First Synthetic Fibre:
The first synthetic fibre to be developed was rayon. Rayon is considered a semi-synthetic fibre because it is derived from cellulose, which is a natural polymer found in plants. In the late 19th century, a French chemist named Hilaire de Chardonnet invented the first commercially successful method of producing rayon. He discovered that cellulose could be dissolved in a solution of copper sulfate and ammonia, and then extruded through small holes to form filaments. These filaments were then spun into yarn and woven into fabric.

First Fully Synthetic Fibre:
The first fully synthetic fibre to be developed was nylon. Nylon was invented by a team of researchers at the chemical company DuPont in the United States. In the 1930s, Wallace Carothers and his team were experimenting with different types of polymers when they discovered that a combination of adipic acid and hexamethylenediamine could be polymerized to form a strong, flexible, and heat-resistant fibre. This fibre was given the name nylon, and it quickly became popular for its versatility and durability.

Comparison between Rayon and Nylon:

Composition:
Rayon is derived from cellulose, a natural polymer found in plants, while nylon is a completely synthetic polymer.

Production Process:
Rayon is produced by dissolving cellulose in a chemical solution and then extruding it into filaments, which are then spun into yarn. Nylon, on the other hand, is produced through a polymerization process that involves combining different chemical compounds to form a synthetic polymer.

Properties:
Rayon has a soft and silky texture, and it closely resembles natural fibres like cotton and silk. It is also highly absorbent and comfortable to wear. Nylon, on the other hand, is a strong and durable fibre that is known for its high tensile strength and resistance to abrasion.

Uses:
Rayon is commonly used in the production of clothing, including dresses, shirts, and blouses. It is also used to make bed linens, curtains, and upholstery fabrics. Nylon, on the other hand, is widely used in the production of various consumer products, such as clothing, carpets, ropes, and fishing nets. It is also used in the automotive industry for the production of parts like seat belts and airbags.

In conclusion, rayon was the first synthetic fibre to be developed, although it is derived from natural cellulose. Nylon was the first fully synthetic fibre, and it revolutionized the textile industry with its strength, durability, and versatility. Both fibres have different properties and applications, and they continue to be widely used in various industries today.