150 CHAPTER 5 DEVELOPMENT OF ANTIMICROBIAL PLAIN WEAVE COTTON FABRICS BY MICROENCAPSULATION AND NANOENCAPSULATION METHODS 5.1 INTRODUCTION The nano particles were synthesized, characterized, finished on cotton fabric and its antibacterial activity was assessed. Since the fabric finished with the zinc and copper nano particles did not show antibacterial activity up on washing, the nano particles were now finished by techniques in such a way to increase the durability. The techniques adopted to increase the antimicrobial activity were microencapsulation and nanoencapsulation. The zinc and copper oxide nano particles synthesized by wet chemical method were used for microencapsulation and nanoencapsulation. The methodology adopted, results obtained and the relevant figures in support of the results are presented in this session. 5.2 MICROENCAPSULATION Functional textiles are being developed in order to provide fabrics with new properties and added value. They can be obtained either by using new chemical fibers or by incorporating functional agents to conventional fabrics. Microencapsulation is an effective method to protect these functional agents from reactions with moisture, light and oxygen. The synthesized nano particles were microencapsulated by ionic gelation method using calcium
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150
CHAPTER 5
DEVELOPMENT OF ANTIMICROBIAL PLAIN WEAVE
COTTON FABRICS BY MICROENCAPSULATION AND
NANOENCAPSULATION METHODS
5.1 INTRODUCTION
The nano particles were synthesized, characterized, finished on
cotton fabric and its antibacterial activity was assessed. Since the fabric
finished with the zinc and copper nano particles did not show antibacterial
activity up on washing, the nano particles were now finished by techniques in
such a way to increase the durability. The techniques adopted to increase the
antimicrobial activity were microencapsulation and nanoencapsulation. The
zinc and copper oxide nano particles synthesized by wet chemical method
were used for microencapsulation and nanoencapsulation. The methodology
adopted, results obtained and the relevant figures in support of the results are
presented in this session.
5.2 MICROENCAPSULATION
Functional textiles are being developed in order to provide fabrics
with new properties and added value. They can be obtained either by using
new chemical fibers or by incorporating functional agents to conventional
fabrics. Microencapsulation is an effective method to protect these functional
agents from reactions with moisture, light and oxygen. The synthesized nano
particles were microencapsulated by ionic gelation method using calcium
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alginate as the wall material. The nano particle solution was mixed with
sodium alginate and sprayed into calcium chloride solution. The capsules
were then retained in calcium chloride solution and then washed with iso
propyl alcohol and then dried. The dried microcapsules were then used for
finishing the cotton fabrics.
5.2.1 Microscopic Examination of the Microcapsules
The synthesized microcapsules were viewed under light microscope
at 400 X magnification to determine the structure of the capsules. The
following figure 5.1shows the microscopic view of the microcapsules
synthesized from the nano particles.
Figure 5.1 Microscopic view of microcapsules (400 X magnification)
From the above figure, it was clear the microcapsules were of
uniform size and shape. These microcapsules were then applied on the fabric
by exhaustion method and tested for their properties.
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5.2.2 Finishing of Plain Cotton Fabric with Microcapsules
The dried nano zinc and copper oxide microcapsules were finished
on the fabric by exhaustion method. During the finishing process, 8% citric
acid was used as binder to firmly fix the microcapsules on the fabric. The
microcapsule-finished fabrics were tested for their properties and compared
with that of the nanocapsules finished fabrics.
5.3 NANOENCAPSULATION
The nano particles were nanoencapsulated using bovine serum
albumin as the wall material and inside these capsules; the nano particles are
trapped to exert their properties strongly. The nanocapsules so produced were
applied on the fabric by exhaustion method. The finished fabrics were tested
for their properties using standard methods.
5.3.1 Nanoencapsulation
The nanocapsules were prepared by coacervation process using
protein solution and cross-linked using glutaraldehyde. The organic solvent
was removed under reduced pressure by rotary vacuum evaporator and the
nanocapsules obtained were centrifuged for purification. The nanocapsules
obtained were further dried by lyophilisation and they were applied on the
cotton fabric by exhaustion method using 8% citric acid as binder.
Figure 5.2 Nanocapsules of copper oxide nanoparticles
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5.4 COMPARISON OF MICROCAPSULE FINISHED FABRIC
WITH NANOCAPSULE FINISHED FABRIC
The microcapsules and nanocapsules finished fabrics were dried
and they were subjected to various functional and physical testing in order to
determine the efficiency of the encapsulation methods. The properties of the
finished fabrics such as antibacterial activity, Fourier transform infrared
spectroscopic analysis, scanning electron microscopic analysis were
performed and the results are presented below.
5.4.1 Antibacterial Activity Assessment
The antibacterial activities of the capsule finished fabrics were
assayed by AATCC 147 test method against both Staphylococcus aureus and
Escherichia coli organisms. The results of the antibacterial activities are
presented in Table 5.1 and Figures 5.2 to 5.5.
Table 5.1 Antibacterial activity of capsules finished cotton fabric
S. No. Type of sample
Antibacterial activity
(Zone of Bacteriostasis – mm)
Escherichia
coli
Staphylococcus
aureus
1Copper oxide nano particles
Microencapsulated fabric29 33
2Zinc oxide nano particles
Microencapsulated fabric28 29
3Copper oxide nano particles
nanoencapsulated fabric30 34
4Zinc oxide nano particles
nanoencapsulated fabric27 30
From the above table, it was found that the antibacterial activity
was maximum for copper oxide nano particles nanoencapsulated fabric
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against Staphylococcus aureus followed by microcapsules finished fabric.
Both the nanocapsules and microcapsules finished fabrics showed lesser
reduction against Escherichia coli.
Staphylococcus aureus Escherichia coli
Figure 5.3 Antibacterial activity for plain weave cotton fabric finished
with nano copper oxide microcapsules
Staphylococcus aureus Escherichia coli
Figure 5.4 Antibacterial activity for plain weave cotton fabric finished
with nano zinc oxide microcapsules
155
Staphylococcus aureus Escherichia coli
Figure 5.5 Antibacterial activities for plain weave cotton fabric finished
with nano copper oxide nanocapsules
Staphylococcus aureus Escherichia coli
Figure 5.6 Antibacterial activities for plain weave cotton fabric finished
with nano zinc oxide microcapsules
The AATCC 147 test method performed on the plain weave cotton
fabric finished with the copper oxide microcapsules and nanocapsules showed
156
excellent results when compared with zinc oxide microcapsules and
nanocapsules finished fabrics.
5.4.2 Fourier Transform Infra Red Spectroscopic Analysis
As the results of the research provided valid evidence favouring
copper oxide microcapsules and nanocapsules finished fabrics, further
research involving FTIR analysis, SEM and other technical specification were
concentrated only for copper oxide microcapsules and nanocapsules coated
fabrics and are shown in figure 5.6 and 5.7.
Figure 5.7 Fourier transform infrared spectrogram of microcapsule
finished plain weave cotton fabric
The fourier transform infrared spectroscopic analysis of the cotton
fabrics shows peaks corresponding to the regions of wavelength 559.77,