Effect of molding condition and pellets material on the weld property of injection molded jute/polylactic acid

Natural fibers such as jute fiber and biodegradable poly(lactic acid) (PLA) polymer are very good choices for environmental friendly material. Multi‐gate injection is often used to meet the demand of mass production of injection moldings, therefore weld line is inevitable. The presence of weld lines not only detracts from the surface quality but also significantly reduces the mechanical strength of injection‐molded parts. Although it is not always easy to completely eliminate weld lines, the weld strength could be improved through suitable adjustment of molding conditions such as melt temperature, mold temperature, hold pressure, injection speed, and so on. In this study, three kinds of pellets materials were prepared: long fiber pellets (LFT), the re‐compounding pellets (RP), and LFT50:RP50 hybrid mixtures (LFT/RP). Tensile test was carried out to investigate the effect of different pellets and holding pressures on the mechanical property of welded jute/PLA specimens. And the interfacial shear strength of non‐welded jute/PLA specimens was calculated with Kelly‐Tyson Formula. Fiber separation and fiber dispersion in RP became better than that of LFT which resulted in a better interfacial property. Weld strength of RP and hybrid LFT/RP specimens was improved by 43.34% and 16.46% than that of LFT specimen, respectively. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Liquid-phase photocatalytic degradation over tio2 particles suspending in gas-liquid dispersion

The photocatalytic degradation over TiO2 particles suspending in the gas-liquid dispersion was modeled by taking the decay of the illumination intensity in the gas-liquid-solid fluidized bed in terms of Lambert-Beer law into consideration. For the sake of experimental verification of the proposed model, the oxidative degradation of an acid dye (C.I. Acid Blue 40) as a model compound, was carried out using a coaxial double cylinder-type reactor (internal cylinder part: quartz glass cylinder installing black light type fluorescent tube as UV light source; annular part: gas-liquid-solid fluidized bed) newly manufactured here. The reactor is operated continuously with respect to the gas phase and batchwise with respect to the solid phase, whereas the liquid phase is recirculated. The degradation rate could be expressed apparently as first-order in the concentration of acid dye. The observed relationship between apparent degradation rate constant and solid (TiO2) loading could satisfactorily be interpreted in terms of the proposed model.     

A Unique Approach to Characterization of Sol‐Gel‐Derived Rare‐Earth‐Doped Oxyfluoride Glass‐Ceramics

Using the sol‐gel route Nd³⁺‐doped oxyfluoride glass‐ceramics were prepared. LiYF₄ and YF₃ crystals were deposited in the glass‐ceramics and their size, distribution, and amount ratio were varied by changing the compositions and heating temperatures. The incorporation of Nd³⁺ ions into both the fluoride crystals was confirmed by the high‐resolution elemental mapping of the glass‐ceramics. The incorporated Nd³⁺ ions showed up and down conversion photoluminescence whose properties were obviously different among the samples. The preliminary site analysis for Nd³⁺ ions was carried out using a unique approach associated with the Prony series approximation. Finally, the approach was found to be useful for the analysis of materials that are structurally complicating.     

ADDUCT FORMATION OF β-DIKETONATO LANTHANOIDS(III) WITH CARBOXYLIC ACIDS HAVING HYDROXYL AND METHOXYL GROUPS

Adduct formation of 2-thenoyltrifluoroacetonato(tta) lantha-num(III), europium(III), and ytterbium(I II) with α-pheny 1 1 actic, α-methoxy phenyl acetic, salicylic, and o-methoxy benzoic acids in chloroform has been studied by solvent extraction technique. It has been found that 1anthanoid(111) chelates form more stable adducts with these carboxylic acids in the sequence: Yb(tta)₃ < Eu(tta) ₃ < La(tta) ₃. The adduct formation constants as well as the separation factors obtained as the ratio of the constants between a pair of metals are the largest for α-phenyl lactic acid among these acids. The characteristics with α-phenyl 1actic acid would be caused by the action as bidentate unlike benzoic acid derivatives which work as monodentates owing to the internal complexa-tion through hydrogen bonding.     

The preparation,swelling characteristics,and albumin adsorption and release behaviors of a novel chitosan-based polyampholyte hydrogel

A novel chitosan (Ch)-based polyampholyte hydrogel was prepared from Ch dissolved in a 1:1 (v/v) mixture of 10% aqueous acetic acid and N-methyl-2-pyrrolidinone (NMP) by simple crosslinking using 1,2,3,4-butanetetracarboxylic dianhydride (BTCA). The detailed structure of the hydrogel was determined via FTIR and solid-state ¹³C NMR spectroscopic analyses. The swelling behavior of the hydrogels was strongly dependent on the BTCA feed ratio, and the hydrogels exhibited a pH-responsive swelling ratio that was influenced by the presence of both cationic NH₃⁺ and anionic COO^? groups within their molecular structures. The Ch hydrogels also exhibited bovine serum albumin (BSA) adsorption capacity, which was maximal at pH 4.5, consistent with the isoelectric point of BSA (4.7). In addition, the BSA adsorption capacity of the hydrogel decreased with the increasing ionic strength of the adsorption medium, indicating that the capacity of the hydrogel to adsorb BSA is facilitated by hydrophobic as well as electrostatic interactions between the hydrogels and the BSA molecules. In addition, a high desorption ratio (89%) of BSA was achieved in aqueous solutions at pH 2.0.     

A Preliminary Investigation of the ISG Glass Vapor Hydration

During the geological disposal of high-level waste, the nuclear glass is expected to be first hydrated in water vapor prior to liquid alteration. In the present work, we investigated the vapor hydration of the International simple glass (ISG) at 175°C and different relative humidities (60%, 80% and 98%). The glass hydration was investigated by nuclear reaction analysis (NRA) and Fourier transform infra-red spectroscopy. The chemical and mineralogical compositions of the alteration products were studied using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) and μ-Raman spectroscopy, respectively. The NRA results gave water diffusion coefficients of 2.31–7.34 × 10⁻²¹ m²/s_, in good agreement with the literature data on borosilicate glasses altered in aqueous media. The glass hydration increased with relative humidity percentage and the SEM-EDS analysis showed a slight enrichment in Si and loss of Na in the hydrated glass layer compared with the pristine glass. The hydration rate of the ISG glass was little higher than that of the French SON68 glass hydrated using water vapor. The corrosion products were analcime, tobermorite, and calcite, which were typical of the SON68 glass hydrated in similar conditions.     

Round robin on indentation fracture resistance of silicon carbide ceramics by using a powerful optical microscope

Reproducibility of indentation fracture resistance, K_IFR of silicon carbides sintered with B and C was evaluated by a round robin with ten laboratories. When the crack length was measured with an optical microscope at a low magnification of ～100×, K_IFR varied widely from 3.43 to 4.20 MPa m^1/2, whereas those obtained by a powerful microscopy with both an objective lens of 40× and a traveling stage exhibited a consistent value of 3.20±0.12 MPa m^1/2. The wide scatter of K_IFR for the former measurements was attributed mainly to the variation in misreading of the crack length. It was revealed that the high resolving power of the objective lens of 40× enabled to find exact crack tips easily, which resulted in the good matching of K_IFR between laboratories for the latter case. It was suggested that the observation of indentations with powerful optics was effective for improving the reproducibility of the IF method.     

Preparation of thermally stable polymer electrolytes from imidazolium-type ionic liquid derivatives

Thermally stable polymer electrolytes based on ionic liquids were prepared and analyzed. Mono-functional ionic liquid monomers, ionic liquid cross-linkers, and ethylimidazolium-type ionic liquid salts were mixed and polymerized. The ionic liquid-type cross-linkers were effective to prepare thermally stable polymer films. In particular, the copolymerization of cross-linker and ethylimidazolium-type ionic liquid monomers were used to make polymer electrolytes with high ionic conductivities. The copolymerization in ethylmethylimidazolium bis(trifluoromethanesulfonyl)imide gave a transparent film showing no thermal degradation up to 400 °C.     

The effect of heat sealing temperature on the properties of OPP/CPP heat seal. I. Mechanical properties

The effect of heat sealing temperature on the mechanical properties and morphology of OPP/CPP laminate films was investigated. The laminated films were placed in an impulse type heat sealing machine with both CPP sides facing each other. The temperatures investigated ranged from 100 to 250°C. T‐peel and tensile tests in combination with SEM were used to characterize the heat seals. A minimum seal initiation temperature of 120°C was identified for OPP/CPP laminate heat sealing. Peel strength increased sharply from zero at 110°C to maximum at 120°C, after which a gradual decrease was observed. Tensile strength initially increased until 120°C, after which it gradually decreased until 170°C and assumed a constant value beyond that. The initial rise has been associated to cold crystallization, while the reduction between 120°C and 170°C was due to relaxation in molecular orientation. Beyond 170°C, all the orientation in the laminate has been lost so orientation effects are nullified. Morphological studies with SEM revealed that seals were partially formed at lower temperatures, while the laminates were totally fused together at high temperatures, with intermediate temperatures showing properties that lie in between. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 753–760, 2005