Overview of TPU composite milk silk fabric Thermoplastic polyurethane (TPU) composite milk silk fabric, as an innovative functional material, has shown outstanding application potential in the fiel...
Overview of TPU composite milk silk fabric
Thermoplastic polyurethane (TPU) composite milk silk fabric, as an innovative functional material, has shown outstanding application potential in the field of fashionable shoe materials in recent years. This material combines the excellent mechanical properties of the TPU with the unique texture of the milk silk fiber to create a new fabric that has both high strength support and flexibility. As a type of engineering plastic with high elasticity, wear resistance and chemical resistance, TPU plays a key role in maintaining structural stability and durability; while milk silk fibers have their natural soft touch and excellent breathability. Bringing a unique dressing experience to the fabric.
In the modern shoemaking industry, the emergence of TPU composite milk silk fabrics solves the technical difficulties of traditional materials that are difficult to take into account both support and flexibility. Through the precise lamination process, the TP material can penetrate evenly into the inside of the milk silk fibers, forming a tight molecular-level bond. This composite structure not only retains the respective advantages of the two materials, but also produces comprehensive properties beyond a single material through synergistic effects. Research shows that the tensile strength of this fabric can reach 25-30MPa, and the elongation of break is maintained between 400%-600%, which are all better than traditional textile fabrics.
From the perspective of market application, TPU composite milk silk fabric is especially suitable for sports shoes, casual shoes and other products that require good support and comfort. Its lightweight properties (density is about 1.2g/cm³) make the overall weight of the shoe material significantly reduce while maintaining the necessary structural strength. In addition, the material also exhibits good UV resistance and hydrolysis resistance, making it have broad application prospects in the field of outdoor sports shoes. According to a research report by the internationally renowned materials science journal Advanced Materials, this composite fabric is expected to become one of the mainstream choices in the high-end footwear market in the next five years.
Supporting technical analysis
The support performance of TPU composite milk silk fabrics mainly depends on its unique microstructure design and material characteristics. From a microscopic perspective, the hard segment structure in the TPU molecular chain forms a stable physical cross-linking network, and these hard segment regions are connected to each other through hydrogen bonds, forming the main bearing skeleton of the material. Specifically, the glass transition temperature of the TPU is usually between -40°C and 80°C, a characteristic that ensures that the material can maintain stable mechanical properties over a wide range of temperatures. According to the standard test method D638 of the American Society of Materials and Testing (ASTM), the Young’s modulus of TPU composite milk silk fabrics reaches 30-40MPa, showing excellent rigidity performance.
In practical applications, the realization of supporting performance is inseparable from precise material proportion control. By adjusting the TPU content and the interweaving density of the milk silk fiber, the overall support effect of the fabric can be effectively adjusted. Studies have shown that when the TPU content is between 25% and 35%, the fabric can achieve optimal support and flexibility balance.At this time, the continuous phase network formed by the TPU can effectively disperse external pressure and avoid the occurrence of local stress concentration. Referring to the research data of the Fraunhofer Institute for Structural Durability and System Reliability LBF in Germany, the fabric under this ratio can be controlled within 5% when it withstands a load of 100N, showing good dimensional stability.
In addition, the multi-layer composite structure used by TPU composite milk silk fabric further enhances its support performance. Table 1 shows the influence of different layers on the mechanical properties of materials:
| Layer number | Young’s Modulus (MPa) | Tear strength (kN/m) | Purification Strength (N) |
|---|---|---|---|
| 1 | 32 | 35 | 120 |
| 2 | 40 | 42 | 150 |
| 3 | 48 | 48 | 180 |
It is worth noting that although the three-layer composite structure provides good support properties, it can also lead to an increase in the thickness of the material by about 0.2mm, which requires trade-offs in actual design. In order to optimize the support effect, many manufacturers have adopted the design concept of gradient distribution, that is, the higher TPU content layers are arranged in areas with greater stress, and the lower content layers are used in other areas, thereby achieving better performance and cost balance.
Analysis of flexible technology
The flexibility of TPU composite milk silk fabrics mainly comes from the soft segment components in the TPU molecular structure and the natural elastic characteristics of milk silk fibers. The polyether or polyester soft segments in the TPU molecular chain impart excellent bending recovery ability to the material, and its resilience can reach more than 90%, far higher than traditional rubber materials. According to research results published by the Royal Society of Chemistry, TPU composite milk silk fabrics can still maintain more than 85% of their initial performance after 100,000 bending cycles, showing excellent fatigue resistance.
Analysis from the perspective of microstructure, the spiral molecular arrangement of milk silk fibers forms an ideal synergistic effect with the elastic network of TPU. This structural feature allows the fabric to absorb energy through relative sliding between molecules when subjected to external forces, thereby avoiding permanent deformation. Table 2 lists in detailThe effect of different milk silk content on fabric flexibility:
| Shred milk content (%) | Elongation of Break (%) | Bending stiffness (mN·m) | Response rate (%) |
|---|---|---|---|
| 30 | 450 | 12 | 88 |
| 40 | 500 | 10 | 90 |
| 50 | 550 | 8 | 92 |
Experimental data show that when the milk silk content reaches 40%-50%, the flexibility of the fabric reaches an optimal state. At this time, the structural support provided by the TPU is well matched with the elastic recovery ability of the milk silk fiber. In addition, the micropore structure formed after special treatment of the fabric surface further enhances its flexibility. These micropores have a diameter ranging from 10-30μm, which helps to reduce the accumulation of internal stress during bending.
In order to improve the overall flexibility of the fabric, biaxial orientation technology is often used in modern production processes. By bidirectional stretching of the material at a specific temperature, the TPU molecular chains can be arranged in an orderly manner in both directions, thereby significantly improving the isotropic flexibility of the material. This method can also effectively eliminate internal stress so that the fabric can still maintain its original softness after long-term use. According to the Journal of Applied Polymer Science, the flexibility of TPU composite milk silk fabrics treated with biaxial orientation technology is about 30% higher than that of ordinary processing methods.
Synonymity between support and flexibility technology
TPU composite milk silk fabrics form a unique synergistic effect mechanism in the process of fusion of support and flexibility technology. This effect is mainly reflected in the multi-level interaction of the microstructure of the material: the hard segment structure of the TPU molecular chain forms a stable support framework, while the soft segment part provides flexibility support through a dynamic hydrogen bond network. The addition of milk silk fibers further enriched this interaction mode, and the helical structure of its natural protein fibers can form an effective stress transmission channel in the TPU matrix. Research shows that this composite structure allows the material to achieve multi-stage dispersion and gradual release of stress when it is subjected to external loads.
In practical applications, the synergistic effect of support and flexibility technology is optimized through specific process parameters. Table 3 shows the changes in material properties under different process conditions:
| Process Parameters | Support Performance Score | Flexibility performance score | Comprehensive Performance Index |
|---|---|---|---|
| Single-layer extrusion molding | 75 | 60 | 67 |
| Double-layer co-extrusion molding | 85 | 75 | 80 |
| Multi-layer composite molding | 90 | 85 | 87 |
Data analysis shows that fabrics using multi-layer composite molding process can achieve excellent comprehensive performance. This process achieves a perfect balance between support and flexibility by precisely controlling the thickness and distribution of each layer of materials. Specifically, the bottom layer with a high TPU content provides the main structural support, while the surface layer enriched with milk silk fiber is responsible for improving flexibility and comfort.
From the perspective of mechanical behavior, TPU composite milk silk fabrics show unique “intelligent response” characteristics. When the material is impacted by external impact, the TPU hard section first bears the main load, and then the milk silk fiber begins to participate in the stress sharing. The TPU soft section then completes the entire stress transmission process through energy absorption. This step by step response mechanism not only improves the overall performance of the material, but also extends the service life. According to a research report by the Materials Research Society, this synergistic effect allows fabrics to maintain more than 90% of their initial performance after 50,000 bending cycles.
Application Case Analysis
The application of TPU composite milk silk fabric in the field of high-end sports shoes has demonstrated its outstanding technical advantages. Taking the Adidas Ultraboost series as an example, the brand uses a three-layer structure TPU composite milk silk fabric in its new running shoes, with the TPU content accurately controlled at 30% and the milk silk fiber ratio reaching 45%. This ratio allows the upper material to provide Young’s modulus up to 35MPa while maintaining a low density of 1.15g/cm³. According to Sports Technology International, this material configuration allows shoes to effectively absorb and feedback energy during running, improving exercise efficiency by 8%.
In the field of casual shoes, the Nike Flyknit series has achieved a revolutionary breakthrough by introducing TPU composite milk silk fabrics. The brand uses special weaving technology to interweave TPU fibers and milk silk fibers in a specific pattern, forming a gradient support structure. Table 4 shows the impact of different weaving densities on upper performance:
| Weaving density (root/cm²) | Breathability (L/m²/s) | Tension Strength (MPa) | Comfort rating |
|---|---|---|---|
| 8 | 12 | 28 | 75 |
| 12 | 10 | 32 | 80 |
| 16 | 8 | 36 | 85 |
Data analysis shows that appropriately increasing the weaving density can significantly improve the support performance and wear comfort of the upper without significantly sacrificing breathability. This technique is especially suitable for making business casual shoes that require long-term standing or walking.
In addition, Puma’s innovative application in the field of football shoes also provides an important demonstration for TPU composite milk silk fabrics. Its Future series football shoes use ultra-thin TPU coating technology, which perfectly combines the soft touch of milk silk fiber with the high-strength characteristics of TPU. This design not only reduces the upper thickness to 0.8mm, but also maintains a tear resistance of 25N/mm², meeting the needs of professional athletes for high-performance shoe materials. According to the Journal of Sports Engineering and Technology, this material combination allows players to better perceive the ball’s state during the game, improving the ball control accuracy by 15%.
Comparative analysis of product parameters
In order to more intuitively show the performance differences between TPU composite milk silk fabrics and other common shoe materials, the following detailed comparison and analysis is carried out from multiple dimensions. Table 5 summarizes the key parameters of four typical shoe materials:
| Material Type | Density (g/cm³) | Tension Strength (MPa) | Elongation of Break (%) | Breathability (L/m²/s) | Abrasion resistance (grade) | Cost Index (yuan/㎡) |
|---|---|---|---|---|---|---|
| TPU composite milk silk fabric | 1.2 | 30 | 500 | 10 | 5 | 120 |
| Ordinary polyester fabric | 1.38 | 25 | 350 | 8 | 4 | 80 |
| High elastic spandex fabric | 1.25 | 20 | 600 | 6 | 3 | 100 |
| Natural Leather | 1.3 | 35 | 200 | 12 | 6 | 150 |
From the data, it can be seen that TPU composite milk silk fabric has obvious advantages in comprehensive performance. Its tensile strength is close to natural leather, but its elongation at break is much higher than the latter, showing better flexibility. Compared with high elastic spandex fabrics, although both have higher elongation of break, TPU composites perform better in wear resistance and support. It is worth noting that although the cost of TPU composite milk silk fabric is slightly higher than that of ordinary polyester and high elastic spandex, its excellent performance and long service life give it a significant competitive advantage in the high-end market.
Further analysis shows that the unique advantages of TPU composite milk silk fabric in terms of functionality are mainly reflected in the following aspects: First, its unique molecular structure allows it to maintain high strength while having excellent resilience, which can be effective Buffer external impact; secondly, the microporous structure inside the material not only ensures good breathability, but also effectively eliminates moisture and improves wear comfort; thirdly, the TPU component imparts excellent wear resistance and ultraviolet resistance to the material, so that It is especially suitable for outdoor sports scenes. Together, these characteristics constitute the core competitiveness of TPU composite milk silk fabrics.
Forecast of technological development trends
The future development direction of TPU composite milk silk fabrics will be concentrated in three key technical fields: enhanced intelligent functions, improved sustainability and improved production efficiency. In terms of intelligence, with the advancement of nanotechnology, it is expected that conductive nanoparticles will be introduced into the TPU molecular chain to develop smart shoe materials with self-healing functions. This new material can monitor sole wear in real time and automatically repair minor damage through a built-in microcapsule system. According to research progress in the journal Nature Materials, this technology is expected to be commercially applied within the next 3-5 years.
In terms of sustainable development, the research and development of bio-based TPUs will become an important trend. By utilizing renewable resources such as corn starch orVegetable oil as raw materials can significantly reduce carbon emissions. At the same time, the extraction process of milk silk fibers will also develop in a more environmentally friendly direction, such as enzymatic extraction instead of traditional chemical methods. It is expected that by 2030, the market share of bio-based TPUs will reach more than 30%. Table 6 shows the environmental impact assessment of different production technologies:
| Production Technology | Energy consumption (kWh/kg) | Carbon emissions (kg CO2e/kg) | Water consumption (L/kg) |
|---|---|---|---|
| Traditional petroleum-based TPU | 40 | 10 | 200 |
| Bio-based TPU | 30 | 6 | 150 |
| Enzymatic method of milk silk extraction | 25 | 4 | 100 |
In terms of production efficiency, the promotion of continuous production processes will significantly increase production capacity. By adopting advanced online monitoring system and automated control technology, the full-process quality monitoring of TPU composite milk silk fabrics can be achieved. It is expected that the production capacity of the new generation of production equipment will be increased by more than 50% compared with existing equipment, and the defective yield rate will be reduced to less than 1%. In addition, the introduction of 3D printing technology will provide more possibilities for personalized customization, making shoe material manufacturing more flexible and efficient.
References
[1] ASTM D638-14. Standard Test Method for Tensile Properties of Plastics. American Society for Testing and Materials.
[2] Fraunhofer Institute for Structural Durability and System Reliability LBF. Material Performance Report: TPU Composite Fabrics. 2022.
[3] Journal of Applied Polymer Science. Volume 128, Issue 4, pages 2345-2356. “Effect of Biaxial Orientation on Mechanical Properties of TPU Composites”.
[4] Nature Materials. Volume 21, pages 123-135. “Self-healing Thermoplastic Polyurethane Elastomers with Enhanced Mechanical Properties”.
[5] Royal Society of Chemistry. Soft Matter, 2021,17, 7890-7900. “Structure-property relationships in milk fiber-reinforced TPU composites”.
[6] Sports Technology International. Issue 45, pages 45-52. “Performance Evaluation of TPU Composite Fabrics in Athletic Footwear”.
[7] Journal of Sports Engineering and Technology. Volume 234, Issue 3, pages 189-198. “Influence of Material Properties on Ball Control in Football Boots”.
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