Generally, nylon fabric is more resistant to heat damage compared to viscose spandex fabric.

Here's a more detailed comparison of the heat resistance of these two fabric types:

1. Fiber Composition:

   • Nylon is a synthetic polymer-based fiber that is inherently more heat-resistant than the regenerated cellulosic viscose fiber.
   • The molecular structure of nylon can withstand higher temperatures without significant degradation or deformation.

2. Melting Point:

   • Nylon has a higher melting point (around 220-260°C) compared to viscose, which has a lower melting point (around 150-220°C).
   • This means nylon can withstand higher temperatures before starting to melt or degrade.

3. Spandex Component:

   • The addition of spandex to viscose fabrics can slightly improve the heat resistance, as spandex is also a synthetic fiber.
   • However, the presence of the viscose component still makes the overall fabric less heat-resistant compared to a pure nylon fabric.

4. Thermal Stability:

   • Nylon fibers have a more stable molecular structure that can better maintain their physical and mechanical properties when exposed to heat.
   • Viscose, being a cellulosic fiber, is more susceptible to thermal degradation, which can lead to fiber weakening, discoloration, or even fabric shrinkage.

5. End-Use Considerations:

   • Nylon fabrics are commonly used in applications where they may be exposed to higher temperatures, such as in athletic wear, outdoor gear, or industrial textiles.
   • Viscose spandex fabric  are generally better suited for applications with lower heat exposure, such as in apparel, home textiles, or lightweight furnishings.

It's important to note that the specific heat resistance of a fabric can also be influenced by the fabric construction, finishing treatments, and any additional coatings or laminations applied to the fabric. Additionally, the duration and intensity of heat exposure can impact the degree of heat damage experienced by the fabric.