What Are The Thermal Properties Of Polymer Materials

August 19, 2024

What Are The Thermal Properties Of Polymer Materials?

1. Coefficient of linear thermal expansion

The coefficient of linear thermal expansion is the percentage change in length of a material for every 1°C change in temperature. The average coefficient of linear expansion indicates the linear expansion characteristics of a material in a certain temperature range.

The average coefficient of linear expansion, α, is calculated according to the following formula:

Where Δl is the arithmetic mean value of the length change of the specimen during expansion or contraction, mm; l is the length of the specimen at room temperature, mm; Δt is the temperature difference of the specimen in the high and low temperature thermostat, ℃.

Test standard: GB/T1036-2008 Determination of coefficient of linear expansion of plastics from -30 ℃ to 30 ℃ Quartz expansion meter method.

2. Thermal conductivity

Thermal conductivity (thermal conductivity) refers to the rate of heat conduction through a unit area under stable heat transfer conditions, perpendicular to the unit temperature gradient in the direction of the unit area, also known as the coefficient of thermal conductivity.

Thermal conductivity λ is calculated by the following formula

Where Q is the thermal conductivity of the specimen at constant time, J; S is the thickness of the specimen, m; A is the effective heat transfer area of the specimen, m2; ΔZ is the time interval of the measurement, s; Δt is the average temperature difference between the hot and cold plate, K.

Test standard: GB/T 3399-1982 Thermal conductivity test method for plastics Thermal plate method.

3. Specific heat capacity

Specific heat capacity (specific heat capacity) is in the specified conditions, the unit mass of polymer temperature increased by 1 ℃ heat required, called the specific heat capacity of the material.

Specific heat capacity is calculated according to the following formula:

Where ΔQ is the heat absorbed by the specimen, J; m is the mass of the specimen, kg; Δt is the difference in temperature before and after the specimen absorbs the heat, K.

Test standard: GB/T 3140-2005 Test Method for Average Specific Heat Capacity of Fiber Reinforced Plastics

4. Glass transition temperature

Amorphous or semi-crystalline polymers, from the viscous flow state or high elastic state to the glass state of the transition is called the glass transition. The glass transition occurs within a narrow temperature range, the temperature at its approximate midpoint is called the glass transition temperature (glass transition temperature).

Glass transition temperature, commonly used expansion meter method or temperature - deformation curve method; can also be used for differential thermal analysis, such as TDA, DSC, TMA determination.

Test standard GB/T 11998-89 Plastic glass transition temperature determination method Thermal instrumentation analysis method.

5. Mechanical properties at low temperature

Mechanical properties at low temperature (mechanical properties at low temperature) represents the mechanical behavior of materials at low temperature. Commonly used test methods are low-temperature folding, stamping and elongation and other methods.

Brittle temperature (brittle temperature): a measure of low temperature mechanical behavior of polymers. With a certain energy most of the hammer impact specimen, when the specimen crack probability of 50% of the temperature is called brittle temperature (℃).

Test standard: GB/T5470-2008 plastic impact embrittlement temperature test method.

6. Marten's heat resistance

Marten's lest (Marten's lest) refers to the heating furnace, so that the specimen is subjected to a certain bending stress, and at a certain rate of temperature, the specimen is heated at the free end of the free end of the amount of deflection of the temperature (℃).

Test standard: GB/T 1035-1970 Plastic heat resistance (Martin) test method

7. Vicat softening point

Under the condition of equal speed heating, a flat thimble with a specified load and a cross-sectional area of l mm2 is placed vertically on the specimen. When the flat thimble piercing the specimen l mm depth of the temperature, that is, the material specimens measured by the Vickers softening temperature (℃).

Test standard: GB/T 1633-2000 Determination of Vicat Softening Temperature (VST) of Thermoplastics

8. thermal decomposition temperature

Thermal decomposition temperature (thermal decomposition temperature) refers to the temperature (℃) at which the macromolecules of the material are cracked under the heat condition. It can be determined by heat loss method, differential pressure method or decomposition gas detection method (TA).

9. flame resistance

Flame resistance refers to the ability of a material to resist combustion when in contact with a flame or to prevent continued combustion when removed from a flame.

Test standard:

GB/T2406-1993 Test Method for Combustion Performance of Plastics Oxygen Index Method

GB/T 2407-1980 Test method for combustion performance of plastics Fiery rod method

GB/T 2408-1996 Test Method for Combustion Performance of Plastics: Horizontal Method and Flaming Method

GB/T 4610-1984 Measurement of ignition temperature of plastic combustion performance test method

GB/T 8323-1987 Test method for burning performance of plastics Smoke density method

GB/T 9638-1988 Measurement of combustion soot of plastics Weighing method

Author:

Ms. Tina

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