Preparation, Characterization And Thermal Analysis Of 2MgO·B 2 O 3 ·1.5H 2 O And Its Nanocomposites

Borate is an effective and inexpensive inorganic flame retardant,which has many advantages,such as high thermal stability,no toxicity,no smoke,no pollution to the environment and low cost.If the borate flame retardant reaches nanoscale,it is possible not only to increase the contact surface between the flame retardant and the matrix material,which can improve the compatibility between the materials,but also to reduce the amount of flame retardant.Up to now,there are few reports on the preparation of nano structured magnesium borate and its flame retardant properties.Therefore,it is of great practical significance to study the preparation,characterization and flame retardant properties of magnesium borate and magnesium borate composite materials.In this paper,2MgO·B2O3·1.5H2O nanomaterials with different morphologies were prepared by hydrothermal/solvothermal method,and 2MgO·B2O3·1.5H2O/Mg(OH)2 nanocomposite were prepared by situ reaction.The products were characterized by X-ray diffraction(XRD),infrared spectroscopy(FT-IR),thermogravimetric analysis(TG),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The flame retardancy of2MgO·B2O3·1.5H2O samples with different morphologies and 2MgO·B2O3·1.5H2O/Mg(OH)2 nanocomposite were studied by thermal analysis and the limiting oxygen index method.The specific contents are as follows:(1)2MgO·B2O3·1.5H2O nanorods and nanowires were prepared by hydrothermal method,and 2MgO·B2O3·1.5H2O short nanorod was prepared by solvothermal method at lower temperature and shorter time.In addition,the effects of other factors such as surfactants and organic solvents on the morphology were investigated.The samples of 2MgO·B2O3·1.5H2O with different morphologies such as nanobelts,nanostrips,nanofiber and nanorafts were obtained,which were characterized by XRD,FT-IR,SEM and TEM.(2)The flame retardant properties of 2MgO·B2O3·1.5H2O samples with different morphologies were studied by thermal analysis and the limiting oxygen index method.As a contrast,non-nanostructure 2MgO·B2O3·1.5H2O sample was also prepared.We also employed the Kissinger’s method to obtain the apparent activation energy(Ea)in the thermal decomposition process of wood powder with 20%prepared nanorods and nanowires samples by using non-isothermal kinetic equation.The less weight loss by TG,the less heat release by DSC and the higher apparent activation energy of Ea indicated the better flame retardant properties.It was found that the smaller the size of the samples,the higher the flame retardancy.(3)A novel 2MgO·B2O3·1.5H2O/Mg(OH)2 nanocomposite has been controllably prepared by in-situ hydrothermal reaction,and the possible formation mechanism of the nanocomposite was proposed.As a comparison,2MgO·B2O3·1.5H2O nanobelt and Mg(OH)2 nanosheet were also prepared.All samples were characterized by XRD,FT-IR,TG,SEM,TEM and HRTEM.Furthermore,their flame retardant properties were investigated by thermal analysis method and the limiting oxygen index method,demonstrating that the flame retardancy of nanocomposite is significantly higher than that of single 2MgO·B2O3·1.5H2O or Mg(OH)2.The possible flame retarding mechanism has been proposed.It can be predicted that this nanocomposite could serve as a potential flame retardant.