Abstract

This paper discusses the application of aerogel in polyester systems, with a focus on how different addition ratios of aerogel influence polyester properties. The method of introducing aerogel plays a critical role in determining whether polycondensation can proceed effectively. The study explores the polymerization and spinning processes of aerogel-modified PET copolyesters. When the aerogel content reaches 1%, the copolyester chip exhibit good appearance and spinnability, while the limiting oxygen index (LOI) of the fibers reaches 31.3%, indicating excellent flame-retardant performance. Furthermore, the application of aerogel-functional polyester chip in aerogel filament and staple fiber production is analyzed.

Keywords: PET; Aerogel; Polycondensation; Spinning; Limiting Oxygen Index; Aerogel Fiber

I. Introduction

Silica aerogel is a novel material characterized by a nanoporous structure. It is widely recognized as the lightest solid material in the world. With extremely low thermal conductivity, aerogel exhibits almost no shrinkage at temperatures below 600°C. It also possesses excellent fire resistance and demonstrates superhydrophobic properties similar to lotus leaves, effectively preventing electrochemical corrosion in industrial insulation processes.

In addition, aerogel features a large specific surface area and high porosity, along with ultra-low density and extremely high pore volume. These properties contribute to its outstanding thermal insulation performance, sound insulation capability, strong adsorption capacity, environmental friendliness, flame retardancy, and water repellency. Its adsorption capacity is more than five times that of diatomaceous earth, making it an excellent candidate for catalyst carriers and other advanced applications.

Aerogel-modified polyester chip represents an innovative combination of aerogel materials with conventional textile base materials. By incorporating aerogel into polyester during polymerization, functional polyester chip are produced. These chip can then be processed through spinning techniques to produce aerogel-based filament and staple fibers, which offer superior warmth retention and lightweight characteristics compared to conventional fibers.

1. Research on the Application of Aerogel in Polyester Chip

1.1 Experimental Equipment and Materials

The experiment utilized a 30 L polymerization reactor and a spinning machine.

  • Equipment: 30L polymerization reactor and spinning machine.

  • Aerogel Specifications: Average particle size of 4μm, density of 60~100 kg/m³, specific surface area of 600~800 m²/g, and thermal conductivity of 0.018~0.021 W/(m·K).

2. Results and Discussion

2.1 Impact of Aerogel Content on Polyester

The effect of aerogel content on the color coordinates (chroma) of polyester is shown in Table 1.

Table 1: Influence of Aerogel Content on Polyester Chroma

Aerogel Content (%) Polyester Chip Appearance
0.5 Milky White
1 Deep Yellow
2 Deep Yellow

As seen in Table 1, when the aerogel content is high, the polyester chip take on a deep yellow hue. During the reaction, aerogel is added alongside Purified Terephthalic Acid (PTA) and Ethylene Glycol (EG) for esterification and polycondensation; however, the aerogel itself does not participate in the chemical reaction.

At higher concentrations, aerogel molecules interfere with the contact between PTA, EG, and BHET (Bis(2-Hydroxyethyl) terephthalate). This disruption hinders the growth of the polyester molecular chain, leading to an increase in small molecular substances and significant yellowing of the appearance. Furthermore, due to its ultra-low density, large volumes of aerogel are difficult to physically incorporate into the melt. Consequently, for this study, an aerogel content of 0.5% was determined to be the optimal balance for performance and processability.

2.2 Catalyst Dosage

During polycondensation, metal ions in the catalyst coordinate with the oxygen on the aromatic carbonyl group attached to the benzene ring. In the synthesis of PET, internal hydrogen bonds form between the hydrogen of the hydroxyl group and the carbonyl oxygen, creating a cyclic complex. Under polycondensation conditions, the catalyst metal ions replace these hydrogen atoms and coordinate with the carbonyl oxygen, increasing the electrophilicity of the carbonyl carbon. This allows the oxygen from another hydroxyethyl ester group to bond with the carbon, extending the molecular chain.

Since aerogel contains trace metal ions and exhibits weak acidity, it provides a slight catalytic effect. Therefore, when adding aerogel, the amount of external catalyst should be appropriately reduced to maintain normal chip color and a stable reaction process.

2.3 Polymerization Process

  • 2.3.1 Addition Method: Both esterification and polycondensation were completed in the same reactor. Given that aerogel is a suspended solid fine powder, it was added during the initial slurry stage along with PTA and EG.

  • 2.3.2 Temperature Control: Water begins to evolve at an esterification temperature of 255°C. The total esterification time was 165 minutes, with temperature controlled between 230–245°C. Following esterification, the process enters low and high vacuum stages. Because aerogel particles increase the apparent viscosity of the melt by obstructing macromolecular movement, the discharge current is higher than that of conventional polyester. The final polycondensation temperature was set at 265°C with a reaction time of 136 minutes.
  • Thermal Analysis: Differential Scanning Calorimetry (DSC) showed a melting temperature of 257.04°C for the copolyester, indicating good spinnability.

2.4 Spinning Process

  • 2.4.1 Temperature and Speed: Although the intrinsic viscosity (IV) of Aerogel-PET is relatively low, the presence of inorganic particles requires a slightly higher spinning temperature than conventional PET. Spinning was stable at speeds of 2000 m/min and 2500 m/min with no breakages. However, at 2800 m/min (the standard speed for regular PET), spinning could not be maintained. Additionally, pack pressure rose rapidly due to the inorganic aerogel particles.

spinning speed
/(m·minˉ¹)		 Tensile strength
/(cN/dtexˉ¹)		 Stretch strain
/%		 Liner density
/dtex
2 000 1.21 214 193
2 500 1.33 165 173
  • 2.4.2 Drawing: Drawing was conducted across three rollers at temperatures of 75°C, 80°C, and 135°C, respectively. With a draw ratio of 2.0x, the process remained stable, yielding high-quality finished yarn.

2.5 Microscopic Analysis

Scanning Electron Microscopy (SEM) at 200,000x magnification revealed that the cross-sections of the chip and fibers are significantly rougher than standard polyester. The inclusion of aerogel particles prevents a smooth surface, resulting in a textured fiber that feels more like natural fiber to the touch.

2.6 Flame Retardancy

Knitted sock samples were tested according to the GB/T 5454-1997 standard. The samples achieved a Limiting Oxygen Index (LOI) of 31.3%. While the burning process still involves melting, the inherent thermal insulation properties of the aerogel significantly enhance the flame retardancy of the polyester matrix.

3. Section Summary

Synthesizing Aerogel-PET copolyester with 0.5% aerogel content results in a melting point of 257°C. Despite lower intrinsic viscosity, the spinnability is acceptable, and the resulting fibers possess excellent flame-retardant properties.

II. Introduction and Application of Functional Aerogel Polyester Chip

1. Introduction of Aerogel Polyester Chip

By perfectly combining high-efficiency thermal insulation aerogel powder with polyester during the polymerization stage, we produce aerogel-modified polyester chip. These chips retain the core characteristics of aerogel:

  • Low Thermal Conductivity: Tested consistently between 0.017 and 0.020 W/(m·K).

  • Superior Warmth: Performance significantly exceeds that of standard synthetic fibers.

Applications in Winter Sports: Clothing made from this material provides the necessary warmth while reducing fabric thickness and weight. This allows athletes to remain light and move freely in freezing conditions. Additionally, the garments are quick-drying, odor-resistant, easy to dye, and have low static electricity.

Introduction and Application of Functional Aerogel Polyester Chip

Introduction and Application of Functional Aerogel Polyester Chip

2. Functional Properties

2.1 High-Efficiency Warmth

The insulation of a fiber is proportional to the amount of static air trapped within its structure. While down’s quality is measured by “fill power” (trapped air), aerogel is composed of over 90% air by volume. This makes aerogel fiber the best-performing thermal insulation fiber currently available for the textile industry.

2.2 Lightweighting

The specific gravity of aerogel is extremely low (10–30 kg/m³). This reflects in the yarn; aerogel DTY (Drawn Textured Yarn) cakes are 16–20% less dense than standard polyester of the same specification under identical winding tension.

  • Economic Benefit: In textile manufacturing, one ton of aerogel filament yields 15–20% more length than a ton of regular polyester. This allows for the production of more fabric and more garments per ton of raw material, increasing profitability.

Aerogel Polyester Chip Functional Properties

Aerogel Polyester Chip Functional Properties

3. Applications of Aerogel Polyester Chip

3.1 Aerogel Polyester Filament

Produced using aerogel-modified masterbatches through a specialized spinning process.

  • Range of Use:

    1. Spinning into yarn to meet various textile fabric requirements.

    2. Direct weaving or knitting to produce high-performance functional fabrics.

3.2 Aerogel Polyester Staple Fiber

Produced from modified chip, these fibers share the same lightweight and insulating properties as filaments.

  • Range of Use:

    1. Yarn production for various textile blends.

    2. Direct use as filling material (stuffing).

    3. Raw material for thermal wadding, non-woven fabrics, and insulation bats.

3.3 Aerogel Aerospace Warm Fluff (Aerogel Insulation Cotton)

Processed through a proprietary technique using aerogel staple fibers as the primary raw material. Under identical conditions, its thermal performance exceeds that of “T-cotton” and “3M Thinsulate.”

  • Range of Use:

    1. Home Textiles: Quilts, pillows, and bedding.

    2. Apparel: Padded jackets, parkas, and heavy winter coats.

    3. Outdoor Gear: Sleeping bags, tent insulation layers.

    4. Automotive/Home: Seat cushions and upholstery.

III. Conclusion & Global Supply Services

As a premier professional supplier of Aerogel-Modified Polyester Chips, our company is dedicated to bridging the gap between advanced material science and textile industrial applications. By leveraging our expertise in functional polyester chip, we provide the textile industry with a transformative solution that balances ultra-thermal insulation, lightweighting, and excellent processability.

Our Aerogel Polyester Chip is engineered for high-performance filaments and staple fibers, offering a significant competitive edge for brands in the outdoor sports, aerospace, and protective clothing sectors. With a stable supply chain and rigorous quality control, we ensure that our materials meet the evolving demands of Industry 4.0.

Connect with Us

We invite global partners to explore the possibilities of aerogel technology. For technical specifications, wholesale inquiries, or custom sample development, please visit our official website or contact our sales team directly.

Website: https://www.polyestermfg.com/aerogel-polyester-chip/

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