1.Materials
PA-6 staple fibers which were supplied by MakaremTex Co., ABO Rawash, Giza, Egypt. These fibers were obtained from recycling bottles.
Dimethyl alkylbenzyl ammonium chloride belongs to Aromatic antimicrobial substrate (Ar-AS) was supplied by Sigma – Aldrich.
Polydiallyl dimethyl ammonium chloride belongs to Aliphatic antimicrobial substrate (Al-AS) was supplied by Sigma – Aldrich.
2. Methods
2.1. Semi Industrial Scale Production of PA-6 Fibers Containing AS
Adaptation and development of pilot scale conditions which have been set up, previously [10].
PA-6 fibers (1.0 Kilogram) (Figure 1A) were treated in a Stainless steel conical tank (Figure 1B) containing antimicrobial substrate (aromatic or aliphatic) at required concentration of AS, temperature and duration (Figure 1C). At the end of treatment process the samples were filtered and directly squeezed using centrifuging machine(Figure 3D). Washing: Antimicrobial polyamide fibers were washed with hot water for 15 min., with cold water for 10 min. Drying: Antimicrobial squeezed PA-6 fibers were dried at 100°C until constant weight was received. Finally the antimicrobial assessment of treated PA fibers with AS samples was investigated.
Figure (1)
2.2. Industrial scale production of PA fibers containing AS
Technological parameters for the production of Antimicrobial PA fibers on industrial scale as following (Figure 2):
a- Scouring of PA fibers were treated for 30 min. at 100°C in a bath containing: Sodium hydroxide, 2-4 %; Non ionic detergent, 4 g/L; Washing: At the end of souring the R-PET fibers were washed: With hot water for 15 min., with cold water for 10 min.
b- Treatment with AS: The washed PA-6 fibers were imparted antimicrobial properties by treatment with aqueous solutions of aromatic antimicrobial substance (Ar-AS) under the following condition: AS, 8% (owf); pH,11; Treatment Temperature, 90°C; Treatment Time, 60 min. and M:L, 1: 10. Squeezing: PA-6 fibers treated with AS were squeezed using centrifuging machine. Washing: Antimicrobial PA fibers were washed with hot water for 15 min., with cold water for 10 min. Drying: Antimicrobial squeezed PA fibers were dried at 100°C until constant weight was received.
Figure (2)
Analysis
1. Antimicrobial Assessment
Antimicrobial activity of PA-6 fibers finished with different AS (aromatic or aliphatic) was quantified using the Shake Flask Method. In this case the antimicrobial activity of immobilized antimicrobial substances is determined under dynamic contact conditions according to ASTM standard test method 2149 (2001).
Materials: Nutrient broth medium (NB), one set of samples&100.0 ml sterile conical flasks
Nutrient broth medium Composition:
Ingredients:
|
g/l
|
Yeast extract
|
2.0
|
Peptone
|
5.0
|
Meat extract
|
1.0
|
NaCl
|
5.0
|
pH 7.4 ± 0.2
|
Qualitative evaluations were carried out in nutrient broth according to16-21. The inoculation of pathogenic microorganisms used in this study were Gram positive bacteria Staphylococcus aureus (ATCC6538) and Gram negative bacteria [)Escherichia coli (ATCC25922)]was prepared from fresh overnight broth cultures using nutrient broth medium that were incubated at 37°C. The inoculum suspension of pathogenic strains was prepared and adjusted to approximately 0.5 McFarland standard (1.5×108/ml) [11], 15.0 µl of the Bacterial suspensions was inoculated separately into each 100.0 ml conical flask containing 25.0 ml of the sterile nutrient broth medium (NB). The samples were applied on these tested strains by using shake flask method to calculate the antimicrobial activity is expressed throughout (%) reduction of bacterial count by calculated colony forming unit (CFU) of these tested strains after treated with that tested samples compared to the number of the microorganisms cells surviving in the control flask after 24 hours incubation period and at 37°C for bacteria and pathogenic22-25.
All results were expressed according the following equation:
% CFU [Relative Reduction] = (A- B/A)×100
Where:-
A: the number of microorganisms present on control flask contains pathogenic strains only without any treatment.
B: the number of microorganisms present tested flasks after applying testedtreatedsample.
2. Carboxylic content was measured according to the method described by Shalaby et al 2018 [11].
3. Surface structure and the morphology of all fibers samples were characterized by a JEOL-Model JSM T20 scanning electron microscope (SEM), operating at 19 kV to obtain photomicrographs of fabrics surfaces.
4. XRD spectra were obtained from the analytical EMPYREM2 (Netherland) with Cu radiation (λ=1.5406 Å), the tube operated at 45 KV, and 30 mA, 2θ =10-60, step size = 0.026, step time 20 sec/step.
5. Thermal analysis
(a) The differential scanning calorimetry (DSC) for parent and treated nonwoven fabrics was carried out using DSC Perkin-elmer-7, USA thermal analyzer. The rate of heating was adjusted at 10°C/min. Thermograms were recorded from 25°C to 400°C under nitrogen atmosphere.
(b) The thermogravimetric analysis (TGA) for parent and treated nonwoven fabrics was carried out using TGA-50 Shimadzu thermal analyzer. The rate of heating was adjusted at 10°C/min. Thermograms were recorded from 25°C to 600°C under nitrogen atmosphere.
6. Physico-mechanical properties of antimicrobial polyamide nonwoven fabrics were determined in Textile Research and Technology Institute -NRC textile fibers and fabrics lab.
7. Production of needle punched antimicrobial PA nonwoven fabrics
The produced on industerial scale antimicrobial PA fibers have been used for the manufacturing of corresponding nonwoven fabrics. This was carried out using mechanical needle punched process on the production Line of EgypTex Co., in 6 of October City, Giza Egypt.
8. Production of air-laid antimicrobial PA-6 nonwoven fabrics
The produced on industerial scale antimicrobial polyamide fibers have been used for the manufacturing of corresponding nonwoven fabrics. This was carried out using air-laidpunched process on the production Line of Yanssen Co., Abo-Rawash, Al-Abour City, Egypt.