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This study aims to predict the compression behavior of ultra-high molecular weight polyethylene (UHMWPE) at various temperatures (25, 40, and 55[degrees]C) and strain rates (~[10.sup.-4]/s and ~[10.sup.-2]/s) using a single set of three-network (TN) viscoplastic model parameters. The TN model is made up of three parallel networks: networks A and B use nonlinear springs and dashpots to control the responses of the crystalline phase and confined amorphous phases, respectively, while network C captures the macromolecular amorphous networks using a single nonlinear spring. A single set of TN model parameters captures the yield and post-yield hardening responses of the stress-strain curves at experimental temperatures and strain rates. When these TN model calibrated parameters are used as material property in a commercial finite element tool to simulate UHMWPE compression, the predicted and simulated results match well, showing the model's fidelity. Additionally, the model predicts experiments conducted at 40 and 70[degrees]C with loading rates of ~[10.sup.-3]/s and ~[10.sup.-2]/s, respectively. The study also correlates the deformations of UHMWPE's crystalline structure and macromolecular amorphous networks with its global stress versus strain response by extracting stresses from individual networks of the TN model at different strain rates and temperatures. Highlights * UHMWPE's mechanical behavior predicted by a single set of TN model parameters * TN model predicts mechanical response at various strain rates and temperatures. * TN model explains microstructural crystalline and amorphous phase deformations. KEYWORDS compression properties, numerical simulations, three-network (TN) viscoplastic model, UHMWPE, 1 | INTRODUCTION Ultra-high molecular weight polyethylene (UHMWPE) is one such polymer, which demonstrates an encouraging potential as an impact, chemical, and wear-resistant material. (1) UHMWPE has found diverse applications, [...]

A poly(methyl methacrylate)/Ti[O.sub.2] (PMMA/Ti[O.sub.2]) hybrid was synthesized in the presence of triethylene glycol dimethacrylate as a crosslinking agent. Different types of Ti[O.sub.2] rutile, anatase, and P25 were employed in this study, and the morphology, crystalline structure, particle size, thermal properties, photocatalytic activity, and antibacterial activity were investigated. The results show that the particle size of the PMMA/Ti[O.sub.2] hybrids was in the range of 73.3 nm to 210.0 nm. The morphology of the PMMA/Ti[O.sub.2] hybrid was spherical with a narrow particle size distribution. The thermal properties of the PMMA/ Ti[O.sub.2] hybrid were analyzed using differential scanning calorimetry. The glass transition temperature of the PMMA/Ti[O.sub.2] was higher than that of pristine PMMA. The photocatalytic properties were investigated by monitoring the color changes of methylene blue (MB). It was found that the MB degradation for the PMMA hybrid anatase Ti[O.sub.2] (PMMA/aTi[O.sub.2]) reached 80%, which was similar to that for the PMMA hybrid P25Ti[O.sub.2] at 83% in 60 min. The minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of the PMMA/Ti[O.sub.2] hybrids were estimated. The MIC of PMMA hybrid anatase Ti[O.sub.2] was 9.65 mg [mL.sup.-1] (P. aeruginosa) and 19.33 mg [mL.sup.-1] (S. aureus) which can inhibit the bacteria. The MBC results of the PMMA/aTi[O.sub.2] were 19.33 mg [mL.sup.-1] for both P. aeruginosa and S. aureus. Highlights * Ti[O.sub.2] nanoparticle encapsulation with poly(methyl methacrylate) via miniemulsion polymerization. * Encapsulated particles exhibit excellent photocatalytic properties. * Triethylene glycol dimethacrylate (TEGDMA) crosslinking ensures stability, enhances photocatalytic property. * The influence of TEGDMA on the hybrid was discussed. KEYWORDS antibacterial, hybrid, miniemulsion, photocatalytic, PMMA, titanium dioxide, 1 | INTRODUCTION Due to the intensive development and popularization of hybrid polymer materials in the past decades, novel hybrid polymers have found applications in diverse fields such as polymer [...]

The formation of spherulites in polymers is a well-known phenomenon; when the polymer is crystallized by cooling from the melt, crystal lamellae grow out from a nucleation site in a spherical pattern. If the material is annealed on a planar surface, and viewed between crossed polarizers in a microscope, a Maltese cross with a banding pattern is observed. Where the crystals grow in a direction not parallel to the polarizers, the sample lights up. Often banding of the lit regions is observed, and is believed to be due to rotations of the crystal lamellae around the growth direction. Because it is well known that polarized Raman spectra respond to crystal orientation, we thought it would be interesting to try to document the relationship between the banding behavior and Raman polarization/orientation behavior. In this column I will show results of such an investigation of spherulites of poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHx) with varying composition., Those of you who follow my column know that PHBHx has been my 'favorite' polymer over the last few years, as PET (polyethylene terephthalate) was for many years previously. PHBHx [...]

Abstract The Kevlar fibers were irradiated at up to 2500 kGy using a 10 MeV electron accelerator. The effects of radiation on the Kevlar fibers were evaluated in detail. The [...]

The synthesis of a series of 2- and 8-substituted 4-amino-7-chloroquinolines is presented. Starting from 4,7-dichloroquinolines, the chloro in the 4-position can be effectively substituted using amino alcohols to yield novel analogues of the antimalarial (hydroxy)chloroquine. Both short-chain (2-aminoethanol) and long-chain (5-[N-ethyl-N-(2-hydroxyethyl)amino]-2-aminopentane) coupling partners can be used. While ketone and nitro functionalities were found to be incompatible with the coupling conditions, electron-donating amino and dimethylamino substituents were tolerated. In addition to characterization in solution using multinuclear NMR spectroscopy and high-resolution mass spectrometry, single-crystal X-ray structures are presented of two 4,7-dichloroquinolines as well as three of the N-alkylated products including a unique species in which a pyrrole heterocycle formed at the 2-position of the quinoline subunit and a rare example of a 4-aza-1,10-phenanthroline. Key words: chloroquine analogues, quinoline synthesis, X-ray crystallography, Introduction Quinoline (benzo[b]pyridine) is a prominent pharmacophore, appearing in numerous biologically active synthetic molecules and natural products including prominent antimalarials such as the cinchona alkaloid quinine and the clinically critical [...]

The synthesis and characterisation (IR, NMR, HR-MS, and X-ray crystallography) of six oxazoline Zn complexes, containing enolate ligands derived from a series of (Z)-1-R-2-(4',4'-dimethyl-2'-oxazolin-2'-yl)-efh-1-en-1-ols (R=[C.sub.6][H.sub.5], [C.sub.6][H.sub.4]-p-N[O.sub.2], [C.sub.6][H.sub.4]-p-O[CH.sub.3], [CF.sub.3], [CH.sub.3], or [CMe.sub.3]) is detailed. All derivatives are air-stable solids of formula Zn[([L.sup.n]).sub.2] and are formed in the presence of the title ligands and [NEt.sub.3]. Reasonable yields (53%-82%) are obtained with the exception of R= [CMe.sub.3] (9%); in this case, by-product formation and high solubility affected complex isolation. Crystallographic characterisation reveals that in all cases the ligands are bound in a [kappa].sup.2]-N, O-bonding motif. Little structural diversity is noted within the series; these complexes are further placed into structural context with related Zn materials containing oxazoline, phenolate, and (or) Schiff base ligands. Key words: oxazoline, coordination complexes, zinc, enolate, X-ray crystal structure, Introduction The naturally occurring Group 12 elements hold a unique position within coordination chemistry due to the overwhelming predominance of the +2 oxidation state. This is, of course, a result [...]

A series of [Tb.sup.3+] doped cubic Mg[Al.sub.2][O.sub.4] green phosphors were synthesized via hydrothermal method followed by a post-annealing process. The variation regularity of phase structure, morphology, particle size and concentration quenching mechanism were investigated. The results showed that the crystal structure of matrix materials was not affected when [Tb.sup.3+] ions were introduced. In addition, the micrometer-sized rods and excellent dispersion of the particles were obtained by adding urea. Under excitation at 377 nm, the phosphors exhibited the characteristic of [Tb.sup.3+] emissions with the peaks located at 488 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.6]), 544 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.5]) and 588 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.4]), respectively. Moreover, based on optical analysis, it can be inferred that electric dipole-dipole (d-d) interaction plays an important role in concentration quenching process of [Tb.sup.3+] ions. The green light emitting phosphor Mg[Al.sub.2][O.sub.4]: [Tb.sup.3+] can be realized by adjusting the concentrations of [Tb.sup.3+], and the optimum concentration of [Tb.sup.3+] ions in Mg[Al.sub.2][O.sub.4] was found to be 0.02. Finally, the average fluorescence decay lifetime and the CIE chromaticity coordinates of [Mg.sub.0.98][Al.sub.2][O.sub.4]:0.02[Tb.sup.3+] phosphor were calculated to be 1.2005 ms and (0.3197 0.4109), respectively. The above results suggest that the developed phosphor could have potential to be used as a single-phase green emission phosphor for near-ultraviolet light-emitting diode (NUV-LED) applications., Aluminate-based luminescent materials activated by rare earth ions are of interest due to their good water resistance, stable chemical properties, high efficiency, and lower cost (1-3). As the use of [...]

SELF-ASSEMBLING CRYSTAL STRUCTURES Scientists at Cornell University, Ithaca, N.Y., used a targeted computational approach to find more than 20 new self-assembled crystal structures. The team conducted a targeted search for [...]