Polypropylene's (PP) intrinsic properties of high stiffness, good tensile strength and inertness toward acids, alkalis and solvents has secured its position in a wide range of consumer and industrial products. In addition, PP's low density and traditional cost advantage over other thermoplastic polymers make it suitable for applications that are weight and cost conscious.
Injection moulding is the largest PP market but it can also be made into fibres, film and sheet and extruded into pipe and conduit. Polypropylene and its alloys have become the plastic of choice in the automobile industry.
Polypropylene has been one of the fastest growing commodity resins. Growth has been slowing but it is still expected to continue at nearly 6%/year. However, global capacity is being expanded at even a faster rate with overcapacity likely to become a problem from 2011. The concentration of capacity growth in the Middle East and Asia Pacific will also change trade patterns.
Polypropylene was first produced in a slurry process using Ziegler-Natta catalysts. Bulk phase technologies were then developed while higher activity catalysts enabled gas phase processes to be used. A combination of bulk phase tubular and gas phase reactors has become a popular process
Polypropylene is a colourless, translucent to transparent solid with a glossy surface. Polypropylene does not present any risk to the skin. The polymer should not be exposed to flames as it gives off smoke on burning.