Absorption plasticization of alumina сeramic fiber

The dependence of tensile strength and elongation at failure strain on the change in oiling-emulsion concentration was studied. A correlation between the tensile strength and elongation values at failure strain with the change in the surface activity and specific electrical conductivity of the oiling emulsion was observed with a change in the oiling-emulsion concentration from 2 to 20%. This indicates that electro-physical processes play an important role in the adsorption mechanism: free electrical charges on the fiber surface under mechanical loading.     

Correlation of polymer-like solution behaviors with electrospun fiber formation of hydroxypropyl-β-cyclodextrin and the adsorption study on the fiber

In this paper, the formation of hydroxypropyl-β-cyclodextrin (HPCD) nanofibers in electrospinning and the adsorption of organic molecules on the HPCD nanofiber were studied. The properties of a polymer-like solution from the highly concentrated HPCD/N,N-dimethylformamide (DMF) solution revealed HPCD supramolecular aggregates formation. The entanglements of HPCD self-organized aggregates were one of the most important factors that significantly influenced fiber formation during cyclodextrin electrospinning. The HPCD self-organized aggregates entanglement concentration (C(e)) was investigated. Analyzing the dependence of specific viscosity (η(sp)) on concentration enabled the determination of the aggregates unentangled and entangled regimes for HPCD polymer-like solutions. The dynamic light scattering (DLS) measurements and the (1)H NMR spectra of the HPCD solutions confirmed the presence of considerable HPCD self-organized aggregates in high concentrated HPCD/DMF solutions due to the intermolecular hydrogen bonding. The scanning electron microscopy (SEM) showed the electrospinning morphology transitioned from regular beads to uniform fibers with increasing the HPCD concentration. The dependence of the fiber diameter on the zero shear rate viscosity (η(0)) was determined. The static adsorption behavior of the HPCD fibers was studied. Neutral red (NR) was used as a model organic molecule. The adsorption of NR onto HPCD fibers fitted the pseudo-second-order kinetic model. The equilibrium adsorption amount of NR was 18.41 mg g(-1), and the apparent adsorption rate constant was 9.83 × 10(-4) g mg(-1) min(-1) at 25 °C.     

Thermal analysis kinetics of thermal decomposition of nickel–viscose composite fiber

In this study, the thermal decompositions of nickel composite fibers (NCF) under different atmospheres of flowing nitrogen and air were investigated by XRD, SEM–EDS, and TG–DTG techniques. Non-isothermal studies indicated that only one mass loss stage occurred over the temperature regions of 298–1,073 K in nitrogen. The mass loss was from the decomposition. But after this decomposition, nickel was oxidized in air, when the temperature was high enough. In nitrogen media, the model-free kinetic analysis method was applied to calculate the apparent activation energy (E _a) and pre-exponential factor (A). The method combining Satava–?esták equation with one TG curve was used to select the suitable mechanism functions from 30 typical kinetic models. Furthermore, the Coats–Redfern method was used to study the NCF decomposition kinetics. The study results showed that the decomposition of NCF in nitrogen media was controlled by three-dimension diffusion; mechanism function was the anti-Jander equation, the apparent activation energy (E _a) and the pre-exponential factor (A) were 172.3 kJ mol^?1 and 2.16 × 10⁹ s^?1, respectively. The kinetic equation could be expressed as following: $$ \frac{{{\text{d}}\alpha }}{{{\text{d}}T}} = \frac{{ 2. 1 6\times 1 0^{ 9} }}{\beta }{ \exp }\left( {\frac{ - 2 0 7 2 4. 1}{T}} \right)\left\{ {\frac{ 3}{ 2}(1 + \alpha )^{2/3} [(1 + \alpha )^{1/3} - 1]^{ - 1} } \right\}. $$      

Evolution of the composition and structure of PAN carbon fiber during preoxidation

Using scanning electronic microscope, X-ray diffraction analysis, PYR-GCMS and IR etc., we studied the evolving process of the composition and structure of PAN carbon fiber during preoxidation. In the initial stage of preoxidation, PAN filament tows disappear and become semi-thaw. At first, reactions happen between the copolymers and esters disappear. The molecules annularly crosslink and the index of cyclation slowly increases. It is easy to fix the structure and form defects during the initial and the medium stages, which are most reactive. More traction is advised in these stages to minimize the structural deficiencies. In the medium stage of preoxidation, the fiber was reshaped into new sheet stacks and gradually changed to sheet sectors, and this structure tends to be stable in the final stage. Induced by acid and ester copolymer, PAN fiber forms a very stable cycle structure in the final stage. Besides, monomer, dimmer and trimer obviously decrease. In the final stage of the preoxidation, there exi     

Synthesis of polypiperazine-amide thin-film membrane on PPESK hollow fiber UF membrane

A new interfacial polymerization (IP) procedure is developed in order to synthesize polypiperazine-amide thin-film membrane on the inner surface of poly(phthalazinone ether sulfone ketone) (PPESK) hollow fiber ultrafiltration (UF) membrane.A hollow fiber composite membrane with good performance was prepared and studied by FT-IR and scanning electron microscopy.     

Analytical characterization of cell–asbestos fiber interactions in lung pathogenesis

Asbestos is a fiber causing lung diseases such as asbestosis and mesothelioma. Although the process involving these diseases remains to be elucidated for developing drugs and treatments, direct consequences of fiber exposure in humans have been clearly demonstrated. These diseases are first characterized by histological heterogeneity and combine chronic inflammation with fibrosis and cellular alterations. As a consequence, asbestosis is usually diagnosed at advanced stages of the disease and treatments are usually inefficient to cure the patients. Here, we review the links established between asbestos fiber chemistry and morphology with the occurrence of associated lung diseases. Cytological and histological aspects of diseases are described with respect to current analytical capabilities, notably for microscopy techniques.     

Immobilization of α-amylase from Bacillus circulans GRS 313 on coconut fiber

A simple and inexpensive method for immobilizing alpha-amylase from Bacillus circulans GRS 313 on coconut fiber was developed. The immobilization conditions for highest efficiency were optimized with respect to immobilization pH of 5.5, 30 degrees C, contact time of 4 h, and enzyme to support a ratio of 1:1 containing 0.12 mg/mL of protein. The catalytic properties of the immobilized enzyme were compared with that of the free enzyme. The activity of amylase adsorbed on coconut fiber was 38.7 U/g of fiber at its optimum pH of 5.7 and 48 degrees C, compared with the maximum activity of 40.2 U/mL of free enzyme at the optimum pH of 4.9 and 48 degrees C. The reutilization capacity of the immobilized enzyme was up to three cycles.     

Glass fiber reinforced composites of phenolic–urea–epoxy resin blends

The present work aims to modify conventional epoxy resin by blending with four different phenolic–urea oligomers. These oligomers are similar to phenolic–urea resin matrix and simultaneously function as amino curing agent for epoxy matrix. In this context, phenolic–urea oligomers were prepared respectively by polycondensation reaction of four phenols namely phenol, m-cresol, resorcinol and 1,5-dihydroxy naphthalene, respectively with formaldehyde and urea in presence of acid catalyst. The resulting oligomers were characterized by elemental analysis, spectral studies (IR & NMR), number average molecular weight $(\overline{M}n)$ estimated by non-aqueous conductometric titration and thermal stability by thermogravimetric analysis (TGA). Each of these oligomers was used in resin matrix as a blending component for the modification of commercial epoxy resin for fabricating glass fiber reinforced laminates. Finally these laminates were evaluated for their synergetic thermal stability, mechanical properties and chemical resistance to different reagents.     

Effect of surface treatments on the dynamic mechanical behavior of piassava fiber–polyester matrix composites

The effect of several fiber surface treatments upon the dynamic mechanical behavior of piassava fiber-reinforced composites was evaluated. In the light of the experimental results obtained the critical volume fraction for the fibers to effectively perform as reinforcement was established. The results show that all treatments performed (mercerization, acetylation, and mercerization + acetylation) enhance the fiber/matrix adhesion, but some treatments also affect the fiber’s integrity. At the elastic region the storage modulus of the composites fabricated with treated fibers was higher than that of the untreated fiber-reinforced composite. However, only the composite manufactured with 10 wt% mercerized fibers showed a statistically significant increase of the storage modulus. Above T _g the storage modulus was primarily governed by the volume fraction of fibers. Therefore, raw and treated fiber composites had essentially the same behavior.     

What is dietary fiber?

Dietary fiber consists of the remnants of the edible plant cell, polysaccharides, lignin, and associated substances resistant to digestion (hydrolysis) by human alimentary enzymes. This physiological definition has been translated into a chemical method (AOAC Method 985.29), which has recently been shown to miss substances of 10, 11, and 12 degrees of polymerization. It also fails to precipitate some hydrolysis-resistant oligosaccharides which contain many physiological properties expected in dietary fiber, such as inulin and oligofructose, indigestible dextrin (Fibersol-2), galactooligosaccharides and the synthetic polymer polydextrose. The Executive Board of the American Association of Cereal Chemists has appointed a committee to explore the possibility of expanding the definition or chemical methodology for dietary fiber to accommodate components that are not hydrolyzed by human alimentary enzymes, yet have the physiological attributes normally associated with dietary fiber. However, the present review suggests that the current definition is sufficient, along with new methodology, to detect recently discovered components of the dietary fiber complex.     

Synthesis of new N-alkylsulfonamide-containing phenylazopyrazolone dyes and their application to unmodified polypropylene fiber

Three new N-alkylsulfonamide-containing phenylazopyrazolone dyes have been synthesized by reaction of sulfonyl chloride intermediates with different saturated aliphatic amines and their molecular structures were confirmed by FTIR,~1H NMR and MS. The dyes were applied to unmodified polypropylene fabric.These dyes showed high exhaustion as well as higher levels of fastness to washing,sublimation and rubbing compared with C.I.Disperse Yellow 16.The results showed the N-alkylsulfonamide- containing dyes were suitable for dyeing unmodified PP fiber and exhibited good color depth and fastness properties.     

Kinetics of fiber impregnation by a binder. Gradient generalization of Navier–Stokes–Darcy equations

A model of polymer composition material that is composed of a unidirectional fiber and binder has been considered. The space between two neighboring filaments of fibers is considered as a capillary along which the binder propagates during impregnation. In order to describe the flow process, a gradient generalization of the Navier–Stokes equation has been suggested. A corrected model of the flow of binder in the capillary-porous space of a unidirectional fiber material is developed on its basis. In particular cases, the found solution coincides with the Navier–Stokes–Darcy equations and conventional Navier–Stokes equation. The model that has been developed allows the refinement of the nonclassical effect of the existence of two boundary layers that appear during flow and may prevent it.     

Preparation of new base-aluminum-chloride-loaded fiber as adsorbent for fast removal of arsenic(Ⅴ) from water

A new base-aluminum-chloride-loaded fiber[PET-AA-NN-Al₂（OH）_nCl_6-n]was prepared with polyethylene glycol terephthalate （PET） as adsorbent for fast removal of arsenic（Ⅴ） from water.This new fibrous adsorbent was characterized by using SEM and C NMR spectroscopy.Adsorption kinetic curve indicated that this new fibrous adsorbent could fast remove arsenic（Ⅴ） from water, and adsorption isotherm also indicated that PET-AA-NN-A1₂（OH）_nC1_6-n had high equilibrium adsorption capacity for arsenic（Ⅴ）.     

Study on formation of poly(β-hydroxybutyrate-co-hydroxyvalerate) (PHBV) fiber

In this paper, the crystallization behavior, thermal degradation properties, rheological behavior and the spinnability of poly(β-hydroxybutyrate-co-hydroxyvalerate) (PHBV) fiber were studied. Experimental results indicated that the spherulite growth rate of PHBV was very slow and its size was very large. PHBV began to degrade above 170°C. The flowing curve indicated that the processing temperature and the residential time had important effects on PHBV melts. When the equipment of melting spinning was improved and processing conditions were strictly controlled, the mechanical properties of the PHBV filament can comply with the requirements of the American Pharmacopoeia. __________ Translated from Journal of Donghua University (Natural Science Edition), 2007, 33(4): 425–430     

Correlation of fractal pore-size distribution of activated carbon fiber with its adsorption for low concentration benzene vapor

Fractal pore-size distribution K(x) is given based on J(x) function proposed by Jaronic. Activated carbon fibers (ACF) with different surface areas are characterized by using two functions mentioned above. The present work studies the fractal pore-size distribution of ACF and adsorption isotherms of nonpolar benzene vapor on ACF, and thereby reveals the correlation between them.     

Thermal behavior of cardanol resin reinforced 20 mm long untreated bagasse fiber composites

Recently the attention in composite materials reinforced with natural fibers has significantly increased due to the new environmental legislation as well as consumer pressure that forced manufacturing industries to search substitutes for the conventional materials, e.g., glass fibers. In this way, the objective of the paper was to evaluate the thermal properties of sugarcane bagasse fiber-cardanol resin composites. Fibers were cut down to 20?mm length in diagonally. These fibers were mixed with the cardanol and epoxy resin, and fabricate in a biocomposites with different compositions, such as 0, 5, 10, 15, and 20?wt%. The thermal properties were evaluated by thermal gravimetric analysis and differential thermogravimetry analysis and also chemical formulation studied in Fourier transform infrared spectroscopy. The results showed the improved thermal strength of the composites in comparison to the neat polymer (0?wt%).     

Improvement of bagasse fiber–cement composites by addition of bacterial nanocellulose: an inverse gas chromatography study

The design of green fiber-reinforced nanocomposites with enhanced properties and durability has attracted attention from scientists. The present study aims to investigate the potential of bacterial nanocellulose (BNC) as a green additive for fiber–cement composites. Inverse gas chromatography (IGC) was used to evaluate the influence of incorporation of BNC as powder or gel, or coated onto the bagasse fibers, on the fiber–cement composite (FCC) surface. The results indicated that BNC incorporation made the FCC surface more reactive, increasing the dispersive component of the surface energy. The most relevant effects were found for BNC incorporation as gel or coated on the fibers. Incorporation of BNC as gel resulted in a predominantly organic FCC surface with substantial decreased surface basicity (K _a/K _b ratio from 2.88 to 5.75). IGC also showed that FCC with BNC incorporated as gel was more susceptible to hydration. However, BNC coated on fibers prevented fiber mineralization, increasing the inorganic materials at the surface, which caused an increase in the surface basicity (K _a/K _b ratio decrease to 2.00). These promising results could contribute to development of a new generation of green hybrid composites. The IGC technique enabled understanding of the physicochemical changes that occur on deliberate introduction of nanosized bacterial cellulose into fiber–cement composites.     

Preparation and characterization of sol–gel-modified pineapple leaf fiber/polylactic acid composites

In this study, the fibers generated from agricultural waste-pineapple leaf are obtained through exposure, drying, crushing and sifting. A novel sol–gel method is utilized to modify the pineapple leaf fiber (PALF), which is subsequently treated by a coupling agent. The aim is to improve the compatibility between PALF and the polymer matrix and to enhance the heat resistance and mechanical properties of the composite material. Furthermore, a series of modified PALF/polylactic acid (PLA) composites are prepared. FTIR, high resolution solid-state ¹³C and ²⁹Si NMR experiments show that the PALF was successfully modified by the silane coupling agent and sol–gel method. Polarizing optical microscopy analysis reveals PLA crystal growth of a sufficiently high density along the polymer-fiber interface. Moreover, the storage and loss moduli of PLA are increased by adding the modified PALF. Apart from the enhancement of the mechanical properties, the incorporation of modified PALF reduces the amount of agricultural waste and extends the application of PLA.     

Preparation and evaluation of propranolol molecularly imprinted solid-phase microextraction fiber for trace analysis of β-blockers in urine and plasma samples

An improved multiple co-polymerization technique was developed to prepare a novel molecularly imprinted polymer (MIP)-coated solid-phase microextraction (SPME) fiber with propranolol as template. Investigation was performed for the characteristics and application of the fibers. The MIP coating was highly crosslinked and porous with the average thickness of only 25.0 μm. Consequently, the adsorption and desorption of β-blockers within the MIP coating could be achieved quickly. The specific selectivity was discovered with the MIP-coated fibers to propranolol and its structural analogues such as atenolol, pindolol, and alprenolol. In contrast, only non-specific adsorption could be shown with the non-imprinted polymer (NIP)-coated fibers, and the extraction efficiencies of propranolol and pindolol with the MIP-coated fibers were higher markedly than that with the commercial SPME fibers. A MIP-coated SPME coupled with high-performance liquid chromatography (HPLC) method for propranolol and pindolol determination was developed under the optimized extraction conditions. Linear ranges for propranolol and pindolol were 20–1000 μg L⁻¹ and detection limits were 3.8 and 6.9 μg L⁻¹, respectively. Propranolol and pindolol in the spiked human urine and plasma samples, extracted with organic solvent firstly, could be simultaneous monitored with satisfactory recoveries through this method.