Preparation And Performance Study Of Lightweight Ultra-fine Fiber Sponge For Heat Retention

Human function would be seriously damaged in extremely cold environment,so thermal insulation materials are very important to our lives.Traditional thermal insulation materials are usually made of cotton,wool and down feather,which are easy to absorb moisture and damaged by worms.Synthetic fibers have advantages over natural fibers in terms of moisture-proof and moth-proof,but the common problem is that their fibers are still larger than 10?m in diameter,which makes it impossible to achieve lower volume density and higher thermal performance at the same time.Electrospinning fiber is light and fine,and it has great potential in the field of thermal insulation.However,electrospun materials are usually stacked tightly and too thin to hold large amounts of still air.Therefore,it is of great significance to fabricate three-dimensional electrospinning fibrous materials with high elasticity and stable structure.The structure of available fiber sponge is not adjustable,which makes the thermal performance of the sponges cannot be guaranteed.To solve these problems,fiber sponge with controllable structure was successfully prepared by the moisture-assisted electrospinning technology in this paper.Specific research and analysis are as follows:(1)The fiber sponges with fluffy structure based on PAN,PMMA,PSU and ABS were successfully prepared by electrospinning.The forming mechanism of the fluffy structure was investigated,the results showed that the phase separation ability was the main reason for the difference of the fluffy structure of the sponges.Among these fibrous sponges,PSU fibrous sponge has relatively low volume density and preferable mechanical properties.On this basis,we further studied the effect of polymer concentration on the structure of sponges.With the increase of PU concentration,the fibrous morphology became more regular and the diameter also increased.When the concentration of PSU was 22wt%,the sponge has the best thermal insulation performance(thermal conductivity=26.02 m W m^-1 K^-1).(2)PU was introduced to improve the stability of the fluffy structure of sponge.PSU/PU fibrous sponge has excellent elasticity and strength,which can resist external forces.By further regulating the PU content,we found that the mechanical properties of sponge were improved with the increase of PU content,while the fluidity of sponge was just the opposite.Because the phase separation rate of mixed solution was reduced.When the ratio of PSU/PU was 8/2,the sponge still maintains three-dimensional structure,the tensile strength reaches 260 k Pa,and the plastic deformation was only 6.1%after 100 compression cycles,which shows excellent fatigue resistance.(3)In order to reduce the residual solvent,low-boiling solvent was used to accelerate solvent volatilization and reduce the bond between fibers.The prepared sponge with high fluidity structure(volume density=2.98 mg cm^-3)was obtained,which has excellent mechanical properties(tensile strength=332 k Pa).And it also has good insulation properties(thermal conductivity=25.52 m W m^-1K^-1).(4)Electrospinning fiber sponges have good thermal performance in different environments.And the thermal resistance of the sponge at 58 g m^-2 was 0.31 m² K W^-1,which was significantly better than commercial sponges.In addition,we designed a new electrospinning nozzle.By simulating the electric field of the nozzle,the optimal electric field distribution was obtained when the needle length was 8 mm and the number of needles was 8.This new electrospinning nozzle can increase the uniformity of electric field and further promote the output,which provides new ideas for the development of electrospinning nozzles.