A New Biodegradable Flexible Composite Sheet from Poly(lactic acid)/Poly(ε‐caprolactone) Blends and Micro‐Talc

The influence of talc loading on phase morphology of PLA/PCL/talc composites and improvement in resulting properties are reported. Talc‐based composites of PLA/PCL blends were prepared by melt blending. SEM analysis demonstrates that PLA appears as discrete domain phase, while PCL acts as a bulk phase in the blend. Talc addition decreases PLA domain sizes and voids in the matrix. This results in significant improvement of oxygen and water vapor barrier properties of composite by 33 and 25%, respectively, at 3 wt.‐% talc loading. DSC shows that talc acted as nucleating agent for PCL phase in the composite and improves its crystallinity. Various theoretical models based on dispersion and filler geometry are used to predict the tensile modulus and oxygen permeability.

     

Prototype development and field-test results of an adaptive multiresolution PANOPTES imaging architecture

The design, development, and field-test results of a visible-band, folded, multiresolution, adaptive computational imaging system based on the Processing Arrays of Nyquist-limited Observations to Produce a Thin Electro-optic Sensor (PANOPTES) concept is presented. The architectural layout that enables this imager to be adaptive is described, and the control system that ensures reliable field-of-view steering for precision and accuracy in subpixel target registration is explained. A digital superresolution algorithm introduced to obtain high-resolution imagery from field tests conducted in both nighttime and daytime imaging conditions is discussed. The digital superresolution capability of this adaptive PANOPTES architecture is demonstrated via results in which resolution enhancement by a factor of 4 over the detector Nyquist limit is achieved.     

Synthesis and characterization of high molecular weight side chain liquid crystalline/photoactive polymers

Various liquid crystalline and photoactive azobenzene monomers were synthesized and attached to copoly(methyl methacrylate‐glycidyl methacrylate) [copoly (MMA‐GMA)] to get high molecular weight side chain liquid crystalline (LC)/photoactive copolymers. Further, spacers are generated in situ and reactive groups are obtained after the modification. All monomers and polymers were thoroughly characterized by FTIR, ¹H and ¹³C NMR, UV‐VIS spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. All side chain LC polymers showed higher thermal stability than that of copoly(MMA‐GMA). Three LC and one azo monomer exhibited characteristic nematic mesophase where as one LC monomer has shown nematic and sanded smectic‐A texture. The rate of trans‐cis isomerization of polymer was lower than that of the monomer and both monomers and polymers showed slow back isomerization. Present approach offers convenient way to synthesize high/desired molecular weight photoactive LC polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Terminal functionalized hydroxyl‐terminated polybutadiene: An energetic binder for propellant

We report the functionalization of hydroxyl terminated polybutadiene (HTPB) backbone by covalently attaching 1‐chloro‐2, 4‐dinitrobenzene (DNCB) at the terminal carbon atoms of the HTPB. The modification of the HTPB by the DNCB does not alter the unique physico–chemical properties and the microstructure of the parent HTPB. IR, ¹H‐NMR, ¹³C‐NMR, size exclusion chromatography (SEC) and absorption spectroscopy studies prove that the DNCB molecules are covalently attached to the terminal carbon atoms of the HTPB. The π electron delocalization owing to long polymer chain, strong electron withdrawing effect of the DNCB molecule are the major driving forces for the covalent attachment of the DNCB at the terminal carbon atom of the HTPB. We are the first to observe the existence of intermolecular hydrogen bonding between the terminal hydroxyl groups of the HTPB. IR study shows that the attached DNCB molecules at the terminal carbon atoms of the HTPB breaks the intermolecular hydrogen bonding between the HTPB chains and forms a hydrogen bonding between the NO₂ groups of the DNCB and the OH groups of the HTPB. Absorption spectral study of the modified HTPB indicates the better delocalization of π electron of butadiene due to the strong electron withdrawing effect of the DNCB molecules. Theoretical calculation also supports the existence of hydrogen bonding between the OH and NO₂ groups. Theoretical calculation shows that the detonation performance of both the DNCB and the HTPB‐DNCB are promising. HTPB‐DNCB is the new generation energetic binder which has potential to replace the use of HTPB as binder for propellant.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Functional Evaluation of Soy Fatty Acid Methyl Ester Ketals as Bioplasticizers

A facile synthesis of the soy fatty acid methyl ester ketal has been accomplished using acetone in the presence of catalytic anhydrous ferric chloride starting from commercially available soy biodiesel (soy fatty acid methyl ester) after evaluating various synthetic procedures. The soy ketal product was fully characterized by nuclear magnetic resonance, infra-red and chromatography. The physical and analytical properties of soy ketal as determined by thermogravimetric analysis, viscosity acid and saponification values are acceptable for plasticizer applications. Soy ketal was compounded with polyvinyl chloride for evaluation of plasticizer properties such as efficiency, gelation, viscosity, volatility, thickening/aging behavior and stability. The thickening and aging behaviors of the soy ketal bioplasticizer are better than those of petroleum-based plasticizers such as diisononyl phthalate and diisononyl-cyclohexane dicarboxylate, but they need improvement in the areas of thermal stability and water extractability.     

Experience report: evolution of a web‐integrated software development and verification environment

This paper summarizes our experiences over the last 4 years in creating a web‐integrated software development and verification environment. The environment has been used for both research experimentation and education. It has been used in undergraduate computer science courses to teach modular software development and analytical reasoning principles at multiple institutions. In the process, the environment has undergone many refinements to meet demands for improved functionality and to leverage rapidly changing underlying technology for the improvements. The environment is tailored to present formal specifications and alternative implementations of components, and enable correctness checking through a server‐side verifying compiler. This paper presents a detailed account of the development and evolution of the environment—its functionality, user interface, and underlying technology—that we hope will serve as a model for others, especially as the benefits of online learning systems are becoming increasingly obvious. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparative Data Processing Approaches for Thermal Wave Imaging Techniques for Non-Destructive Testing

Thermal non destructive testing is a whole-field, non-contact and non-destructive inspection method used to reveal the surface or subsurface anomalies in a test sample. This paper describes a novel modelling and simulation technique of a three dimensional pulse compression method for non-stationary thermal imaging. This method requires much lower peak power heat sources than the widely used conventional pulsed thermographic methods (PT and PPT) and requires less time than sinusoidal modulated Lock-in Thermography (LT). In addition, simulation results obtained with the proposed techniques are compared with the conventional phase-based thermal imaging techniques (PPT and LT).     

Preparation and characterization of magnetic nanoparticles embedded in hydrogels for protein purification and metal extraction

The present work involves the development of hydrogel magnetic nanocomposites for protein purification and heavy metal extraction applications. The magnetic nanoparticles (MNPs) were prepared in situ in poly(acrylamide)-gum acacia (PAM-GA) hydrogels. The formation of magnetic nanoparticles in the hydrogel networks was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Scanning electron (SEM) microscopy studies revealed the formation of MNPs throughout the hydrogel networks. The average size of MNPs formed in the hydrogel networks was 3–5 nm as determined by transmission electron microscopy (TEM). The thermal properties of the hydrogel magnetic nanocomposites were evaluated by dynamic scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The magnetic properties of the developed hydrogel magnetic nanocomposites were determined by a vibrating sample magnetometer (VSM). The swelling properties of the hydrogel and the hydrogel magnetic nanocomposites were studied in detail. The hydrogel magnetic nanocomposites are utilized for the removal of toxic metal ions such as Co(II), Ni(II), and Cu(II) and for protein purification. The results confirm that the hydrogel magnetic nanocomposites exhibit superior extraction properties to hydrogels.