Fringed-micellar crystallite

Keller et al. [86, 89,90] proposed the existence of two families of X-ray effects in stretched commercial poly(vinyl chloride) A-crystals with an orientation of the a-axis (i.e. in the direction of the polymer backbone) in the stretch direction and B-crystals with an orientation of the c-axis (i.e. perpendicular to the polymer backbone) in the stretch direction. The B-crystals are smaller and are supposed to form the network junctions (crosslinks) of fringed micellar crystallites, whereas the large A-crystals are supposed to be well developed... 

To And the number of statistical units taking part in a junction, let us consider a simple model junction that binds k chains with f sequential units per chain (Figure 8.1(a)). This model is suitable for the descripAon of thermoreversible gels with junctions formed by fringed-micellar crystallites, but Ands applicaAon to other important types of junctions. 

Fig. 24. Schematic representation of a network structure formed by copolymer molecules consisting of non-crystalline sections and sections which crystallize to form fringed-micellar crystallite junctions.

We must conclude from this set of typical data that the crystallite properties of the gel and that of the lamellae formed in dilute solution are the same. Hence, barring an unusual set of coincidences the basic crystallite characteristic of the gel should be of lamellar form for the linear polyethylenes when crystallized from homogeneous solutions. Thus we have at least one system where the crystaUization elation phenomenon does not involve a fringed micellar structure. 

---