Onset critical strains as an effective parameter for compatibilizer efficiency in a polypropylene‐poly(ethylene terephthalate) blend

The effectiveness of a compatibilizer is responsible for improved mechanical properties of immiscible blends. The enhanced interactions between the phases are assessed via critical plastic strain (onset of fine slip caused by local intra-/interlamellar slip) and critical elastic strain (onset of fibrillation of crystalline skeleton). PP-PET blends were compatibilized with three maleic anhydride grafted compatibilizers with different backbones: PP, SEBS and POE. Using this critical onset strain method, via free shrinkage experiments, allowed to identify the effect of PET on the matrix’s deformation and also the different contributions of the compatibilizers to the deformation mechanisms. Results showed that PPgMAH promoted best PET’s plastic deformation to the matrix, relative to the other compatibilizers. However, SEBSgMAH’s elastomeric backbone provide better stress dissipation before onset of fibrillation compared to the binary blend and matrix. This method can be used as a way to assess the effectiveness of a compatibilizer in an immiscible blend