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Alcohol Copolymer (alcohol + copolymer)
Kinds of Alcohol Copolymer Selected AbstractsA Palladium Wall Coated Microcapillary Reactor for Use in Continuous Flow Transfer HydrogenationADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Christian Abstract Herein we describe the preparation of a novel continuous flow multi-channel microreactor in which the internal surface has been functionalised with a palladium coating, enabling its use in catalytic heterogeneous liquid-phase reactions. Simple chemical deposition techniques were used to immobilise palladium(0) on the channel wall surface of a polymeric multi-capillary extrudate made from ethylene-vinyl alcohol copolymer. The Pd coating of the microcapillaries has been characterised by mass spectrometry and light and electron microscopy. The functional activity of the catalytic Pd layer was tested in a series of transfer hydrogenation reactions using triethylsilane as the hydrogen source. [source] Rheological, morphological, mechanical, and barrier properties of PP/EVOH blendsADVANCES IN POLYMER TECHNOLOGY, Issue 3 2001Jong Ho Yeo Using the biaxially oriented film process, polypropylene (PP)/ethylene-vinyl alcohol copolymer (EVOH) blends with an improved barrier property could be obtained by generating a laminar structure of the dispersed phase in the matrix phase. This laminar morphology, induced by biaxial orientation, was found to result in a significant increase in the oxygen barrier property of PP/EVOH (85/15) blends by about 10 times relative to the pure PP. In this study, compatibility in the PP/EVOH blend system was evaluated by investigating the influence of compatibilizer on the rheological, morphological, and mechanical properties of the blends. In addition, the effects of compatibilizer content, draw ratio, and draw temperature on the oxygen permeability and morphology of biaxially drawn blend films were also studied. It was revealed that an optimum amount of compatibilizer, maleic anhydride grafted PP, should be used to improve the barrier property of the PP/EVOH blends with a well-developed laminar structure. The draw ratio and draw temperature had a significant influence on the permeability of the blends. The blend films exhibited a more pronounced laminar structure when the blends were stretched biaxially under processing conditions of higher draw ratio and draw temperature, resulting in higher barrier properties. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 191,201, 2001 [source] A simple model for the interaction between water vapour and oxygen transmission in multilayer barrier materials intended for food packaging applicationsPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2008Marianne Jakobsen Abstract The low oxygen permeability of the ethylene-vinyl alcohol copolymer, EVOH, is outstanding, but is also known to be very sensitive to moisture uptake and cannot be used as a monolayer packaging material. In this paper, theory is presented in order to calculate the average water activity of the EVOH layer at steady state and the corresponding oxygen barrier for different multilayer structures using various polymer types and layer thicknesses. Multilayer materials can be designed for different food packaging applications and storage conditions, in order to keep the relative humidity of the barrier below recommended 75%, by varying the thickness of the outside versus the inside protective layers and/or varying the water vapour transmission rate of the outside versus the inside layer. The conclusion reached is that to retain the optimal barrier properties and thereby the optimal protection of the food, asymmetric multilayer structures are necessary. Copyright ©2007 John Wiley & Sons, Ltd. [source] Aging of Plasma-Deposited Films Prepared from Organic MonomersPLASMA PROCESSES AND POLYMERS, Issue S1 2007Sufal Swaraj Abstract Plasma-deposited polymer films were prepared from organic molecules and investigated using near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) for aging effects after exposure to air. Results from the investigation of homopolymers are summarized. Primarily the effect of the deposition parameters duty cycle and power are dealt with. The effect of the deposition parameter pressure is briefly discussed. An example to show the effect of feed gas composition on the aging of plasma polymerized ethylene/allyl alcohol and styrene/allyl alcohol copolymer is also given. In general, change in content of unsaturated or aromatic species, change in concentration of monomer functionality, and change in the oxygen content was observed in the plasma polymerized films on aging. [source] The effect of interface characteristics on the static and dynamic mechanical properties of three-component polymer alloysPOLYMER COMPOSITES, Issue 3 2002I. Fisher The effect of interfacial characteristics on the structure-property relationships of ternary polymer alloys and blends comprising polypropylene (PP), ethylene-vinyl alcohol copolymer (EVOH) and glass beads (GB) or fibers (GF) was investigated. The systems studied were based on a binary PP/EVOH immiscible blend, representing a blend of a semi-crystalline apolar polymer with a semi-crystalline highly polar copolymer. The ternary systems studied consisted of filler particles encapsulated by EVOH, with some of the minor EVOH component separately dispersed within the PP matrix. Modification of the interfacial properties was done using silane coupling agents for the EVOH/glass interface and compatibilization using a maleic anhydride grafted PP (MA-g-PP) for the PP/EVOH interface. Both glass fillers increased the dynamic modulus and decreased the damping of the neat polymers and of their binary blends, especially in the rubbery region. GF has a more profound effect on both the modulus and the damping. Glass surface treatments and compatibilization have only a marginal effect on the dynamic mechanical behavior of the ternary blends. Yet, compatibilization shifted the polymers' TgS to higher temperatures. Both glass fillers increased the elastic modulus of the binary blends, where GF performed better than GB as a reinforcing agent. GF slightly increased the strength of the binary blends while, GB reduced it. Both fillers reduced the ductility of the binary blends. The blends' mechanical properties were related to the morphology and their components' crystallinity. The compatibilizer increases both stiffness and strength and reduces deformability. [source] In-line near infrared monitoring of esterification of a molten ethylene,vinyl alcohol copolymer in a twin screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 11 2006Claire Barrès Near infrared spectroscopy has developed in the polymer industry as a tool for in-line monitoring of processes, particularly extrusion. However, little work is dedicated to the monitoring of chemical reactions involving polymer melts. In this paper, we examine the suitability of NIR spectroscopy for monitoring the chemical modification (catalyzed esterification) of a molten ethylene,vinyl alcohol copolymer by octanoic acid in a twin screw extruder. Extrusion samples are characterized off-line, for calibration purposes, for the three species of interest (i.e. unreacted acid, OH groups, and ester functions formed on the polymer backbone) by means of two techniques: 1H NMR, allowing all three species to be quantified, and residual (free) acid titration. However, the mass balance of free acid is not straightforward, due to loss of mass by volatilization at the vent. Therefore, 1H NMR analysis and acid titration have to be combined to allow for determination of all concentrations. Multivariate calibration is implemented here to quantify and subsequently predict the analyte concentrations by using the NIR spectroscopic data. Our calibration, based on a partial least squares regression software, provides satisfactory results in terms of correlation between actual and predicted concentrations. This work demonstrates the potential of in-line NIR spectroscopy for monitoring chemical reactions with polymer melts in extrusion. POLYM. ENG. SCI. 46:1613,1624, 2006. © 2006 Society of Plastics Engineers [source] On the linear correlation between microhardness and mechanical properties in polar polymers and blendsPOLYMER INTERNATIONAL, Issue 8 2003E Giménez Abstract The tensile elastic modulus (E), yield stress (,Y) and microhardness (MH) of neat and binary and ternary blends of glassy semicrystalline ethylene,vinyl alcohol copolymer (EVOH), a glassy amorphous polyamide and a semicrystalline nylon-containing ionomer covering a broad range of properties were examined. The tests were carried out on dry and water-equilibrated samples to produce stiffer and softer materials, respectively. From the results, more accurate linear correlations were found to describe adequately the microhardness, modulus and yield stress of these strongly self-associated polymers through hydrogen bonding. Copyright © 2003 Society of Chemical Industry [source] Degradation of high barrier ethylene,vinyl alcohol copolymer under mild thermal-oxidative conditions studied by thermal analysis and infrared spectroscopyPOLYMER INTERNATIONAL, Issue 6 2001José M Lagaron Abstract A study of the thermal-oxidative degradation of a high barrier ethylene,vinyl alcohol copolymer with 32,mol% of ethylene (EVOH) has been carried out by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) under mild temperature conditions above melting. It was found that time exposures of up to 11,h at temperatures between 9 and 33,°C above the EVOH melting point resulted in polymer weight losses of up to 3.6% with colour formation. The weight loss was faster at short times and slowed down with increasing exposure time. DSC showed a small decrease in crystallinity and melting point, melting-peak broadening and a slight increase in the glass transition temperature of the samples subjected to the more severe thermal-oxidative treatment. The FTIR experiments showed transformation of the vinyl alcohol hydroxyl groups into carbonyl groups and creation of double bonds. Changes in degradation kinetics and perhaps in mechanisms are thought to occur with increasing exposure time. Moreover, FTIR measurements suggest that transformation of the hydroxyl groups leads to a weakening of the overall hydrogen bonding strength in the degraded samples, and therefore a reduction in intermolecular cohesion can be anticipated. © 2001 Society of Chemical Industry [source] Implantation of ethylene vinyl alcohol copolymer for faecal incontinence managementANZ JOURNAL OF SURGERY, Issue 5 2010Jacqueline H. Stephens Abstract Purpose:, The primary objectives of this trial were to evaluate the safety and feasibility of treatment and to gain a preliminary indication of the effectiveness of ethylene vinyl alcohol injections into the anal sphincters of faecally incontinent patients. Methods:, Between April 2004 and February 2006, we conducted a prospective, single-arm, procedure optimization study of ethylene vinyl alcohol injections in 21 subjects with well-characterized faecal incontinence and an intact external anal sphincter at two Australian hospitals. Results:, There was a significant decrease in the Cleveland Clinic Florida Faecal Incontinence Score (CCFFIS) (P= 0.0005) and the Faecal Incontinence Severity Index score (P= 0.005) after treatment. At 12 months post-treatment, the mean CCFFIS had decreased by 37% (P= 0.0021), and 47% of subjects had a ,50% improvement in CCFFIS. There were significant improvements in embarrassment (P= 0.0455) and coping/behaviour (P= 0.0056) domains of the Faecal Incontinence Quality of Life. At 12 months, the mean anal canal length had increased by 29% (P= 0.066), with 40% of patients demonstrating increases of 50% or more. There were no further improvements following retreatment. Conclusions:, Ethylene vinyl alcohol injection into the anal intersphincteric plane is feasible and well tolerated. Improvement in faecal incontinence compared with baseline was seen. Retreating initial non-responders was not successful. [source] | |||||||||||||