Name and synonyms for polypropylene: 
IUPAC-Name (International Union of Pure and Applied Chemistry):
poly(1-methylethylene)
Synonyms:
polypropene, 1-propene
German:
Polypropylen
Spanish:
polipropileno
French:
polypropylène
Italian:
polipropilene
Russian:
Полипропилен
Arabic:
بولي بروبيلين
Chinese:
聚丙烯
Japanese:
ポリプロピレン
Chemical formula:
(C3H6)n
CAS-Nr.:
9003-07-0
ESIS entry:
-- (no EINECS or ELINCS Registration)
Polypropylene is a semi-crystalline thermoplastic polymer, which belongs to the polyolefin group and is manufactured through the polymerization of the monomer, propene, with the help of catalysts. PP has been produced since 1957, and today it is the plastic with the second-largest demand. Its production volume is surpassed only by polyethylene. Approximately 45 million tons of PP were sold in the year 2007.
PP is tough and exceptionally resistant to many chemical solvents, acids, and bases. This versatile material is utilized in a multitude of applications in practically all plastic markets. Designers and manufacturers are able to choose from more than 3,000 different commercial grades of PP, whereby isotactic PP outweighs the rest. The expensive syndiotactic PP is exceedingly transparent and very impact resistant, but not particularly rigid. Atactic PP is basically only applied to asphalt coatings.
Polypropylene is produced commercially in various forms, depending upon the desired characteristics. In addition to PP homopolymers, there is a wide range of copolymers and terpolymers, in two forms: random and block copolymers. These basic forms overlap each other to a certain degree, but they have certain general characteristics which help to choose the best material for specific applications.
Information on manufacturing and processing methods, as well as consumption shares for the different PP grades can be found in Market Study - Polypropylene, from Ceresana Research.
Important characteristics of polypropylene:
|
Parameter: |
PP: |
|
Density (g/cm³) |
between 0.895 and 0.92 |
|
Melting point (°C) |
between 160 and 170 |
|
Service temperature (°C) |
100 (maximum continuous use temperature) |
|
Tensile strength (N/mm²) |
between 21 and 37 |
|
Tensile strength at break (N/mm²) |
~ 37 |
|
Chemical resistance |
Resistant to weak acids and bases, alcohols, organic solvents and fats; not resistant to gasoline, benzene and hydrocarbons; easily soluble in xylene, tetralin and decalin |
Molecular structure, molecular weight, molecular mass distribution, and other parameters of PP can be modified, for example through changes in the regularity and length of the chains, or through incorporation of a comonomer. Consequently, the many PP varieties have various characteristics. In general, PP is the most light-weight plastic, as a result of its low density. PP has the highest melting point of all thermoplastics, and in comparison to polyethylene, it is more resistant to high temperatures, more rigid, and tougher. In addition, PP has good resistance to wear, chemicals, and detergents, good transparency, and good process-ability with injection molding and extruding. One of PP's primary advantages is its resistance to environmental stress cracking. Environmental laws and food regulations also speak in favor of PP.
An overview of PP's most important characteristics, as well as detailed information on additives and fillers used in this plastic are provided in Market Study - Polypropylene, from Ceresana Research.
Hazard indications polypropylene:
No mandatory danger symbols (R/S statements) are required to label polypropylene. The plastic is considered to be safe and non-toxic, and is used in numerous applications that come into contact with foods, drinking water, and medications. Health concerns and provisions for PP only relate to the use of pigments and other additives which can migrate from the material. Polypropylene is one of the most easily recyclable polymers.
Additional information on environmental discussions on plastics, legal issues, work safety, and various recycling methods can be found in Market Study - Polypropylene, from Ceresana Research.
Manufacturing methods for polypropylene:
PP is manufactured through the polymerization of propylene, either alone or with small portions of other monomers and the help of a catalyst (generally titanium-based). A second co-catalyst (triethyl aluminum) is added, in order to initiate the polymerization reaction. Hydrogen is inserted into the reactor for the purpose of controlling the polymer's molecular weight. This reaction is produced with help from one of three methods: suspension process (slurry method), bulk process, or gas phase polymerization.
It is possible to change the material's characteristics and customize a large variety of customized polypropylene grades through controlling the monomers, catalysts, and process conditions. Possibilities are expanded even further through PP's ability to absorb fillers and reinforcers better than polyethylene, for example.
Detailed information on PP processing and production, which employs Ziegler-Natta or metallocene catalysts, is provided in Market Study - Polypropylene, from Ceresana Research.
Application examples for polypropylene:
PP is one of the most ubiquitous plastics ever developed; its well-balanced characteristics, which can adapt to a multitude of manufacturing processes and applications, and its relatively low price, make the use of PP sensible in the most diverse range of industries.
The automotive industry is the largest consumer of PP, worldwide. Mineral and glass reinforced PP, PP homopolymers and copolymers, as well as thermoplastic vulcanisates and PP foams are used in every segment of the automotive industry. Examples include anything from individual components and energy absorbing parts, to interior trim, carpet lining, and fluid containers.
The injection molding process is the most frequently used PP processing method. It is used to manufacture household goods like food containers, toys, suitcases, bicycle helmets, child seats, and folding chairs. Polypropylene is the favored material for creating many complicated molded parts, such as internal dishwasher components. Fiberglass and Talc reinforced PP homopolymers are typically used for washing machine parts. Low weight, rigidity, simple mold-ability, color quality, and excellent insulating characteristics are all advantages of PP, favorable in small electrical devices.
Since polypropylene is generally non-toxic, chemically inactive, and able to be sterilized, it is able to be used for products in the medical field. The primary application here is disposable syringes, which are typically manufactured from PP homopolymers and sometimes from random copolymers. Other examples include containers for medications, Petri dishes, catheters, diagnostic equipment, and secure containers for contaminated medical instruments.
The use of polypropylene continues to increase in textiles; PP fibers, for example, are the most commonly used plastic fibers in carpet. Non-woven fabrics form the largest application area for PP fibers: surgical clothing, disposable diapers, sanitary towels, and other hygiene products. Rope made from polypropylene is of particular importance: PP rope is lighter than water and has a force to weight ratio ten times greater than steel. Accordingly, nearly all ships are equipped with ropes and nets made from PP.
Polypropylene also plays a large role in the packaging sector, whereby it is only surpassed by polyethylene. PP is the preferred product for bottle caps, due to its rigidity and resistance to crack formation even upon significant impact. Prepared foods that do not require freezing and can be heated in the microwave are offered in sealed PP containers. Scotch® tape is another everyday product made from PP.
Market Study - Polypropylene from Ceresana Research offers comprehensive information on consumption amounts within individual application areas and divides them among the different world regions.
(->for more info see Market Study - Polypropylene from Ceresana Research)
Last revision: 19.01.09
