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1.
Chitosan is a natural non-toxic biopolymer and is widely used in various fields because of the antimicrobial activities. In this study, the properties of nylon textiles grafted with chitosan oligomer or chitosan polymer after being activated by open air plasma were evaluated. Results showed that nylon textiles grafted with chitosan polymer had better antibacterial performances than those grafted with chitosan oligomer. Air plasma activation at a higher speed (26 m/min) for a few times facilitated the grafting of chitosan and critically determined the antibacterial activities. Further treatment with air plasma after grafting improved the antibacterial effect. Overall, chitosan-grafted nylon textiles showed good antibacterial potential as well as biocompatibility.  相似文献   

2.
Semi-interpenetrating polymeric network (semi-IPN) hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-sodium methacrylate) [P(HEMA-co-SMA)], and chitosan with different molecular weights were prepared by crosslinking with ethylene glycol dimethacrylate (EGDMA) and poly(ethylene glycol) diacrylate (PEGDA) and their gelation time, water content, mechanical properties, and morphology were investigated. In consideration of the influence of the molecular weight of chitosan, there is no big difference in the water content, while tensile properties and compressive modulus increased as the molecular weight of chitosan increased. The water content increased and tensile properties and compressive modulus decreased with increasing SMA concentration. Considering the effect of the crosslinking agent, PEGDA had higher water content and lower tensile and compressive moduli than EGDMA. It is suggested that PHEMA/chitosan and P(HEMA-co-SMA)/chitosan semi-IPN hydrogels with different structures and physical properties can be prepared depending on the molecular weight of chitosan, the copolymerization with SMA, and the crosslinking agent type.  相似文献   

3.
Graft copolymerization of acrylamide onto commercial acrylic fibers was carried out using benzoyl peroxide as a free-radical initiator in aqueous medium within the 75–95 °C temperature range. In this study, the effects of initiator and monomer concentration, the amount of fiber, polymerization time, and temperature on the graft yield were investigated. The optimum concentration for initiator was found to be 2.0×10−3 mol/l and the optimum temperature of 85 °C. The activation energy of the reaction was calculated to as 35.81 kJ/mol at the temperature interval of 75–95 °C. The structures and morphologies characterization of grafted fibers was investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The thermogravimetric analysis data showed that the thermal stability of the acrylic fibers increased with graft yield. The scanning electron photographs showed that the homogeneous appearance of the fiber surface changed and a shell-like heterogeneous structure occurred at the surface with an increasing degree of grafting. The moisture content, water absorption, dyeability, and antimicrobial activity of grafted acrylic fibers were also reported. The results showed that grafting of polyAAm improved the moisture contain, water absorption, dyeability, and antimicrobial activity of fiber.  相似文献   

4.
In this study, we attempted to evaluate a novel use of sericin-fixed silk fiber (SFx) as an immobilization support of enzyme. Sericin was fixed on the silk fiber using glutaraldehyde as a fixation reagent. After 6 hours of fixation, the degree of fixation increases linearly with linear decrease of the amount of bound α-chymotrypsin (CT). This suggests that the increase of the degree of fixation is due to the further crosslinking of free aldehyde groups on the surface of sericin-fixed silk fiber (SFx). Even though perfect fixation was not achieved, sericin did not dissolve seriously and could be removed by further washing. The specific activity did not differ significantly after 6 hours of fixation. The activity of immobilized CT on SFx decreased to its half after 6 hours of incubation at 50°C. However, it retained 78% of initial activity even after 1 hour of treatment with 100% ethanol. As a result, the SFx could be used as an immobilization support of enzyme in non-aqueous media at ambient temperature.  相似文献   

5.
Silk fibrillation, one major weakness of silk fibers, can lead to undesirable fabric appearance. In this research, an effective method for reducing the fibrillation of silk fibers through the graft copolymerization with methyl methacrylate (MMA) has been developed. The major copolymerization factors such as the initiator concentration, MMA monomer concentration, reaction time and temperature were investigated. An AATCC Crockmeter was used to rub the fabric to simulate the abrasion in production to generate the fibrillation. The microscope observation and the evaluation of fibrillation index (FI) were applied to assess the degree of fibrillation of silk fibers. The optimum graft copolymerization factors were obtained. Instrumental analyses, such as FTIR, TG and SEM, proved that the silk fabric had been successfully grafted with MMA monomers. The fibrillation of the grafted silk fibers was considerably reduced since the coated PMMA can protect the silk fiber. In addition, the physical properties such as the crease recovery, breaking strength, and the breaking length of the grafted silk fabrics were also improved.  相似文献   

6.
To synthesize a series of novel temperature sensitive hydrogels, N-tert-butylacrylamide (NtBA) and acrylamide (AAm) were used as the comonomers and polymerized by free-radical crosslinking copolymerizarion. The poly(ethylene glycol) (PEG) with molecular weight of 400, 4000 and 6000 g·mol-1 was used as the porogen. The equilibrium swelling capacity, swelling/deswelling kinetics and diffusion parameters of obtained hydrogels were systematically evaluated. As revealed by SEM micrographs, the macroporous structure of hydrogels can be modulated by the crosslinking level, PEG molecular weight and dosage. FTIR analysis demonstrated that the porogen PEG was completely leached out of the gel matrix. Compared with the conventional hydrogels, the PEG-modified (PGel) hydrogels exhibited enhanced temperature sensitivity and superior kinetics during the swelling, deswelling and pulsatile swelling processes. Controlled release of salicylic acid also demonstrated the good usability of PGel hydrogel, which rendered it great potential for controlled drug delivery systems.  相似文献   

7.
A new fiber-reactive chitosan derivative was synthesized in two steps from a chitosan of low molecular weight. First, a water-soluble chitosan derivative, N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (short for HTCC), was prepared by reacting chitosan with 2,3-epoxypropyltrimethylammonium chloride. Second, HTCC was further modified by reacting with N-(hydroxymethyl)-acrylamide to prepare a fiber-reactive chitosan derivative, O-methyl acrylamide quaternary ammonium salt of chitosan (short for NMA-HTCC), which can form covalent bonds with silk fiber under alkaline conditions. The chemical structure of NMA-HTCC was characterized by Fourier transform infrared spectrum (FTIR) and nuclear magnetic resonance (NMR). The substitution degree of HTCC and the double-bond content of NMA-HTCC were tested. Then NMA-HTCC was used for antibacterial finishing of Bombyx Mori silk fabric. The results showed that silk fabric treated with NMA-HTCC had a significantly improved antibacterial activity to Staphylococcus aureus and Escherichia coli, and the antibacterial activity of silk fabric finished by NMA-HTCC was much better than that finished by chitosan and HTCC. Bombyx Mori silk fabric modified with NMA-HTCC demonstrated excellent durable antibacterial activity, even after 50 repeated launderings, the bacterial reduction rate of silk fabric maintained over 95 %.  相似文献   

8.
Carboxyl group-terminated poly(N-isopropylacrylamide) (PNIA-COOH) was synthesized via radical polymerization of N-isopropylacrylamide (NIA) using mercaptoacetic acid (MAA) as a chain transfer agent. The molecular weight of the PNIA-COOH was controlled by changing the molar ratio of MAA to NIA. A water-soluble chitosan derivative, N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), was also synthesized by reacting chitosan with glycidyltrimethylammonium chloride. Then, chitosan-g-PNIA and HTCC-g-PNIA copolymers were synthesized using the “graft-onto” method by reacting PNIA-COOH with chitosan and HTCC, respectively. The formation of the grafted copolymers was confirmed by Fourier transform infrared spectroscopy, solubility test in water, and scanning electron microscopy — energy dispersive spectroscopy. The thermo-responsive behaviors of the grafted copolymers and the change in lower critical solution temperature (LCST) were also studied. Chitosan-g-PNIA was insoluble in water and behaved like a thermo-responsive hydrogel due to the crosslinking-point action of the chitosan backbone. The swelling ratio of chitosan-g-PNIA increased with increasing PNIA content. HTCC-g-PNIA behaved as a water-soluble thermo-responsive polymer. Compared to the homo PNIA, the LCST of HTCC-g-PNIA was slightly increased.  相似文献   

9.
The flame resistant finishing of silk fabric is still a challenge because most of the available treatment methods usually result in insufficient laundering durability. In this paper, a vinyl phosphorus-based monomer diethyl-2-(methacryloyloxyethyl) phosphate (DEMEP) was applied onto silk fabrics by graft copolymerization technique using potassium persulfate as an initiator. FT-IR spectra and amino analysis showed the evidence of the reaction between DEMEP and silk. The silk fabrics treated with DEMEP have excellent self-extinguishing property when the DEMEP add-on is over 50 % wt of silk fabrics. The LOI of treated samples is at least 28 % when the weight gain is 10 %. After being subjected to 30 hand wash cycles, DEMEP treated silk fabric can still pass the vertical flammability test. Thermal gravimetric (TGA) and differential thermal analysis (DTA) were applied to explore the thermal decomposition of silk fabrics treated with DEMEP. The initial decomposition temperature of silk fabric treated with DEMEP was shifted to a lower temperature. And at the end of decomposition at 700 °C, the char residue of silk fabric treated with DEMEP was higher than that of the control sample.  相似文献   

10.
Aramid fibers have been known to difficult to dye with conventional dyes and dyeing techniques because of its extremely high crystallinity and compactness. In order to make the aramid fibers dyeable to a bright color in deep shade, meta-aramid fabrics were photografted under continuous UV irradiation with dimethylaminopropyl methacrylamide (DMAPMA) and benzophenone as a monomer and a hydrogen-abstractable photoinitiator respectively. Several factors affecting the photografting treatment of the meta-aramid fabrics were investigated including monomer and photoinitiator concentrations. ATR, ESCA and SEM analysis indicated significant alterations on the chemical structure and atomic composition of the photografted fabric surface and the fabric surface was covered with the grafted polymers. While the pristine meta-aramid fabrics showed no appreciable dyeability to the α-bromoacrylamide type reactive dyes, the grafted aramid fabrics showed the remarkably enhanced dyeability to the reactive dyes, which was proportional to the graft yield indicating the covalent bond formation between the dyes and the secondary amino groups in the grafted DMAPMA. In case of C.I. Reactive Red 84, a K/S value of 14.8 can be obtained with the grafted meta-aramid fabrics with a graft yield of 7.6 % (w/w). Also and the color fastness properties of the dyed fabrics was excellent in the conditions of washing, rubbing and solar irradiation.  相似文献   

11.
Bombyx mori (B. mori) silk was modified with the nano-TiO2 and chitosan dispersion system by the crosslinking reactions of citric acid (CA) and maleic anhydride (MA). The average size of the nano-TiO2 particles in the aqueous dispersion system was 36.7 nm. The scanning electron microscopy (SEM) micrographs showed that the nano-TiO2 particles were spherical and homogeneously dispersed in the dispersion system, and the surface ofB. mori silk fiber treated with the nano-TiO2 and chitosan dispersion system was rougher than that of the untreated one. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) Spectrometry indicated that the crystallinity of theB. mori silk fiber increased after treatment. It was also found that the nano-TiO2 and chitosan contributed to significantly enhance the mechanical properties including breaking strength, breaking elongation, initial modulus, rupture work, and elastic recovery property of theB. mori silk fiber. The wrinkle-resistant performance of the treatedB. mori silk fabrics was also greatly improved.  相似文献   

12.
In this research, a novel cotton fiber with a silk fibroin (SF) coating was prepared by the oxidation of a cotton thread with sodium periodate and subsequent treatment in a solution of silk fibroin. The structures of both the oxidized cotton samples and the SF modified cotton samples were investigated by Fourier transform infrared (FT-IR) in combination with X-ray photoelectron spectroscopy (XPS) analysis. Other performances such as surface morphology and breaking strength were also studied. The results indicated that the weight of the oxidized cotton samples increased during SF treatment, while that of the un-oxidized cotton (pure cotton) samples reduced after SF treatment. Compared with the pure cotton samples, the oxidized cotton clearly showed a characteristic absorption band at 1730 cm−1 due to the stretching vibration of the C=O double bond of the aldehyde group. After being treated with the SF solution, the oxidized cotton fiber showed a weakened characteristic absorption band at 1730 cm−1 and a new absorption band at round 1540 cm−1, suggesting the formation of C-N bond between aldehyde groups in the oxidized cotton and primary amines in the silk fibroin. The results were also confirmed by XPS analysis. Compared with the oxidized cotton samples, the SF treated cottons had relatively smooth surfaces, similar breaking strength, and the improved wrinkle recovery angles. The results in this research suggest that cotton based materials with protein coating can be achieved without using any other crosslinking agents by the method introduced.  相似文献   

13.
Continuous photografting/crosslinking of polyethyleneglycol dimethacrylate oligomers onto cotton using a water-soluble benzophenone photoinitiator was investigated. Photografting increased with increasing irradiation dose, oligomer concentration and photoinitiator concentration. Maximum grafting efficiency of DM 400 and 600 were 83% and 79%, respectively. The photografting increased the wrinkle resistance of cotton implying surface crosslinking of cotton. Both surface crosslinking and bulk crosslinking of cotton were accomplished via dual curing of a mixed formulation containing both a thermally curable component (BTCA/SHP) and a UV-curable component. The wrinkle resistance of the crosslinked cotton was found to be higher when cured by thermal curing after UV curing rather than by UV curing after thermal curing due to the facile post-polymerization of the UV active component. The presence of crosslinks in the dually crosslinked cotton was verified with FT-IR and thermogravimetric analysis.  相似文献   

14.
Jute yarns were cured with acrylic acid (AA) and phosphoric acid (PA) using UV radiation in order to prepare selective ion adsorbent. A series of formulations were prepared in methanol containing varying percentages of (10–70 %) of AA and 2 % photo-initiator (PI) (Darocur-4043). jute yarns were soaked in this formulation for various soaking times (10–30 min) and cured under UV radiation of different intensities (20–50 UV passes). Concentration of AA, soaking time and intensity of UV radiation were optimized based on polymer loading (PL). The maximum PL (21 %) was observed for 50 % AA solution for 20 min soaking time at 40 UV passes. Various formulations were prepared using 5–15 % (w/w) of phosphoric acid, 50 % AA and 2 % PI in methanol. Then jute yarns were soaked in this solution for 20 min and irradiated at 40th UV pass. The concentration of PA was again optimized for maximum PL. It was found that the formulation containing 10 % PA, 50 % AA, 38 % methanol and 2 % PI showed 70.95 % of PL. To investigate the adsorbent behavior, a 10 ppm CuSO4 solution was prepared and then grafted yarns were soaked in the solutions for 30–300 min at different conditions. After withdrawing the yarns, the remaining copper in the solution were measured by atomic absorption spectrophotometer (AAS). It was revealed that copper was successfully removed by using the grafted jute yarns.  相似文献   

15.
Summary The effect of water stress on yielding capacity of potatoes was studied in 3 years using four different levels of soil water potential (0.7, 1.9, 3.4 and 7.8 atm.) in experiments in specially adapted structures that excluded uncontrolled water supply. Seed tubers from these crops were planted in the following years to investigate effects of water stress on their subsequent performance. Limited soil moisture availability decreased yield and the number and size of tubers. The growing period was shortened by 1–4 weeks and dormancy period by 2–8 weeks. In the following year, seed produced under conditions of moisture stress gave plants with 20% fewer stems. 24–33% less yield, 18–22% fewer tubers and 19–22% fewer large tubers than plants from seed produced under abundant water supply. It is concluded that the yield potential of seed tubers can be improved by careful attention to the availability of soil moisture during their production.  相似文献   

16.
Continuous photografting onto polypropylene fabrics in the absence of inert gases was carried out to improve hydrophilic property of PP fabrics, which was padded with a formulated solution of 2-hydroxyethyl methacrylate(HEMA) and benzophenone as a monomer and a photoinitiator, respectively. The grafting yield increased with increases in benzophenone concentration up to 30 % on the weight of the monomer and UV energy up to of 38 J/cm2, while 30 % HEMA concentration was optimal for the grafting efficiency. The physicochemical properties of the grafted PP fabrics were monitored by FT-IR, SEM, zeta potential, and dyeability to a cationic dye. The grafting increased O1s/C1s content and remarkably produced more negative zeta potentials compared with the pristine PP fabric. Also the grafted PP showed the increased dyeability to cationic dyes with increasing graft yield resulting from the enhanced electrostatic interaction between the dyes and negatively charged surface of the grafted PP fiber. In addition, improved hydrophilic property of grafted PP fabrics was ascertained by more rapid water wetting time and higher water absorbency.  相似文献   

17.
The aim of this study was to first evaluate whether the chitosan hydrochloride-genipin crosslinking reaction is influenced by factors such as time, and polymer/genipin concentration, and second, to develop crosslinked drug loaded microspheres to improve the control over drug release. Once the crosslinking process was characterized as a function of the factors mentioned above, drug loaded hydrochloride chitosan microspheres with different degrees of crosslinking were obtained. Microspheres were characterized in terms of size, morphology, drug content, surface charge and capacity to control in vitro drug release. Clarithromycin, tramadol hydrochloride, and low molecular weight heparin (LMWH) were used as model drugs. The obtained particles were spherical, positively charged, with a diameter of 1–10 μm. X-Ray diffraction showed that there was an interaction of genipin and each drug with chitosan in the microspheres. In relation to the release profiles, a higher degree of crosslinking led to more control of drug release in the case of clarithromycin and tramadol. For these drugs, optimal release profiles were obtained for microspheres crosslinked with 1 mM genipin at 50 ºC for 5 h and with 5 mM genipin at 50 ºC for 5 h, respectively. In LMWH microspheres, the best release profile corresponded to 0.5 mM genipin, 50 ºC, 5 h. In conclusion, genipin showed to be eligible as a chemical-crosslinking agent delaying the outflow of drugs from the microspheres. However, more studies in vitro and in vivo must be carried out to determine adequate crosslinking conditions for different drugs.  相似文献   

18.
The developmental pattern of jicama (Pachyrhizus erosus (L.) Urban) was studied by sampling plants aged 20 to 36 weeks at weekly intervals. There was an increase in all characteristics of foliage: fresh and dry weight, number of leaves per plant, main stem length, number of leaves, nodes and internodes of the main stem; and in all root characteristics: fresh and dry weight, diameter and length. The chemical analysis was determined for roots at different plant ages. The range values for dry matter were 16.19–22.28%, protein 1.11–1.62%, fat 0.553–0.867%, crude fiber 0.3048–0.3943%, and ash 0.669–1.089%. The chemical constituents fluctuated with age but without specific trends. These values are considered the first record of roots produced by plants grown in Mexico.  相似文献   

19.
The objective of this research was to investigate the critical water content (θ c) and water stress coefficient (K s) of soybean plant under deficit irrigation. This research was conducted in a plastic house at the University of Lampung, Sumatra in Indonesia from June to September 2000. The water deficit levels were 0–20%, 20–40%, 40–60%, 60–80%, and 80–100% of available water (AW) deficit, arranged in Randomized Completely Block (RCB) design with four replications. The results showed that the soybean plant started to experience stress from week IV within 40–60% of AW deficit. The fraction of total available water (TAW) that the crop can extract from the root zone without suffering water stress (p) was 0.5 and θc was 0.305 m3 m−3. The values of K s at p=0.5 were 0.78, 0.86, 0.78, and 0.71 from week IV to week VII, respectively. The optimum yield of soybean plant with the highest yield efficiency was reached at 40–60% of AW deficit with an average K s value of 0.78; this level of deficit irrigation could conserve about 10% of the irrigation. The optimum yield of soybean plant was 7.9 g/pot and crop water requirement was 372 mm.  相似文献   

20.
The surface of silk is modified by a cationic reagent, N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride(CHTAC) in order to enable the fibre to be dyed with superfine pigments by an exhaust process. The effects of cationization pretreatment conditions such as the amount of cationic reagent, pH, treatment temperature and time on color yield are discussed in detail. The result shows that the condition suitable for modification treatment is that the concentrationc of cationic reagent is 10 g/l, pH 8, liquor to goods ratio of 100:1 and 60°C for 30 min. The white index decreases with the increase of alkali of cationic treatment. The crock fastness and wash fastness of silk dyed by pigment exhaust dyeing achieve 3–4 and 4 scale, respectively. The treated silk fabrics still retain a soft handle because the bending rigidity B and hysteresis 2HB increase slightly after cationization pretreatment and dyeing procedure. It has been demonstrated that properties of surface modified silk dyed with superfine pigment by exhaust process are acceptable.  相似文献   

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