The Investigation Of Polymer Surface Modification By Cold Plasma Treatment And Grafting Polymerization

This paper reports the influence of cold plasma treatment to the mass loss ratio and surface chemical structure of polymer, and the polymer surface modification by plasma-induced grafting polymerization.First, this paper studied the surface modification of argon plasma to polyethylene, and analyzed the mechanism of Ar plasma affect the polymer surface by using ATR-FTIR. analysis. The mass loss ratio has maximum value at discharge time of 70-120 seconds or discharge power of 62W by using argon plasma treatment for polyethylene. New surface structure was formed after polyethylene was treated by argon plasma. The peroxide bond peak area also has maximum value at discharge time of 70-120 seconds or discharge power of 62W. The C=C nonsaturated double bond absorb peaks were appeared at 1640cm^-1, 1549cm^-1 and 1528cm^-1 after polyethylene treated by argon plasma. The C=C nonsaturated double bond absorb peak area has minimum value at discharge time of 60-70 seconds and the power of 65W. The C=C nonsaturated double bond absorb peak area has maximum value at discharge power of 62-72W and the discharge time of 120 seconds. The absorption peak intensity of 2916cm^-1 methylene nonsymmetry stretch vibration, 2848cm^-1 methylene symmetry stretch vibration, 1463 cm^-1 methylene nonsymmetry changing angle vibration, and 719 cm^-1 methylene swing in plane vibration was decreased greatly. The four absorption peaks intensity has maximum value at discharge time of 120 seconds or discharge power of 62W.Second, this paper studied the surface modification of nitrogen plasma to polyethylene, and analyzed the mechanism of nitrogen plasma affect the polymer surface by using ATR-FTIR and AFM analysis. The mass loss ratio increases along with the increasing of discharge time, and has maximum value at discharge time of 30 seconds, minimum value at 60 seconds, keeping constant at 120-480 seconds by using nitrogen plasma treatment for polyethylene. This is because of the different mechanism of etching and grafting in different region for nitrogen plasma treatment. New surface structure was formed after polyethylene was treated by nitrogen plasma. The peroxide bond peak area is small at discharge time of 90-210 seconds, and has maximum value at discharge time of 300 seconds. The C=C nonsaturated double bond absorb peaks were appeared at 1630cm^-1 and 1550cm^-1 after polyethylene treated by nitrogen plasma. The C=C nonsaturated double bond absorb peak area has maximum value at discharge time of 30 seconds, minimum value at 60-120 seconds, maximum value at 300 seconds. The absorption peak intensity of 2916cm^-1 methylene nonsymmetry stretch vibration, 2848cm^-1 methylene symmetry stretch vibration, 1463 cm^-1 methylene nonsymmetry changing angle vibration, and 719 cm^-1 methylene swing in plane vibration was decreased greatly. The influence effect of the four absorption peaks intensity is the same as that of mass loss ratio with discharge time and power. The NO₂ and C—N stretch vibration absorb peaks were appeared at 1340cm^-1 and 1270cm^-1 after polyethylene treated by nitrogen plasma, respectively. The NO₂ and C—N bond absorb peak area has maximum value at discharge time of 30 seconds, minimum value at 90 seconds, maximum value at 300 seconds. The changing rule of mass loss ratio versus argon plasma discharge power is that the mass loss ratio has maximum value at discharge power of 35W, and minimum value at 75W. The influence effect of peroxide bond, C=C nonsaturated double bond, NO₂ and C—N bond absorb peak area is the same as that of mass loss ratio with discharge power.In addition, this paper studied the surface modification of polymer by plasma-induced polymerization method. It was confirmed that monomers contain double bond were grafted on the polymer surface by ATR-FTIR analysis when using PE as polymer substrate, methyl acrylic acid (MAA) as monomer. The influence of grafting reaction condition to the grafting degree was also investigated. The higher the reaction temperature was, the higher the grafting degree was. The grafting degree increased sharply when the reaction temperature reached boiling temperature of the reaction solution. The grafting degree was proportion increasing with the reaction time. The higher the monomer concentration was, the higher the grafting degree was. The solvent had great influence to the grafting reaction. The grafting degree increased linearly with the increasing of volume ratio R(R=V_H2O/V_cnH2n+1OH) when using alcohol and water as mixed solvent. When R was zero, that is to say, only using alcohol as the solvent, the grafting degree were zero for PE grafting MAA. When R was the same, the grafting degree had the following changing trend.PE-g-MAA:(isopropyl alcohol + water) >(methanol + water) >(ethanol + water)...