The Secret Weapon of High Performance Polymers: How Complex Antioxidants Enhance their Antioxidant Capacity

admin 3月 15th, 2025 News

The Secret Weapon of High-Performance Polymers: How Complex Antioxidants Enhance their Antioxidant Capacity

Introduction: Why do high-performance polymers need “secret weapons”?

On the stage of materials science, high-performance polymers are undoubtedly a brilliant star. From aerospace to medical devices, from the automotive industry to electronics, they are everywhere. However, these “star materials” are not inherently perfect – the oxidation reaction is like an invisible destroyer, quietly eroding their performance and lifespan. This oxidation process will not only lead to deterioration in mechanical properties and deterioration in appearance, but may also cause safety issues. Therefore, scientists have been looking for a “secret weapon” that can effectively slow down the oxidation process, and composite antioxidants are the leader in this field.

So, what are compound antioxidants? How does it play a role in high-performance polymers? This article will deeply explore the composition, mechanism of action and its impact on polymer performance of composite antioxidants, and combine practical application cases and domestic and foreign literature data to reveal its importance in modern industry. We will also present key parameters in table form to help readers more intuitively understand the advantages and limitations of composite antioxidants. Next, please follow us to explore this world full of chemical mysteries!

Basic concepts and classifications of composite antioxidants

What are compound antioxidants?

Composite antioxidant is a mixture composed of a synergistic effect of multiple single antioxidants, designed to enhance the overall antioxidant properties of the polymer by optimizing the formulation design. Simply put, it is like a “multifunctional team” where each member (i.e., a single antioxidant) has his own strengths, but it can only work well when they work together.

Depending on the function, compound antioxidants can be divided into the following categories:

Main antioxidant
The main antioxidant is the core member of the composite system and is mainly responsible for capturing free radicals to prevent the occurrence of chain oxidation reactions. Common primary antioxidants include phenolic compounds (such as BHT, hindered phenols) and amine compounds (such as dianiline). They are characterized by efficiency and stability, but may be limited by environmental factors when used alone.
Auxiliary antioxidants
Auxiliary antioxidants play a role of “logistical support” and are often used to break down peroxides or repair molecular structures damaged by oxidation. Thioesters and phosphites are typical representatives, which can significantly reduce the aging rate of polymers.
Metal ion passivator
Under certain conditions, trace metal ions catalyze oxidation reactions, resulting in accelerated degradation of the polymer. to this end,Metal ion passivating agents (such as ethylenediaminetetrasalt) are often added to the composite antioxidants to inhibit this adverse effect.
Ultraviolet absorber
UV light is one of the important causes of luminescent oxidation reactions, and UV absorbers (such as benzotriazoles) can protect the polymer from further damage by shielding UV light.

Synergy Effects of Complex Antioxidants

The key reason why complex antioxidants are better than single antioxidants is their unique synergistic effects. For example, the primary antioxidant can quickly capture free radicals, while the secondary antioxidant can promptly remove by-products; the metal ion passivator ensures that the entire system is not affected by external interference. This multi-pronged approach allows composite antioxidants to maintain polymer stability for longer periods of time.

To illustrate this better, we can use a metaphor: If polymers are compared to a ship sailing in the sea, then the oxidation reaction is a reef hidden underwater. Single antioxidants may repair certain local damage, but composite antioxidants can fully reinforce the hull, making it more robust and durable.

Mechanism of action of composite antioxidants

The essence of oxidation reaction

To understand the mechanism of action of composite antioxidants, we must first understand the basic principles of oxidation reaction. The oxidation process of polymers is usually divided into three stages: initiation, propagation and termination.

Initiation phase
At this stage, weak bonds in polymer molecules (such as C-H bonds) are attacked by heat, light or oxygen to form free radicals. These free radicals are highly reactive intermediates that lay the foundation for subsequent reactions.
Propagation stage
Free radicals combine with oxygen to form peroxy radicals, which then react with other polymer molecules to produce more radicals. This chain reaction continues to expand like a snowball, eventually causing the polymer molecules to break or crosslink.
Termination Phase
When two radicals meet, they bind to each other to form stable molecules, thus ending the oxidation reaction. However, in practical cases, the probability of such natural termination is extremely low, so human intervention is required.

How to intervene in composite antioxidants?

Compound antioxidants interrupt the above oxidation process in the following ways:

Capture free radicals
The active functional groups (such as phenolic hydroxyl groups) in the main antioxidant can react with free radicals to convert them into relatively stablemolecule. For example, hindered phenolic antioxidants release hydrogen atoms, which bind to free radicals to form alcohol compounds.
Decompose peroxide
Peroxides are harmful by-products produced during oxidation and may lead to further degradation of the polymer. Auxiliary antioxidants (such as phosphites) decompose peroxides into harmless substances through reduction reactions.
Inhibiting metal catalysis
Trace metal ions (such as iron and copper) often act as catalysts for oxidation reactions. Metal ion passivators effectively prevent their catalytic behavior by forming complexes with these ions.
Shield UV rays
UV absorbers can absorb high-energy ultraviolet light and convert it into heat energy to emit it, thereby avoiding the occurrence of photooxidation reactions.

The following is a comparison table of the mechanisms of several common composite antioxidants:

Category	Main Ingredients	Function Description	Applicable scenarios
Main antioxidant	Stealed Phenol	Catch free radicals and terminate chain reaction	Engineering plastics used in high temperature environments
Auxiliary Antioxidants	Phostrite	Decompose peroxides and reduce by-products	Transparent polycarbonate for medical devices
Metal ion passivator	Ethylene diamine tetrasalt	Passification of metal ions to prevent catalytic oxidation	Food Packaging Film
Ultraviolet absorber	Benzotriazole	Absorb UV rays and reduce photooxidation	PVC products for outdoor use

The influence of composite antioxidants on the performance of high-performance polymers

Improving heat resistance and service life

The introduction of composite antioxidants greatly enhances the heat resistance and service life of high-performance polymers. Taking polyamide (PA) as an example, untreated PA is prone to thermal oxidation and degradation at high temperatures, resulting in a significant decline in mechanical properties. However, after adding composite antioxidants, their thermal stability can be improved by more than 30%, and at the same time, useExtend lifespan to twice the original one.

Specific manifestations are:

The change in the melt index (MFI) decreases
The tensile strength and elongation at break remain high
Surface gloss is maintained

Improving Processing Performance

In the polymer processing process, composite antioxidants can also play a role in lubrication and stability. For example, during injection molding, polypropylene (PP) containing the appropriate proportion of composite antioxidants exhibits lower shear stress and higher fluidity, thereby reducing mold wear and improving productivity.

In addition, composite antioxidants can also reduce melt viscosity and make the extrusion process smoother. This is especially important for the production of large and complex components.

Enhanced environmental protection characteristics

As the increasing global attention to environmental protection, the development of green and efficient composite antioxidants has become an industry trend. The new bio-based antioxidants not only have good antioxidant properties, but are also completely degradable and will not cause pollution to the environment. This provides more possibilities for high-performance polymers in the field of sustainable development.

The following is a comparison table of performance of several typical high-performance polymers before and after the addition of composite antioxidants:

Polymer Type	parameters	Pre-add value	Add value	Percentage increase (%)
Polyether etherketone (PEEK)	Oxidation induction time (min)	12	28	+133
Polyphenylene sulfide (PPS)	Thermal deformation temperature (°C)	260	300	+15
Polycarbonate (PC)	Spreadability (%)	85	92	+8

Analysis of domestic and foreign research progress and application case

Summary of domestic and foreign literature

In recent years, many breakthroughs have been made in the research on compound antioxidants. For example, a study published by American scholar Smith et al. in the journal Polymer Degradation and Stability showed that by optimizing the ratio of primary antioxidants to auxiliary antioxidants, nitric acid can be achieved by optimizing the ratio of primary antioxidants to auxiliary antioxidants.Good regulation of Long 66’s antioxidant properties. The experimental results show that when the mass ratio of the main antioxidant and the auxiliary antioxidant is 3:1, the tensile strength of nylon 66 can still maintain more than 85% of the initial value after continuous aging at 150°C for 100 hours.

In China, Professor Zhang’s team from Tsinghua University proposed a method for preparing composite antioxidants based on nanotechnology. They loaded traditional antioxidants on the surface of silica nanoparticles, successfully solving the problem of easy migration of traditional antioxidants, while greatly improving their dispersion uniformity and long-term effectiveness.

Practical Application Cases

Case 1: Automobile Engine Cover

A well-known automaker uses glass fiber reinforced polypropylene material containing composite antioxidants in the engine cover of its new model. Tests show that the material can maintain excellent dimensional stability and impact resistance under extreme operating conditions (such as long-term exposure to high temperatures of 120°C), far exceeding the performance of traditional materials.

Case 2: Medical device shell

A medical device company has selected polycarbonate with composite antioxidants as the shell material for its high-end CT scanners. Thanks to the excellent performance of the composite antioxidant, the case not only has excellent optical properties, but also has no obvious yellowing during the five-year service life, winning wide praise from customers.

Case 3: Outdoor Billboard

A certain advertising company used composite antioxidant-modified PVC material containing ultraviolet absorbers when making large outdoor billboards. Even after three years of wind and sun exposure, the color of the billboard is still as bright as before, fully demonstrating the strong strength of composite antioxidants in resisting light oxidation.

Conclusion and Outlook

Through the detailed discussion in this article, we can clearly see the huge role of composite antioxidants in improving the antioxidant capacity of high-performance polymers. Whether it is theoretical research or practical application, its excellent results and wide applicability have been fully verified.

However, the development path of composite antioxidants has not stopped here. In the future, with the continuous progress of emerging fields such as nanotechnology and smart materials, composite antioxidants are expected to show more novel functions. For example, developing composite antioxidants with self-healing capabilities may revolutionize our perception of polymer aging.

In short, composite antioxidants are not only the “secret weapon” of high-performance polymers, but also an important driving force for the development of materials science. Let us look forward to more exciting discoveries in this field together!