bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural study of fractionated hydroxyethyl‐amylopectin in aqueous solution
Authors: Sarazin D. , Fraņois J. H. , Verwaerde C. , Fléche G.
Published: April 2003

Fractionated hydroxyethyl starch was well characterized by coupled LALLS‐SEC (lowangle laser light scattering and steric exclusion chromatography), QELLS (quasi‐elastic laser light scattering), MALLS (multiangle laser light scattering), and viscosimetry. The scaling laws of the molecular weight dependences of the following dimensions are found to exhibit low exponents consistent with a highly grafted structure:

Additional X‐ray synchrotonic scattering (SAXS) studies permit us to give a preliminary description of the internal structure of the macromolecules.
FTIR analysis of electrodeposition film from emulsion of two cationic resins
Authors: Yang Chin‐Ping , Chen Yahn‐Haur
Published: April 2003

The resin composition of film deposited from coemulsion of two cationic resins (epoxy–amine adduct,E, was the main resin; cationic trimethylolpropane‐toluene diisocyanate–dimethylaminoethanol/2‐ethylhexanol resin,T, was used as crosslinker) was determined by Fourier Transform Infrared (FTIR) quantitative analysis. The electrodeposition properties of cationic resins and their coemulsions were compared to study the effects of resin composition of coemulsions on the resin composition of deposited films. The optimum resin composition of coemulsions was also found to produce deposited film with the best properties after curing.
Near‐infrared probe for in situ characterization of nafion thin films
Authors: Zen Jyh‐Myng , Lipowska Malgorzata , Patonay Gabor
Published: April 2003

A near‐infrared (NIR)‐absorbing cyanine dye was used as a probe for in situ characterization of Nafion thin films. This NIR dye was very sensitive to changes in the hydrophobicity of the environment and proved to be very suitable for probing the Nafion coatings, which involve a two‐Phase structure of hydrophobic and hydrophilic zones. Sorption phenomena of water and aqueous alkali salt solutions by Nafion were investigated. For our study systems of thin‐coating films prepared from 5% wt alcoholic solution of Nafion 117, the absorption spectrum was dominated by higher‐order aggregates when in dry form. In pure water, the absorption maximum of the monomer dye appears at 773 nm and can be used as an indication of the swelling process of the film. The water uptake reaches saturation in only a few seconds. After the swelling process, an additional absorption band with a maximum at 555 nm appears primarily at the expense of the NIR monomer dye absorption band. The peak transition process, which is a very slow process and is a strong function of the water content inside the matrix, can be used as an indication of the establishment of equilibrium between the two‐phase structure due to the water uptake. Since the absorption maximum of the study system is around 800 nm, semiconductor lasers can be used. This technique shows high potential in other applications where polymers are used as support material, e.g., in situ thin‐film thickness measurements. In the study, the feasibility of this approach was illustrated.
Poiseuille flow of a power–law fluid between coaxial cylinders
Authors: Prasanth N. , Shenoy Uday V.
Published: April 2003

An analytical expression is derived, which permits direct evaluation of the volumetric flow rate or the pressure gradient for the laminar flow of a power–law fluid in a concentric annulus. The derivation is valid for tangential as well as axial flow, provided a parameter q, in the problem formulation, is substituted by appropriate binary values. The final flow rate solution is in the form of an elegant algebraic equation (not a definite integral) and holds for all values of the power–law index (not merely reciprocal integers). Attention is focused on the tangential pressure flow problem, where the zero‐shear plane does not coincide with the location of the maximum velocity. © 1992 John Wiley & Sons, Inc.
The removal of carbon tetrachloride from chlorinated polyisoprene using carbon dioxide
Authors: Burgess A. N. , Jackson K.
Published: April 2003

This study demonstrates the use of supercritical carbon dioxide in the removal of residual carbon tetrachloride from chlorinated polyisoprene in a packed column. The effects of varying temperature and pressure on the efficiency of extraction are examined. The data indicate that there exists an optimum combination of pressure and temperature and that quite small deviations from these conditions can produce substantially poorer extraction efficiency and lead to the destruction of the polymer particle morphology.
Thermal stability of polyacrylonitrile in the melt formed by hydration
Authors: Min Byung Ghyl , Son Tae Won , Jo Won Ho , Choi Soo Ghil
Published: April 2003

Differential scanning calorimetry (DSC) and intrinsic viscosity measurement have been used to investigate the thermal stability of PAN‐based copolymer in the melt formed by hydration. Samples containing various water contents were annealed at temperatures between 160 and 180°C for periods up to 60 min. The melting point (Tm) and crystallization temperature (Tc) increased with annealing time, irrespective of annealing temperature and water content. The increase in Tm with annealing time was interpreted in terms of thermodynamic parameters. The decrease in the heat of fusion (ΔHf) with the increase of annealing time implies that the number of nitrile groups is reduced during annealing in the melt. The decrease in the entropy of fusion (ΔSf) calculated from Tm and ΔHf suggests that the polymer chain becomes more rigid as the annealing time (or temperature) increases; however, the intrinsic viscosity does not increase during annealing. From both thermodynamic analysis and intrinsic viscosity, it is concluded that the increase in Tm is caused by chain rigidity mainly due to the intramolecular cyclization of nitrile groups. © 1992 John Wiley & Sons, Inc.
Bending of ionic polymer gel caused by swelling under sinusoidally varying electric fields
Authors: Shiga Tohru , Hirose Yoshiharu , Okada Akane , Kurauchi Toshio
Published: April 2003

Deformation of poly(vinyl alcohol)–poly(sodium acrylate) composite hydrogel (PVA–PAA gel) under sinusoidally varying electric fields was studied in electrolyte solutions. The PVA–PAA gel was prepared by repeatedly freezing and thawing a mixed solution of PVA and polyacrylic acid. A cyclic bending–straightening motion of the PVA–PAA gel rods of about 1 mm in diameter have been observed in Na2CO3 aqueous solutions under the fields. The PVA–PAA gel had a response time of less than several hundreds milliseconds. The bending has also been observed in organic solvents containing an electrolyte when the organic solvent is electrolyzed. It was found that the motion of the gel under electric fields of less than 1 Hz occurred mainly through swelling due to the change of the osmotic pressure based upon the difference of the ion concentration. However, it has not been determined whether the motion at higher frequencies is caused by the osmotic effect. © 1993 John Wiley & Sons, Inc.
The damage zone in microlayer composites of polycarbonate and styrene—acrylonitrile
Authors: Shin E. , Hiltner A. , Baer E.
Published: April 2003

The irreversible deformation behavior of coextruded microlayer composites, consisting of 49 alternating layers of polycarbonate (PC) and styrene—acrylonitrile polymer (SAN), was examined in the triaxial stress state achieved at a semicircular notch during slow tensile loading. Variations in the proportions of PC and SAN were manifest as changes in the relative thicknesses of PC and SAN layers. When the SAN layers were thicker than the PC layers (PC/SAN 25/75 v/v) or the layer thicknesses were about the same (53/47 v/v) the composites were only slightly more ductile than SAN and the deformation behavior of the layers mimicked that of the components. Examination of optical micrographs showed that the damage zone closely resembled that of SAN and consisted of internal notch crazes in the SAN layers that grew out from the notch surface in conformity with a mean stress condition. Shear processes became more evident when the PC layers were thicker than the SAN layers (PC/SAN 65/35 and 74/26 v/v). An unusual transition was observed in the SAN layers from internal notch crazing to interactive crazing and shear banding. The internal notch crazes ceased to grow when they terminated in a pair of microshear bands in the SAN layer. Subsequently a macroscopic shear‐yielding mode was observed as two sets of intersecting slip lines that grew out from the notch surface in both PC and SAN layers. Stress intensification caused by the plastic zone was responsible for the appearance of a second family of internal crazes in the SAN layers that originated in front of the notch tip. © 1993 John Wiley & Sons, Inc.
The brittle‐to‐ductile transition in microlayer composites
Authors: Shin E. , Hiltner A. , Baer E.
Published: April 2003

The brittle‐to‐ductile transition in continuous microlayer composites of polycarbonate (PC) and styrene–acrylonitrile copolymer (SAN) was investigated under the triaxial tensile stress state achieved at a semicircular notch. The availability of microlayer compositions with variations in the proportion of the components and also variations in the total number of alternating layers made it possible to examine the transition from SAN‐like, relatively brittle behavior, to PC‐like properties where the ductile component dominated yield and failure. Examination of the damage zone that formed at the notch root revealed that cavitational mechanisms dominated in the brittle composites that were those with the highest proportion of SAN and fewest number of layers. Shear‐yielding modes characteristic of PC dominated the damage zone of the ductile composites. Cavitational mechanisms were almost totally absent in these compositions that included those with the highest proportion of PC and the largest number of layers. A broad range of transitional behavior was observed with intermediate compositions where elements of both cavitational mechanisms and shear modes were superimposed. These compositions provided an opportunity to examine the interaction of cavitational and shear processes at the macro‐ and microscales. © 1993 John Wiley & Sons, Inc.
Sticky poly(vinyl alcohol) hydrogels
Authors: Cha Won‐Ill , Hyon Suong‐Hyu , Graiver Daniel , Ikada Yoshito
Published: April 2003

Low‐temperature gelation of poly(vinyl alcohol) (PVA) solution was performed in the presence of CaCl2. The resulting PVA hydrogels showed high stickiness and excellent water‐holding ability. These properties became more remarkable with increasing CaCl2 concentration in solvent. Furthermore, both the peel strength on stainless steel and the degree of swelling of the PVA hydrogel drastically increased as CaCl2 concentration was increased from 20 to 30 wt %. It is concluded that the sticky and water‐holding properties of PVA hydrogels are intimately related to the state of hydration of Ca ions in aqueous environment. © 1993 John Wiley & Sons, Inc.
The effect of surface modified polytetrafluoroethylene on polyacetal/polytetrafluoroethylene blends
Authors: Chiang Wen‐Yen , Huang Chi‐Yuan
Published: April 2003

Five kinds of blends: polyacetal (POM) and polytetrafluoroethylenes (PTFEs) [pure (PTFE), coupling agent coated (LZ‐PTFE), chemical‐treated (CPTFE, containing NaF salt), chemical‐treated (WPTFE, no NaF salt), coupling agent coated WPTFE(LZ‐WPTFE)] were prepared by mechanical blending. The PTFE presented in the blends, had good wear resistance properties. However, the adhesion interaction between the POM and the PTFE was poor, and increasing the PTFE content caused a decrease in the mechanical properties. Using the chemical surface treatment method to etch PTFE could cause treated‐PTFE to homogeneously disperse in POM. This result caused the POM/treated‐PTFE blends to have higher mechanical properties than those of the POM/PTFE blends. The NaF salt that adsorbed on the CPTFE surface acted as a coupling agent and offered a very strong adhesion interaction between the POM and the CPTFE. The free salt also acted as a nuclei to aid POM in crystallizing. As a result, the POM/CPTFE blends possessed the highest mechanical properties of all the blends and the best wear resistance property of POM/modified‐PTFE(LZ‐PTFE, LZ‐WPTFE, WPTFE, CPTFE) blends. © 1993 John Wiley & Sons, Inc.
Characterization of oligomers from 1,4‐butanediol and toluene diisocyanate
Authors: Lesar Meta , Z̆igon Majda , Malavas̆ic̆ Tatjana
Published: April 2003

Polyurethane oligomers from 1,4‐butanediol (BD) and toluene diisocyanate (TDI) with a various excess of BD were synthesized. Their molar masses were measured by gel permeation chromatography and the molar mass distribution correlated with the statistic theory. 1H‐, 13C‐, 1H–1H‐COSY–, ATP–, and 15N‐NMR spectra of reaction products were recorded, and from the ratio of proton integrals of characteristic terminal and inner urethane groups, the reactivity ratio of the para and ortho NCO groups in 2,4‐TDI was calculated to be approximately 1.8 at a lower excess of BD. 15N‐NMR spectroscopy was found not to be selective enough to detect small amounts of side reactions. © 1993 John Wiley & Sons, Inc.
Unified modeling technique for high‐viscosity, melt‐phase, condensation polymer reactors
Authors: Sampson Kendree J. , Neogi Swati , Medlin James C.
Published: April 2003

Mathematical models for chemical reaction and mass transfer occurring in the manufacture of high‐viscosity condensation polymers are considered. A preliminary study indicates that several diverse models can be represented using a single formula based upon an effectiveness factor. The effectiveness factor is shown to depend upon a ratio of time scales of mixing and reaction. The formula giving the effectiveness factor in terms of the time scales ratio is shown to depend upon mixing assumptions only. Starting with a mixing‐cell model, a new modeling framework is developed and shown to include the previous models as special cases. The framework is free of inherent mixing assumptions and can be applied to a wide variety of situations once the mixing characteristics are specified. © 1993 John Wiley & Sons, Inc.
Electrosynthesis of conducting poly(p‐phenylene)
Authors: Bhadani Suraj N. , Gupta Sumanta K. Sen , Gupta Manoj K. , Prasad Jagdeo
Published: April 2003

The polymerization of benzene was studied in bulk and in nitrobenzene using BF3O (C2H5)2 as a supporting electrolyte at platinum electrodes to obtain poly(p‐phenylene). The polymers were formed as a black thready mass on the anode and their yields were restricted to the area of the anode in the electrochemical cell. The yields of the polymers formed in the bulk and in nitrobenzene were almost equal, although electrical resistances of the polymers obtained from the bulk were relatively lower. Cyclic voltammetry measurements suggest that the polymerization of benzene took place from the species generated anodically in situ. © 1993 John Wiley & Sons, Inc.
Nonlinear optical properties of solution of the substituted polyaniline
Authors: Wan Meixiang , Yang Jiping , Jiang Qian , Mi Xin , Ye Peixian
Published: April 2003

Nonlinear optical properties of solution of substituted polyaniline (PANI), such as polytoluidine (POT), Br–POT, and Br–PANI, were measured by the degenerate four‐wave mixing (DFWM) method as a function of the concentration of solution and the protonation state. The observed nonlinear optical properties are intrinsic and might be related to the resonance effect and the photoexcitation of the molecule on the quinoid ring of the polyemeraldine chain. © 1993 John Wiley & Sons, Inc.
Properties of cation‐exchange membranes prepared by radiation grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymers
Authors: Kostov G. K. , Atanassov A. N.
Published: April 2003

Some properties of the ion‐exchange membranes prepared by simultaneous and preirradiation techniques of grafting of acrylic acid onto tetrafluoroethylene–ethylene copolymer films, including porous microfilters, have been studied. The water content, electric resistance, transport number, distribution of grafting, thermal and chemical stability, and mechanical characteristics of the membranes were determined as a function of the grafting degree. Graft polymerization proceeds from both surfaces of the polymer film into the polymeric matrix depth. Cation‐exchange membranes prepared possess good electrochemical and mechanical properties, high thermal and chemical stability at grafting degrees from 30 to 50%, and can be successfully used in electrodialysis processes. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal applications. VII. Aggregate formation of lipophile‐modified polyacrylates in aqueous solutions
Authors: Kuo Ping‐Lin , Hung Min‐Nan , Lin Yueh‐Hsien
Published: April 2003

Water‐soluble copolymers, poly(dodecyl acrylate–coacrylic acid) (PDA), are synthesized by copolymerizing different ratios of dodecyl–acrylate/acrylic acid. Their aqueous solutions are transparent. The plots of I1/I3 (the intensity ratio of pyrene emission at 374 nm and 385 nm) and of surface tension as a function of polymer concentrations are combined to verify the existence of the aggregates of PDAs. It is found that the aggregations begin to form at concentrations below that of the polymer transfer to the air–water interface. The plots of I1/I3 as a function of polymer concentration shows that the polymers with a higher ratio of dodecyl acrylate form polymer aggregates at lower concentrations. The hydrophobicity of the inner core of polymer aggregates is close to that of sodium dodecyl sulfate (SDS). Polymer solutions of PDA 30, PDA 30L, and PDA 15, show significant solubilization ability to pyrene. (The molar ratio of dodecyl acrylate/total acrylates is 30%, 30%, and 15% for PDA 30, PDA 30L, and PDA 15, respectively. L, low molecular weight.) The solubilization ability increases with the increase in polymer concentration and degree of substitution of dodecylamine. The intensity ratio of the excimer emission to monomer emission of pyrene (Ie/Im) increases with increasing polymer concentration, roughly parallel to the increase in the amount of pyrene solubilized. However, the Ie/Im at a fixed pyrene concentration (Ie/I) decreases with increasing polymer concentration. These phenomena are interpreted in terms of the amount of pyrene solubilized and the size and concentration of the polymer aggregates. © 1993 John Wiley & Sons, Inc.
Thin films from 96% quinoline
Authors: Honeychuck R. V. , Cozzens R. F. , Shirk J. S. , Lindle J. R.
Published: April 2003

Films from 96% quinoline and from 96% quinoline with poly(1,4‐cyclohexylene carbonate), mesoporphyrin IX dimethyl ester, and Pd(II)mesoporphyrin IX dimethyl ester have been cast via heating and subsequent evaporation. The films are approximately 3 μm thick, with a maximum variation normal to the surface of 0.10 μm in 2 mm of surface travel. The optical quality of the samples formed from 96% quinoline alone is excellent and variable from the 96% quinoline/solute combinations. The third‐order nonlinear optical (NLO) properties of these materials have been examined. © 1993 John Wiley & Sons, Inc.
Pervaporation of ethanol—water mixture by Co60 γ‐ray irradiation‐modified nylon 4 membrane
Authors: Lai Juin‐Yih , Chen Rong‐Yuh , Lee Kueir Rarn
Published: April 2003

The ethanol—water separation by pervaporation with γ‐ray irradiation‐modified nylon 4 membrane was investigated. The membrane was prepared by homografting γ‐ray irradiation of vinyl acetate (VAc) monomer onto nylon 4, poly(vinyl acetate) (PVAc)‐homo‐g‐nylon 4 followed by hydrolysis treatment, poly(vinyl alcohol) (PVA)‐homo‐g‐nylon 4. The homografting method shows significant improvement in the degree of grafting of (VAc) onto nylon 4 over the heterografting method. For example, the degree of grafting of the VAc with 30 vol % and total dose of 2 Mrad for the heterografted method and for the homografted method are 14.1 and 42.2%, respectively. The effects of irradiation with or without oxygen in solution, irradiation time, VAc content, degree of grafting, crystallinity, feed concentration, and operating temperature on performances of the PVA‐homo‐g‐nylon 4 membrane were carried out. Comparison of the separation factor of sorption in membrane (αsorp) and that of pervaporation (αperv) was made. A separation factor of 7.3 and a 0.691 kg/m2 h permeation rate can be obtained by the PVA‐homo‐g‐nylon 4 membrane with a degree of grafting of 42.2% for 90 wt % ethanol feed concentration. Compared with the unmodified nylon 4 membrane, which has the separation factor of 4 and permeation rate of 0.350 kg/m2 h, the PVA‐homo‐g‐nylon 4 membrane shows improved a separation factor and permeation rate. © 1993 John Wiley & Sons, Inc.
Phase behavior of mixtures of tetrabromobisphenol‐A polycarbonate in solvents and nonsolvents
Authors: Beck H. N.
Published: April 2003

The relative solubility and phase relationships are presented for ternary mixtures consisting of the polymer tetrabromobisphenol‐A polycarbonate in three representative good solvents and nine nonsolvents. The effects of temperature, composition, compound structure, compound molecular weight, and hydroxyl concentration upon the relative solvent power of the liquid mixtures and thus upon the phase borders separating one phase from multiphase compositions are discussed. The importance of such information for the preparation of permselective membranes is emphasized. © 1993 John Wiley & Sons, Inc.
Gas permeabilities of poly(trimethylsilylpropyne) membranes surface modified with CF4 plasma
Authors: Lin Xiao , Xiao Jun , Yu Yali , Chen Jie , Zheng Guodong , Xu Jiping
Published: April 2003

Surface fluorination of poly(trimethylsilylpropyne) (PTMSP) membranes by CF4 plasma was studied. The surface fluorination of the membranes was carried out in an atmosphere of CF4 in a capacitively coupled discharge apparatus with external electrodes. Dramatic increase in selectivity (P/P) was observed. The effect of fluorination conditions such as duration of treatment and discharge power on the permeabilities of the membranes was studied. X‐ray photoelectron spectrometric data of modified PTMSP membranes showed a drastic alternation in the surface layer. The P and P/P of the membranes were observed to be dependent on the F/C atomic ratio. At F/C > 1, the P/P value of the membranes could be more than four. © 1993 John Wiley & Sons, Inc.
Radiation‐induced sol‐gel transition of protein: Effects of radiation on diffraction property
Authors: Nisizawa Mizuho
Published: April 2003

Solid gelatin was irradiated with 60Co gamma rays, and the effects of radiation on the diffraction property of the protein molecule were studied by measuring the X‐ray diffraction intensity at different radiation doses and elapsed times after irradiation. The effects of radiation on the ordered conformation of the protein molecule were discussed. © 1993 John Wiley & Sons, Inc.
Single‐ion conduction and lithium battery application for ionomeric cross‐linking polymer
Authors: Zhang Sheng Shui , Wan Guo Xiang
Published: April 2003

The single‐Li+ conduction of the cross‐linking poly [oligo (oxyethylene) methacrylate‐co‐lithium methacryloyl hexylsulfonate]s was studied, and an Li+ ionic transport number of 0.994 estimated from the isothermal transient ionic current (ITIC), in which an ion‐blocking platinum electrode was used. The results show that Li+ ‐ionic conduction can be reasonably described by Vogel–Tammann–Fulcher (VTF) equation, suggesting that there is close correlation between ionic migration and segmental motion in these polymers. The battery composed of lithium/this copolymer film/polyaniline supplied a constant short circuit current (JSC) of 45 μA/cm2 and an open circuit potential (VOC) of 3.6 V at 25°C. © 1993 John Wiley & Sons, Inc.
Influence of curative, filler, compatibilizer, domain size, and blend ratio on the dynamic mechanical properties of silicone–EPDM blends
Authors: Kole Swapan , Bhattacharya Ashis , Tripathy D. K. , Bhowmick Anil K.
Published: April 2003

Dynamic property measurements show two loss tangent peaks for silicone rubber at about −95°C and −20°C, and one peak for EPDM at about −30°C. DSC studies confirm that the first loss tangent peak of silicone rubber is caused by its glass transition and the other is caused by crystalline melting of silicone. Measurements with blends reveal the individual characters of the components in the blends. Large differences in the solubility parameter between them also explains the incompatible nature. The effects of curative, blend ratio, and ageing are found on the glass‐transition temperature and also on the storage modulus and loss tangent. Although filler does not change the glass‐transition temperature, it changes the dynamic properties. Silane‐grafted EPR shows an optimum concentration as a compatibiliser, resulting in improved mechanical properties of the blends. The domain size of the blends also reduces with the introduction of the compatibilizer. Imposition of restriction on the domains by partial curing during mixing results in materials with higher storage modulus. The morphology study indicates an interpenetrating network structure for these restricted domain blends. © 1993 John Wiley & Sons, Inc.
Viscosity, yield stress, slip, and natural convection of HSPAN gel–water dispersions
Authors: Hardin Richard A. , Burmeister Louis C.
Published: April 2003

Three hydrolyzed‐starch–polyacrylonitrile (HSPAN) copolymer materials tested as gel–water dispersions in a Brookfield rotating spindle viscometer exhibited velocity slip at solid boundaries and a yield stress. Dispersions with 0.5% HSPAN concentrations were about 20,000 times more viscous than water when the shear stress surpassed the yield stress and viscous power‐law flow ensued. The apparent viscosity of an HSPAN gel–water dispersion was reduced by nearly an order of magnitude when tap water was substituted for deionized water. The apparent viscosity of the HSPAN gel–water dispersions decreased by about 30% after the fluid was continuously maintained at a temperature of 80°C for 1 week, and by an order of magnitude or more after 3 weeks under those conditions. In natural convection tests, the yield stress enabled an HSPAN gel–water dispersion to withstand greater temperature differences across a horizontal layer before inception of natural convection than a fluid without one. © 1993 John Wiley & Sons, Inc.
Polymerization of methyl methacrylate in 3‐component cationic microemulsion
Authors: Rodriguez‐Guadarrama L. A. , Mendizabal E. , Puig J. E. , Kaler E. W.
Published: April 2003

Methyl methacrylate has been polymerized in three‐component o/w microemulsions made with the cationic surfactant dodecyltrimethylammonium bromide (DTAB). The effects of temperature type and concentration of initiator (AIBN or potassium persulfate), and surfactant and monomer concentration on polymerization kinetics are investigated. Final conversions and reaction rates increase with increasing monomer and initiator concentrations and with higher reaction temperatures. The rate of polymerization shows initiation and termination intervals, but no constant rate interval is observed. Both molecular weight and particle size decrease as the concentration of initiator increases, regardless of type of initiator. Latexes with small particle size (< 70 nm) and high molecular weights (>106) were obtained in all cases. Activation energies for the microemulsion polymerization of MMA with AIBN (10.3 kcal/mol) and KPS (13.4 kcal/mol) are smaller than that of bulk polymerization using AIBN (20 kcal/mol). © 1993 John Wiley & Sons, Inc.
Elastic properties of random‐linked cis‐PB networks: A characterization and gel point study
Authors: Pyckhout‐Hintzen W. , Müller B. , Springer T.
Published: April 2003

cis‐Polybutadiene networks with microstructure 98% cis, cross‐linked in the bulk state by gamma irradiation, were characterized in terms of their mechanical properties. Data from stress‐strain analyses, swelling degrees, stress relaxation, and random‐linking theory are in accordance and the estimated gel points practically coincide. Trapped entanglements lead to a 30% increase in the network modulus, from which also the plateau modulus, 0.71 ± 0.09 MPa, was determined. The tensile data were obtained from Mooney‐Rivlin representations without junction constrained corrections. Preliminary stress‐relaxation experiments indicated a slow relaxation at room temperature. It can be concluded that the assumption of additive contributions from chemical and entanglement cross‐link densities in the Langley theory works well in the range of doses investigated here. © 1993 John Wiley & Sons, Inc.
Functionalization of polyester PET fibers
Authors: Arroyo Miguel , Tejera María , Ibarra Luis
Published: April 2003

In order to promote chemical linkage between polyester PET fibers and thermoplastic or elastomer matrices, a diazide derivative has been synthetized and reacted with the free hydroxyl groups of the fibers. The completion of the reaction was controlled by means of IR spectroscopy and chemical analysis, and fiber characterization was carried out by thermogravimetric and DSC techniques. The obtained results permit the determination of the suitability of the synthetized diazide to functionalize PET fibers that could be used as reinforcing fibers for polymer matrices composites. © 1993 John Wiley & Sons, Inc.
New poly(bisbenzoylamine imide) series: Synthesis and characterization
Authors: Litauszki L. , Karasz F. E.
Published: April 2003

Three new series of poly(bisbenzoylamine imide)s, incorporating different aromatic diamines, have been synthesized. The polymers, obtained by the two‐step procedure, have been characterized by DSC, TGA, X‐ray, FTIR, and 1H‐NMR methods. Thermal analysis showed glass transition temperatures in the range of 200°–250°C and decomposition at 430°–495°C. Most DSC runs displayed an exothermic event above Tg that was due to cold crystallization of the polymer molecules. A melting point was not observed. The new polymers, even before annealing, showed sharp X‐ray diffraction patterns, evidence of semicrystallinity. The polymers, soluble in polar solvents, were analyzed by NMR in solution. Typical chemical shifts for the bisbenzoylamine protons were reported; FTIR spectra showed the characteristic imide peaks. Due to a near overlap of the carbonyl vibration of the imide group with the bisbenzoylamine carbonyl, the latter vibration was detected in only one series. © 1993 John Wiley & Sons, Inc.
Crystallization kinetics of poly(ethylene terephthalate) in compositions containing naturally functionalized triglyceride oil
Authors: Barrett L. W. , Sperling L. H. , Gilmer J. , Mylonakis S. G.
Published: April 2003

The crystallization of poly(ethylene terephthalate) (PET) in blends with naturally functionalized triglyceride oils and their networks has been investigated. Crystallization kinetics of PET in the presence of small amounts of castor oil is improved, both in cooling from the melt state, and in heating from the glassy state. In conjunction with the nucleating agent sodium benzoate, either chemically bonded to castor oil or as a simple mixture, even greater enhancements of crystallization are observed. The PET crystallinity in semi‐IPNs and blends of low to intermediate castor oil‐HMDI polyurethane content are higher than that of neat PET (on a per gram of PET basis). Crystallinity in compositions with a high triglyceride oil network content is greatly affected by the presence of the network, with large melting point depressions, and loss in overall crystallinity. In cases where the triglyceride oil network is completely formed in a miscible melt with PET, the PET is unable to crystallize on cooling, resulting in amorphous semi‐IPNs. Plasticization due to the oil, nucleation from added agents, bond interchange reactions between the oil and the PET, overall chemical composition, and the presence of a triglyceride oil network are found to have a controlling influence over the type and extent of PET crystallinity in the compositions. © 1993 John Wiley & Sons, Inc.
Characterization of nonideal networks by stress‐strain measurements at large extensions
Authors: Klüppel M.
Published: April 2003

It is shown how a characterization of unfilled, amorphous rubber networks can be evaluated from uniaxial stress‐strain measurement data. Beside the cross‐linking density, the relative scission probability during the curing procedure is evaluated, which determines the amount of dangling free chain ends and the number of trapped entanglements. These values are found from the C2 term of the Mooney‐Rivlin equation by using the predictions of a tube model. A necessary requirement for applying stress‐strain measurements at large extensions is the consideration of the finite extensibility component of the reduced stress. It is taken into account by using a numerical procedure, which derives from a series expansion of the inverse Langevin approximation. The experimental results found at natural rubber networks cross‐linked with thiuram (TMTD) and peroxid (DCP) show that network defects cannot be neglected in the DCP networks. They are assumed to be connected to the worse tensil strength properties compared to the TMTD networks. © 1993 John Wiley & Sons, Inc.
Orientation gradients at polymer surfaces. I. Description of methods
Authors: Chen Gangchi , Fina Leslie J.
Published: April 2003

A method capable of quantitative predictions of orientation gradients at the surface of polymers is proposed. It is based on the transformation of variable‐angle attenuated total reflected infrared intensities to absorption coefficients versus depth from the surface. Two alternate approaches have been used to demonstrate the viability of the method: computer simulation and sample analysis. Exact reflected intensities from anisotropic layered systems have been calculated with Fresnel coefficients. The exact intensities are used to reextract the orientation gradient with data transformation. This analysis demonstrates the conditions under which the variable‐angle method is expected to optimally perform. Simulation results clearly indicate high accuracy near the interface and low accuracy at remote distances. Thin films of isotropic and uniaxially drawn isotactic polypropylene are prepared and used as layered systems. Step functions in orientation can be accurately predicted only when some information is known prior to the gradient calculation. In uniaxially oriented thick films of polypropylene, the analysis indicates that the crystal phase is highly oriented at the surface and in the bulk. Within the first 2 microns from the surface, both the amorphous and crystal phases show negligibly small gradients in orientation. © 1993 John Wiley & Sons, Inc.
Viscosity effect in polyolefin ternary blends and composites
Authors: Kim Byung Kyu , Kim Myun Soo , Kim Kook Joong
Published: April 2003

Ternary blends of PP (80) /rubber (EPM, EPDM) (10) / PE (10) and PP (80) / rubber (10) / CaCO3 (10) composites were prepared in a twin‐screw extruder. With polyethylene (PE) viscosity comparable to, or higher than that of rubber, the dispersed phase formed a reticulate structure with reduced size. On the contrary, when the viscosity of PE was significantly lower than that of rubber, the dispersed phase formed almost homogeneous morphology. With reticulate morphology, PE crystallinity content, hardness, modulus, and elongation at break of the ternary blend increased. In polypropylene (PP) / rubber / CaCO3 composites, better dispersion of CaCO3 in the PP matrix was obtained when the viscosity of rubber was significantly higher than that of matrix. With better dispersion, hardness and tensile properties were improved, but the impact strength more or less decreased. © 1993 John Wiley & Sons, Inc.
ABA triblock copolymers with two crystallizable blocks
Authors: Kuo Wen Faa , Tong S. N. , Pearce Eli M. , Kwei T. K.
Published: April 2003

Triblock copolymers of the ABA type were synthesized in which the A block is poly(ethylene oxide) (PEO), having molecular weight of 1000 or 2000, and the B block is poly(dimethylsiloxane) (PDMS), having molecular weight of about 8000 or 10,000. When the triblock copolymer was cooled from the melt, the PEO block crystallized at around room temperature. Upon further cooling to liquid nitrogen temperature and reheating, the crystallization of the PDMS middle block took place at around −90°C. The melting temperatures and degrees of crystallinity of the PEO blocks in the copolymers were depressed from their respective pure state values. On the other hand, the melting points of the PDMS middle blocks in the copolymers were the same as the pure state values; furthermore, the degrees of crystallinity were unexpectedly much higher. © 1993 John Wiley & Sons, Inc.
Surface modification of polyethylene and magnetite powders by combination of fluidization and plasma polymerization
Authors: Inagaki N. , Tasaka S. , Ishii K.
Published: April 2003

A new surface modification process of powders was attempted, using the combination of fluidization and plasma polymerization techniques. This study shows that the combination of the fluidization and plasma polymerization techniques is useful in the surface modification of powders.

Polyethylene and magnetite powders were first fluidized, and then were modified in the fluidization state by the plasma polymers of tetrafluoroethylene (TFE). XPS spectra of the modified powders showed that the surfaces of the polyethylene and magnetite powders were coated with fluorine‐containing polymers, and that the polymers were mainly composed of CH, CF, and CF2 groups. The elemental composition (F/C atomic ratio) and the composition of the fluorinated carbons in the plasma polymers were dependent on the W/FM parameter, as well as the TFE concentration in the TFE/Ar mixture. It is emphasized that the W/FM parameter is a factor used to control the chemistry of the plasma polymerization reactions. The triboelectric charge of the magnetite powders, when modified by the plasma polymerization of the TFE/AR mixtures, was higher than the usnmodified by about two. The static electrification properties of the powders can changed by the plasma‐polymer‐coating. © 1993 John Wiley & Sons, Inc.
Humidity dependence of visible absorption spectrum of gelatin films containing cobalt chloride
Authors: Otsuki Soichi , Adachi Kimihiro
Published: April 2003

Gelatin films containing cobalt chloride were investigated to obtain information on the humidity dependence of optical absorbency in view of the coordinate state of cobalt ion and the polymer structure. The visible absorption spectra of the films exhibited that, with increasing relative humidity (RH), the absorption bands between about 550 and 750 nm decreased, accompained by sharpening of the 693 nm peak. Further, the decrease of cobalt chloride in gelatin resulted in decreased absorption intensity of the 693 and 668 nm peaks, more than the overall lowering in intensity. The infrared spectral data indicated that most of the carboxyl groups of gelatin are linked to the complex even in the strongly hydrated state. In addition, the water content of the films containing cobalt chloride is a little less below 42% RH, but is much greater above 62% RH than that of the original gelatin film. These results indicated that there are cross‐linked networks, composed of the hydrogen bonding and the coordination bond via the complex in the dry film; as water molecules are adsorbed by the film, they gradually destroy these bonds and swell the polymer. © 1993 John Wiley & Sons, Inc.
Extrusion processing of granular starch‐g‐poly(methyl acrylate): Effect of extrusion conditions on morphology and properties
Authors: Trimnell D. , Swanson C. L. , Shogren R. L. , Fanta G. F.
Published: April 2003

Starch‐g‐poly(methyl acrylate) copolymers (S‐g‐PMA) containing 10, 30, 46, and 58% PMA, by weight, were prepared by ceric ammonium nitrate‐initiated polymerization of methyl acrylate onto granular cornstarch. Graft copolymers were extrusion‐processed through a strand die with water contents of 10 and 30% (based on starch) and at temperatures of 140 and 180°C, and the resulting strands were then pelletized. Properties of ribbons prepared from extrusion‐processed S‐g‐PMA depended on the combined effects of processing temperature, PMA level in the graft copolymer, and water content during extrusion. Ribbon formation was poor at the lowest PMA level of 10%, and extruded ribbons did not have sufficient continuity for tensile testing. Ribbons with smooth surfaces were obtained with 10% water in the polymer, whereas a water content of 30% produced extrudates that were rough and pebbly. When processed with 10% water, graft copolymers containing 46 and 58% PMA exhibited the highest values for both ultimate tensile strength (UTS) and % elongation at break (%E) when the extrusion was performed at 180°C. UTS was reduced and %E was increased when the water content during processing was increased to 30%. At the highest grafting level (58%), discrete granules of S‐g‐PMA were still apparent in scanning electron micrographs of extruded ribbons. More granule disruption occurred when the PMA level was reduced to 46%, and virtually none of the original granule structure remained after extrusion with 30% water. The effect of water content during processing was especially apparent at the grafting level of 30%, and extrudate properties were consistent with the formation of starch as the continuous phase under high moisture conditions. The behavior of S‐g‐PMA granules during extrusion can be explained by cross‐linking within the starch matrix during the graft polymerization reaction. DSC data were consistent with this theory. © 1993 John Wiley & Sons, Inc.

This article is a US Government Work and, as such, is in the public domain in the United States of America.
Polyamides containing olefinic bonds
Authors: Mikroyannidis John A.
Published: April 2003

The reaction of 2,5‐dimethylpiperazine with a double molar amount of maleic anhydride afforded a new unsaturated dicarboxylic acid that was characterized by IR and 1H‐NMR spectroscopy. It was condensed with various aromatic diamines by the phosphorylation method to yield polyamides bearing olefinic bonds. They were readily soluble in polar aprotic solvents and certain acids. The DTA traces of polyamides showed exotherms above 250°C attributable to their cross‐linking through the olefinic bonds and a partial thermal degradation. Evidence for the cross‐linking of polyamides attained during their heat‐curing was obtained from the IR spectra of the uncured and cured samples. Thermal stabilities of cured (at 300°C for 15 h) polyamides were evaluated by TGA and isothermal gravimetric analysis. They were stable up to 321–336°C in N2 or air and afforded an anserobic char yield of 61–71% at 800°C. © 1993 John Wiley & Sons, Inc.
A study of the interaction of mechanically generated polypropylene radicals with phenolic antioxidant in the presence of oxygen by EPR spectroscopy
Authors: Hloušková Zuzana , Lustoň Jozef , Szöcs František
Published: April 2003

Isotactic polypropylene (iPP) was mechanically degraded in the absence and presence of a phenolic antioxidant at liquid nitrogen temperature in the presence of oxygen. The interaction of the primarily formed iPP macroradicals with oxygen and phenol was studied by EPR spectroscopy in the temperature region between 77 and 303 K at antioxidant concentrations of 0.1, 0.5, and 3.0 wt%. It was found that iPP macroradicals react at low temperature with oxygen, yielding peroxy radicals, and with antioxidant, with a simultaneous formation of phenoxy radicals. The development and decay of all kinds of radicals was studied. The rate constants for peroxy radical decay were determined and the apparent activation energies for the regions of slow and fast decay were calculated. © 1993 John Wiley & Sons, Inc.
Surface microstructure of MMA‐HEMA polymer membranes
Authors: DomíNguez J. M. , Palacios J. , Espinosa G. , Schifter I.
Published: April 2003

A series of MMA‐HEMA polymer (hydroxyethyl methacrylate) membranes were prepared using several copolymer precursor mixtures and were characterized by transmission and scanning electron microscopy. The correlation between the preparation methods and the microstructure of the porous layers was sought. The cryofracture procedures also were investigated in order to observe the polymer membranes in the electron microscope. It was found that the porosity of the intermediate transport layer depends on the molecular weight composition and the MMA/HEMA copolymer ratio; the presence of dimethylformamide (DMF) also has a marked influence on the microtextural properties of the transport layer. The main features of the selective layer surface are the very fine roughness, with pits and pores in the 1‐5 nm range, and the chainlike protuberances at the nanometer scale. The cryogenic fracture methods proved adequate for observation of the new MMA‐HEMA‐type membranes without artifacts. © 1993 John Wiley & Sons, Inc.
Hydrophilic surface modification of polypropylene films by CCl4 plasma
Authors: Inagaki N. , Tasaka S. , Imai M.
Published: April 2003

The CCl4 plasma treatment of polypropylene films was investigated from the viewpoint of hydrophilic surface modification using a contact‐angle meter, ATR FTIR spectroscopy, and angular XPS. Hydrophilicity and chemical composition of the CCl4 plasma treatment was effective in hydrophilic modification. The advancing contact angle of water for polypropylene films was decreased from 99° to 81‐7° by the CCl4 plasma treatment, and the surface energy increased from 27.2 to 38.9‐67.7 mJ/m2 when the discharge current varied from 50 to 150 mA. The CCl4 plasma initiated chlorination, oxidation, and aluminum sputtering reactions. The chlorination of polypropylene films was favorable in a mild CCl4 plasma operated at discharge current of 50 mA. The oxidation and aluminum sputtering reactions were predominant over the chlorination in strong CCl4 plasmas operated at discharge currents of more than 75 mA. The chlorination initiated by the mild CCl4 plasma was restricted near the film surface within 36 Å deep. The regions modified with the strong CCl4 plasma reached inner layers of 36‐49 Å deep. Hydrophilicity caused by the CCl4 plasma treatment may be due not only to chlorine functionalities but also to oxygen and aluminum functionalities. © 1993 John Wiley & Sons, Inc.
Development of polyurethane engineering thermoplastics. II. Structure and properties
Authors: Frontini Patrica M. , Rink Marta , Pavan Andrea
Published: April 2003

Rigid, tough thermoplastic polyurethanes were synthesized by a two–step technique. These materials presented a complex structure consisting of a continuous, rigid, amorphous, or semicrystalline matrix with a dispersed soft phase. The influence of soft–segment content upon rigidity modulus, heat–distortion temperature, and fracture behavior has been deter‐mined on model amorphous polyurethanes. The influence of crystallinity upon final prop‐erties has been studied on two materials: a preparation of ours and a commercial product. Various degrees of crystallinity have been induced in the samples by annealing. Phase structure was characterized by differential scanning calorimetry and wide–angle X–ray scat‐tering. Some of the polyurethane samples assayed in this paper exhibited similar properties to those reported in respect of more conventional engineering thermoplastics, such as ABS or nylon. © 1993 John Wiley & Sons, Inc.
Effect of melt‐state curing on the viscoelastic properties of poly(phenylene sulfide)
Authors: Scobbo James J.
Published: April 2003

Low molecular weight, low viscosity poly(phenylene sulfide) (PPS) has been cured in the melt state to examine effects of curing time and temperature on the melt‐state dynamic viscoelastic behaviour. It was found that the Newtonian behaviour of the uncured material could largely be retained if melt cure temperatures are properly controlled. This result is in contrast to solid‐state curing, where the Newtonian nature of the resin is reduced, pre‐sumably due to increased branching and cross‐linking as molecular weight builds. The current result indicates that melt‐state curing may provide a high molecular weight PPS resin with a predominantly linear molecular architecture. © 1993 John Wiley & Sons, Inc.