Imparting antimicrobial and fragrance finish on cotton using chitosan with silicon softener

Transcription

1 Indian Journal of Fibre & Textile Research Vol. 32, March 2007, pp Imparting antimicrobial and fragrance finish on cotton using chitosan with silicon softener Anjali Karolia a & Snehal Mendapara Department of Clothing and Textiles, Faculty of Home Science, The M S University of Baroda, Vadodara , India Revised received 2 January 2006; accepted 12 May 2006 Chitosan has been used in combination with citric acid and silicon softener to impart antimicrobial and fragrance finish with two different application techniques. It is observed that the finish provides better functionality to the fabric as it shows good performance and improvement in physical properties. The finish shows good fastness to washing as well as perspiration. The use of carboxylic acid also improves the affinity of chitosan for cellulose. Keywords: Antimicrobial finish, Chitosan, Fragrance finish, Microencapsulation, Silicon softner IPC Code: Int.Cl. 8 A61K9/70, D06M13/00 1 Introduction Necessity to meet the growing demand of consumers led to the revolution in functional finishes worldwide. Cotton is widely used for apparel due to its comfort property, but it has two main drawbacks, susceptibility to creasing and bacterial degradation. Human sweat provides a suitable shelter for bacterial growth, containing 1.4 million bacteria per gram which increases to 9000 million at 50% moisture level. 1 Chemical compounds are used as antimicrobial agents but they also influence the natural flora of the human skin. Studies have shown that chitosan, a natural biopolymer, is antibacterial, antifungal, antiviral, non-toxic, non-allergic and biocompatible. 2 Microencapsulation provides a mean of packaging, separating and storing materials on a microscopic scale for triggered release under controlled conditions, such as mechanical rupture, electrical or chemical means or by leaching action in an appropriate liquid environment. Core substances may be perfumes, any healthcare active ingredients or even liquid crystal and solid one. Microencapsulation offers many advantages as compared to conventional processes, in terms of economy, energy saving, eco-friendliness and controlled release of substance. Fragrances which are volatile and susceptible to oxidation and escaping from finished product can be readily preserved with a To whom all the correspondence should be addressed. anjalikarolia@hotmail.com specialty starch encapsules, like β-cylodextrin, petrolatum and various silicon-based materials. Aly et al. 3 observed that chitosan citrate imparts higher wrinkle recovery and antimicrobial properties to the fabric as compared to chitosan alone. It is also revealed that silicon softener causes higher encapsulation of fragrance than cationic and non-ionic softeners and improves the wrinkle recovery of the fabric. 4 Therefore, the present work was carried out with an objective to study the effect of silicon softener and chitosan with lavender fragrance on certain physical and performance properties of cotton fabric. The effect of application techniques on the fabric properties was also studied. 2 Materials and Methods Scoured 100% cotton poplin was used for the study. Silicon softener procured from Bistacel Silicon Ltd, Mumbai, and Chitosan procured from Mahtani Chitosan Ltd, Veraval, were used. 2.1 Application of Finish, Fragrance and Perspiration Treatment Application of finish was done in a one -bath process using padding as well as exhausting method as per the recipe given in Table 1. Chitosan (2-aminoß-1-4-glucose polymer) with a molecular formula (C 6 H 11 O 4 N) n was dissolved in 1% acetic acid solution and soaked overnight to make a homogeneous mixture. The degree of deacetylation was 98% and viscosity was 1200cps in 1% acetic acid solution. The fabric was then padded with the prepared recipe using a padding mangle (1dip 6nip) at a pressure of 2.3 kg/ cm 2

2 100 INDIAN J. FIBRE TEXT. RES., MARCH 2007 Table 1 Recipe for finish application [Material-to-liquor ratio 1:5 (Padding) and 1:30 (Exhaustion)] Finishing agent Conc. of finishing agents, % Padding Exhaustion Silicon softener Citric Acid 10 6 Na 2 HPO Chitosan to obtain an add- on of 8.2%. The fabric was also prepared by the exhaust method in which it was treated in the prepared bath for 45 min at 80 C, and an add- on of 9.6% was obtained. this treatment, 10% fragrance was applied by dissolving the lavender fragrance (oil soluble) in 50% propylene glycol to make it soluble in water and finally by spraying on to the finished fabric by means of spray gun using a pressure of 4kg/cm 2 with the distance of 40cm followed by air drying. To evaluate fastness of finish to perspiration, the fabric was treated with artificial standard perspiration which was prepared according to AATCC test method One gram of sample was sandwiched between two filter papers and 1 ml of perspiration was dispersed and allowed to absorb through filter paper in sample. Treated samples were then tested for antimicrobial property, concentration of fragrance and intensity of fragrance. 2.2 Physical Properties Tensile strength was tested on Scott tester, stiffness on Paramount stiffness tester, wrinkle recovery on Monsato wrinkle recovery tester and air permeability on airflow tester (Model 9025), according to ASTM STD D Performance Properties Antimicrobial Property Antimicrobial property was evaluated by the shake flask method for quantitative evaluation which was developed by modifying Dow Corning test method and AATCC test method This provided the exact number of viable bacteria and thus the extent of bacterial reduction. Bacterial strain used for evaluation was Gram-positive organism Staphylococcus aureus (American type culture collection no.6538). The method was divided into the following four steps: (i) Preparation of Flasks Flasks prepared for evaluation of sample contained 1g of untreated specimen plus the culture medium and in another 1g of treated specimen plus the culture medium. The bacterial culture medium was prepared using 2% of LuriaBroth (LB). 50ml of culture medium was added in each 250 ml Erlenmeyer flask that was then plugged with cotton. (ii) Sterilization Flask of culture medium, petri plates and pipettes were wrapped accurately with paper, tied with thread so that no water can penetrate inside and then sterilized in autoclave at 15 lb/inch 2 pressure and 120 C for 15 min. Petri plates were then kept in oven for drying. (iii) Inoculation Inoculation was done in totally sterile conditions in Laminar flow. The flask at room temperature was inoculated with 0.1% inoculums, prepared by inoculation of 1ml of culture in sterile shaker (180rpm) for 24 h by means of sterile pipette. Then by means of sterilized forceps, sterile test specimens were added to each inoculated flask and labeled. Prepared flasks were then allowed to shake over a rotary shaker at 25 C for 4½ h. (iv) Incubation Inoculum was diluted in sterile test tubes of saline (0.85% NaCl) till 7 folds. Petri plates were poured with 20 ml of sterile culture medium (2% lb % agar-agar) in laminar flow, allowed to solidify for 15 min and labeled. The prepared plates were firstly inoculated with 0.1 ml culture medium of each dilution and poured with sterilized soft agar (0.8% agar-agar solution). Prepared plates were allowed to solidify followed by incubation in an incubator at 37 C for 24 h. The colony forming units (cfu/ml), i.e. number of viable bacterial, were counted and per cent reduction in cell number was calculated using the following formula: %Reduction in Initial cell no. Final cell no. bacterial cell = 100 Initial cell no. This provided exact number of viable bacteria and thus bacterial reduction. The finished samples were subjected to 3 wash cycles in the launder-o-meter and then tested for antibacterial and fragrance release properties Intensity of Fragrance Qualitative Evaluation

3 KAROLIA & MENDAPARA: IMPARTING ANTIMICROBIAL & FRAGRANCE FINISH ON COTTON 101 To have relative idea about intensity of scent sensorial, the evaluation of fragrance was done by panel of 10 judges. Standard sample of each scale was first given to all judges to rank the test specimen. Evaluation was done for all washed, unwashed and perspiration treated specimens which were packed in an airtight polythene bag so that there was no release of fragrance in between evaluation due to air or light. Judges were allowed to take 3-4 whiffs for each sample in an open corridor and rank them in a prepared rating scales. They were also given smell of strong coffee in between to neutralize smell of previous sample. Coding of preference was done and analyzed to obtain relative results of scent intensity Quantitative Evaluation Concentration of fragrance was measured using UV/Visual spectrophotometer. Fragrance was first extracted from 1 g of sample with ethanol for 3 min at 40 C and ensured complete evaporation of ethanol. Extracted fragrance solution was diluted to 1:10 ratio with distilled water. Absorbance of diluted solution was measured on UV/Visual spectrophotometer at λ max 206 by calibrating it with ethanol, which was then converted into concentration according to Beer Lambert s law. This was done for all unwashed and perspiration treated samples after 3 days of application. To test the release rate of the fragrance, 1g finished sample was taken to extract fragrance with ethanol and concentration was calculated. Evaluation was done on next day after application to ensure evaporation of fragrance. Same process was repeated thrice with interval of 4 days. Release rate was measured using the following formula: Release rate Immediate conc.- Conc. after 4 day of fragrance = 100 Immediate conc. 3 Results and Discussion 3.1 Effect of Finish on Physical Properties of the Fabric Tensile Strength As it was expected, the tensile strength decreases by the application of finish. Compared to the control sample the tensile strength was lower for the finished fabric, especially in warp direction and with exhaustion method of application due to higher addon. The reduction may be attributed to crosslinking reaction and use of polycarboxylic acids. None of the treatments cause any drastic reduction in tensile strength, as the reduction is not found to be more than 10% in any of the samples (Table 2) Air Permeability As expected, due to higher add-on (9.6% as compared to 8.2% for padding), the air permeability is less for the fabric finished by the exhaustion method than for the fabric finished by the padding method. The reason of which could be closing of open interstices due to mechanical deposition of the finish (Table 2) Stiffness Bending length of the fabric increases in both the directions with both the application techniques. The reason for this could be mechanical deposition of finishing agents in the open interstices of the fabric or due to crosslinking reaction which made the structure more rigid. Stiffness is found to be slightly higher in the weft direction than in the warp direction (Table 2) Wrinkle Recovery Wrinkle recovery of the fabric increases with both the application techniques, but padding method shows higher wrinkle recovery with lower add-on as well as stiffness than exhaustion method. This could be attributed to microwave curing (Table 2). It has been stated earlier 5 that the microwave curing shows better results as compared to oven curing, because it generates higher frequencies and volumetric heating which minimizes the damages from over drying. 3.2 Effect of Finish on Certain Performance Properties of Fabrics Fabric code Bending length, cm Table 2 Comparison between physical properties of control and finished fabrics Wrinkle recovery angle deg Breaking strength, lb Breaking length, inch (Elongation-at -break) Air flow ft 3 /min/ ft 2 of fabric Warp Weft Warp Weft Warp Weft Warp Weft Control PSC ESC PSC Application of finish by padding method. ESC Application of finish by exhaustion method.

4 102 INDIAN J. FIBRE TEXT. RES., MARCH 2007 Evaluation of finished fabric for certain performance properties has been done to assess its utility and durability Antimicrobial Property S. aureus was used for antimicrobial testing as it is the main cause of body odour and skin disease. The quantitative shake flask test was used to evaluate bactericidal effect. Results reveal that the finish applied by padding shows 98.27% bacterial reduction, whereas that with exhaustion method shows a slightly lower bactericidal effect (Table 3). Citric acid dissociates in water (Scheme 1) and crosslinks with chitosan (Scheme 2), forming chitosan citrate with carboxylic acid residue, which is not esterified with chitosan (a). The carboxylic groups remaining on the chitosan citrate act as fixation sites at high temperature for chitosan on the cellulose fabric (b). 6 When applied on cotton as a polymeric amine, it is positively charged when wet. As the cell wall of the bacteria is negatively charged they would adhere to the chitosan. Due to the opposite electric charges bacterial cell walls could burst which would result in containment of the bacteria Fragrance Depositing Properties and Release Rate Antimicrobial finish was applied by two methods: padding and exhaustion. A fragrance treatment was given to these two finished fabrics. Qualitative and quantitative tests were conducted to assess the performance of fragrance finish. Qualitative evaluation It is observed that the fragrance emitted is better in the case of finish applied by padding than that by exhaustion. The laundry and perspiration treatments and a combination of both the treatments cause great reduction in the fragrance release. The evaluation indicates that the fragrance emitted before laundry as moderate to strong changes to very faint to moderate after laundering. Quantitative evaluation A quantitative evaluation of the samples reveals that there is higher fragrance deposition in case of the finish applied by padding than that by exhaustion method. It is also observed that the finish applied by padding has a lower fragrance release rate, which could be attributed to the deep penetration of host molecules through pressure providing more protection to the guest fragrance molecules. Fragrance release rate is higher after 4 days and it decreases to a certain degree after 8 days because of the release of fragrance Table 3 Comparison between antimicrobial properties of finished fabric Fabric code Cells / ml, cfu / ml % Reduction in cfu / ml Control PSC ESC Table 4 Comparison between fragrance depositing property and release rate of fragrance Fabric code Conc. of fragrance on fabric mm/g Immediately 4 days 8 days Release rate of fragrance, % 4 days 8 days PSC ESC Scheme 1 Reaction mechanism of dissociation of citric acid in water Scheme 2 Reaction mechanism of chitosan and cellulose crosslinking by citric acid molecules attached to surface of fibre and fabric during the initial days (Table 4). It is inferred that the fragrance depositing property is dependent on amount of host molecules on the fabric. The greater amount of hosts could offer more nests for guest fragrance molecules and these complexes are able to decrease the release rate of fragrance. Also the release rate of fragrance is dependent on the environment of host molecules and its complex formation with fibre polymer. Effective complexes can decrease the release rate of fragrance Durability of Antimicrobial and Fragrance Finish to Washing and Perspiration Antimicrobial and fragrance finished fabric was evaluated for the durability of the finish to washing and intermittent perspiration treatment. It is found that the antibacterial activity of the finish applied by exhaust method is lower than that of the finish applied

5 KAROLIA & MENDAPARA: IMPARTING ANTIMICROBIAL & FRAGRANCE FINISH ON COTTON 103 Table 5 Wash fastness of antimicrobial finish Fabric code Cfu / ml after 4½ h % Reduction in Before antimicrobial property washing washing a Control PSC PSC(ac) PSC(al) ESC ESC(ac) ESC(al) a Three wash cycles, ac Acidic perspiration treatment and al Alkaline perspiration treatment. Table 6 Wash fastness of fragrance finish Conc. of fragrance on fabric mm/g Table 7 Perspiration fastness of antimicrobial finish Fabric code Cfu / ml after 4½ h % Reduction in antimicrobial property Without perspiration Acidic perspiration Alkaline perspiration Acidic perspiration Alkaline perspiration PSC ESC Table 8 Perspiration fastness of fragrance finish Fabric code Conc. of fragrance on fabric, mm/g Reduction in fragrance depositing properties, mm/g Without perspiration Acidic perspiration Alkaline perspiration Acidic perspiration Alkaline perspiration PSC ESC Fabric code Before washing washing Reduction in fragrance depositing properties of the finish, mm/g Control PSC PSC(ac) PSC(al) ESC ESC(ac) ESC(al) by padding method. This could be attributed to mechanical deposition of the finish on the fabric. It is observed that the intermittent perspiration treatment reduces the bactericidal activity (Table 5). The fragrance-treated fabric was also evaluated for durability of the finish to laundering. The fabric was also given a perspiration treatment between two laundry cycles. This treatment would simulate a daily wear condition and would give an idea about the fabrics performance in the wash-use-wash conditions. Results also indicate that the concentration of fragrance on fabric decreases with the wash treatments and the reduction is higher in finish applied by exhaustion method then that by the padding method. This could be due to the reduction in concentration of host molecules with washing as well as triggering of fragrance molecules by moisture of water (Table 6) Durability of Antimicrobial and Fragrance Finish to Perspiration Finish was analyzed for its performance against acidic as well as alkaline perspiration. It is observed that the perspiration treatment causes significant reduction in antimicrobial property. Finish applied by padding shows better antimicrobial activity than that applied by exhaustion method. Reaction between alkaline perspiration and esterified carboxylic residue of the finish causes neutralization reaction. Bacterial growth is optimum at neutral ph. Hence, the microbial activity remains lower in case of finish and acidic perspiration combination as compared to that in case of finish and alkaline perspiration combination (Table 7). Results reveal that the finish applied by padding as well as exhaustion shows almost similar trend in fragrance release property. Reduction in presence of alkaline perspiration is similar with both application techniques, whereas for acidic perspiration it is lower with padding than that with exhaustion (Table 8). 4 Conclusions 4.1 The chitosan and citric acid impart good antimicrobial and wrinkle recovery properties to the cotton fabric and its combination with silicon softener facilitates fragrance deposition and helps application of both the finishes together. Hence, it provides higher functionality to the fabric. 4.2 Chitosan and silicon softener applied by padding show better performance, as shown below, against laundry and perspiration as compared to that by exhaustion: Finish shows 79% antibacterial property even

6 104 INDIAN J. FIBRE TEXT. RES., MARCH 2007 after 3 wash cycles. Finished fabric possesses better antimicrobial activity against acidic perspiration as compared to that against alkaline perspiration. Finish applied by padding shows higher fragrance depositing property and release rate against both acidic and alkaline perspiration as compared to that by exhaustion. Acknowledgement The authors are thankful to Dr Anuradha S. Nerurkar, Department of Microbiology and Prof G Nareshkumar, Head, Department of Biochemistry, The M S University of Baroda, for providing support and laboratory facilities received during the work for conducting the tests. References 1 Babu K M, Asian Text J, 12(4)(2003) Knittel D & Scholl Meyer E, Melliand Textilber (Eng), 83(1-2)(2002) Aly A S, Ali H & Samaha S H, Indian J Fibre Text Res, 29(2004) Saad H Y, US Pat 4, 027, 068; Chem Abtr, 87(1977) 69959h. 5 Vukusic S B, Katovic D & Schramm C, Text Res J, 73(8)(2003) Zhang Z, Jinmin Ji, Yanliv H & Donghvi C, Text Res J, 73(12)(2003) 1103.