Encapsulation of air‐filled poly(dimethylsiloxane) microballoons in polyimide as a polymeric low ε dielectric

Air‐filled microballoons of poly(dimethylsiloxane), ie PDMS, have been encapsulated in polyimide. The molecular assembly so formed has shown surface dominance by PDMS while analytical techniques, such as X‐ray photoelectron spectroscopy and infrared spectroscopy, have confirmed a similar distribution in the bulk. The electrical properties of the resultant polymer have been studied and the relative permittivity has been found to be very low while other beneficial attributes of the polyimide have been retained. Copyright © 2004 Society of Chemical Industry     

Nomadic Culture: Cultural Support for Working Anytime, Anywhere

This article argues that a nomadic culture is required to achieve the competitive benefits of a workforce using ubiquitous computing technologies. A nomadic culture is defined as a collection of artifacts, beliefs, and basic assumptions based on a prior published model of organizational culture in general, the term nomadic culture is defined in this article. the authors provide lists of questions for managers to conduct an internal cultural audit.     

Degradation mechanism and kinetic model for photocatalytic oxidation of PVC-ZnO composite film in presence of a sensitizing dye and UV radiation

White or plastic pollution has become a serious concern to the environmentalists for the last few years. Degradation of waste plastics in conventional incinerators leads to emission of carcinogenic dioxins to the atmosphere. In this work, an attempt has been made for the photocatalytic degradation of polyvinyl chloride (PVC) using ZnO as semi-conductor catalyst in the form of PVC-ZnO composite film. The surface morphology as well as the FTIR spectroscopy of the irradiated film has been critically examined. The degradation was measured by weight loss data and was found to follow a pseudo-first order rate equation. The various parameters studied were loading of the semi-conductor, intensity of UV radiation and presence of Eosin Y as a sensitizing dye. It was observed that dye-sensitization enhanced degradation of PVC to a large extent. A possible mechanism has been suggested and the corresponding rate equation has been modeled for the dye-sensitized rate of degradation. The model has been validated by the experimental data.     

基于MATLAB对Wi-MAX与其他技术的比较和可适性分析(英文)

目前全球电信系统的宽带技术已经影响巨大.如果没有宽带接入技术,就不可能有效和迅速进入信息超级高速公路.而目前的蜂窝技术或现有的宽带网络,只能满足部分要求.因为,这些技术的速度较低而成本较高.因此,人们需要更快捷和成本更低的宽带接入技术.WiMAX(微波接入全球互联)技术能够满足目前的需求.最近,WiMAX系统已引入全球宽带接入技术领域.本文研究表明:与其他现存技术相比,WiMAX系统提供的技术不属于通常的Wi-Fi、2.5cellular系统和其他现有技术,该技术可以对现有网络娱乐服务技术进行有效的补充,同时,WiMAX技术还能够提供更高的速度,且成本更低.由于WiMAX技术的发展和在世界上被普遍采用,它将给宽带服务领域带来革命性的变化,将成为现代娱乐生活的组成部分.     

Analytical interpretations of static and dynamic mechanical properties of thermoplastic elastomer toughened PLA blends

Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer (TPE) styrene–ethylene–butylene–styrene‐g‐maleic anhydride (SEBS‐g‐MA) copolymer using a micro compounder which used melt recirculation approach for efficient dispersion of SEBS‐g‐MA in PLA. The SEBS‐g‐MA volume fraction (Φ_d) was varied between 0.07 and 0.48. Dynamic mechanical analysis showed 10.4 °C decrease in glass transition temperature at Φ_d = 0.48. Differential scanning calorimetry results exhibited shift in cold crystallization temperature to a higher temperature in the presence of SEBS‐g‐MA. Thermogravimetric analysis presented enhanced thermal stability of PLA/SEBS‐g‐MA blends. Tensile strength and modulus decreased while elongation‐at‐break and Izod impact strength increased in the blends. Theoretical models were employed to analyze the tensile properties of the blends in order to evaluate the blend structure. The microstructural attributes were characterized by wide‐angle X‐ray diffraction, Fourier‐transform infrared spectroscopy, and scanning electron microscopy of cryofractured, impact fractured, and tensile fractured surfaces. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45644.     

Absorption of carbon dioxide in piperazine activated concentrated aqueous 2-amino-2-methyl-1-propanol solvent

In this work new experimental data on the rate of absorption of CO₂ into piperazine (PZ) activated concentrated aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) over the temperature range 303–323 K are presented. The absorption experiments have been carried out in a wetted wall contactor over CO₂ partial pressure range of 5–15 kPa. PZ is used as a rate activator with a concentration ranging from 2 to 8 wt% keeping the total amine concentration in the solution at 40 wt%. The physical properties such as density and viscosity of concentrated aqueous AMP+PZ, as well as physical solubility of CO₂ in concentrated aqueous AMP+PZ, are also measured. New experimental data on vapor liquid equilibrium (VLE) of CO₂ in these concentrated aqueous solutions of AMP+PZ in the temperature range of 303–323 K have also been presented. The VLE measurements are carried out in an equilibrium cell in CO₂ pressure range of 0.1–140 kPa. A thermodynamic model based on electrolyte non-random two-liquid (eNRTL) theory is used to represent the VLE of CO₂ in aqueous AMP+PZ. Liquid phase speciations are estimated considering the nonideality of concentrated solutions of the amines and the calculated activity coefficients by eNRTL model. The CO₂ absorption in the aqueous amine solutions is described by a combined mass transfer-reaction kinetics model developed according to Higbie's penetration theory. The model predictions have been found to be in good agreement with the experimental results of the rates of absorptions of CO₂ into aqueous AMP+PZ.     

Thermo mechanical properties of organically modified halloysite nanotubes/cyclic olefin copolymer composite

This report deals with the development of unmodified and modified halloysite nanotube (HNT) based cyclic olefin copolymer (COC) composites. Maleic anhydride grafted polyethylene (MA‐g‐PE) has been used as a compatibilizer. Exfoliation of organically modified HNTs (mHNTs) and dispersion of it in polymer matrix was observed by X‐ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy analysis, respectively. Augmented dynamic mechanical and thermal properties of the composites were provided by incorporating mHNTs into the pure matrix. In this work, we have proposed that the modification of HNTs enhanced the dispersion and strong interfacial interaction which led to better performance of the composites where MA‐g‐PE acts as a bridging tool between polar clays and nonpolar COC. POLYM. COMPOS., 36:955–960, 2015. © 2014 Society of Plastics Engineers