Preparation And Characterization Of NBC/Al Nano-Composite Materials

Aluminum powder has great advantages in solid propellants. It has the advantages of cheap, extensive source, high heat of combustion, and it can greatly enhance the energy and burning rate of solid propellants.But ordinary aluminum powder is easy to condense into droplets on the surface during combustion, therefore burning prolonged. Compared to ordinary aluminum powder, aluminum nanopowder can increase energy of solid propellant, improve combustion efficiency and combustion stability.Because of its smaller diameter,large specific surface area, the surface potential of aluminum nanopowder is very high and it easily reaction with the surrounding material, thus fade its application.Therefore, it has extremely practical significance to protect the activity of aluminum nanopowder. Nitrated bacterial cellulose(NBC)/ aluminum(Al)nano-composite materials are preparation with aluminum nanopowder and NBC as raw materials in this paper in order to protect the activity of aluminum nanopowder. And we also optimize the condition the preparation of NBC/Al nano-composite materials. The main experiment contents are as follows:(1)The preparation of NBC/Al nano-composite materials.NBC/Al nano-composite materials are preparation with aluminum nanopowder and NBC by solvent evaporation method and solvent/non-solvent method. The samples are characterized by XRD,SEM,EDS.The results show that the network structure of NBC collapse in NBC/Al nano-composite materials prepared by solvent evaporation method.The network structure of NBC collapse in NBC/Al nano-composite materials prepared by solvent/non-solvent method does not collapse, and aluminum nanopowder in close contact with NBC.(2)The influence on experiment product(NBC/Al nano-composite materials)was investigated systematically by dispersion time, mixing time, vacuum drying temperature and the ratio of NBC to aluminum nanopowder.The samples are characterized by XRD and DSC. The results show that NBC/Al nano-composite materials is better when the dispersion time is 15 minutes, stirring time is 3 hours,vacuum drying temperature is 35 ℃. And the higher the content of aluminum nanopowder, The higher the heat of the resulting sample release.(3)The change of heat and mass gain of different samples were investigated systematically. The samples are characterized by TG and DSC. The results show that the heat of the low-temperature exothermic peak increased to 7281 J?g-1from5437 J?g-1and the temperature of high-temperature exothermic peak advance to766.42℃ from 798.45 ℃ of aluminum nanopowder in NBC/Al nano-composite materials. And the heat and mass gain of aluminum nanopowder in NBC/Al nano-composite materials after a three-month ageing change little. The mass gain reduce to 42.64% from 51.50%,while the heat of low- and high- temperature exothermic peak reduce from 5437 J?g-1 to 3644 J?g-1 and from 3175J?g-1,respectively of pure aluminum nanopowder after a three-month ageing.