Surface Morphology and Properties of Bombyx mori Silk Fibroin Fiber Treated with I-2-KI Aqueous Solution

The surface morphology, thermal and mechanical properties of Bombyx mori silk fibroin (SF) fiber treated with a 1.23 N iodine-potassium iodide (I-2-KI) aqueous solution were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry, thermogravimetric analysis, and tensile measurements to clarify the effects of the iodine treatment. SEM and AFM analyses indicated that the SF fiber surface became rougher by the absorption of polyiodide ions. The mechanical properties of iodinated SF showed an increase in Young's modulus, and strain remained constant although ultimate tensile strength slightly decreased. The thermal stability of SF molecules was greatly enhanced by iodine treatment. Iodinated SF fibers should be an attractive candidate for biomedical applications such as for producing antimicrobial filters, iodine containing wound-healing anion exchange fibers, etc.ArticleTEXTILE RESEARCH JOURNAL. 79(14):1305-1311 (2009)journal articl

The Canadian Society for Bioengineering Compressive behavior of hemp fiber (Cannabis sativa L.) stalks

Abstract. Compressive strength of hemp (Cannabis Sativ L.) stems is of great importance for the design of hemp handling and processing machines. A study was carried out to evaluate the compressive behavior of hemp stalks. Two varieties of hemp stalks produced for single purpose (Alyssa) and dual purposes (Petera) in Manitoba, Canada were used in the study. Each variety of hemp stalk was divided into three height regions of the stem: upper, middle and lower. The hemp stem specimens were cut into 25.4 mm in length and the physical properties of hemp specimen were measured before the compression tests. The outer diameter of hollow hemp stalk varied from 6 to 17 mm; the inner diameter varied from 3 to 8 mm; the linear density varied from 10 to 37 g m -1 . The diameters and linear density were greater at lower height regions of specimen. Specimens were compressed by a computer-aided laboratory scale compression apparatus both in axial and lateral directions of hemp stem. The force-displacement curve was recorded. The maximum compressive load at stem failure, stem modulus and energy requirement for compression were derived from the curve. The results showed the maximum compressive strength, modulus and energy requirements were significantly differ at different hemp height regions and were increased with increasing stalk diameters. In general, higher strength, modulus and more energy required for compression of the lower height region of hemp stalk both in axial and lateral directions of stem

Impact of ethanol and NaCl on the acid yellow dye mediated self-aggregation of sodium dodecyl sulfate: A combined investigation by conductivity and molecular dynamics simulation

•The aggregation behavior of SDS in acid yellow dye with additives is investigated.•The cmc values are dependent on the additive’s composition and temperature.•The aggregation of AY + SDS mixture is obtained to be spontaneous for all systems.•Hydrophobic and electrostatic interactions between AY and SDS are noticed.•MD simulation displays that SDS micelle is more stable in NaCl than water/ethanol media. Herein, we report the micellization behavior of the mixture of sodium dodecyl sulfate (SDS), and acid yellow (AY) dye in water, water + ethanol, and water + NaCl media. The degree of interaction between SDS and AY has been assessed quantitatively from the estimated values of critical micelle concentration (cmc). Three cmc values were observed for the AY + SDS systems at each temperature and solvents utilized, which exhibit a reversed U-shaped variation with respect to the change of temperature in aqueous/NaCl solution while increased monotonically in ethanolic medium almost in all cases. The extent of micellization was found to be disfavored in presence of AY dye. The micellization was also found to be disfavored up to 15% ethanol and favored in the addition of electrolyte species. The values of counterion binding were found to be temperature dependent. The Gibbs free energy (ΔGmo), which was found negative, reveal a spontaneous micellization of AY + SDS system. The other thermodynamic parameters, like enthalpy (ΔHmo) and entropy (ΔSmo) of micellization along with different transfer energies, were also assessed to have an insight on the mode of interaction of surfactant and dye assemblies. The molecular level interaction between SDS and AY has been unveiled by Molecular Dynamics (MD) simulation and exhibits good agreement with experimental results