| In this paper, a series of PPIPOEIBaSO4 ternary composites with different polypropylene matrix and different extent of polymer-filler interfacial interaction were designed and prepared. The effects of interfacial modification on the ciystallization behavior of PP matrix, the morphology, the mechanical properties and rheological behavior of PP/POEIBaSO4 ternary composites were studied. The toughening mechanisms were discussed by taking several factors into account, including the relationship between interfacial adhesion and micro-mechnisms of deformation arid fracture. The effects of interfacial design on the shear yield behavior and thixotropic behavior of ternary composites were discussed through rheological measurements.Three kinds of BaSO4 masterbatch with different surface modification of the filler were prepared, named for BM, BN and B0. BM masterbatch was prepared through grafting maleic andydride on the surfaces of BaSO4 particles and POE particles in one step, and BN masterbatch was prepared by blending BaSO4 treated through coupling agent of organic titanate with POE, while the BO masterbatch was prepared by directly blending BaSO4 with POE. All of these masterbatches were processed through twin screw extruder.For ternary composites containing BM masterbatch (EM, TM series), core-shell morphology is formed, BaSO4 inclusions encapsulated in shells of POE and dispersed in the PP matrix, interfacial interaction of the system is the strongest. For ternary composites containing BN or BO masterbatch, separated morphology is formed, in which BaSO4 particles and POE particles are separately dispersed into PP matrix. lnterfacial interaction in composites with BO masterbatch (EO, TO series) is stronger than composites with BN masterbatch (EN, TN series).-3--Due to the compatibility differences of POE with PP copolymer and PP homopolymer, the effects of POE on the crystallization behavior of the PP matrix are different. POE has heterogeneous nucleating effect on the crystallization of PP homopolyer, which speed up the rate of crystallization. However, the long octene molecule chains in POE inhibit the motion and rearrangement of PP molecule chains, resulting in the reduction of crystallinity of PP matrix.in ternary composites, BaSO4 particles also have heterogeneous nucleating effect on the crystallization of PP matrix, and their nucleating capability is influenced by the morphology and interfacial interactions. BaSO4 particles in composites with separated morphology have higher nucleating capability than those in composites with core-shell morphology. For ternary composites with separated morphology, the nucleating capability of BaSO4 particles is determined by the interfacial interaction between BaSO4 particles and PP matrix, the stronger of the interfacial interaction, the higher of the nucleating capability.Morphology and interfacial interaction play a very important role in the mechnical properties of ternary composites. The yield strength and impact tougheness of composites with core-shell morphology are higher than those of composites with separated morphology, but the former has lower flexural modulus and elongation at break than the latter.The results of lnstrumenta] Impact Test show that the toughening mechnisims of ternary composites have close relationship with the enhancement of crack propagation energy. Ternary composites with core-shell morphology have higher crack propagation energy, resulting in higher impact strength.SEM micrographs of the impact fractured surfaces of the composites indicate that at high rate of deformation, interfacial debonding between BaSO4 particles and PP matrix, and the shear-yielding of PP matrix induced by POE are the main toughening mechanisms in composites with separated morphology. For composites with core-shell morphology, core-shell inclusions cause the apparent volume of POE large; which in turn decreases the matrix ligament thickness, resulting in easier transition of localized stress state from plane-strain to pla...
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