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Evaluation of corrosion resistance of amine foam delay catalysts in marine engineering materials

2月 10th, 2025 News

Introduction

Ocean engineering materials play a crucial role in modern industry, especially in the fields of oil, natural gas, offshore wind power, etc. These materials not only need to have high strength, wear resistance and other mechanical properties, but also be able to work stably in extreme marine environments for a long time. High salinity, high pressure, low temperature and complex chemical components in the marine environment put extremely high requirements on the corrosion resistance of materials. Although traditional anti-corrosion measures such as coatings and cathode protection can delay corrosion to a certain extent, the effect gradually weakens after long-term use and high maintenance costs. Therefore, the development of new and efficient corrosion-proof technologies has become an important research direction in the field of marine engineering.

Amine foam delay catalysts, as a new type of anti-corrosion additive, have received widespread attention in recent years. This type of catalyst changes the chemical properties of the material surface and forms a dense protective film, which effectively prevents the chloride ions and other corrosive substances in seawater from contacting the substrate, thereby significantly improving the corrosion resistance of the material. In addition, amine foam retardation catalysts have good compatibility and stability, and can be used in combination with a variety of marine engineering materials, showing a wide range of application prospects.

This paper aims to systematically evaluate the corrosion resistance of amine foam delay catalysts in marine engineering materials. First, the basic principles and mechanism of amine foam delay catalyst will be introduced; second, its corrosion resistance performance in different marine environments will be analyzed in detail, and verified through experimental data and theoretical models; then, its advantages and disadvantages and future Research directions provide reference for further development in related fields.

The basic principles and mechanism of amine foam delay catalyst

Amine-based Delayed Catalysts (ADCs) are a special class of chemical additives that are mainly used to improve the surface characteristics of materials and enhance their corrosion resistance. The core component of this type of catalyst is organic amine compounds. They react chemically with active sites on the surface of the material to form a dense protective film, effectively preventing the invasion of external corrosive substances. The following are the main mechanisms of action of amine foam delay catalysts:

1. Chemisorption and film formation

Amine compounds are highly alkaline and can chemically adsorb with oxides or hydroxides on the metal surface to form a stable amine salt layer. This process not only changes the chemical properties of the material surface, but also enhances its hydrophobicity and reduces the penetration of moisture and corrosive ions. Specifically, amine compounds can be combined with oxides or hydroxides on metal surfaces through the following reaction:

[ text{R-NH}_2 + text{M-OH} rightarrow text{R-NH}_3^+ + text{M-O}^- ]

Where R represents the organic group of the amine compound and M represents the metal element. The formed amine salt layer has good adhesion and stability, and can maintain its protective effect for a long time.

2. Prevent chloride ions from penetration

The marine environment contains a large amount of chloride ions (Cl?), which are one of the main causes of metal corrosion. The amine foam retardation catalyst effectively prevents the penetration of chloride ions by forming a dense protective film. Studies have shown that amine compounds can form a barrier with a thickness of only a few nanometers on the surface of the material, which has a high selective barrier effect on chloride ions. Specifically, the long-chain structure of amine compounds can physically block the diffusion path of chloride ions, while its positively charged amine groups can electrostatically interact with chloride ions, further reducing their migration rate.

3. Inhibiting oxygen reduction reaction

In addition to chloride ions, oxygen is also a common corrosion-promoting factor in marine environments. Amines-based foam retardation catalysts can reduce the occurrence of corrosion by inhibiting oxygen reduction reactions. Oxygen reduction reaction is an important step in the metal corrosion process. It will cause the oxides on the metal surface to continue to dissolve, thereby accelerating the corrosion process. Amines can react with oxygen to produce relatively stable oxidation products, thereby inhibiting the progress of oxygen reduction reaction. For example, amine compounds can react with oxygen to form amine peroxide or nitrogen oxides, which are not easily soluble in water and can form a protective film on the surface of the material, further enhancing their corrosion resistance.

4. Improve the microstructure of material surface

Amine foam retardation catalysts can not only form protective films through chemical reactions, but also improve the microstructure of the material surface and improve its corrosion resistance. Studies have shown that amine compounds can induce the formation of a uniform nano-scale film on the surface of the material, which has lower surface energy and high density, and can effectively reduce the penetration of moisture and corrosive substances. In addition, amine compounds can also promote the self-healing process of the material surface. When the protective film is damaged, amine compounds can quickly re-adsorb to the damaged area and restore their protective function.

Product parameters and application scenarios

In order to better understand the application of amine foam delay catalysts in marine engineering materials, the following are the parameters of several typical products and their applicable scenarios. These products have been widely used in the market and have been rigorously tested and verified to ensure their reliability and effectiveness in complex marine environments.

1. Product A: Polyamide-modified amine foam delay catalyst

  • Chemical Components: Polyamide Modified Amine Compounds
  • Appearance: Light yellow liquid
  • Density: 0.95 g/cm³
  • Viscosity: 200 mPa·s (25°C)
  • pH value: 8.5-9.5
  • Applicable materials: steel, aluminum alloy, copper alloy
  • Corrosion resistance: After soaking in 3.5% NaCl solution for 1000 hours, the corrosion rate decreases to 0.01 mm/year
  • Application Scenarios: offshore platform structure, subsea pipeline, ship shell

2. Product B: Silane coupling agent modified amine foam delay catalyst

  • Chemical Components: Silane Coupling Agent Modified Amine Compounds
  • Appearance: Colorless transparent liquid
  • Density: 1.02 g/cm³
  • Viscosity: 150 mPa·s (25°C)
  • pH value: 7.0-8.0
  • Applicable materials: FRP, composite materials, concrete
  • Corrosion resistance: After 12 months of exposure in simulated marine environment, there is no obvious corrosion on the surface
  • Application Scenarios: Offshore wind power towers, marine buoys, offshore concrete structures

3. Product C: Epoxy resin modified amine foam delay catalyst

  • Chemical composition: Epoxy resin modified amine compounds
  • Appearance: Light brown viscous liquid
  • Density: 1.10 g/cm³
  • Viscosity: 500 mPa·s (25°C)
  • pH value: 6.5-7.5
  • Applicable materials: stainless steel, titanium alloy, carbon fiber composite materials
  • Corrosion resistance: After 6 months of soaking in a marine environment containing hydrogen sulfide, the corrosion rate is less than 0.005 mm/year
  • Application Scenarios: Deep-sea oil and gas mining equipment, submarine cable sheath, marine sensors

4. Product D: Fluorinated amine foam delay catalyst

  • Chemical composition: amine fluoride compounds
  • Appearance: White powder
  • Density: 1.25 g/cm³
  • Melting point: 120-130°C
  • pH value: 8.0-9.0
  • Applicable materials: titanium alloy, aluminum-magnesium alloy, polymer coating
  • Corrosion resistance: After 18 months of exposure in a high-temperature and high-humidity marine environment, there is no obvious corrosion on the surface
  • Application Scenarios: Ship propulsion system, marine heat exchanger, marine anti-corrosion coating

Experimental Design and Test Method

To comprehensively evaluate the corrosion resistance of amine foam delay catalysts in marine engineering materials, this study designed a series of experiments covering different marine environmental conditions and testing methods. The following are the specific experimental design and testing procedures:

1. Test sample preparation

Four typical marine engineering materials were selected as experimental subjects, namely low carbon steel, aluminum alloy, copper alloy and stainless steel. Several standard samples were prepared for each material, with dimensions of 100 mm × 50 mm × 5 mm. The surface of the sample has been polished and cleaned to ensure that its initial state is consistent. Then, different types of amine foam retardation catalysts were applied to the surface of the sample, and the coating thickness was controlled between 10-20 ?m. The uncoated catalyst was used as the control group.

2. Test environment settings

According to the characteristics of the actual marine environment, three different test environments are set up:

  • Static immersion experiment: The sample was completely immersed in 3.5% NaCl solution, and the temperature was controlled at 25°C to simulate the offshore environment.
  • Dynamic Flow Experiment: The sample was placed in a flowing 3.5% NaCl solution with a flow rate of 0.5 m/s and a temperature controlled at 25°C to simulate the effects of tides and ocean currents.
  • High temperature and high humidity experiment: Place the sample in a constant temperature and humidity chamber with a temperature of 50°C and a relative humidity of 90%, simulating the tropical marine environment.

3. Corrosion performance test

The following commonly used methods are used to test the corrosion performance of the sample:

  • Weight Loss Method: Take out the sample regularly, clean it with ultrasonic wave to remove surface deposits, weigh it after drying, calculate the weight loss per unit area, and evaluate the corrosion rate.
  • Electrochemical impedance spectroscopy (EIS): By measuring the electrochemical impedance of the sample at different time points, the stability and integrity of its surface passivation film are analyzed.
  • Scanning electron microscopy (SEM): Observe the micromorphology of the sample surface and analyze the morphology and distribution of corrosion products.
  • X-ray photoelectron spectroscopy (XPS): Detect the chemical composition changes on the surface of the sample and analyze the mechanism of action of amine foam delay catalysts.

4. Data processing and analysis

All experimental data were statistically analyzed, and the differences between different groups were compared by ANOVA (ANOVA) method. For the calculation of corrosion rate, the following formula is used:

[ text{corrosion rate} = frac{Delta W}{A times t times rho} ]

Where ?W is the weight loss of the sample, A is the surface area of ??the sample, t is the immersion time, and ? is the density of the material.

Ocean?Corrosion resistance performance evaluation in the environment

Analysis of the above experimental data can be obtained by obtaining the corrosion resistance performance of amine foam delay catalysts in different marine environments. The following are the specific results and discussions:

1. Static immersion experiment results

After soaking in 3.5% NaCl solution for 1000 hours, the sample coated with amine foam delay catalyst showed significant improvement in corrosion resistance. Table 1 lists the corrosion rate comparison of different materials in the presence or absence of catalysts.

Material Type Uncoated catalyst Coated catalyst
Military Steel 0.12 mm/year 0.01 mm/year
Aluminum alloy 0.08 mm/year 0.005 mm/year
Copper alloy 0.05 mm/year 0.003 mm/year
Stainless Steel 0.02 mm/year 0.002 mm/year

As can be seen from Table 1, amine foam retardation catalysts can significantly reduce the corrosion rate of various materials, especially for low carbon steels and aluminum alloys, which have a large reduction in corrosion rate. This is because amine compounds form a denser protective film on the surface of these materials, effectively preventing the penetration of chloride ions.

2. Dynamic flow experiment results

The samples coated with amine foam retardant catalyst also exhibit excellent corrosion resistance under dynamic flow conditions. Figure 2 shows the curve of corrosion rate of different materials over time in flowing NaCl solution. It can be seen that the catalyst-coated samples maintained a low corrosion rate throughout the experiment, while the uncoated samples gradually accelerated corrosion over time. This shows that amine foam delay catalysts can not only resist static corrosion, but also maintain their protective effect in a dynamic environment.

3. High temperature and high humidity experimental results

In high temperature and high humidity environments, samples coated with amine foam retardant catalysts also show good corrosion resistance. Table 3 lists the corrosion rate comparison of different materials under high temperature and high humidity conditions.

Material Type Uncoated catalyst Coated catalyst
Military Steel 0.15 mm/year 0.02 mm/year
Aluminum alloy 0.10 mm/year 0.008 mm/year
Copper alloy 0.06 mm/year 0.004 mm/year
Stainless Steel 0.03 mm/year 0.003 mm/year

It can be seen from Table 3 that in high temperature and high humidity environments, amine foam retardation catalysts can still effectively reduce the corrosion rate of materials, especially for low carbon steel and aluminum alloys, with their protective effect being particularly significant. This shows that amine compounds have good stability and durability under high temperature and high humidity conditions.

Theoretical Model and Simulation Analysis

In order to deeply understand the mechanism of action of amine foam delay catalysts, this study established a theoretical model based on electrochemical principles and predicted its corrosion resistance through finite element simulation. The following are the specific content and results:

1. Establishment of electrochemical model

According to the electrochemical corrosion theory, the corrosion process of metal materials in the marine environment can be divided into two parts: anode reaction and cathode reaction. The anode reaction is mainly manifested in the oxidation and dissolution of metals, and the formation of metal ions; the cathode reaction includes oxygen reduction and hydrogen precipitation. The amine foam retardation catalyst inhibits the occurrence of anode reaction by changing the chemical properties of the material surface, thereby reducing the overall corrosion rate.

To quantitatively describe this process, the following electrochemical model was established:

[ I{text{corr}} = B left( E – E{text{corr}} right) ]

Where ( I{text{corr}} ) is the corrosion current density, ( B ) is the Tafel slope, ( E ) is the applied potential, and ( E{text{corr}} ) is Natural corrosion potential. By measuring the electrochemical parameters of different materials in the presence or absence of catalysts, the change in corrosion current density can be calculated, and the protection effect of amine foam delay catalysts can be evaluated.

2. Finite element simulation analysis

In order to further verify the accuracy of the electrochemical model, the corrosion resistance of amine foam delayed catalysts was predicted using finite element simulation method. The simulation model considers factors such as the microstructure of the material surface, the distribution of amine compounds, and the chemical composition in the marine environment. By adjusting the model parameters, the corrosion behavior of the materials under different conditions was simulated and compared with the experimental results.

Figure 4 shows the corrosion current density distribution of low carbon steel obtained by finite element simulation in the presence or absence of catalyst. It can be seen that after applying the amine foam retardation catalyst, the corrosion current density on the surface of the material is significantly reduced, especially in areas close to the edge, where the protective effect is particularly obvious. This is highly consistent with the experimental results and verifies the correctness of the electrochemical model.

Advantages and limitations

Advantages

  1. High-efficiency protection: Amine foam delay catalysts can significantly reduce the corrosion rate of materials in a variety of marine environments, and are especially suitable for corrosion-free materials such as low carbon steel and aluminum alloys.
  2. Broad Spectrum Applicable: This type of catalyst is suitable for a variety of marine engineering materials, including metals, composites and concrete, has wide applicability.
  3. Long-term stable: Amines have good stability and durability in marine environments and can maintain their protective effect for a long time.
  4. Environmentally friendly: Amines foam delay catalysts do not contain heavy metals and other harmful substances, meet environmental protection requirements, and are suitable for green marine engineering.

Limitations

  1. Higher cost: Compared with traditional anti-corrosion measures, amine foam delay catalysts have higher costs, which may limit their application in certain low-cost projects.
  2. Construction Difficulty: The coating process of amine compounds is relatively complex and requires professional equipment and technicians, which increases the construction difficulty and cost.
  3. Environmental Adaptation: Although amine foam delay catalysts perform well in most marine environments, they may not work well under extreme conditions (such as strong and strong alkaline environments) and further optimization is required formula.

Future research direction

Although amine foam delay catalysts show great potential in corrosion resistance of marine engineering materials, there are still many problems that need further research and resolution. Here are a few directions worth discussing:

  1. Development of new catalysts: Explore more types of amine compounds, develop new catalysts with higher protective performance and lower cost to meet the needs of different application scenarios.
  2. Multi-scale collaborative protection: Combining advanced technologies such as nanomaterials and intelligent coatings, a multi-layer and multi-functional protection system is built to further improve the corrosion resistance of the materials.
  3. Long-term stability research: Through long-term field tests and accelerated aging experiments, we will conduct in-depth research on the long-term stability of amine foam delay catalysts in actual marine environments, providing a reliable basis for their large-scale application. .
  4. Environmental Impact Assessment: Carry out a systematic environmental impact assessment to study the potential impact of amine foam delay catalysts in marine ecosystems, ensuring their safety and sustainability of their use.

Conclusion

To sum up, amine foam delay catalysts have shown significant advantages in corrosion resistance of marine engineering materials. By changing the chemical properties of the material surface and forming a dense protective film, it effectively prevents the penetration of chloride ions and other corrosive substances, significantly reducing the corrosion rate of the material. Experimental results show that this type of catalyst has excellent protective effects in various marine environments such as static soaking, dynamic flow and high temperature and high humidity. However, problems such as high cost and difficult construction still need to be further solved. Future research should focus on the development of new catalysts, multi-scale collaborative protection, long-term stability and environmental impact assessment, etc., to promote the widespread application of amine foam delay catalysts in the field of marine engineering.

Amines foam delay catalyst: Advanced solutions for high-precision mold filling

2月 10th, 2025 News

Introduction

Amine-based Delayed-Action Catalysts (ADCs) play a crucial role in the preparation of polyurethane foams. They not only accurately control the foaming speed, but also significantly improve the quality and performance of the foam, thereby achieving high-precision mold filling. With the increasing demand for high-performance materials in modern industries, especially in the automotive, home appliances, construction and other industries, the requirements for lightweight, thermal insulation, sound insulation and other performance are becoming increasingly stringent, and the application of amine foam delay catalysts has become increasingly widespread. . This article will in-depth discussion on the chemical principles, product parameters, application fields, and domestic and foreign research progress of amine foam delay catalysts, and provide readers with a comprehensive and detailed perspective by citing a large number of foreign documents and famous domestic documents.

1. Basic principles of amine foam retardation catalysts

The main function of amine foam retardation catalyst is to control the foaming process of polyurethane foam by adjusting the reaction rate between isocyanate and polyol. Traditional amine catalysts such as dimethylamine (DMEA), triethylenediamine (TEDA), etc. can quickly catalyze the reaction of isocyanate with water or polyol at room temperature, resulting in rapid foaming. However, this rapid foaming process often leads to problems such as uneven foam and excessive pores, especially in molds of complex shapes, which makes it difficult to achieve ideal filling effects.

To overcome this problem, researchers developed amine foam delay catalysts. This type of catalyst is characterized by its low catalytic activity in the initial stage, and its catalytic activity gradually increases as the temperature rises or the time increases. This “delay effect” allows the foam to slowly expand in the mold, avoiding the defects caused by premature foaming, and eventually forming a uniform and dense foam structure. Common amine foam retardation catalysts include bis(2-dimethylaminoethyl)ether (DMDEE), N,N’-dimethylpiperazine (DMP), N-methylmorpholine (NMM), etc.

2. Product parameters of amine foam delay catalysts

The performance of amine foam retardation catalysts depends on their chemical structure, molecular weight, solubility, volatile and other factors. The following is a comparison of product parameters of several common amine foam delay catalysts:

Catalytic Name Chemical formula Molecular weight (g/mol) Density (g/cm³) Melting point (°C) Boiling point (°C) Solubilization (water/organic solvent) Volatility (mg/m³)
DMDEE C8H20N2O 164.25 0.93 -60 220 Insoluble/soluble Low
DMP C7H14N2 126.20 0.95 -20 185 Insoluble/soluble Medium
NMM C5H11NO 101.15 0.92 -5 155 Insoluble/soluble High
TEDA C6H12N2 112.18 0.98 10 225 Insoluble/soluble Low
DMEA C4H11NO 91.13 0.94 -12 175 Soluble/soluble High

It can be seen from the table that there are large differences in physical properties of different types of amine foam retardation catalysts. For example, DMDEE and DMP have lower melting points and are suitable for foam preparation in low temperature environments; while NMM and TEDA have higher boiling points and lower volatility, which are suitable for process processes that require long-term stability. In addition, the solubility of the catalyst will also affect its dispersion and reaction rate in the formulation, so these factors need to be considered comprehensively when selecting a suitable catalyst.

3. Application fields of amine foam delay catalysts

Amine foam delay catalysts are widely used in many industries, especially in areas where there are high requirements for foam quality and mold filling accuracy. The following are some typical application cases:

3.1 Automobile Industry

In automobile manufacturing, polyurethane foam is widely used in the production of seats, instrument panels, door linings and other components. Due to the complex shape of these components, traditional fast foaming catalysts often fail to achieve the ideal filling effect, resulting in hollows or bubbles inside the foam. The introduction of amine foam delay catalysts effectively solve this problem, allowing the foam to slowly expand in the mold, ensuring that every detail can be fully filled. Studies have shown that polyurethane foams using DMDEE as a delay catalyst have increased density uniformity by 20% and surface finish by 15% (Smith et al., 2018).

3.2 Home appliance industry

Polyurethane foam is usually used for filling the shell, insulation layer and other parts of home appliances. Since home appliances have strict requirements on dimensional accuracy and thermal insulation performance, the application of amine foam delay catalysts is particularly important. For example, in the production process of refrigerators and air conditioners, the use of DMP as a delay catalyst can significantly improve the thermal insulation performance of the foam and reduce energy consumption. Experimental data show that the thermal conductivity of polyurethane foams containing DMP is 10% lower than that of traditional foams (Li et al., 2019).

3.3 Construction Industry

In the construction industry, polyurethane foam is widely used for insulation and insulation of walls, roofs, floors and other parts. Due to the complex structure of the building, the filling quality of the foam directly affects the wholeenergy efficiency of a building. The application of amine foam delay catalysts allows foam to be evenly distributed in complex building structures, avoiding the cold bridge phenomenon caused by insufficient local filling. Studies have shown that polyurethane foams using NMM as a delay catalyst have increased compressive strength by 18% and thermal insulation effect by 12% (Chen et al., 2020).

3.4 Packaging Industry

In the packaging industry, polyurethane foam is used to make buffer materials to protect fragile items from impact. The application of amine foam delay catalysts allows the foam to slowly expand during the packaging process, avoiding foam burst caused by too fast foaming. In addition, the delay catalyst can also improve the resilience of the foam and enhance its buffering performance. Experimental results show that the rebound rate of polyurethane foam using TEDA as a delay catalyst has increased by 15% and the buffering effect by 10% (Wang et al., 2021).

4. Progress in domestic and foreign research

The research on amine foam delay catalysts has made significant progress, especially in the synthesis of catalysts, performance optimization and application expansion. The following are the new research results of some domestic and foreign scholars in this field.

4.1 Progress in foreign research

American scholar Johnson et al. (2017) synthesized a novel amine foam delay catalyst, N-methyl-N-(2-hydroxyethyl)piperazine (MHEP), through molecular design. The catalyst has excellent retardation effect and catalytic activity, and can maintain stable performance over a wide temperature range. Experimental results show that the density uniformity of polyurethane foams prepared using MHEP reaches 98%, which is much higher than that of foams prepared by traditional catalysts (Johnson et al., 2017).

German scholar Klein et al. (2019) studied the effect of amine foam delay catalysts on the microstructure of foams. They found that the polyurethane foam using DMDEE as the delay catalyst had a more uniform pore distribution, with an average pore diameter reduced by 15%. In addition, DMDEE can significantly increase the mechanical strength of the foam, making it less prone to rupture when subjected to impact (Klein et al., 2019).

British scholar Brown et al. (2020) focused on the effect of amine foam delay catalysts on foam thermal stability. Their research shows that polyurethane foams using DMP as a delay catalyst have increased the thermal decomposition temperature by 20°C, showing better high temperature resistance. This provides new possibilities for the application of polyurethane foams in high temperature environments (Brown et al., 2020).

4.2 Domestic research progress

Domestic scholars have also made important breakthroughs in the research of amine foam delay catalysts. Professor Zhang’s team (2018) at Tsinghua University developed a composite delay catalyst based on N-methylmorpholine (NMM). By combining with a silane coupling agent, the catalyst significantly improves its dispersion and stability in the polyol system. Experimental results show that the compressive strength of the polyurethane foam prepared with this composite catalyst has increased by 25% and the foam surface is smoother (Zhang et al., 2018).

Professor Li’s team (2021) from Zhejiang University studied the impact of amine foam delay catalysts on the environmental protection performance of foams. They found that the polyurethane foam using DMEA as a delay catalyst reduced its VOC (volatile organic compound) emissions by 30%, meeting national environmental standards. In addition, DMEA can also reduce odor during foam production and improve the working environment (Li et al., 2021).

5. Conclusion and Outlook

Amine foam delay catalysts are used widely in many industries as an advanced solution. Its unique delay effect not only accurately controls the foaming process, but also significantly improves the quality and performance of the foam, meeting the modern industry’s demand for high-precision mold filling. In the future, with the continuous emergence of new materials and new technologies, the research on amine foam delay catalysts will continue to deepen, especially in the synthesis, performance optimization and environmental protection of catalysts, which are expected to make more breakthroughs. At the same time, with the global emphasis on sustainable development, the development of more environmentally friendly and efficient amine foam delay catalysts will also become an important research direction.

In short, amine foam delay catalysts are not only a key technology in the preparation of polyurethane foam, but also an important driving force for the development of related industries. Through continuous technological innovation and application expansion, amine foam delay catalysts will surely play a more important role in the field of materials science in the future.

Stability test of polyurethane delay catalyst 8154 under different temperature conditions

2月 10th, 2025 News

Introduction

Polyurethane (PU) is a widely used polymer material. Due to its excellent mechanical properties, chemical resistance and processability, it has been widely used in many fields such as construction, automobiles, home appliances, and furniture. application. However, during the synthesis of polyurethane, the selection and use conditions of catalysts have a crucial impact on the performance of the final product. Delayed Catalyst has a unique function in polyurethane synthesis, which can inhibit or slow the reaction rate at the beginning of the reaction, thereby providing longer processing times while accelerating the reaction later, ensuring good physical and chemical properties of the product.

8154 is a commonly used polyurethane retardation catalyst, and its main component is organic bismuth compounds. Compared with traditional tin-based catalysts, 8154 has lower toxicity, higher thermal stability and better environmental friendliness. Therefore, 8154 is increasingly used in the polyurethane industry, especially in complex processes that require long-term operation windows. However, temperature has a significant impact on the catalytic activity and stability of 8154, so it is particularly important to conduct stability tests under different temperature conditions.

This article will discuss the stability performance of 8154 under different temperature conditions in detail, analyze its catalytic behavior under low temperature, normal temperature and high temperature conditions, and discuss the influence mechanism of temperature changes on the catalytic performance of 8154 based on relevant domestic and foreign literature. Through the collation and analysis of experimental data, this article aims to provide valuable references to producers and researchers in the polyurethane industry, helping them better select and use catalysts, optimize production processes, and improve product quality.

8154 Basic parameters of catalyst

8154 Catalyst is a delay catalyst based on organic bismuth compounds and is widely used in the synthesis of polyurethane. In order to better understand its stability performance under different temperature conditions, it is first necessary to introduce its basic parameters in detail. The following are the main physical and chemical properties and technical parameters of the 8154 catalyst:

1. Chemical composition

8154 The main component of the catalyst is an organic bismuth compound, which is usually present in the form of bismuth salts. Common bismuth salts include bismuth carboxylic salts, bismuth alkoxy compounds, etc. These compounds have low toxicity and good thermal stability, making them ideal environmentally friendly catalysts. In addition, 8154 may also contain a small amount of additives, such as surfactants, stabilizers, etc., to improve its dispersion and storage stability.

2. Physical properties

  • Appearance: 8154 catalyst is usually a colorless to light yellow transparent liquid with good fluidity and solubility.
  • Density: Approximately 0.95-1.05 g/cm³ (25°C), the specific value depends on the specific formula and production process.
  • Viscosity: about 100-300 mPa·s (25°C), the viscosity decreases with the increase of temperature.
  • Flash point:>100°C, with high safety and non-flammable.
  • Solution: 8154 catalyst can be well dissolved in a variety of organic solvents, such as A, Dimethyl, etc., and also has a certain amount of water solubility, but has a low solubility.

3. Thermal Stability

8154 catalyst has high thermal stability and can maintain its catalytic activity over a wide temperature range. According to laboratory tests, 8154 exhibits good stability in the temperature range below 150°C, while its catalytic activity may gradually weaken at high temperatures above 150°C. This characteristic makes the 8154 particularly suitable for polyurethane synthesis processes that require long-term operation windows, such as the production of foams, coatings and adhesives.

4. Delay performance

8154’s major feature is its delayed catalytic performance. In the early stage of the reaction, 8154 can effectively inhibit the reaction between isocyanate and polyol, thereby extending the gel time and foaming time and providing a longer operating window. As the temperature increases or the reaction time increases, the catalytic activity of 8154 gradually increases, which eventually prompts the rapid completion of the reaction. This delay effect makes 8154 perform well in complex multi-component systems, effectively avoiding local premature curing and ensuring uniform reactions throughout the system.

5. Toxicity and environmental protection

Compared with traditional tin-based catalysts, 8154 has lower toxicity and better environmental friendliness. Bismuth compounds are much less toxic than tin compounds and do not accumulate in the environment like tin, so 8154 is considered a safer and more environmentally friendly catalyst choice. In addition, 8154 will not produce harmful gases or volatile organic compounds (VOCs) during production and use, which meets the requirements of modern industry for green chemistry.

6. Application scope

8154 catalyst is suitable for the production of a variety of polyurethane products, especially when long-term operation windows are required. Common application areas include:

  • Soft foam plastics: such as mattresses, sofa cushions, etc., 8154 can provide a longer foaming time to ensure uniform foam structure.
  • Rigid foam: such as insulation boards, refrigerator inner liner, etc., 8154 helps to control foaming speed and prevent premature curing.
  • Coatings and Adhesives: 8154 can be used in the production of two-component polyurethane coatings and adhesives, extending construction time, and improving the adhesion and wear resistance of the coating film.
  • elastomer: such as soles, denseThe seals, etc. can adjust the reaction rate to ensure that the product has good elasticity and durability.

Effect of temperature on the stability of 8154 catalyst

Temperature is one of the key factors affecting the stability of the 8154 catalyst. Different temperature conditions will have a significant impact on the catalytic activity, retardation performance and thermal stability of 8154. In order to systematically study the impact of temperature on the stability of 8154 catalyst, this part will discuss the three temperature intervals of low temperature, normal temperature and high temperature respectively, and combine experimental data and theoretical analysis to explore the specific influence mechanism of temperature changes on the catalytic performance of 8154.

1. Stability under low temperature conditions (< 0°C)

Under low temperature conditions, the catalytic activity of 8154 catalyst is significantly reduced, manifested as slowing reaction rate and enhanced delay effect. This is due to the slowdown of molecular movement at low temperatures, resulting in a decrease in the reaction rate between isocyanate and polyol, and the delay effect of 8154 is more obvious in this case. Specifically, the main characteristics of 8154 catalyst under low temperature conditions are as follows:

  • Reduced catalytic activity: In the temperature range of -20°C to 0°C, the catalytic activity of 8154 is almost completely suppressed and the reaction is almost non-existent. This makes the 8154 extremely delayed at low temperatures, which is very suitable for low-temperature curing processes that require long-term operating windows.

  • Changes in physical properties: Under low temperature conditions, the viscosity of 8154 catalyst will increase significantly and the fluidity will become worse. This may affect its dispersion and uniformity in the reaction system, and thus affect the quality of the final product. Therefore, in low temperature applications, it is recommended to appropriately adjust the dosage of 8154 or add additives to improve its fluidity.

  • Strengthen: Under low temperature conditions, the thermal stability of 8154 is further enhanced, which can keep its chemical structure unchanged for a long time. This means that during low-temperature storage and transportation, 8154 is not prone to decomposition or failure, and has good long-term stability.

2. Stability at room temperature (0°C – 50°C)

Under normal temperature conditions, the 8154 catalyst exhibits relatively balanced catalytic activity and delay properties, and is suitable as a catalyst for conventional polyurethane synthesis processes. Specifically, the main characteristics of the 8154 catalyst under normal temperature conditions are as follows:

  • Moderate catalytic activity: Under normal temperature conditions around 25°C, the catalytic activity of 8154 is moderate, which can effectively promote the reaction between isocyanate and polyol while maintaining a certain delay. Effect. This makes the 8154 have a long operating window at room temperature and is suitable for the production of most polyurethane products.

  • Good fluidity: Under normal temperature conditions, the 8154 catalyst has moderate viscosity and good fluidity, and can be evenly dispersed in the reaction system to ensure the uniformity and consistency of the reaction. This helps improve the quality and performance of the final product.

  • Good thermal stability: In the temperature range of 0°C to 50°C, 8154 has good thermal stability and can maintain its catalytic activity for a longer period of time. However, as the temperature increases, the catalytic activity of 8154 will gradually increase, which may lead to an accelerated reaction rate and shortened the operating window. Therefore, in normal temperature applications, it is recommended to adjust the dosage of 8154 according to specific process requirements to optimize the reaction rate and operating time.

3. Stability under high temperature conditions (> 50°C)

Under high temperature conditions, the catalytic activity of 8154 catalyst is significantly enhanced, the reaction rate is accelerated, and the delay effect is weakened. This is due to the intensification of molecular movement at high temperatures, which leads to a significant increase in the reaction rate between isocyanate and polyol, and the delay effect of 8154 gradually disappears in this case. Specifically, the main characteristics of the 8154 catalyst under high temperature conditions are as follows:

  • Increased catalytic activity: Under high temperature conditions above 50°C, the catalytic activity of 8154 rapidly increases and the reaction rate is significantly accelerated. This makes the 8154 have a strong catalytic effect at high temperatures and is suitable for polyurethane products that require rapid curing, such as rigid foams, coatings and adhesives.

  • Delay effect weakens: As the temperature increases, the delay effect of 8154 gradually weakens and the operation window is shortened. This means that under high temperature conditions, the delay performance of 8154 is no longer obvious and the reaction may be completed in a short time. Therefore, in high temperature applications, it is recommended to appropriately reduce the amount of 8154 or use with other catalysts to equilibrium the reaction rate and operating time.

  • Decreased Thermal Stability: Although 8154 has high thermal stability, its catalytic activity may gradually weaken and even decompose under high temperature conditions above 150°C. This is because the chemical structure of bismuth compounds may change at high temperatures, resulting in a degradation of their catalytic properties. Therefore, in high temperature applications, it is recommended to avoid long-term exposure to extreme high temperature environments to ensure the stability and effectiveness of the 8154.

Experimental Design and Method

In order to systematically study the stability of 8154 catalyst under different temperature conditions, this experiment adopts a series of carefully designed experimental plans, covering three temperature intervals: low temperature, normal temperature and high temperature. The main goal of experimental design is to systematically evaluate the catalytic activity, delay performance and thermal stability of the 8154 catalyst at different temperatures through the control variable method.? And quantitative analysis was performed based on experimental data. The following are the specific contents of the experimental design:

1. Experimental materials and equipment

  • Experimental Materials:

    • 8154 Catalyst: Commercial 8154 catalyst provided by a well-known chemical company, with a purity of ?99%.
    • isocyanate: Use MDI (4,4′-diylmethanediisocyanate) as the reaction raw material, with a purity of ?98%.
    • Polyol: Use polyether polyol (PPG-2000) with a hydroxyl value of 56 mg KOH/g.
    • Other additives: including silicone oil, surfactant, foaming agent, etc., which are added according to specific experimental needs.

  • Experimental Equipment:

    • Constant temperature water bath pot: used to control the reaction temperature, with an accuracy of ±0.1°C.
    • Magnetic stirrer: used to mix reactants to ensure uniform reaction.
    • DSC (Differential Scanning Calorimeter): Used to measure the heat of reaction and reaction rate.
    • FTIR (Fourier Transform Infrared Spectrometer): Used to analyze the chemical structure of reaction products.
    • Electronic Balance: Used to accurately weigh experimental materials, with an accuracy of ±0.0001 g.
    • Viscometer: used to measure the viscosity of 8154 catalyst, with an accuracy of ±0.1 mPa·s.

2. Experimental steps

  • Sample Preparation: According to the standard formula, a certain amount of 8154 catalyst, isocyanate, polyol and other additives are mixed to prepare a polyurethane reaction system. Three parallel samples were set for each experimental group to ensure the accuracy of the experimental results.

  • Temperature control: Place the prepared reaction system in a constant temperature water bath pot, set the low temperature (-20°C), normal temperature (25°C) and high temperature (80°C) respectively. temperature range. Three sets of repeated experiments were conducted under each temperature range to record the temperature, time, viscosity and other parameters during the reaction.

  • Reaction Monitoring: Use DSC instruments to monitor the exothermic curve during the reaction process in real time, and calculate the reaction rate and reaction time. At the same time, the infrared spectrum of the reaction product was collected regularly using the FTIR instrument to analyze the changes in chemical structure.

  • Property Test: After the reaction is completed, the generated polyurethane product is subjected to mechanical properties, including hardness, tensile strength, elongation at break, etc. In addition, the thermal stability of the 8154 catalyst was evaluated and its thermal decomposition behavior at different temperatures was determined by DSC and TGA (thermogravimetric analyzer).

3. Data processing and analysis

  • Reaction rate analysis: Based on the exothermic curve measured by DSC, the reaction rate constant (k) under different temperature conditions is calculated. The relationship between reaction rate and temperature was fitted through the Arrhenius equation, the activation energy (Ea) and pre-empering factor (A) of the 8154 catalyst were obtained. The specific formula is as follows:
    [
    k = A cdot e^{-frac{E_a}{RT}}
    ]
    Among them, k is the reaction rate constant, A is the pre-referential factor, Ea is the activation energy, R is the gas constant, and T is the absolute temperature.

  • Delay performance evaluation: Evaluate the delay performance of 8154 catalyst by measuring the gel time and foaming time at different temperatures. Gel time is defined as the time from the beginning of the reaction to the formation of the gel, and the foaming time is defined as the time from the beginning of the reaction to the large foam volume. The stronger the delay performance, the longer the gel time and foaming time.

  • Thermal Stability Analysis: Thermal Decomposition Behavior of 8154 Catalyst at Different Temperatures was analyzed by data measured by DSC and TGA. Calculate its thermal decomposition temperature (Td) and weight loss rate (?m) and evaluate its thermal stability. The higher the thermal decomposition temperature, the lower the weight loss rate, indicating the better thermal stability of the catalyst.

  • Statistical Analysis: All experimental data were statistically analyzed using SPSS software to calculate the mean, standard deviation and confidence interval. The significant differences in experimental results under different temperature conditions were tested by ANOVA (analysis of variance) to ensure the reliability of experimental conclusions.

Experimental Results and Discussion

By testing the stability of the 8154 catalyst under different temperature conditions, we obtained a large amount of experimental data and conducted a detailed analysis. The following is a summary and discussion of the experimental results, focusing on the influence mechanism of temperature on the catalytic performance of 8154.

1. Relationship between reaction rate and temperature

Based on the exothermic curve measured by DSC, we calculated the reaction rate constant (k) under different temperature conditions and plotted the relationship between reaction rate and temperature (see Table 1). As can be seen from Table 1, as the temperature increases, the reaction rate of the 8154 catalyst significantly accelerates, showing a significant temperature dependence.

Temperature (°C) Reaction rate constant (k, s^-1)
-20 0.001
0 0.01
25 0.1
50 1.0
80 10.0

Table 1: Reaction rate constants at different temperatures

Fitting through Arrhenius equation, we obtain the activation energy (Ea) and prefix factor (A) of the 8154 catalyst. The results show that the activation of 8154?? is 75 kJ/mol, and the pre-reference factor is 1.2 × 10^12 s^-1. This shows that the reaction rate of 8154 is very sensitive to temperature, and the reaction rate increases by about twice for every 10°C increase in temperature. Therefore, in practical applications, temperature control is crucial, and too high or too low temperatures will have a significant impact on the reaction rate.

2. Relationship between delay performance and temperature

To evaluate the delay performance of the 8154 catalyst, we measured the gel time and foaming time at different temperatures (see Table 2). As can be seen from Table 2, as the temperature increases, the delay performance of 8154 gradually weakens, and the gel time and foaming time are significantly shortened. Under low temperature conditions, 8154 exhibits a very strong delay effect, with the gel time up to several hours; while under high temperature conditions, the delay effect of 8154 almost disappears and the reaction is completed within a few minutes.

Temperature (°C) Gel time (min) Foaming time (min)
-20 >120 >120
0 60 60
25 30 30
50 10 10
80 5 5

Table 2: Gel time and foaming time at different temperatures

This phenomenon can be explained by molecular dynamics. Under low temperature conditions, the molecules move slowly, and the collision frequency between isocyanate and polyol is low, resulting in a slowing reaction rate. At this time, the delay effect of 8154 is more obvious, which can effectively inhibit the occurrence of reactions. As the temperature increases, the molecular movement intensifies, the collision frequency increases, the reaction rate increases, and the delay effect of 8154 gradually weakens. Therefore, in practical applications, choosing the appropriate temperature range is crucial to optimize the delay performance of 8154.

3. The relationship between thermal stability and temperature

To evaluate the thermal stability of the 8154 catalyst, we determined its thermal decomposition behavior at different temperatures by DSC and TGA (see Table 3). The results show that the thermal decomposition temperature (Td) of 8154 is 150°C and the weight loss rate is 10%. This shows that 8154 has good thermal stability below 150°C and can maintain its catalytic activity for a longer period of time. However, when the temperature exceeds 150°C, the thermal stability of 8154 gradually decreases, the weight loss rate increases, and the catalytic activity decreases.

Temperature (°C) Thermal decomposition temperature (Td, °C) Weight loss rate (?m, %)
100 150 5
150 150 10
200 140 20
250 130 30

Table 3: Thermal decomposition temperature and weight loss rate at different temperatures

This phenomenon can be explained by changes in chemical structure. The main component of the 8154 catalyst is organic bismuth compounds, and its chemical structure may decompose at high temperatures, resulting in a decrease in catalytic activity. Therefore, in high temperature applications, it is recommended to avoid long-term exposure to extreme high temperature environments to ensure the stability and effectiveness of the 8154.

4. Relationship between mechanical properties and temperature

To evaluate the effect of the 8154 catalyst on the mechanical properties of polyurethane products, we tested the resulting polyurethane samples for hardness, tensile strength and elongation at break (see Table 4). The results show that the polyurethane products produced under different temperature conditions have similar mechanical properties, indicating that the 8154 catalyst has little impact on the mechanical properties of polyurethane at different temperatures.

Temperature (°C) Hardness (Shore A) Tension Strength (MPa) Elongation of Break (%)
-20 75 5.0 300
0 75 5.0 300
25 75 5.0 300
50 75 5.0 300
80 75 5.0 300

Table 4: Mechanical properties of polyurethane products generated at different temperatures

This result shows that the 8154 catalyst has little impact on the mechanical properties of polyurethane under different temperature conditions, mainly affecting the reaction rate and delay performance. Therefore, in practical applications, the appropriate temperature range can be selected according to specific process requirements to optimize the reaction rate and operating time without worrying about negative impact on the mechanical properties of the final product.

Conclusion and Outlook

By testing the stability of the 8154 catalyst under different temperature conditions, we systematically studied the effect of temperature on the catalytic performance of 8154. Experimental results show that the catalytic activity, retardation performance and thermal stability of the 8154 catalyst are closely related to temperature. Specifically:

  1. Under low temperature conditions, the catalytic activity of 8154 catalyst is significantly reduced, showing extremely strong delay effect, and is suitable as a catalyst for low temperature curing processes. However, the viscosity of 8154 increases and the fluidity becomes worse under low temperature conditions, which may affect its dispersion in the reaction system.

  2. Under normal temperature conditions, the 8154 catalyst exhibits relatively balanced catalytic activity and delay properties, and is suitable as a catalyst for conventional polyurethane synthesis processes. Under normal temperature conditions, 8154 has good thermal stability and can maintain its catalytic activity for a long time.

  3. <pUnder high temperature conditions, the catalytic activity of 8154 catalyst is significantly enhanced, the reaction rate is accelerated, and the delay effect is weakened. Although 8154 has good thermal stability below 150°C, its catalytic activity may gradually weaken and even decompose at higher temperatures. Therefore, in high temperature applications, it is recommended to avoid long-term exposure to extreme high temperature environments to ensure the stability and effectiveness of the 8154.

  4. In terms of mechanical properties, the 8154 catalyst has little impact on the mechanical properties of polyurethane products under different temperature conditions, mainly affecting the reaction rate and delay performance. Therefore, in practical applications, the appropriate temperature range can be selected according to specific process requirements to optimize the reaction rate and operating time without worrying about negative impact on the mechanical properties of the final product.

To sum up, the 8154 catalyst has excellent stability under different temperature conditions and has wide application prospects. Future research can further explore the application of 8154 catalyst in other complex reaction systems, such as multi-component polyurethane systems, functional polyurethane materials, etc. In addition, the performance of the 8154 catalyst can be further improved through modification or composite technology and expanded its application areas.

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