1. Definition and properties:

Kevlar: This is the brand name of an aramid fiber material product developed by DuPont in the United States. The original name of the material is "poly(p-phenylene terephthalamide)", which is a new high-tech synthetic fiber with high strength, high wear resistance and high tear resistance.

Aramid fiber: Also known as aromatic polyamide fiber, it is a new high-tech synthetic fiber. It belongs to the same amide fiber as ordinary nylon, but the amide bond of aramid is connected to the benzene ring, giving it unique properties.

2. Relationship:

Kevlar is a brand or product of aramid fiber. Specifically, it is the brand name of para-aramid fiber developed by DuPont.

Aramid fiber is a broader concept, which includes many different types of fibers, of which para-aramid fiber (PPTA) and meta-aramid fiber (PMIA) are the two main types. Kevlar is a specific brand of PPTA type.

3. Performance and application:

Kevlar is known for its high strength, high wear resistance and high tear resistance. Its strength is 5 times that of steel of the same quality, but its density is only one-fifth of that of steel. It is widely used in military, protection, aerospace and other fields, such as tanks, armored vehicles, bulletproof vests, optical fiber protection, etc.

Aramid fiber is also known for its high strength, high modulus, high temperature resistance, acid and alkali resistance and other properties. Its strength is 5 to 6 times that of steel wire, and its modulus is 2 to 3 times that of steel wire or glass fiber. It also occupies an important position in high-performance fibers and is widely used as a reinforcement for various high-performance composite materials.

In summary, Kevlar is a brand or product of aramid fiber. The two overlap in properties, performance and applications, but are not completely equivalent.