Study On The Application Of Low Temperature Plasma In The Degradation Of Polyethylene

In recent years,low-temperature plasma technology has attracted wide interest due to its application in the fields of environment,materials,chemical industry,energy,agriculture,biomedicine and other fields.Low temperature plasma can promote many physical and chemical reactions at room temperature due to its characteristics of a large number of highenergy active particles at room temperature.In this paper,using the excellent characteristics of low temperature plasma,the research direction of using low temperature plasma to degrade polyethylene plastics was proposed.A series of experiments are used to select the plasma working conditions and liquid phase environment for effectively degrading polyethylene.Treat the mixture of polyethylene and n-octane,and the effects of different voltage gradients were studied.(1)The basic characteristics such as voltage,current and spectrum of plasma discharge were detected.By analyzing the plasma discharge spectrum,the discharge process is divided into two stages,the first is to discharge in the pre-introduced protective gas.With the gradual decomposition of polyethylene and solvent during the discharge process,the gas product replaces the protective gas,and the second stage of discharge occurs in the product gas.(2)The effect of discharge plasma degradation of polyethylene under different conditions was studied.For different working gases such as air,air plus water vapor,and n-octane as the liquid phase environment in the air plus water vapor,etc.,plasma treatment polyethylene experiment was carried out,the infrared spectrum of the experimental product was measured,and the temperature and quality during the experiment were measured.It was found that the use of n-octane as the liquid phase environment can greatly improve the degradation effect of plasma on polyethylene,and a suitable protective gas can also promote the degradation reaction of polyethylene.This part provides a basis for further research on the influencing factors of plasma degradation of polyethylene.(3)The solid phase products,liquid phase products and gas phase products of plasma degradation of polyethylene was explored.Plasma treatment of polyethylene at an AC voltage of 10 k Hz and above 40 k V has a significant effect.As the voltage amplitude increased,the mass and molecular weight of the solid phase product decreased;when the voltage in the liquid phase product was lower,longer short-chain alkanes and olefins were generated,the number of carbons in the molecule was greater,and the voltage was lower.When it was high,the short chain length is shortened;in the gas product,as the voltage increased,the proportion of lowcarbon molecules increased,but the proportion of hydrogen did not change much.This part provides support for verifying the effectiveness and influencing factors of plasma degradation of polyethylene.(4)The influence of the catalyst on the degradation effect was studied.The catalyst was added to the reaction,the polyethylene was treated with plasma under different voltage amplitude conditions,the solid phase product,the liquid phase product and the gas phase product were detected and compared with the results without the catalyst.Under the effect of adding catalyst,the degradation reaction of polyethylene can achieve the effect of not adding catalyst at a lower voltage bar,which shows that the molecular weight and mass of the solid product are less under the same voltage amplitude,and the organic matter length of the liquid product was shorter;After adding the catalyst,the proportion of hydrogen in the gas-phase products had been greatly improved,and the proportion of hydrogen with the voltage change was still not obvious.Combined with the experimental results,it provides a reference for exploring the effect of catalysts on plasma degradation of polyethylene and subsequent improvements.