SAXS study applied to reversibly crosslinked isotactic polypropylene/clay nanocomposites

• Published in: Journal of applied polymer science 2010-09, Vol.117 (6), p.3262-3270
• Main Authors: Bouhelal, S, Cagiao, M.E, Benachour, D, Djellouli, B, Rong, L, Hsiao, B.S, Baltá-Calleja, F.J
• Format: Article
• Language: English
• Subjects: Applied sciences; Chains; Clay (material); clay nanocomposites; Composites; Crosslinking; Diffraction; Exact sciences and technology; Forms of application and semi-finished materials; Isotactic; isotactic polypropylene; Nanocomposites; Nanostructure; Polymer industry, paints, wood; polymorphism; Polypropylenes; reversible crosslinking; Technology of polymers; X-ray scattering
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.32241

A new route based on reversibly crosslinking reactive extrusion is applied for the development of iPP/clay nanocomposites. Analysis of small-angle X-ray scattering (SAXS) reflections of isotactic polypropylene (iPP)/clay nanocomposites, prepared by two different mixing and chemical crosslinking methods (i.e., conventional and in situ), is presented and results are compared with preceding wide-angle X-ray diffraction (WAXD) results. It is shown that the presence of clay significantly affects the value of long spacing in iPP, as well as the coherence length of lamellar stacks. Results show that the size of the coherently diffracting nanodomains decreases in two stages, first rapidly and then slowly as a function of increasing clay content. This can be attributed to the influence of confined iPP lamellae under the effect of rising number of clay particles. The appearance of the γ-crystalline form in the crosslinked iPP/clay nanocomposites is related with the difficulty in chain folding of iPP chains introduced by the chemical crosslinking process, as well as by the presence of clay particles.