Micro-mechanical modelling of Young’s modulus of semi-crystalline polyamide 6 (PA 6) and elastomer particle-modified-PA 6

In this study semi-crystalline polyamide 6 (PA 6) and its composites consisting of a semi-crystalline PA 6 matrix filled with up to 32.9 vol.% submicron elastomeric copolymer particles are investigated. The aim of this paper is to show how micro-mechanical modelling can predict the elastic behaviour of these composites from the experimentally observed morphology and determined parameters.Semi-crystalline PA 6 possesses a spherulitic morphology, consisting of a radial assembly of amorphous layers and nano-sized crystalline lamellae. In the continuum mechanical representation of semi-crystalline PA 6, nano-sized crystallite lamellae are considered as a phase which is additionally embedded into the amorphous matrix. The 2D self-consistent embedded cell model was chosen to predict the Young’s modulus of the semi-crystalline PA 6 material. In this model a rectangular lamella is surrounded by an amorphous matrix, which is again embedded in the semi-crystalline PA 6 material with the mechanical behaviour to be determined iteratively in a self-consistent manner. The Young’s modulus of PA 6 has been calculated by an appropriate integration of results of all orientations of the crystalline lamellae. The Young’s modulus of PA 6/elastomer composite is also predicted by a 3D self-consistent embedded cell model. In this model a circular inclusion is surrounded by the PA 6 polymer matrix, which is again embedded in the PA 6/elastomer composite. Good agreement is obtained between experiments and the prediction with the self-consistent embedded cell models.