Thesis-1992-Sheng.pdf (6.22 MB)
Surface modification of polypropylene to improve its adhesion
thesis
posted on 2012-11-28, 14:29 authored by Enshan ShengSurface modification of a propylene homopolymer, an ethylene / propylene
copolymer, and a rubber-modified polypropylene (PP) has been studied using
X-ray photoelectron spectroscopy (XPS), chemical derivatisation, contact
angle measurement, scanning electron microscopy (SEM), and an adhesion
test. The wettability of PP surfaces was found to have been improved by
solvent treatment. Mild adhesion level was obtained using solvent vapour
treatment. Chromic acid etching and priming were found effective in
improving the adhesion of PP. Flame treatment was found to give excellent
adhesion. Optimum air-to-gas ratio and the distance from the inner cone tip
of the flame to the polymer surface were found to be -11:1 and 0.5-1.0 cm
respectively. The non-correspondence between oxygen concentration and
contact angle at high oxygen concentrations was attributed to sub-surface
oxidation and the orientation / migration of oxygen containing functional
groups away from the near surface during the flame treatment. This
hypothesis was supported by angle resolved XPS results. The use of simple
surface composition models has shown that the oxidation depth induced by a
mild flame treatment is between 40A and 60A, and that oxygen containing
functional groups may have orientated or migrated a few angstroms away
from the near surface for an intense flame treatment. Trifluoroacetic
anhydride (TFAA) has been found to be a good derivatising reagent for
hydroxyl groups. About 20% of the oxygen present on the surface of flame
treated propylene homopolymer was found to be present as hydroxyl groups,
while a slightly. higher percentage (-30%) was found for the two copolymers.
While hydroxyl groups were found unimportant in the adhesion with an
epoxy adhesive, they were found important, but not essential, in the
adhesion with a polyurethane paint.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Materials
Publisher
© Enshan ShengPublication date
1992Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en