Studies on transport of vapor and solute molecules through polyvinyl alcohol‐based clay containing nanocomposites

The present study focuses on fabricating of polymer–clay nanocomposites by in situ polymerization method and investigating their permeability behavior toward vapor and liquid molecules, thus, to evaluating barrier properties of the nanocomposites. For this purpose, acrylonitrile (AN) monomer was grafted on to poly(vinyl alcohol) (PVA) chains after the addition of very low amount of fuller's earth (clay) into polymer matrix using a suitable initiator, such as potassium persulphate (KPS), and crosslinker N‐N′ methylene bisacrylamide (MBA). The prepared nanomaterials were characterized by Fourier‐Transformation infrared (FTIR) spectroscopy and wide‐angle X‐ray diffraction (WXRD) techniques. The morphological features of designed materials were studied by scanning electron microscopy. The graft materials impregnated with fuller's earth were examined for their permeability behavior by observing the permeation of solute and vapor molecules from aqueous dye solution and volatile organic solvent, respectively. The composition of the nanocomposites and the amount of fuller's earth content were found to affect the passage of solute and vapor molecules across the nanocomposite membrane. The permeation capacity was quantified by evaluating permeability parameters. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Environmental Open Data in Urban Platforms: An Approach to the Big Data Life Cycle

ABSTRACT

Through a literature review, this paper proposes an assessment framework to evaluate environmental open data in urban platforms under the data life cycle approach. For this purpose, a set of quantitative and qualitative indicators has been defined for each of the stages of the data life cycle: acquisition, access, analysis, and application. As confirmation of the capabilities of this approach, we illustrate the results of its application in six data portals along with analyses, comparisons, and conclusions regarding the results. The cases reveal that an interest exists in providing environmental information, but the capability to transform the data information into knowledge relevant for cities is rather low.     

Application of long-term simulation programs for analysis of systemislanding

This paper describes the main results and conclusions from the application of two different long-term stability programs to the analysis of a system islanding scenario for a study case developed by Red Electrica de Espana (REE), based on the Spanish system. Two main goals were to evaluate the performance of both simulation programs in the long-term stability area, and to analyze the influence of some important control and protection elements (tie-line loss-of-synchronism relays, underfrequency load-shedding, load-frequency control, and power plant dynamics). Conclusions about modeling and computational requirements for system islanding (frequency) scenarios and use of long-term stability programs are presented     

The moderating role of temporary work on the performance of lean manufacturing systems

Companies are extensively employing lean manufacturing practices and temporary work, which at face value are in stark contrast to each other. While lean manufacturing emphasises the value of workers, temporary work refers to precarious work arrangements that, based on social exchange theory, may harm workers’ commitment. The objective of this paper is to unveil the role of temporary work on the lean manufacturing – operational performance (i.e. cost, quality, delivery, flexibility) relationship. To answer our research question and test our hypotheses we utilise cross-country data collected through the sixth iteration of the International Manufacturing Strategy Survey and conduct multilevel regression analysis. Our results indicate that while lean manufacturing improves operational performance, the use of temporary work positively influences the relationship between lean manufacturing and mix and volume flexibility performance.     

Designing of fullers‐earth‐containing poly(vinyl alcohol)‐g‐poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) nanocomposites: Swelling and deswelling behaviors

In this study, polymer–clay nanocomposites (PCNs) composed of poly(vinyl alcohol)s (PVAs), poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid), and fullers earth were prepared by the effective dispersal of inorganic nanoclays in the organic PVA matrix via in situ free‐radical polymerization with potassium persulfate as an initiator and N,N‐methylene bisacrylamide as a crosslinker. The monomer, 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid, was grafted onto the PVA backbone, and at the same time, fullers earth layers were intercalated and exfoliated into the grafted copolymer, especially at a low or moderate loading of the fullers earth. The synthesized PCN materials were characterized by Fourier transform infrared spectroscopy and wide‐angle X‐ray diffraction techniques. The morphological features of the synthesized materials were studied by scanning electron microscopy; this revealed that the swelling ratio of this nanocomposite increased with increasing fullers earth content. The X‐ray diffraction results indicated that the fullers earth was exfoliated in the nanocomposite matrix, and its introduction into the polymer matrix enhanced the percentage crystallinity of the polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010