Polypropylene already is considered to be one of the most versatile polymers available, yet metallocene catalyst technology has led to a new type of PP. Fina Oil and Chemical Co. of Dallas developed and patented syndiotactic PP, a polymer that exhibits a greater degree of stability and more clarity than isotactic PP, its cousin.
Chemically, syndiotactic PP is the same as isotactic PP, but the polymers have different physical structures on the molecular level that alter their performance.
Metallocene catalysts make the production of syndiotactic PP possible, according to Joseph Schardl, manager of market development for plastics at Fina.
Without metallocene catalysts, more than 93 percent of the PP produced in a reactor is isotactic. The remainder is syndiotactic and atactic polymer, he said.
However, Fina produced and patented syndiotactic PP, and is conducting studies to determine the size of the markets to which it can be sold.
In a June 5 telephone interview from his office in Dallas, Schardl said Fina has done two commercial production runs of syndiotactic PP - in April 1993 and January. Those runs provided test quantities of the polymer. Fina hopes to have another production run before the end of this year, which indicates the level of interest in syndiotactic PP, he said.
``We have not done an exhaustive market survey to see where these polymers will fit,'' he said. ``However, we see this primarily as a niche product, and we're focusing our development efforts on narrow end-use areas.''
Fina is testing the polymer in applications for medical, film, adhesive and sports markets.
Syndiotactic PP can be compounded with additives used in isotactic PP, Schardl said, and the same quantities of additives can be used with syndiotactic as with isotactic PP.
Besides improved optical clarity and stability, he said, syndiotactic PP has demonstrated better impact strength at room temperature and a lower flexural modulus than isotactic PP, while processing similarly.
However, he acknowledged that syndiotactic PP costs four to five times more than isotactic PP. He expects Fina's decision on fully commercializing the polymer within two years.