Reasons why polyester fibers are preferable to polypropylene in geotextile applications

dkfiber2004
Nov 17
3 min read

Updated: Nov 19

Geotextiles used in various civil engineering fields—such as roads, railways, and dams—require long-term stability and durability. Therefore, selecting the appropriate nonwoven fiber material for geotextiles is crucial, as it directly affects construction quality and performance.

The two main materials used for geotextile nonwovens are polyester fiber (PET) and polypropylene fiber (PP). While both are widely utilized in geotextile nonwovens, the adoption of polyester fibers has been growing rapidly in global civil engineering projects.

In this post, we will look into the advantages of polyester and explain why the use of polyester fibers is increasing in the geotextile sector.

1. Superior Long-Term Durability (Creep Resistance)

Since geotextiles are subjected to continuous loads over long periods of time, long-term deformation resistance is a critical factor.

Polyester fibers exhibit low deformation under sustained loads and maintain structural stability over long periods of time. In contrast, polypropylene may experience deformation as time passes. In civil engineering applications, its tensile strength can decrease over time compared to polyester fibers.

In applications where load-bearing performance is essential—such as road foundations or soft ground reinforcement—nonwoven fabrics made with polyester provide a clear advantage.

2. Excellent High-Temperature Stability and Environmental Resistance

Polyester fiber offers superior stability under high temperatures and diverse environmental conditions for the following reasons:

A high melting point of approximately 255°C, providing excellent resistance to thermal deformation.
Lower structural degradation under UV exposure, acidic/alkaline environments, and general weathering.
Suitability for high-temperature soils, desert climates, and projects with prolonged sunlight exposure

In contrast, polypropylene has a much lower melting point of around 160°C, resulting in faster performance deterioration under elevated temperatures.

3. Superior Uniformity in Tensile Strength and Elongation

Polyester fiber provides highly consistent tensile strength and elongation properties.

Polyester fibers have an average tensile strength of 3.5–6.0 g/den and an average elongation of 30–60%. Based on these properties, polyester fibers maintain structural stability and deliver consistent performance.

Due to its manufacturing characteristics, polypropylene fiber exhibits greater variation in strength and does not offer the same level of long-term consistency as polyester.

Why deformation occurs more quickly in polypropylene (PP)

Then why does Polypropylene (PP) exhibit deformation more quickly than polyester?

PP is a semi-crystalline polymer with a very low glass transition temperature (Tg).

The temperature at which a polymer transitions from a rigid to a soft state is called the glass transition temperature (Tg). Polypropylene has a Tg of around 0°C, which is significantly lower than that of PET (approximately 70–80°C).

The low Tg of PP allows its molecular chains to move easily at room temperature, making the fibers more prone to deformation under long-term loads. As a result, PP fibers may exhibit increased elongation or a gradual reduction in tensile strength when subjected to sustained loading.
PP has weaker intermolecular attraction (bonding strength) than PET.

Polyester (PET) contains benzene-ring–based rigid molecular structures and high polarity, which create strong intermolecular bonding within the fiber. In contrast, PP has a simple carbon-chain structure, resulting in much weaker molecular cohesion.

Because of this, PP’s molecular chains slip more easily under long-term load, leading to faster deformation over time.
PP has low thermal stability and is vulnerable to temperature changes.

The melting point of PP is approximately 160°C, which is significantly lower than PET’s melting point of around 255°C.As a result, PP experiences faster performance degradation when temperatures rise, and in countries with high ground temperatures, the heat from the soil can become high enough that the melting point of PP becomes a critical limitation.

In summary, polyester staple fiber maintains excellent high-temperature stability and environmental resistance, ensuring that its tensile strength and elongation do not easily deform. As a result, it experiences minimal performance loss due to humidity or temperature fluctuations, making it far more suitable for geotextile applications compared to PP.

DK FIBER supplies a wide range of polyester staple fiber specifications optimized for civil engineering nonwoven fabrics. We are ready to recommend the most suitable fiber specifications for your planned geotextile products.

If you require specific specifications or samples, please feel free to contact us at any time.