Fracture in Polymer Melts: History and State-of-the-art

In polymer melts, pre-existing micro-cracks and imperfections are not responsible for the crack initiation like in solids as surface tension minimizes the possibility of such defects. A limited explanation on mechanics behind the fracture of polymer melts is available in the literature despite its critically for the process design and exploiting the best properties of the polymers. A comprehensive discussion on experimental data and proposed theories addressing melt fracture are presented. The historical development and comparison of the literature along with the possible future direction related to polymer melt fracture are summarized. The modelling approaches that could relate the polymer structure with extrudate distortion and flow characteristics along with few original finite element modelling results are presented. The literature demonstrates that multiple cracks are originated and propagated simultaneously in the polymer melts but the position of initiation of crack is random but possibly depends on the rapture of primary C-C bonds. The C-C bonds break when strain energy equalizes energy of the covalent bond. In addition to this, the criterions of polymer melt fracture available in the literature are briefly discussed. This review should provide a quick understanding of this research area.