In fact, the spaceship was very clean and tidy when it left the factory, but when it returned to Terrestrial Time after a period of space flight, the outside of the spaceship became "black". The Reentry capsule of Shenzhou 13 spaceship has been exhibited before, and there is a completely blackened and carbonized surface on the honeycomb like coating outside the Reentry capsule, which is the burning trace of the Reentry capsule when it enters the atmosphere. Such a big difference, when we know the truth, it makes people feel that the space flight journey is truly full of thrills. In fact, the exterior of the Reentry capsule has undergone special treatment. For example, the exterior is coated with some ablation materials and thermal insulation materials. Even if the external temperature reaches thousands of degrees Celsius, it will not burn the Reentry capsule. The internal temperature of the Reentry capsule is very comfortable, which will not threaten the safety of astronauts or affect the normal operation of Mars rover.
It is understood that when the Shenzhou Reentry capsule passes through the black barrier area, the high temperature burning time exceeds 6 minutes, and the comprehensive heat reaches 120000 kilojoules per square meter. Under the high temperature of thousands of degrees Celsius, if it is ordinary materials, even if the inner three layers and the outer three layers, the re-entry capsule has already been burned through, so it must use super strong thermal insulation materials.
After years of research, Chinese scientists have finally developed a new type of composite material that integrates insulation, heat prevention, and load-bearing. The new composite material is composed of phenolic hollow microspheres, glass hollow microspheres, reinforced fibers, and so on. The new composite material is filled into the strongest honeycomb structure according to a certain quota, forming a super strong thermal insulation material, forming a layer of safe "thermal protection" for the Reentry capsule.
Of course, in order to further enhance the thermal insulation capability of the thermal insulation materials, another layer of heat dissipation materials is added to the outer surface of the honeycomb structure of the Reentry capsule under high temperature, which is directly sublimated from the solid to the gaseous state. This process absorbs a lot of heat, and the residual heat is decomposed through the honeycomb structure. With this layer of heat dissipation material, even after being burned at a high temperature of 3000 degrees Celsius, the cabin will still be warm as spring, ensuring a temperature of around 25 ℃. However, this material will leave black marks during the decomposition process.
In addition to the super strong thermal insulation materials outside the Reentry capsule, Chinese researchers have also carried out a lot of research on thermal management fabrics and thermal protection materials in recent years. These innovative research and development achievements can keep the human body in a comfortable temperature range, provide a new direction for the development of wearable intelligent fabrics, and can be applied to the virtual world to sense the change of object temperature.
Efficient and durable molecular solar thermal management fabric
Improve energy utilization efficiency
Molecular solar energy storage materials (MOST) can effectively capture solar energy, store energy in Chemical bond through molecular isomerism, and release energy in the form of heat under the stimulation of light. Due to its integration of solar energy absorption, conversion, storage, and release, it has received widespread attention, especially in the field of personal thermal management. However, due to the problems of low energy density, easy leakage, and poor fastness of molecular solar energy storage materials, their application in energy storage fabrics is limited.
To solve the above problems, the research team of Jiangnan University and Shanghai Jiaotong University designed and synthesized pyrazolyl Azobenzene molecules. The introduction of a five membered ring structure containing heteroatoms can enable pyrazolyl Azobenzene molecules to have higher isomerization conversion and isomerization energy storage time. However, the high isomerization conversion rate of pyrazolyl azobenzene molecules requires monochromatic light stimulation response, and standard solar spectral irradiation can cause incomplete isomerization. Therefore, the encapsulation of pyrazolyl Azobenzene molecules into microcapsules with UV filtering performance not only solves the problem of leakage during the phase transition of pyrazolyl Azobenzene molecules, but also gives them the performance of high isomerization conversion under broad spectrum UV light. After 2000 times of energy charging and discharging, 50 times of water washing and 50 times of friction, the pyrazol based Azobenzene molecular energy storage fabric still has an efficient solar energy storage density.
Compared to environmental temperature control methods such as heating, ventilation, and air conditioning, efficient and durable molecular solar thermal management fabrics improve energy utilization efficiency, and use solar energy as an energy source to alleviate carbon emissions and pollution problems caused by fossil fuel consumption. They also provide an effective way to build a solar energy storage fabric that integrates solar energy absorption, conversion, storage, and controllable release.
Thermal responsive fibers for multifunctional thermal activated protective fabrics
Intelligent textiles with good thermal and mechanical adaptability are expected to play an important role in fields such as motion protection, fire rescue, and aerospace. However, the poor processability, comfort, and long response time of most reported thermal and mechanical adaptive polymers have limited their applications.
Recently, the Zhang Qinghong/Hou Chengyi team of Donghua University designed and continuously prepared a thermal response fiber with skin core structure (commercial fiber as core/temperature sensitive hydrogel as skin). The composite fiber showed rapid mechanical adaptability, good thermal hardening and thermal insulation properties.
In this study, researchers solved the problem of poor interfacial adhesion between commercial fibers and stimulus responsive hydrogels by constructing a covalent anchoring network, thus successfully coating the hydrogel skin evenly on a variety of commercial fibers, realizing large-scale continuous manufacturing of thermal responsive fibers. This method is universal and applicable to a variety of commercial fibers. The synergistic effect of hydrophobic interaction and ionic bond enables the tensile strength (0.65~16 MPa) and elastic modulus of the hydrogel skin to be automatically adjusted with the change of temperature. Therefore, the prepared thermal responsive composite fiber has the characteristics of soft and skin friendly at room temperature and hard and impact resistant at high temperature. In addition, due to the heat absorption effect of phase separation and ion interaction, the smart fiber can absorb a certain amount of heat in a high temperature environment (65 ℃~95 ℃), reducing the Apparent temperature by 18 ℃~27 ℃, thus achieving the effect of preventing thermal burns. Therefore, this intelligent fiber is expected to be used in fields such as sports protective equipment and thermal protective clothing.
Wet spinning and vacuum impregnation preparation for
Flexible thermal storage phase change non-woven fabric for wearable fabrics
It is reported that the team of Shi Quan, a researcher of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Wu Zhongshuai and Chen Ying, a professor of Deakin University in Australia, have made new progress in the research of flexible fiber type phase change materials. The cooperation team has prepared flexible Graphene Boron nitride fiber based phase change non-woven fabric through wet spinning and vacuum impregnation, which has excellent flexibility, heat storage capacity, and air permeability, and is used in wearable human thermal management devices.
Phase change energy storage materials can absorb and release a large amount of phase change latent heat at relatively constant temperatures, and can be used as thermal energy storage and temperature control media in the field of human thermal management. However, the inherent characteristics of traditional phase change materials such as easy liquid leakage, poor breathability, and solid rigidity make it difficult to apply in wearable intelligent thermal management devices.
In order to further improve the gas permeability and energy storage density of phase change devices, Shi Quan's team, using the preparation technology of Graphene three-dimensional porous assembly of Wu Zhongshuai's team and the unique advantages of Chen Ying's team in the field of Boron nitride nano sheet preparation, jointly proposed a general strategy for preparing high enthalpy flexible phase change non-woven fabrics through wet spinning. This phase change non-woven fabric exhibits a high enthalpy value of 206.0 joules per gram, excellent thermal stability, thermal cycling ability with an enthalpy retention rate of 97.6% after 1000 cycles, and ultra-high water vapor permeability, which is superior to the currently reported phase change material films and fibers.
Fiber pump embedded in fabric can sense temperature changes in the virtual world
Researchers from the École Polytechnique Fédérale de Lausanne in Lausanne, Switzerland, have developed a pump in the form of fiber. This fiber pump can be directly stitched onto textiles and clothing. It is lightweight, powerful, and washable. This innovation can be applied to fields from Exoskeleton to virtual reality.
This study was conducted on the basis of a scalable pump developed by researchers in 2019. The optical fiber form enables researchers to manufacture lighter and more powerful pumps, which are more compatible with Wearable technology. In order to achieve the unique structure of the pump, researchers have developed a new manufacturing technology by wrapping copper and polyurethane wires around steel rods and then melting them hot. After removing the steel rod, standard weaving and sewing techniques can be used to integrate 2mm fibers into the textile. This type of pump is essentially a pipeline that can generate its own pressure and flow rate.
The simple design of this pump has many advantages. The required materials are cheap and easy to obtain, and expanding the manufacturing process is also relatively easy. Due to the direct correlation between the pressure generated by the pump and its length, the pipeline can be cut according to the application situation, thereby optimizing performance while minimizing weight. The sturdy design also makes it suitable for traditional detergent cleaning.
The study also showed the Artificial muscle made of fabric and embedded fiber pump, which can be used to power the soft Exoskeleton and help patients move and walk. The pump can even bring new dimensions to the virtual reality world by simulating temperature sensation. In this situation, the user is wearing a glove, and the pump on the glove is filled with hot or cold liquid, allowing the user to feel the temperature changes when in contact with the virtual object.
source:https://www.tnc.com.cn/info/c-001001-d-3732509.html