Sherely Annie Paul  Charlie Oommen  Kuruvilla Joseph  Gem Mathew  Sabu Thomas 《Polymer Composites》2010,31(6):1113-1123

The thermal degradation behavior of banana fiber and polypropylene/banana fiber composites has been studied by thermogravimetric analysis. Banana fiber was found to be decomposing in two stages, first one around 320°C and the second one around 450°C. For chemically treated banana fiber, the decomposition process has been at a higher temperature, indicating thermal stability for the treated fiber. Activation energies for thermal degradation were estimated using Coats and Redfern method. Calorific value of the banana fiber was measured using a constant volume isothermal bomb calorimeter. Crystallization studies exhibited an increase in the crystallization temperature and crystallinity of polypropylene upon the addition of banana fiber. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers  相似文献   

    

J Jegan Roy  T Emilia Abraham 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(11):1836-1839

Cross‐linked enzyme crystals (CLEC) of laccase were prepared by crystallizing laccase with 75% (NH₄)₂SO₄ and cross‐linking using 1.5% glutaraldehyde. The cross‐linked enzyme crystals were further coated with 1 mmol L^?1 β‐cyclodextrin by lyophilization. The lyophilized enzyme crystals were used as such for the biotransformation of pyrogallol to purpurogallin in a packed‐bed reactor. The maximum conversion (76.28%) was obtained with 3 mmol L^?1 pyrogallol at a residence time of 7.1 s. The maximum productivity (269.03 g L^?1 h^?1) of purpurogallin was obtained with 5 mmol L^?1 pyrogallol at a residence time of 3.5 s. The productivity was found to be 261.14 g L^?1 h^?1 and 251.1 g L^?1 h^?1 when concentrations of 3 mmol L^?1 and 7 mmol L^?1 respectively were used. The reaction rate of purpurogallin synthesis was maximum (2241.94 mg purpurogallin mg^?1 CLEC h^?1) at a residence time of 3.5 s, when 5 mmol L^?1 pyrogallol was used as the substrate. The catalyst to product ratio calculated for the present biotransformation was 1:2241. The CLEC laccase had very high stability in reuse and even after 650 h of continuous use, the enzyme did not lose its activity. Copyright © 2006 Society of Chemical Industry  相似文献   

    

Roger Clough  Mathew Celina 《乙烯基与添加剂工艺杂志》2008,14(1):1-2

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G. Mathew  J. M. Rhee  C. Nah  D. J. Leo 《Polymer Engineering and Science》2006,46(10):1455-1460

This article describes the effects of silicone rubber (SR) networks on the actuating behavior of acrylate rubber (AR)‐based dielectric actuators. SR chains were diffused into a swollen AR networks in the presence of a co‐solvent, and then the silicone chains were chemically crosslinked in an attempt to form an interpenetrating polymer network. The presence of SR in the AR network was confirmed by various instrumental analyses including attenuated total reflectance‐Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The total crosslink density based on a swelling method and tensile properties increased with modification time. The Maxwell stresses were also determined using a pure‐shear specimen. They increased in a parabolic fashion with the applied voltage, and depended on the type of compliant electrode and SR used. POLYM. ENG. SCI. 46:1455–1460, 2006. © 2006 Society of Plastics Engineers.  相似文献   

    

MG Gigimol  Beena Mathew 《Polymer International》2003,52(6):973-980

Poly(N‐vinylpyrrolidone)s with 2–20 mol% DVB, NNMBA, HDODA and TTEGDA crosslinkings were prepared by suspension polymerisation. The binding of Rose Bengal by these poly(N‐vinylpyrrolidone)s was followed by a batch equilibration method. In order to optimise the conditions of dye binding, the effect of the concentration of Rose Bengal solutions, temperature and pH were followed. Kinetic studies showed that the binding of Rose Bengal by poly(N‐vinylpyrrolidone)s is a phase boundary process followed by a three‐dimensional diffusion. Copyright © 2003 Society of Chemical Industry  相似文献   

    

Gustavo A. Abraham  Kemal Kesenci  Luca Fambri  Claudio Migliaresi  Alberto Gallardo  Julio San Romn 《大分子材料与工程》2002,287(12):938-945

Poly(methyl methacrylate)‐poly(ε‐caprolactone) (PMMA/PCL) microparticles were synthesized by suspension polymerization of methyl methacrylate in the presence of PCL. The incorporation of a small amount of a macromonomer, methacryloyl‐terminated PCL (M‐PCL), into the reaction mixture, led to the formation of grafted systems, namely PMMA‐g‐PCL/PCL. The synthesis of the macromonomer and its characterization by nuclear magnetic spectroscopy (¹H NMR) is described. The role of M‐PCL as an effective compatibilizing agent in the composite was investigated. PMMA/PCL and PMMA‐g‐PCL/PCL composites were fully characterized by ¹H NMR, gel permeation chromatography (GPC) and thermal analysis, including thermogravimetric analysis (TGA), conventional differential scanning calorimetry (DSC), modulated DSC (MDSC) and dynamic mechanical thermal analysis (DMTA). Finally, the morphology of the prepared systems was investigated by scanning electron microscopy (SEM). The addition of compatibilizing agent led the formation of a more homogeneous microcomposite with improved mechanical properties.

SEM picture of PMMA‐g‐PCL/PCL composite surface.  相似文献   

    

Elizabeth K. Abraham  Anju Francis  P. Ramesh  Roy Joseph 《应用聚合物科学杂志》2001,82(9):2342-2346

The calcium salt of p‐aminobenzoic acid [p‐ABA(Ca)] was reacted with epichlorohydrin to yield the multifunctional epoxy resin. The epoxy resin was characterized by IR spectroscopy, epoxy equivalent, calcium estimation, high performance liquid chromatography (HPLC) and refractive index. The epoxy resin was further reacted with methacrylic acid to yield the calcium containing methacrylate resin, which was characterized by IR, hydroxyl value, iodine value, HPLC and refractive index. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2342–2346, 2001  相似文献   

    

Abdul Rehman Khan  Yousef M. Al-Roomi  Johnson Mathew  Majed Sari 《应用聚合物科学杂志》2001,82(10):2534-2543

Homopoly(amides) similar to those of liquid crystalline poly(oxybenzoate) were prepared by acidolysis of the monomer p-acetamidobenzoic acid. The kinetics of catalyzed and uncatalyzed acidolysis of the 4-acetamidobenzoic acid were investigated at 265, 275, and 285°C. A second-order rate model, which can analyze kinetic parameters of two different kinetic regimes, was used to interpret the experimental data for 18 different experimental sets. It is observed that the correlation coefficient between observed and calculated values range between 0.98 and 0.99, confirming the validity of the stated model. The nature of the kinetic behavior in the two regimes was found to be independent of both catalyst type and concentration. In effect second-order rate law adequately describes the entire kinetic behavior of this system. The Arrhenius constants and activation energy parameters for this system have been reported. Differential scanning calorimetry (DSC) results of the oligomers indicate that the homopoly(amides) melt around 360°C with degradation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2534–2543, 2001  相似文献   

    

G. Kalaprasad  G. Mathew  C. Pavithran  Sabu Thomas 《应用聚合物科学杂志》2003,89(2):432-442

The melt rheological behavior of intimately mixed short sisal–glass hybrid fiber‐reinforced low‐density polyethylene composites was studied with an Instron capillary rheometer. The variation of melt viscosity with shear rate and shear stress at different temperatures was studied. The effect of relative composition of component fibers on the overall rheological behavior also was examined. A temperature range of 130 to 150°C and shear rate of 16.4 to 5470 s^?1 were chosen for the analysis. The melt viscosity of the hybrid composite increased with increase in the volume fraction of glass fibers and reached a maximum for the composite containing glass fiber alone. Also, experimental viscosity values of hybrid composites were in good agreement with the theoretical values calculated using the additive rule of hybrid mixtures, except at low volume fractions of glass fibers. Master curves were plotted by superpositioning shear stress and temperature results. The breakage of fibers during the extrusion process, estimated by optical microscopy, was higher for glass fiber than sisal fiber. The surface morphology of the extrudates was analyzed by optical and scanning electron microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 432–442, 2003  相似文献   

    

Abraham Tamir 《加拿大化工杂志》2000,78(4):847-847

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