Experimental Study On Thermal Conductivity Of Modified Silk With Carbon Materials

Silk,as a kind of protein fiber,has excellent properties,such as fire resistance,heat resistance,biocompatibility,mechanics,biodegradability and is widely used in textile,tissue engineering,biomedical and other fields.In recent years,the application of silk fiber in the field of biomedical field devices is becoming more and more extensive,but silk still does not meet the high requirements in thermal and force performance.The thermal properties of silk is an important performance index in the application of artificial skin of silkworm in the field of biomedicine,so changing the thermal conductivity of silk has become the focus of the research.Many researchers have developed the application scope of silk by modifying silk,in which the commonly used methods of modified silk are physical modification and chemical modification.While these methods are usually not perfect due to the complicated steps,high cost,environmental pollution and other problems.Therefore,this study uses a relatively novel method which is the feeding method of feeding the particles,and proves that the modified silkworm can be used to feed silkworm carbon materials.Different from the traditional method,the method in this study will not damage the natural quality of silk,and the modification effect is remarkable,simple and controllable,low in cost,green and sustainable,and has the prospect of industrialization.In recent years,the application of silk fiber in biomedical field is more and more extensive,but the thermal properties and mechanical properties of silk can not reach the ideal state of practical application requirements.The thermal properties of silk are important performance indicators for biomedical materials.Therefore,changing the thermal conductivity of silk has become the current stage of research.A key.Many researchers have developed the application range of silk by changing the performance of silk.However,the common methods of silk modification have some problems,such as complicated steps,high cost,environmental pollution and so on.Modified silk,this method will not only not damage the natural quality of silk,the modification effect is remarkable,and simple and controllable,low cost,with industrial prospects.By feeding fourth-instar silkworms with mulberry leaves with nano-graphene,single-walled carbon nanotubes and nano-graphite particles,this study aims to discover the growth and silkworm appearance of silkworm fed with carbon materials.The results showed that after feeding mulberry leaves with nano-graphene,single-walled carbon nanotubes and nano-graphite particles,the morbidity,body shape,feeding rate,cocoon size,color and diameter of monofilament did not change significantly.It is concluded that mulberry leaves fed with nano-carbon materials from the fourth instar of silkworm are non-toxic to silkworm and will not cause adverse effects on the growth of silkworm.On this basis,this research will further study the effect of carbon nanomaterials on thermal conductivity of modified silk.The mulberry leaves with a mass per unit area of 130 mg/m²,260 mg/m²and390mg/m² nanographene,single-walled carbon nanotubes and nano-graphite particles were fed to the fourth-instar silkworm to obtain the modified silk as an experimental group,to study on thermal conductivity of modified silk.The modified silk was obtained through cocoon processing and degumming.The thermal conductivity of modified silk monofilament was studied by transient electrothermal technique?TET?,and the thermal diffusivity of modified silk monofilament was obtained.The thermal conductivity of pure mulberry leaves in comparison group is 0.75 W/m^-1K^-1.The modified silkworm obtained from feeding Nano graphene with a mass per unit area of 390 mg/m²,the thermal conductivity is 0.65 W/m^-1K^-1,which is 14%lower than that of the contrast group.The thermal conductivity of modified silk fed with 390 mg/m² single-walled carbon nanotubes was 17%lower than that of the control group,and the thermal conductivity of modified silk fed with 390 mg/m² graphite powder was 25%lower than that of the control group.The results showed that the thermal conductivity of silk fed with mulberry leaves with carbon addition was lower than that fed with pure mulberry leaves.Moreover,the greater the amount of carbon added in mulberry leaves,the lower the thermal conductivity of modified silk.The modified silk monofilament after degumming and pure mulberry leaf monofilament were analyzed by Raman spectroscopy.It was found that the number and size of the crystalline region of silk fibroin protein were reduced by feeding silkworm nano-carbon materials.The crystalline phase has higher thermal conductivity than the amorphous phase,so the thermal diffusivity of silk modified by carbon material is reduced.Scanning electron microscopy?SEM?analysis of degummed silk showed that carbon nanoparticles had little effect on the morphology of silk,and no nanoparticles were found on the surface of degummed silk.This study can prove that the silkworm rearing method by adding nanoparticles will not damage the quality of silk.Meanwhile,the method is simple and easy to operate and has no impact on the environment,and the effect of modified silk is remarkable and can be extended to a large-scale production.