Polypropylene fiber, also known as polypropene or PP, is a 100 % synthetic fiber, transformed from 85% propylene, and used in a variety of applications. The monomer of polypropylene is propylene. Polypropylene is a by-product of petroleum. Polypropylene (PP) is a thermoplastic. It is a linear structure based on the monomer CnH2n. It is manufactured from propylene gas in presence of a catalyst such as titanium chloride. Beside PP is a by-product of oil refining processes. Most polypropylene used is highly crystalline and geometrically regular (i.e. isotactic) opposite to amorphous thermoplastics, such as polystyrene, PVC, polyamide, etc., which radicals are placed randomly (i.e. atactic). It is said that PP has an intermediate level of crystallinity between low density polyethylene (LDPE) and high density polyethylene (HDPE); On the other hand PP has higher working temperatures and tensile strength than polyethylene. Polypropylene chips can be converted to fiber/filament by traditional melt spinning.
Polypropylene (PP) is the first stereoregular polymer to have reached industrial importance. It is a thermoplastic, meaning that it becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. Polypropylene is processed into film for packaging and into fibres for carpets and clothing.
PP belongs to the group of polyolefins and is partially crystalline and non-polar. It has similar properties as polyethylene, but it is harder and more heat resistant. It is a white rugged material with a high chemical resistance. Poly propylene is the second-most widely produced commodity plastic (after polyethylene) and it is often used for product packaging and labeling.
Polypropylene is manufactured from propylene gas in presence of a catalyst such as titanium chloride. Polypropylene is a by-product of petroleum. You can find some more scientific info here.
PP has the following properties:
- low physical properties
- low heat resistance
- excellent chemical resistance
- translucent to opaque
- low price
- easy to process
Polypropylene chips can be converted to fiber/filament by traditional melt spinning process. The first fibres from polypropylene were introduced to the textile industry in the 1970s and have become an important member on the synthetic fibres market.
Polypropylene fiber displays good heat insulating properties and is highly resistant to acids, alkalies, and organic solvents. The fiber is sensitive to heat and light, but the resistance to these agents can be influenced by added stabilizers. Filaments and monofilaments are used in the manufacture of cables, nets, filter fabrics and upholstery. In staple form, the fiber is used in carpeting, blankets, outerwear fabrics, knitwear, and filter fabrics. Textured polypropylene fiber is mostly used for carpet manufacturing.
Growth in demand of PP is very high, and it is mainly due to its distinct technical features:
- light weight
- strong
- hydrophobic
- flexible
- has low thermal conductivity etc.
Because of all this, it is widely used to make undergarments, jackets for outerwear, swimming suits, filters, bags and diapers. It is used in many different industries, but one of the most popular is the manufacturing of carpet yarns. For example, most of the economical carpets for light domestic use are made from this fiber. The fiber is thermoplastic, resilient, light weight and resistant to mildew and many different chemicals.
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