The effect of devulcanization level on mechanical properties of reclaimed rubber by thermal-mechanical shearing devulcanization

Ground tire rubber (GTR) with crosslinked structure has hardly any plasticity and processability, which makes its property very poor. Thermal-mechanical shearing devulcanization method can effectively destroy the crosslinked structure and restore GTR a certain extent of plasticity and processability. This article investigated the characteristic and reprocessing performance of reclaimed rubber prepared through thermal-mechanical shearing devulcanization. The relationship between the devulcanization level (indicated by gel fraction and crosslink density) and the mechanical property was analyzed by sufficient experiments. Fourier transform infrared spectroscopy and elemental analyzer studies revealed the chemical structure of GTR changed and many complex reactions occurred after devulcanization. The gel permeation chromatography indicated the specific changes of molecular weight and molecular weight distribution in devulcanization process. The differential scanning calorimetry revealed various vulcanized abilities and vulcanized structures of reclaimed rubber. The scanning electron microscope further confirmed the recovery of plasticity after devulcanization and the distinct vulcanized structures between revulcanizates. The determination of devulcanization level and mechanical properties verified that mechanical properties especially tensile strength reached to the optimum value only at an appropriate devulcanization level. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013