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A Chinese research team has succeeded in mimicking the thermal properties of polar bear fur, in order to develop a new type of fiber that has proven to give warmth when woven into a jacket.
The polar bear’s fur is considered exceptional in providing warmth within its icy environment, due to its unique structure that prevents heat from escaping and provides protection for the bear’s body from the cold.
During the study published on December 21 On patrol “Science”, researchers from the Department of Polymer Science and Engineering at Zhejiang University announced their success in drawing inspiration from this unique structure to develop the famous airgel fibers and give them the thermal properties of bear fur. These attempts were not successful previously due to problems in these fibers that the researchers succeeded in solving.
Old material and new use
Airgel fibers are a special type of material made from “airgel”, which is a gelatinous substance invented in the 1930s, and the liquid component in it is usually replaced with a gas, resulting in a solid material consisting mostly of air, which is lightweight and highly porous, and the fibers are created Of them by converting them into thin, flexible threads or fibres.
These fibers maintain some of the basic properties of airgel, such as their lightweight nature and great insulating capabilities, and are designed to be strong, yet very light, and are often used for their excellent thermal insulation properties.
These fibers can be woven in various industries that require lightweight, highly insulating materials, such as in materials manufactured for space purposes, as they are used in NASA spacecraft. However, in the past, there were two problems that prevented the use of these fibers in the manufacture of lightweight and voluminous clothing that provided warmth:
- 1- Moisture permeability: There is difficulty in allowing moisture to pass through the material, which may cause discomfort due to sweat or moisture being trapped next to the skin, leading to a damp and uncomfortable feeling.
- 2- Strength and durability: Since Airgel fibers initially lacked the strength and durability necessary for practical use in clothing, and were fragile and susceptible to damage, for example, they could not be washed in a washing machine, which prevented their use in everyday clothing.
How did the solution come from bear fur?
The researchers were inspired to solve the previous two problems by the polar bear’s fur, whose structure consists of the following:
- porous core:
Each strand of polar bear hair contains a hollow or porous core. These small, air-filled cavities within the hair act as insulators, trapping air and preventing loss of body heat. Because air is a poor conductor of heat, the presence of these air pockets within the hair helps create a barrier against the cold. .
- Dense crust:
Surrounding this porous core is a denser outer layer, or cuticle, of the hair. This outer layer provides protection and durability to the hair. It acts as a shield against the harsh arctic climate conditions, including wind and water, which helps maintain the integrity of the insulating air pockets within the hair. .
- Transparent properties:
In addition, the guard hairs – the longer outer hairs of a polar bear’s fur – have a transparent structure. This allows sunlight to penetrate the dark skin underneath. When sunlight reaches the bear’s skin, it can absorb heat, contributing to the bear’s overall body warmth.
Together, these advantages provide outstanding thermal insulation while maintaining strength and flexibility, which the researchers succeeded in emulating by using the freeze-spinning method, which is a technique used to create certain types of fibers or materials by exploiting the properties of freezing and spinning, and it consists of four stages:
- 1- Preparing the solution: A solution is prepared containing the material intended for spinning, and this solution usually contains specific properties that allow it to transform into a solid or fibrous structure.
- 2- Freezing: The initial solution is exposed to very low temperatures, causing it to freeze rapidly. This freezing process solidifies the solution into a semi-solid or gelatinous state.
- 3- Spinning: While the solution is in this frozen state, it is spun or processed in such a way as to transform it into fibers or filaments, which can include techniques such as extrusion through micro-nozzles, stretching, or other methods to shape the frozen material into the desired fibrous form.
- 4- Post-processing stage: Depending on the desired properties of the final product, additional steps may be taken after spinning to further enhance the properties of the fiber, and this can include treatments such as drying, curing or coating to improve strength, durability or other specific attributes.
Through this method of spinning, the researchers were able to employ the first three stages to create strong polymeric air fibers with lamellar pores. In the fourth stage, they coated them with a thin, stretchable rubber layer. The resulting coated airgel fibers achieved excellent thermal insulation performance, and were mechanically strong, making them suitable for… For knitting or weaving.
Properties of new fibers
During the study, the researchers conducted experiments on new fibers that mimic polar bear fur, and found that they were able to stretch up to 1,000% of the strain, which is a significant improvement compared to traditional airgel fibers, which achieve a strain of only 2%.
The ability of fibers to stretch at up to 1000% stress means that they are able to withstand a stretching force equal to 10 times their original length before breaking, and this characteristic is often referred to as “elongation at break”.
Fibers with high elongation at breakage have the ability to stretch significantly before reaching the breaking point, and this indicates their flexibility and ability to withstand stretching forces without immediate failure.
The new fibers also maintained their thermal insulation properties with minimal impact even after 10,000 repeated stretching cycles at 100% strain. Furthermore, the fibers were washable and dyeable.
Demo jacket…additional benefits
The researchers took an advanced step by producing batches of their fibers into long strands that they used to weave a jacket. They then tested the warmth of the jacket by exposing it to temperatures as low as -20 degrees Celsius, and found that the jacket showed thermal protection that was better than similar jackets made of down. Or wool or cotton.
Aside from exceptional warmth and lightweight nature, the new airgel fibers offer many other advantages revealed by the study, including:
- water resistant: Airgel fibers are naturally water-resistant, making them ideal for wet and snowy conditions.
- Breathable: Despite its insulating properties, it allows ventilation and prevents overheating and excessive sweating.
- Durability: It can withstand repeated use and washing without losing its insulating properties.
- Environmentally friendly: Its production has a lower environmental impact compared to traditional methods, which often include poaching polar bears to benefit from their fur, a problem that may disrupt the ecological balance in the sensitive ecosystem in the Arctic region, where bears play a crucial role in the food chain there, and therefore smuggling is prohibited. Polar bear skins or parts cross borders under international laws such as CITES, which prohibits international trade in endangered species of wild animals and plants.
Industrial application.. 3 questions
The success of experiments at the laboratory level – as the study showed – does not mean that the new fibers have become industrially applicable, says Khaled Salah, a researcher in the Textile Fibers Research Department at the Egyptian Agricultural Research Center.
Salah explains in a telephone interview with Al Jazeera Net that researchers need to answer 3 important questions:
- First: comfort and ease of wearing; How comfortable and easy to wear are clothes made from these new fibers?
- Second: Regulatory and safety considerations; Have there been studies or evaluations on the safety of wearing clothing made from these fibres, especially with regard to skin contact or potential allergens?
- Third: Practical application and ease of use; Are there any anticipated challenges in commercializing this technology for widespread use, and to what extent can these clothes be accessible to consumers?
