Carpet can be made from many single or blended natural and synthetic fibres. Fibres are chosen for durability, appearance, ease of manufacture, and cost. In terms of scale of production, the dominant yarn constructions are polyamides (nylons) and polypropylene with an estimated 90% of the commercial market.
Nylon is the most common material for construction of carpets. Both nylon 6 and nylon 6-6 are used. Nylon can be dyed topically or dyed in a molten state (solution dying). Nylon can be printed easily and has excellent wearability. In carpets Nylon tends to stain easily because it possesses dye sites on the fibre. These dye sites need to be filled in order to give Nylon any type of stain resistance. As nylon is petroleum-based it varies in price with the price of oil.
Polypropylene is used to produce carpet yarns because it is inexpensive. It is difficult to dye and does not wear as well as wool or nylon. Polypropylene is commonly used to construct Berber carpets. In this case, polypropylene is commonly referred to as olefin. Large looped olefin Berber carpets are usually only suited for light domestic use and tend to mat down quickly. Berber carpets with smaller loops tend to be more resilient and retain their new appearance longer than large looped Berber styles. Commercial grade level-loop carpets have very small loops, and commercial grade cut-pile styles are well constructed. When made with polypropylene these styles wear very well, making them very suitable for areas with heavy foot traffic such as offices. Polypropylene carpets are known to have good stain resistance but not against oil based agents. If a stain does set, it can be difficult to clean. Commercial grade carpets can be glued directly to the floor or installed over a 1/4″ thick, 8-pound density padding. Outdoor grass carpets are usually made from polypropylene.
Wool and wool-blends
Wool has excellent durability, can be dyed easily and is fairly abundant. When blended with synthetic fibres such as nylon the durability of wool is increased. Blended wool yarns are extensively used in production of modern carpet, with the most common blend being 80% wool to 20% synthetic fibre, giving rise to the term “80/20”. Wool is relatively expensive and consequently a small portion of the market.
The polyester known as “PET” (polyethylene terephthalate) is used in carpet manufacturing in both spun and filament constructions. After the price of raw materials for many types of carpet rose in the early 2000s, polyester became more competitive. Polyester has good physical properties and is inherently stain-resistant because it is hydrophobic, and, unlike nylon, does not have dye sites. Color is infused in a molten state (solution dyeing). Polyester has the disadvantage that it tends to crush or mat down easily. It is typically used in mid- to low-priced carpeting.
Another polyester, “PTT” (Polytrimethylene terephthalate), also called Sorona, 3GT (Dupont), or Corterra (Shell), is a variant of PET. Lurgi Zimmer PTT was first patented in 1941, but it was not produced until the 1990s, when Shell Chemicals developed the low-cost method of producing high-quality 1,3 propanediol (PDO), the starting raw material for PTT Corterra Polymers.
Acrylic is a synthetic material first created by the Dupont Corporation in 1941 but has gone through various changes since it was first introduced. In the past Acrylic used to fuzz or pill easily, this happened when the fibres degraded over time and short strands broke away with contact or friction. Over the years Acrylics have been developed to alleviate some of these problems although the issues have not been completely removed. Acrylic is fairly difficult to dye but is colourfast, washable and has the feel and appearance of wool making it an ideal rug fabric.