Polycarbonate (PC) thermoplastic engineering plastic is a comprehensive performance material with outstanding impact resistance and dimensional stability, as well as high heat resistance and cold resistance, and is known as a transparent metal. This product is widely used in technical fields such as electronic appliances, automobiles, machinery manufacturing, aerospace, computers and optical discs.
However, the surface of PC material has poor scratch resistance, which greatly reduces the aesthetics of the product. In addition, scratches on the product surface can also cause stress concentration. In order to improve the scratch resistance of PC, the experiment used different mass fractions of silicon to modify the scratch resistance of PC. Through the characterization and experimental analysis of its modification properties, the scratch resistance of PC+5% whisker silicon has been improved to a certain extent. Its pencil test hardness is H, and the modified PC system has good overall performance. However, in areas where product surface performance is required, such as the casings of electronic products such as mobile phones, PC applications are still higher.
Experimental part
1. Raw materials and reagents
PC31010 polycarbonate
whisker silicon: chemically pure
silicone powder: chemically pure
coupling agent: KH550, chemical purification
2. Equipment and instruments
High-speed mixer: GH-10DY
twin-screw extruder: Plasti’Corder type
flat plate vulcanizing machine: OLB.25D/Q type
Through experiments, the impact of different silicone powder dosages on the tensile properties and notched impact strength of the modified PC system will change. As the dosage of silicone powder increases, the tensile strength of PC gradually increases, and the notched impact strength increases slightly, but the improvement effect is not obvious, but the elongation at break decreases. This is because silicone powder is composed of ultra-high molar mass siloxane, and its main molecular chain contains Si. -O-Si bond, strong intermolecular force, and contains inorganic rigid particles with an average particle size of 5/zm. It has good dispersion effect with resin and good lubricity of silicone powder. When added to the modified PC system, it can be mixed evenly with the modified PC system, with strong interaction and good enhancement effect. Therefore, the tensile strength of the modified PC system is improved, and the melt quality and flow rate of the PC system are significantly improved.
As the dosage of silicone powder increases, the tensile strength, melt quality and flow speed of the modified PC system increase, the impact strength of the notch remains basically unchanged, the elongation at break decreases, the non-Newtonianity of the melt weakens, and the modified PC system The scratch resistance of the PC system is better, the pencil hardness is 2H, when the anti-scratch agent mass fraction is 1.2%.
Therefore, the modified formula of the modified PC system is: PC + 5% whisker silicon + 1%. At this time, the thermal deformation temperature of the modified system is 133.8qC, the tensile strength is 69.04MPa, and the elongation at break is 6.94%. , the notched impact strength is 10.11kJ/, the melt mass flow rate is 45.81g/10min, and the pencil hardness is 2H.
