| The polymer composites filled with inorganic nanoparticles are more and more popularfor its superior overall performance. Compability between the inorganic particles and thepolymer matrix affects the dispersion of the inorganic particle, furthermore the dispersion ofparticles is the key factor which determines the impact properties of material, and the above isthe current study point. At the same time, how to describe the roughness and hierarchycomplexity of impact fracture surface quantitatively, rather than to judge the impact propertiesof material qualitatively by observing the cross-sectional morphology becomes the majorproblem which bothers the material experts a lot. If the impact fracture surface could succeedin quantitative characterization, it will have a positive significance in promoting for theresearch on the mechanical properties of polymer composites.In this paper, the organic quaternary ammonium salts of three different structures wereused to modify the sodium montmorillonite(MMT), then the nylon6/organic MMTcomposites were prepared by melt blending method and in site polymerization method, totoughen nylon6by the special layered structure of MMT. XRD tests showed that the PA6molecular chain had intercalated into the layers of organic MMT, to form the intercalatednanocomposites. The impact property of PA6composites with three different organic MMTwas studied by the V-notch impact experiments, and it was found that the impact strength ofPA6/MMT composites could reach to a maximum of7.0kJ/m2, which increased by22.4%than that of neat PA6. According to the cross-section SEM images, the fracture surface of neatPA6owned the characteristic of smooth and fewer bumps, belonging to brittle fracture; on thecontrary, the fracture surface of E and P series samples showed different roughness andhierarchy complexity, belonging to toughness fracture.The fractal theory was used for further research on the impact fracture surfacemorphology of PA6/MMT composites, the profile curve and three-dimensional morphologyof fracture surface could be quantitatively characterized by profile curve fractal dimension DLand surface dimension Ds respectively. The results showed that data linear correlationcoefficient were all above0.9, the strong correlation proved the obvious fractal behavior ofimpact fracture surface profile curve and surface morphology; whether melt blending method or the in situ polymerization method, the fractal dimension of fracture surface profile curveshowed the following trend: DL1>DL2>DL3>DL0, as well the surface fractal dimension Dsexhibited the same magnitude relationship; Ds value and impact strength of PA6/MMTcomposites possessed positively correlated proportional relationship. |
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