Polypropylene

Polypropylene (PP) is a thermoplastic polymer from the polyolefin group, which belongs to the most common plastics, used in many sectors of the food and textile industries and in laboratory equipment. It is sold under trade names such as Tipplen, Tatren, Mosten, etc.

Polypropylene has similar physical and chemical properties to polyethylene. It becomes brittle at low temperatures, softens around 140-150 degrees Celsius, and melts around 160-170 degrees Celsius. It is resistant to oils, organic solvents, and alcohols, and dissolves well in xylenes or tetrahydronaphthalene. Polypropylene stands out for its excellent chemical and mechanical resistance.

Polypropylene is often used for the production of ropes and cords due to its low density - the ropes are then light enough to float on the surface. Polypropylene is also used as an alternative to polyvinyl chloride (PVC) for insulating electrical cables in poorly ventilated environments, especially in tunnels. Polypropylene does not produce as much smoke and no toxic halogenated hydrocarbons during burning, which could contribute to the formation of various acids at high temperatures. It has an assigned international identification number for plastics. In 2001, the annual global production of polypropylene exceeded 30 million tons.

About 20% of polypropylene is produced as textile fiber, with industrial production beginning in the late 1950s in Italy. In the 2nd decade of the 21st century, the annual production of PP fibers reached approximately 6 million tons, with about 60% being filaments and 40% staples. The raw material for production is waste generated during oil processing, making polypropylene cheaper than other synthetic materials. The polymerized mass is melted and stretched at a temperature up to 200 °C. During this process, dyes are often added, as the finished fiber is very difficult to dye.

Polypropylene is the lightest of all textile fibers (0.91 g/cm³), the fiber is resistant to chemicals, has very good abrasion resistance, minimal moisture absorption, low tendency to static electricity, and pilling. In touch, PP fibers do not differ from sheep wool. Disadvantages include low recovery ability after deformation, low resistance to the effects of light and higher temperatures.