bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photochemical reactions of polymers bearing chalcone residues
Authors: Akelah A. , Selim A. , Salah Ei‐Deen N. , Kandil S. H. 
Published: April 2007

AbstractPhotosensitive polymers based on pendent chalcone moieties were prepared directly by radical polymerization of vinyl‐chalcone monomers. The monomers were synthesized by the esterification reactions of the hydroxyl groups of 4‐ and 4′‐hydroxychalcones with methacryloyl chloride. The monomers (4‐ and 4′‐(methacryloyloxy)chalcones) were polymerized to give the corresponding homo‐and co‐polymers containing different ratios of p‐nitrophenyl methacrylate as photosensitizer group.Investigation of the photosensitivities of the chalcone polymers was carried out through study of the photochemical reactions on exposure to UV light and measuring the changes in UV spectra before and after irradiation. The results obtained from the disappearance rates of the C=C bonds indicate that the photoreactivities of the polymers are largely affected by the position of the attachment of the chalcone to the polymer backbone and by the concentration of the photosensitizer group.
Adhesion of polymers to reinforcing fibres
Authors: Hampe A. , Marotzke C. 
Published: April 2007

AbstractA single fibre pull out technique is presented which makes it possible to measure the strength in the interface between fibre and polymer with high precision even if the embedded length of the fibre is short. The method allows measurements for all kinds of fibres in thermoplastic or thermosetting polymers.The effect of fibre surface treatment can be investigated as well as the effect of morphology or internal stresses in the polymer. Examples are given.The shear strength results are compared with results of tensile shear tests performed on symmetrically notched unidirectional reinforced composite samples. The correlation is good and it is shown that the new single fibre pull out method is able to give a better discrimination between the composites than other methods.An analysis of mechanical stress induced during the pull out demonstrates the use and limitation of this method.
Electrical properties of Cu(II) and Ni(II): N‐salicylidene polymethacrylic acid hydrazide complexes
Authors: Ramadan T. A. , Kandil S. H. , Salah H. , Iskander M. F. 
Published: April 2007

AbstractDifferent types of chelated polymer complexes have been synthesized to obtain improved electrical properties. Compact discs from powders of the chelated polymers were prepared and heated in a specially designed holder. Electrical conductivity and dielectric constant of Cu(II) and Ni(II): N‐salicylidene polymethacrylic acid hydrazide samples were measured at a fixed frequency (1600 Hz) throughout the temperature range 25‐150°C.The AC conductivity as well as dielectric measurements showed maxima at 85°C. The water molecules which were trapped in the polymer matrix are believed to play the main role in conduction and dielectric behaviour of the polymeric material. From the AC conductance and dielectric constant measurements, the dielectric losses of these polymeric materials were calculated as a function of temperature.
Studies on lignin‐based adhesives for plywood panels
Authors: Mittal Mradula , Sharma Chandra B. 
Published: April 2007

AbstractLignin, a naturally occurring polymer, was isolated from sawdust and used as a substitute in phenol formaldehyde resins. Thus lignin‐phenol formaldehyde adhesives for plywood with lignin‐phenol ratios of 50:50, 60:40, 70:30, 80:20 and 90:10 were prepared. Glue shear strength for these adhesives was tested by preparing three‐ply plywood panels. The adhesives showed a dry bond strength varying from 0.57 to 0.82 MPa. The glue shear strength for cold water resistance tests varied from 0.16 to 0.25 MPa, indicating that even 80% replacement of phenol with lignin is capable of producing a bond quality acceptable for cold water resistant grade plywood.
Molecular arrangement and polymerizability of n‐alkyl acrylates in langmuir‐blodgett films
Authors: Shiozawa Toyoshi , Shibasaki Yoshio , Fukuda Kiyoshige 
Published: April 2007

AbstractLangmuir‐Blodgett (LB) films of n‐alkyl acrylates with different chain lengths have been investigated with respect to the molecular arrangement and their polymerizability. X‐ and Y‐types of depositions were obtained depending on surface pressures and temperatures. In the case of acrylate monomers with even‐numbered carbon chains polarized IR spectra revealed that X‐type LB films prepared at lower pressures gave uniaxial orientation while Y‐type films at higher pressures biaxial, although X‐ray diffraction of LB films indicated non‐alternating head‐to‐tail structure irrespective of the deposition types. The uniaxial films with rotational freedom exhibited high polymerizability, whereas the biaxial films with closely packed arrangement showed low reactivity. With odd‐numbered nonadecyl acrylate both types of LB films exhibited similar molecular arrangement and polymerizability.
Crazing of polycarbonate at cryogenic temperature: Effect of specimen thickness
Authors: Shonaike G. O. , Reed P. E. 
Published: April 2007

AbstractPolycarbonate sheets of varying thickness were subjected to tensile testing in a nitrogen environment at 77 K. Crazes were detected in the thinnest specimens, but the tendency to craze diminished with increasing specimen thickness. Diffusion of the environment into the skin layer of the specimen, as a proportion of the total thickness of the stressed system, is considered to have a major effect on the probability of crazing. A sandwich model, consisting of plasticized skin layer through diffusion of the environment and unplasticized core, is developed to account for the observations.
In‐source and post‐irradiation polymerization of acenaphthylene in the solid state
Authors: Kücükyavuz Savas , Ülkem Iihan , Göksel Cemile 
Published: April 2007

AbstractRadiation‐induced solid state polymerization of acenaphthylene was studied by using 60Co γ‐rays. The extent of polymerization at room temperature reached 68% when acenaphthylene was irradiated with a dose of 2–5 MGy. Prolonged exposure to the radiation decreased the molecular weight of the polymers. The post‐polymerization of acenaphthylene was found to occur at relatively high temperatures close to the melting point of acenaphthylene. Absence of an effective termination step allows the enhancement of post‐polymerization at higher temperatures after a limiting conversion is accomplished.
Semi‐batch Processes for Emulsion Polymerisation
Authors: Li B. , Brooks B. W. 
Published: April 2007

AbstractEssential features and advantages of semi‐batch emulsion polymerisation are described. Variations of polymerisation rate, polymer particle number, particle size, copolymer composition and molecular weight distribution are considered and the use of mathematical models is reviewed. Suggestions for future work, both experimental and modelling, are made.
An explanation of the solubility behaviour of cellulose acetate in various solvents in terms of supermolecular structure formed by introduction of a substituent group into the glucopyranose unit
Authors: Okajima Kunihiko , Kowsaka Keisuke , Kamide Kenji 
Published: April 2007

AbstractAn attempt is made to explain the solubility behaviour of cellulose derivatives with hydrophobic substituent groups towards several solvents in terms of supermolecular structure concepts, such as the degree of breakdown in intramolecular hydrogen bonds and conformational variety in the C1—O—C4 glucoside linkage, which depend on the total degree of substitution 〈〈F〈〈 and the distribution of substituent groups in the anhydroglucose (AHG) unit 〈〈fk〈〈 (k = 2, 3, and 6), and solvation.For this purpose, cellulose acetate (CA) samples with a wide range of 〈〈F〈〈 values were synthesized and the dependence of supermolecular structural parameters, including Xam(Ck) (k = 3, 6) (degree of breakdown in intramolecular hydrogen bond at Ck position) and Δ1/2(Ck)(k = 1,6) (half value width of Q. carbon NMR peak), on 〈〈F〈〈 or (〈fk〈〈 was investigated. It has been shown that a considerable breakdown in O3—H—O'5 hydrogen bond or allowance of wide variation in chain conformation around the C1—O—C'4 linkage is a minimum condition necessary for CA to dissolve in solvents, irrespective of type of solvent. Water‐solubility of CA is mainly governed by the supermolecular structure induced by the introduction of substituents at the C3 position and number of residual hydroxyl groups at the C6 position. Acetone‐solubility of CA is mainly governed by solvation of the side chain but an intramolecular interaction between acetyl groups and ring oxygen bonds tends to hinder its solubility at high values of 〈〈F〈〈. DMSO behaves as an amphoteric solvent solvating both hydroxyl and O‐acetyl groups in CA molecules.
Synthesis and Characterization of Some Novel Poly(nitroarylates)
Authors: Mansour El‐Sayed M. E. , Kandil Sherif H. , Soliman Mohamed E. M. , Ibrahim Moustafa 
Published: April 2007

AbstractVarious types of poly(nitroarylates) (8–17) were prepared using interfacial polycondensation (IPC) and solution polycondensation (SPC) of 5‐nitroiso‐phthaloyl chloride (la) and 2‐nitroterephthaloyl chloride (2a) with different bisphenols: hydroquinone (3), resorcinol (4), 4.4′‐dihydroxydiphenyl (5), 2,2‐bis(4‐hydroxyphenyl) propane (6) and bis(4‐hydroxyphenyl) sulfone (7). A nitro group was introduced in the polymeric chain in order to improve the properties, solubility and thermal stability of these polymers. Some of the factors affecting the IPC were studied, such as the effect of concentration of the initial components and the role of the solvent. The structures of the poly(nitroarylates) (8–17) were confirmed by elemental analysis, infrared and proton magnetic resonance spectrometry. Thermomechanical analysis (TMA) and thermogravimetric analysis (TGA) of the synthesized polymers were also studied.
Structural analysis of electron beam irradiated ethylene‐vinyl acetate copolymer (EVA) film (II)
Authors: Matsui Toshiro , Shimoda Mitsuya , Osajima Yutaka 
Published: April 2007

AbstractThe crosslinked structure of irradiated ethylene‐vinyl acetate copolymer (EVA) film was examined by means of ESR, IR and pyrolysis‐gas chromatography. The ESR spectrum of 35 Mrad irradiated EVA film with 95g kg−1 vinyl acetate content consisted of a three‐line component with an intensity ratio of 1:2:1, a hyperfine structure coupling of 22.4 G and g factor of 2.0049. Therefore, the spectrum was assigned to the methylene radical with two α protons on the same plane; this radical is formed by loss of a hydrogen atom from the acetoxymethyl group.In pyrolysing EVA films at 500°C, the yield of acetic acid from 10 Mrad‐150 g kg−1 film significantly decreased compared with that of unirradiated film, and it decreased with increasing crosslinking density.By measuring the IR spectra of methanolysed EVA films, the following results were obtained: the absorbances at 1740, 1250 and 1050cm−1, attributed to the CO, OCOR and COC groups, respectively, had a marked decrease, whereas the three peaks for 20Mrad film were much stronger than those of unirradiated film. On the basis of these findings, it is suggested that the crosslinking reaction in electron beam irradiated EVA film with lower doses takes place between the acetoxy groups and the main chains.
Rheological and mechanical behaviour of tetraglycidyldiaminodiphenylmethane (TGDDM)/anhydride epoxy systems
Authors: Corcuera M. A. , Andres M. A. , Sarasua R. , Mondragon I. 
Published: April 2007

AbstractThe curing of tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM) cured with hexahydrophthalic anhydride, tetrahydrophthalic anhydride and nadic methyl anhydride was studied using static rheological techniques under isothermal conditions in different temperature ranges for each system. 1:1 and 1:0.5 stoichiometric ratios were used in all three TGDDM/anhydride systems analysed. From the gelation times of each system at the different conditions employed activation energies were calculated. Flexural mechanical properties, such as elastic modulus, strength and strain to break, were also investigated for all the three TGDDM/anhydride systems employed for different anhydride weight contents which ranged from 0.5 to 1.34 parts of the anhydride weight corresponding to the stoichiometric composition. Possible reasons to explain the mechanical behaviour shown are discussed.
Anionic copolymers of octanelactam with laurolactam (nylon‐8/12)—IV. Dynamic thermomechanical and mechanical properties
Authors: Arvanitoyannis Ioannis , Kehayoglou Aristides H. , Blanshard John M. V. 
Published: April 2007

AbstractThe thermomechanical and the mechanical properties of a recent series of copolyamides of octanelactam (OL) and laurolactam (LL) (nylon‐8/nylon‐12) were studied. The glass transition temperature (Tg) and melting point (Tm) were determined with dynamic mechanical thermal analyser, and compared to those obtained with differential scanning calorimetry and the activation energy for glass transition was calculated. The copolyamides showed a minimum for tensile strength, yield stress, stress at 100% and modulus and a maximum for elongation at break at the composition 60/40 (OL/LL) which has the lowest crystallinity. Young's modulus against % elongation showed the classification of copolyamides in two groups (rich in OL or LL, respectively).
Miscibility of thermoplastic polyurethane elastomers with chlorine‐containing polymers
Authors: Ann Tae Oan , Han Kyeong Tae , Jeong Han Mo , Lee Sang Won 
Published: April 2007

AbstractThe miscibility behaviours of thermoplastic polyurethane elastomers (TPUs) with chlorine‐containing polymers were studied. Four kinds of TPUs containing 20, 40, 60 and 80wt% of poly(caprolactone) (PCL) diol as a soft segment were used for blending. Poly(vinylidene chloride‐co‐vinyl chloride) (P(VDC‐VC)) with a chlorine content of 70%, poly(vinyl chloride) (PVC) and chlorinated polyethylene (CPE) with a chlorine content of 40% were blended with TPUs to study miscibility. The results of optical clarity observation and thermal characterisation suggest that P(VDC‐VC) was miscible with all the TPUs investigated. PVC was only miscible with TPUs containing 40, 60, 80wt% PCL segment, whereas CPE was immiscible with all the TPUs studied. Tensile measurements showed that all the TPU with 60wt% of PCL segment/chlorine‐containing polymer blends were mechanically compatible.
Polymers based on N‐Aryl methacrylatoethyl carbamate
Authors: Santhana Krishnan P. Gopala , Choudhary Veena , Varma I. K. 
Published: April 2007

AbstractN‐Aryl methacrylatoethyl carbamate monomers were prepared by reacting phenyl isocyanate/4‐chlorophenyl‐isocyanate and 2‐hydroxyethyl methacrylat, Homopolymerisation and copolymerisation with methyl methacrylate in a tetrahydrofuran solution was carried out using azobisisobutyronitrile/benzoyl peroxide as an initiator at 60°C. Molecular characterisation of polymers was done by intrinsic viscosity determination at 30°C in chloroform and molecular weight determination by gas permeation chromatography using poly(methyl methacrylate) standards. Molecular weight distribution ranged from 1.5 to 2.63. Copolymer composition was determined by using 1H‐NMR. Thermal behaviour of the polymers in a nitrogen atmosphere was evaluated using dynamic thermo‐gravimetry.
The synthesis, characterisation and thermal behaviour of functionalised aryl cyanate ester monomers
Authors: Barton John M. , Hamerton Ian , Jones John R. 
Published: April 2007

AbstractThe syntheses of several functionalised aryl cyanate esters bearing reactive allyl groups are presented. The monomers were purified (to c. 98%) using preparative HPLC and a range of techniques, including heteronuclear nuclear magnetic resonance (NMR) spectroscopy, was employed in their characterisation. A model functionalised aryl cyanate ester was doped with a variety of additives and the resulting thermal behaviour examined using dynamic differential scanning calorimetry (DSC). Furthermore, the postulated co‐reaction of the model functionalised cyanate ester with bis‐maleimides was investigated using heteronuclear NMR and dynamic mechanical techniques.
Phase behavior of poly(ε‐caprolactone)/ poly (vinylidene fluoride) blends
Authors: Jo Won Ho , Park Soon Jong , Kwon Ick Hwan 
Published: April 2007

AbstractThe miscibility of blends of poly (ε‐caprolactone) (PCL)/poly(vinylidene fluoride) (PVDF) was studied by measuring the cloud point, melting point depression and crystallization kinetics. Lower critical solution temperature (LCST) behavior was observed at PCL‐rich compositions, whilst it was not observed at high compositions of PVDF. However it is possible that an LCST could exist below the melting point of PVDF. From analysis of the melting point depression, the Flory interaction parameter x12, was calculated from the Nishi‐Wang equation and the value was found to be‐1.5. The crystallization rate of PCL increased with increasing amount of PVDF in the blend. The spinodal curve for PCL/PVDF blends was simulated by using the lattice‐fluid theory.
Studies on the kinetics of photo‐initiated radical polymerisation of modified epoxy resin
Authors: Chandra R. , Thapliyal B. P. , Sehgal Babita , Soni R. K. 
Published: April 2007

AbstractThe diglycidyl ether of bisphenol‐A (DGEBPA) was modified by acrylic acid. The reaction between the active epoxy groups of DGEBPA and the carboxylic group of acrylic acid was catalysed by triphenyl phosphine to prepare di(vinyl‐2‐hydroxypropanoate) ether of bisphenol‐A (DEBA). The DEBA so formed was co‐polymerised with 2‐ethylhexylacrylate using benzophenone as the photo‐initiator to yield a flexible polymer. The kinetics of the photo‐initiated radical polymerisation was studied by a new technique called differential photo‐calorimetery and the results thus obtained were analysed to determine the Arrhenius activation energy and pre‐exponential factor.
Size exclusion chrormatographic studies on the urethane reaction in hydroxyl‐terminated polymers
Authors: Balagangadharan V. P. , Catherine Korah Bina , Kannan K. G. , Ninan K. N. 
Published: April 2007

AbstractSize exclusion chromatography (SEC) has been used to study the influence of molecular weight on the reactivity of the hydroxyl group in free radically polymerised hydroxyl‐terminated polybutadiene (HTPB). The HTPB prepolymer was converted into a UV‐absorbing urethane derivative by reaction with phenylisocyanate and the degree of conversion was followed from the UV/DRI (Differential Refractive Index) signal of the derivative using dual detector SEC. Though the overall reaction levelled off at about 70% conversion at room temperature, the time taken by different molecular weight species to attain this level was different. The computed rate constants were larger for the higher molecular weights in a given sample. This is attributed to the polyfunctionality of the higher molecular weight species.
Crystal structure, crystallization kinetics and morphology of a new polyimide
Authors: Cheng Stephen Z. D. , Mittleman Martin L. , Janimak James J. , Shen Dexing , Chalmers Tammy M. , Lien Hsun‐Shen , Tso Chung C. , Gabori Patricia A. , Harris Frank W. 
Published: April 2007

AbstractA new semicrystalline polyimide has been synthesized from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 2,2‐dimethyl‐1,3‐(4‐aminophenoxy)propane. The polymer has a high glass transition temperature of 230°C and a melting temperature of 325°C. Its overall crystallization rate between 240 and 325°C is quite fast (t1/2<10min) and relatively insensitive to the crystallization temperature. Although the degree of crystallinity obtained is dependent on the crystallization conditions, it can be as high as 50%. The polymer's morphology, which was examined with transmission electron microscopy (TEM), has a randomly stacked, ribbon‐like, lamellar texture. Both TEM and polarized light microscopy show that mature spherulites do not develop. The crystal unit cell, which was determined from wide‐angle X‐ray diffraction measurements on highly oriented films, is monoclinic with a = 0.960nm, b = 0.582nm, c = 2.46nm and γ = 81.1°.
Polymerization by phase transfer catalysis. 14. Polyesters from terephthalic acid and related diacids with bisphenol A
Authors: Tagle L. H. , Diaz F. R. , Roncero S. 
Published: April 2007

AbstractPolyesters were synthesized from the following acid dichlorides: terephthaloyl (I), p‐phenylenediacetyl (II), and p‐phenylenedi(oxyacetyl) (III) and bisphenol A as diphenol under phase transfer conditions. Quaternary ammonium and phosphonium salts were used as phase transfer catalysts in a 1,1,2,2‐tetrachloroethane/NaOH system. Polyesters were characterized by IR and 1H NMR spectroscopy, and elemental analysis. The influence of the catalysts and the reaction time were evaluated by the yields and ηinh values. The influence of the nature of the acid dichloride was higher than that of the catalysts due principally to the aliphatic character of the acid dichlorides II and III.
Polymerization by phase transfer catalysis. 15. Polyesters from tetrachloroterephthalic acid and related diacids with bisphenol A
Authors: Tagle L. H. , Diaz F. R. , De Fuente M. La 
Published: April 2007

AbstractChlorinated polyesters were synthesized from the following acid di‐chlorides: 2,3,5,6‐tetrachloro‐1,4‐terephthaloyl (I), 2,3,5,6‐tetrachloro‐1,4‐phenylenediacetyl (II), and 2,3,5,6‐tetrachloro‐1,4‐phenylenedi(oxyacetyl) (III), and bisphenol A, under phase transfer conditions, using several ammonium and phosphonium salts as catalysts and a biphasic CH2Cl2/NaOH system. The influence of the nature of the catalysts and the reaction times were evaluated by the yields and ηinh of the polyesters. The reactivity of the monomers was I<II<III, due to the smaller influence of the tetrachlorinated ring when there is a spacer group between the aromatic ring and the acid chloride group.
Semi‐interpenetrating polymer networks from castor oil‐based polyurethanes and chlorinated rubber
Authors: Parthiban S. , Rajalingam P. , Radhakrishnan Ganga 
Published: April 2007

AbstractSemi‐interpenetrating polymer networks (semi‐IPNs) were prepared by crosslinking castor oil in the presence of chlorinated rubber. Crosslinking in toluene solution was effected with 2,4‐toluene diisocyanate or hexamethylene diisocyanate at various NCO/OH ratios. The semi‐IPNs were obtained as tough films and were characterized by their mechanical, thermal, morphological and electrical properties.
Preparation and characterization of polymer stabilized polystyrene latex
Authors: Oun Ahmed Mohammed 
Published: April 2007

AbstractA polystyrene latex was prepared which was stabilized using the most effective stabilizer, i.e. a graft copolymer of polystyrene‐poly(ethylene oxide). The latex and the stabilizer were characterized using infrared, elemental analysis, viscometry, osmometry, electron microscopy and microelectrophoresis techniques. The results show that the polystyrene latex is sterically stabilized and could be used for thermodynamic and kinetic studies.
Abnormalities in electrical and acoustic properties of thermoplastic polyurethane
Authors: Volkova A. V. , Domkin A. N. , Strachov V. V. 
Published: April 2007

AbstractThe temperature dependence of ultrasonic pulse velocity C and specific volume resistance ρv of crystallizing thermoplastic polyurethane (TPUR) was investigated. It was revealed that under certain conditions TPUR acquired abnormally low ρv values and C values uncharacteristic of polymers. An explanation for the observed abnormalities could be based on the assumption of the presence of ‘hot’ electrons in TPUR.