Reinforcement of Polyamide 6 and Its Montmorillonite Composites by Introducing Maleinized Low-Molecular-Mass Polybutadiene Rubber

The effect of adding maleinized low-molecular-mass polybutadiene rubber on the structure and mechanical properties of polyamide 6 and its composites with the initial and organophilized montmorillonite was studied. The composites were prepared by compounding in a melt in a two-worm extruder. Specimens for the studies were prepared by pressure casting. The structure and properties of the composites were studied by differential scanning calorimetry, X-ray diffraction analysis, dynamic mechanical analysis, and mechanical tests. Modification of the polyamide by adding maleinized rubber increases the strength, the tensile and bending elastic moduli, the extension stress, and the relative elongation at break. Structural changes are manifested in a decrease in the melt flow index by 2 orders of magnitude and in the mechanical loss tangent at temperatures exceeding the glass transition point. These changes suggest an increase in the molecular mass of the polymer. When montmorillonite and maleinized rubber are added jointly, the character of changes in the rheological and strength characteristics of the nanocomposites is similar to that observed in modification of unfilled polyamide 6. According to the data of X-ray diffraction analysis and scanning electron microscopy, in processing of melts of the modified composites the degrees of the clay exfoliation and of the clay particle orientation increase. This ensures an additional increase in the bending elastic modulus and bending strength compared to the corresponding tensile characteristics due to predominantly normal orientation of clay particles relative to the bending stress.