Extreme durability of wettability changes on polyolefin surfaces by atmospheric pressure plasma torch

Abstract

Institutional RepositoryThis is a postprint version of the following published document: In the present work three common polyolefins: high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP) have been treated with an atmospheric pressure air plasma torch (APPT) in order to improve their wettability properties. The variations in surface energy (γ s ), as well as the durability of the treatment are determined by means of contact angle measurements for different aging times after plasma exposure (up to 270 days) using five test liquids which cover a wide range of polarities. The introduction of new polar moieties (carbonyl, amine or hydroxyl) is confirmed by Fourier transform infrared spectroscopy in attenuated total multiple reflection mode (ATR FTIR) and X ray photoelectron spectroscopy (XPS). Furthermore, scanning electron microscopy (SEM) provides information on the morphological changes and variation on surface roughness, revealing that smoother, lamellar and semispheric micrometric structures are created on the LDPE, HDPE and PP surfaces, respectively. Results show that APPT treatment enhances both the total and polar components of the γ s under study, with an unprecedent stability (N 8 months) in time.

Development of improved polypropylene adhesive bonding by abrasion and atmospheric plasma surface modifications

“…After abrading, an exhaus tive cleaning step was necessary due to the amount of detached particles from the sandpaper generated in the process. Plasma treatment was achieved using an APPT set up, described in detail elsewhere [23]. Briefly, the air plasma species were generated by a non equilibrium high tension discharge of 20 kV at a frequency of 17 kHz and expelled through a rotating torch situated at 6 mm distance to the samples.…”

“…The devices are described elsewhere [23], but briefly, they consist of a VG Scientific Microtech Multilab (VG Scientia, Hastings, United Kingdom) spec trometer using a Mg K a X ray source (1253.6 eV) and a Brucker Tensor 27 (Brucker Optik GmbH, Madrid, Spain) spectrometer.…”

Optimization of atmospheric plasma treatment of LDPE films: influence on adhesive properties and ageing behavior

“…The Owens-Wendt is able to determine both additive contributions of the γ s , dispersive (due to London type forces) and polar (which accounts for the dipole-dipole and hydrogen bonding interactions 21 . The expression that graphically represents an equation in y= a + bx form is the following:…”

“…For the purpose of finding the best conditions of treatment, six conditions of treatment have been studied according to previous studies, concretely 6 and 10 mm for sample distances and 100, 300 and 700 mm·s -1 for treatment rates. 21 .…”

“…Moreover the ageing in a non-polar environment force to the polar groups to recombinate or to react with functional groups of the environment. Both the rearrangement of oxygen-containing moieties such as the reorientation of polar groups from surface to bulk lead hydrophylicity to decrease 21 .…”