bluuebunny/crossref_metadata_2025 huggingface dataset:
Homogeneous radiopaque polymers with organobismuth compounds
Authors: Delaviz Yadollah , Zhang Zhao‐Xi , Cabasso Israel , Smid Johannes
Published: April 2003

The 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

Castor 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

The 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

Polyoxyethylene–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

The 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

PVC 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

Structure 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

Wool 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

Cellulose 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

A 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

The 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

The 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

The 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.
Synthesis, characterization, and properties of photosensitive silicon‐containing copolyimides
Authors: Lee Yu‐Der , Lu Chi‐Chi , Lee Hurng‐Rern
Published: April 2003

Copolyimides with siloxane moieties in the main chain were synthesized by solution polycondensation of 1,3‐bis(3‐aminopropyl) tetramethyldisiloxane (APMS), oxydianiline (ODA) with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) in N‐methyl‐2‐pyrrolidone (NMP). The adhesion properties between copolyimides and silicon wafer were improved significantly with incorporation of siloxane moiety into polymer chain.

Photosensitive copolyimide precursor was obtained by further reaction of silicon‐containing copolyamic acid with 2‐isocyanatoethyl methacrylate (IEM). The insoluble fraction of photosensitive copolyimide precursor reached 90% after 10 min of irradiation with UV light. In comparison, the thermal imidization of irradiated photosensitive copolyimide precursor was more difficult than that of silicon‐containing copolyamic acid. A longer heating time or higher imidization temperature was required.
Durable and hydrophobic surface modification by plasma polymers deposited from acetylene/hexafluoroacetone ethylene/hexafluoroacetone, and ethane/hexafluoroacetone mixtures
Authors: Inagaki N. , Tasaka S. , Takami Y.
Published: April 2003

Plasma polymerization of mixtures of ethane/hexafluoroacetone (HFA), ethylene/HFA, and acetylene/HFA deposit hydrophobic and thin films. The IR and XPS measurements of the deposited films show that fluorination with HFA occur to yield hydrophobic plasma films which possess CF3, CF2, and CF moieties. The advancing contact angle of water on the surface of the deposited films increases with increasing the HFA concentration, especially plasma polymer films prepared from the acetylene/HFA mixture (87.5 mol % HFA) show an advancing contact angle of 126 degrees. Such high hydrophobicity of the plasma polymer surface is attributed to high concentration of fluorinated carbons, especially CF3 side groups. The CF3 concentration in the plasma polymers reach about 30 mol % of the total carbon units. These surfaces show no change in advancing contact angle even when stored in a moist atmosphere of 60% RH at 20°C for at least 2 weeks.
Electroconducting polyaniline composite films prepared by chemical oxidative polymerization at gas/liquid interface
Authors: Morita Mitsuyuki , Hashida Isao
Published: April 2003

Electroconducting polyaniline composite films have been prepared by chemical oxidative polymerization at gas/liquid interface between heated aniline vapor and aqueous liquid membrane containing a water‐soluble matrix polymer and an oxidizing agent (and proton acid). The formed composite films are green, semitransparent and uniform. Conductivity, transmittance, and visible and IR spectra are investigated with the films prepared under various preparative conditions: aniline vapor exposure time, atmospheric and aniline temperatures, chemical species and concentration of the oxidizing agent, and concentration ratio of the proton acid to the oxidizing agent. The conducting composite films are formed with the liquid membrane containing above 680 mV of oxidation potential and some proton donor. The film conductivity is determined by the absolute amount of the radical cation structure component of polyaniline and the composition ratio of the radical cation component to the quinonediimine component of polyaniline, which is due to the oxidation potential and protonation effect of the liquid membrane. The excess proton acid coexisting with the oxidizing agent contributes to the film transmittance by uniform distribution of polyaniline in the composite film, aside from its contribution to conductivity by increase of the radical cation component at suitable concentration of the oxidizing agent.
High‐pressure FTIR studies of gas–polymer interactions
Authors: Fried J. R. , Li W.
Published: April 2003

FTIR spectra of cellulose acetate (CA) and poly(methyl methacrylate) (PMMA) at 35°C have been obtained as a function of carbon dioxide pressure at pressures up to 55 atm in a specially designed FTIR cell. Results indicate that the carbonyl stretching vibrations for CA (1752 cm−1) and PMMA (1731 cm−1) shift to slightly higher wave numbers with increasing pressure. The small shifts suggest dipole–dipole interactions between CO2 and the carbonyl group. In both cases, the shift appears to be linear with pressure. This linearity is interpreted in the framework of the dualmode theory to suggest that gas–polymer interactions occur in the Henry's law dissolution mode.
Environmental effects on latex paint coatings. II. CP/MAS 13C‐NMR and XPS investigations of structural changes in the base polymer
Authors: Sankar S. S. , Patil D. , Schadt R. , Fornes R. E. , Gilbert R. D.
Published: April 2003

Films of a base polymer, primarily a terpolymer of n‐butyl acrylate, vinyl acetate, and vinyl chloride, that is used in latex paint, have been exposed to various combinations of UV/air, UV/SO2, and UV/SO2/H2O. Reported here are results of elemental analyses, XPS and 13C magic angle spinning NMR of the exposed samples. When samples are exposed to UV/SO2 or UV/SO2/H2O, there is clear evidence of the incorporation of sulfur into the polymer, and there is significant loss of the acetate group in the copolymer. There is also evidence of the formation of unsaturated carbon–carbon bonds which is due to loss of the acetate groups and some dehydrohalogenation. During the time scale of exposures, changes in the composition and structure of samples exposed to UV/air were not detected by the techniques considered here although some chain scission and crosslinking undoubtedly occur. The results suggest a synergistic interaction between SO2 and UV leading to rapid degradation of the polymer, and that the presence of atmospheric SO2 pollutants can have an adverse effect on the lifetime of latex coating materials.
Cure kinetics of an epoxy‐novolac molding compound
Authors: Hsieh T. H. , Su A. C.
Published: April 2003

The cure reaction of an epoxy‐novolac molding compound was studied by means of differential scanning calorimetry using the dynamic (i.e., temperature scanning) approach. Based on a modified version of Friedman's method, a procedure aiming at the phenomenological description of cure kinetics was developed. This method was found capable of following satisfactorily the thermokinetics of the molding compound. Our results indicate that the cure reaction is autocatalytic in nature and does not follow simple nth‐order kinetics.
Basic functionalization of molten linear low‐density polyethylene with 2‐(dimethylamino)ethyl methacrylate in an intermeshing corotating twin‐screw extruder
Authors: Song Zhiquiang , Baker Warren E.
Published: April 2003

Functionalization of molten linear low‐density polyethylene (LLDPE) with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) was studied in an intermeshing co‐rotating twin‐screw extruder using a peroxide initiator. The influence of monomer concentration, initiator concentration, reaction temperature, the screw speed, and the mean reaction residence time on the grafting reaction was investigated in order to determine the reaction conditions necessary to obtain a controlled degree of grafting, DG, while minimizing homopolymerization and crosslinking. Relatively high grafting levels can be obtained without excessive polyethylene crosslinking by using high monomer concentrations, wm, with low initiator concentrations, wI. DG increased with increasing monomer concentration when wm exceeded a certain value. Processing temperatures between 130 and 160°C are optimal to achieve high grafting efficiency, GE. Too high a processing temperature resulted in both low DG and GE. An optimal reaction residence time of about 5 min was found for wm = 23 wt % and wI = 0.56 wt % to obtain relatively high DG and GE. The melt flow index of the reaction product, MFI, increased with increasing wm at constant wI. This suggests that the DMAEMA monomer has the ability to suppress crosslinking of the LLDPE chains. The ability of the DMAEMA monomer to compete for initiator and polymer radicals and reduce LLDPE crosslinking was further demonstrated by the study of sequential addition of monomer and initiator along the extruder. The competition among the three reactions (i.e., the desired grafting, homopolymerization, and crosslinking) is discussed.
Acoustic and viscometric studies of solutions of polystyrene and high‐impact polystyrene in benzene, toluene, and tetrahydrofuran
Authors: Al‐Jarrah Mustafa M. F. , Al‐Dujaili Amar H. , Hassun Subhi K.
Published: April 2003

Ultrasonic measurements of Polystyrene (PS) and high‐impact polystyrene (HIPS) solutions in benzene, toluene, and tetrahydrofuran are reported at 2‐MHz frequency. Effect of solvent and the rubbery phase of HIPS on the ultrasonic measurements are discussed. Observed relaxation times demonstrate the interaction of polymer–polymer macromolecules and polymer–solvent molecules. Results show a linear increase of velocity, density, viscosity, absorption coefficient, relaxation time, and relaxation amplitude values with increase of PS and HIPS concentrations. In contrast as a result of interaction between polymer molecules and solvent molecules compressibility decreased with increasing polymer concentration.
Blends of polyamide 6 with bisphenol‐A polycarbonate. II. Morphology–mechanical properties relationships
Authors: Gattiglia E. , Turturro A. , Pedemonte E. , Dondero G.
Published: April 2003

The relationships between morphology and mechanical properties in polyamide 6/bisphenol‐A polycarbonate blends have been investigated by means of Scanning Electron Microscopy and tensile tests. The immiscibility of the two polymers gives rise to biphasic blends in which the polycarbonate constitutes the matrix when its concentration is higher than 35 wt %. The morphology of the blends is controlled by the thermal and rheological characteristics, as well as by the mixing conditions. In general, the adhesion at the interface between the phases is absent. Moreover, polycarbonate‐rich blends can be considered as polycarbonate matrix with holes. As a consequence, the blends are mechanically much weaker than the pure components both in terms of Young's modulus and strength, at break. Blends very rich in polyamide, more than 90% by weight, behave differently, probably because of chemical, interchain interactions. This is reflected positively in the impact behavior, which was improved in this composition range.
Effective immobilization of protein linked with polyethylene glycol on silica via hydrogels using silica sol
Authors: Yoshinaga Kohji , Kito Taketoshi , Yamaye Makoto
Published: April 2003

An effective attachment of activated polyethylene glycol (PEG), which has dichloro‐s‐triazinyl functional groups, to silica and protein immobilization with the resulting PEG/SiO2 composite were studied. The reaction of methanol—silica sol with the PEG—silyl reagent resulted in an efficient PEG attachment to SiO2 as compared with the usual two‐step PEG modification of silica gel and glass surface. The activated PEG/SiO2 was able to immobilize over 600 mg of bovine serum albumin per unit gram of the PEG composite through hydrogel formation. The application of the present binding method of PEG‐linked protein on SiO2 was also discussed.
Viscoelastic behavior of concentrated oil solutions of sulfonated polymers. V. Effect of metal stearate plasticizers
Authors: Agarwal P. K. , Peiffer D. G. , Garner R. T. , Lundberg R. D.
Published: April 2003

Linear viscoelastic studies of concentrated blend solutions of metal neutralized sulfonated elastomers and low molecular weight metal stearate plasticizers are presented. The data of the magnesium and zinc salts of sulfonated EPDM polymer solutions in 100 N oil solvent as a function of magnesium and zinc stearate polar plasticizers show that addition of the latter species into the ionomeric elastomer solutions enhances their low temperature relaxation spectrum. The changes in properties are directly related to the enhancement of ionic interactions and filler effects of the plasticizers. At high temperatures, the zinc stearate molecules behave more as a conventional plasticizer. For ionomeric associating polymers, the phenomenon appears to be quite general in nature. The enhancement in properties is found to be a function of the counterion structure on the ionomer and stearate. In the case of these solution blends, the studies confirm that an ion‐exchange process can occur, especially at high temperatures, resulting in the counterion on the stearate moieties “exchanging” ionic sites on the ionomer. Apparently, this process proceeds quite slowly at low temperatures. However, it is clear from these measurements that the incorporation of metal stearates into the ionomeric solution changes the network structure at both low and high temperatures.
Grafting onto preformed polyester network using thermolabile azo groups
Authors: Erciyes A. Tuncer , Avci Ilknur , Yagci Yusuf
Published: April 2003

Polycondensation of 4,4‐azo‐bis(cyanopentanoyl chloride) and o‐phthalyl chloride between polyethylene glycol with addition of glycerine leads to polyester networks containing thermolabile azo groups. The networks have been characterized in terms of their swelling in benzene, chlorobenzene, and methacrylonitrile. Grafting of methacrylonitrile onto these preformed networks was then achieved by thermal decomposition of NN groups in the presence of methacrylonitrile.
Free volume theory for rheological properties of polymer blends
Authors: Steller Ryszard , Żuchowska Danuta
Published: April 2003

Theoretical model representing rheological properties of multicomponent blends as functions of their composition and properties of individual components was proposed. Applicability of this model was experimentally verified for two binary blends. In both cases a good agreement of theoretical predictions with experimental data was stated.
Physical and chemical aspects of glow discharge reaction on synthetic fibers
Authors: Mitchenko Yu. I. , Fenin V. A. , Chegolya A. S.
Published: April 2003

Polyethylene terephthalate (PET), polypropylene (PP), polyamide fibres, and films have been discharge treated. The resulting surface modifications analysed via ESR, IR, UV contact angle measurements. Discharge treatment introduces radicals and OH groups into the surface. But it does not correlate with wetability. Discharge treatment also produces the changes in conformation of macromolecules and roughness. This process is largely responsible for the wetability.
New epoxy compounds derived from substituted maleamic acids
Authors: Mikroyannidis John A.
Published: April 2003

Eight new epoxy compounds bearing maleamic acid moieties were prepared starting from 4‐(2,3‐epoxypropoxy)benzaldehyde (EPB) or 2,3‐epoxypropylglyoxylate monohydrate (EPG). The monomaleamic acid derived from an aromatic diamine (1,4‐phenylenediamine, 4‐aminophenyl ether, 4,4′‐diaminodiphenylmethane or 4,4′‐diaminodiphenylsulfone) reacted with EPB or EPG to afford the epoxy compounds. They were characterized by IR and 1H‐NMR spectroscopy. Their DTA traces showed that thermal polymerization started at 187–211°C. Network systems were obtained by crosslinking from the reaction of epoxy group with the maleamic carboxyl and through the olefinic bond. The TGA thermograms of crosslinked polymers showed that they were stable up to 275–295°C in N2 or air and afforded anaerobic char yield of 47–65% at 800°C. In addition, isothermal gravimetric analysis (IGA) was used to evaluate the thermo‐oxidative stability of a typical cured resin.
The four tiers of structure in integrally skinned phase inversion membranes and their relevance to the various separation regimes
Authors: Kesting R. E.
Published: April 2003

There are four superimposed tiers of structure in integrally skinned phase inversion membranes: macromolecules (functionally submacromolecules, that is, displacements between chain segments); nodules–approximately 200 Å in diameter spherical macromolecular aggregates, each of which contains several tens of macromolecules (nodule interiors are denser than interstitial regimes, therefore, chain segment displacements within and between nodules differ and hence constitute a bimodal pore size distribution which may account for the dual mode sorption and permeation of gases; transport of water in reverse osmosis occurs primarily through the less dense interstitial domains); nodule aggregates—400–1000 Å in diameter spherical clumps of nodules (the skins of reverse osmosis and gas separation membranes consist of a single layer of coalesced nodule aggregates; ultrafiltration pores are the spaces between incompletely coalesced nodule aggregates, and residual ultrafiltration pores are the defect pores found in reverse osmosis membrances); supernodular aggregates–aggregates of nodule aggregates which constitute the walls of the 0.1–2 μm in diameter open cells in the membrance substructure (microfiltration pores are the surface extensions of openings between adjacent cell walls).
Protease immobilization onto copoly(ethylene/acrylic acid) fiber
Authors: Emi Shingo , Murase Yasuhiro , Hayashi Toshio , Nakajima Akio
Published: April 2003

Water‐insoluble proteases were prepared by immobilizing papain and chymotrypsin onto the surface of the copoly(ethylene/acrylic acid) fiber. The effect of the surface area of the copolymer fiber on the amount of the immobilized protease was investigated. The mode of the immobilization between protease and copolymer such as a covalent fixation or an ionic interaction on the enzymatic activity and the stability of the immobilized protease was also investigated. The stability of the immobilized protease was also investigated. The stability of the immobilized protease in this study meant thermal stability, durability for repeated use, stability in urea, and durability for repeated washing. The activity of covalently immobilized proteases was found to be still higher toward small ester substrates, but rather low toward casein, a high molecular weight substrate. The covalently immobilized proteases onto the copolymer fiber gave an almost constant specific activity, suggesting less structural deformation of the protease molecule than the conventional immobilized enzyme system in the lower surface concentration. The thermal stability of the immobilized proteases was higher than that of the respective ionic interaction or native proteases. The initial enzymatic activity of the covalently immobilized proteases was maintained almost unchanged without any elimination and inactivation of proteases when the batch enzyme reaction was performed repeatedly, indicating excellent durability.
General procedures to determine the composition of commercial, two‐part polysulfide aircraft sealants
Authors: Ennis Brian C. , Hanhela Peter J. , Huang Robert H. E. , Long Geoffrey J. , Paul D. Brenton
Published: April 2003

Interpretation of the chemical processes which polysulfide sealants undergo either on storage or when the cured material is subjected to environmental influences requires detailed knowledge of formulations. Procedures have been developed to isolate and identify a range of additives in two‐part commercial aircraft sealants of both the dichromate and manganese dioxide cure types. Solvents, curing agent dispersants, and cure rate modifiers were separated chemically and thermal analysis was demonstrated to provide a ready means to estimate carbon in fillers. The phenolic resin adhesion enhancers were conveniently determined using 13C‐NMR spectroscopy and could also be identified using size exclusion chromatography. It was shown that virtually no interaction occurred between polysulfide liquid polymers and phenolic resins following aging at 70°C for 7 days. The most appropriate methods for determining curative levels were established and new means of assessing thiol content of the polysulfides by both 13C‐NMR and PMR spectroscopy are described. The significance of aspects of the sealant formulations is discussed.
Interpenetrating polymer networks of cellulose nitrate and castor oil based polyurethanes—development and characterization
Authors: Natchimuthu N. , Rajalingam P. , Radhakrishnan Ganga , Francis D. Joseph
Published: April 2003

Semi‐interpenetrating polymer networks of cellulose nitrate and castor oil based polyurethanes have been prepared by using excess diisocyanate for the crosslinking process. Semi‐IPNs with 30% cellulose nitrate showed some degree of miscibility. Enhanced miscibility was observed by the partial replacement of cellulose nitrate with poly(vinyl chloride‐co‐vinyl acetate). The ternary IPNs of poly(vinyl chloride‐co‐vinyl acetate), cellulose nitrate, and polyurethanes showed increased tensile strength and decreased flammability than those based on cellulose nitrate and polyurethanes alone.
Photodegradation of ethylene–propylene copolymer and ethylene–propylene–ethylidenenorbornene terpolymer
Authors: Maecker Norbert L. , Priddy Duane B.
Published: April 2003

Significant progress has been made in recent years regarding the photooxidation of olefin copolymers, but questions still remain. This paper reviews the progress and probes the photooxidative chemistry of ethylene–propylene (EP) and ethylene/propylene/diene monomer (EPDM) copolymers. Both stabilized and unstabilized polymer plaques were irradiated in a xenon are and the surface chemistry followed using infra‐red spectroscopy. Model compounds were used to help elucidate the chemistry caused by unique structural features present in the copolymers. Volatile products evolved during photooxidation were determined giving valuable insight into the degradation chemistry.
Cooperation between chemical and physical networks in crosslinked and plasticized PVC
Authors: Hjertberg Thomas , Dahl Roger
Published: April 2003

The effect of crosslinking of plasticized PVC on the mechanical properties has been investigated. Crosslinking was performed by using a dithioltriazine, and penetration as a function of temperature was used to follow the changes in mechanical properties. Changes in the melting behavior were detected by differential scanning calorimetry. Even rather low levels of gel content gave a substantial reduction in penetration in the interval 60–110°C, while a more complete reaction prevented major penetration up to at least 200°C. The penetration curve of heavily crosslinked materials showed several plateaus and the transitions could be related to melting of different crystallites formed by annealing at different temperatures. The physical network formed by the crystallites constitutes an important complement to the chemical network in plasticized PVC crosslinked by dithioltriazine. Both the amount and the melting temperature of the crystallites increased after annealing. The introduction of the chemical network further improved the heat resistance of the crystallites. The presence of the two networks will therefore show a synergistic effect with respect to the mechanical properties at increased temperatures.
Mechanical relaxations of nylon–polyurea block copolymers
Authors: Gardlund Zack G.
Published: April 2003

Dynamic mechanical analysis from −150 to +150°C has been carried out on seven block copolymers that were prepared by the in situ anionic polymerization of caprolactam in the presence of a preformed polyurea. The various relaxations have been identified and activation energies calculated. Some polymer–polymer miscibility of the polyurea and amorphous nylon copolymer segments is indicated by the compositional dependence of the α relaxation.
Studies on the mechanism of draw resonance in melt spinning
Authors: Jinan Cao
Published: April 2003

The physical mechanism of draw resonance of polymer fluids in melt spinning has been studied. It is proposed, according to the cross‐sectional area dependence of the local draw ratio of the filament along the spinline, that filament drawing can be divided into three modes which are given in the main text. In particular, it is found that the nonuniformizing draw mode is the necessary condition of draw resonance. The mechanism is certified through the analytical solution of isothermal melt spinning under uniform spinning stress and the critical draw ratio of isothermal and uniform tension melt spinning. The mechanism was employed to analyze the promotive and suppressive factors of draw resonance in a real spinning system and the development of filament unevenness along the spinline.
Orientation development in retensilized, biaxially oriented polypropylene films
Authors: Strobel Joan M. , Nam Sehyun
Published: April 2003

A basic study of orientation development in retensilized, biaxially oriented polypropylene films was performed. Wide‐angle X‐ray scattering (WAXS) and birefringence measurement techniques were used to examine films prepared under specific processing conditions. Biaxial orientation factors were determined for these films and were correlated with end‐use properties of the materials. In particular, the dispensability of oriented polypropylene films was found to correlate with crystalline‐phase and amorphous‐phase orientation factors. Dispensability is a relatively important property of pressure‐sensitive tapes; it is defined as the force necessary to cut a film backing over a serrated blade of the type used in commercially available adhesive‐tape dispensers.
Hydrosilylation crosslinking of silicone rubber catalyzed by bis (1,5‐cyclooctadiene) di‐μ,μ′‐chlorodirhodium
Authors: Heidingsfeldová Marta , Schätz Miroslav , Czakoová Marie , C̆apka Martin
Published: April 2003

Hydrosilylation vulcanization of addition silicone rubber catalyzed by bis (1,5‐cyclooctadiene) di‐μ,μ′‐chlorodirhodium at 150° was studied. The course of vulcanization, rubber network density, and mechanical properties of the vulcanizate are discussed with respect to the structure and molecular weight of the reactive groups of telechelic and internal vinylmethylpolysiloxanes and crosslinking methyl (hydrogen) dimethyl siloxane copolymers. Molecular weights of the polysiloxane components as well as the ration of unsaturated and Si—H groups were optimized. The results are in agreement with the theory of rubber elasticity of polymer networks and show wide application possibilities of the catalyst used.
Ionomers made from terpolymers with uniform poly(methyl methacrylate) grafts
Authors: Xie Hong‐Quan , Zhou Shi‐Biao
Published: April 2003

Terpolymers with uniform poly(methyl methacrylate) (PMMA) grafts were prepared by terpolymerization of PMMA macromonomer, butyl acrylate, and acrylic acid in benzene using AIBN as initiator. During terpolymerization the macromonomer polymerizes faster than the monomers at the beginning but slower at the latter stage. The terpolymers were purified by solvent extraction and fractional precipitation. The average grafting number per chain of the terpolymers was determined to be 3–8. Ionomers were obtained by neutralization of the terpolymers with alkali hydroxide or metallic acetate. Dynamic mechanical spectrum of the ionomer shows the existence of two Tg's, which implies the occurence of microphase separation. The ionomer exhibits high damping over a temperature range from −25 to 100°C. Both PMMA grafts and metallic carboxylate content raise the tensile strength of the ionomer and lower the ultimate elongation. The tensile strength of ionomers neutralized with different metallic ions decreases in the following order: Pb2+ > Zn2+ > Na+ > Ca2+ > Mg2+ > K+. The ionomers with uniform PMMA grafts show much better mechanical properties than the terpolymer without neutralization or the ionomer without PMMA grafts.
Structure and ESR investigation of plasma‐polymerized film of hexafluoropropene
Authors: Wang Daike , Chen Jie
Published: April 2003

The structure and constitution of plasma‐polymerized film of C3F6 (PPHFP) have been investigated by measuring its ESCA, 19F‐NMR, and IR spectra. It is found that the PPHFP film was a high degree of branching and 57% of quaternary carbons are linked to CF3 groups. It is also found that the constitution of PPHFP film is changed greatly at high power and a large amount of Si and O atoms are linked to the PPHFP chains. Furthermore, using element analysis, ESCA, and theoretical calculation by electronegative model, we found that the nitrogen atoms get into the PPHFP chains when using N2 as plasma gas. Besides, the radical concentration in the film is obtained to be 9.97 × 1019 spins/g and its half‐life is about half a year at room temperature in Ar gas. Having investigated decay process of the radicals in two gases of air and Ar, we calculated the activation energies and rate constants of radical recombination and oxidation reactions at different temperatures.
Polypeptide spheres. VII. Macroreticulation of spherical poly(γ‐methyl‐L‐glutamate) beads
Authors: Ihara Hirotaka , Furusawa Hideki , Li Xin , Hirayama Chuichi
Published: April 2003

Spherical beads from poly(γ‐methyl‐L‐glutamatate) alone were prepared using various diluents for macroreticulating by the “suspension and evaporation” method. The porosity and the pore size of the beads obtained were remarkably dependent on the chemical structure of a diluent. This is related to the specific miscibility of a diluent with poly(γ‐methyl‐L‐glutamate). For example, decahydronaphthalene made the beads much more macroporous than tetrahydronaphthalene with similar hydrophobisity: the aromaticity of diluent increases the miscibility. However, it was found that long‐chain alkyl compounds with a miscible group such as methyl dodecanoate, oleic acid, linoleic acid, and dialkyl‐phthalate were not only very effective for macroreticulating, but also induced narrow pore‐size distribution. In addition, the diluent influenced physicochemical properties of the beads to cause specific affinity to proteins.
Permeation of dissolved carbon dioxide in synthetic membranes
Authors: Nakagawa Tsutomu , Naruse Atsuko , Hicuchl Akon
Published: April 2003

Permeability coefficients of dissolved carbon dioxide in poly(dimethyl siloxane), plasmatreated poly(dimethyl siloxane) membranes, and other membranes were measured by applying a carbon dioxide electrode in a liquid to liquid diffusion cell. The apparent permeability coefficients of carbon dioxide polystyrene, low density polyethylene, and nylon membranes in a liquid phase were observed to be higher than those in a gas phase due to a plasticizing effect of water molecules in the membranes. Boundary layer's resistance was estimated for plasma‐treated and nontreated poly(dimethyl siloxane) membranes. The plasma treatment (10 W for 1 min in this study) which makes hydrophilic surfaces without change of bulk polymer properties was found to be effective to decrease the boundary layer's thickness and to increase the apparent permeability coefficient in the liquid phase.
Mechanistic study on photocuring of a methacrylates copolymer by benzophenones
Authors: Ito Yoshikatsu , Aoki Yasushi , Matsuura Teruo , Kawatsuki Nobuhiro , Uetsuki Masao
Published: April 2003

The types of photochemical reactions that will occur in the photosensitive resin for optical devices, poly(methyl methacrylate‐co‐crotyl methacrylate) (PMMA–CMA) doped with meta‐benzoylbenzophenone (BBP), were investigated. Oxetane formation, hydrogen abstraction followed by radical coupling, and pinacol formation were found to occur. The quantum yield for disappearance of benzophenone (BP) in the PMMA–CMA film was estimated as 0.68. The pendant crotyl group seems to be a major photoreaction site.
Effect of thermal pretreatment on the fracture behavior of polycarbonate in medium strain rate tensile tests
Authors: Pääkkönen E. J.
Published: April 2003

The fracture properties of as‐received and annealed (48 h at 403 K) commericial polycarbonates (PC) were examined in tensile tests with an average strain rate of ė = 2 s−1. Both materials were subjected to tensile tests at temperatures ranging from 223 to 423 K. The results were processed by a computer interfaced to the testing machine. The tensile strength of the annealed (pretreated) PC was superior to that of the as‐received (untreated) material. The elongation at break and the fracture energy, then, decreased due to annealing at all temperatures, yet followed impact strength curves. Fracture analysis and fracture morphology revealed clear differences in the behavior of the materials. Fracture nucleation occurred commonly at several points in the pretreated specimens, whereas only one nucleation point was found in the untreated specimens. Shear yielding morphology, which indicated plastic deformation, started to appear at a lower temperature in the pretreated specimens than in the untreated ones.
Poly(ethylene terephthalate)/polyarylate blends: Influence of interchange reactions on the melting behavior of poly(ethylene terephthalate)
Authors: Eguiazábal J. I. , Cortázar M. , Iruin J. J.
Published: April 2003

The influence of the interchange reactions of poly(ethylene terephthalate) (PET)/polyarylate (PAr) blends on the melting behavior of isothermally crystallized PET has been studied. PET shows three melting endotherms in the pure state and also when mixed with PAr. These endotherms are explained in terms of primary and secondary crystallization processes as well as recrystallization during the calorimetric scan. It is also shown that interchange reactions hinder the crystallization processes of PET.