Ioan I Negulescu
Louisiana State University, Human Ecology, Faculty Member
- Professor at Louisiana State University in Baton Rouge, LAedit
Abstract: Since polymer modified asphalt cement (PMAC) has been employed for a decade, the lifetime and wear of some of these pavements is reaching a stage where resurfacing will be necessary. This paper considers the potential problems... more
Abstract: Since polymer modified asphalt cement (PMAC) has been employed for a decade, the lifetime and wear of some of these pavements is reaching a stage where resurfacing will be necessary. This paper considers the potential problems associated with recycling ...
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Chemistry of cellulose in ionic liquids has been briefly reviewed and, accordingly, the phthalation of chitosan in these ionic solvents has been investigated. Chitosan (K) has been reacted at 100 °C for 4 hours with phthalic anhydride... more
Chemistry of cellulose in ionic liquids has been briefly reviewed and, accordingly, the phthalation of chitosan in these ionic solvents has been investigated. Chitosan (K) has been reacted at 100 °C for 4 hours with phthalic anhydride (PA) in ionic liquids 1-butyl-3-methylimidazolium acetate (BMIMAc) and 1-butyl-3-methylimidazolium chloride (BMIMCl) in the presence of bases, pyridine and 1,4-diazobicyclo[2.2.2] octane (DABCO), or the phthalation has been catalyzed by N-bromosuccinimide (NBS). Depending on the nature of the reaction components, the samples were prepared with molar ratios of PA to anhydroglucose unit (PA:K) from 3:1 to 10:1, including molar ratios of bases or catalyst to chitosan, ranging also from 3:1 to 10:1. All the reaction products were soluble in dimethyl sulfoxide and dimethylformamide. Both functional groups of chitosan units, -OH and -NH2, reacted, resulting in FTIR confirmed products containing esters, amide, and imide functional groups. Heating the isolated...
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Technical University Iasi , Department of Physics, Copou Nr. 27 , Iasi 6600 , Romania. ... Abstract Linear poly (y-alkyl substituted-a, L-g1utamate)s exhibits interesting thermal and morphological properties in the bulk state. In the... more
Technical University Iasi , Department of Physics, Copou Nr. 27 , Iasi 6600 , Romania. ... Abstract Linear poly (y-alkyl substituted-a, L-g1utamate)s exhibits interesting thermal and morphological properties in the bulk state. In the paper we report on the electrical and thermal ...
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An SBS copolymer modified asphalt cement (PG 76-22) was subjected to accelerated aging using multiple PAV operations in the absence and in the presence of water. A similar polymer modified asphalt cement composition was sampled from a... more
An SBS copolymer modified asphalt cement (PG 76-22) was subjected to accelerated aging using multiple PAV operations in the absence and in the presence of water. A similar polymer modified asphalt cement composition was sampled from a road after up to seven years of ...
Research Interests: Engineering, Organic Chemistry, Carbon, Rheology, Magnetic Resonance Spectroscopy, and 15 moreInfrared spectroscopy, Methylation, Optical microscopy, Physical sciences, Chemical Analysis, CHEMICAL SCIENCES, Humidity, Oxidation, Carrageenan, Food Sciences, Elastic Properties, Copolymers, Carbohydrate Polymers, Chemical Structure, and Fourier transform infrared
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ABSTRACT Ground tyre rubber (GTR) has been employed to modify asphalt binders used in hot-mix asphalt construction since the early 1960s. Proper formulation of GTR-modified asphalt binders provides for substantial improvement in... more
ABSTRACT Ground tyre rubber (GTR) has been employed to modify asphalt binders used in hot-mix asphalt construction since the early 1960s. Proper formulation of GTR-modified asphalt binders provides for substantial improvement in performance over conventional asphalt binders, while providing an outlet for disposal of waste tyres. Physical characteristics of GTR are considered to be vital to the final performance of the asphalt paving mixture, with some state agencies specifying chemical composition requirements for GTR used in binder modification. Adequate analysis and understanding of the functional polymer content, polymer available in GTR to improve asphalt binder properties, and other chemical characteristics of GTR remain lacking. Thermogravimetric analysis (TGA) is a method used to measure the change in mass of a material measured as a function of temperature or time facilitating acquisition of information on properties of the material and its composition. This paper introduces an instrumental TGA method to analyse recycled tyre rubber, also known as ground tyre rubber or GTR, for better understanding and quantification of the functional polymer content, as well as general chemical characteristics, of GTR used to modify asphalt binders.
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To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this... more
To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, USA) at 20 °C. Statistical analysis included descriptive statistics, unpaired t-tests, and Tukey's test to evaluate the mean ± standard deviation for corneal diameter, anterior chamber volume, and aqueous humor viscosity amongst groups and calculation of Spearman's coefficient for correlation analyses. The mean aqueous humor viscosity in the barred owl was 14.1 centipoise (cP) ± 9, cat 4.4 cP ± 0.2, and dog 2.9 cP ± 1.3. The aqueous humor viscosity for the horse was 1 cP. Of the animals evaluated in this study, the raptor aqueous humor was the most viscous. The aqueous humor of the barred owl is significantly more viscous than the dog (P < 0.0001). The aqueous humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer.
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The thermal degradation of certain trioxane-dioxolane copolymers obtained with boron trifluoride-acrylonitrile complex as initiator has been investigated. The thermal stability of samples, discussed in terms of topoenergetic values, was... more
The thermal degradation of certain trioxane-dioxolane copolymers obtained with boron trifluoride-acrylonitrile complex as initiator has been investigated. The thermal stability of samples, discussed in terms of topoenergetic values, was related both to copolymer composition and conversion. The most thermostable copolymers (∼5% weight loss at 300°C in air), having 5–8% dioxolane units, had the highest intrinsic viscosity in the series and
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Abstract The paper describes the synthesis of a multifunctional (ie,-COOH,-OH, tertiary amino) cyclic carbosiloxane compound by the reaction of the epoxy ring attached to the disiloxane moiety with p-aminobenzoic acid. The structure of... more
Abstract The paper describes the synthesis of a multifunctional (ie,-COOH,-OH, tertiary amino) cyclic carbosiloxane compound by the reaction of the epoxy ring attached to the disiloxane moiety with p-aminobenzoic acid. The structure of the resulted product was ...
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... Subramaniam Sathivel Peter J. Bechtel Jerry Babbitt Witoon Prinyawiwatkul Ioan I. Negulescu ... Peter J. Bechtel, PhD, USDA-ARS Scientist, USDA/ARS Seafood Laboratory, 245 O'Neill Building, University of Alaska Fairbanks,... more
... Subramaniam Sathivel Peter J. Bechtel Jerry Babbitt Witoon Prinyawiwatkul Ioan I. Negulescu ... Peter J. Bechtel, PhD, USDA-ARS Scientist, USDA/ARS Seafood Laboratory, 245 O'Neill Building, University of Alaska Fairbanks, Fairbanks, AK 99775. ...
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The coupling efficiency of seven coupling agents in wood-polymer composites (WPC) was investi- gated in this study. The improvement on the interfacial bonding strength, flexural modulus, and other mechanical properties of the resultant... more
The coupling efficiency of seven coupling agents in wood-polymer composites (WPC) was investi- gated in this study. The improvement on the interfacial bonding strength, flexural modulus, and other mechanical properties of the resultant wood fiber/high-density polyeth- ylene (HDPE) composites was mainly related to the cou- pling agent type, function groups, molecular weight, con- centration, and chain structure. As a coupling
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... The latter two cases seemed to be dominant for most composites with a coupling agent ... Figure 5. SEM micrographs for the fracture surfaces of modified wood-fiber/HDPE composites ... Scheme 3. Hypothetical structures of the... more
... The latter two cases seemed to be dominant for most composites with a coupling agent ... Figure 5. SEM micrographs for the fracture surfaces of modified wood-fiber/HDPE composites ... Scheme 3. Hypothetical structures of the woodpolymer interface for melt-blended wood-fiber ...
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We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially... more
We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L- and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate.
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... Characterization of Asphalt Cements ... The physical prop-erties of rubber asphalt binders can be characterized by using a dynamic shear rheometer with an appropriate ... In analyzing the asphalt cements and the related materials, the... more
... Characterization of Asphalt Cements ... The physical prop-erties of rubber asphalt binders can be characterized by using a dynamic shear rheometer with an appropriate ... In analyzing the asphalt cements and the related materials, the complex modulus, G*, reflects the total stiffness ...
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The aim of the present work is to understand how ionic strength of precursor polymer-clay gels influences the final structure of multilayered nanocomposite films fabricated from such gels. We have prepared three aqueous precursor gels... more
The aim of the present work is to understand how ionic strength of precursor polymer-clay gels influences the final structure of multilayered nanocomposite films fabricated from such gels. We have prepared three aqueous precursor gels containing 3wt\% LRD, 2wt\% PEO ...
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Periodic patterns resembling spirals were observed to form spontaneously upon unassisted cooling of d-glucaric acid- and d-galactaric acid-based polyamide solutions in N-methyl-N-morpholine oxide (NMMO) monohydrate. Similar observations... more
Periodic patterns resembling spirals were observed to form spontaneously upon unassisted cooling of d-glucaric acid- and d-galactaric acid-based polyamide solutions in N-methyl-N-morpholine oxide (NMMO) monohydrate. Similar observations were made in d-galactaric acid-based polyamide/ionic liquid (IL) solutions. The morphologies were investigated by optical, polarized light and confocal microscopy assays to reveal pattern details. Differential scanning calorimetry was used to monitor solution thermal behavior. Small- and wide-angle X-ray scattering data reflected the complex and heterogeneous nature of the self-organized patterns. Factors such as concentration and temperature were found to influence spiral dimensions and geometry. The distance between rings followed a first-order exponential decay as a function of polymer concentration. Fourier-Transform Infrared Microspectroscopy analysis of spirals pointed to H-bonding between the solvent and the pendant hydroxyl groups of the gluc...
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A novel route to fabricate low-cost porous carbon nanofiber (CNF) composed of biomass tar, polyacrylonitrile (PAN), and silver nanoparticles with antimicrobial capabilities was demonstrated through electrospinning and subsequent... more
A novel route to fabricate low-cost porous carbon nanofiber (CNF) composed of biomass tar, polyacrylonitrile (PAN), and silver nanoparticles with antimicrobial capabilities was demonstrated through electrospinning and subsequent stabilization and carbonization processes. Continuous and bead-free electrospun nanofibers were obtained with average diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased average diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the resultant CNFs showed more uniformly sized and reduced average diameters (226-507 nm) compared to the as-spun nanofibers. In addition, the combined effects of phase separations of the tar and PAN and thermal decompositions of some tar constituents endowed the tar containing CNFs with higher specific surface areas (>400 m2/g) and microporosity. These pore characteristics increased the exposures and ...
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... the gelling and high surface area characteristics of Laponite with the large-aspect-ratio ... In this study Laponite-RD (LRD), a synthetic Hectorite type clay, and Montmorillonite ... Frequency dependent oscillatory shear experiments... more
... the gelling and high surface area characteristics of Laponite with the large-aspect-ratio ... In this study Laponite-RD (LRD), a synthetic Hectorite type clay, and Montmorillonite ... Frequency dependent oscillatory shear experiments of LRDXCNA(3 − X)PEO2 samples are presented ...
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ABSTRACT The anaerobic biodegradability of Polyhydroxybutyrate (PHB) was investigated to determine degradation kinetics and the effects of degradation on characteristics of the plastic. PHB was melt-pressed into plates of thicknesses... more
ABSTRACT The anaerobic biodegradability of Polyhydroxybutyrate (PHB) was investigated to determine degradation kinetics and the effects of degradation on characteristics of the plastic. PHB was melt-pressed into plates of thicknesses 0.24, 0.5, 1.2, 3.5 and 5.0 mm. Three experiments, which assessed biodegradability based on evolved gaseous carbon, were performed according to ASTM D 5210. In addition, two mass loss studies were performed to facilitate the determination of degradation kinetics. Melt-pressed plates of the PHB were extracted from the degrading medium and weighed at appropriate time intervals for determining the degradation kinetics. In the mass-loss experiments, melt-pressed plates of the bioplastic with five different initial mass-to-surface-area ratios were investigated for the purpose of establishing a relationship between this parameter and decay rate coefficients for first order decay kinetics. It was found that the degradation rate coefficient of the PHB is dependent upon the initial mass-to-surface-area ratio of the bioplastic seemingly according to saturation kinetics. In the first anaerobic mass loss experiment, the degradation rate coefficients with respect to initial surface area of the 0.5-mm, 1.2-mm, and 3.5-mm PHA plates were 0.5846, 1.2920, and 2.0656 mg cm-2 d-1, respectively; in the second anaerobic mass loss experiment, the degradation rate coefficients with respect to initial surface area of the 0.24-mm, 1.2-mm, and 3.5-mm PHA plates were 0.3191, 0.7308, and 0.9484 mg cm-2 d-1, respectively. This data also demonstrated that the particular sewage sludge medium used to degrade the PHB has a significant impact on the degradation kinetics. Furthermore, the effects of biodegradation on certain characteristics of the bioplastic as determined by analyses such as DSC, FT-IR, and Size Exclusion Chromatography were tested.
Composite nonwovens have been prepared from bagasse and cotton fibers and a series of synthetic and biobased polymers, such as poly(tetramethylene adipate-co-terephthalate) and poly(hydroxy butyrate). Some nonwoven compositions have been... more
Composite nonwovens have been prepared from bagasse and cotton fibers and a series of synthetic and biobased polymers, such as poly(tetramethylene adipate-co-terephthalate) and poly(hydroxy butyrate). Some nonwoven compositions have been treated with flame retardants containing phosphorus or boron which might act aggressively on the development of microbial colonies responsible for biodegradation. For other compositions the presence of plasticizers used for
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A series of new, fluorinated poly(ester-imides)s has been synthesized by solution condensation, in a high-boiling-point solvent, of dihydroxy compounds containing imide and hexafluoroisopropylidene units with diacid chlorides containing... more
A series of new, fluorinated poly(ester-imides)s has been synthesized by solution condensation, in a high-boiling-point solvent, of dihydroxy compounds containing imide and hexafluoroisopropylidene units with diacid chlorides containing preformed ester groups. Solutions of these polymers in NMP or in a mixture of trifluoroacetic acid with chloroform were cast into colourless, thin, flexible films having a low dielectric constant. These polymers
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Page 1. ABIOTIC SYNTHESIS AND THE PROPERTIES OF SOME PROTOBIOCOPOLY MERS C. I. SIMIONESCU, F. DkNES, and I. NEGULESCU Petru Poni Institute of Macromolecular Chemistry, Jassy, Romania SYNOPSIS ...
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The plant derived polyesters, better known as polyhydroxyalkanoates, PHAs, are renewable and sustainable: [-O-CH(CH3)-(CH2)x-CO-]n. If x = 0 PHA is Poly(lactic acid), PLA; if x = 1 or 2 it is Poly(hydroxy butyrate), PHB, or Poly(hydroxy... more
The plant derived polyesters, better known as polyhydroxyalkanoates, PHAs, are renewable and sustainable: [-O-CH(CH3)-(CH2)x-CO-]n. If x = 0 PHA is Poly(lactic acid), PLA; if x = 1 or 2 it is Poly(hydroxy butyrate), PHB, or Poly(hydroxy valerate), PHV. SEC and light scattering have been used before for determination of the absolute molecular mass of PLA dissolved in CHCl3 (Malmgren et
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Mixtures of poly(methyl-a-cyanoacrylate), PMCA, and poly(allyl-a-cyanoacrylate), PACA, were precipitated or casted from solutions and their compatibility was estimated by optical microscopy and thermogravimetry. The paper establishes the... more
Mixtures of poly(methyl-a-cyanoacrylate), PMCA, and poly(allyl-a-cyanoacrylate), PACA, were precipitated or casted from solutions and their compatibility was estimated by optical microscopy and thermogravimetry. The paper establishes the range of optimum compatibility ratios and discusses the thermal behaviour of the obtained PMCA/PACA blends and of copolymers of similar composition.
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... XI.-CHEM., A24(1), pp. 75-83 (1987) THERMAL BEHAVIOR OF POLY [cx-CYANOACRYLATE) S IOAN I. NEGULESCU, ELENA-MARIA CALUCARU, CORNELIA VASILE, and GHEORGHE DUMITRESCU ... Page 3. THERMAL BEHAVIOR OF PO LY (a-CYANOACRY LATE)S 77 ...
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The copolymerization of four Schiff bases (substituted benzylidine anilines) with tetracyanoethylene has been investigated. The reaction takes place in the absence of an initiator through a zwitterionic mechanism, leading to copolymers... more
The copolymerization of four Schiff bases (substituted benzylidine anilines) with tetracyanoethylene has been investigated. The reaction takes place in the absence of an initiator through a zwitterionic mechanism, leading to copolymers with an almost alternating structure. When dimethylformamide was used as solvent, a concurrent radical homopolymerization of tetracyanoethylene with the formation of an azoporphyrin structure occurs.
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... The Differential Scanning Calorimetry Study of Asphalt Crystallinity WILLIAM H. DALY, ZHAOYAO QIU, AND IOAN NEGULESCU ... Page 7. 60 TRANSPORTATION RESEARCH RECORD 1535 3. Brûlé, B., JP Planche, G. King, P. Claudy, and JM Letoffe. ...
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The thermally stimulated depolarization current method and the thermally stimulated polarization current method have been used for the study of the star poly (γ-stearyl-α, L-glutamate) polymer. The β peak appears around -88°C and is... more
The thermally stimulated depolarization current method and the thermally stimulated polarization current method have been used for the study of the star poly (γ-stearyl-α, L-glutamate) polymer. The β peak appears around -88°C and is determined by side-dipole moments. Three other peaks appear: α1, α1', and α2. The activation energy was determined for β and α2 peaks for different heating rates.
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Thermally stimulated depolarization current (TSDC) and thermally stimulated polarization current (TSPC) measurements and the differential scanning calorimetry (DSC) method have been used for the investigation of thermal transitions in... more
Thermally stimulated depolarization current (TSDC) and thermally stimulated polarization current (TSPC) measurements and the differential scanning calorimetry (DSC) method have been used for the investigation of thermal transitions in thermotropic poly(γ-stearyl-α, L-glutamate). The β peak (-80°C) and α1 and α'1 peaks registered between -50°C and 25°C were attributed to movements of side chain dipoles. The α2 peak, observed ≈43°C, was
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... Characterization of Asphalt Cements ... The physical prop-erties of rubber asphalt binders can be characterized by using a dynamic shear rheometer with an appropriate ... In analyzing the asphalt cements and the related materials, the... more
... Characterization of Asphalt Cements ... The physical prop-erties of rubber asphalt binders can be characterized by using a dynamic shear rheometer with an appropriate ... In analyzing the asphalt cements and the related materials, the complex modulus, G*, reflects the total stiffness ...
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DOI: 10.1177/004051750007000101 2000 70: 1 Textile Research Journal and Frank S. Denes ... Ioan I. Negulescu, Simona Despa, Jonathan Chen, Billie J. Collier, Mircea Despa, Agnes Denes, Majid Sarmadi Characterizing Polyester Fabrics... more
DOI: 10.1177/004051750007000101 2000 70: 1 Textile Research Journal and Frank S. Denes ... Ioan I. Negulescu, Simona Despa, Jonathan Chen, Billie J. Collier, Mircea Despa, Agnes Denes, Majid Sarmadi Characterizing Polyester Fabrics Treated in Electrical Discharges ...