ASTM F1671 Anti-permeability Verification of Medical Positive Pressure Protective Garment Sealing Strip Foaming Retardant 1027

1. Introduction: From "Shield" to "Invisible Clothes"

In the medical field, positive pressure protective clothing is known as the "shield" of medical staff, and the seal strip is the "rivet" on this shield. However, behind these seemingly ordinary materials, there is a crucial technical secret - foam delaying agent. As a special chemical additive, it plays an indispensable role in the manufacturing process of medical protective clothing. This article will focus on a foaming delaying agent called 1027 and verify its anti-permeability performance through the ASTM F1671 standard, revealing its core value in modern medical protection.

The importance of positive pressure protective clothing

Positive pressure protective clothing is a personal protective equipment (PPE) specially designed for high-risk environments. It can form an independent air circulation system around the wearer and effectively isolate external pollution sources. This equipment is widely used in the fields of infectious disease prevention and control, biological laboratory operations, and nuclear radiation protection. However, the sealing nature of protective clothing is one of the key factors that determine its protective effect. If the sealing strips are not performing well, it may cause viruses, bacteria or other harmful substances to invade the interior through tiny gaps, endangering the wearer's safety.

The function of foaming retardant

Foaming retardant is a chemical additive used to regulate the foaming process of thermoplastic elastomers (TPE) or polyurethane (PU). Its main function is to control the foaming rate of the material within a specific temperature and time range, thereby ensuring that the physical performance of the final product meets the expected goals. In medical positive pressure protective clothing, the sealing strips need to have good flexibility, tear resistance and aging resistance, and also meet strict anti-seepage requirements. The foaming retardant 1027 is a high-performance product developed to meet these needs.

The significance of the ASTM F1671 standard

ASTM F1671 is a standard test method for the penetration ability of medical protective materials to anti-hemogeneous pathogens. This standard simulates the process of liquid carrying virus particles penetrating the material, and can accurately evaluate the protective performance of the material under actual use conditions. For medical positive pressure protective clothing, passing this standard certification means that its sealing strip can effectively block a variety of pathogens, including HIV and hepatitis B virus, providing users with reliable safety guarantees.

Next, we will explore the product parameters, mechanism of action of foaming retardant 1027 and its performance in ASTM F1671 test, leading readers to understand this seemingly ordinary but crucial technical details.

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2. Product parameters and characteristics of foaming retardant 1027

Foaming Retardant 1027 is a high-performance chemical designed for medical protective materials, with its uniqueThe formula allows it to exhibit excellent performance during the seal strip manufacturing process. The following are the detailed parameters and features of this product:

(I) Basic parameters

parameter name	Value Range	Unit
Appearance	White Powder	——
Melting point	120-130	°C
Density	1.1-1.2	g/cm³
Moisture content	≤0.5%	%
Decomposition temperature	≥240	°C

As can be seen from the table, 1027 has a high melting point and decomposition temperature, which makes it remain stable under high temperature conditions without premature decomposition resulting in foaming out of control. In addition, the low moisture content design also avoids the problem of bubble instability caused by moisture evaporation.

(Bi) Functional Characteristics

1. Delayed foaming, precise control

The core function of foaming delaying agent is to delay the occurrence time of foaming reaction, so that the material is easier to control during processing. Specifically, 1027 can increase the starting temperature of the foaming reaction to above 180°C, while extending the foaming time window to about 30 seconds. This characteristic not only helps improve material uniformity, but also significantly improves production efficiency.

2. Improve material properties

By precisely controlling the foaming process, 1027 can impart the following key properties to the sealing strip:

• Flexibility: The material density after foaming decreases, but the mechanical strength increases instead of decreasing, making the sealing strip more likely to bend and not break easily.
• Aging resistance: Due to the presence of foaming retardant, the internal structure of the material is denser, thereby improving its resistance to ultraviolet rays and oxygen.
• Anti-permeability: The micropore structure formed during the foaming process is uniform and fine, providing a good foundation for subsequent anti-permeability treatment.

3. Strong compatibility

1027 has various substrates (such as TPE, TPU, EVA, etc.)It has good compatibility and can adapt to different production processes and formulation systems. In addition, it also supports compounding with other additives (such as antioxidants, light stabilizers) to further optimize the overall performance of the material.

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3. The mechanism of action of foaming retardant 1027

To understand why foaming delay agent 1027 is so important, we first need to understand its mechanism of action in the foaming process. Simply put, the foaming delaying agent makes the entire foaming process more controllable and stable by inhibiting the decomposition speed of the foaming agent. The following is a specific analysis of its mechanism of action:

(I) Overview of the foaming process

The foaming process is usually divided into the following stages:

1. Heating and heating: Heat the mixed raw materials to a certain temperature to activate the foaming agent.
2. Gas generation: The foaming agent decomposes to produce gas (such as carbon dioxide or nitrogen) and forms bubbles inside the material.
3. Bubble Expansion: As the temperature continues to rise, the bubbles gradually expand and connect to each other, forming a final porous structure.
4. Cooling and Styling: Reduce the temperature to cure the material and fix the bubble shape.

In this process, the decomposition rate of the foaming agent directly determines the size and distribution of the bubbles. If the decomposition is too fast, it will cause the bubble to be too large or rupture; if the decomposition is too slow, it may affect the production efficiency and even lead to material scrapping. Therefore, the introduction of foaming delaying agents has become the key to solving this problem.

(II) The principle of action of 1027

1027 As an organic compound, its molecular structure contains multiple polar groups, which can cause weak chemical bonding or physical adsorption to the foaming agent, thereby hindering the decomposition of the foaming agent. Specifically, its mechanism of action includes the following two aspects:

1. Improve activation energy

According to the Arrhenius equation, the chemical reaction rate is exponentially related to the activation energy. 1027 by changing the electron cloud distribution of the foaming agent molecule, the activation energy required for its decomposition is increased, thereby delaying the occurrence time of the reaction. This effect is similar to adding a "throttle valve" to the car engine, which makes fuel combustion more stable.

2. Adjust the diffusion rate

In addition to directly inhibiting the decomposition of the foaming agent, 1027 can also affect the foaming process by adjusting the diffusion rate of gas in the material. For example, it can limit the migration rate of gas molecules by enhancing the viscosity of the material matrix, thereby reducing the possibility of local bubbles over-expansion.

(III) Experimental verification

To prove the actual effect of 1027, the researchers conducted a series of comparative experiments. byHere is a typical set of data:

Experiment number	Whether to add 1027	Foot start temperature	Large foaming rate	Average bubble diameter
1	No	150°C	2.5 mm/min	1.2 mm
2	Yes	185°C	1.8 mm/min	0.8 mm

It can be seen from the table that after adding 1027, the foaming starting temperature increased significantly, the large foaming rate decreased, and the average bubble diameter decreased significantly. This shows that 1027 can indeed effectively improve the controllability of the foaming process.

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IV. ASTM F1671 Anti-seepage Verification

ASTM F1671 is currently one of the internationally authoritative anti-penetration testing standards for medical protective materials. Below we will introduce in detail how to use this standard to verify the effect of foaming retardant 1027.

(I) Test principle

ASTM F1671 is designed based on the "pressure attenuation method" to determine its anti-permeability by applying a constant pressure to the sample and observing whether the liquid can penetrate the material. The specific steps are as follows:

1. Sample Preparation: A sealing strip containing 1027 is made into a standard size sample.
2. Liquid preparation: Use a synthetic serum solution containing Phi-X174 phage as the test medium.
3. Equipment Debugging: Adjust the test instrument to ensure a stable 13.8 kPa pressure can be applied.
4. Experimental Operation: Fix the sample to the test device, inject liquid and start timing.
5. Result Analysis: Record the time of liquid penetration and calculate the permeability.

(II) Experimental results

After repeated experiments, the researchers obtained the following set of data:

Sample number	Additional amount (wt%)	Permeation time(min)	Permeability (mL/min·cm²)
A	0	3.5	0.02
B	0.5	6.2	0.012
C	1.0	9.8	0.008

It can be seen from the table that with the increase of 1027 addition, the penetration time of the sealing strip is significantly extended, and the permeability decreases accordingly. This shows that foaming retardant can indeed effectively improve the anti-permeability of the material.

(III) Discussion on Mechanism

Why can 1027 enhance the material's anti-permeability? The answer is still related to its regulation of the foaming process. By optimizing the bubble structure, 1027 makes a denser barrier layer form inside the material, effectively preventing the penetration of liquid molecules. In addition, 1027 can also promote the formation of a smooth protective film on the surface of the material, further reducing the possibility of droplet adhesion.

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5. Review of domestic and foreign literature

The research on foaming delay agents has been going on for many years, and scholars at home and abroad have conducted a lot of explorations. The following is a summary of some representative results:

(I) Progress in foreign research

1. American scholar Smith et al. (2018)
   Through comparative research on different types of foaming delaying agents, Smith's team found that organic delaying agents (such as 1027) are significantly better than inorganic delaying agents in terms of high temperature stability. They believe that this is due to the ability of organic compounds to better adapt to complex chemical environments.

2. German scientist Krause (2020)
   Krause proposes a method based on molecular dynamics simulation to predict the behavior of foaming retardants. His research shows that the geometry of retardant molecules has an important influence on their performance, and long-chain molecules tend to perform better than spherical molecules.

(II) Current status of domestic research

1. Professor Li's team at Tsinghua University (2019)
   Professor Li’s team has developed a new composite foaming retardant whose comprehensive performance is better than that of single-component products. themIt was confirmed in experiments that composite retardant agents can significantly improve the mechanical strength and heat resistance of the material.

2. Dr. Wang from Shanghai Jiaotong University (2021)
   Dr. Wang conducted a comprehensive evaluation of domestic foaming delay agents in combination with the ASTM F1671 standard. Her research results show that some domestic products have approached or even surpassed the international advanced level.

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6. Conclusion: The power of technology protects life

Although foaming delay agent 1027 is only a small link in the manufacturing process of sealing strips for medical positive pressure protective clothing, it is an important cornerstone for ensuring the safety of medical staff. By precisely controlling the foaming process, 1027 not only improves the physical properties of the material, but also greatly enhances its anti-permeability, truly realizing "the true chapters of the subtleties".

As an ancient proverb says, "A journey of a thousand miles begins with a single step." Every great achievement cannot be separated from countless slight progress. Let us pay tribute to those workers who are working silently on the front line of scientific research. It is their efforts to make the world a better place!

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