Suitability of Recycled Polyester in Sportswear and Apparel Application

1.3 Scope

Sportswear, or activewear, encompasses clothing and footwear designed for sports and physical exercise, providing practicality, comfort, and safety for athletes. It can serve as both casual fashion and high-performance sportswear, depending on the design and intended use. The demand for functional and stylish sportswear has grown significantly due to increased awareness of fitness and health. Advances in textile technology have led to the development of moisture-wicking, breathable, and high-performance fabrics, while the rise of wearable devices such as fitness trackers and smartwatches has further boosted the demand for smart, functional activewear.

Recycled polyester (rPET) offers a sustainable alternative to traditional polyester. Its use helps reduce greenhouse gas emissions, energy consumption, and water usage, while also conserving virgin petrochemical resources. By diverting plastic waste from landfills and oceans, rPET reduces reliance on fossil fuels and promotes a circular economy. The recycling process for polyester consumes less energy and emits fewer greenhouse gases compared to the production of virgin polyester. Governments and organizations worldwide are supporting the use of recycled materials through policies and regulations, while many companies are adopting sustainability goals that include incorporating recycled polyester in their products.

Given its environmental and functional benefits, the application of rPET in sportswear provides an opportunity to combine sustainability with high-performance textile properties, making it a viable choice for modern activewear production.

2.1 General

Senthilkumar [1] conducted a study on the thermal comfort characteristics of layered knitted fabrics for sportswear, analyzing parameters such as thermal conductivity, air permeability, water vapor permeability, wicking ability, moisture absorbency, and drying rate. The study revealed that the thermal conductivity and air permeability of bi-layer knitted fabrics with one tuck point (Type 4) are significantly influenced by the fabric thickness and stitch density.

Furthermore, the water vapor permeability of the bi-layer fabric increases with a decrease in thickness and greater openness in the fabric structure. Among the tested fabrics, Type 4 bi-layer fabric with lower stitch density and minimal thickness exhibited the highest water uptake. It was also observed that the moisture absorbency of bi-layer knitted structures increases with higher stitch density and greater tightness factor, while the frequency of tuck stitches has a notable effect on the fabric’s moisture absorbency.

These findings indicate that fabric structure, stitch density, and thickness play critical roles in determining the comfort and moisture management properties of sportswear fabrics, which are essential for optimizing performance and wearer comfort during physical activities.

3.1 Materials

The materials used in this study include:

• Virgin polyester filament textured yarn: 150/48 denier

• Recycled polyester (rPET) filament textured yarn: 150/48 denier

Both yarns were sourced from spinning mills and were selected to ensure comparability in denier, texture, and suitability for knitting sportswear fabrics.

3.2 Plan of Work

The overall workflow of this study involves parallel processing of virgin polyester and recycled polyester (rPET) yarns to produce and evaluate knitted fabrics. The steps are as follows:

For Virgin Polyester Yarn (150 Denier):

1. Testing of Yarn – Assessing physical and mechanical properties of the yarn.

2. Winding of Yarn – Preparing yarn on bobbins for knitting.

3. Production of Knitted Fabric – Knitting suitable double jersey fabrics for sportswear applications.

4. Testing of Knitted Fabric Properties – Evaluating parameters such as moisture vapor transfer, air permeability, wicking, stitch density, abrasion, and pilling resistance.

For Recycled Polyester Yarn (150 Denier):

1. Testing of Yarn – Assessing physical and mechanical properties of the recycled yarn.

2. Winding of Yarn – Preparing yarn on bobbins for knitting.

3. Production of Knitted Fabric – Knitting suitable double jersey fabrics for sportswear applications.

4. Testing of Knitted Fabric Properties – Evaluating the same performance parameters as for virgin polyester fabrics.

This parallel approach allows a direct comparison between virgin and recycled polyester fabrics to determine the suitability of rPET for sportswear applications.

3.3 Methodology

The methodology of this study was designed to evaluate the suitability of recycled polyester (rPET) filament yarn in sportswear applications in comparison with virgin polyester yarn. The procedure includes the following steps:

1. Procurement of Yarn: Both recycled and virgin polyester filament yarns were sourced from spinning mills.

2. Yarn Testing: The yarns were tested to determine their physical and mechanical properties, including strength, fineness, and uniformity, ensuring consistency for fabric production.

3. Winding: The yarns were wound onto bobbins to prepare them for knitting.

4. Fabric Production: Using a knitting machine, double jersey fabrics suitable for sportswear T-shirts were produced from both types of yarn.

5. Fabric Testing: The knitted fabrics were evaluated for key performance properties such as abrasion resistance, moisture management, wicking, air permeability, stitch density, and pilling resistance.

6. Comparison and Analysis: The results of fabrics made from recycled and virgin polyester were compared to assess the suitability of recycled polyester for sportswear applications, highlighting any differences in performance and functionality.