Dispersed crystallite and intercrystalline bridge

In the case of crystalline polymers such as high density polyethylene (FiDPE), the effect of orientation on the morphology has been extensively studied [32,48]. The isotropic sample consists of crystalline lamellae (thickness 100-400 A) embedded in an amorphous matrix. Each lamella is composed of a mosaic of crystalline blocks of lateral dimension 100-200 A with boundaries defined by dislocations. The lamellae are randomly oriented and generally arrange themselves end to end in ribbon-like structures which grow out from nucleating centers to form 

for a rough estimate, it is assumed that the expansivity tensor of a composite with fully aligned crystallites can be obtained by the linear interpolation between those of its component phases, i.e. 

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