Titanate and zirconate coupling agents in foamed polymers

Ti or Zr coupling agents chemically bridge two dissimilar species such as a n inorganic filler/particulate and organic polymer via proton coordination without the need of water of condensation. They may also act as in situ cat alysts in the polymer melt at > 100 degreesC independent of filler content by one or mo re distinct organometallic mechanisms of conventional catalysi s, crosslinking, metallocene-like catalysis, repolymerization (US Patent 4, 657,988), and copolymerization. For example, minor amounts of titanate in u nfilled polymers will give 20% average faster polymer processing at 10% ave rage lower temperatures while increasing mechanical properties. As a result of titanate (zirconate) coupling and catalysis - gaseous, endothermic and exothermic blowing agents are made significantly more efficient to produce lighter polymers with more uniform cell structure because at the elevated t emperature where gas generation (blow) occurs polymer bubble stress (force/ area) properties are maintained or increased while strain (elongation/unit length) properties are increased to as much as double or triple thus reduci ng open cell formation. For example, cell size variation is reduced from 6- 48 micron to 9-15 micron in an exothermic azodicarbonamide-foamed PE. The d ensity of an azodicarbonamide-foamed flexible PVC is decreased threefold fr om 0.408g/cc to 0.129g/cc. The amount of endothermic sodium bicarbonate nee ded to foam SBR (Styrene Butadiene Rubber) is reduced twenty-nine fold from 15 phr of NaHCO3 powder to 0.68 phr of a 75% active NaHCO3 paste masterbat ch containing pyrophosphato titanate in the aromatic plasticizer phase.