Property transitions in high‐density polyethylene/maleated poly(ethylene–octene)/calcium carbonate ternary composites

Ternary composites of high‐density polyethylene (HDPE)/maleated poly(ethylene–octene) (POE‐g)/calcium carbonate (CaCO₃) were prepared by the melt extrusion process. Crystallization behavior investigation and mechanical properties study showed that there existed a transition in both crystallization temperature (T_c) and impact strength of ternary composites. These transitions were attributed to the development of morphology, with variation of concentration of POE‐g in ternary composites. The strength of interfacial adhesion also influenced the property transitions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3361–3366, 2006     

Kinetic Analysis of the Hydrocarbon Total Oxidation Using Individually Measured Adsorption Isotherms

The partial and total oxidation of C₂H₄, C₃H₆ separately and in mixtures, and CO on a CrO_x/γ‐Al₂O₃ catalyst was studied to describe the reaction kinetics. Based on catalytic cycles mechanistic kinetic models of all reactions were derived. For reduction of adjustable parameters individually measured adsorption isotherms were used to parameterize adsorption constants in the kinetic models. The complex reaction network was decomposed in three sub‐networks to support parameter estimation, to quantify and validate kinetic rate approaches. The best fit for hydrocarbon reactions was achieved by an Eley‐Rideal and for CO by a Mars‐van Krevelen approach.     

Wavelength‐shift fluorescent probes for monitoring of polymerization

The feasibility of using wavelength‐shift fluorescent probes for cure monitoring of an epoxy resin and an acrylic resin was evaluated. 4‐(N,N‐dihexylaminostyryl)‐4′‐pyridinium propylsulfonate (DHASP‐PS), as well as each of other wavelength‐shift fluorescent probes, was dissolved in the epoxy resin, a stoichiometric mixture of diglycidyl ether of bisphenol A and 4,4′‐methylene‐bis(cyclohexylamine). The fluorescence and the excitation spectra of each of the probes dissolved in the epoxy resin were then measured at various times during the cure of the epoxy resin at 60°C. The fluorescence and the excitation spectra of the probe DHASP‐PS dissolved in methyl methacrylate (MMA) were also measured at various times during the cure of the acrylic resin at 55°C. Since the peak fluorescence wavelength of each of the wavelength‐shift fluorescent probes decreased during the cure of the epoxy resin or MMA, these fluorescent probes can be used for monitoring the polymerization reactions of epoxy resins and vinyl resins. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 747–750, 2006     

Hydrogen bonding interactions of styrene‐maleimide copolymers with diaminotriazine derivatives

Poly(styrene‐co‐N‐maleimide) precursor and poly(styrene‐co‐N‐maleimide)‐block‐polystyrene have been synthesized by quasiliving radical polymerization. Low molecular weight compounds with the sites specific for the complementary binding to the maleimide moieties via triple hydrogen bonds, 2,4‐diamino‐6‐n‐alkoxy(C‐4, C‐8, and C‐12)‐s‐triazines, have been prepared. Hydrogen bonding between diaminotriazine and maleimide units in the copolymer–diaminotriazine mixtures has been investigated by FTIR. Microphase separated structure in the block copolymer‐diaminotriazine mixtures has been confirmed by DSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2338–2346, 2006     

Graft copolymerization of methyl acrylate onto chitosan initiated by potassium diperiodatoargentate (III)

A novel efficient redox system—potassium diperiodatoargentate [Ag(III)]‐chitosan—was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in aqueous alkali solution. The effects of reaction variables such as monomer concentration, initiator concentration, reaction time, and temperature were investigated and the grafting conditions were optimized. The structures and the thermal stability of chitosan and chitosan‐g‐PMA were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). The solubility of chitosan‐g‐PMA in some mixed solvent was tested. The graft copolymer was shown to be an effective compatibilizer in blends of poly(vinyl chloride) (PVC) and chitosan. Finally, a mechanism is proposed to explain the formation of radicals and the initiation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 799–804, 2006     

Pervaporation properties of polypyrrolidinone‐based membranes for EtOH/ETBE mixtures separation

The separation of ethanol/ethyl‐tertiobutylether mixtures by pervaporation was studied with new membranes prepared from N‐vinyl‐pyrrolidinone (NVP) and N‐[3‐(trimethylamoniopropyl)]methacrylamidemethylsulfate) (TMA). The pervaporation results showed that highly EtOH selective membranes could be obtained from PVP blends and from pyrrolidinone‐based crosslinked copolymers. The influences of the polymer blend composition and the role of the polymer microstructures on the membrane properties were investigated. Whatever the exact NVP/TMA composition used, the membranes strongly favored the pervaporation of ethanol. The ethanol selectivity was higher for the lower PVP/TMA ratio. On the one hand, these results were ascribed to the high pyrrolidinone residues content, which is responsible of the enhanced EtOH sorption affinity. The observed permeation selectivity was in agreement with the swelling data also recorded with the different polymers, showing higher affinity for ethanol with PVP‐enriched materials compared with TMA ones. This is a direct consequence of the Lewis base feature of pyrrolidinone sites towards EtOH molecules. On the other hand, the TMA residues improved the overall stability and selectivity of the membranes thanks to crosslinking reactions, which were induced by thermal treatment. A close comparison made between polymer blend and copolymer pervaporation results helped to clarify the TMA role of the membrane transport properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3622–3630, 2006     

Hydrosilylation reaction of methylhydridesiloxane to phenylacetylene

The hydrosilylation reaction of α,ω‐bis(trimethylsiloxy)methylhydridesiloxane to phenylacetylene in the presence of catalyst—platinum hydrochloric acid (0.1M solution in tetrahydrofuran)—at 1 : 35 ratio of initial compounds, at various temperatures (40–60°C) was investigated and methylsiloxane oligomers with phenethenyl substituted groups in the side chain has been obtained. It was shown that complete hydrosilylation of all active (Si? H groups do not take place. The hydrosilylation reaction order, activation energy, and rate constants were found. The synthesized oligomers were characterized by ¹H and ¹³C NMR and IR spectral data. Gel‐permeation chromatographic, differential scanning calorimetric, thermogravimetric, and wide‐angle X‐ray investigations of synthesized oligomers were carried out. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2511–2515, 2006     

Modification of preparation method for polymer inclusion membrane (PIM) to produce hollow fiber PIM

A new preparation method for polymer inclusion membrane (PIM) was developed. The preparation method—called post‐treatment method—is very convenient to prepare a hollow fiber PIM. Using this method, a commercial cellulose triacetate (CTA) hollow fiber membrane can be easily converted into a hollow fiber PIM. Thus, a CTA hollow fiber membrane was allowed to swell in 2‐nitrophenyl‐n‐octyl ether (NPOE) in the presence of chloroform as a solvent for CTA and N,N,N′,N′‐tetraoctyl‐3‐oxapentane diamide (TODGA) as a carrier. After evaporating chloroform, a hollow fiber PIM containing NPOE and TODGA was obtained. The result of the transport experiment of cerium(III) ions using the hollow fiber PIM showed that cerium ions were effectively transported from the feed solution to the strip solution through the hollow fiber PIM, indicating that the hollow fiber PIM was successfully prepared using the post‐treatment method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4372–4377, 2006     

Effects of low molar mass additives on the molecular mobility and transport properties of polysulfone

The aim of this work was to study the effects of incorporation of low molar mass additives on the molecular mobility and water vapor transport properties of the polysulfone (PSF). The additives used in this work were N‐phenyl‐2‐naphthylamine (PNA) at 10, 18, and 30 wt % concentration and 2,6‐di‐terc‐butyl p‐cresol (BHT) at 5, 10, 15, and 20 wt % concentration. The additive incorporation resulted in changes on molecular mobility and thermal properties of the polysulfone glassy matrix associated with antiplasticization phenomenon. The effects observed on the polysulfone were reduction in glass transition temperature, reduction in the magnitude of secondary loss transition peak, changes in secondary loss transition peak for higher temperatures, and increase in elastic modulus E′ as compared with those of the unmodified polymer. Changes in molecular mobility were correlated to reductions in PSF water vapor permeability. In PSF–PNA mixtures, the water vapor permeability was reduced up to 95% for 30 wt % additive incorporation and 81% for mixtures PSF–BHT with 20 wt % incorporation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 825–832, 2006     

Reversible Control of Exo‐ and Endo‐Budding Transitions in a Photosensitive Lipid Membrane

We have developed a method for the photomanipulation of lipid membrane morphology in which the shape of a vesicle can be switched by light through the use of a synthetic photosensitive amphiphile containing an azobenzene unit (KAON12). We prepared cell‐sized liposomes from KAON12 and 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) and conducted real‐time observations of vesicular transformation in the photosensitive liposome by phase‐contrast microscopy. Budding transitions—either budding toward the centre of the liposome (endo‐bud) or budding out of the liposome (exo‐bud)—could be controlled by light. We discuss the mechanism of this transformation in terms of the change in the effective membrane surface area due to photoisomerization of the constituent molecules.     

Structure‐property relationships of blends of polycarbonate

Three grades of bisphenol‐A polycarbonate—high molecular weight linear, high molecular weight branched and low molecular weight linear—and their blends have been studied by GPC, DMTA, DSC, rheometry and impact measurements. The molecular weight distribution of the blends agred with that predicted from the component's distributions, indicating that no transesterification reactions had occurred during melt blending. The T_g of the blends varied with blend composition according to the Fox equation and was related to the reciprocal molecular weight predicted by the Flory‐Fox equation. The low shear rate viscosity of the blends agreed with a logarithmic rule of mixtures and showed power‐law dependence on the weight average molecular weight. At higher shear rates, shear thinning was observed. The steady shear viscosity correlated well with the dynamic viscosity, as suggested by the Cox‐Merz relation. The stress relaxation behavior of the melt was very sensitive to the blend composition and molecular weight and correlated well with the real modulus. Temperature studies of the dart impact energy showed that only the low molecular weight polymer underwent a brittle‐duetile transition at ea ?30°C and that all the blends were tough at room temperature. The enhanced stress triaxiality inherent in the notched lzod test caused the impact strenght at room temperature to decrease almost linealy with blend composition.     

Rheological study of the curing kinetics of epoxy–phenol novolac resin

The curing reaction of an epoxy–phenolic resin under different conditions was monitored using rheological measurements. The evolution of viscoelastic properties, such as storage modulus, G′, and loss modulus, G″, was recorded. Several experiments were performed to confidently compare the rheological data obtained under varied curing conditions of temperature, catalyst concentration, and reactive ratios. The values of G′ measured at the end of the reactions (at maximum conversion) were independent of the frequency and temperature of the tests in the range of high temperatures investigated. The overall curing process was described by a second‐order phenomenological rheokinetic equation based on the model of Kamal. The effects of the epoxy‐to‐phenolic ratio as well as the curing temperature and the catalyst concentration were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4430–4439, 2006     

Investigation of Pluronic© F127–Water solutions phase transitions by DSC and dielectric spectroscopy

The water solutions of the block copolymers PEO_n‐PPO_m‐PEO_n, known as pluronics, show a complex thermal behavior, since they are liquid at low temperature (5°C), and they can give soft gel when heated at body temperature (37°C). These properties are of great interest in biomedical applications. To properly design these applications, a prerequisite is the knowledge of the thermodynamics—how much—and of the kinetics—how fast—with which these transformations take place. In this work, solutions of F127 (the copolymer for which n = 100 and m = 65) were studied by varying the concentration and the temperature and analyzing their behavior when heated under several heating rates. The studies were performed by differential scanning calorimetry (DCS) and dielectric spectroscopy. The investigations carried out under equilibrium conditions allowed us to determine the thermodynamics of the phase transitions, whereas the investigations carried out under varying conditions allowed us to quantify the kinetics of the phase transitions. Empirical models were also proposed to describe both the thermodynamics and the kinetics observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal analysis and mechanical characterization of maleimide‐functionalized benzoxazine/epoxy copolymers

Maleimide‐functionalized benzoxazine is copolymerized with epoxy to improve toughness and processibility without compromising the thermal properties. The incorporation of maleimide functionality into the benzoxazine monomer results in a high performance polymer. All three possible polymerization reactions are confirmed using Fourier transform infrared (FT‐IR) spectroscopy. While maleimide‐functionalized benzoxazine has a glass transition temperature, T_g, of 252°C, a further 25°C increase of T_g is observed when copolymerized with epoxy. The flexural properties are also measured, and the copolymers exhibit a flexural modulus of 4.2–5.0 GPa. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1670–1677, 2006     

Determination of kinetics of CO2 absorption in solutions of 2‐amino‐2‐methyl‐1‐propanol using a microfluidic technique

The kinetics for the reactions of carbon dioxide with 2‐amine‐2‐methyl‐1‐propanol (AMP) and carbon dioxide (CO₂) in both aqueous and nonaqueous solutions were measured using a microfluidic method at a temperature range of 298–318 K. The mixtures of AMP‐water and AMP‐ethylene glycol were applied for the working systems. Gas‐liquid bubbly microflows were formed through a microsieve device and used to determine the reaction characteristics by online observation of the volume change of microbubbles at the initial flow stage. In this condition, a mathematical model according to zwitterion mechanism has been developed to predict the reaction kinetics. The predicted kinetics of CO₂ absorption in the AMP aqueous solution verified the reliability of the method by comparing with literatures’ results. Furthermore, the reaction rate parameters for the reaction of CO₂ with AMP in both solutions were determined. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4358–4366, 2015     

Effects of Monoacylglycerols on Kinematic Viscosity and Cold Filter Plugging Point of Biodiesel

Biodiesel is an alternative fuel composed of mono‐alkyl fatty acid esters made from the transesterification of plant oils or animal fats with methanol or ethanol. After conversion, biodiesel may contain trace concentrations of unconverted monoacylglycerols (MAG). These MAG have low solubility in biodiesel and may form solid residues when stored at cold temperatures. The present study evaluates the measurement of kinematic viscosity (ν) and cold filter plugging point (CFPP)‐time to filter (Δt) as parameters that predict the temperature where small concentrations of MAG may lead to formation of solids or other phase transitions that restrict the flow of soybean oil fatty acid methyl esters (SME) through filters and fuel lines. Mixtures of SME doped with MAG were prepared and ν and Δt were measured as the temperature decreased from 20 to below 0 °C. Results showed a correlation between ν and Δt that held for neat SME (SME without added MAG) and SME‐MAG mixtures as the temperature decreased to the threshold temperature (T_th). Sharp increases in Δt disrupted the correlation as temperature decreased below T_th. Furthermore, T_th generally increased as added MAG concentration increased in the mixtures.     

Compatibility of PTET‐60/CA blends and separation performance of their membranes for benzene/cyclohexane mixture by pervaporation

Aromatic copolyester of poly(trimethylene‐co‐ethylene terephthalate) (PTET) with different composition was synthesized and the PTET sample with 60% weight fraction of polytrimethylene (PTET‐60) was amorphous. The compatibility of PTET‐60/cellose acetate (CA) blends and the pervaporation of their membranes for separation of benzene/cyclohexane mixtures were investigated. It was found that PTET‐60 is compatible with CA when the weight fraction of PTET‐60 in PTET‐60/CA blends (W_PTET‐60) is lower than 0.35 and more than 0.5. Both the degree of swelling (DS) and the permeation flux (J) of these blend membranes increased with increasing W_PTET‐60 from 0 to 0.35, and a maximum value of the separation factor (α) displayed at W_PTET‐60 = 0.25. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2832–2838, 2006     

Some Iron(III) Catalyzed Michael Reactions of Chiral Donors,bis‐Donors,and a bis‐Acceptor

Michael reactions of β‐keto esters 1a—1h with methyl vinyl ketone ( 2a ) catalyzed by FeCl₃ · 6 H₂O (5 mol%) proceed with up to 99% yield. Conversion of β‐keto esters 1a—1e derived from chiral alcohols with 2a result in only very low diastereoselectivities (max. de 20%). A bis‐β‐keto ester 1i and a bis‐vinyl ketone 2b — both valuable monomers for poly‐Michael reactions — are synthesized from common starting materials in up to gram quantities.     

Ethylene and 1‐hexene sorption in LLDPE under typical gas‐phase reactor conditions: Experiments

The sorption of ethylene and 1‐hexene and their mixture in three poly(ethylene‐co‐1‐hexene) samples is measured gravimetrically at temperatures 70, 90, and 150°C and pressures 0–30 bar. Gravimetric sorption measurements are supplemented with microscopic observations of swelling of polyethylene particles caused by sorption and the extent of swelling is found to be significant. Experimental data are compared with predictions of PC‐SAFT (perturbed chain—‐statistical associating fluid theory) equation of state. Comparison of sorption data in semicrystalline polymer (measured at 70 and 90°C) and amorphous polymer (at 150°C) demonstrates the constraining effect of semicrystalline structure. Solubilities of penetrants in investigated samples are not observed to depend on the content of 1‐hexene in copolymers. The solubility of the mixture of ethylene and 1‐hexene is smaller than the sum of solubilities of individual components at 70 and 90°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1124–1136, 2006