Poly spherulite diameter

Spherulites make films and foils opaque when their diameters are greater than half in wavelength of the light and when, in addition, inhomogeneities exist in relation to the density or to the refractive index. Spherulitic poly(ethylene), for example, is opaque, but spherulitic poly(4-methyl-pentene-1) is glass clear (at room temperature), even when the latter has the same number of spherulites with the same dimensions as poly(ethylene). 

A comparison of the degree of crystallinity obtained by gas chromatography for poly(ethylene oxide) of molecular weight 40 000 with those determined by IE spectroscopy and X-ray diffraction yields [183] 74% for the first method when the polymer film thickness was 6.5 X10" cm, 75.9% for the second (film thickness 5.1X10 cm) and 79.1% for the last method. The differences were ascribed to the incomplete development of crystallinity in the films used in gas chromatography and IE s ctroscopy, these films being thinner than the diameter of the spherulites. 

In [320], jump-like creep was studied for two POM semi-crystaUine polymers. Analysis of their polarizing microscope images showed that homoPOM contained predominantly spherulites 1-5 pm in diameter, whereas poly(oxymethylene-co-oxyethylene) (95POM/5POE) sample contained both the same small spherulites and larger ones, up to 25 pm in diameter. It might be supposed that the size of these more dense structural units will be reflected in the character of variation of the creep rate and the values of deformation jumps L. Then the loosely packed inter-spherulite boundaries could be considered presumably as the most probable points for local shear displacements (micro-plasticity). 

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