Study On The Thermodynamic Performance And Frictional Heat Behavior Of Metallic Oxides/ Polyamide 1010 Composites

The thermodynamic properties of the micron metallic oxides (ZnO, CuO, Fe3O4) inorganic filler modified polymer-based composites and the thermal effects of composites caused by sliding friction are choused as the major research directions. Through injection molding by melt blending, metallic oxides / polyamide 1010 (PA1010) composites has been prepared. In different conditions, the influents of variety of experimental parameters on the thermodynamic properties of polyamide 1010 and its metallic oxide / polyamide 1010 composites are investigated systematically. Besides, the disc type comprehensive testing machine which can change speed for measuring frictional heat is designed independently to analyses the surface temperature field and frictional properties of metallic oxides / polyamide composites. The following experimental results are obtained.1. The thermal conductivity of metallic oxides / polyamide 1010 composites not only improves with the increase of metallic oxides content, but also relates to the filler particle size, temperature, the preparation process of composites materials. The analysis's results show that composites thermal conductivity changing curve determined by experimental is located in between Y.Agari series model curve and parallel curve, closer to Y.Agari series model, while the temperature dependence of composites'heat expansion coefficient obeys Metrical Nai-Sen law.2. Static mechanical experiments and dynamic mechanical analysis (DMA) indicate that Compared with polyamide 1010, the mechanical properties of metallic oxides / polyamide 1010 composites have been improved significantly, while there is a peak with the increase of metallic oxides content. Limit mechanical performance prediction model is constructed to estimate the ultimate compressive strength based on storage modulus at a certain temperature range and the measured results certificate this method is feasible. Dynamic mechanical properties of metallic oxides / polyamide 1010 are discussed in different aging degree. The results show that when aging began, the loss factor of ZnO / PA1010 composites have less change within 70 days but greater change after 70 days.3. Under the different working conditions, sliding friction heating experiments of metallic oxides / polyamide 1010 composites were conducted on the comprehensive testing machine. Surface temperature distribution characteristics of the composites are generalized. The maximum temperature is in the center, while the minimum is around the outer borderline. Greater change .besides, the Surface temperature gradient has greater change along the radial, but less change around the circumferential. Compared with the polyamide 1010, the surface temperature rises of the composites increase with the addition of the metallic oxides content. The frictional factor of polyamide 1010 increase gradually with frictional time under the low-speed, while go up at first then stabilize under the high-speed. When the frictional temperature is less than Tg of composites, the frictional coefficient increases with the rise of temperature. On the contrary it drops sharply.4. Experimental data demonstrate that the speed will intensify the wear of polyamide 1010 composites. By exploring the picture of frictional surface transfer film, it can be revealed that the transfer film will go through generation (not continuous), growth (multi-layer stack), maturity (uniform, dense) and damage (melting) four phases with the rising of speed. Under the higher stress, not only do the mechanical properties of polyamide 1010 matrix decrease as the accumulation of frictional heat but also transfer film is difficult to be formed and contain. Owing to these two factors, the wear rate is much higher.5. For the bottleneck existing in the 3D transient temperature field research on polymer composites friction disk, "Disc type brake" transient temperature field is simulated with thermal analysis module of finite element analysis in ANSYS. At the boundary conditions, considering the change of heat flux along the radial and the forced heat exchanger of air etc, the law of 3D transient temperature and temperature gradient distribution are obtained under the uniform and brake conditions. The Studies have shown that it agree well with the experimental results.