Nylon is an important engineering plastic with excellent mechanical properties, heat resistance, oil resistance, corrosion resistance and relatively low friction coefficient. Due to these characteristics, nylon is widely used in automobiles, aerospace, electronics and electrical, machinery and other fields. However, nylon is easy to burn in high temperature environments, which has caused certain limitations on its application. Therefore, the research on flame retardant nylon has important practical significance.

1.2?The Need and Importance of Flame Retardant Nylon

With the advancement of science and technology and the development of industrialization, the application field of nylon is constantly expanding. At the same time, the fire accidents caused by it are also on the rise. Especially in high temperature environments, the flammability of nylon poses a serious threat to its application safety. Therefore, the research and development of flame retardant nylon has important practical significance and social value.

1.3?The Challenges and Importance of Flame Retardant Selection in High Temperature Environments

In high temperature environments, the requirements for flame retardants are more stringent. Since the thermoforming temperature of nylon is relatively high, the flame retardant selected should be able to withstandIt can withstand temperatures above 270°C without decomposing. Therefore, choosing the right flame retardant is a key issue in the research of flame-retardant nylon under high temperature environment. At the same time, a single flame retardant often cannot meet actual needs, and the synergistic effect of multiple flame retardants and their optimal configuration have become the focus of research.

At present, the research on flame-retardant nylon in high temperature environment is still in the stage of continuous deepening and improvement. Although some achievements have been made, there are still many challenges and problems to be solved. Therefore, the research on flame-retardant nylon in high temperature environment has important theoretical significance and practical application value.

two,?Basic concepts and types of flame retardants

2.1?What is flame retardant and how it works

Flame retardant is an additive that can inhibit the combustion of materials. During the combustion process, flame retardants can block flames, reduce flammability, reduce heat conduction, etc., making it difficult for materials to burn or slowing down the burning speed. The working principle of flame retardants is mainly based on the following points:

Release of non-flammable gas：Some flame retardants can decompose and produce non-combustible gases when heated. These gases can dilute the combustible gases and reduce the oxygen concentration in the combustion zone, thereby achieving a flame retardant effect.

Endothermic effect：Some flame retardants absorb a lot of heat during the combustion process, lowering the temperature of the material surface and slowing down the burning speed.

Heat insulation and oxygen isolation：Flame retardants can form a protective layer on the surface of the material, isolating the conduction of oxygen and heat, thereby slowing down combustion.

2.2?Characteristics and application range of different types of flame retardants

There are many types of flame retardants, each with its own unique characteristics and application range. The following are some common types of flame retardants:

Inorganic flame retardants：Inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide have high thermal stability, good temperature resistance, are not easy to decompose, and are relatively cheap. They mainly achieve flame retardant effects through heat absorption.

Organic halogen flame retardantsOrganic halogen flame retardants such as tetrabromophthalic anhydride and chlorinated paraffin have excellent flame retardant properties and have little effect on the mechanical properties of materials. However, these flame retardants are easy to decompose in high temperature environments and may produce harmful substances.

Organophosphorus flame retardants：Organophosphorus flame retardants such as phosphates and phosphites have good flame retardant effects and can effectively reduce smoke density. However, this type of flame retardant has a certain effect on the gloss of the material.

Nitrogen flame retardant：Nitrogen flame retardants such as melamine and urea mainly produce non-flammable gases to dilute oxygen and heat, thereby achieving flame retardant effects. This type of flame retardant has a certain effect on the color and processing properties of the material.

2.3?How to choose the right type of flame retardant for high temperature environments

In high temperature environment, materials are more likely to burn, so the requirements for flame retardants are higher. The following aspects need to be considered when choosing a suitable flame retardant:

Temperature resistance: Flame retardants used in high temperature environments should have good thermal stability and not be easy to decompose.

Compatibility: The flame retardant should have good compatibility with the material and should not be easily precipitated or migrated.

Synergy：The combined use of multiple flame retardants can play a synergistic role and improve the flame retardant effect.

Environmental protection: Priority should be given to low-toxic, low-smoke, biodegradable and environmentally friendly flame retardants.

three,?Selection principles of flame retardants in high temperature environments

3.1?Consider the thermal stability and temperature resistance of flame retardants

In high temperature environments, the thermal stability and temperature resistance of flame retardants are key factors in selection. Since the thermoforming temperature of nylon is relatively high, the flame retardant selected should be able to withstandHigh temperature above 270℃ without decomposition. For example, aluminum hydroxide flame retardant with low thermal decomposition temperature will suffer serious losses during processing and will produce more pores in the product. If the thermal decomposition temperature of the flame retardant is too high, it cannot be consistent with the decomposition temperature of nylon during combustion, which will cause the nylon to burn out and the flame retardant will not work quickly. Therefore, a flame retardant with a thermal decomposition temperature of 300-400℃ should be selected.

3.2?Compatibility Analysis of Flame Retardant and Nylon

The compatibility of flame retardants with nylon has an important influence on the flame retardant effect and material properties. Inappropriate flame retardants may lead to poor compatibility between flame retardants and nylon, affecting the processing performance and mechanical properties of the material. Therefore, when selecting flame retardants, their compatibility with nylon should be considered, and flame retardants with good compatibility with nylon and that can be evenly dispersed in the material should be selected as much as possible.

3.3?Study on the Addition Amount and Saturation Point of Flame Retardant

The amount of flame retardant added has an important influence on the flame retardant effect and material properties. Before reaching the saturation point, the flame retardant effect gradually increases with the increase in the amount of flame retardant added. However, when the amount added exceeds the saturation point, the flame retardant effect will no longer increase, but may lead to a loss of material properties. Therefore, when selecting a flame retardant, its optimal addition amount in nylon should be considered to obtain the best flame retardant effect and material properties. In addition, in order to achieve the optimal configuration of multiple flame retardants, the synergy between different flame retardants and how to reduce the dosage and loss of mechanical properties should be studied.

Four,?Advantages and methods of combined use of flame retardants

4.1?Comparative analysis of single flame retardant and combination of multiple flame retardants

In terms of the selection of flame retardants, there is a clear difference between a single flame retardant and a combination of multiple flame retardants. A single flame retardant often performs well in one aspect, but in actual applications, it is difficult for a single flame retardant to meet multiple needs in a complex environment. In contrast, a combination of multiple flame retardants can give full play to the advantages of various flame retardants, make up for each other's shortcomings, and work together to produce a better flame retardant effect.

4.2?Research progress on synergistic effect of multiple flame retardants

In recent years, the synergistic effect of multiple flame retardants has become a research hotspot. Through a reasonable combination of flame retardants, the flame retardant properties of nylon can be significantly improved, while reducing the use of a single flame retardant and reducing the impact on the environment. The synergistic mechanism between various flame retardants, the optimal combination ratio, and performance in high-temperature environments are all the focus and difficulties of current research.

4.3?How to achieve optimal configuration of multiple flame retardants

In order to give full play to the synergistic effect of multiple flame retardants, it is necessary to optimize their configuration. First, the performance characteristics and optimal use conditions of various flame retardants should be understood. Secondly, through experimental research and simulation calculations, the optimal combination ratio of various flame retardants should be found. In addition, factors such as the order of adding flame retardants, processing technology, and compatibility with nylon need to be considered to ensure that the final flame retardant nylon has good comprehensive performance.

Through the above methods, the optimal configuration of multiple flame retardants can be achieved, further improving the flame retardant properties of nylon while reducing the impact on the environment. This provides a strong guarantee for the safe application of nylon materials in high temperature environments, and has important practical significance and broad application prospects.

five,?Preparation technology and performance test of flame retardant nylon under high temperature environment

5.1?Analysis of the influence of preparation process on the properties of flame retardant nylon

The preparation process of flame-retardant nylon has a significant impact on its performance. A suitable preparation process can not only ensure the uniform dispersion of the flame retardant in the nylon matrix, but also ensure good compatibility between the flame retardant and the nylon material, thereby improving the flame retardant effect and the overall performance of the material. Unreasonable preparation processes may lead to the aggregation of flame retardants, reduce the flame retardant effect, and may have a negative impact on the mechanical properties of nylon.

5.2?Preparation method of flame retardant nylon samples with different flame retardant configurations

In order to achieve good flame retardant effect in high temperature environment, it is necessary to select appropriate flame retardant and optimize the configuration. When preparing flame retardant nylon samples, attention should be paid to the type, addition amount and compatibility of flame retardant with nylon. It is recommended to mix flame retardant with nylon by melt blending method and process it by twin screw extruder to ensure that the prepared flame retardant nylon sample has excellent performance.

5.3?Introduction to flame retardant performance testing and evaluation standards of flame retardant nylon

In order to evaluate the flame retardant properties of flame retardant nylon, appropriate test methods and evaluation standards should be used. According to international standardsISO 5658-2 and GB/T 2408 can use vertical burning test to evaluate the flame retardant properties of flame retardant nylon. The flame retardant properties of flame retardant nylon are evaluated by observing the burning time, burning height and other indicators of the sample during the burning process. In addition, attention should also be paid to the uniformity and standardization of the evaluation standards to ensure the reliability and comparability of the test results.

six,?Application cases and prospects of flame retardant nylon in high temperature environment

6.1?Overview of current applications of flame-retardant nylon in high temperature environments

Flame-retardant nylon in high temperature environments has been widely used in many fields due to its excellent heat resistance, flame retardant properties and mechanical properties. These include but are not limited to: aerospace, automotive industry, petrochemical industry, electronic appliances and barbecue utensils. In these fields, flame-retardant nylon has won an important position due to its high temperature stability, low shrinkage and good processing properties.

6.2?Typical application case analysis and effect evaluation

In the automotive industry, flame-retardant nylon is widely used in engine parts, wire sheaths and connectors. Because it can maintain stable performance in high temperature environments, it effectively prevents fires and improves the safety of automobiles. In the aerospace field, flame-retardant nylon is used to manufacture aircraft internal parts. Its excellent heat resistance and lightness reduce the weight of the aircraft and also improve flight safety.

6.3?Forecast of development trend and challenges of flame retardant nylon in high temperature environment

With the development of science and technology and the acceleration of industrialization, the application scenarios in high temperature environments will become more extensive, and the demand for flame-retardant nylon will further increase. In the future, the development of flame-retardant nylon will tend to be higher performance, lower cost and more environmentally friendly. At the same time, how to improve the long-term durability of flame-retardant nylon, reduce production costs and develop new environmentally friendly flame retardants will be the main challenges facing flame-retardant nylon. Only by continuous improvement and innovation can we meet the ever-changing market and needs.