Small-angle scattering semicrystalline polymers

This two-phase model, which was first put forward in (11), provides an adequate description of the diffraction patterns of the as-spun CPE-1 fibers. One can reasonably anticipate, that, as with most semicrystalline polymers in which the amorphous and crystalline phases coexist, in the case of the two-phase system of the copolyester studied, small-angle scattering should reveal the existence of a well-pronounced periodicity. 

Small-angle X-ray scattering (SAXS) experiments using synchrotron radiation (SR) are performed at present mainly in the areas of real time scattering and anomalous dispersion.1 Typical applications are the study of melting or recrystallisation of semicrystalline polymers [4, 5], phase separation of alloys [6], muscle diffraction and stopped flow experiments on dissolved biopolymers [7, 8]. Anomalous dispersion has been exploited in order to determine partial structure factors in alloys [9] or polymers containing heavy atoms [10],... 

For the purpose of this work, processing includes three steps PVTFA sample preparation, solvolysis, and hydration. PVTFA is a semicrystalline polymer that has not been studied extensively because of its poorly defined crystallinity. Wide-angle X-ray diffraction of unoriented polymer tends to give very diffuse scattering maxima. The polymer exhibited a distinct melting endotherm with a small AH of around 13 cal/g. In the most detailed structural study published, Bohn et al. (14) suggested that the X-ray data indicated a large-pitch helical structure for the chain. PVA, on the other hand, is believed to crystallize in a planar zig-zag conformation (15) with a much more typical AH of fusion of 30 cal/g (16). 

Wignall, G.D., Child, H.R. and Samuels, RJ. (1982) Structural characterization of semicrystalline polymer blends by small-angle neutron scattering. Polymer, 23, 957-964. 

Small angle light scattering (SALS) uses light of wavelength 0.5 pm, so can investigate structures in the range 5-100 pm. Spherulites are structures of semicrystalline polymers which are in this size... 

Crist B (2013) Chapter 3 structure of polycrystalline aggregates. In Piorkowska E, Rutledge G (eds) Handbook of polymer crystallization. Wiley, Hoboken de Rosa C, Auriemma F (2013) Crystals and crystallinity in polymers diffraction analysis of ordered and disordered crystals. Wiley, Hoboken Dettenmaier M, Fischer EW, Stamm M (1980) Calculation of small-angle neutrrai scattering by macromolecules in the semicrystalline state. Colloid Polym Sci 258(3) 343-349 Donald AM, Windle AH, Hanna S (2006) Liquid crystal polymers, 2nd edn. Cambridge University Press, Cambridge... 

---