Study On The Metal Oxides Modification Of PTFE As Thermoplastic Adhesive

On the basis of the general analysis of Teflon, referring to the domestic and foreign relating technologies, the metal oxides are studied to modify PTFE as a thermoplastic resin. Thermal property,Shore hardness, frictional behavior and compressive strength were tested and the effect of different filler, filler content are therefore concluded. The influences of mixing and moulding technologies on PTFE mechanical properties and thermal property were investigated as well. The crystalline structure, microstructure, components of samples were characterized with X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray Energy Dispersive Spectrometer (EDS). The feasible modification mechanisms are proposed.Experimental results show that: PTFE composites filled with nano-zinc oxide have better thermal performance and mechanical properties than those of pure PTFE. The comprehensive performance are the best with the 5% contents of zinc oxide. The melting point (Tm) of PTFE composites increases with the increasing amount of Nano-zinc oxide to 5 wt % and then declines. The highest Tm is 337.8°C which is higher 2.6°C than pure PTFE with the 5 wt % contents of nano-zinc oxide. The variations of friction properties and compressive strength of modified composites are similar to the above. The minimum wear quantity (0.1941g) and the biggest compressive strength (45.39 MPa) also appear at the sample with 5 wt % of nano-zinc oxide. The highest hardness (32.58 kg/mm2) shows up at the sample with 3 wt % nano-zinc oxide and then declines with the increasing of nano-particles.To some degrees, PTFE resin filled with lead oxide and copper oxide deonstrates similiar hardness and anti-friction properties as modified by Nano-zinc oxide, but worse compressive strength and thermal performance. According to orthogonal test results, the best comprehensive performance appears at the sample of PTFE modified by PbO 4 wt %, CuO 5 wt %, the mixing time of 60 min and molding pressure of 20t. Tm of the sample is 324.7°C, the hardness 30.81 kg/mm2, wear quantity 0.1187 g and compressive strength 28.15 MPa.There is a compatibility between the filler and PTFE matrix, which depends on the size of the filler, the amount of filler and the filler's nature properties. When the filler size is big and its distribution is uneven, the connection between the filler and PTFE becomes worse,and therefore the nano modification takes advantages in improving thermal performance of PTFE. When the content of filler is less than an optimum or over the limit or the filler has not self-lubrication ability, PTFE still shows adhesive wear as usual or changes into fatigure wear, which both diminish the modification effects.