Dependence of the fracture and fatigue performance of polyolefins and related blends and composites on microstructural and molecular characteristics

This article surveys the influence of microstructural, morphological and molecular variables on the fracture and fatigue behavior of polyolefins, related blends and composites. The effects of major parameters of the structural hierarchy on the fracture mechanics (FM) response were considered and the related model descriptions reviewed. Emphasis was put on how important is to select the right FM approach for the toughness determination. It was pointed out that a clear distinction between crack initiation and growth is the essential prerequisite to differentiate between effects of the initial structure and its alteration due to mechanical loading. Although the microstructural dependence of the fracture and fatigue properties in reinforced, filled and impact modified polyolefins is quite well explored, this information is still missing for the neat polymers. This is due to a strong interlinking among molecular and morphological variables in neat polyolefins. Recommendations were given how to overcome this difficulty.