An addition polymer made from the monomer propylene, it is rugged and unusually resistant to many chemical solvents, bases and acids. Polypropylene has a relatively slippery “low energy surface” that means that many common glues will not pp woven bags manufacturing process pdf adequate joints. Joining of polypropylene is often done using welding processes.
In 2013, the global market for polypropylene was about 55 million tonnes. Polypropylene is the world’s second-most widely produced synthetic plastic, after polyethylene. Paul Hogan and Robert Banks first polymerized propylene in 1951. Propylene was first polymerized to a crystalline isotactic polymer by Giulio Natta as well as by the German chemist Karl Rehn in March 1954.
This pioneering discovery led to large-scale commercial production of isotactic polypropylene by the Italian firm Montecatini from 1957 onwards. Syndiotactic polypropylene was also first synthesized by Natta and his coworkers. The sales of this material are forecast to grow at a rate of 5. Polypropylene is in many aspects similar to polyethylene, especially in solution behaviour and electrical properties.
The additionally present methyl group improves mechanical properties and thermal resistance, while the chemical resistance decreases. In isotactic polypropylene, for example, the CH3 groups are oriented on one side of the carbon backbone. This creates a greater degree of crystallinity and results in a stiffer material that is more resistant to creep than both atactic polypropylene and polyethylene.
The density of PP is between 0. Therefore, PP is the commodity plastic with the lowest density.