Adhesive Property Of Polyethylene Modified By Radio Frequency Plasma Polymerization Of Ethanol Monomer

Ethanol Plasma polymer films were deposited on original polyethylene, polyethylene modified by oxygen plasma and KBr dishes, in a bell-jar-type plasma reactor with parallel plate electrodes. Deposition rate, surface morphology, chemical composition and wettability were characterized as a function of plasma polymerization parameters. The mechanism of ethanol plasma polymerization was investigated, based on the macroscopic kinetics. Ethanol plasma polymerization on untreated and pretreated polyethylene (PE) was carried out, the deposited conditions have been studied to understand the mechanism of improvement of adhesion strength.The FT-1R showed that plasma polymerized ethanol films contained hydroxyl, carbonyl and alkyl groups, the peak of epoxy stretching vibration appeared while the energy density increased. XPS results revealed that large amount of oxygen lost in the plasma polymerized ethanol films, comparing with the ethanol precursor, the C/O ratio of ethanol plasma polymer films increased from4.8to5.5while the energy density ranged from41.16J/cm3to164.64J/cm3. The morphology of ethanol plasma polymer films deposited on original PE is similar to that of original PE. having no conspicuous features. The nano-islands appeared on PE surface by200-W oxygen plasma pretreatment followed by a30minutes treatment with ethanol plasma, the aspect ratio of nano-structure increased with pretreatment time.Ethanol plasma polymer film deposited on original PE with low advancing angle (θA) of69.07°and a receding angle(θA) of54.52°while the energy density equaled to41.16J/cm3, the dynamic contact angle increased with the energy density, at the energy density of164.64J/cm3, the film had a CA of θA/θR=79.32°/60.70°. The CAs of plasma polymerized ethanol films deposited on the pretreated PE surfaces modified by oxygen plasma were characterized as a function of plasma pretreatment time, when the pretreatment time of oxygen plasma was1minute and10minutes, the film surfaces exhibited CAs of92.36°/75.5°and126.27°/114.63°at energy density of82.32J/cm3,respectively.For the thickness growth rate, a discontinuity was observed at4.3×10-4cm3/J, indicating the ethanol plasma polymerization had two different film-growth mechanisms in the range of energy density in our experiments. From4.3×10-4to1.6×10-3cm3/J, low power and high pressure located in this region, the film growth was controlled by oligomerization, and the thickness growth rate was controlled by hydrogen abstraction reaction. From1.01×10-4to4.3×10-4cm3/J. this region corresponded to higher power and lower pressure, plasma polymerization was controlled by dissociation and fragmentation, and the key to influence the deposition rate was oxygen abstraction reaction.The lap-shear strength of PE samples modified by200-W oxygen plasma pretreatment or not followed by a30minutes treatment with ethanol plasma were improved notability. A lap-shear strength of1.01MPa was obtained by a100-W ethanol plasma, one side of the fractured surfaces was polyethylene, and the other side was plasma polymerized ethanol film and epoxy resin. The lap-shear strength of2.92MPa was obtained through oxygen plasma pretreatment followed by ethanol plasma, due to the enhancement of film-substrate cohesion and increased roughness.