Graphene nanocomposites for improved golf ball performance and lifetime

The average golfer and most professionals play with two-piece, three-piece, or four-piece layered golf balls. A typical two-layered golf ball is composed of a crosslinked rubber core (polybutadiene or polyurethane) and a rigid and glassy outer skin (poly(methacrylic acid) ionomer. A crosslinked rubber is an ideal thermodynamic material that recovers completely after extensive impact (rubber elasticity). Polybutadiene rubber has a glass transition temperature of about -73 ̊C, which means that it remains rubbery at extremely low winter-like conditions. A crosslinked rubber maintains form when it is struck by dissipating the mechanical energy into heat energy. The temperature where damping is highest, for most amorphous polymers (rubbers), is the glass transition temperature. When a golf ball is struck, the hard and glassy skin receives the impact and transmits it to the rubbery core. The crosslinked rubber core absorbs and dissipates the impact energy making the golf ball highly resilient and durable. The ability to transfer the load from the skin to the core depends on their compatibility and the strength of the bond between them. The performance of the golf balls (distance traveled after striking) drops drastically under cold and wet conditions. It is reported that the hydrophilicity of the ionomers that make up the outer layer of the golf ball allows water to permeate and submerge into the rubber core, thereby causing disconnection of the two layers and disruption in load transfer from skin to core. It is imperative to develop a golf ball capable of maintaining highest performance in all weather conditions. In this proposed project, the hydrophilicity of the outer layer of golf ball will be reduced while maintaining high impact strength by reinforcement of poly(zinc-methacrylate acid (PZnMAA)) with surface modified graphene nanosheets. Preliminary results obtained in our laboratory show that reinforcement of hybrid polymer matrix with graphene nanosheet exhibited a simultaneous increase in the storage modulus and damping ability [1,2]. It was also shown that the rubbery plateau of glassy polymers is increased by about three orders of magnitude [2]. We propose to extend this discovery to golf ball technology by reinforcing both the skin and core of a golf ball with surface modified graphene nanosheets. We expect that reinforcement of both the crosslinked rubber and PZnMAA with graphene will lead to simultaneous increase in storage modulus and impact resistance while maintaining highest damping ability over a wide range of temperature, frequencies, and time scale. Furthermore, uniform dispersion of graphene in PZnMAA matrix and polyurethane matrix will be achieved by in-situ polymerization in the presence of the filler. Dispersion will be monitored using Raman Spectroscopy by comparing the ratio of carbon D-peak to graphite Gpeak for the powder graphene nanosheets with the modified filler. Additional information about dispersion and exfoliation of graphene will be obtained from Transmission Electron Microscopy, as well as Wide Angle X-Ray Spectroscopy. The thermomechanical properties and damping behavior of the graphene nanocomposite will be determined by using Dynamic Mechanical Spectroscopy and correlated with impact strength. The high aspect ratio nanographene sheet modified with hydrophobic polyaniline will prevent wetting of PZnMAA and water permeation and toughen the system crack bridging while maintaining high storage modulus. The broader impact of the proposed research is the integration of nanotechnology in golf ball construction in order to improve their performance and lifetime.