bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of MMA on the physical properties of urethane–methacrylate
Authors: Santhana Gopala Krishnan P. , Choudhary Veena , Varma I. K.
Published: April 2003

Urethane prepolymer was prepared by reacting two moles of tolylene diisocyanate with one mole of poly(ethylene glycol) (mol wt 400), followed by end‐capping with two moles of 2‐hydroxyethyl methacrylate at room temperature (30 ± 1°C) in the presence of stannous octoate as catalyst. Different proportions of methyl methacrylate (MMA) were added to the urethane prepolymer in order to study the effect of composition on mechanical properties. Sheets were fabricated by adding 1% azobis (isobutyronitrile) (w/w) to this solution. All the copolymer sheets had a transmittance similar to the PMMA sheet, in the wavelength range of 400–800 nm. Tensile strength and modulus decreased with decreasing MMA content, whereas percent elongation at break increased. All the samples showed 2–3 stages of degradation. Initial decomposition temperature increased with increasing carbamate content. © 1993 John Wiley & Sons, Inc.
Investigations for obtaining semi‐interpenetrating polymer networks based on monomers of different reactivity toward radicals
Authors: Derrough S. N. , Rouf C. , Widmaier J.‐M. , Meyer G. C.
Published: April 2003

Classically, the one‐step synthesis of interpenetrating polymer networks (IPNs) and related materials requires noninterfering polymerization modes to achieve distinct networks, held together by only physical entanglements. For the combination of (meth) acrylic and allylic monomers, both polymerizable by free radicals, a new in situ sequential synthesis for obtaining semi‐IPNs is proposed. Using specific initiators that decompose at two different temperatures, refractive index measurements, Fourier transform infrared spectroscopy, and dynamic mechanical analysis have shown that neat species are formed and that the two monomers do not copolymerize. © 1993 John Wiley & Sons, Inc.
Search for nonoxidative, hydrogen‐abstracting initiators useful for melt grafting processes
Authors: Xie Haiqi , Seay Michelle , Oliphant Ken , Baker Warren E.
Published: April 2003

Using organic peroxide initiators in the melt grafting of monomers containing amino groups onto polyethylenes is known to cause serious discoloration of the resulting polymers. To eliminate the discoloration while preserving the controlled degree of grafting, a nonoxidative and hydrogen‐abstracting initiator with appropriate thermal stability is needed. In this study, the hydrogen‐abstracting capability of three azo initiators with suitable decomposition rates in the melt grafting temperature ranges was evaluated using polyethylene cross‐linking and polypropylene degradation experiments (called “hydrogen‐abstracting experiments”). Among the three azo initiators tested, only a phenylazo initiator, 2 ‐ phenylazo ‐ 2,4 ‐ dimethyl ‐ 4 ‐ methoxyl ‐ valeronitrile (V‐19), demonstrated strong hydrogen‐abstracting capability from polymer backbones. These three azo initiators were used in the melt grafting of 2 ‐ (N, N ‐ dimethylamino) ethyl methacrylate (DMAEMA) and 2‐(N‐t ‐butylamino) ethyl methacrylate (tBAEMA) onto a linear low‐density polyethylene (LLDPE). In agreement with the results obtained from the hydrogen‐abstraction experiments, only V‐19 led to a considerable amount of grafting of both DMAEMA and tBAEMA onto LLDPE. As expected, polymers grafted with V‐19 showed significantly reduced discoloration compared with those grafted with peroxide initiators. Further examination of the grafting results indicated that the initiator efficieny, defined as the number of grafted monomer units per radical generated from initiator decomposition, was higher with the phenylazo initiator than with peroxide initiators. The hydrogen‐abstracting capability of the phenyl free radical generated from the decomposition of V‐19 was estimated to be higher than peroxide and methyl free radicals produced in the decomposition of peroxide initiatros. © 1993 John Wiley & Sons, Inc.
Pyrolysis GC/MS studies on plasma‐polymerized pyrrole
Authors: Kojima Takakazu , Takaku Hideaki , Urata Yoshikiyo , Gotoh Kohji
Published: April 2003

Pyrolysis gas chromatography/mass spectrometry and infrared spectrometry have been carried out for plasma‐polymerized pyrrole (PPPy). The major thermal decomposition products have been identified as nitriles with less than four carbons and alkyl pyrroles. Evolution of only monosubstituted alkyl pyrroles, such as 2‐methylpyrrole and 2‐ethylpyrrole, suggests that PPPy consists of monosubstituted pyrrole rings. This is also supported by the result that the IR spectrum of PPPy differs from that of the electrochemically polymerized pyrrole, which consists of disubstituted pyrrole rings. Evolution of linear nitriles shows evidence that a PPPy molecule has the main chain containing nitrogen atoms. The mechanism of polymerization of pyrrole in the discharge is considered to be similar to that of aromatic hydrocarbons, which mechanism involves a process of production of acetylene. © 1993 John Wiley & Sons, Inc.
Thermoanalytical characteristics of durable press treated cotton fabrics
Authors: Trask‐Morrell Brenda J. , Kottes Andrews B. A. , Catalano E. A.
Published: April 2003

Thermoanalytical characteristics of chemically treated cotton fabric often appear similar to those of untreated cotton. The overwhelming amount of cotton cellulose versus the small quantities of finishing chemicals present can mask many features contributed by reactant. The current work is an initial attempt to detect and differentiate among a variety of durable press finishes. They include three N‐methylol reactants, and four polycarboxylic acids with two alkali metal salts of phosphorus‐containing acids used to catalyze their reaction with cellulose. Differential scanning calorimetric and thermogravimetric techniques were employed under dynamic nitrogen conditions. Changes in residue, rate of weight loss, peak intensity, and peak temperature were observed and varied with reactant, catalyst used, and washing. The ability to distinguish among polycarboxylic acids, catalysts, and/or other formaldehyde‐based reactants is of value to the textile chemist. With these preliminary results, we may soon offer a new means of finish identification. © 1993 John Wiley & Sons, Inc.

This article is a US Goverment work and, as such, is in the public domain in the United States of America.
Mechanical and swelling properties of HTPB‐based copolyurethane networks
Authors: Jain S. R. , Sekkar V. , Krishnamurthy V. N.
Published: April 2003

Copolyurethanes of hydroxy terminated polybutadiene (HTPB) and ISRO–Polyol (ISPO), an indigenously developed castor‐oil based polyol, have been prepared using toluene diiso‐cyanate and hexamethylenediisocyanate. The mechanical strength and swelling characteristics of the copolyurethanes cured with trimethylol propane and triethanolamine have been studied to evolve improved solid propellant binders. By varying the ratios of the two hydroxy pre‐polymers, chain extenders, and crosslinkers, copolyurethanes having a wide range of tensile strength and elongation could be obtained. Many of these systems are desirable for their use as propellant binders. The results have been explained in terms of the measured crosslink densities and other swelling properties. © 1993 John Wiley & Sons, Inc.
Studies on sequential interpenetrating polymer network (IPN) based on nitrile rubber and poly(vinyl acetate)
Authors: Patri M. , Samui A. B. , Deb P. C.
Published: April 2003

Several elastomeric sequential interpenetrating polymer networks (IPNs) based on nitrile rubber (NBR) and poly(vinyl acetate) (PVA) have been synthesized. Cross‐linked NBR was swollen in vinyl acetate monomer containing benzoyl peroxide (BPO) as initiator and tetraethylene glycol dimethacrylate (TEGDM) as cross‐linker and then the swollen mass was polymerized. The composition of the IPNs could be varied by varying the swelling time and concentration of BPO and TEGDM. The properties of these IPNs were investigated by tensile test, differential scanning calorimetry (DSC), dynamic mechanical analysis, and swelling measurement. On increasing the PVA content as well as cross‐linking level, the tensile strength increased because of better mixing. DSC showed a single Tg value for all the individual IPNs, the Tg values changing regularly with composition. The tan δ peak for IPNs appeared at higher temperature compared to NBR and was found to be dependent on both the composition of IPNs as well as cross‐linking level. IPNs having 2 and 5% cross‐linker (TEGDM) showed splitting in the tan δ peak. On increasing the cross‐linker concentration to 9% and beyond, the splitting disappeared. The damping capability of the IPNs has been explained in terms of the magnitude of tan δ, area under the tan δ curve, and ½ peak width. The IPNs also showed better solvent‐resistance properties. © 1993 John Wiley & Sons, Inc.
Mechanical properties of honeycomb prepared from aromatic polyimide film
Authors: Ogawa Toshio , Okazaki Noriomi
Published: April 2003

Aromatic polyimides have many advantages such as low thermal expansion coefficient, good electrical insulation, and self‐extinguishing properties. We tried to use polyimide film for honeycomb structure. Polymide honeycomb core and sandwich panel were prepared from polyimide film, i.e., UPILEX R, and adhesive by the expansion method. Mechanical properties, i.e., compressive, crushed, shear, and flexural strengths, were evaluated for this core and panel. Compressive and crushed properties increased largely with the density of the honeycomb, whereas shear and midspan flexural properties did not vary so much with the density, because these failures occured in the adhered interface. Strong adhesion is required for improving the latter properties. © 1993 John Wiley & Sons, Inc.
Fumed silica as stabilizer of precursor emulsions used to prepare polymer latexes
Authors: Hong L. , Ruckenstein E.
Published: April 2003

Introducing small amounts of fumed silica into mixtures of organic liquids, which contain ethylene glycol dimethylacrylate (EGDMA), a hydrocarbon (such as decane), and one of the following monomers: allylchloride (AC), 3,4‐dichloro‐1‐butene (DCB), or methyl methacrylate (MMA), enabled their dispersion into an aqueous solution of surfactant with the generation of stable emulsions. Such emulsions cannot be generated in the absence of fumed silica. Functionalized polymer latexes of poly(AC–EGDMA), poly(DCB‐EGDMA), and poly(MMA–EGDMA) could, thus, be prepared through the polymerization of the emulsions. The chloride units in the poly(AC–EGDMA) or in the poly(DCB–EGDMA) were subsequently converted to quaternary ammonium salts. The resulted polymer‐supported quaternary ammonium salt together with RuCl3, 4‐N‐methylmorpholine N‐oxide (NMO) and ammonium persulfate were employed in the catalytic oxidation of toluene to benzoic acid. Furthermore, the presence of fumed silica in the emulsions enabled the preparation of latexes containing rather uniformly distributed inorganic particle clusters of submicrometer size. Polymer–inorganic blends of NaY zeolite–(SiOx)n/P (MMA–EGDMA), zeolite (4A)–(SiOx)n/P (MMA–EGDMA), TiO2–(SiOx)n/P (MMA–EGDMA), CuO–(SiOx)n/P (MMA–EGDMA), and Cu‐(SiOx)n/P (MMA–EGDMA) were thus obtained. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal application. IX. The dispersing ability of anionic and zwitterionic aniline‐formaldehyde condensates to dyes
Authors: Kuo Ping‐Lin , Wey Bih‐Shiuh , Chen Wen‐Hsiang
Published: April 2003

Anionic and zwitterionic aniline–formaldehyde condensates, N‐(3‐sodium propylsulfonate) aniline–formaldehyde condensates (PSAF), and N, N‐dimethyl‐N‐(3‐propylsulfonate) anilinium–formaldehyde condensates (DPSAF) are used as dispersants to disperse dyes (C. I. Navy Blue 79 and C. I. Brown 1), compared with the conventional dye dispersants–naphthalenesulfonate formaldehyde condensates (NSF). The dispersing properties of the condensates are assessed by the viscosity method, scanning electron microscopy (SEM), the final volume fraction after sedimentation, and adsorption behaviors. Compared to DPSAF, the PSAF and NSF with a lower molecular weight (PSAF‐L, NSF‐L) show significantly lower apparent viscosities of the paste of Navy Blue 79. Comparing the results of the viscosity method with those of SEM and the final volume fraction after sedimentation, it can be concluded that a better‐dispersed paste displayed by SEM shows a lower viscosity and a smaller final volume fraction. The amount of NSF‐L adsorbed on Navy Blue 79 is significantly higher than that of PSAF‐L and DPSAF‐H. However, the sulfonate on PSAF‐L can be extended more deeply toward the bulk phase compared to that on NSF‐L so that PSAF‐L can result in a high effective thickness. These adsorption phenomena are used to interpret the dispersing ability. For Brown 1, the anionic dispersants can reach a similar minimum viscosity independent of their molecular weight, but the PSAF with high molecular weight shows a remarkably low optimum concentration (ca. 3% compared to PSAF‐L 9%, NSFs 5%). © 1993 John Wiley & Sons, Inc.
Assessment of applicability of carreau, ellis, and cross models to the viscosity data of resin solutions
Authors: Raju K. V. S. N. , Krishna D. , Devi G. Rama , Reddy P. J. , Yaseen M.
Published: April 2003

In this study, three popular rheological models, which fit adequately well to viscosity data of polymeric materials, are chosen for making a comparative assessment of their applicability to practical data. The resulting nonlinear equations of the three models are solved by using Levenberg Marquardt's algorithm. The assessment of their applicability to practical viscosity data of 66 solutions of two resins in 11 solvent systems and reported data of other polymers has been analyzed. The Carreau and Ellis models have yielded unique global estimates for various rheological parameters, whereas the Cross model yielded local solutions. However, both Carreau and Cross models yielded parameter estimates with low overall residual error. The three models are found to have good applicability to viscosity data of resin solutions in good and moderate solvents; however, some deviation is observed when they are tested for solvents in which the resin has poor solubility. © 1993 John Wiley & Sons, Inc.
Undoping effect of electropolymerized polymer for two‐layer organic photovoltaic ceils based on polymer/dye junction
Authors: Uehara Kaku , Maekawa Akira
Published: April 2003

The undoping effects of electropolymerized poly(3‐methylthiophene) (PMeT) and poly(N‐methylpyrrole) (PMPy) on the open‐circuit photovoltage Voc and on short‐circuit pho‐tocurrent Jsc were investigated for two‐layer organic photovoltaic cells based on the PMeT or PMPy / vacuumevaporated rhodamine B (RB) under the electrochemical doping level between −3 and +3 V. The value of Voc of the undoped‐polymer / RB cell was larger than that of the doped‐polymer / RB cell. PMeT/RB and PMPy/RB cells gave the minimum value of Jsc at a doping level of 0 V. It was suggested that polarons and bipolarons states formed at a doping level of 0 V may work as a trap site for the carrier to decrease in Jsc. Undoping of the PMeT improved Voc and Jsc of the PMeT/RB two‐layer organic pho‐tovoltaic cell together with its durability. © 1993 John Wiley & Sons, Inc.
Physical characterization of wood and wood‐polymer composites: An update
Authors: Wright J. R. , Mathias L. J.
Published: April 2003

New and reliable test methods have been developed, and are under development, for the physical characterization of wood and whole wood‐polymer composites (WPC is used in this article to refer to polymer‐impregnated whole wood). The methods described here have been designed for smaller samples than are required for most ASTM tests. It should be stressed that, when comparing treated samples to untreated samples in any type of testing, the initial density or specific gravity (density before treatment) of the treated sample should be the same as the untreated control sample. If possible, measurements should be made on a given sample before and after treatment; on a split sample, half should be treated and compared with the untreated half. If there is much variation in density between samples within a group, the effectiveness of the treatment cannot be determined with an acceptable degree of accuracy, since whole wood varies greatly between specimens and density is a major factor contributing to property variability. For example, swelling (due to moisture uptake), modulus, toughness, surface hardness, and compressive strength of wood all increase dramatically with increasing density for both untreated whole wood and WPCs.

Scanning electron microscopy, coupled with x‐ray energy analysis, indicated the presence or absence of good interaction between wood components and in situ formed polymer. For example, poly(EHMA) (the homopolymer of ethyl α‐hydroxymethylacrylate) and wood components were seen to be strongly bonded, and x‐ray activation elemental analysis confirmed the presence of poly(EHMA) and its copolymers within the wood cell walls. On the other hand, proton spin‐lattice relaxation in the rotating frame (T1p) measurements (by 13C solid‐state NMR) for balsa / EHMA WPCs gave two separate sets of relaxation times, one each for unique peaks corresponding to either the polymer or the wood components. It is probable that the region of interaction between poly(EHMA) and the wood component in the balsa / EHMA WPC (the interphase region) is small, as compared to the individual components, and is not observed. This result is consistent with a two‐parameter relaxation process for the peak at ca. 61 ppm, which includes overlapping peaks for the hydroxymethyl carbons of poly(EHMA) and cellulose. © 1993 John Wiley & Sons, Inc.
Polymer optical fiber for near infrared use
Authors: Takezawa Yoshitaka , Ohara Shuichi
Published: April 2003

Using the empirical simulation that we developed to estimate loss spectra of amorphous polymers, we predicted the intrinsic loss spectrum of fluorine‐containing polyarylate (FPAr) that should have a small attenuation loss in the near infrared region. Loss of FPAr is smaller than that of poly (methyl methacrylate), which is a typical optical polymer used as a core material in polymer optical fiber (POF), above 720 nm. FPAr was synthesized by phase transfer catalyzed polycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane with isophthaloyl dichloride. Its glass‐transition temperature (Tg) by DSC is 163°C. This indicates that FPAr has higher heat resistance than polycarbonate (PC) by about 10°C. A film of 100μm thick has over 85% transmittance from 330 to 900 nm. Values from a tension test are similar to those of PC. As a result, FPAr is expected to be a good core polymer for POF, because of its highTg, good transparency, and good flexibility. Next, the POF made of FPAr was fabricated by a melt‐flow spinning method. It had larger attenuation loss than predicted. The difference from the simulation was extrinsic loss caused by the fabricating process. Therefore, when a more suitable fabricating process is developed, loss of FPAr‐POF can be decreased, so that it will be applicable to optical communications in the near infrared region. © 1993 John Wiley & Sons, Inc.
Effect of some sodium bisulfite adducts of different chain lengths on the course of the emulsion polymerization of vinyl acetate
Authors: Badran A. S. , Ramadan A. M. , Moustafa A. B. , Shaffel K. A.
Published: April 2003

The emulsion polymerization of vinyl acetate using some bisulfite adducts of different chain lengths with potassium persulfate as the redox initiation system, in the absence of emulsifier, was studied. The effects of such adducts, which contain the same weight equivalent of bisulfite anion, on the rate of polymerization, maximum conversion, and stability of the produced polymer lattices as well as the morphological characteristics including volume‐average diameters and the number of polymer particles per unit volume of water were investigated. The rate of polymerization was found to be dependent on the concentration of benzaldehyde, acetaldehyde, octyl aldehyde, methyl propyl ketone, and acetone sodium bisulfite adducts to the powers 0.54, 0.66, 0.95, 1.0, and 1.1, respectively. Also, it was found that increasing adduct chain lengths decreases the volume‐average diameter, increases the obtained lattice stability, and improves the morphology of the polymeric particles, where a spherical morphology and extra stability were obtained in the presence of the octyl aldehyde adduct. © 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.
The application of infrared microimaging for the determination of the distribution, penetration depth, and diffusion profile of methyl centralite and dibutyl phthalate deterrents in nitrocellulose monoperforated propellant
Authors: Louden J. D. , Duncan I. A. , Kelly J. , Speirs R. M.
Published: April 2003

Infrared microspectroscopy was used to determine quantitatively and qualitatively methyl centralite (MC) and dibutyl phthalate (DBP) diffusion profiles in cross sections of nitro‐cellulose‐based monoperforated propellant grains. The absorbance values of the CO peak of DBP at 1717 cm −1 and the aromatic CC peak of MC at 1496 cm −1 were measured relative to the NO2 overtone peak of the nitrocellulose at 2555 cm−1 at 10 μm intervals from the outside edge inward (external profile) and the perforation edge inward (internal profile). Infrared microimaging was used to determine the distribution and penetration depth of the DBP and MC using the CO peak of DBP at 1717 cm−1 and the aromatic CC peak of MC at 1496 cm−1 as diagnostic of the two deterrents to obtain the contour and axonometric displays of the distribution. © 1993 John Wiley & Sons, Inc.
Synthetic pulp fiber ozonation: An ESCA and FTIR study
Authors: Chtourou H. , Riedl B. , Kokta B. V. , Adnot A. , Kaliaguine S.
Published: April 2003

Polytheylen (PE) pulp fiber was treated by ozone for surface modification. Surface analysis was performed by using X‐ray photoelectron (ESCA) and IR (FTIR) spectroscopies. Carbon (C) and Oxygen (O) were the main atoms detected by ESCA (C1s, O1sregions) on the treated fiber. Analysis of the C1speaks (C1, C2, and C3) showed that the oxidation level changed with the ozonation time. O1speak components (O0, O1, and O2) were very useful to complete the surface analysis. FTIR spectra showed the presence of carbonyl groups (1740–1700 cm−1), even on nontreated fiber, which increased in intensity as treatment time increased. Ozone treatment went beyond the surface level to the bulk of the fiber. This was marked by a large increased of the intensity of the carbonyl band after 3 h of ozonation. Thermal analysis suggests structure and morphology changes of fiber when exceeding 2 h of ozonation. © 1993 John Wiley & Sons, Inc.
Hydrogenation of epoxidized natural rubber
Authors: Roy Sanjoy , Bhattacharjee S. , Gupta B. R.
Published: April 2003

The thermal properties of epoxidized natural rubber (ENR) have been found to improve upon hydrogenation in a solution phase, in the presence of a homogeneous catalyst, at 50°C. The hydrogenated ENR shows higher Tmax values in the DTG scan and, upon aging, the change in carbonyl concentration is less as compared to that of ENR, as detected by IR spectrophotometry. The hydrogenated product was characterized by IR and 1H–NMR spectroscopy. © 1993 John Wiley & Sons, Inc.
Thermotropic liquid crystalline copolyesters. I. Synthesis and thermal characterization of the copolyesters of terephthaloyl chloride, hydroquinone, and 1,4‐butane diol
Authors: Rath Asoke K. , Ponrathnam Surendra
Published: April 2003

A new series of random thermotropic liquid crystalline polyesters (LCPs) was synthesized from terephthaloyl chloride, hydroquinone, and 1,4‐butane diol. The copolyester composition was varied by changing the relative mole ratio of hydroquinone and 1, 4‐butane diol in the feed. All the copolyesters displayed thermotropic liquid crystallinity at relatively low temperatures. Liquid crystalline behavior of the copolyesters has been characterized by polarizing light microscopy and by differential scanning calorimetry (DSC). The effect of co‐polyester composition on the temperature and thermodynamic parameters related to liquid crystalline transition is discussed. © 1993 John Wiley & Sons, Inc.
Flexural and impact properties of high‐density polyethylene/linear low‐density polythylene blend
Authors: Gupta A. K. , Rana S. K. , Deopura B. L.
Published: April 2003

In this article, a study of flexural and impact properties of binary blends of high‐density polyethylene (HDPE) and linear low‐density polyethylene (LLDPE), over a full range of blending ratios, is presented. The property distinctions in the three ranges of composition (viz., HDPE‐rich blend, LLDPE‐rich blend, and the middle region) are remarkable and consistent with the different effects of cocrystallization in the respective concentration ranges. Furthermore, the analysis of flexural yield properties data, in terms of the Ree‐Eyring equation, and the correlation of results with variation of x‐ray crystallinity are presented, which suggests the existence of two types (i.e., mobile and immobile) of segments in the amorphous phase of the blend. The relative variation of these two types of amorphous phase in the three different composition ranges of the blend are discussed. The impact strength variation of this blend is also found to correlate with the variation of the fraction of amorphous phase in the blend. © 1993 John Wiley & Sons, Inc.
Batch polymerization of methyl methacrylate in mini/macroemulsions
Authors: Fontenot K. , Schork F. J.
Published: April 2003

The kinetics of the isothermal batch macroemulsion and miniemulsion polymerizations of methyl methacrylate (MMA) at 50°C have been studied. Hexadecane was used as the cosurfactant or swelling agent. The nucleation mechanisms were observed to be different between macroemulsions and miniemulsions. The effect of surfactant, cosurfactant, initiator, shear, and hold time on droplet nucleation was studied. The miniemulsion particles were found to contain more radicals on average than the macroemulsion particles using certain recipes. This resulted in higher polymerization rates for the miniemulsions at identical particle numbers. The latex‐particle‐size distributions were similar even though the mini‐emulsion droplets start out with a high polydispersity of around 1.5. Miniemulsion latexes were found to be more stable under shear. Conductance of emulsions during polymerization was found to be a valuable on‐line tool for investigating particle nucleation and growth. © 1993 John Wiley & Sons, Inc.
Contribution of adsorptive or acid–base interaction between phenol molecules and polyvinylpyridine membrane to the large permeability of phenol through the membrane
Authors: Uramoto Hiromu , Kawabata Nariyoshi
Published: April 2003

Permeability of phenol from aqueous solution to organic solvent through a microporous membrane made of cross‐linked poly (4‐vinylpyridine) (polyvinylpyridine membrane) was about 12 times larger than that through a microporous membrane made of polyethylene (polyethylene membrane) having similar thickness, porosity, and mean pore diameter with those of polyvinylpyridine membrane. Adsorptive or acid–base interaction between phenol molecules and polyvinylpyridine membrane was shown to play an important role in this unusally rapid permeation of phenol through the membrane. The amount of phenol contained in polyethylene membrane per unit volume of the pores was about six times larger than the phenol concentration in the feed aqueous solution. However, the amount of phenol contained in polyvinylpridine membrane per unit volume of the pores was 80–260 times larger than the feed phase concentration. The rapid permeation of phenol through poly‐vinylpyridine membrane was thus explained in terms of the extensive enrichment of phenol in the membrane due to the adsorptive or acid–base interaction between phenol molecules and the membrane. © 1993 John Wiley & Sons, Inc.
Bridging the PE lifetime under fatigue and creep conditions with its crystallization behavior
Authors: Kadota K. , Chum S. , Chudnovsky A.
Published: April 2003

The service lifetime for several linear polyethylene copolymers was studied by fatigue‐type accelerated tests. The material morphology and crystallization behavior were correlated with the lifetime and the failure modes. The correlation is based on the rate constant of material degradation (RCMD) recently introduced by the authors within a mathematical model for crack layer growth kinetics. RCMD is found to depend on the loading conditions (e.g., creep or fatigue) and on material morphology reflected in crystallization kinetics. The ratio of RCMDs for fatigue and creep is a scaling factor that allows one to correlate fatigue and creep lifetimes. The dependence of the RCMD's ratio on the morphological features associated with the primary and secondary crystallization kinetics is also reported in this paper. © 1993 John Wiley & Sons, Inc.
An evaluation of the DAWN‐B light scattering unit from wyatt technology: Suggested calibration, normalization, and clarification procedures
Authors: Yunan Wan , Zhongde Xu , Li Jianbo , Rosenblum William M. , Mays Jimmy W.
Published: April 2003

Proper normalization, calibration, and sample clarification procedures for use with the Wyatt Technology DAWN‐B laser light scattering photometer are described. The utility of the proposed methods is confirmed by comparing results obtained on the solution properties of polystyrene standards in three different solvents (toluene, tetrahydrofuran, and methyl ethyl ketone) with results from the literature and generated using a Chromatix KMX‐6 low‐angle light scattering photometer. © 1993 John Wiley & Sons, Inc.
Surface graft polymerization onto silicone
Authors: Iwata Hiroo , Isozaki Shuji
Published: April 2003

A method was developed for surface graft polymerization onto silicone. A silicone prepolymer carrying vinyl groups, which can be cured by a free‐radical mechanism, was used. Acrylamide can be easily graft polymerized by simply heating the films made of a mixture of the silicone prepolymer and peroxide in an acrylamide monomer solution using an autoclave. Any complicated procedures, such as thorough degassing of the silicone films and the monomer solution, and sealing them into a glass ampoule, are not necessary. The grafted layer uniformly covered the silicone surface. The surface properties of the silicone become hydrophilic and slippery after grafting of the poly(acrylamide). © 1993 John Wiley & Sons, Inc.
Instrumented izod impact testing
Authors: Slavin S. E. , Beswick G. T.
Published: April 2003

The notched Izod impact test is the most prevalent technique used to characterize the effects of high‐impulse loads on polymeric materials. In order to extract ancillary information concerning fracture properties in addition to the total fracture energy, an instrumented version of this test is examined. Oscillations in the load signal, which severely degraded the utility of the data for materials fracturing in a brittle manner, are determined to be the result of specimen vibration caused by the impact of the hammer. Placement of a felt cushion on the face of the hammer is shown to eliminate these oscillations and the effects of the felt on the load‐time information are shown to be minimal. Finally, peak load data extracted from instrumented Izod tests employing felt padding, is used to determine the stress‐intensity factor for several plastics of commercial interest. © 1993 John Wiley & Sons, Inc.
Polymerization blending for compatible poly(ether sulfone)/aramid blend based on polycondensation of an N‐silylated aromatic diamine with an aromatic diacid chloride in poly(ether sulfone) solution
Authors: Hayashi Hideo , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

Poly(ether sulfone) (PES) and poly[N,N′‐(oxydi‐p‐phenylene)isophthalamide] (44I) were blended readily by the polymerization‐blending method; i.e., N,N′‐bis(trimethylsilyl)‐substituted bis(4‐aminophenyl) ether was reacted with isophthaloyl chloride in the PES solution in DMAc, and the resulting mixture was directly cast into films. The procedure afforded transparent films over the entire PES/44I composition range. Homogeneous mixing of the component polymers in the form of films was shown by a single glass transition temperature, whereas a conventional solution‐blending method afforded less compatible films in the PES‐rich composition. This was also supported by morphological and infrared studies. The mechanical properties of the blend films, particularly the elongation‐at‐break, were improved by using the polymerization‐blending method. © 1993 John Wiley & Sons, Inc.
Sorption of water in nylon 6‐clay hybrid
Authors: Kojima Yoshitsugu , Usuki Arimitsu , Kawasumi Masaya , Okada Akane , Kurauchi Toshio , Kamigaito Osami
Published: April 2003

Various nylon 6‐clay hybrids, such as molecular composites of nylon 6 and silicate layers of montmorillonite and saponite, NCHs and NCHPs, respectively, have been synthesized. Sorption of water in those hybrids was measured to estimate the resistance to water permeation. The diffusion coefficient D and the partition coefficient K were obtained from the sorption curves. The resistance to water permeation of NCH was superior to that of nylon 6 because of a decrease in D. In NCHP, saponite had a smaller effect on the increase of the resistance. The diffusion coefficients in NCH and NCHP decreased with an increase in the amount of clay minerals. It was found that those diffusion coefficients were well described by the contribution of the constrained region calculated from the storage and the loss modulus at the glass transition temperature. According to the mixing law, the following equation was obtained between the diffusion coefficient D and the fraction of the constrained region C, D = Da(1 – C)1/n, where the values of Da (diffusion coefficient in amorphous nylon 6) and n (morphology parameter) were 12.6 X 10−7cm2/s and 0.585, respectively. © 1993 John Wiley & Sons, Inc.
Polymer crystallization kinetics: Poly(ethylene terephthalate) and poly(phenylene sulfide)
Authors: Ravindranath K. , Jog J. P.
Published: April 2003

Analysis of isothermal crystallization data of PET and PPS was carried out using Avrami and Tobin models. The models gave fractional values of exponent n and the standard deviation varied between 1 and 4%. No improvement in the standard deviation could be obtained even after incorporating the nucleation rate in these models. The Hillier model gave a good fit only to the isothermal crystallization data of PET. A simple model considering primary and secondary crystallization has been proposed. The model is verified using isothermal crystallization data of PPS. © 1993 John Wiley & Sons, Inc.
Oriented PP‐PS composites obtained by polymerization of styrene inside oriented PP matrices. I. Dispersion of PS and the composites' orientation
Authors: Trznadel M. , Pluta M. , Kryszewski M.
Published: April 2003

Dispersion of polystyrene (PS) and the molecular orientation of the polypropylene–polystyrene (PP–PS) composites acquired by the in situ polymerization of styrene in the oriented PP matrices were characterized by microscopic observations, birefringence measurements, and differential scanning calorimetry. It has been shown that applied processing of the “envelope” polymerization leads to obtaining oriented composites with large contents and the specific dispersion of PS. Some composites exhibit a substantial gradient of PS concentration and a gradient of molecular orientation, both strongly dependent on the initial structure of the oriented PP matrix. The modification of the PP structure taking place during processing does not disturb the orientation of the matrices deformed to the higher draw ratios. The structural changes of the oriented PP induced by processing are reflected in the shrinkage behavior and mechanical properties discussed in the second part of this paper. © 1993 John Wiley & Sons, Inc.
Rheological behavior of short carbon fiber‐filled thermoplastic elastomer based on styrene–isoprene–styrene block copolymer
Authors: Roy D. , Gupta B. R.
Published: April 2003

The rheological behavior of styrene–isoprene–styrene block copolymer filled with short carbon fibers has been studied with the Monsanto Processability Tester (MPT). Carbon fibers of 6 mm length were used in the range of 0–20 phr. The rheological studies were carried out in the temperature range of 150–180°C and the shear rate range of 50.6–401.2 s−1 using three different capillaries with varying L/D ratio. The die swell was automatically recorded using a laser scanning system attached to the MPT. The results show that the composites behave as pseudoplastic materials and follow the power‐law model. The shear viscosity of the composites decreases up to 10 phr fiber loading and then either increases or remains constant with further increase of fiber concentration. The die swell decreases with increase of fiber loading and L/D ratio of the capillary. © 1993 John Wiley & Sons, Inc.
Surface modification of polyethylene and polypropylene by ion implantation
Authors: Švorčík V. , Rybka V. , EndrŠt R. , Hnatowicz V. , Kvítek J. , Seidl P.
Published: April 2003

The creation of oxidized structures and double bonds in polyethylene (PE) and polypropylene (PP) samples implanted with P+ ions was studied. The surface polarity and the electrical conductivity of the ion‐implanted polymers were also examined. As a result of the ion implantation, the polymer macromolecules are broken up and the material is degraded. An oxygen penetration into the radiation‐damaged polymers is also observed, with PE being more vulnerable to the oxidation. The ion‐implanted PP exhibits higher surface polarity and sheet conductivity compared to that of PE. © 1993 John Wiley & Sons, Inc.
Anionic polyurethane ionomer for one‐step electrosynthesis of conductive composites
Authors: Robila Gabriela , Ivǎnoiu Maria , Buruiana Tinca , Buruiana E. C.
Published: April 2003

A water soluble ionomer with natrium propanesulfonate groups was prepared based on a linear polyurethane with high content of NHCOO structures. This compound was used both as macromolecular electrolyte and dopant ion in electrochemical polymerization of pyrrole, obtaining a molecular level polypyrrole‐propanesulfonate polyurethane composite with electroconductive properties. © 1993 John Wiley & Sons, Inc.
Lipoprotein lipase immobilization onto porous polyvinyl alcohol beads
Authors: Hayashi Toshio , Hyon Soung‐Hyu , Cha Won‐Ill , Ikada Yoshito
Published: April 2003

Water‐insoluble proteases were prepared by immobilizing lipoprotein lipase (LPL) onto the surface of porous polyvinyl alcohol (PVA) beads by covalent fixation. The relative activity of the immobilized proteases was found to remain high toward small ester substrates, p‐nitrophenyl laurate (pNPL). The relative activity of the immobilized LPL by cyanogen bromide (CNBr) method decreased gradually with the decreasing surface concentration of the immobilized LPL on the porous PVA beads. On the contrary, the immobilized LPL by hexamethylene diisocyante (HMDI) method gave an almost constant activity for the substrate hydrolysis within the surface concentration region studied and gave higher relative activity (RA) than that by the CNBr method. The Michaelis constant, Km, and the maximum reaction velocity, Vm, were estimated for the free and the immobilized LPL. The apparent Km was larger for the immobilized LPL than for the free one, and Vm was smaller for the immobilized LPL. The pH, thermal, and storage stabilities of the immobilized LPL were higher than those of the free ones. The initial enzymic activity of the immobilized LPL maintained almost unchanged without any leakage and inactivation of LPL when the batch enzymic reaction was performed repeatedly, indicating excellent durability of the immobilized LPL. © 1993 John Wiley & Sons, Inc.
Tensile strain rate effect in mechanical properties of dummy HTPB propellants
Authors: Chung H. L. , Kawata K. , Itabashi M.
Published: April 2003

The tensile strain rate effect in tensile strength and elongation at break for a series of filled dummy hydroxy‐terminated polybutadiene (HTPB) propellant binders was studied. The data were obtained at various tensile strain rates from 10−4 to 10−1 s−1 on two types of specimens at room temperature. The “high velocity ductility” behaviour, which is qualitatively similar to those of unfilled elastomers, was revealed. This means that the breaking strain increases markedly at elevated strain rates. For “Bukkon‐type” and rod‐shaped specimens, test results are consistent with each other. The fact that the increased filled solids level leads to a decreased breaking elongation capability and an increased tensile strength was obviously found. © 1993 John Wiley & Sons, Inc.
Relaxations of bisphenol A‐based epoxides cured with aliphatic diamines
Authors: Matsukawa Mami , Okabe Hirotaka , Matsushige Kazumi
Published: April 2003

The main α and sub β relaxations in bisphenol A‐based epoxides cured by two kinds of aliphatic diamines were examined in wide temperature and frequency ranges by using middle‐frequency dynamic, dielectric, and ultrasonic measuring systems. The obtained temperature–frequency correlation maps revealed an Arrhenius‐type behavior for the β relaxation with apparent activation energy of 16 kcal/mol. For the α relaxation, the maps were in good agreement with the W.L.F. equation. Owing to the similarity of structure in these resins, both maps showed the same tendencies. © 1993 John Wiley & Sons, Inc.
The removal of color from effluents using polyamide–epichlorohydrin‐cellulose polymer. III. Use in anionic dye removal in a batch process
Authors: Hwang M. C. , Chen K. M.
Published: April 2003

Polyamide–epichlorohydrin–cellulose (PAE–Cell) can adsorb substantial quantities of several direct dyes and acid dyes from aqueous solutions using a batch process. The ad‐sorption kinetics of these dyes on PAE–Cell was studied using Langmuir and Freundlich isotherm equations at different temperatures. Other adsorption parameters studied were initial dye concentration, the pH of the solution, particle size, treated time, and salt added. The PAE–Cell was found to have monolayer equilibrium saturation capacities of more than 500 mg dye per PAE–Cell for these anionic dyes. These results show that PAE–Cell polymers exhibit better capacity than do some types of commercial activated carbon. © 1993 John Wiley & Sons, Inc.
The development of a mathematical model for the pultrusion of blocked polyurethane composites
Authors: Ma Chen‐Chi M. , Chen Chin‐Hsing
Published: April 2003

The thermokinetic behavior of blocked polyurethane‐based composites during the pultrusion of glass‐fiber reinforced composites is investigated utilizing a mathematical model accounting for the heat transfer and the heat generation during curing. The equations of continuity and energy balance, coupled with a kinetic expression for the curing system, are solved using a finite difference method to calculate the temperature and conversion profiles in the thickness direction in a rectangular pultrusion die. A kinetic model, dP/ dt = A exp(−E/RT) (1−P)nPm, was proposed to describe the curing behavior of a blocked polyurethane resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry (DSC) scans using a multiple regression technique, which was able to predict the effects of processing variables on the pultrusion. The effects of process variables (e.g., pulling rate, die temperature, and die thickness) on the performance of the pultrusion are also evaluated. © 1993 John Wiley & Sons, Inc.
Structural analysis of methyl methacrylate‐grafted silk fibers
Authors: Tsukada Masuhiro , Kasai Nobutami , Freddi Giuliano
Published: April 2003

The structural changes of silk fibers grafted with methyl methacrylate (MMA) were investigated in relation to the weight gain. Both the refractive indices, parallel and perpendicular to the fiber axis, decreased with increasing weight gain, although the former showed a step drop in the weight gain range of 0–30%. Accordingly, birefringence and the isotropic refractive index also decreased, suggesting a lower degree of molecular orientation and crystallinity of MMA‐grafted silk fibers. However, X‐ray diffraction curves demonstrated that the crystalline structure remained unchanged, regardless of MMA grafting, implying that the MMA polymer attached preferentially within the amorphous regions of the fiber. Tensile strength and elongation at break of the grafted silk fibers, measured in dry and wet states, gradually decreased over the weight gain range examined. MMA‐grafted silk fibers in wet state exhibited comparatively lower values of strength and elongation, though the hydrophobicity, induced by the grafted polymer, resulted in an attenuation of the differences, especially at high weight gains. TMA analysis demonstrated that the onset temperature of the final extension shifted to a higher value, in the weight gain range 30–50% Dynamic mechanical measurements showed that the thermally induced molecular movement of MMA‐grafted silk increased, as illustrated by the trend of both dynamic storage and loss modulus curves. © 1993 John Wiley & Sons, Inc.
Bacterial cellulose membrane as separation medium
Authors: Shibazaki Hideki , Kuga Shigenori , Onabe Fumihiko , Usuda Makoto
Published: April 2003

A thin membrane of bacterial cellulose (BC) obtained fromAcetobacterculture was tested for its performance as a dialysis membrane in aqueous systems. The BC membrane showed superior mechanical strength to that of a dialysis‐grade regenerated cellulose membrane, allowing the use of a thinner membrane than the latter. As a result, the BC membrane gave higher permeation rates for poly(ethylene glycols) as probe solutes. The cutoff molecular weight of the original BC membrane, significantly greater than that of regenerated cellulose, could be modified by concentrated alkali treatments of the membrane. The nature of the change at the ultrastructural level caused by the alkali treatments was studied by X‐ray diffraction and scanning electron microscopy. © 1993 John Wiley & Sons, Inc.
Reaction mechanisms, microstructure, and fracture properties of thermoplastic polysulfone‐modified epoxy resin
Authors: Min B.‐G. , Hodgkin J. H. , Stachurski Z. H.
Published: April 2003

The microstructure and fracture properties of diglycidyl ether of bisphenol A (DGEBA) epoxy resins modified with phenolic hydroxyl‐terminated polysulfone (PSF) and cured with diaminodiphenyl sulfone (DDS) hardener have been investigated as a function of the molecular weight and concentration of PSF. The microstructure changed from a typical particulate structure to a phase‐inverted structure as the molecular weight and/or the concentration of the modifier increased. The fracture toughness, measured by compact tension tests, increased with the microstructural changes toward the phase‐inverted structure. The microstructural changes observed have been interpreted in terms of variation in the reaction mechanisms as determined by near‐infrared spectroscopy. The level of minor reactions such as etherification and homopolymerization reactions increased with increasing molecular weight and/or concentration of the modifier, in line with the tendencies observed in microstructure and fracture toughness. In the system containing 20 wt% of Mn 10,000 PSF, about 30% of the epoxy groups were consumed by etherification and homopolymerization reactions, whereas none of these reactions occurred in the unmodified system. The increase in minor reactions in the modified systems may be to be due to the restricted molecular mobility, resulting from the increase of system viscosity caused by the modification. This increase in viscosity also reduced the rate of phase separation. The degree of heterogeneity in the epoxy network must increase with the increasing side reactions. The formation of the heterogeneous epoxy network and the slowdown of phase separation will prevent a uniform precipitation of the modifier and finally result in a heterogeneous partially phase‐inverted structure or the completely phase‐inverted structure, depending on the amount of modifier incorporated over the critical concentration. © 1993 John Wiley & Sons, Inc.