Abstract
Ground tyre rubber (GTR) powder has been treated using a novel surface grafting process allowing the incorporation of various chemical functional groups onto the polymer surface. The GTR was functionalised with methacrylic acid by photoinitiated polymerisation. The process comprises two steps: UV irradiation of GTR in the presence of air, followed by grafting of methacrylic acid (MA) onto the GTR surface. The presence of reactive carboxy groups, which was confirmed by titration, provides the possibility of covalent linkage with reactive groups when the powder is blended with a suitable matrix polymer.
The effectiveness of the process was assessed by examining the tensile and Charpy impact properties of polyamide and epoxy compounds containing ungrafted and grafted GTR. A significant improvement in the tensile properties of polyamide was observed on adding methacrylic acid grafted GTR. The grafted GTR also worked as an impact modifier in epoxy compounds. The best results to date were achieved when methacrylic acid grafted GTR was added to polyurethane formulations.
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