Application of the hottest intelligent thermosensi

2022-08-22
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Application of intelligent thermosensitive polyurethane in permeable materials

intelligent thermosensitive polymer is a kind of polymer material that can respond to the change of external temperature, that is, the change of external temperature promotes the predetermined response of the microstructure of the polymer, so that the specific macro properties of the polymer will change accordingly. It belongs to a kind of intelligent materials. Intelligent thermosensitive polymer is a kind of polyurethane material, and its intelligent thermosensitivity is shown in; When the external temperature changes, its moisture permeability also changes accordingly, especially like human skin, which can be adjusted with the change of external temperature and humidity. In particular, through molecular design, the temperature range where the permeability changes can be controlled within the room temperature range, which further expands the application of intelligent thermosensitive polyurethane in textile, medicine, environmental protection and other fields

research and development of intelligent thermosensitive polyurethane in 1992, HORII and others applied for a patent in Japan, claiming to have invented a polyurethane polymer with a glass transition temperature of 0 ~ 60 ℃, which is made into a film for textiles. The evaporation of body sweat to the outside world can be controlled by adjusting the moisture permeability at the glass transition temperature. This is the first public report on Intelligent thermosensitive polyurethane found so far

In 1993, Hayashi of Mitsubishi Heavy Industries (MHI), one of the inventors, published an article on journalofcoatedfabrics, introducing the microstructure of some high moisture permeable polyurethane materials, and tested the moisture permeability of the materials. The results showed that the moisture permeability of the materials increased nearly three times with the temperature in the temperature range of 10 ~ 40 ℃. The author's explanation is: when the temperature rises to the glass transition temperature, the micro Brownian motion of the molecular chain suddenly intensifies, resulting in a sharp increase in the free volume, which provides more ways for the passage of water vapor, resulting in a rapid increase in the moisture permeability of the polyurethane material; When the temperature drops below Tg, the micro Brownian motion of the molecular chain slows down, and the temperature permeability of the material will decrease. As the following topics of the forum are previewed, this gives the intelligent characteristics that the moisture permeability of the material changes with the change of external temperature

in 1998, in order to carry out the experiment department, the company established by MHI in New York, the United States, announced that it had developed intelligent fabrics for outdoor clothing. The fabric is compounded with a very thin non porous polymer film. At low temperature, the molecular chains of the polymer are closely arranged, which can prevent the outward transmission of water vapor and heat in the human body, so as to achieve the function of keeping warm; When the temperature rises to a predetermined range, the motion of the molecular chain suddenly intensifies, resulting in a sharp increase in the free volume, which provides more opportunities for the elimination of water vapor and heat in the human body, which helps to prevent uncomfortable and sticky feelings in the microenvironment in the clothing

in March, 2001, soldiers and biochemical laboratories of the U.S. Army announced that they had designed an amphibious clothing for land and sea. In water, the clothing can isolate water from contacting the skin and keep the body wet. Once it is separated from water, the change of the special microstructure of the clothing can make the sweat discharge in time. This is another application report of intelligent thermosensitive polyurethane

however, things are always changing. In August, 2002, the research team of Dr. Hu Jinlian from the Department of textiles and clothing of the Hong Kong Polytechnic University found that the moisture permeability of dia ple fabric did not change particularly within its TG range. On the contrary, when we applied the company to calculate the moisture permeability according to ASTM E standard to eliminate the influence of the increase of steam pressure with the increase of temperature on the moisture permeability, we found that the moisture permeability of the fabric decreased slightly with the increase of temperature

then, in October 2002, Dr. Gibson of the U.S. military Soldier System Center reported the same conclusion as ours at the American fiber society. According to the test results, the moisture permeability of various fabrics, including diaplex fabric and Gore Tex fabric, has not changed with the change of humidity

however, the research work of intelligent thermosensitive polyurethane has not ended here. From October to December 2002, through the cooperation of many parties, Dr. Hu Jinlian's research team redesigned the molecular structure of polyurethane material based on the principle of free volume, and synthesized a new polyurethane material. After testing, it was found that the material has the characteristics of intelligent thermal sensitivity, that is, its moisture permeability has a special change with the change of humidity in the design humidity section. The moisture permeability increases 3 ~ 5 times with temperature in the temperature range of 10 ~ 40 ℃

application prospect of intelligent thermosensitive polyurethane materials in fact, Mitsubishi Heavy Industries and the U.S. military have provided us with good application ideas. Intelligent thermosensitive polyurethane will be widely used in the textile field. Using this kind of intelligent heat sensitive polyurethane to produce intelligent waterproof and moisture permeable fabric can not only make the wearer more adapt to various outdoor environments, but also reduce the defects such as micropore blockage in the use process due to micropores

in addition, after testing, the free volume of the material changes from 4.95 to 5.75a at room temperature, which should be more widely used in medicine, separation/filtration industry and environmental protection. For example, in the pharmaceutical field of (4) pull back and impact button, it can be used as intelligent drug coating to realize the directional release of drugs. That is, taking advantage of the fact that the temperature of the affected part in the body is generally higher than that of other normal parts, at normal temperature, drugs traverse from the coating film 2. Curve traversal: the force value and deformation data of the experimental curve can be checked point by point, and the penetration rate is very low. When entering the affected area, the increased temperature will lead to a significant increase in the penetration rate of drugs from the coating film, so that most drugs can enter the affected part directly. This will help improve the efficacy and avoid adverse effects on other healthy parts of the human body. In the field of separation/filtration, intelligent polyurethane membrane should also have a large number of applications

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