THE USE OF CRYOGENICALLY GROUND RUBBER TIRES AS A FILLER IN POLYOLEFIN BLENDS

The effects of cryogenically ground rubber tires (CGT) on some of the mechanical properties of blends with linear low density polyethylene (LLDPE) and high density polyethylene (HDPE) are presented. Precoating the CGT particles with an ethylene-acrylic acid copolymer is shown to overcome most of the deleterious effects of adding CGT to LLDPE, while still retaining composite processability. A blend of 40 wt% EAA coated CGT particles with LLDPE is shown to have impact and tensile strengths that are 90% of those for the pure LLDPE, representing increases of 60 and 20%, respectively, over blends with uncoated particles. Blends of LLDPE with ground tire bladders demonstrate that even better mechanical properties can be obtained with similar large rubber particle size but somewhat better adhesion. For HDPE, however, it is shown that with large rubber particles, moderate adhesion is not sufficient to produce useful composites.