How does TPU melt penetration improve the interfacial bonding strength of polyester pongee-nylon warp knitted composite fabrics?

In the development of functional composite textile materials, interfacial bonding strength is a key factor in determining product durability and performance stability. Traditional gluing or laminating processes often rely on the physical attachment of adhesives to the surface of fabrics, which can easily lead to delamination due to repeated friction or washing, limiting the reliability of materials in high-intensity application scenarios. Using TPU (thermoplastic polyurethane) as the middle layer and realizing the composite of 100D high-elastic polyester pongee and nylon warp knitted fabrics through melt penetration technology fundamentally changes the microscopic mechanism of interfacial bonding, enabling the composite fabric to achieve qualitative improvements in peel strength, washability and dynamic adaptability.

The core of the TPU melt penetration process lies in its thermoplastic properties. When TPU is heated to a molten state, its molecular chain fluidity is enhanced, and it can penetrate into the fiber gaps of polyester pongee and nylon warp knitted fabrics under pressure, rather than just staying on the surface. This process is similar to "anchoring" at the microscopic scale. After cooling and solidification, the TPU melt forms a mechanical interlocking structure with the two fibers, rather than relying on the chemical bonding of traditional glue. This bonding method significantly improves the interface's anti-peeling ability. Even under repeated stretching or bending, the composite layers can remain stable, avoiding interlayer separation caused by stress concentration.

Compared with traditional gluing processes, the advantages of TPU melt penetration are not only reflected in higher bonding strength, but also in its excellent environmental stability. Traditional adhesives are prone to hydrolysis or aging in hot and humid environments, resulting in bonding failure, while TPU itself has good water resistance and chemical resistance, allowing the composite fabric to maintain structural integrity after multiple machine washings or sweat erosion. In addition, the elastic modulus of TPU can be adjusted, so that it can fully fill the fiber gaps during the composite process without over-hardening, thereby retaining the high elastic properties of polyester pongee and the wear resistance of nylon warp knitting, achieving a material performance that is both rigid and flexible.

From the perspective of materials science, the success of the TPU melt infiltration process depends on three key factors: the accuracy of temperature control, the uniformity of pressure distribution, and the pretreatment of the fiber surface. Too high a temperature may cause excessive degradation of TPU and affect the bonding strength; insufficient temperature will result in insufficient penetration and the formation of a weak interface layer. The pressure must ensure uniform penetration of the TPU melt to avoid local glue deficiency or uneven thickness. In addition, surface treatment of polyester pongee and nylon warp knitted fabrics before lamination (such as plasma or chemical activation) can further enhance the affinity between the fiber and TPU and optimize the interface bonding effect.

The breakthrough of this process is that it not only solves the interlayer separation problem of traditional composite fabrics, but also gives the material a new functional dimension through microstructure design. For example, TPU can form a microporous structure during the infiltration process, so that the composite fabric has a certain breathability while maintaining windproof and water-proof, avoiding stuffiness. In addition, due to the elastic buffering effect of TPU, the composite fabric can effectively disperse stress during dynamic stretching, reduce fatigue damage, and extend service life.