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New Automotive Fabrics with Anti-odour
and Antimicrobial Properties
Saniyat Islam, Olga Troynikov, and Rajiv Padhye
School of Fashion and Textiles, RMIT University
25 Dawson Street, Brunswick VIC 3056, Melbourne, Australia
saniyat.islam@rmit.edu.au
Abstract. The aim of this research is to explore the application of bio-
polysaccharide chitosan for the purpose of incorporating fragrance oil into auto-
motive fabrics and its antimicrobial properties relevant to automotive interior
textiles. Chitosan was selected for this study for its film forming ability and inher-
ent antimicrobial attributes. 100% polyester automotive fabrics were used in this
study, as 100% polyester is predominant fibre used for automotive interior tex-
tiles. The application of microencapsulated strawberry fragrance oil was studied to
overcome the low durability issue. The microencapsulated fragrance oil was ap-
plied to the finished commercial 100% polyester automotive woven and knitted
fabrics, in combination with chitosan. The treated fabrics were then assessed for
smell retention. A new qualitative sensorial evaluation method was specifically
developed for this study. It was concluded that application of the microencapsu-
lated fragrance oil to the 100% polyester fabrics in combination with chitosan
produced durable fragrance finish. The treated fabrics were also assessed for their
antimicrobial properties. The assessment of the results indicated that the fabrics
treated with microencapsulated fragrance oil in combination with chitosan dis-
played excellent antimicrobial property. The study concluded that the use of chito-
san as a binder for the application of microencapsulated fragrance oil results in
high fragrance retention in 100% polyester automotive fabrics and also produces
excellent antimicrobial attributes in these fabrics.
1 Introduction
Recent years have seen vast evidence of research [1] in the area of finishing of
textiles to impart functional properties such as antiodour or fragrance finishing,
antimicrobial finishing, cosmeto-textiles for skin care and so on. The finishing
process of textiles is one of the main factors which determine the desired effects
for the ultimate consumer product. For automotive interiors malodour may be
generated from smoking, spillages of food items and many other external reasons
along with the microbial growth on textiles. Because automotive interior under-
goes minimal cleaning in its life span, malodour and hygiene is of great concern.
The application of fragrance in the interior fabrics will not only neutralize these
kinds of malodour but also restrict the occurring of microbial growth. It will also
82 S. Islam, O. Troynikov, and R. Padhye
give desired aromatic effects to the finished textiles. Until now limited research
has been conducted on automotive interiors for antiodour/antimicrobial or fra-
grance finishing. The present study investigates the development of 100% polyes-
ter automotive fabrics with antiodour and antimicrobial properties. To achieve this
chitosan, a biopolymer, was evaluated as a binder and also as an antimicrobial
agent. This study also evaluates the gradual or delayed fragrance release properties
of the chitosan finished fabrics and their application to automotive textiles.
Figure 1 shows the scheme of the proposed finishing of automotive textile
substrates.
Fig. 1. Schematic diagram of the finished fabric
1.1 Antiodour and Fragrance Finishing
Antiodour and fragrance finishing is a process where the substrate is subjected to
inclusion of fragrance/essential oils which gives effects such as sedation, hypno-
genesis, curing hypertension and many more. The term ‘Aromachology’ [2] was
coined in 1982 to denote the science that is dedicated to the study of the interrela-
tionship between psychology and fragrance technology to elicit a variety of spe-
cific feelings and emotions such as relaxation, exhilaration, sensuality, happiness
and well-being through odours via the stimulation of olfactory pathways in the
brain, especially the limbic system [3].A new branch of textiles called “Aro-
matherapy textiles[2,4]” involves the incorporation of these essential oils onto tex-
tile substrate for daily use.
Spraying of perfumes and airing or washing is not a permanent solution for fra-
grance incorporation, as these are temporary treatments for removal of the malo-
dour. However, incorporation of cyclodextrin or antimicrobial agents to the fabric
has been the focus of research in the past decade and is becoming more popular.
The major problem using the cage compounds such as cyclodextrin is when it
involves incorporation of fragrance compounds into textiles, because of the vola-
tile nature of the fragrances the smell dissipates after a certain time period. The
second option is the enclosure of the fragrances into micro-bubbles and release by
bursting the bubbles by external action such as abrasion or rubbing. This method
is also referred to as microencapsulation; and this technique is very popular for its
versatility in terms of application. The volatile nature of the fragrances is mini-
mized and the durability is increased by a significant margin with the process of
microencapsulation. The third possibility as shown in Table 2 involves adsorption
in porous metal oxide films, fixed as a polymer network on the fibre surface.
100% polyester fibre
Chitosan film
Entrapped microcapsules
New Automotive Fabrics with Anti-odour and Antimicrobial Properties 83
These finishes affect the quality of textiles such as softness and handle and cause
problems in downstream processes like sewing.
1.2 Chitosan as an Antimicrobial Agent
Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-
linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated
unit) [5]. Chitosan is formed commercially by deacetylation of chitin, which is the
compositional element in the exoskeleton of crustaceans such as crabs, shrimps
lobsters etc. Chitosan has three reactive groups namely primary (C-6) and secon-
dary (C-3) hydroxyl (-OH) groups and the amino-NH2 (C-2) group in each repeat
of the deacetylated unit of Chitin [6]. Thus it is poly-cationic in nature. The antim-
icrobial activity of chitosan and its derivatives has been well proven in the previ-
ous studies [7, 8, 9] but the mechanism of the antimicrobial action is yet to be dis-
covered. The acceptable interpretation is that the anionic cell surface of the
microbes interacts with the cationic chitosan causing extensive cell surface altera-
tions and damage. This leads to inhibition of the metabolism of the cell and results
in killing the cell [10]. So far it is considered that chitosan acts as a biocide for
some microbes and as biostatic in other cases.
2 Materials
100% polyester knitted 4bar warp insert Shelby fabric was used. Courses per inch
(CPI) and wales per inch (WPI) were 48 and 26 respectively. Fabric width was
145 cm and weight was 300-320 g/m2.
100% polyester woven fabric consisting yarn of 2/250 Denier in both warp and
weft was used. Ends per inch (EPI) were 83-85 and picks per inch (PPI) were 49-
51. Weight of the fabric was 280-320 g/m2.Both the knit and woven samples were
supplied by Melbatex Pty Ltd. Australia.
High molecular weight (HMW) chitosan supplied by Sigma-Aldrich Pty. Ltd,
Australia, were used for the application and used as received. The degree of
deacetylation was greater than 90% with a molecular weight of less than 3,75,000
and the viscosity was measured to be approximately 6 at 25 ºC.
RICABOND® SE series fragrance carrier microcapsules supplied by RCA
International Pty Ltd. were used in this study. Strawberry range was used for ex-
periments. Fragrance carrier microcapsules have an appearance of a thin white
opalescent emulsion with a specific gravity of 1.07 g/m3 and viscosity of 90 cPs at
25 ºC. pH of 10% solution was 4.5-5.5 and had a solid content of 48±2%.
3 Testing Method for Evaluating Smell Intensity (Smell Rating
Method)
The fragrance microcapsules entrapped by the film formed by chitosan is expected
to release the fragrance when it undergoes such instance like abrasion. In the
84 S. Islam, O. Troynikov, and R. Padhye
present study simulation of the same phenomenon was designed to evaluate the re-
lease property of fragrance microcapsules by carrying out successive abrasion cy-
cles under controlled circumstances.
Preparation of Samples
Freshly prepared solutions containing aromatic microcapsules and chitosan were
applied on polyester fabric samples by pad-dry-cure process. Chitosan concentra-
tion was varied from 0.1% to 1 %( on the weight of fabric) and fragrance carrier
microcapsule concentration was kept constant at 10 g/L. After treating, the fabric
samples were then kept in a sealed polyethylene bag. These samples were rated
10(highest smell intensity) on the rating scale. The untreated sample was rated
0(no smell) on the rating scale (Figure 2). Controlled laboratory condition of tem-
perature (20±2)0C and relative humidity (65±3) % was maintained throughout the
study.
Fig. 2. The smell-rating Scale
Procedure
The treated controlled fabric samples were subjected to a rubbing action with the
standard crock meter for 5 cycles each time for calibration of smell intensity for
the observers. The samples which were needed to be tested were also subjected to
successive abrasion cycles (10 cycles at a time for each test sample evaluated) till
the smell dissipated. After every 10 cycles the observation panel (consisted of
three people) was asked to rate and record the rating for each samples using the
smell rating scale given in Figure 2. Standard wool cloth was used as abradant and
tested sample diameter was 2.5 cm. The weight applied on the abrasion tester was
14 oz.
4 Testing Method for Determination of Smell Retention with
Abrasion
The treated fabric samples were tested for smell retention on successive abrasion
cycles using a Martindale abrasion resistance testing machine. The intensity of
smell was evaluated using the same scale described in Figure 2. Successive abra-
sion cycles were carried out for smell retention until the smell completely disap-
peared from the samples.
0 1 2 3 4 5 6 7 8 9 10
Untreated Control
New Automotive Fabrics with Anti-odour and Antimicrobial Properties 85
4.1 Antimicrobial Activity Test
The antibacterial activity was evaluated quantitatively using the modified AATCC
TM 100. K. pneumoniae (ATCC 13883), a Gram-negative bacterium commonly
found on the human body, was chosen as the test bacterium. A typical procedure
involves 1±0.1g of sample fabric, cut into small pieces of approximately 0.5×0.5
cm, was dipped into a flask containing 70 ml of sterile saline with an overnight
grown culture solution of 5 ml with a cell concentration of 7.5×105–1.5×106
CFU/ml. The flask was then shaken on a rotary wrist action shaker at 37°C for
1hour. Before and after shaking, 10µL of the test solution was extracted, serially
diluted and spread onto nutrient agar plates. After incubation at 37 C for 24 h, the
number of colonies formed on the agar plate was counted. The counting on the nu-
trient agar plates was done where the bacterial growth of only 30-300 had been
found. Percentage bacterial reduction was calculated according to the following
equation:
R = (B-A) / B × 100% (1)
Where R is the percentage bacterial reduction, B and A are the number of live bac-
terial colonies in the flask with control and treated samples after incubation.
Commercial knitted and woven were tested with the concentration of 0.3% chito-
san and 0.1% of strawberry microcapsules.
5 Results and Discussion
The treated samples were tested for film formation and subsequent entrapment of
microcapsules. Figure 3 shows Scanning Electron Micrograph (SEM) of treated
woven substrate.
Fig. 3. Woven fabric at 800 × magnifications showing the chitosan film entrapping the mi-
crocapsules
Chitosan Film
86 S. Islam, O. Troynikov, and R. Padhye
Figure 4 is plotted based on the number of abrasion cycles the smell lasted as
rated by the observer panel for each of the knitted samples to compare each con-
centration of chitosan varying from 0.1%, 0.3%, 0.5 and 1%.
Fig. 4. Comparison of concentrations of chitosan treated knitted (left) and woven (right)
samples on smell retention
For the knitted fabric samples smell lasted from 110 to 170 cycles (Figure 4).
Similar phenomenon was observed when the linear curve was plotted for the four
concentrations together. The calculated value of m (smell decay rate) from the eq-
uation y = mx+ c were 0.0955, 0.0720, 0.0556 and 0.0515 for chitosan concentra-
tion of 0.1%, 0.3%, 0.5% and 1% respectively.
The retention of smell for woven fabric maintained the similar way as for the
knitted samples except for the smell lasted from 120 to 210 cycles. This may be
attributed to the bulkiness and structure of the woven fabric. The calculated value
of m (smell decay rate) from the equation y = mx + c were 0.0871, 0.0591, 0.0539
and 0.0474 for chitosan concentration of 0.1%, 0.3%, 0.5% and 1% respectively.
In both fabrics, the trend of decrease in relative rate of decay suggests the chitosan
film was stronger with increasing concentration, which increased the durability of
smell with successive abrasion cycles. The fabric samples after abrasion experi-
ments were tested again using the SEM. The presence of the chitosan film
Fig. 5. Woven fabric at 400 × magnifications after 180 rubbing cycles
Intact Microcapsules
New Automotive Fabrics with Anti-odour and Antimicrobial Properties 87
and the microcapsules are much more visible in this picture (Figure 5). This may
be attributed to the abrasion cycles as it exposed the inner structure of the fabric
more than in the Figure 3. It can be seen that after abrasion there are still a lot of
microcapsules intact inside of the fabric structure which may need harsher condi-
tion to remove or to release.
The results of the antimicrobial test performed on the knitted and woven sam-
ples are tabulated in Table 1 and shown in Figures 6 and 7.
Table 1. Antibacterial test results for knitted and woven fabrics against K. pneumoniae
Sample Experiment number Bacteria count before
shaking
Bacteria count after
shaking Reduction in %
1 244 0 100%
2 298 0 100%
Knit
3 253 1 99.62%
1 244 1 99.62%
2 298 0 100%
Woven
4 253 0 100%
Fig. 6. Untreated and Chitosan (0.3%) treated knitted fabric showing respectively showing
large and no bacterial growth on agar plate
Fig. 7. Untreated and Chitosan (0.3%) treated woven fabric showing respectively showing
large and no bacterial growth on agar plate
88 S. Islam, O. Troynikov, and R. Padhye
The above results show that chitosan and strawberry microcapsule treated sam-
ples were very effective in killing the gram negative bacteria K. pneumoniae.
6 Discussion
In the present study HMW chitosan with molecular weight greater than 375,000
was used. High molecular weight chitosan was reported previously to have good
film forming ability and this is because of its intra and intermolecular hydrogen
bonding [11]. The micrographs taken in SEM confirm the morphological aspect of
the chitosan film as well as the presence of microcapsules containing fragrance
oil. Study[12] on chitosan films reported that the water vapour permeability of
chitosan film decreases with increased amount of concentration of chitosan. The
concentration of HMW chitosan was varied from 0.1% to 1%, keeping the micro-
encapsulated fragrance concentration of 10 gpl, to investigate the effect of differ-
ent concentration of chitosan on smell retention. The retention of the fragrance
smell that was measured by the amount of smell retained after successive abrasion
cycles was found to be higher with the increased concentration of chitosan. The
resistance to the release of the microencapsulated fragrance during the successive
abrasion is attributed to the strength of the film formed by chitosan with increas-
ing concentration. Other studies on chitosan films [13,14] reported that for the
HMW chitosan the tensile strength of the film is more and the strength of the film
increases with increasing molecular weight of chitosan. This agrees with current
study finding that HMW chitosan can form a film to entrap microcapsules onto the
fiber surface effectively and the increasing concentration of chitosan slows down
the release of the microcapsules with successive abrasion cycles. Although the
smells depleted from 100 to 210 abrasion cycles for all the samples the SEM pic-
ture (Figure 5) demonstrate that there is still a high amount of microcapsules left
inside the interstices of fabric structure. This may be due to the amount and nature
of load applied in the abrasion testing machine. The surface abrasion could only
remove the film formed on the fabric surface and hence the microcapsules which
are loosely held or just adjacent to the substrate surface were removed by abrasion
and fragrance was released. But the microcapsules which are entrapped deep in-
side the structure of the fabric with chitosan film were still intact and need harsher
conditions to release the fragrance. The retention of smell increased with increas-
ing concentration of chitosan again, suggesting the film formed by chitosan was
stronger with increase in concentration. The antimicrobial activity of the treated
samples was evaluated quantitatively. The qualitative test results show that 0.3%
HMW chitosan and 10g/L microencapsulated fragrance treated samples showed
excellent efficiency against the gram negative bacteria. This also agrees with the
previous studies [15] undertaken under similar circumstances but with cotton fab-
ric and without any aromatic microcapsules. Hence it can be seen that the straw-
berry microcapsules did not inhibit the antibacterial property of chitosan.
New Automotive Fabrics with Anti-odour and Antimicrobial Properties 89
7 Conclusion
The results demonstrated that the film formed by HMW chitosan can successfully
entrap the microencapsulated fragrance oil onto the polyester fabric surface. The
slow release property was achieved by external abrasion. For the evaluation of the
smell retention a new method was designed, developed and used for the scope of
the current study. The current study concluded that natural biopolymer chitosan
can be used successfully for the commercially available seat fabrics for fragrance
finishing and antimicrobial properties. Further studies can be undertaken to deter-
mine the minimal inhibitory concentration (MIC) of chitosan and using the gram
positive bacterial strains.
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