How does grafting modify the properties of natural rubber?

Grafting modifies the properties of natural rubber by chemically attaching different polymer chains (grafts) onto the natural rubber backbone. This process creates a copolymer with a combination of the properties of both the natural rubber and the grafted polymer. The specific effects of grafting depend on the type and amount of the grafted monomer. Grafting can improve oil resistance by grafting polar monomers, such as acrylonitrile or methyl methacrylate, onto the non-polar rubber backbone. This increases the overall polarity of the rubber, making it less susceptible to swelling in oils. Grafting can enhance the thermal stability of natural rubber by introducing thermally stable polymers as grafts. This protects the rubber from degradation at elevated temperatures. Grafting can increase the tensile strength and tear resistance of natural rubber by using monomers that form strong, rigid polymer chains. Grafting can also improve the adhesion of natural rubber to other materials by selecting grafts with functional groups that promote bonding. Grafting can modify the surface properties of natural rubber, such as its hydrophobicity or hydrophilicity, by using grafts with the desired surface characteristics. For example, grafting methyl methacrylate onto natural rubber improves its compatibility with plastics, while grafting acrylic acid improves its water absorption.