bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of carbon surface functionality on tetrafunctional epoxy resin–diaminodiphenylsulfone cure reactions
Authors: Wang Shiping , Garton Andrew , Stevenson William T. K. 
Published: April 2003

AbstractAcidic functionality on the surface of oxidized carbon blacks modifies the cure processes of the tetrafunctional epoxy resin MY720 (largely tetraglycidyldiaminodiphenylmethane, TGDDM) crosslinked with diaminodiphenylsulfone (DDS). In the early stages of the cure (up to 60 min at 140°C), the rate of consumption of TGDDM and DDS and the rate of production of the 1 : 1 adduct are increased, together with an increase in the production of ether functionality. These chemical changes are associated with an increase in exotherm. an increase in gel fraction, and preferential adsorption of the amine curing agent on the carbon surface. During the middle stages of the cure (after 180 min at 140°C), the acidic carbon black has a slight retarding effect on the cure; but, on completion of the later stages of the cure, the effect of the carbon surface functionality diminishes, and, in contrast to earlier studies with difunctional epoxy resins, neither the total cure exotherm nor the final glass transition temperature is affected greatly. We attribute this difference to the greater ease of etherification reactions for the tetrafunctional resin compared to the difunctional case. Basic functionality on the surface of carbon black (induced by carbon dioxide treatment) has a slight retarding effect on TGDDM consumption in early stages of the cure. Less adsorption occurs on the basic carbon than on the acidic carbon, and the adsorbed material appears to be rich in resin. These results imply that treated carbon surfaces may advance or retard the local cure state of an MY720–DDS matrix, but will not affect markedly the final cure state.
Toughening of SMA copolymers with an SAN‐grafted rubber
Authors: Kim J. H. , Keskkula H. , Paul D. R. 
Published: April 2003

AbstractStyrene/maleic anhydride (SMA) copolymers were toughened by blending with a styrene/acrylonitrile (SAN) grafted rubber. The AN content of the SAN graft was fixed at 22.5% and the MA content of the SMA matrix was varied from 8 to 25%. The maximum impact strength was observed for blends based on SMA copolymers containing 14–17% MA (depending on the rubber content). These compositions are near the boundary of miscibility between the SMA matrix and SAN graft since miscibility of SMA and SAN occurs when the MA and AN contents are about the same in each Dilatational processes were shown to be the major mechanism of defor‐mation for these blends. Scanning electron microscopy was used to observe fracture surfaces as the miscibility between SMA and SAN or as the rubber content was changed. Toughening of miscible SMA/SAN matrices by this impact modifier was also examined. The results are discussed in terms of a variety of possible contributing factors including the coupling of the rubber to the matrix via miscibility of the latter with the SAN graft.
A study of some linear aliphatic nylons by thermally stimulated creep
Authors: Tang Henry H. Y. , Williams H. Leverne 
Published: April 2003

AbstractThe mechanical behavior of nylons 6,66,666,610,612,11 and 12 was studied using the method of thermally stimulated creep at 96°C. The resultant creep moduli were calculated. The strain recovery and strain recovery rates were measured and the retardation time spectra calculated as a function of temperature. The effects of humidity on the creep and subsequent recovery behavior were compared using samples conditioned to 0, 33, and 97% relative humidity at room temperature.
Two‐stage drawing of acetone treated poly(ethylene terephthalate) fibers
Authors: Ito Masayoshi , Miya Hisakazu , Watanabe Miho , Kanamoto Tetsuo 
Published: April 2003

AbstractAcetone‐treated fibers of poly(ethylene terephthalate) were drawn by a two‐stage drawing technique: cold‐drawing at 25°C followed by hot‐drawing at 230°C by tensile force. The maximum achievable draw ratios (TDRs) for the treated and the untreated original fibers were 11.5 and 9.5, respectively. The highest modulus and strength of 28 and 1.2 GPa, respectively, were obtained by drawing the treated fibers with the highest TDR. These values were about 20% higher than those for the untreated drawn fibers with the highest TDR. Although annealing of the untreated drawn fibers under tensions singificantly improved the tensile modulus up to the maximum modulus for the treated drawn fibers, the tensile strength of such annealed fibers decreased remarkably due to the degradation occurring during annealing. The crystallinity of the drawn sample from the treated fiber was higher than that from the untreated fiber, leading the former to a higher structural stability against heat than the latter. These results were explained by the existence of small and/or less perfect crystals in the treated fibers induced by acetone.
Polyamic acid interactions with aminopropylsilane surface conditioners on metal
Authors: Linde H. G. 
Published: April 2003

AbstractGrazing incidence infrared analysis reveals that metal surfaces of Ag, Al, Cu, Cr, and Al/Cu or Al/Cu/Si alloys interact with APS solutions of natural pH (10.4) to produce passivating siloxane films. These films restrict polyamic acid interaction with metal and amine functionalities, so that covalent attachment of the amic acid to the surface, through the adhesion promoter, does not occur. Instead, imidization appears to proceed in a normal fashion above a siloxane interfacial region which is coordinated to the metal surface by amine‐metal interactions.
Pervaporation separation of water/ethanol mixtures through polysaccharide membranes. V. The relationships between the permselectivity of chitosan salt membrane and its solid state structure
Authors: Mochizuki Akira , Amiya Shigetoshi , Sato Yoshio , Ogawara Hisashi , Yamashita Shuzo 
Published: April 2003

AbstractThe separation of water/alcohol mixtures through chitosan salt membranes was investigated. When neutralized by sulfuric acid, the separation factor increased to over 1000, but neutralized by hydrochloric acid, it was at most 50. The difference was mainly explained not only by the contraction of the “hole” due to the conformation change of chitosan molecule but also by the mobility of chitosan molecule which would correspond to the fluctuation of the “hole” size. The conformation change and the mobility of chitosan molecule were meaśured using CP/MAS 13C‐NMR. The spin–lattice relaxation time reflects the mobility of chitosan molecule. The results of the spin–lattice relaxation time obtained from NMR indicated that the mobility of chitosan sulfate was not affected much by the neutralization degree, but the mobility of the hydrochloride was markedly affected. The difference of the selectivity in these membranes could be explained by these results.
Surface‐modified polysulfone hollow fibers. II. Fibers having CH2CH2CH2SO3− segments and immersed in HCI solution
Authors: Higuchi Akon , Iwata Noboru , Nakagawa Tsutomu 
Published: April 2003

AbstractPolysulfone ultrafiltration hollow fibers were chemically modified on the surfaces with propane sultone and SnCI4, and immersed in HCI solution subsequently. The immersion of the fibers in HCI solution yielded lower molecular weight cutoff of the fibers than those without the immersion. The fiber, denoted as HP‐SB‐17H, rejected 5% of raffinose at feed concentration = 0.5 wt % and 14% of NaCI at the feed concentration = 0.0025 wt %. The rejection of NaCI for HP‐SB‐17H was found to increase with the decrease of the feed concentration, and showed the tendency of Donnan exclusion. The effective fixed charge density was estimated to be 7.74 × 10−4 eq/L for the fiber. Absorption of poly(ethylene glycol) and bovine serum albumin at pH 7.0 on nonmodified and modified fibers was estimated from the ratio of Jη/J0η0, where J is flux, η is viscosity, and the suffix zero shows the values of pure water. The modified fibers with the propane sultone showed better results of antiabsorption than the nonmodified and conventionally sulfonated fibers in this study. This was attributed to the high flexibility of a sulfonated group originating from the existence of a joint segment of (‐CH2‐)3 in the modified fibers.
Alumina fibers from poly[((3‐ethoxypropanoyl)oxy)aloxane]
Authors: Morita Hisao , Yamane Hideki , Kimura Yoshiharu , Kitao Toshio 
Published: April 2003

AbstractAlumina fibers were obtained from the poly[((3‐ethoxypropanoyl)oxy)aloxane] (P‐3EPA) by using a polymeric precursor technology. The rheological properties of the concentrated solution of P‐3EPA related to the extrusion and spinning processes have been investigated to determine the processability into fine filaments. Thirty weight percent P‐3EPA dissolved into toluene showed an excellent spinnability and fine filaments of 20–30 μm in diameter were easily obtained. The phase changes during the sintering of the fiber were studied with wide‐angle X‐ray diffraction and were shown to be strongly related to the mechanical properties of the fiber. Further the addition of the ethyl silicate (ES) as a sintering agent which prevent the crystal growth of Al2O3 was found to be effective to improve the mechanical properties of the alumina fiber.
Homogeneous radiopaque polymers with organobismuth compounds
Authors: Delaviz Yadollah , Zhang Zhao‐Xi , Cabasso Israel , Smid Johannes 
Published: April 2003

AbstractThe effectiveness of triphenylbismuth and a few other bismuth compounds for use as a radiopacifying (X‐ray contrast) additive in polymeric materials was tested. Ph3Bi was found to be compatible (sometimes up to 70 wt %) with a wide range of monomers and polymers. It yields homogeneous mixtures with polystyrene, poly(vinyl chloride), polyacrylates, polyethylene, and other polymers. They can be formed by solvent casting, by melt processing, or by polymerizing a Ph3Bi/monomer mixture. Polymerization is not affected by the presence of Ph3Bi even when amine accelerators are used. Radiopacities of the polymer mixtures are proportional to the molar content of Ph3Bi, and can easily exceed that of aluminum. The bismuth compound lowers the Tg of PVC, PMMA, and polystyrene by 1.3°C/wt % Ph3Bi. The additive is moisture‐insensitive, water‐insoluble, and heat‐stable. It does not leach into water and has a low toxicity index. Leaching even in organic solvents can be prevented entirely by covalently binding bismuth to the polymer matrix through the use of monomers such as styryldiphenyl bismuth.
Interpenetrating polymer networks based on castor oil, XVIII
Authors: Patel Prashant , Shah Tarulata , Suthar Bhikhu 
Published: April 2003

AbstractCastor oil—a renewable resource—is abundantly grown in tropical countries. It is a triglyceride of glycerol and ricinoleic acid containing hydroxyl functionality. These hydroxyls were reacted with 4,4′‐diphenyl methane diisocyanate to form prepolyurethanes with different NCO/OH ratios. The prepolyurethane was swollen in ethyl methacrylate monomer containing 1% ethylene glycol dimethacrylate as crosslinker by radical polymerization initiated with benzoyl peroxide. The polyurethane/poly(ethyl methacrylate) interpenetrating polymer networks (IPNs) PU/PEMA were obtained as tough films by casting into glass molds. These IPNs were characterized by their resistance to chemical reagents, optical properties (% transmittance), thermogravimetric analysis and mechanical properties, dynamic storage modulus (ϵ′), loss modulus (ϵ″), and loss tangent (tan δ) by dynamic mechanothermal analysis, morphology by scanning electron microscopy, and dielectric properties (σ, ϵ′, ϵ″ and tan δ) at different temperatures.
Degradation of polystyrene by shear stress in isopropylphenyl phosphate solution
Authors: Netopilík Miloš , Kubín Miroslav , Güntherschultz  , Vohlídal Jiří , Kössler Ivo , KratochvíL Pavel 
Published: April 2003

AbstractThe molecular weight distribution functions of polystyrene degraded by shear stress in isopropylphenyl phosphate solution were compared with the calculated ones, obtained by assuming that up to a certain distance from each chain end the probability of bond scission is zero. Two phenomenological models were proposed for the probability of degradation in the central part of the chain. A comparison with experimental data suggests that the probability of degradation increases towards the center of the chain. Branched fractions formed by degradation in the presence of air were found to be present by the GPC method with on‐line viscometric detection.
Synthesis and properties of multiblock copolymers based on polyoxyethylene and polyamides by diisocyanate method
Authors: Otsuki Toshihiro , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractPolyoxyethylene–polyamide multiblock copolymers were successfully synthesized from α, ω‐polyoxyethylene–dicarboxylic acid (POE–diacid), a mixture of two dicarbroxylic acids, and an aromatic discocynate by two synthetic routes, i.e., one‐step and two‐step method. In the two‐step method, α, ω‐diisocyanate‐terminated polyamide oligomers, preformed from a mixture of isophthalic acid (IPA) and azelaic acid (AZA) with 4,4′‐methylenedi (phenyl isocyanate) (MDI), were reacted with POE–diacid to form multiblock copolymers. In the one‐step method, the reaction components, MDI, IPA, AZA, and POE diacid, were reacted all together. These polymerizations were carried out in the presence of 3‐methyl‐1phenyl‐2‐phospholene 1‐oxide as a catalyst in tetramethylene sulfone, giving multiblock copolymers with inherent viscosities of 0.5–1.1 dL/g. They were soluble in amide‐type solvents, and transparent, ductile, and elastomeric films could be cast from their N,N‐dimethylacetamide solutions. The tensile strength and modulus of the films thus prepared decreased with an increase in the polyoxyethylene content, whereas the elongation at break increased. The tensile strength/elongation at break/tensile modulus of the multiblock copolymer films ranged from 47 MPa/160%/1.1 GPa to 15 MPa/880%/12 MPa.
The second‐generation polysulfone gas‐separation membrane. I. The use of lewis acid: Base complexes as transient templates to increase free volume
Authors: Kesting R. E. , Fritzsche A. K. , Murphy M. K. , Cruse C. A. , Handermann A. C. , Malon R. F. , Moore M. D. 
Published: April 2003

AbstractThe second‐generation polysulfone (PSU) gas‐separation membrane is seen as a trilayer that is considerably more permeable and at least as selective as the first‐generation bilayer that it has replaced. In air separation, a fourfold increase in oxygen permeabiliy has been obtained with no loss in oxygen/nitrogen selectivity. The enhanced performance is the result of a membrane skin that is not only thinner, but also exhibits increased free volume and a graded density. The key to the emergency of the trilayer morphology was the discovery of a hitherto unsuspected relationship between the size of solvent molecules within a sol and the free volume and permeability in the resultant gel! Solvent molecules with a molar volume V > ˜ 147 cc/mol function as transient templates (spacers) that decrease macromolecular packing density. As a practical matter, the low diffusivity (difficult extractibility) of large solvent molecules is circumvented by the use of 1:1 Lewis acid: base (A:B) complexes such as propionic acid: N‐methyl pyrrolidone instead of neat solvents. Complexes whose acid and base strengths, respectively, lie between (Gutmann 47 < AN < 53 and 27 < DN < 28) are sufficiently stable to function as templates, while at the same time exhibiting the hydrolytic instability that leads to their ready disassociation and extraction by water. Selectivity is maintained by the use of A:B complexes whose Hildebrand solubility parameters differ from that of PSU by less than ˜ 1.3 (cal/cc)½. The emergence of the trilayer membrane is considered to be the second decoupling of permeability from selectivity. By the formation of an anisotropic (graded density) skin, permeability has been increased and selectivity maintained. This is analogous to the first decoupling by Loeb and Sourirajan who essentially replaced a thick dense monolayer film with a bilayer consisting of a thin skin of uniform density in series with a thick porous substructure.
Phosphoric acid cation exchange resins from chemically modified polyvinyl chloride
Authors: Biswas Mukul , Moitra Subrata 
Published: April 2003

AbstractPVC modified by Cl displacement reaction with meta‐aminophenol (MAP), bisphenol A (BISA), and phenolphthalein (PHEN) has been converted into phosphoric acid cation exchange resins. These resins have been characterized in regard to their structure, ion exchange properties, and thermal stability. The ion exchange capacities fall into the range 5.5–8.0 (meq/g) for the resins. The overall thermal stability is considerably higher than that for the corresponding sulfonic acid resins, as well as for the PVC–MAP, PVC–BIS A, and PVC–PHEN condensates. The resins exhibit ca. 4–6% capacity losses under isothermal hydrolytic cleavage at 100°C for 24 h.
The structure of Bombyx mori silk fibroin membrane swollen by water studied with ESR, 13C‐NMR, and FT‐IR spectroscopies
Authors: Yoshimizu Hiroaki , Asakura* Tetsuo 
Published: April 2003

AbstractStructure of Bombyx mori silk fibroin membrane insolubilized with methanol, especially in the swollen state, is studied by means of spin‐label ESR, 13C‐NMR, and FT‐IR (ATR method) spectroscopies. FT‐IR data indicate that the conformational transition from random coil to antiparallel β‐sheet occurs at the surface of the membrane upon immersion into 80% aqueous methanol. High resolution 13C‐NMR observation of the membrane swollen in water shows that, the random coil portion whose segmental motion is very fast remains in the inner part of the swollen membrane. The fraction of this portion decreases with increasing methanol treatment time in the sample preparation. The heterogeneous structure of the swollen membrane was clarified from the complicated ESR spectra of the spin‐labeled silk fibroin membranes. The ESR spectra were analyzed quantitatively and the fractions of the fast, slow, and very slow motions of the spin‐label site (tyrosine side chain) were determined. A model is proposed for the heterogeneous structure of the swollen silk fibroin membrane.
Wool butadiene copolymers. I. Preparation and morphology
Authors: Russell Ian M. , Evans David J. 
Published: April 2003

AbstractWool may be readily grafted with poly(butadiene) by gamma‐ray mutual irradiation or solutionfree radical techniques. Some factors important in the preparation are discussed. Through microscopic and chemical analyses, the radiation‐grafted polymer has been shown to be largely associated with, and bound to, the high‐sulfur matrix regions of the wool fiber, although there is some specific deposition in the outer exocuticle and in the normally inert regions of the cell membrane complex. The radiation grafted poly(butadiene) isolated by removal of the wool protein by acid hydrolysis has a crosslinked structure typical of other polybutadienes prepared by radiation‐induced polymerization. As the grafting yield increased, the molecular weight between points of grafting to the wool increased.
Permeability through cellulose membranes grafted with vinyl monomers in a homogeneous system. VI. States of water in membranes swollen in solutions
Authors: Nishioka Noboru , Yamaguchi Hideki , Kosai Kouichi 
Published: April 2003

AbstractCellulose grafted with vinyl monomers in a dimethyl sulfoxide–paraformaldehyde solvent system was used as membrane materials. The states of water in the membranes swollen in aqueous solutions of NaCl, raffinose, and poly(ethylene glycol) (PEG) were investigated. The amounts of total water and freezing water for the solution‐swollen membranes hardly depended on the kind of solutions and were similar to those for the water‐swollen membranes. The free water contents for the solution‐swollen membranes were different from those for the water‐swollen membranes. Apparent activation energies for diffusive permeation of solutes through the membranes were measured. A poor permeability of PEG through the membranes was consistent with a large activation energy for permeation of PEG through them.
Immobilized extractants: Selective transport of magnesium and calcium from a mixed chloride solution via a hollow fiber module
Authors: Belfer S. , Binman S. , Lati Y. , Zolotov S. 
Published: April 2003

AbstractA supported liquid membrane process was used for the selective transport of alkali earth cations from solutions containing a mixture of alkali and alkali earth chlorides. Bis‐trimethylpentylphosphinic acid (HDTMPP), an organophosphorous acid, was used as the carrier in the liquid membrane supported by a polypropylene fiber. It was found that the porous structure of polypropylene fiber suffered significant irreversible changes due to the formation of an inorganic salt of HDTMPP. This caused a reduction in the cation fluxes and the final failure of the supported liquid membrane.
Water solubility characteristics of some ion‐containing acrylic copolymers
Authors: Hurley Steven M. , Stackman Robert W. , Orler E. Bruce 
Published: April 2003

AbstractThe water solubility characteristics of a series of ionic copolymers of acrylic acid with acrylic esters was determined. A relationship was developed between solubility and the ionic character of the copolymers. In addition to water solubility, the effects of the composition and degree of neutralization upon other copolymer properties were also examined. Moisture effects upon the physical properties can be minimized by limiting the ionic character of the copolymer to that required for water solubility. The effects of molecular weight on the solubility and speed of dissolution was also investigated and found to have no effect, within the range of composition of the copolymers investigated.
Adsorption of a functionalized polymer from dilute nonaqueous solutions by silica
Authors: Ayub A. Latiff , Ling Samson S. M. 
Published: April 2003

AbstractThe adsorption of a functionalized styrene–butadiene (SB) diblock copolymer from toluene solutions at 25°C onto silica of varying particle sizes was studied using thermogravimetric analysis. The copolymer was chemically modified by hydroformylation, and the adsorbate concentration ranged from 0 to 2% by weight. The modified copolymer was adsorbed by the silica particles, but the unmodified copolymer was not. The plateau adsorption was found to increase with silica surface area, and the level of surface coverage ranged from 0.4 to 0.8 mg/m2.
Chemorheology of an epoxy resin system under isothermal curing
Authors: Hou T. H. , Huang Joan Y. Z. , Hinkley J. A. 
Published: April 2003

AbstractThe chemorheological properties of a commercial Hercules 3501‐6 resin system were studied under isothermal curing conditions between 375 and 435 K. For cure temperatures ≥ 385 K, the storage modulus curing curves, G′(t), exhibited abrupt changes in slope which occurred at various times depending on the curing temperatures. These slope changes were attributed to the onset of gelation. Crossover points between G′(t) and G″(t) curves were observed for curing temperatures ≥ 400 K. The gelation and the crossover points obtained from the chemorheological measurements, therefore, defined two characteristic resin states during cure. Although gelation theory did not predict them correctly, the degree of cure in each of these states was approximately the same for every cure temperature. The temperature dependency of the viscosities in the characteristic resin states, and the rate constants of increase in moduli at different stages of curing were analyzed. Various G′(t) and G″(t) isothermal curing curves were also shown to be capable of being superimposed to one another by the principle of time‐temperature superposition. The resultant shift factors at(T) and aη(T) were shown to follow Arrhenius type relationships. Values of the activation energy suggested that the reaction kinetics, instead of the diffusion mechanism, was the limiting step in the overall resin advancement for cure at temperatures ≥ 385 K.