applied surface science Applied Surface Science 72 (1993) 143-147 North-Holland UV ozone modification of wool fibre surfaces R.H. Bradley *, I.L. Clackson and D.E. Sykes Institute of Surface Science and Technology, University of Technology, Loughborough, Leicestershire, LEll 3TU, UK Received 21 February 1993; accepted for publication 2 June 1993 An ultraviolet (UV) ozone treatment has been used to oxidise t he surfaces of batches of natural wool fibres. The changes in surface composition and chemistry induced by this treatment have been followed using X-ray photoelectron spectroscopy (XPS). Oxidation of surface di-sulphide sulphur to sulphonic acid groups (-SO,H) containing S 6+ is observed at levels of approxi- mately 90% conversion. This is significantly higher than levels previously achieved using oxygen plasmas. The treatment also appears to cause reaction of the proteinaceous carbon, leading to an increase in carbon-oxygen, particularly carbonyl, functional- ity. The data presented indicate that the treatment used is capable of producing surface sulphur and carbon chemistry of the type usually obtained by wet chlorination. 1. Introduction The commercial shrink proofing of natura l wool is normally carried out by the deposition, from solution, of cationic polymers such as epichlorohydrin polyamide (known commercially as Hercosett). The successful adsorption of such polymers requires a surface oxidative pre-treat- ment which increases the surface polarity of the wool fibres by the introduction of anionic func- tional groups. This is usually done using solutio ns of chlorinated compounds which oxidise sulphur, present in the di-sulphi de linkages -S-S- of the protein structure, to S6+ in the form of sulphonic acid groups -SO,H. This process gives effectively 100% oxidation of the S2+ [1,2] but produces large quantities of chlorinated waste water. It is therefore desirable to identify alternative effluent free treatments on environmental grounds. In previous work [3] we have shown that oxy- gen plasma treatment can be used to increase the levels of surface oxygen present in natural wool fibres from N 10 to N 20 at%, this latter level being commensurate with that achieved by com- plete oxida tion of di-sulphi de linkages by the wet * To whom correspondence should be addressed. chlorination technique presently used commer- cially. However, when oxygen plasmas are used results indicate that only about 30% o f this oxy- gen increase is due to the oxidation of di-sulphid e to sulphonic acid sulphur w hilst the remainder is attribu table to oxidation of surface proteinaceous carbon which leads to the formation of hydroxyl/ ether (C-O) and carbon yl (C=O) functionali ties. In this paper we report the use of a UV ozone treatment for the oxidation of natural wool fibre surfaces. XPS has been used to characteri se the changes in surface c omposition and chemistry. This technique is firmly establi shed for surface chemical studies of this type [l] and is shown here to give quantitative information reflecting the ef- fects of fibre oxidation. Data are presented which indicate modification of both surface sulp hur and carbon species. 2. Experimental details 2.1. Samples Results are presented for untreated natural wool fibre surfaces and for similar surfaces after exposure to UV ozone. For treatment , natura l 0169-4332/93/$06.00 0 1993 - Elsevier Science Publi shers B.V. All rights reserved
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
8/3/2019 UV Ozone Modification of Wool Fibre Surfaces
Institute of Surface Science and Technology, University of Technology, Loughborough, Leicestershire, LEll 3TU, UK
Received 21 February 1993; accepted for publication 2 June 1993
An ultraviolet (UV) ozone treatment has been used to oxidise the surfaces of batches of natural wool fibres. The changes in
surface composition and chemistry induced by this treatment have been followed using X-ray photoelectron spectroscopy (XPS).Oxidation of surface di-sulphide sulphur to sulphonic acid groups (-SO,H) containing S6+ is observed at levels of approxi-
mately 90% conversion. This is significantly higher than levels previously achieved using oxygen plasmas. The treatment also
appears to cause reaction of the proteinaceous carbon, leading to an increase in carbon-oxygen, particularly carbonyl, functional-
ity. The data presented indicate that the treatment used is capable of producing surface sulphur and carbon chemistry of the type
usually obtained by wet chlorination.
1. Introduction
The commercial shrink proofing of natural
wool is normally carried out by the deposition,
from solution, of cationic polymers such as
epichlorohydrin polyamide (known commercially
as Hercosett). The successful adsorption of such
polymers requires a surface oxidative pre-treat-
ment which increases the surface polarity of the
wool fibres by the introduction of anionic func-
tional groups. This is usually done using solutions
of chlorinated compounds which oxidise sulphur,
present in the di-sulphide linkages -S-S- of the
protein structure, to S6+ in the form of sulphonic
acid groups -SO,H. This process gives effectively
100% oxidation of the S2+ [1,2] but produces
large quantities of chlorinated waste water. It istherefore desirable to identify alternative effluent
free treatments on environmental grounds.
In previous work [3] we have shown that oxy-
gen plasma treatment can be used to increase the
levels of surface oxygen present in natural wool
fibres from N 10 to N 20 at%, this latter level
being commensurate with that achieved by com-
plete oxidation of di-sulphide linkages by the wet
* To whom correspondence should be addressed.
chlorination technique presently used commer-
cially. However, when oxygen plasmas are used
results indicate that only about 30% of this oxy-
gen increase is due to the oxidation of di-sulphide
to sulphonic acid sulphur whilst the remainder is
attributable to oxidation of surface proteinaceous
carbon which leads to the formation of hydroxyl/
ether (C-O) and carbonyl (C=O) functionalities.
In this paper we report the use of a UV ozone
treatment for the oxidation of natural wool fibre
surfaces. XPS has been used to characterise the
changes in surface composition and chemistry.
This technique is firmly established for surface
chemical studies of this type [l] and is shown here
to give quantitative information reflecting the ef-
fects of fibre oxidation. Data are presented which
indicate modification of both surface sulphur andcarbon species.
2. Experimental details
2.1. Samples
Results are presented for untreated natural
wool fibre surfaces and for similar surfaces after
exposure to UV ozone. For treatment, natural
0169-4332/93/$06.00 0 1993 - Elsevier Science Publishers B.V. All rights reserved
8/3/2019 UV Ozone Modification of Wool Fibre Surfaces