Ionically bonded filler-elastomer composites

Tertiary amine‐modified corn starches were converted to their basic or hydroxide form and combined with carboxylated butadiene–acrylonitrile copolymer and butadiene–styrene–sulfonic acid polymer to produce ionically bonded filler–elastomer composites. An increasing percentage of the elastomer fraction in the starch–elastomer composite is insolubilized as the starch‐to‐elastomer ratio increases. In addition to ionic bonding, a significant amount of elastomer is believed to be physically adsorbed onto the filler. The resulting composites are reprocessible, and some have sufficient tensile properties at room temperature for making rubber goods.