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The morphology of an incompatible polymer blend composed of poly(l-lactide) (PLLA) and poly(butylene succinate) (PBS) was examined by scanning and transmission electron microscopy, X-ray scattering, and X-ray photoelectron spectroscopy before and after the incorporation of an organoclay containing reactive functional groups, namely twice functionalized organoclay (TFC). TFC was prepared by treating...
Plasticized poly(l-lactide) (PLA) montmorillonite layered silicate (MLS) nanocomposites were compounded and blown-film processed using a co-rotating twin screw extruder. PLA was mixed with 10wt% acetyltriethyl citrate ester plasticizer and 5wt% of an organically modified montmorillonite at various screw speeds. Wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) determined...
Three new aromatic polyimides containing one or two replaceable halogen atoms in the repeat unit have been prepared by one-pot polycondensation at high temperature from dianhydrides and diamines containing halogen atoms. The halogenated polyimides exhibited good thermal properties and great solubility in a wide range of organic solvents, which make them good candidates to prepare functional polymers...
This work reports the flat sheet membrane preparation from syndiotactic polypropylene (sPP) by thermally induced phase separation (TIPS) process. sPP obtained by polymerization using metallocene catalysts and isotactic polypropylene (iPP) also obtained via metallocene catalysis with similar molecular weight were used. The phase diagrams of sPP and iPP with diphenylether as diluent were obtained. The...
Free-standing melanin films were successfully synthesised electrochemically from dopa. The optimum synthetic conditions such as pH, concentration and current were determined, and it was found that free-standing films could only be formed when ITO glass electrodes were used. The films were analysed by solid state NMR and XPS which showed the presence of indolic moieties characteristic of melanin-type...
The counter-ions of montmorillonite have been exchanged for ammonium cations containing either a sulfonic acid or a carboxylic acid in order to improve the performances of sulfonated membranes in direct methanol fuel cell. These layered silicates have been dispersed within Nafion ® by solution mixing. Comparison with conventional organo-modified montmorillonite (Cloisite 30B) shows that the...
The sol–gel polymerization and resulting structures of organic-inorganic systems based on hybrid methacrylate oligomers have been studied using SEC, DSC, and SAXS. The block and random oligomers with narrow polydipersity were prepared by group transfer polymerization. All the oligomers contain 3-(trimethoxysilyl)propyl methacrylates in the chain and form silsesquioxane (SSQO) clusters by hydrolytic...
A new thermoreversible polyimide gel was prepared and characterized. This polyimide was synthesized from 4,4′-oxydiphthalicanhydride (ODPA) and 3,5-diamino-benzonic-4′-diphenyl ester (DABBE) via a one-step polymerization procedure in m-cresol. With lowering temperature, a gel from the polyimide (PI) solution was formed due to the solvation power decrease. On heating, a gel/sol transition could be...
The rheological behavior of nanocomposites based on elastomeric ethylene–propylene (EP) random copolymer (84.3wt% P) and well-dispersed modified carbon nanofibers (MCNFs) with concentrations from 0.5 to 20wt% were studied by oscillatory-shear rheometry at varying temperatures. At relatively low temperatures, the entanglement density of the polymer chains appeared to increase with filler concentration,...
Molecular dynamics simulations of a semi-flexible main chain LCP (liquid crystalline polymer) have been carried out using a newly developed model named solo-LJ-spring-GB model. The new model represents the molecular chain in the form of GB-spring-LJ-spring-…-LJ-spring-GB sections that simplifies the model and reduces the simulation computation by many times. The new model was evaluated by studying...
Stable polyurethane–polystyrene (PU–PS) copolymer emulsions were prepared by the polymerization of 2-hydroxyethyl acrylate (HEA)-capped PU macromonomer and styrene, using azobis(isobutyronitrile) (AIBN), a radical initiator, and 4-((benzodithioyl)methyl)benzoic acid, a reversible addition–fragmentation chain transfer (RAFT) agent. As the molar ratio of the RAFT agent to AIBN increased, the zeta potential...
Two new soluble arylenevinylene-based polymers comprising of an electron-donating carbazole unit and an electron-accepting 2,1,3-benzothiadiazole (or fluorenone) unit in the main chain were synthesized by Heck polycondensation between 3,6-divinylene-9-decyl carbazole and 4,7-dibromo-2,1,3-benzothiadiazole (or 2,7-dibromofluorenone). In the toluene solution, a polymer with benzothiadiazole unit showed...
Polypropylene (PP) was blended with polyoxyethylene nonylphenol (PN) in a twin-screw extruder and injection moulded. The dynamic mechanical properties of PP/PN blends were characterized by dynamic mechanical analyser (DMA). The glass transition temperature (T g ) of PP showed a slight decrease with incorporation of PN. Differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD)...
The chain extension using bisoxazolines (OO) as coupling agent was studied by means of the Monte Carlo (MC) method, focusing on the reaction kinetics. A comparison between simulated results and those calculated by an improved kinetic model was made. The coupling efficiency of the chain extender, average molecular weight and molecular weight distributions (MWDs) were investigated. The results show...
A comprehensive analysis of ductile and brittle failures from creep rupture testing of a wide spectrum of HDPE pipes was conducted. The analysis indicates that the ductile failure of such pipes is primarily driven by the yield stress of the polymer (or pipe). Examination of ductile failure data at multiple temperatures indicates a systematic improvement in performance with increasing temperature....
Biodegradable polymer blends of poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) and poly(ε-caprolactone) (PCL) blends were prepared with the ratio of PHBV/PCL ranging from 80/20–20/80 by co-dissolving the two polyesters in chloroform and casting the mixture. Differential scanning calorimetry (DSC) and optical microscopy (OM) were used to investigate the miscibility and crystallization of PHBV/PCL...
This study is concerned with the finite, large strain deformation behavior of polymeric glasses. True stress–strain curves in uniaxial compression obtained for five different polymeric glasses: polycarbonate, polystyrene, poly(2,6-dimethyl-1,4-phenylene oxide), and linear and cross-linked poly(methylmethacrylate), revealed a strain-hardening response during plastic deformation that is strain-rate...
As integrated circuits have become more and more complex and with smaller and smaller feature sizes several limitations have become apparent. One of these is the need for low-k dielectric materials as insulating layers. Recent work has reported promising materials for such insulators that include some fluorinated polymers. These dielectric materials were further improved by introducing porosity into...
Hydrogels with good mechanical stability are generally obtained by chemical crosslinking. However, the compounds used as crosslinking agents are often highly toxic, and thus they are not recommended as starting materials in view of an environmentally safe production process and a biocompatible product.In this work chemically crosslinked superabsorbent hydrogels have been synthesized from water solutions...
Based on our experiments on polyethylene where we have observed a constant level of plastic resistance, independent of lamella thickness exceeding 40nm, we have fundamentally re-considered the rate controlling mechanisms of crystal plasticity in semi-crystalline polymers. In this we have not only re-examined and made modifications to the widely accepted mechanism of Young (Young RJ. Mater Forum 1988;11:210...
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