Structure formation in stretched sheets of poly(butylene terephthalate)

Crystalline and amorphous sheets of poly(butylene terephthalate) (PBT) were drawn in the temperature range of 20–150°C. The molecular orientation and the relative amount of α- and β-form crystals in the stretched sheets were studied by wide-angle X-ray diffraction (WAXD) and density measurements. When crystalline PBT sheets are drawn at lower temperatures, α-form crystals are partially transformed into β-form crystals. Both α- and β-form crystals are formed by drawing amorphous PBT sheets. The relative amount of α- and β-form crystals is much more sensitive to drawing temperature than to draw ratio. The α-form crystallinity is higher at higher drawing temperature and increases slightly with increasing draw ratio. The second moments of orientation functions of α- and β-form crystals increase with increasing draw ratio, and the increase of the orientation function is suppressed at higher draw ratio. The orientation function of α-form crystals is higher than that of β-form crystals in a same sample.     

Short-Term Urban Water Demand Prediction Considering Weather Factors

Accurate and reliable forecasting plays a key role in the planning and designing of municipal water supply infrastructures. Recent studies related to water demand prediction have shown that water demand is driven by weather variables, but the results do not clearly show to what extent. The principal aim of this research was to better understand the effects of weather variables on water demand. Additionally, it aimed to offer an appropriate and reliable technique to predict municipal water demand by using the Gravitational Search Algorithm (GSA) and Backtracking Search Algorithm (BSA) with Artificial Neural Network (ANN). Moreover, eight weather factors were adopted to evaluate their impact on the water demand. The principal findings of this research are that the hybrid GSA-ANN (Agent?=?40) model is superior in terms of fitness function (based on RMSE) for yearly and seasonal phases. In addition, it is evidently clear from the findings that the GSA-ANN model has the ability to simulate both seasonal and yearly patterns for daily data water consumption.     

Crystallite size and lattice strain of lithiated spinel material for rechargeable battery by X‐ray diffraction peak‐broadening analysis

High‐energy ball milling is performed on Li_1.1Mn_1.95Fe_0.05O₄ spinel material, synthesized by sol‐gel method for lithium rechargeable battery, at different durations to obtain nanopowders of finite size distributions. The powders are investigated by means of scanning electron microscopy, particle size distribution, and X‐ray diffraction (XRD) measurements. The structural analysis of the powders is performed to investigate the effect of milling on the particle size, crystallite size, and lattice strain. The scanning electron micrographs and size distribution measurements show that the particle size decreases with the increase in milling duration. The XRD results show that the widths of the diffraction peaks increase with the decrease of particle size (increase of milling duration). This broadening is analyzed according to Scherrer, Williamson‐Hall, and Halder‐Wagner methods. Peak broadening is attributed to contributions of crystallite size and lattice strain. While reducing the particle and crystallite sizes is desirable to achieve higher specific capacity and energy density of the battery active material, lattice strain leads to material degradation and a reduced capacity retention. Thus, when performing mechanical milling, lattice strain should be taken seriously into consideration to optimize the milling parameters and to enhance the materials electrochemical performance.     

A Method for Predicting Long-Term Municipal Water Demands Under Climate Change

Water Resources Management - The accurate forecast of water demand is challenging for water utilities, specifically when considering the implications of climate change. As such, this is the first...     

Graft polymerization of hydrophilic monomers onto textile fibers treated by glow discharge plasma

Graft polymerization of vinyl monomers was made onto some natural and synthetic textile fibers that were pretreated by glow discharge plasmas. Among the monomers investigated, 2-hydroxyethyl methacrylate (HEMA) produced the most improved grafting effects. Effects of plasma gas source, exposing time of glow discharge, grafting time, temperature, etc., on grafting were investigated. Postpolymerization in vacuum allowing oxygen shutoff was desirable for improved grafting yield. Air exposure of the plasma pretreated textile fabrics lead to decrease of grafting yield prominently because of the deactivation of radicals by oxidation. Grafting amount was dependent also on the nature of the substrate textile fibers, and cotton was, in general, more reactive. Breaking strength of yarns increased after graft polymerization of HEMA, while the strength decreased by etching of yarns by plasma treatments using nonpolymerizable gas species. Increase of the strength in the grafted yarn is attributed to binding effect of the grafted polymers as revealed from studies of morphology by scanning electron microscopy. © 1996 John Wiley & Sons, Inc.