Impregnation of silk sericin into polyester fibers using supercritical carbon dioxide

Silk sericin was impregnated into polyester fabric using supercritical carbon dioxide (SCCO₂) to overcome polyester hydrophobicity. The effects of sericin molecular weight, pH of sericin, solution and cosolvent types on sericin impregnation were investigated. Enzyme‐hydrolyzed, acid‐, based‐hydrolyzed sericin in SCCO₂, and a 30 kDa sericin in SCCO₂ modified with cosolvents such as water, methanol, 1‐propanol, and acetone; and a modifier: sodium hydroxide solution were used in this work. Impregnation of sericin in polyester was indicated by Fourier transform infrared spectrophotometry (FTIR) and dyeing with acid dye. Degradation of polyester fibers during SCCO₂ process was indicated by scanning electron microscopy (SEM). Methylene blue dyeing was used to realize carboxyl group in polyester. The results showed no impregnation of sericin into polyester by using SCCO₂ modified with cosolvents. However, sericin was impregnated into modified surface polyester since hydrophilic groups such as carboxyl and hydroxyl groups were regenerated by alkaline hydrolysis. Samples impregnated with hydrolyzed sericin showed high color strength of Supranolechtbordeaux B acid dye. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Numerical Study of the Effects of the Secondary Diaphragm and Contact Surface in Expansion Tubes

The interaction of the shock reflected at a secondary diaphragm with the primary contact in six cases, i.e. the strengths and shapes of the contact surface are different, were explored by numerical study. The influences of the strength and shape of the contact on the developing wave pattern and the quality of the test gas are illustrated by many kinds of figures (e.g. the time-distance diagrams of the acoustic impedance contours on the axis, the acoustic impedance contours, and the time histories of pilot and static pressures).     

Fibrillation tendency of cellulosic fibers,part 6: Effects of treatments with additive polymers

The influences of the treatments with various polymers on fibrillation and abrasion resistances of lyocell materials were investigated with respect to the type of polymer, the polymer concentration, and the drying temperature. Fibril number, generated with agitation using ball‐bearings (FN_ball), was decreased with increasing the concentration of aminofunctional polysiloxane because of reduction in water retention capacity (WRV) in fibers. The never‐dried lyocell fiber showed smaller decrease in FN_ball because of its higher WRV when compared to dried fibers. The treatment with aminofunctional polysiloxane enhanced not only the fibrillation resistance but also abrasion resistance, which was indicated as rotation number of abrasive bar in the abrasion test (RN_abr). No fibrillation was obtained in the fiber treated with 10 g/L aminofunctional polysiloxane at 120°C for 20 min, while the fibers treated at 60 and 170°C for 15 min were fibrillated in the agitation and abrasion tests. The addition of secondary polyethylene derivative also reduced the fibrillation tendency of lyocell; however, the extent of the reduction was lesser when compared with aminofunctional polysiloxane. The treatments with polyacrylate, polyurethane, and polyisocyanate derivatives improved the fibrillation resistance in lyocell fabrics, while fiber abrasion resistance was not significantly improved by the treatment with those additives, except in polyisocyanate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4140–4147, 2006     

Enhancing oil repellency of electron beam-grafted polyethylene terephthalate fabric with 2-(perfluorohexyl) ethyl acrylate monomer via pre-irradiation

Electron beam (EB)-induced graft polymerization is advantageous for the surface modification of fabrics. We investigated the effect of monomer concentration and the addition of alkyl groups on the oil repellency of polyethylene terephthalate (PET) fabrics treated with monomers containing fluoroalkyl groups through EB-induced graft polymerization via pre-irradiation. We use 2-(perfluorohexyl) ethyl acrylate (FEA) and stearyl acrylate (SA(C18)) with long alkyl chains as vinyl monomers to induce reaction with radicals generated from EB irradiation. The weight gain and surface morphology of the PET fabrics change with the FEA monomer concentration. The uniformity of the EB-grafted PET fabric surface is determined at low monomer solution concentrations. Results of X-ray photoelectron spectroscopy analysis show that adding 0.1 mol/L of FEA monomer to the EB-grafted PET fabric yields the highest dodecane contact angle of 93.4° and a surface fluorine concentration of 39.8%. The addition of SA(C18) monomer to the FEA monomer decreases the dodecane contact angle by 77.5° and yields a surface fluorine concentration of 19.1%. EB graft polymerization via pre-irradiation results in a uniformly treated surface, and stable oil repellency is achieved when using solely the FEA monomer at a lower monomer concentration than that used in a similar irradiation method reportedly previously.     

Preparation of cellulose triacetate aerogel via non-solvent impacted thermally induced phase separation for oil absorption

The oil spill has caused significant attention on a global scale due to its damage to the environment and the economy. The development of economically and ecologically friendly oil sorbent materials has important meaning for the oil spill concern. In this work, we explored the non-solvent impacted thermally induced phase separation (NITIPS) method to prepare the cellulose triacetate aerogel (CA) with low density (6.4–40.5 mg/cm³), high porosity (96.9–99.5%), large water contact angle (>129°) and high specific surface area (193–573 m²/g) as the oil sorbent material. The oil absorption capacity of CA with vegetable oil and vacuum pump oil reached 80.8 g/g and 38.9 g/g, respectively, consistent with Fick's law of diffusion. Moreover, the NITIPS method provided simpler process and controlled the shape of CA compared with the traditional thermally induced phase separation method. This study proved that the CA prepared by NITIPS methods played an important role as a potential oil absorption solids in the field of oil spill and organic chemical leakage.     

Effects of cyclodextrin on the electrolytic reduction of an anthraquinone dye

The electrochemical property of a water-soluble anthraquinone, CI Acid Blue 25, was investigated in the presence of · -, ·· - or ·-cyclodextrin. Addition of cyclodextrin (CDx) reduced the redox potential of the dye in the order: · - > ·- > ·-CDx. Cyclic voltammography confirmed this behaviour. The suppression of the electrolytic reduction of the dye indicated that ·- or ·-CDx interacted with it more than ·-CDx. Spectrophotometric analysis also showed that ·-CDx was capable of forming a complex with the dye. In addition, the electrolytic reduction improved the uptake of dye by nylon 6 in the presence of CDx.     

A simplified measurement of adhesion between p-aramid fiber and polypropylene

It is well known that p-aramid fiber is difficult to reinforce the polypropylene (PP) matrix with high adhesion. In addition, the conventional adhesion measurements were always extremely inconvenient. Therefore, it is necessary to simplify the adhesion measurement and also produce a p-aramid/PP composite with high adhesion. In this work, “Bundled filaments pull out (BFPO)” method as a simplified measurement was applied to measure the adhesion properties of p-aramid fiber/PP composite. The suitable processing parameters of the p-aramid fiber/PP composite preparation were also discussed from BFPO test results. Feasibility of this BFPO method was examined through comparing the tendency of adhesion between p-aramid fiber and PP by BFPO method and micro-droplet method. The resultant p-aramid fiber/PP composite prepared at 180°C with a 3?mm embedded length showed a high degree of PP impregnation. The adhesion tendency of p-aramid fiber/PP composites was mainly the same when comparing the results using BFPO method and micro-droplet method.     

Fibrillation tendency of cellulosic fibers. VII. Combined effects of treatments with an alkali,crosslinking agent,and reactive dye

Lyocell woven fabrics were treated with crosslinking agents [1,3‐dimethyl‐4,5‐dihydroxyethylene urea (X1) and 1,3‐dimethylol‐4,5‐dihydroxyethylene urea (X2)], binders [polyacrylate (B1), anionic polyacrylate (B2), anionic polyurethane (B3), and aliphatic polyisocyanate (B4)], and polyfunctional reactive dyes in combination with alkali treatments. The effects of the treatment conditions, including the reagent types, the reagent concentrations, the process types (pretreatments or posttreatments with alkali), and the treatment combinations, on the fibrillation tendency and dyeing behavior in treated samples were investigated. Generally, the fibril number decreased with an increasing concentration of additives and decreased further with reactive dyeing. Fabrics treated with 45 g/L X1 (34 g/kg of fiber) or with 28 g/L X2 (21 g/kg of fiber) and dyed thereafter exhibited no fibrillation. Posttreatments with alkalis caused no changes in either the color shade or fibrillation tendency of crosslinked fabrics, although they enhanced the water retention capacity. The use of mixtures of binders B3 and B4 minimized the fibrillation, but the use of B4 led to changes in the color shade. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:1176–1183, 2006     

Numerical Study of Interaction of Propagated Shock with Boundary Layer Behind Contact Surface in Ducts

The interactions of the shock with the boundary layer of the cold gas behind the contact in many different conditions, i.e. three kinds of test gases and three kinds of sound speed ratios across the contact, were explored by numerical study. The trajectories of the transmitted shock in cold gas flow and the development of shock bifurcation in the process of interaction with boundary layer are illustrated by many kinds of figures (e.g. the time-distance diagrams of the acoustic impedance contours on the axis, the pressure and density contours and the static pressure distributions on the axis).     

Moisture sorption/desorption behavior of various manmade cellulosic fibers

The kinetics of dynamic water vapor sorption and desorption on viscose, modal, cotton, wool, down, and polyester fibers and lyocell knit fabrics were investigated according to the parallel exponential kinetics (PEK) model. The total equilibrium moisture regain (M_inf(total)) in all the materials decreased with increasing temperature. However, the partial equilibrium fast sorption, determined by PEK simulation at 60% relative humidity (RH) and 36°C, was larger than that at 20°C, whereas the partial equilibrium slow sorption was smaller. The characteristic times in fast sorption (τ₁) and in slow sorption (τ₂) for lyocell were reduced when the conditions were changed from 60% RH and 20°C to 36°C, whereas those for the other fibers increased. Lyocell exhibited the highest M_inf(total) value and the lowest τ₁ and τ₂ values, and this suggested high equilibrium moisture content and fast moisture uptake/release, that is, high moisture accessibility for lyocell. The relationships between the moisture regain, hysteresis, water retention capacity, and Brunauer–Emmett–Teller surface volume in the materials were also examined. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1621–1625, 2005