ABS Glass Transition Temperature | The Complete Guide

ABS Glass Transition Temperature

Glass transition temperature, also known as Tg, is a critical temperature in the behavior of amorphous polymers. It is the temperature at which the polymer transitions from a hard and brittle state to a more rubbery and flexible state, much like the behavior of glass as it is heated.

ABS glass transition temp is 105°C (221°f).

That means, Below the glass transition temperature, the plastic appears hard and has a glassy texture, while above this critical temperature, it exhibits more flexibility and resembles rubber.

Before diving deep into the concept of ABS plastic Tg, I will clarify how the Tg of plastic material is calculated.

What is Glass Transition Temperature?

Glass transition temperature (Tg) refers to the temperature at which a material shifts from a stiff and solid glassy state to a more flexible and rubbery state due to the gradual rise in molecular mobility.

As the temperature increases above Tg, the molecular chains in the material gain the ability to move more freely and demonstrate a viscous flow. On the other hand, below Tg, the material becomes fragile and displays elastic behavior.

How ABS Tg is Calculated?

ASTM E1356 is the prevailing method for determining the glass transition temperature of plastics, let alone ABS. The approach employs differential thermal analysis or differential scanning calorimetry to evaluate the Tg of materials.

However, the techniques are only suitable for amorphous materials and crystalline substances with stable partial amorphous areas that do not undergo decomposition in the glass transition region.

In both methods, DTA and DSC, thermal input triggers peaks that correspond to endothermic and exothermic transitions, indicating phase changes. DTA works by measuring the difference in temperature or time between the sample and reference materials while observing the changes in temperature of the sample in a particular atmosphere.

Conversely, DSC measures the disparity in heat flow to a sample and reference material while monitoring the temperature changes programmed in a specific atmosphere.

In addition to DTA and DSC, other techniques can determine the glass transition temperature of ABS plastic, including:

  • Thermomechanical analysis,
  • Thermal expansion measurement,
  • Micro-heat transfer measurement,
  • Heat capacity
  • Isothermal compressibility,
  • Specific heat measurements.

Interesting Read – ABS Melting Point, Properties, Applications, Advantages & Disadvantages

Factors Affecting ABS Glass Transition Temperature 

There are several factors affecting ABS Tg; however, the 3 most relevant factors are mentioned below.

Polymer Composition

The composition of ABS, which is a copolymer of acrylonitrile, butadiene, and styrene, can significantly impact its Tg. The ratio of these monomers in the polymer chain can influence the packing and mobility of polymer chains; hence, its Tg. Additives, fillers, or other polymers in the ABS matrix can also affect its Tg.

Processing Conditions

The processing conditions used to manufacture ABS can significantly impact its Tg. For example, the cooling rate during manufacturing can influence the polymer chain packing and mobility, affecting Tg. Other factors, such as the annealing temperature, the molecular weight of the polymer, and the degree of cross-linking, can also affect Tg.

Environmental Factors

Environmental conditions, such as humidity and temperature, can impact the Tg of ABS. High humidity levels can cause plasticizers to leach out of the polymer, affecting the packing and mobility of the polymer chains and, in turn, its Tg. Additionally, exposure to high temperatures can cause thermal degradation, which can lower Tg.


ABS glass transition temperature is a critical parameter that determines the mechanical behavior and applications of ABS. Measuring Tg is important in the manufacturing and design of ABS products.

ABS’s versatility and excellent mechanical properties make it a popular choice for various applications in different industries, such as automotive, electronics, toys, sports equipment, and medical.

Leave a Comment