Investigation On The Preparation Of Ultrafine Surface-modified Brucite Powders And Its Application In Polyester-matrix Material

Brucite has drawn great attention as flame-retardant filler due to its high thermal stability, non-toxicity, smoke inhibition, non-volatility and lower cost. However, it is difficult to obtain sufficient interfacial bonding between matrix and brucite powders because of the poor compatibility between them. The following work has been done for trying to solve the above problems. Firstly, the ultrafine surface-modified brucite powders was prepared by mechanical milling with the planetary high-energy ball mill. Effects of the ball milling parameters and the amount of additives on the powder granularity and the modification effect were investigated. Laser Particle Size Analysis, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Activation Index, Contact Angle Measurement and Sedimentation Measurement were used to examine granularity, morphology and surface properties of the modified brucite powders. The results indicate that the D₉₀ of the surface-modified sample reduced from 32.75μm to 1.26μm. The ultrafine powders have a uniform morphology and retain the original crystal structures. The surface modification is efficient when the amount of the grinding aids is 0.2 wt.% and the amount of the surfactant is 2 wt.%. The activation index of the ball milled powders has a 98.5% increment as compared to the original powders, the contact angle increased to 131 degrees and the sedimentation time is prolonged to 22.5 hr.Secondly, Brucite / Polyester Artificial Stone was prepared by adding the ultrafine surface-modified brucite powders and consolidation additives into the unsaturated polyester resin. Effects of the types of the resins and the amount of brucite on the properties of polyester artificial stone were investigated. The flame retardancy of polyester artificial stone was measured with Limit Oxygen Index meter (LOI) and Cone Calorimeter (CONE). The LOI results indicated that the oxygen index enhanced along with the addition of brucite. It Arrives 31.3 when the portion of brucite is 50 wt.%, having been 11% enhanced compared to the pure polyester resin. The CONE analysis results demonstrated that the ignition time lengthens to 153 s and the heat release rate decreased 80%. Furthermore, the smoke production rate and total smoke production reduced by 2/3 when the polyester artificial stone contains 50 wt.% brucite. The bending strength enhanced from 27.69 MPa to 40.75 MPa, and the impact strength increased from 2.1 KJ/m^-2 to 3.1KJ/m^-2. Thirdly, the Curing Kinetics of polyester artificial stone and the polyester resin were studied by the non-isothermal DSC method. Effect of the amount of brucite on the curing properties of unsaturated polyester resin were investigated. The results showed that the curing reaction activation energy of polyester resin and polyester artificial stone are 34.5 KJ/mol and 18.1 KJ/mol, respectively. The results indicated that the brucite has inhibitory effect on the resin's curing properties.