Spider silk conducts heat conversely, being resistant to most organic materials researched.

by dekokfo032 on 2012-03-08 15:04:57

Several experiments were conducted by Mr. Wang with partial support from the Army Research Office and the National Science Foundation of the United States. Mechanical engineers Xiaopeng Huang, Liu, and others assisted in discovering the unique capability of spider silk in heat conduction, which made Mr. Wang very excited. "I think we are trying the right material," he concluded. In his paper titled "New Secrets: Abnormally High Thermal Conductivity of Spider Silk and Its Anomalous Changes Under Tension," recently published in the journal Advanced Materials, Mr. Wang found that the heat conduction of spider silk is much higher than most materials, including conductors such as silicon, aluminum, and pure iron. The research team also discovered that spider silk conducts heat 1000 times more effectively than woven silk from silkworms and 800 times more effectively than other organic tissues.

Mr. Wang believes that his discovery will change how scientists perceive organic materials and thermal conductivity. "Our discovery will revolutionize the traditional thinking about low thermal conductivity of biological substances," he wrote on a Shantou website promotion page. Using experimental methods and "time and patience," Wang Jianmin found that the rate of heat transfer through spider silk is 416 watts per meter kelvin. In comparison, copper transfers heat at a speed of 401 watts per meter kelvin, and skin tissue transfers heat at a speed of 6 watts per meter kelvin in the United States. "This is very surprising because spider silk is an organic substance," Mr. Wang admitted. "Among organic materials, this is the highest ever. Only a few materials have a higher thermal conductivity - silver, diamond," he added. Mr. Xiaomin also revealed that the thermal conductivity coefficient of spider silk increases when it is stretched. In fact, if spider silk is extended by 20%, its conductivity increases by 20%. Generally, stretching materials would decrease their conductivity. This discovery "opens a door to adjust the thermal conductivity of soft materials as another option," Mr. Wang Jianmin wrote in his article.

Mr. Wang Jianmin's discovery has multifaceted impacts on military, electronic entertainment devices, industrial, and medical fields. Mr. Wang has been looking for organic materials that can transfer heat like metals throughout his career. Thermal conductivity, or the ability of a material to transfer heat, is excellent in materials like diamonds, copper, and aluminum; however, most organic materials do not possess this capability. Several characteristics of spider silk made Mr. Wang Jianmin want to test its heat transfer ability. Spider silk is extremely strong. In fact, the strength of spider silk matches that of high-grade alloy steel. Spider silk is only 4 micrometers thick, while human hair is approximately 60 micrometers thick. Mr. Wang was the first scientist to test spider silk for its heat transfer capability.

Spider silk, closely studied by Mr. Wang Jianmin, is a protein fiber spun by spiders. Using silk, spiders create webs that function as traps for insects. Spiders can also use their own silk to build cocoons or nests for their babies or as safety lines. A spider can swing itself using its silk even though it may be many times heavier than its silk.

To determine the heat transfer capability of spider silk, eight male spiders (Nephila clavipes or golden silk) were housed in cages at a greenhouse in Iowa State University. Mr. Wang threw male spiders into the cages and let them eat crickets. There are many purposes for spider silk. Recently, NewScientist reported that spider silk was spun into violin strings. "Strands of spider silk used to make violin strings have a unique, exciting sound," Stephen Battersby of NewScientist wrote.

Spider silk conducts heat unlike most organic materials, according to a press release from Iowa State University on Friday. Xinwei Wang, an associate professor of mechanical engineering at Iowa State University, found his curiosity piqued after discovering that spider silk performed best under certain conditions.