Effect of metallic salts of malonic acid on the formation of β crystalline form in isotactic polypropylene

The effects of malonic acid and the lithium, sodium, potassium, zinc, magnesium, calcium, strontium, and barium salts of malonic acid on the formation of crystalline form in isotactic polypropylene at the crystallization temperatures 120 and 130 degrees C have been investigated. It was found that malonic acid and the lithium, sodium, and potassium salts of malonic acid inhibit the formation of beta crystalline form in polypropylene. Zinc malonate has a limited positive effect on the formation of beta crystalline form, while magnesium, calcium, strontium, and barium salts are beta nucleating agents, in descending order. The decreased beta nucleation abilities of the alkaline earth metallic salts of malonic acid are attributed to the increasing atomic radii of the combined metals and decreasing crystallization temperatures.