Effects of core‐shell structured rubber on biobased polyamide 56 with stiffness and toughness balance

Abstract There is great social awareness concerning the use of biobased materials of diminishing the rapid resource depletion and suppressing global warming. The inherent drawbacks of biobased polyamide 56 (PA56) such as poor notched impact strength limit its applications. Core‐shell structured impact modifiers consisting of a soft glycidyl methacrylate grafted poly(ethylene–octene) (POE‐g‐GMA) shell and a rigid polypropylene core were synthesized through the differences in interfacial tensions. Core‐shell rubber (CSR) particles were used to toughen biobased PA56 by melt blending. PA56/CSR composites exhibited a 560% increase in the impact strength, while the tensile performance loss was slight. This desirable toughness of biobased PA56 is attributed to the cavitation that occurred in POE‐g‐GMA shell which can induce shear bands and shear yielding, forming the fibrils. Characterizations, including X‐ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), melt rheological tests, and dynamic mechanical analysis (DMA) were conducted to study the toughening mechanism. The results indicated the massive shearing yielding, the cavitation of the CSR and interfacial debonding between the POE‐g‐GMA and the PP were the principal toughening mechanisms.