Mother lamellae

Before joining the longitudinal wall of the mother cell, the cell plate becomes weakly birefringent, and two narrow, bright layers can be observed on both sides of the central lamella. The growing cell-plate thus consists of three layers already, namely, the middle lamella in the center and tiie two primary walls of fiiture daughter cells that are being developed as the outer layers. The formation of cell plate is shown in Fig. 19. 

In the case of the sample iPP3 that crystallizes in mixture of a and y forms forming bundle-like entities (Fig. 11.5b, e), the lateral structure of these entities is due to the lateral growth of the y form on the mother a form lamellae (Scheme 11.2c). In fact, the angle between the polymer chains in the y form and... 

First set of values refers to crystallization under quiescent conditions. CNTs nucleated iPP crystals which further nucleated secondary crystallites (mother-daughter lamellae). Second set of values show Avrami exponents for crystalhzation during a step shear of 20 s for 5 s. 

Of particular importance to steel making is the eutectoid point at 727°C 0.76 wt% C. When austenite of this composition is cooled to this temperature, it undergoes euctectoid reaction y a + FeaC. Further cooling produces lamellas of alternating a-Fe and cementite called pearlite because its appearance resembles mother-of-pearl. The spacing of the lamella can be controlled by the cooling rate as discussed in Chapter 12. 

Recrystallization in the stretched state results in the formation of a crystalline network that prevents contraction of the oriented crystalline structure during strain recovery, and thereby freezes the orientation in the elastic film. The data suggests that recrystallization is possibly in the form of epitaxial crystallization of a -PP (daughter) lamellae on top of oriented a-PP (mother) fibrillar crystals. The origin and nature of the orientation of the y-PP needs explanation, and is currently under investigation. 

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