XPS and surface resistivity measurements of plasma‐treated LDPE and ageing effects

Abstract

Low-density polyethylene (LDPE) film containing a polydimethylsiloxane (PDMS) additive has been investigated using x-ray photoelectron spectroscopy (XPS) and surface resistivity measurements. The samples measured were: as-received; plasma-treated; washed with ethyl acetate; aged in air; and combinations of these treatments. Analysis by XPS has been used to characterize surface species concurrently with resistivity in the surface region to assist in understanding the relationship between charge transport and surface electronic structure. Radiofrequency plasma treatment causes major oxidation effects and lowering of resistivity in the first 4 s. With the same treatment time, in the case of washed samples, surface segregation of PDMS is enhanced, causing an initial increase of surface region resistivity. Plasma treatment beyond 4 s causes saturation of the O : C ratio in the surface and a loss of charged bonds. These points also allow a description of resistivity change with ageing, which includes hydration effects on exposure to air.

Optimization of adhesive joints of low density polyethylene (LDPE) composite laminates with polyolefin foam using corona discharge plasma

“…Corona discharge plasma promotes a remarkable increase in wettability of LDPE film. This is due to the action of several plasma‐acting mechanisms: surface functionalization by insertion of polar groups and changes in surface topography 26, 28, 30, 31. The overall effects of the corona discharge plasma treatment can be observed in a clear way in Figure 1 which shows the plot evolution of contact angles for different test liquids in terms of the corona discharge power.…”

“…As we can observe in Table I, a slight decrease in surface energy as the film advance rate increases can be detected as expected; nevertheless, changes in wetting properties for film advance rates from 5 to 20 m min −1 are small if compared to those derived from working power changes in the 200–600 W range. The use of film advance rates in the 5–20 m min −1 range Also, note the increase in the polar component of the solid surface energy; this is representative for surface functionalization as a consequence of surface interlock of some polar groups (mainly oxygen‐based moieties) 28, 30, 31…”

“…So, the use of a previous corona discharge plasma treatment could lead to an improvement on mechanical response of laminates together with durability of adhesive joints in hydrothermal or other aggressive conditions. On other hand we have to take into account that plasma effects are not permanent and this can induce some loss on mechanical performance 1, 2, 26–29…”

Surface characterization of silicone polymer used as an outdoor insulator by the measurement of surface voltage decay

“…The relation between surface voltage decay and surface resistivity has been studied by other researchers. 8,9 By fitting the surface voltage decay exponentially, we obtained the characteristic time constant of the voltage decay using the following expression 7 V D V 0 exp t A theoretical investigation of the surface voltage decay by surface conductivity shows that the surface resistivity s is related to the time constant of the voltage decay. 10 By considering our corona charging apparatus, we calculated the surface resistivity using the time constant for surface voltage decay.…”

Improvement in adhesive‐free adhesion by the use of electrostatic interactions between polymer chains grafted onto polyethylene plates

“…Many researchers have reported the surface modification of PE substrates through plasma treatment, glow discharge, corona discharge, UV irradiation, and so forth. [1][2][3][4] We have for more than 10 years attempted to modify hydrophobic surfaces of PE, polypropylene, and poly(tetrafluoroethylene) without changing their bulk properties by means of photografting hydrophilic monomers and to extend their possibilities to other new fields. [5][6][7] The tensile shear adhesive strength between two grafted polymer substrates has been remarkably enhanced even with low grafted amounts, and in addition, autoadhesion or adhesive-free adhesion properties were observed in a considerably high range of grafted amounts.…”