Titanates and Zirconates–Different Than Silanes and Why That Matters to Rubber Compounders

Organometallic Ti or Zr coupling agents provide alternative coupling agents to silanes and work to adhere to substrates where silanes don’t – such as E-glass reinforced ETFE, carbonaceous surfaces, metal carbonates and sulfates; aramids; crumb rubber and organics. The differences will be explained through their chemistry and Six Functions. Unlike silanes, titanates Function 1 “couple” or “react” with CaCO3 that have no apparent hydroxyl groups.

Titanates are shown to be Function 2 catalytic with so-called “inert” systems such as CaCO3 filled thermoplastic elastomers and will be shown to impart metallocene-like flexibility and flow characteristics to reinforced, filled and UNFILLED polymers independent of any curative or x-link mechanism. Titanates will be shown to be used in-situ on macromolecules to act as Repolymerization and Copolymerization catalysts that filler couple and reduce polymer viscosity while increasing stress-strain strength. 

Whereas silanes require HYDROXYL (OH)  groups, limiting surface reactivity with Calcium and Carbon, subject organometallics, depending on their chemical structure, PROTON (H)+ coordinate or react via solvolysis with surface hydrogens on organics and inorganics. Carbon, Aramid, PP, PET, Steel Fibers; CaCO3; CaSO4; BaSO4; Cement; Oil-Soaked Interfaces; ATH; Mg(OH)2; Carbon Black, Graphene; CNT’s; Pigments; Metal Powders; Metal Oxides; Nano-clays; Nano-particulate; Rubber Crumb, Polymers, etc. once atomic monolayered become catalytic and heteroatom organometallic functional to enhance, for example: bonding; flame retardance; conductance; impact strength; long-term aging against salt; chemical and thermal attack; repolymerization or copolymerization catalysis, which induces metallocene-like “flexibilization” without – or with less – plasticizer, diluent, or water in filled and unfilled thermoplastics and thermosets, as well as compatibilization and co-catalysis with other polymers. For example, the flexibilizing and denerving effect on unfilled ethylene-propylene EPR rubber is achieved with 0.2 phr additive.

This increase in strain (elongation/unit length) behavior of the uncured polymer backbone while not diminishing stress strength (Tensile = F/A) applies to thermosets such as elastomers, unsaturated polyester, vinyl ester, polyurethanes, epoxies, acrylics, etc., which will be shown to lead to increased impact strength and toughness.  The paper will show how titanate catalyzed elastomers and polymer can be foamed more effectively with endothermic and exothermic blowing agents.

The paper will discuss the importance of understanding the interface between two dissimilar materials such as a filler and polymer and why certain practices such as ammonium quat exfoliation of nano-clays during their manufacture interferes with their subsequent utility in non-Nitrogen bearing olefinic polymers.

Titanates and Zirconates will be shown via discussion of recent ACS CAS Search Abstracts of work by other investigators to be a dynamic arena for dramatic changes, often causing a new paradigm in thermoplastic and thermoset polymer technology. The paper will review some of the more interesting developments in the field of alternate interface technologies.