Abstract: A process for preparing thermoplastic rubbers from blends of vulcanized rubber scrap materials and virgin Natural Rubbers is provided comprising blending the vulcanized rubber scrap materials with virgin Natural Rubbers (NR) on a two roll mill or an internal mixer to form a polymeric mixture, followed by passing the polymeric mixture with an olefinic plastic through a twin screw extruder along with devulcanizing additives at elevated temperatures. The plastic resin may be a virgin resin, a recycled resin or a mixture thereof. The process is termed “dynamic devulcanization” to denote that the rubber scrap material is being devulcanized and intimately homogenized with virgin NR while it is being blended with the plastic resin to form the said thermoplastic natural rubber. A compatibilizing agent such as phthalic anhydride is introduced at the tail end of the twin-screw extruder to enhance the interface adhesion between the devulcanized rubber, virgin NR and the plastic resin.

Abstract: This invention relates to a storage stabilized recycled and devulcanized tire rubber modified asphalt composition, which comprises: 65.0 to 90.0% by weight of a neat asphalt, 3.0-50.0% by weight of a recycled and devulcanized rubber from used tires and/or other scrap rubbers, 0.01-15.0% by weight of a compatibilizer/stabilizer derived from Natural or Synthetic Rubbers, which composition passes the “cigar tube” softening point test difference of less than 5° C. between the top and bottom layers; and, the process for the said asphalt composition comprises mixing 65.0% to 90.0% by weight of a neat asphalt, 3.0 to 50.0% by weight of a recycled and devulcanized rubber from used tires, 0.01-10.0% by weight of a compatibilizer/stabilizer derived from Natural or Synthetic Rubbers, using high shear mixers at elevated temperatures of between 120° C. and 175° C. for between 15 minutes to 6 hours, to obtain storage stabilized asphalt composition that is stable in hot storage and transportation conditions.

Abstract: A process for the manufacture of rubber process aids from blends of vulcanized rubber powders, virgin polymers and thermoplastic resins. The process is carried out in a single stage using an extruder. The extruder is fed in three sections with feed hoppers. Vulcanized rubber powder of selected origin is fed into the hopper in the first section with part of the thermoplastic resin and oxidizing agents. The balance of the thermoplastic resin is fed in the second section. Virgin polymer is fed into the hopper in the third section. The temperature of the extruder is controlled and dwell time of the material passing through each of the extruder's sections is adjusted to ensure adequate mixing of all the polymers whereby a reactive rubber process aid in free flowing particulates is produced that acts as an excellent process aid in rubber processing.

Abstract: A process for preparing thermoplastic rubbers from vulcanized rubber scrap material is provided comprising devulcanizing the vulcanized rubber scrap material while blending the vulcanized rubber scrap material with an olefinic plastic resin in the presence of devulcanizing additives. Preferably, the vulcanized rubber scrap material is first milled prior to blending with the olefinic plastic rein. The plastic resin may be a virgin resin, a recycled resin or a mixture thereof. The process is termed “dynamic de-vulcanization” to denote that the rubber scrap material is being devulcanized while it is being blended with the plastic resin to form the thermoplastic rubber. The resultant thermoplastic rubbers exhibit superior physical properties such as tensile strength, elongation, hardness and flexural modulus compared to thermoplastic rubber compositions comprising mixtures of plastics and recycled rubbers heretofore produced.