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Lower Tensile Strength (lower + tensile_strength)
Selected AbstractsAntimicrobial activity of nisin incorporated in pectin and polylactic acid composite films against Listeria monocytogenesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2009Tony Jin Summary An extruded composite food packaging film containing pectin, polylactic acids (PLAs) and nisin was developed to inhibit Listeria monocytogenes. The mechanical properties and surface structure of the film were also examined. Cells of L. monocytogenes were reduced by 2.1, 4.5 and 3.7 log units mL,1 by the pectin plus PLA (pectin/PLA) film containing nisin (1000 IU mL,1 of tested liquid) in Brain Heart Infusion (BHI) broth, liquid egg white and orange juice, respectively, after 48 h at 24 °C. Pectin played an important roll in embedding nisin into the film. The pectin/PLA film had a similar stiffness but lower tensile strength, elongation and fracture energy than the pure PLA film. These data suggested that nisin incorporated into the pectin/PLA film was an effective approach to reducing L. monocytogenes in a typical growth medium (e.g. BHI broth) as well as in foods (e.g. orange juice and liquid egg). [source] Synthesis of novel moisture-curable polyurethanes end-capped with trialkoxysilane and their application to one-component adhesivesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2007Yukihiro Nomura Abstract Novel silane endcappers and novel polyurethanes end-capped with trimethoxysilane (silylated polyurethanes) were developed as water-curable materials in which the curing reaction occurred under humid conditions in the presence of dioctyltin diversatate as a curing catalyst. A variety of amine-terminated trimethoxysilane compounds were synthesized by the Michael addition reaction of commercially available 3-aminopropyltrimethoxysilane with acrylates, and the resulting silane endcappers were used to react with isocyanate-terminated polyurethanes, providing the silylated polyurethanes. The moisture-curable silylated polyurethanes were used for the preparation of novel one-component and solvent-free adhesives. The evaluated properties were the curing speed, the tensile shear bond strength, and the adherence to some substrates. The longer alkyl chains of the silane endcappers derived from various acrylates led to a slower curing speed, lower tensile strength at break, and longer elongation at break of the silylated polyurethanes. The tensile shear bond strength of the silylated polyurethane-based adhesive decreased with decreasing the trimethoxysilane end-capping ratio, whereas an increase in the adherence was observed. The adherence to the acrylic substrate was improved by changes in the main-chain structure of the polyurethane based on the composition of poly(propylene oxide) and poly(ethylene oxide). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2689,2704, 2007 [source] Acrylonitrile-butadiene-styrene nanocomposites filled with nanosized aluminaPOLYMER COMPOSITES, Issue 5 2008Kamal K. Kar A polymer nanocomposite was produced by acrylonitrile-butadiene-styrene (ABS) and ,-alumina was prepared through sol-gel process using aluminum nitrate and citric acid. The particle size was analyzed by X-ray diffraction and scanning electron microscopy (SEM) studies. The nanocomposites were characterized through tensile strength, Young's modulus, strain% at break, flexural strength, flexural modulus, and impact strength. The ABS/Al2O3 nanocomposites are found to have slightly higher Young's modulus, but lower tensile strength, strain% at break, flexural and impact strength than the virgin ABS. But its flexural modulus increases with increasing Al2O3 content in ABS matrix. The d-spacing was calculated in nanocomposites to evaluate the interaction between Al2O3 and ABS. The particle distributions in nanocomposites were studied by SEM. The fractured surfaces of tensile test samples were also examined through SEM and show that the ductile fracture of ABS is converted to brittle fracture with addition of Al2O3. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Thermomechanical behaviour of poly[acrylonitrile- co -(methyl acrylate)] fibres oxidatively treated at temperatures up to 180 °CPOLYMER INTERNATIONAL, Issue 11 2005Spyridon Soulis Abstract PAN fibres, consisting of poly[acrylonitrile- co -(methyl acrylate)], were oxidatively heat treated at low temperatures (up to 180 °C), during which the basic macromolecular backbone was not cyclized. The change of length of the fibres was determined under various treatment conditions (ie temperature, time, stress applied). Prolonged heat treatment resulted in lower tensile strength of the fibres. The pristine and treated fibres were characterized by Fourier-transform infrared (FTIR), NMR and UV-visible spectroscopy and by TGA, and the results were used for representing the different regions according to chemical aspects in a plot of temperature versus time; this is very important for the whole treatment process. A shrinkage model was proposed, having both scientific and technical importance. The change in activation volume of shrinkage of fibres with temperature, calculated from this model, is indicative of the physical transitions taking place at the molecular scale. Copyright © 2005 Society of Chemical Industry [source] | ||||||||||