Polypropylene ionomers

The preparation and properties of highly crystalline ionomers formed by the copolymerization of propylene and low levels of ethylcholoroaluminium 10‐undecenoate have been investigated. Few of the variables studied had dramatic effects on the copolymerization. Thus, a five‐fold increase in undecenoate concentration gave only about a 20% increase in acid incorporation into the copolymer. Increasing temperature resulted in increased acid content, but handling problems in a I gal stirred reactor limited polymerization of 80°C. Rates were lowered in the presence of complex, but the effect was minimized by hydrogen. Rheological measurements showed an increase in low shear melt viscosity of the pottasium salts by up two orders of magnitude relative to the acid from. Ionomers containing two or more carboxyl groups as their potassium salts, and having a broad molecular weight distribution, had an extended rubbery plateau range, covering most of the shear ranges of normal processing. The zero‐shear activation energy for viscous flow was 42 kcal, comparable to ABS and polystyrene. These ionomers are promising candidates for thermoforming applications