Polypropylene is a thermoplastic, which is a man-made material that can be formed within a certain temperature range. The forming process for polypropylene and all other thermoplastics is reversible, meaning that the plastic can be reheated and reshaped. Basically, this process can be repeated indefinitely, as long as the plastic is not overheated, which would lead to its thermal decomposition. Thermoplastics like polypropylene can be used for many applications.
Today, they are the largest group of man-made materials. Polypropylene was developed in 1954 in Germany (Farbwerke Hoechst, Frankfurt am Main) and almost at the same time in Italy (Milan Polytechnic Institute). It was first patented in Italy, where industrial production began in 1957. Today, polypropylene is the second most important plastic (according to global sales), surpassed only by polyethylene (PE). In general, thermoplastics – including polypropylene – are easy to process. They can be welded, possess a high level of chemical resistance and good electrical insulation properties, which makes them a popular material in many industries. In addition, polypropylene has other characteristics desirable in a material used to make handle scales. It is very lightweight (polypropylene is the lightest of all plastics) and extremely hard at the same time. The material only rarely develops stress cracks. Moreover, the mechanical properties of polypropylene can be influenced and altered during production, which makes it even more versatile.
Thanks to its chemical and physical properties, polypropylene is a material with many applications and particularly well suited for injection molded parts. Film and foam products are also made from polypropylene. The lightweight, hard and relatively inexpensive material is widely used to make simple knife handle scales.