromol.6b02283

Abstract (EN): We investigated the effect of the feeding formulation (premixed powders of pure components versus solvent-blended mixture) of polystyrene-C-60 composites on the dispersion and reagglomeration phenomena developing along the barrel of a twin-screw extruder. The dispersion of C-60 in the PS matrix is studied over different length scales using a combination of optical microscopy, spin-echo small-angle neutron scattering (SESANS), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS). When a solvent-blended mixture is used as the feeding formulation, the inlet material contains essentially molecularly dispersed C-60 as revealed by the nanodomains with very small phase contrast. However, C-60 reagglomeration occurs along the extruder, creating a morphology still containing only nanodomains but with much higher phase contrast. In the case of mixed powders, the material evolves from the initial macroscopic mixture of pure polystyrene and C-60 into a composite simultaneously containing micro- and nanoaggregates of C-60 as well as C-60 molecularly dispersed in the matrix. Our results show that the two different initial feeding formulations with widely different initial morphologies converge along the extruder, through opposite morphological pathways, into a similar final nanomorphology which is dictated by the interplay between the thermodynamics of the system and the flow. Correlations between the morphological evolution along the extruder and the thermorheological properties of the composites are identified.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12