What is the difference between polypropylene FDY yarn and polyester FDY yarn?

Raw material source and chemical structure

polypropylene FDY yarn:

The raw material of polypropylene FDY yarn is propylene. It is a polypropylene fiber made by polymerizing propylene. The molecular chain of polypropylene is mainly composed of carbon hydrogen (C-H) bonds, and the molecular chain is relatively regular, making it a linear polymer compound. This chemical structure gives polypropylene fibers a relatively light weight.

polypropylene FDY yarn:

The main raw materials for polyester FDY yarn are terephthalic acid (PTA) and ethylene glycol (EG). Polyester is formed through condensation reaction, and its chemical structure is composed of repeating units connected by ester bonds (- COO -) to the benzene ring. This structure containing benzene rings gives polyester fibers high strength and modulus.

physical property 

Strength and modulus:

polypropylene FDY yarn: The strength of polypropylene FDY yarn is generally lower than that of polyester FDY yarn. For example, at the same linear density, polyester FDY yarn can withstand greater tensile strength, with a tensile strength of around 3-7cN/dtex, while polypropylene FDY yarn typically has a tensile strength of around 2-5cN/dtex. This is because the molecular chain of polyester contains a benzene ring structure, which makes the interaction force between the molecular chains stronger, thus having higher strength and modulus.

Elastic response rate:

polypropylene FDY yarn: polypropylene FDY yarn has a good elastic recovery rate, especially at lower stretching levels. This makes it perform well in some application scenarios that require elasticity, such as in the elastic parts of some sportswear.

Polyester FDY yarn: The elastic recovery rate of polyester FDY yarn is relatively low, but its dimensional stability is better than that of polypropylene FDY yarn in high temperature environments. For example, when making ropes for industrial use or products that require long-term shape retention, polyester FDY yarn has more advantages.

Density and weight:

polypropylene FDY yarn: The density of polypropylene FDY filament is relatively low, about 0.91g/cm 3, and it is the lightest among common synthetic fibers. This gives it an advantage in making lightweight products, such as some outdoor portable tents, where using polypropylene FDY yarn can reduce overall weight.

Polyester FDY yarn: The density of polyester FDY yarn is about 1.38g/cm 3, which is relatively heavy. However, this heavier characteristic also has benefits in certain applications, such as making curtains and other home textile products that require a certain sense of weight, which can make the product more hanging.

Glossiness:

polypropylene FDY yarn: The glossiness of polypropylene FDY yarn is relatively soft, and the surface is relatively smooth. If a high gloss effect is required, special post-processing techniques may be needed to enhance the gloss.

Polyester FDY yarn: Polyester FDY yarn can have good glossiness, especially after being treated with light. Its luster is bright and long-lasting, which is more advantageous in making decorative fabrics or high-end clothing fabrics.

Chemical properties

Chemical resistance:

Polypropylene FDY yarn: Polypropylene FDY yarn has good resistance to acid and alkali. It is relatively stable in general acidic and alkaline environments and is not easily damaged by chemical reactions. For example, in the early stages of some chemical filtration, polypropylene FDY fibers can resist a certain concentration of acidic and alkaline solutions.

Polyester FDY yarn: Polyester FDY yarn has good acid resistance, but is relatively fragile in alkaline environments. In concentrated alkaline solution, the ester bonds of polyester fibers may undergo hydrolysis reaction, leading to a decrease in fiber strength. However, in weak alkaline and most acidic environments, polyester FDY yarn can still maintain good chemical stability.

Moisture absorption performance:

Polypropylene FDY yarn: Polypropylene FDY yarn has poor moisture absorption performance and almost no moisture absorption. This allows it to remain dry in some humid environments, but it may also result in slightly lower comfort when worn, such as making close fitting clothing that may feel stuffy.

Polyester FDY yarn: The moisture absorption performance of polyester FDY yarn is not strong, and its moisture regain is relatively low, generally around 0.4%. However, through some special fiber modification or fabric post-treatment processes, its moisture absorption and breathability can be improved to a certain extent.

combustion performance

Polypropylene FDY filament: Polypropylene FDY filament is flammable, with a blue flame when burned. After leaving the fire source, it will continue to burn and there may be droplets. This is because the main component of polypropylene is composed of hydrocarbons, which are easily combustible.

Polyester FDY filament: Polyester FDY filament shrinks when burned, and the flame appears yellow white with black smoke produced. It may continue to burn for a short period of time after leaving the fire source, but the burning speed is slightly slower than that of polypropylene FDY yarn. The ash of polyester fiber after combustion is a black hard block, which is due to the presence of benzene rings and other components in its chemical structure. The residue after combustion is different from that of polypropylene.

Differences in application fields

Polypropylene FDY filament:

Due to its lightweight, chemical resistance, and good elastic recovery rate, polypropylene FDY yarn is mainly used to make outdoor equipment (such as tents, sleeping bags), elastic parts of sportswear, industrial ropes (especially in situations where weight is required), and some chemical filtration materials.

Polyester FDY yarn:

Polyester FDY yarn is widely used in clothing fabrics (especially formal and high-end fashion), home textiles (such as curtains and bedding), industrial conveyor belts, ropes and other fields due to its high strength, good glossiness and dimensional stability. In products that require high-end appearance, high strength, and long-term stability, polyester FDY yarn is often the preferred choice.

Shanghai Jinci Industrial Co., Ltd, founded in March 2006, is a large entity company specializing in the production and sales of polypropylene fiber (PP yarn). The company's products include polypropylene general filament, PP high-strength yarn, polypropylene light body filament, polypropylene twist filament, polypropylene hollow filament, polypropylene fluorescent filament, polypropylene luminous filament, polypropylene flame retardant filament, polypropylene air variable filament, etc.