The Influence of Blend Ratio on the Morphology,Mechanical, Thermal,and Rheological Properties of PP/LDPE Blends

This paper reports on how the blend ratio and morphology influence the mechanical, thermal, thermomechanical, and rheological properties of poly(propylene) (PP)/low density polyethylene (LDPE) blends. The blend morphology is composed of the major matrix phase and the minor phase, with subinclusions of the major matrix existing within the minor phase. Blends containing low amounts (<20 wt%) of either phase exhibit partial miscibility but the phases are immiscible at higher contents. Partial miscibility of the blends is revealed by scanning electron microscopy studies showing fibril‐like structures and confirmed by rheology. The tensile modulus of the blends decreases with increasing amounts of LDPE, but low LDPE contents exhibit positive deviation from the mixing rule of mixture due to partial compatibility. The crystallinity of PP is affected less than that of LDPE in the blends. Thermomechanical and rheological properties of neat polymers are significantly influenced by blending. The blend ratio and morphology influence impact strength and elongation at break, and the result demonstrates that the 80/20 PP/LDPE blend offers a balance among the mechanical and material properties that are essential for flexible packaging applications.

     

Hedgehog Antagonist Pyrimidine–Indole Hybrid Molecule Inhibits Ciliogenesis through Microtubule Destabilisation

One of the crucial regulators of embryonic patterning and tissue development is the Hedgehog‐glioma (Hh‐Gli) signalling pathway; its uncontrolled activation has been implicated in different types of cancer in adult tissues. Primary cilium is one of the important factors required for the activation of Hh signalling, as it brings the critical components together for key protein–protein interactions required for Hh pathway regulation. Most of the synthetic and natural small molecule modulators of the pathway primarily antagonise Smoothened (Smo) or other effectors like Hh ligand or Gli. Here, we report a previously described Hh antagonist, with a pyrimidine–indole hybrid (PIH) core structure, as an inhibitor of ciliogenesis. The compound is unique in its mode of action, as it shows perturbation of microtubule dynamics in both cell‐based assays and in vivo systems (zebrafish embryos). Further studies revealed that the probable targets are α‐tubulin and its acetylated form, found in the cytoplasm and primary cilia. PIH also showed axonal defasiculation in developing zebrafish embryos. We thus propose that PIH antagonises Hh signalling by repressing cilia biogenesis and disassembling α‐tubulin from its stabilised form.     

Investigation of wax deposit ‘sloughing’ from paraffinic mixtures in pipe flow

Deposit ‘sloughing’ from ‘waxy’ crude oils has been described in the literature as a possible mechanism, leading to partial or complete dislodging of the deposit from the pipe wall due to changes in flow parameters. A bench‐scale flow loop apparatus was used to investigate ‘sloughing’ with prepared single‐phase ‘waxy’ mixtures of a multicomponent paraffinic wax dissolved in a multicomponent solvent. Experiments were performed to study the changes in the deposit‐layer thickness due to step increments in the ‘waxy’ mixture flow rate, the mixture temperature, and the coolant temperature. It was observed that the deposit‐layer thickness decreased with an increase in each of the three parameters; however, a complete or sudden dislodging of the deposit‐layer did not occur in any of the experiments. A steady‐state heat‐transfer model was used to predict the variation in the deposit mass or thickness due to changes in the selected parameters. In each case, the step‐wise decrease in the deposit thickness, as observed experimentally, was predicted to be caused by changes in the thermal resistance and/or thermal driving force.     

Lightweight,Elastomeric, and Flame‐Retardant Foams from Expanded Chlorinated Polymers

Intrinsically flame‐retardant polymers based on lightweight and elastomeric microcellular foams are successfully prepared from flexible chlorinated polyethylene (CPE)/chlorinated polyvinylchloride (CPVC) compounds through compression molding foaming technology. The incorporation of CPVC to CPE at once improves the foam characteristics, and enhances the mechanical and fire performances. Due to the plausible intermolecular and intramolecular crosslinking among the polymer chains, the dense network structure of CPE/CPVC with enhanced strength results in increased cell size, reduced cell density, and improved dimensional stability of CPE/CPVC foams (CCFs). These improvements are noticed to be enhanced with increasing CPVC content in the CCF. Also, the flame‐retardant properties of the foams (i.e., limiting oxygen index and cone calorimeter combustion) are found to be increased with the increase of CPVC content. For instance, a highly flame‐retardant CCF at CPE/CPVC ratio of 60/40 shows a shorter combustion period, as derived from the respective heat release rate vs time curve. Corresponding peaks of heat release rate, total heat release rate, peak of mass loss rate, total smoke release, and char residue are recorded to be 8.4%, 5.8%, 3.0%, 6.6%, and 1000.1% of those recorded for the pristine CPE foam.     

Effect of nano-Al2O3 particles on the corrosion behavior of alkyd based waterborne coatings

A modification in the alkyd based waterborne coatings was studied with the addition of 0.05%, 0.1%, 0.2%, and 0.3% nano-Al₂O₃. Corrosion performance of the nano-composite coatings were evaluated by applying these nanocomposites on mild steel substrate and exposing them to salt spray, humidity, and accelerated weathering. Mechanical properties were studied by subjecting the coating to scratch and abrasion test. The results showed that, with an increase in the concentration of nano-Al₂O₃ there was an improvement in the corrosion resistance, UV resistance, and mechanical properties of the coatings indicating the positive effect of addition of nano-Al₂O₃ particles in the coatings. Further, the transparency of the coating was not altered, maintaining the optical clarity of the coating.     

Recent Progress on Nafion‐Based Nanocomposite Membranes for Fuel Cell Applications

Proton exchange membrane fuel cells (PEMFCs) have attracted tremendous attention because of their high efficiency compared to other types of fuel cells. Nafion is the most commonly used polymer for membranes used in PEMFCs. A large variety of nanoparticles of different natures and sizes can be blended with a Nafion matrix, generating a new class of nanostructured electrolyte membrane with interesting physical properties. In this paper, we discuss the recent progress in the field of Nafion‐based nanocomposite membranes. They exhibit a significant improvement in thermo‐mechanical and thermal stability as well as proton conductivity at very low filler contents. The preparation, characterization, and properties of various types of Nafion‐based nanocomposite membranes are critically reviewed, and detailed examples are summarized.

     

High‐Performance Carbon Nanotube‐Reinforced Bioplastic

The inherent properties of poly(lactide), a biocompatible and biodegradable polymer, are concurrently improved by the incorporation of a small amount of surface functionalized carbon nanotubes. A new method has been used to functionalize the CNTs' outer surface with hexadecylamine. A composite of PLA with functionalized CNTs has been prepared by melt‐extrusion. FT‐IR spectroscopy, Raman spectroscopy, DSC, and optical microscopy are used to investigate the thermal and mechanical property improvement mechanism in f‐CNTs containing PLA composite.

     

Electrochemical characterization of a new binary oxide of Mo with Co for O2 evolution in alkaline solution

The α-CoMoO₄ oxide has been obtained by a precipitation method and investigated for the first time for electrocatalysis of the oxygen evolution reaction (oer) in alkaline medium. This method produced the pure crystalline CoMoO4 monoclinic phase with crystallite size ∼46 nm and lattice constants: a = 9.666 Å, b = 8.854 Å, c = 7.755 Å and β = 113.82°. The average particle size (based on area density) and the BET surface area of powders of the oxide were 11.58 μm and 9.4 m² g⁻¹, respectively. Results show that the new oxide is quite active for the oer. Values of the Tafel slope and the reaction order with respect to OH⁻ concentration are observed to be ∼60 mV and ∼1, respectively.     

Anisotropic Dielectric and Electrical Properties of Hot-Forged SrBi4Ti4O15 Ceramics

The effect of grain orientation on the dielectric and electrical properties of SrBi₄Ti₄O₁₅ ceramics are studied by impedance and modulus spectroscopy. The degree of orientation calculated from the X-ray diffraction pattern is found to be 94.2% along the c-axis of the crystal structure. The ratio of permittivity along the perpendicular to parallel direction is found to be ∼2.5 at the Curie temperature. The nonsuperimposition of the normalized Z″ and M″ versus frequency plot revealed that the conduction is localized and deviate from ideal Debye-like behavior. The conduction mechanism has been explained on the basis of jump relaxation model.