Study On The Morphology And Toughening Mechanism Of Sandbag Toughened PA6/EPDM/nano-CaCO₃ Ternary Composite

In this paper,ethylene propylene diene terpolymer rubber?EPDM?/ maleated ethylene propylene diene terpolymer rubber?EPDM-MAH?,named as EPDM-M,and nano calcium carbonate?nano-CaCO₃?are employed to modify the toughness of Polyamide 6?PA6?.Nano-CaCO₃ agglomerate encapsulated by EPDM called "sandbag" which could effectively improve the toughness of PA6/EPDM/nano-CaCO₃ ternary composites was constructed.Relationship between phase structure and mechanical properties was studied by instrument charpy impact test and Scanning Electron Microscope?SEM?.The toughening mechanism of “sandbag” microstructure particles was further discussed.The main works and conclusions are listed as follows:1?The effect of the feeding rate and screw speed of twin screw extruder on the morphology of “sandbag” microstructure and the mechanical properties of PA6/EPDM-M/nano-CaCO₃ composites were studied.The result shows thatthe sand bag particles have better distribution in the matrix with the increasing feeding rate and screw speed.The tensile and flexural strength had little change with the increasing feeding rate and screw speed.The impact strength and crack propagation energy were increased with the increasing feeding rate,while rose firstly and then decreased with the increasing screw speed.The impact strength and crack propagation energy reached highest when the screw speed was 100 r/min.2?The effect of sandbag particle size on the charpy impact strength of PA6/EPDM/nano-CaCO₃ ternary composites was studied.The result shows that the sandbag particle size decreased with the increased of EPDM-g-MAH grafting degree and content.Meanwhile,the impact strength of the composites increased with the decrease of the sandbag particle size.The smallest particle size was 0.58?m and the impact strength of the composite reached 97.5kJ/m2.3 ? The effect of sandbag particle cavitation on the toughness of PA6/EPDM/nano-CaCO₃ ternary composites was investigated.The results showed that the elastic deformation and volume strain of EPDM-M/nano-CaCO₃ master batch were decreased when the content of dicumyl peroxide?DCP?increased from 0 to 0.4wt%,which lead to the decreased of the charpy impact strength of the PA6/EPDM/nano-CaCO₃ ternary composites.The cross linked EPDM would restrict the initiation and growth of cavities lead to poor toughness of the composite.That means the cavitation of sandbag particle made an important role in the sandbag toughened PA6 ternary composite.