Overcoming Incompatibility Problems in Elastomer Blends

Rubbers are challenging composite materials, whose functionality strongly depends on the morphology of the materials. Distribution and dispersion of fillers and curing agents in polymer blends are critical, as these components differ significantly in polarity and surface energy. A coating changing the surface properties of additives while maintaining the chemical and structural functionalities is expected to enhance the compatibility within elastomer blends, and improve the properties.
Plasma polymerization allows functionalization of the surface of particular materials. Using this technology, the surface polarity can be tailored to better match the polarity of the matrix, and chemical moieties can be introduced to better interact with the polymer.  
Within this study, silica and curing agents were coated with different plasma-polymers, and the modified additives were tested in polymers differing in polarity and degree of unsaturation, and in their blends. A better polarity match between additives and polymers results in improved material properties: Changes in surface polarity significantly influence filler-filler and filler-polymer interaction and can improve compatibility of the polymers in a blend. This finally leads to significantly improved mechanical properties of the material due to a more homogenous distribution of the additives within a polymer blend and stronger filler-polymer interactions.