What are the effects of Irgafos 168 on the electrical properties of polymers?

As a trusted supplier of Irgafos 168, I've witnessed firsthand the growing interest in understanding its impact on the electrical properties of polymers. In this blog, we'll delve into the science behind Irgafos 168 and how it affects the electrical performance of polymers.

Understanding Irgafos 168

Irgafos 168, also known as tris(2,4 - di - tert - butylphenyl) phosphite, is a well - known processing stabilizer for polymers. It belongs to the class of organophosphite antioxidants. Its primary function is to protect polymers from thermo - oxidative degradation during high - temperature processing. When polymers are subjected to high temperatures during extrusion, injection molding, or other manufacturing processes, they can undergo oxidation, which leads to chain scission, cross - linking, and a decline in their physical and chemical properties. Irgafos 168 works by decomposing hydroperoxides formed during the oxidation process, thereby preventing the propagation of the oxidation reaction [1].

Chemical Structure and Reactivity

The chemical structure of Irgafos 168 is characterized by three bulky 2,4 - di - tert - butylphenyl groups attached to a central phosphorus atom. These bulky groups provide steric hindrance, which enhances the stability of the molecule. The phosphorus atom in Irgafos 168 has a relatively low oxidation state, and it can react with hydroperoxides (ROOH) according to the following reaction:

[P(OR)_3+ROOH\rightarrow P(OR)_2OOR + ROH]

This reaction effectively breaks the hydroperoxide into more stable products, thus interrupting the oxidative chain reaction.

Impact on Electrical Conductivity

Influence on Intrinsic Conductivity

For most polymers, which are typically insulators, the addition of Irgafos 168 generally has a negligible direct impact on their intrinsic electrical conductivity. Polymers like polyethylene, polypropylene, and polystyrene have very low free - charge carrier concentrations, and the presence of Irgafos 168 does not introduce significant amounts of mobile charge carriers.

However, in some cases, if the polymer contains impurities or has a small amount of charge - transfer complexes, Irgafos 168 can indirectly affect the conductivity. By preventing the oxidation of the polymer matrix, it maintains the integrity of the polymer structure. Oxidation can lead to the formation of polar groups and structural defects, which may act as traps for charge carriers or disrupt the ordered arrangement of polymer chains that can affect the hopping or tunneling of charge carriers.

Surface Conductivity

The surface of a polymer can be more susceptible to environmental factors and oxidation. Irgafos 168 can help maintain the surface properties of the polymer. Oxidation on the polymer surface can lead to the formation of a thin layer of oxidized products, which may have different electrical properties compared to the bulk polymer. This oxidized layer can increase surface resistivity or cause non - uniform surface conductivity. By preventing oxidation, Irgafos 168 helps to keep the surface of the polymer in a more stable state, ensuring consistent surface electrical properties.

Dielectric Properties

Dielectric Constant

The dielectric constant ((\epsilon_r)) of a polymer is related to its ability to store electrical energy in an electric field. Irgafos 168 can influence the dielectric constant of polymers in several ways. First, its presence can affect the mobility of polymer chains. Oxidation can cause cross - linking or chain scission, which changes the flexibility and mobility of polymer chains. Since the dielectric constant is related to the orientation of polar groups and the mobility of polymer chains, maintaining the polymer's original structure through the use of Irgafos 168 can help keep the dielectric constant within a stable range.

Second, Irgafos 168 itself has a certain dipole moment due to the polar P - O bonds in its structure. When it is dispersed in the polymer matrix, it can contribute to the overall polarization of the material. However, since it is usually added in relatively small amounts (typically in the range of 0.1 - 1% by weight), its direct contribution to the dielectric constant is relatively small compared to the polymer matrix.

Dielectric Loss

Dielectric loss is a measure of the energy dissipated as heat when a polymer is subjected to an alternating electric field. Oxidation of polymers can increase dielectric loss. Oxidized products often contain polar groups such as carbonyl groups, which can undergo dipole relaxation in an alternating electric field, leading to energy dissipation. By preventing oxidation, Irgafos 168 helps to reduce the formation of these polar oxidation products, thereby lowering the dielectric loss of the polymer.

Comparison with Other Antioxidants

Irganox B215

Irganox B215 is a blend of Irganox 1010 (a hindered phenolic antioxidant) and Irgafos 168. While Irgafos 168 is mainly responsible for processing stabilization, Irganox 1010 provides long - term thermal stability. In terms of electrical properties, the combination in Irganox B215 can have a synergistic effect. Irgafos 168 protects the polymer during high - temperature processing, and Irganox 1010 continues to prevent oxidation during long - term use. This dual protection can lead to better - maintained electrical properties over the polymer's lifespan compared to using either antioxidant alone.

AT - 168

AT - 168 is a product similar to Irgafos 168. It has the same chemical structure and similar antioxidant performance. In terms of electrical properties, AT - 168 is expected to have similar effects on polymers as Irgafos 168. The choice between the two may depend on factors such as cost, availability, and specific application requirements.

Practical Applications

Electrical Insulation

In the field of electrical insulation, polymers are widely used to isolate electrical conductors. Maintaining stable electrical properties is crucial for the safe and efficient operation of electrical systems. Irgafos 168 can be added to polymers such as polyethylene and polypropylene used in cables and electrical connectors. By preventing oxidation during the manufacturing process and long - term use, it ensures that the dielectric properties and insulation resistance of the polymers remain stable, reducing the risk of electrical breakdown.

Electronic Packaging

Polymers are also used in electronic packaging to protect electronic components from environmental factors. The electrical properties of these polymers need to be carefully controlled to avoid interference with the operation of electronic devices. Irgafos 168 can help maintain the electrical integrity of the packaging materials, ensuring that they do not introduce unwanted electrical noise or affect the performance of the enclosed electronic components.

Conclusion

Irgafos 168 plays a significant role in maintaining the electrical properties of polymers. By preventing thermo - oxidative degradation during processing and long - term use, it helps to keep the electrical conductivity, dielectric constant, and dielectric loss of polymers within stable ranges. Whether you are in the electrical insulation industry or electronic packaging, Irgafos 168 can be a valuable additive to improve the performance and reliability of your polymer products.

If you are interested in learning more about Irgafos 168 or are considering purchasing it for your polymer applications, we invite you to contact us for procurement and further discussion. Our team of experts is ready to provide you with detailed technical support and help you find the best solution for your specific needs.

References

[1] Zweifel, H., Kirschning, R., & Pospisil, J. (2001). Plastics Additives Handbook. Hanser Publishers.