Comparison Between the Mechanical and Tribological Properties of Parts Manufactured by Injection Out of Polyamide Reinforced with Glass Fibres and Glass Microspheres

The use of polymeric materials to replace metal or wood has become increasingly popular lately in most fields of activity. Specific amounts of reinforcement materials have been included in the structure of these polymeric materials in order to improve their mechanical properties. The increasing popularity of these types of materials was accompanied by the development of different machinery and technologies designed to process them, so as to make them as productive as possible and to achieve inexpensive high performance parts. Natural polyamide 6.6 is a polymeric material noted for its high rigidity, hardness, impact resistance, etc. The reinforcement materials added improve the mechanical properties of this type of material. Our research consisted of a comparative study of the behavior of polyamide reinforced with glass fibers and glass microspheres when subject to different mechanical stresses. The test specimens were processed by injection and relied on an experimental Taguchi plan with six input parameters each of them with two levels. The materials employed to carry out the comparisons designed to determine the mechanical and tribological properties were natural polyamide 6.6 reinforced with 30% glass fibers and 1% furnace black, and natural polyamide 6.6 reinforced with 30% glass microspheres and 1% furnace black used to prevent microsphere agglomerations. Considering all these issues, the actual research was focused on tensile stress vs. tensile strain comparisons at 23 degrees C and 60 degrees C, and on determining the friction coefficient using disc rotation and oscillation, XRD analysis, Scanning Electron Microscopy (SEM) and EDAX analysis. As concerns tensile stresses, high values were recorded both on the 23 degrees C and 60 degrees C tests when polyamide was reinforced with glass fiber. This is also supported by the SEM structure for the two composite materials under survey. The mean value of the disc rotation friction coefficient was lower when glass fiber was used as reinforcement material. This was also the case with the disc oscillation friction coefficient. The diffraction study conducted on the two materials revealed that polyamide 6.6 reinforced with 30% glass fiber did not have an amorphous structure, given the high number of peaks resulted further to diffraction, whereas polyamide 6.6 reinforced with glass microspheres exhibited an amorphous structure and a structure-specific diffraction. The chemical elements spectrum (EDAX analysis) reveals high mass and atomic percentages of C, O, Ca for both composite materials under survey.