Introduction: The Rosary That Changed the World
Have you ever wondered what material thin women’s stockings, gears in heavy machinery, surgical sutures, and even astronaut safety systems are made of? This unique material is nylon , the first fully synthetic polymer that humanity was able to produce in large quantities, fundamentally changing industry and our everyday lives.
In February 1935, Wallace Carruthers, a young chemist at DuPont, synthesized a material that would forever change the textile industry. He and his research team at the DuPont laboratory in Delaware had long searched for a substitute for natural silk and finally developed a material superior in many ways. Nylon was unveiled at the 1938 World’s Fair in New York and quickly became one of the most successful industrial products in history.
Nylon is far more than just a textile material; today it is a class of polymer widely used in thousands of products – from clothing and carpets to car parts and medical devices – thanks to its high mechanical strength, flexibility, durability, and low price . In this article, we take a detailed look at the world of nylon: from its chemical properties and types to its diverse applications and the associated environmental issues.
What is nylon? And how is it made?
Scientific definition of nylon
Nylon is a synthetic polymer belonging to the polyamide family . The repeating units of the polymer chain are linked by amide bonds (which also occur in proteins). Nylon is a thermoplastic material , meaning it becomes soft and pliable when heated and solidifies again upon cooling.
Nylon is characterized by unique physical properties: a density of approximately 1.15 grams per cubic centimeter, a melting point between 190 and 350 degrees Celsius, and relatively low thermal conductivity. It is resistant to oils, solvents, and various chemicals, but sensitive to UV radiation and strong acids.
Manufacturing process: from monomer to fiber.
The production of nylon is a remarkable achievement of chemical engineering. Nylon is typically produced from two monomers: a diamine (a molecule with two amino groups) and a dicarboxylic acid (a molecule with two carboxyl groups) through a condensation reaction . The numbers following the nylon designation (e.g., Nylon 6, 66, 610, etc.) indicate the number of carbon atoms in these two monomers.
Nylon 66 is the most common type of nylon and is produced by the reaction of hexamethylenediamine (with six carbon atoms) with adipic acid (also with six carbon atoms). A brief description of the manufacturing process follows:
1. Salt formation : The two monomers are mixed with methanol as a solvent to form a nylon salt.
2. Polymerization : The purified nylon salt is heated in an autoclave (pressure vessel). Once the temperature reaches 270–280 °C, the water produced during the reaction is removed, and the polymer chains elongate.
3. Spinning : The molten polymer is forced through microscopic pores in cold air or ice water to form threads. These threads are then stretched and spun into textile fibers.
Nylon 6, developed by Paul Schlücke in Germany, is produced using a different process. In this process, the ring structure of a cyclic monomer called caprolactam is opened using heat and pressure to form polymer chains. This method is simpler than the one used to produce Nylon 66 and allows for better control over the quality of the final product.
Nylon types are classified according to material and intended use.
In the chemical industry, the term “nylon” refers to polyamide, but in the Iranian market and industry, it is often used for polyethylene products (such as garbage bags and plastic containers). This is an important conceptual distinction that should be noted.
1. Polyamide nylon (synthetic nylon and textile nylon)
This type of nylon is the original, invented by Carruthers and used in demanding industrial applications:
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Nylon 6 and 66 : The most common types of nylon, characterized by high tensile strength and good heat resistance. They are used to manufacture fibers for clothing, carpets, ropes, straps, and industrial components.
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The applications range from surgical suture material to automotive gears and parachute structures used in World War II.
2. Polyethylene nylon (nylon for packaging and agriculture)
In Iranian usage and in the packaging industry, thin polyethylene film is referred to as “nylon” and consists mainly of low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE) . These materials differ significantly from polyamide nylon and exhibit the following properties:
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Softness and flexibility : It is softer and more flexible than Nylex (HDPE).
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Transparency and brightness : It has a clear and bright appearance and is therefore ideal for packaging food and medical products.
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Low weight : The low density of these materials allows for reduced packaging weight and savings in shipping costs.
Depending on the area of application, this type includes the following types:
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Nylon bag with handles : a practical bag for carrying things (easy to carry, advertising can be placed on it).
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Nylon shrink film : Packaging for bottles and bulk goods (shrinkable and airtight).
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Vacuum nylon : used for packaging perishable products (prevents air from entering and extends their shelf life).
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Nylon is used in greenhouses : for greenhouse roofs, agricultural protective films (UV-resistant, up to 22 meters wide).
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Shock-absorbing nylon : Used for packaging delicate materials (the bubble wrap absorbs shocks).
PAC Persian Products Ply Aluminum Chloride (PAC)
Nylon is widely used in various industries.
Nylon has such a profound impact on various industries that we can hardly imagine life without it. Let’s look at the most important applications of this material:
Textile and clothing industry
Nylon revolutionized the fashion world. In the 1940s, nylon stockings for women were incredibly popular and often led to long queues outside shops. Today, thanks to its high elasticity, comfort, and quick-drying properties, nylon is widely used for sportswear, swimwear, socks, jackets, umbrellas, and backpacks.
automotive industry
Nylon is a lightweight and durable material, making it ideal for the automotive industry. Nylon-6 is used to manufacture components such as gears, connectors, bearings, cable sheathing, and fuel tanks. Using nylon instead of metal contributes to weight reduction and fuel savings.
Packaging industry (polyethylene sector)
As already mentioned, polyethylene nylon is widely used in packaging:
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Food products : Packaging of bread, dried fruit, nuts, vegetables and frozen food.
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Personal hygiene products : diaper packs, wet wipes, cosmetics and hygiene products for children.
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Industrial application : The technology for shredding wooden pallets is used for packaging electronic components and devices, as well as large wooden pallets.
Agriculture and greenhouses
Wide-mesh nylon fabric plays a crucial role in increasing the efficiency of food production in agriculture. It is used as greenhouse covering (to create controlled climate conditions), as polyethylene film (to prevent weed growth and retain soil moisture), and in silage (to preserve feed).
Medicine and Health
Nylon is widely used in medicine due to its excellent biocompatibility and high strength. One of its most important applications is in surgical sutures . Nylon is also used to manufacture certain disposable medical products and coatings.
Environmental problems: From the industrial revolution to the global crisis
No article about plastics and nylon would be complete without mentioning their negative impacts. Nylon is very popular due to its strength and durability , but precisely for this reason, it poses a serious threat to the environment.
Non-biodegradable nature
A typical plastic bag can remain in the environment for 100 to 500 years . Polyamide nylon has a similar lifespan. During this time, these materials decompose into microplastics , which then enter soils, groundwater, and oceans, polluting the food chain.
Iran’s garbage problem
Unfortunately, Iran’s waste management system suffers from serious structural problems. Many experts attribute this to centralized administration and insufficient citizen participation , leading to an unequal distribution of recycling profits. As a result of these problems, large quantities of nylon and plastic end up in the environment or in landfills.
New solution: biodegradable plastics.
Fortunately, science and technology offer solutions to this problem. Biodegradable plastics have proven to be a promising alternative. These materials are designed to be broken down by microorganisms into water, carbon dioxide, and biomass under certain conditions, such as suitable humidity and temperature.
The most important types of these materials are:
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Polylactic acid (PLA) : is produced from cornstarch or sugar cane . It is used to manufacture disposable containers and packaging.
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Polyhydroxylated fatty acid esters (PHAs): are produced by bacteria under certain conditions .
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Starch compounds : Mixtures of starch and biodegradable polymers.
Important note : The term “biodegradable” does not mean ” water-soluble ” or “self-degrading.” Many of these plastics require specific conditions (temperatures above 50°C and controlled humidity) to degrade . If these materials are dumped into the ocean, they may not decompose as quickly as desired.
Comparison of conventional plastic and biodegradable plastic.
| Special feature | Traditional plastics (nylon, polyethylene) | biodegradable plastic |
|---|---|---|
| Raw materials | Crude oil and natural gas (non-renewable resources) | Plants (corn, sugarcane) and renewable resources |
| Average life expectancy in the wild | centuries | From several months to several years (depending on the specific circumstances) |
| The final product | Microplastics and toxic materials | Water, carbon dioxide and harmless biomass |
| Current usage | Sacks, cheap packaging, agriculture | Food packaging, biodegradable bags, medical devices |
Waste recycling: The path to a circular economy
Recycling is the ideal solution after plastics production. Recycling transforms waste into new products, thus avoiding the waste of resources and energy.
Two methods are typically used in the recycling of nylon and plastics:
1. Closed-loop recycling : Conversion of waste into products of the same or higher quality.
2. Open-loop recycling : Conversion of materials into lower-quality products; for example, recycling nylon film into low-grade granules for the production of garbage bags.
Despite the enormous potential for plastic recycling in Iran, a significant portion of this valuable material does not enter the recycling loop. This is due to inadequate infrastructure for waste sorting at the source and a lack of public awareness.
The future of nylon: On the path to greater sustainability
The future of the nylon industry depends on preserving its unique properties while minimizing its negative environmental impact . Global trends indicate the following:
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Bio-nylon production : Researchers are working on using plant-based raw materials to produce polyamides that combine the strength of conventional nylon with renewable energy.
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Improved recyclability : Development of products that are easy to disassemble and recycle.
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Stricter laws : Many countries have banned single-use plastic bags and made the use of biodegradable alternatives mandatory.
In conclusion
The story of nylon is the story of a material indispensable to modern civilization. Originally developed as a substitute for silk, nylon has become a cornerstone of modern industry. From the deep sea (ropes and fishing nets) to the highest mountain peaks (mountaineering apparel), nylon proves its unsurpassed quality.
But decades of overuse have taught us that what is abundant in nature often comes at the highest price . Plastic pollution has become a global crisis, and nylon is one of its symbols.
The solution is not to abandon nylon entirely or to follow current trends. Rather, it lies in responsible consumption, increased recycling, and the development of environmentally friendly alternatives . As consumers, we have a responsibility to reduce our plastic bag consumption, properly separate waste, and choose products with eco-friendly packaging. These seemingly simple measures will together have a profound impact on the future of our planet.
Nylon, the revolutionary material of the 20th century, must learn to live in harmony with nature in the 21st century.