Any fiber can be tufted in a good, durable manner or not, therefore construction is still the largest determining factor on how well any carpet performs.  Nylon, Polyester (abbreviated as PET), Triexta, and polypropylene (or olefin) are all synthetic polymers derived from petroleum that are processed to be carpet yarns. 

While a good construction can be made of any of the face fibers, there are some individual characteristics to the different fibers.  They are as follows:

Nylon Carpet Fiber

Think of nylon as a premium carpet fiber with terrific product benefits:

Strong, excellent resistance to abrasion, crush and wear, insects, molding, mildew, rot, and many chemicals.

Easy to maintain and dye, and colorfast. 

Durable

Versatile styling possibilities

Nylon is durable and static-free maintains fiber height and resists soiling or staining.

Polyester (PET) Carpet Fiber  

Polyester is known for its luxurious look, feel, and wonderful selection of bright, bold colors and styles. Many of the super-soft carpet introductions feature polyester fiber. These carpet styles are ideal for lower-traffic areas such as bedrooms, offices, or TV rooms.

 Many polyester carpets, called PET (polyethylene terephthalate) contain content made of recycled plastics such as water bottles. This can make polyester a “green” option and also helps strengthen the fiber to help it last longer. Polyester is also naturally stain-resistant and easily recyclable.

Since polyester carpet isn’t crush-resistant, it will wear down and lose texture faster in high-traffic areas faster than wool or nylon. Although less expensive than other fibers initially, polyester carpeting may have to be replaced more frequently.

However, it is more stain-resistant than nylon carpet and at least as resistant to mold and mildew. It is also non-allergenic.

PTT (Triexta Polyester) Carpet Fibers - also known as Smartstrand and Corterra

PTT (Polytrimethylene Terephthalate) is a polyester fiber with better resilience than PET. Mohawk's PTT is called Smartstrand whereas Shaw's is called Corterra.

 PTT features good resilience and excellent inherent stain resistance, although it is susceptible to dry and oily soil substances. It is also soft.  

Polypropylene or Olefin Carpet Fiber

Olefin offers good stain and moisture resistance, but scores below nylon and polyester for wearability. Unlike nylon, it isn't resilient and can easily crush and lose texture. It is best suited for loop pile construction or high, very dense cut piles where crushing isn't a concern.

 Unlike other fiber types, polypropylene won't absorb water, leading to two major benefits:

It must be solution-dyed. Solution dyeing is a process in which color is actually built into the fiber when it is formed making the color an inherent part that cannot be removed from the fiber. As a result, color doesn't fade, even when exposed to intense sunlight, bleaches, atmospheric contaminants, or other harsh chemicals or elements.

It lends itself to colorful styles and designs.

It's easy to clean.

It is ideal for installations where mildew is a concern (i.e., think basements and outdoor carpets or rugs).

Wool Carpet

For the ultimate in carpet, there's wool. Not only is it truly natural but it has many natural benefits:

Natural soil resistance (although not inherently stain-resistant)

Green, renewable, and environmentally friendly (including biodegradable)

Soft and luxurious to the touch

Naturally flame-resistant

It's non-allergenic.

Resilient and durable enough to perform well in high-traffic areas without wearing out