Fibrillation, rubber network

Figure 5. Rubber particles with crazes in HIPS. The rubber particles are strongly elongated by cavitation and fibrillation in the rubber network around PS inclusions (HVEM image). The deformation direction is vertical.

A critical parameter of this mechanism is the thickness of the rubber network layers, which must be around a few tens of nanometers. Only a thin-walled network like this can generate a triaxial (hydrostatic) stress state that is high enough to reach the yield stress of PVC, or alternatively, the thin rubber layer PVC can be separated into fibrils, transferring stresses onto the PVC particles. 

The elastomers exhibited rubber-like behavior. From an examination of electron photomicrographs of cross sections of the elastomers, the fibrillar structure of the cellulose fibers apparently formed a network, and poly (ethyl acrylate) was distributed uniformly among the fibrils. The rigid crystalline regions of the cellulose fibers apparently stabilized the amorphous, grafted poly (ethyl acrylate) to determine the mechanical properties of the elastomers (43, 44). For example, typical elastic recovery properties for these elastomers are shown in Table X. 

---