Research Of Both Flame-retarded Modification And Antistatic Modification Of Polyethylene

The yield of polyethylene is the biggest in the thermoplastics. Polyethylene has many distinguished features such as lightness, non-toxicity, resistance to chemical corrosion, and so on. It has been used widely in many industries such as electric industry, chemical industry, food industry, mechanical industry, and so on. Unfortunately, with low oxygen index (just 17.5), polyethylene belongs to combustible material. It is difficult to prepare flame-retarded polyethylene, because it's dripping remarkably during the burning process. Except for low oxygen index, its volume resistivity and surface resistivity are pretty high. When polyethylene has been charged, it's difficult to release the static charge. The two drawbacks of polyethylene endanger its safe use grievously. Take"safety"into consideration, flame-retarded modification and antistatic modification are needed urgently.In order to prepare both flame-retarded and antistatic polyethylene, two problems must be resolved. One is the dripping problem which has stated in detail. The other is the contradiction which exists between the flame-retarded modification and antistatic modification. Both flame-retarded and antistatic modification needs more content of flame retardants than the only flame-retarded modification, because the antistatic additives are combustion supporting materials. But massive content of flame retardants will lead to many other problems, such as poor mechanical properties, low flowing property, and so on.In recent years, non-halogen flame retardation of polyethylene has been investigated excessively. But the flame-retarded efficiency of non-halogen flame retardants is less than the halogen flame retardants. To achieve the same flame-retarded efficiency, more content of non-halogen flame retardants are needed compare to halogen flame retardants, and massive content of flame retardants will lead to other problems which were stated in detail. In this kind of situation, the new technical route that built flame-retarded system has been used to prepare flame-retarded polyethylene gradually.In this thesis, oxygen index was taken as the measurement to estimate the flame-retarded efficiency; volume resistivity and surface resistivity had been taken to estimate the antistatic efficiency after carbon fiber was added in; tensile-strength and notch impact-strength were taken as the measurements to estimate the mechanical properties. Some valuable results were discovered after tests. Firstly, flame-retarded polyethylene could not be prepared by only added APP in the polyethylene, because massive content of APP worsened the polyethylene's mechanical properties markedly. Secondly, the oxygen index of polyethylene was only 22.4, when the content of APP reached 30%, but through new technical route, flame-retarded polyethylene whose oxygen index reached 29.1 was prepared at last. Thirdly, in the foundation of flame-retarded polyethylene, many batch formulas of both flame-retarded and antistatic polyethylene had been prepared. The batch formula of J2 was chosen as the optimum formula whose oxygen index reached 27.5, volume resistivity and surface resistivity declined to 5.6×1012?·cm and 2.3×1012? respectively.In this thesis dipentaerythritol stearamide was used as the charcoal source. The contradiction between the flame-retarded modification and antistatic modification was resolved by the dipentaerythritol stearamide. Because dipentaerythritol stearamide is generally used as coupling agent or lubricant, it has very little influence on the mechanical properties of polyethylene, and it has positive influence on the processing property of polyethylene.