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Preparation and Properties Evaluation of Tencel/ PET Low Melting Point
Fiber Dressing Fabric coated by UV Cross-linked Chitosan
Jia-Horng Lin
1, 2,a, Chao-Tsang Lu
3, b*, Wen-Cheng Chen
4, Jin-Jia Hu
5and Ching-Wen Lou
6, a*1Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite
Materials, Feng Chia University, Taichung City 407, Taiwan, R.O.C.
2School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan, R.O.C. 3Institute of Life Sciences, Central Taiwan University of Science and Technology, Taichung 406,
Taiwan, R.O.C.
4Advanced Medical Devices and Composite Laboratory, Department of Fiber and Composite
Materials, Feng Chia University, Taichung City 407, Taiwan, R.O.C.
5Department of Biomedical Engineering National Cheng Kung University, Taiwan, R.O.C. 6Institute of Biomedical Engineering and Material Science, Central Taiwan University of
Science and Technology, Taichung 406, Taiwan, R.O.C. *corresponding email: [email protected], [email protected]
Keywords: Chitosan, Composite membrane, wound dressing, PET(Polyethylene terephthalate)
Abstract. In this study, Tencel staple fibers and PET low melting point fibers (LMPET) were blended to prepare composite nonwovens, with change of blending ratio of Tencel/LMPET, hot-baking time and temperature. By measurement of mechanical properties, the optimal parameters were found to become dressing covering material after analysis of experimental data, with adjustment of strength, breathability and flexibility of nonwovens. During membrane preparation, 3 % chitosan solution was exposed to UV ray for 1, 3, 5 minutes, and then manufactured into membrane by Freeze Dryer, in order to explore broken bond whether happened on chitosan structure and to further manage chitosan membrane degradation rate. With analysis of UV irradiation time influencing on membrane releasing, membrane at the same size was immersed in PBS for degradation test. According to mechanical and degradation results, it is showed that, 100 % Tencel nonwovens had better breathability and strength than that mixed with 30 % LMPET, and membrane had the most stable degradation rate after 5 min irradiation of chitosan solution. Finally, using most stable chitosan and Tencel nonwovens, Tencel/ Chitosan composite dressing fabric was compounded by coating.
Introduction
Lyocell is a cellulose fiber made from solvent spinning of wood pulp dissolved in NMMO. NMMO solvent for producing Lyocell fibers needs not by chemical reaction, not accompanying with cellulose decomposition when cellulose fiber is dissolved in NMMO. This technology makes use of characteristic that emerging hydrogen bond made from NMMO and polyhydroxy on cellulose brings about cellulose dissolution, takes closed flow process, dissolves cellulose into spinning solution and then produces cellulose fiber after Dry-jet wet spinning. In the process, NMMO can be recycled and use again whose recovery rate is as high as 99% or more, causing no environmental pollution as well as decomposition of waste products in natural environment after abandoning. Therefore, NMMO has double characteristics of cleaner production and decomposition for environmental protection [1].
Chitin, β-1,4 bonded straight-chain carbohydrate polymer, is composited of N-acetyl-Dglucosamine and glucosamine. It is common in natural organism, and rich in epidermis
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organization ranging from tardigvada, wreath to mollusc invertebrate. It is estimated that, chitin contains inferior to cellulose in nature, that is, it is the second natural polymer of global reserves. Each year, one hundred thousand metric tons chitin is produced all over the world [2-3]. Chitosan, with quite abundant reserves in the natural world, can be got by deacetylation with low cost, better biocompatibility and biodegradation, so it is widely used in biomedical, food and agricultural fields currently [4].
Experimental
Materials and Methods
1.7 D Tencel® fiber, with length of 51 mm and tenacity of 38.0- 42.4 g/De, was provided by TENCEL. 51mm length 4.1 D low melting point PET fiber(LMPET), with 110°C melting point, 3.7 g/De tenacity and 4.5 % thermal contraction, was bought from Republic of Korea. chitosan of 85 % dealcholization degree was purchased from Global biological technology Co., LTD. The maximum tensile strength, the maximum tearing strength and permeability were measured by CNS 5610 - 4.3.2, CNS 5610 - 4.10.1 and ASTM D737 standards, respectively.
Chitosan Membrane Preparation and Light Degradation Test
1 ml acetic acid was poured into 99 ml deionized to form 1 % acetic acid solution(as solvent), following by 3 g chitosan powder addition until complete dissolution after stirring. Next, chitosan solution was dipped slowly in culture dish via micropipette, and then exposed to 850 mW/cm3 UV ray for different irradiation time (0 min,1 min,3 min,5 min), then laid in the freezer (about -50 °C) for 24 hrs, and then neutralized with 1 ml NaOH solution. Finally, translucence dried chitosan membrane was prepared after 3 hrs soaking, following by washing in deionized water, freezing for 24 hrs in freezer, drying for 24 hr in Freeze dryer, as well as irradiating by UV ray for different time. Afterwards, the membrane was cut with the same size, then weighed (Wt), and then immersed in PBS (Phosphate-Buffered Saline), and put in 37 °C bath for degradation test. After 5, 7, 9, 14 days, the samples were weighed (Wo) via cleaning and drying. The degradable weight loss is calculated as:
Results and Discussions
Fig.1 shows influence of heat treatment temperature to air permeability of Tencel composite nonwoven fabric. It is found that, with increase of temperature, air permeability of fabric is improved owing to enhancement of LMPET melting degree. But fabric’s permeability tends to be downward when warming up to above 170 °C, because partial melting of LMPET at higher temperature leads to uneven thermal bonding effect of LMPET to Tencel composite nonwoven fabric.
Fig.2 reveals effect of hot-baking temperature to maximum tensile strength and maximum tearing strength of 100 % Tencel fabric. It is concluded that, cohesive force among fibers is increased due to extrusion by heat treatment mold, resulting in approaching tend of tensile stress in MD and CD directions. In additional, by comparison of Fig. 2 results, we find that , LMPET addition achieves no anticipated reinforcing effect to maximum tensile strength of Tencel fabric. Even though LMPET has limited reinforcing effect to mechanical properties of fabric at X-Y direction, it has obvious benefit for peeling resistance of stereo-structure Tencel fabric at Z
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direction.Fig.3 shows hot-baking temperature influencing on breathability of 100 % Tencel fabric. We conclude that, with increase of heat treatment temperature, breathability of 100 % Tencel fabric is decreased, because extrusion by heat treatment mold and sizing of Tencel staple fibers at higher temperature make fibers density enhanced. Fig.4 indicates softness of 100 wt% Tencel and 70 wt% Tencel / 30 wt % LMPET fabrics after different hot-baking temperature. As shown in figure, it is revealed that, their softness would be lower by increasing treatment temperature; additionally, the control group without LMPET, has the highest softness. That is because the LMPET melting degree is higher by heating up treatment temperature. Fig.5 presents comparative results of air permeability and softness of Chitosan/Tencel composite dressing fabric and Tencel composite nonwoven fabric. We find that, composite dressing fabric after coating has lower air permeability and softness. That is because coating hinders fabric ventilation, causing more bonding points among fibers and compact structure after coating.
Fig.6 shows weight loss of membrane produced by different UV irradiation of chitosan solution after soaking in PBS. It is observed that, after irradiation for 0 or 5 min, chitosan weight loss starts to be gentle on 9th day; furthermore, 5min irradiation weight loss is more than 0 min irradiation. After 1min irradiation, chitosan membrane tends to degrade persistently, inferring that chitosan C1-O-C4 produces breaking bond without generating deacetylation after 1 min UV ray irradiation. Moreover, after 3min irradiation, weight loss generates by a large margin from 5th to7th day, and begins to go up from 7th to14th day. The reason for responding weight loss is that Chitosan solution produces a large amount of free amino after 3 min irradiation by UV ray, making chitosan soaked in PBS solution happen absorption even though chitosan weight loses in PBS.
Fig.1 Effect of heat treatment for 15 min to air permeability of Tencel composite nonwoven fabric containing 30 wt % LMPET
Fig.2 Maximum tensile strength and maximum tearing strength of 100 wt% Tencel fabric after different hot-baking temperature (140, 150, 160, 170, 180 °C) for 15 min
Fig.3 Air permeability of 100 %Tencel fabric after different hot-baking (140, 150, 160, 170, 180 °C)for 15 min
Fig.4 Influence of heat treatment temperature on softness of Tencel composite nonwoven fabric containing 30 wt% LMPET and 0 % LMPET (the
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control group)
Fig.5 Comparison of breathability and softness for Chitosan /Tencel composite dressing fabric and Tencel composite nonwoven fabric
Fig.6 Weight loss of membrane produced by different UV irradiation of chitosan solution after soaking in PBS
Conclusion
For 70 wt%/30 wt% LMPET after hot-baking molding, LMPET reinforcing effect to Tencel staple fiber is limited. And the maximum tensile strength of 100 % Tencel composite nonwoven fabric is nearly to that of LMPET reinforced Tencel composite nonwoven fabric. Afterwards, 100 % Tencel composite nonwoven fabric was coated with Chitosan to produce functional dressing fabric of special structure.
From degradation test, it is found that, changing UV irradiation time is effective to control degradation speed of chitosan in PBS solution. After irradiation for 5 min, chitosan membrane tends to have the most stable structure of all other irradiation times. Therefore, 5 min UV ray irradiation is the optimum manufacturing condition for Chitosan membrane.
Using coating chitosan on fabric by printing makes fabric’s strength more stable, and increases fabric’s stiffness, but decreased its breathability largely because coating process blocks air ventilation.
Acknowledgements
The authors would like to thank the National Science Council of the Republic of China for financially supporting this research under Contract NSC-99-2622-E-166-004-CC3.
Reference
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