Orientation characterization in polypropylene

Abstract

Orientation of polymers enhances many of their properties, particularly mechanical, impact, barrier and optical properties. Orientation processes can generally be classified into three categories: fibers, films and parts (sheets, bottles, rods, etc.). Polypropylene (PP) is widely used for all three applications. In the case of fibers, the fiber spinning process and fiber/textile applications of PP have a share of about 25% of total production [1]. Films, on the other hand, constitute a major application for PP (about 35% share of the total production) [1] and it is the one that involves biaxial orientation. Biaxial orientation has the added advantage of allowing property enhancement in two directions (i.e. avoiding any weakness in the transverse direction). The most widely used biaxial orientation processes for films are tubular film blowing and cast film biaxial orientation (or tentering). Finally, other processes, such as blow molding, compression and injection molding, and thermoforming produce oriented articles of PP for diverse applications. The applications that take most advantage of these oriented forms of PP are the textile and packaging industries.