In building insulation and HVAC systems, rubber and plastic insulation materials are widely used due to their flexible structure and stable performance. One of the important indicators for measuring their insulation effect is thermal conductivity. This article will systematically explain this from the aspects of material structure, heat transfer mechanism, and influencing factors.

I. The Significance of Thermal Conductivity in Rubber and Plastic Insulation Materials

Thermal conductivity is a key parameter for measuring a material's ability to conduct heat:

The lower the value, the slower the heat passes through the material.

The more stable the insulation performance, the more significant the energy-saving effect.

In the HVAC and building fields, the thermal conductivity of rubber and plastic materials directly affects the actual insulation effect of pipes, ducts, and equipment.

II. Typical Performance Characteristics of Rubber and Plastic Thermal Conductivity

Rubber and plastic insulation materials are generally low-thermal-conductivity closed-cell insulation materials. Their thermal conductivity has the following characteristics:

Stable performance at normal temperature

Strong adaptability to humidity changes

Minimal performance degradation over long-term use

Compared with some fibrous materials, rubber and plastic are more likely to maintain consistent thermal conductivity under moisture-proof conditions.

III. Structural Mechanism of Thermal Conductivity Formation in Rubber and Plastics

1. Inhibition of Heat Conduction by Closed-Cell Structure

Rubber and plastic materials consist of numerous independent, closed air bubbles:

Gas is confined within tiny spaces.

Air convection is essentially eliminated.

Heat is primarily conducted through molecules.

Since the thermal conductivity of gases is much lower than that of solids, the closed-cell structure is the core reason for the low thermal conductivity of rubber and plastics.

2. Influence of Solid Skeleton Proportion on Thermal Conductivity

The solid portion in rubber and plastic materials has a continuous but non-dense structure:

The solid heat conduction path is dispersed.

Heat flow must bypass the bubble structure.

Overall thermal conductivity is reduced.

With appropriate formulation and foaming process, the contribution of solid thermal conductivity can be effectively controlled.

3. Flexible Continuous Structure Reduces Thermal Bridges

Rubber and plastic materials possess good flexibility:

They can fit tightly to pipe and equipment surfaces.

This reduces installation gaps.

It lowers the probability of thermal bridge formation.

This makes it easier to approach the design thermal conductivity in actual engineering than the theoretical value.

IV. Main Factors Affecting the Thermal Conductivity of Rubber and Plastics

1. Foaming Structure and Closed-Cell Ratio

A higher closed-cell ratio results in more stable gas insulation.

An increased open-cell ratio increases heat conduction channels.

2. Density and Compression Ratio

Excessive compression increases the proportion of solid thermal conductivity.

Insufficient density may affect structural stability.

A suitable density is key to balancing thermal conductivity and service life.

3. Operating Temperature Range

With temperature changes:

The thermal conductivity will change to some extent.

Within the designed operating temperature range, performance remains relatively stable.

4. Moisture Content and Ambient Humidity

Rubber and plastic materials have low water absorption:

Moisture does not easily penetrate the internal structure.

The thermal conductivity does not easily increase significantly due to moisture.

This is also an important reason why rubber and plastics are widely used in cold water systems.

V. Practical Significance of Rubber and Plastic Thermal Conductivity in Engineering Applications

From an engineering perspective, the advantages of rubber and plastic thermal conductivity are:

Effectively reducing heat loss

Reduces the risk of condensation in pipes

Improves system operational energy efficiency and stability

Under reasonable thickness design and standardized construction conditions, its thermal conductivity can remain stable over a long period.

VI. Comparison Logic of Rubber and Plastic Thermal Conductivity with Other Insulation Materials

In practical material selection, rubber and plastic are often compared with the following materials:

Glass wool

Rock wool

Aerogel composite materials

Rubber and plastic do not pursue extremely low thermal conductivity, but rather emphasize:

Achieving a comprehensive balance between thermal conductivity, moisture resistance, and construction adaptability.

In summary, the high thermal conductivity of rubber and plastic relies on its highly closed-cell structure, stable gas insulation layer, and good moisture resistance and adhesion. In building and HVAC systems, rubber and plastic are insulation materials known for their stability and practicality, and their thermal conductivity maintains long-term reliability under reasonable operating conditions.