A number of crystalline a-olefin polymers have now been reported using Ziegler3-Natta4 catalyst systems, and a comparison of their physical properties has been reported. In a series proceeding from polypropylene to polypentene-1, the melting point of the crystalline polymer decreases with increasing size of the side chain up to polyhexene-1 which is completely amorphous. However, a six-carbon and even a seven-carbon a-olefin can be ...