Chain Scission and Disentanglement

For these reasons, PMMA and its maleimide and glutarimide copolymers represent very suitable materials for investigating the effect of the chemical structure and of the solid state molecular motions on the plastic deformation, the occurrence of the various micro-mechanisms of deformation (chain scission crazes, shear deformation zones, chain disentanglement crazes), as well as the fracture behaviour. 

In order to understand fracture behaviour, it is important to analyse the types of deformation micromechanisms undergone under strain chain scission craze (CSC), shear deformation zone (SDZ), chain disentanglement craze (CDC) and the temperature range over which each one occurs. Furthermore, it is worth wondering whether these micromechanisms are related to /i transition motions. 

The toughness Gc (Eq. 20) is related to material features such as the surface density of entangled chains in the fibrils vs and the force for chain scission /b. The value of vs depends on the amount of disentanglement induced by the fibrillation together with the initial entanglement density of the bulk. 

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