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     

The effect of ambient moisture and temperature conditions on the mechanical properties of glass fiber/carbon fiber/nylon 6 sandwich hybrid composites consisting of skin‐core morphologies

The concept of skin‐core (SC) morphology was used to make sandwich hybrid composites in which the skin and core were composed of different fibers in the same matrix. The sandwich blends comprising glass skin with carbon core and vice versa were compared with those of the hybrid composite, while the respective carbon (CF) and glass fiber (GF) composites served as points of reference. The composites were compounded and fabricated into injection molded tensile specimens and 3‐mm thick plaques. The effect of ambient temperature and moisture was studied. The fracture mechanical characterization of the various materials was done by using notched compact tension (CT) specimens. Tensile properties were also used to characterize the composites. Morphogical studies based on scanning electron microscopy and light microscopy were used to elucidate fracture characteristics. Deterioration of properties was noticed under hot and humid conditions. Synergism in flexural properties was observed in the CF/GF/PA hybrid composite. The mechanical properties of the CF/GF/PA hybrid are closer to those of CF/PA, suggesting a cost advantage by substituting half of the carbon fibers with glass fibers. Dynamic mechanical analysis results revealed that synergism in T_g is attained by blending or sandwiching glass and carbon fibers. Morphological studies reaffirmed the skin‐core morphology of the composites. POLYM. COMPOS., 26:52–59, 2005. © 2004 Society of Plastics Engineers.     

Microstructure and Mechanical Property Correlation of Mg-Si Alloys

Silicon - The present work aims at understanding the microstructure and mechanical property correlation of hypo (Mg-0.5, 0.7, 1.15 wt% Si) and hyper (Mg-2, 4, 6, 8 and 10 wt% Si) eutectic binary...     

PVA/Gd2O3@Zno Nanocomposite Films as New Uv-Blockers: Structure and Optical Revelations

Journal of Inorganic and Organometallic Polymers and Materials - Herein we have synthesised Gadolinium oxide doped Zinc oxide (Gd2O3@ZnO) by solution combustion method and incorporated it as a...     

Effect of cooling methods on residual compressive strength and cracking behavior of fly ash concretes exposed at elevated temperatures

This paper presents the effects of cooling methods on residual compressive strength and cracking behavior of concretes containing four different class F fly ash contents of 10%, 20%, 30% and 40% as partial replacement of cement at various elevated temperatures. The residual compressive strength of the aforementioned fly ash concretes is measured after being exposed to 200, 400, 600 and 800 °C temperatures and two different cooling methods, for example, slow cooling and rapid water cooling. Results show that the residual compressive strengths of all fly ash concretes decrease with increase in temperatures irrespective of cooling regimes, which is similar to that of ordinary concrete. Generally, control ordinary concrete and all fly ash concretes exhibited between 10% and 35% more reduction in residual compressive strength because of rapid cooling than slow cooling except few cases. Cracks are observed over concrete specimens after being exposed to temperatures ranging from 400 to 800 °C. Samples that are slowly cooled developed smaller cracks than those rapidly cooled. At 800 °C, all fly ash concretes that are exposed to rapid cooling showed the most severe cracking. X‐ray diffraction analysis shows reduction of Ca(OH)₂ peak and formation of new calcium silicate peak in concretes containing 20% and 40% fly ash when subjected to 800 °C in both cooling methods. Thermo gravimetric analysis and differential thermal analysis results show increase in thermal stability of concrete with increase in fly ash contents. The existing Eurocode also predicted the compressive strength of fly ash concretes with reasonable accuracy when subjected to the aforementioned elevated temperatures and cooling methods. Copyright © 2014 John Wiley & Sons, Ltd.     

Increasing productivity in sculpture surface machining via off-line piecewise variable feedrate scheduling based on the force system model

Sculpture surface machining is a critical process commonly used in various industries such as the automobile, aerospace, die/mold industries. Since there is a lack of scientific tools in practical process planning stages, feedrates for CNC machining are selected based on the trial errors and previous experiences. In the selections of the process parameters, production-planning engineers are conservative in order to avoid undesirable results such as chipping, cutter breakage or over-cut due to excessive cutter deflection. Currently, commonly used CAD/CAM programs use only the geometric and volumetric analysis, but not the physics of the processes, and rely on experience based cutting tool database and users’ inputs for selection of the process parameters such as feed and speed. Usually, the feeds and cutting speeds are set individual constant values all along the roughing, semi-finishing, and finishing processes. Being too conservative and setting feedrate constant all along the tool path in machining of sculpture surfaces can be quite costly for the manufacturers. However, a force model based on the physics of the cutting process will be greatly beneficial for varying the feedrate piecewise along the tool path.The model presented here is the first stage in order to integrate the physics of the ball-end milling process into the selection of the feeds during the sculpture surface machining. Therefore, in this paper, an enhanced mathematical model is presented for the prediction of cutting force system in ball end milling of sculpture surfaces. This physical force model is used for selecting varying and ‘appropriate’ feed values along the tool path in order to decrease the cycle time in sculpture surface machining. The model is tested under various machining conditions, and some of the results are also presented in the paper.     

Die Abtrennung von Ölsäuremonoglycerid aus einem Glyceridgemisch mit Hilfe eines überkritischen Extraktionsmittels

Separation of Glycerol-monooleate from a Mixture of Glycerides by Means of a Supercritical Extractant The continuous separation of pure monoglycerides out of a mixture of glycerides by means of supercritical fluid extraction was investigated. As supercritical extracting agent carbon dioxide containing propane as an entrainer was used. The phase equilibria concerning the process were measured and are discussed. In an extraction apparatus consisting of an extraction column and two separators the viability of the process was tested. At 40°C and 120 bar a product with 99.5 wt.% monoglycerides was manufactured out of a mixture of glycerides containing 59 wt.% monoglycerides.     

Characterization and gamma radiation effects on poly(methyl methacrylate) doped with some benzylidene polymers

Anionic solution polmerization studies of benzylidene malononitrile, benzylidene ethyl cyanoacetate and their para chloro derivtives in dimethyl formamide (DMF) as a reaction medium using pipridene as initiator under nitrogen atmosphere at 100 °C were carried out. Infrared, ¹H NMR and ultraviolet-visible (UV-Vis) spectroscopic studies for the obtained polymers were investigated. The effect of γ-irradiation on PMMA films doped with 1 % of the benzylidene polymers was investigated by uv-vis spectroscopy. A change in the intensity of absorption bands with increasing irradiation dose was recorded. It is suggested that PMMA films doped with this type of benzylidene polymer can be used as dosimeter.     

Enantioselective hydrogenation of ethyl pyruvate Long-term performance of chirally modified Pt/zeolite catalysts

The long-term performance of 5 wt.% Pt/zeolite catalysts (HNaY with different degrees of ion exchange) modified with (−)cinchonidine was studied. The enantioselective hydrogenation of ethyl pyruvate to R(+)ethyl lactate was used as the model reaction. The Pt/zeolites are effective catalysts for long-term use, if the chiral modifier is added before each cycle of hydrogenation. The optimal ratio between the amount of catalyst and chiral modifier essentially depends on both the specific Pt surface area of the catalyst and the solvent used. It is found that the use of acetic acid as solvent results in a higher long-term performance than cyclohexane. This is due to the competitive adsorption between the chiral auxiliary and acetic acid on the Pt surface. Furthermore, the acidity of the solvent results in a weakening of the (−)cinchonidine/Pt interaction, which prevents an overloading of the Pt surface area with (−)cinchonidine or its decay products. This effect was determined by means of differential thermal analysis and elemental analysis. When cyclohexane is used as the solvent, the long-term performance is significantly improved by raising the carrier acidity.