bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of 4‐hydroxy‐2,3,5,6‐tetrabromobenzyl phosphonates and effects of their flame retardance on impact polystyrene
Authors: Yang Chin‐Ping , Lee Tain‐Wen
Published: April 2003

p‐Cresol was converted into 2,3,5,6‐tetrabromocresol by AlCl3 catalyst bromination, and then further brominated to 4‐hydroxy‐2,3,5,6‐tetrabromobenzyl bromide (HTBBB) in benzene by light. HTBBB reacted easily with trialkyl phosphite to produce 4‐hydroxy‐2,3,5,6‐tetrabromobenzyl phosphonates (HTBBPs) in solvents. Although the reaction of HTBBB with triaryl phosphite was slower than that with trialkyl phosphite, it does produce corresponding phosphonate with ease. Except for DMF, DMAc, chloroform, and tetrahydrofuran, HTBBP was difficult to dissolve in ordinary organic solvents. Of all the synthesized HTBBP, dimethyl hydroxy‐2,3,5,6‐tetrabromobenzyl phosphonate showed the poorest solubility. With the addition of these new compounds containing bromine and phosphorus atoms to HIPS as flame retardants, the results of oxygen index measurement showed that the flame resistance of these compounds was greater than the additive effect of the two corresponding individual brominated compound and phosphorus‐containing compound. It means that these new compounds seem to act synergistically as flame retardants in HIPS. Simultaneous addition of bominated compound and phosphorus‐containing compound to HIPS ends up with a similar effect as mentioned above, but the new compounds can prevent the exclusion of phosphorus‐containing compound from polymer matrix.
Determination of the molecular weight between cross‐links of elastomeric stocks by tensile retraction measurements I. SBR vulcanizates
Authors: Hergenrother W. L.
Published: April 2003

Tensile retraction measurements were used to determine the effective molecular weight between cross‐links of vulcanized SBR rubbers. The procedure has proven to be a rapid, precise, and reproducible method of obtaining the total number of effective cross‐links present in an unperturbed elastomer. Since the only data needed besides stress‐strain curves were the sample density and the volume fraction of filler present, questionable evaluation of unknown constants was avoided. In addition, an indication of the interactions between the polymer and filler can be studied. Such a relationship with hydrocarbon rubbers appears to give information that will directly relate to end use applications.
Surface coatings based on water‐soluble epoxy allyl ether polymer systems
Authors: Krishnamurti N. , Shirsalkar M. M. , Sivasamban M. A.
Published: April 2003

Water‐soluble polymers based on epoxy esters modified by partial allyl ethers of various polyhydric alcohols were prepared. These have very good hydrolytic and storage stability. The paints prepared from them performed well as primers and also exhibited moderate gloss. The effect of using melamine resin as external cross linker was also studied.
Depolymerization of poly(fluoroalkyl methacrylate‐co‐methyl methacrylate) as studied with thermogravimetry
Authors: Hayakawa Kiyoshi , Kawase Kaoru , Yamakita Hiromi , Taoda Hiroshi
Published: April 2003

Thermal behaviors of a few kinds of poly(fluoroalkyl methacrylate‐co‐methyl methacrylate) prepared by γ‐ray copolymerization were investigated by using thermogravimetric measurements together with the intermittent analysis of the gaseous products. The thermal degradation of copolymers composed of one of fluoroalkyl methacrylates of the following structures: CH2C(CH3)COOCH2(CF2CF2)nH, where n = 1,2, and 3, and methyl methacrylate proceeded according to the depolymerization mechanism reproducing the pristine component comonomers exclusively, but their thermograms in inert atmosphere showed the feature of a two‐step reaction. In air, however, thermograms of copolymers did not show such a stepwise decrease in weight with the elevating temperature, and temperatures at which depolymerization was introduced shifted to a much higher region. The overall aspects of depolymerization of copolymers seemed to be much similar to that of fluoroalkyl methacrylate homopolymer previously reported, and the retardation of depolymerization by air was considered to be due mainly to the stabilization of once‐formed polymer radicals by oxygen.
Stress relaxation of some linear aliphatic nylons
Authors: Yeung Mary W.‐Y. , Williams H. Leverne
Published: April 2003

The stress relaxations of unoriented nylons 4, 6, 11, 12, 66, 610, 612, and 666 were measured and compared over a temperature range from 25 to 180°C. Samples were tested after conditioning to 0, 50, and 100% relative humidity. The effect of crystallinity was indicated by the use of annealed samples prepared at 0% relative humidity.
Cure kinetics of epoxy resins and aromatic diamines
Authors: Moroni Antonio , Mijovic Jovan , Pearce Eli M. , Foun Cheu Ching
Published: April 2003

An analysis of the cure kinetics of several different formulations composed of bifunctional epoxy resins and aromatic diamines was performed. A series of isothermal differential scanning calorimetry (DSC) runs (at higher temperature) and Fourier transform infrared spectroscopy (FT‐IR) runs (at lower temperature) provided information about the kinetics of cure in the temperature range 18–160°C. All kinetic parameters of the curing reaction, including the reaction rate order, activation energy, and frequency factor were calculated and reported. Dynamic and isothermal DSC yielded different results. An explanation was offered in terms of different curing mechanisms which prevail under different curing conditions. A mechanism scheme was proposed to account for various possible reactions during cure.
Correlations of the first normal stress difference with shear stress and of the storage modulus with loss modulus for homopolymers
Authors: Han Chang Dae , Jhon Myung S.
Published: April 2003

The effects of temperature, molecular weight and its distribution, side chain branching, and the structure of polymers on the elastic behavior of bulk homopolymers were investigated, by using logarithmic plots of first normal stress difference (N1) against shear stress (σ12) and logarithmic plots of storage modulus (G′) against loss modulus (G″). For the investigation, we have used data from the literature as well as our recent experimental results, covering a very wide range of temperature and shear stress or loss modulus. It has been found that such plots are very weakly sensitive to (or virtually independent of) temperature and to the molecular weight of high molecular weight polymers, but strongly dependent upon the molecular weight distribution and the degree of side chain branching. A theoretical interpretation of the observed correlations is presented, using molecular theories.
Thermal effects in polytetrafluoroethylene at high hydrostatic pressures
Authors: Rodriguez Ernesto L.
Published: April 2003

The temperature changes as a result of rapid hydrostatic pressure applications are reported for polytetrafluroethylene (PTFE, Teflon) in the reference temperature range from 294° to 381°K and in the pressure range from 13.8 to 200 MN/m2. The thermal effects were found to be higher at the reference temperature approximating the transition temperatures of 19° and 30°C than at higher reference temperature. The data were analyzed by determining the predicted thermoelastic coefficients derived from the Thomson equation (∂T/∂P = αT/ρCp). A curvefitting analysis showed that the empirical curve, (∂T/∂P) = ab(ΔP)b−1, described the experimental thermoelastic coefficients obtained from the experiments. The fact that no agreement was found between the predicted and the experimental coefficients is due to the physical changes in PTFE at the transition temperatures. The relationship between the thermal effects and the chain molecular motion is discussed by including dynamic mechanical analysis and differential scanning calorimetry DSC measurements for the PTFE samples.
Regression analysis studies of polymer transitions II. TII from specific heat and other data for polyisobutylene
Authors: Boyer Raymond F. , Enns John B.
Published: April 2003

Linear regression analysis studies with residuals of heat capacity vs. temperature (Cp vs. T) data above the glass transition temperature (Tg) for polyisobutylene (PIB) of molecular weights M¯v = 1,350,000 and M = 4900 show that the data points can be represented by three straight lines in each case. The lower intersection temperature represents the intermolecular Tll transition (relaxation); the upper one an intramolecular Tlp process. Both processes are confirmed by ultrasonic velocity data in vulcanized butyl rubber, by zero shear melt viscosity data in PIB (M = 4900); and by isothermal specific volume vs. pressure data in PIB (M¯v = 36,000). Tll is confirmed by thermal diffusivity, differential scanning calorimetry (DSC), 13C nuclear magnetic resonance (NMR) spectroscopy and the T* temperature of Lobanov and Frenkel based on Arrhenius‐type plots log frequency vs. 1/Tg. A comparison of dynamic mechanical loss data, both old and new, reveal that Tll follows a Vogel‐WLF type relation; log f vs. 1/(T0 −1/To). PIB samples with number average molecular weights between 7100 to 860,000 have been measured on three types of support systems: glass braid (0.3 Hz), filter paper (11 Hz), brass shim stock (14–16 Hz), and give similar values of Tu. A considerable amount of literature data long neglected from the viewpoint of its bearing on Tll is reviewed. Tll has been observed in the same way as Tg by both relaxational and quasi‐static methods. Some instructive cross comparisons between these two types of methods emerge. With so many diverse methods yielding evidence for Tll in PIB, it cannot be dismissed as an artifact. A molecular origin for Tll is plausible in terms of the Frenkel‐Baranov phase dualism mechanism. A complete relaxation map (log f vs. 1/T) has been assembled with frequencies from 10−2 to 1010 Hz and temperatures from 150 to 500 K. It shows Tβ, Tg, Tll and methyl group rotation, all based on data in the literature. The molecular weight dependence to Tg and Tll and the low resiliency of butyl rubber as it relates to Tll are discussed in the appendices.
Poly(P‐benzoquinono)diimidazoles from two‐ring aromatic dicarboxylic acids
Authors: Sideridou‐Karayannidou I.
Published: April 2003

New poly(p‐benzoquinono)diimidazoles have been synthesized by one‐stage polycondensation in polyphosphoric acid of 2,3,5,6‐tetraamino‐p‐benzoquinone with diphenyl‐4,4′‐dicarboxylic acid, diphenylmethane‐4,4′‐dicarboxylic acid, 4,4′‐oxydibenzoic acid, and 4,4′‐sulfonyldibenzoic acid. The polymers were characterized by infrared and ultraviolet spectral study, viscometric measurements, and thermal analysis. The effects of introducing flexibilizing links such as CH2,O, and SO2 in the backbone of the polymers, on their thermal stability and solubility were studied.
The influence of annealing on the thermal properties of poly(ethylene terephthalate) fibers II. The thermal volume expansivity of annealed pet fibers
Authors: Urbanczyk G. W. , Michalak G.
Published: April 2003

The influence of annealing of PET fibers on their thermal volume expansivity has been examined. The annealing has been performed in air in the loose state of the fibers within the temperature range 130–210°C for 2,5,10, and 30 min. The established volume expansivity coefficients α25 give rise to the conclusion that three temperature intervals of annealing may be distinguished. The ascertained variation in α25 has been discussed on the basis of established morphological and fine structure changes caused in the fibers by the applied annealing.
Tertiary aromatic amines as cure reaction promoters for unsaturated polyester resins. II. Low temperature studies
Authors: Storey Robson F. , Sudhakar Dantiki , Hogue Melissa
Published: April 2003

N,N‐dimethyl‐p‐toludine (DMPT), N,N‐dimethyl‐m‐toluidine (DMMT), and their isomeric blends, were compared to N,N‐dimethylaniline (DMA) as cure reaction promoters for an unsaturated polyester resin using 1% benzoyl peroxide at 15°C and 10°C. The promoters showed the following order of efficiency (by weight) as indicated by decreased gel and cure times: DMPT > DMPT/DMMT blends > DMMT > DMA. Under these conditions the optimum promoter concentration was 0.3%. At this level or higher, 80/20 and 60/40 DMPT/DMMT blends (wt/wt) performed essentially equal to DMPT but superior to DMMT and DMA. Examination of cured samples using differential scanning calorimetry showed that resins cured with DMPT or isomeric blends of DMPT and DMMT with high DMPT contents displayed higher glass transition temperatures and greater degrees of cure than samples cured using DMMT or DMA.
Optimization of a composite based on polyethylene blends and sepiolite. Effect of surface treatment of the filler and morphology of the composite on mechanical properties
Authors: Arroyo M. , Perez F. , Vigo J. P.
Published: April 2003

The optimization of a composite based on polyethylene blend matrices with unmodified and titanate coupling agent‐modified sepiolite has been studied. The analysis of the tensile, flexural, and impact behavior shows that the tensile and flexural properties, mainly the moduli, improve with increasing content of both filler and high‐density polyethylene (HDPE) in the composite. The surface‐modified sepiolite has a behavior similar to the unmodified one and no improvement of the mechanical properties is noticeable. In order to explain these effects a morphological study on fracture surfaces of the composites was performed using scanning election microscopy.
Property–composition dependence of isotactic poly(butene‐1)‐chlorinated polyethylene blends
Authors: Kallitsis J. K. , Kalfoglou N. K.
Published: April 2003

Melt‐mixed blends of isotactic poly(butene‐1) (PB) with chlorinated polyethylene (containing 48 wt % Cl) (CPE) were studied in the complete composition range. Phase contrast, polarizing, and scanning electron microscopy revealed that the blend is heterogeneous. The results were confirmed by the dynamic mechanical technique and differential scanning calorimetry. The latter technique indicated also that CPE does not influence the crystallinity of PB. Tensile behavior of the blends was good, especially at low CPE contents. The results were analyzed using phenomenological mechanics models. From the correlation obtained one can conclude that the blends are mechanically compatible. Limiting oxygen index data were also determined, to characterize the flammability behavior of the blends in the complete composition range.
Dielectric and optical properties of nitrogen‐incorporated polyethylene films fabricated by plasma polymerization
Authors: Kim S. H. , Xie H. K. , Kao K. C.
Published: April 2003

The dielectric and optical properties of nitrogen‐incorporated polyethylene films fabricated by radio‐frequency glow discharge in ethylene‐nitrogen (C2H4 − N2) gas mixtures have been measured for various nitrogen concentrations. The results show that the plasma‐polymerized films have distinct properties from the ones based on conventional chemical polymerization. The incorporation of nitrogen in polyethylene results in an increase in breakdown strength, dissipation factor, and dielectric constant at frequencies below the optical frequency range, and in a decrease in dark conductivity, and in photoconductivity and extinction coefficient in the optical frequency range. However, the incorporation of nitrogen does not cause significant change in refractive index. The effects of the incorporation of nitrogen in polyethylene are attributed to the shallow acceptor‐like traps introduced by incorporated nitrogen.
On the mathematical modeling of mechanochemical degradation of acrylonitrile–α‐methyl styrene–vinyl acetate terpolymer in conditions simulating the wet‐spinning
Authors: Oprea Cleopatra Vasiliu , Popa Marcel , Petrovan Simion
Published: April 2003

This article aims to carry out mathematical modeling of the mechanochemical degradation process of acrylonitrile–α‐methyl styrene–vinyl acetate ternary copolymer in conditions that simulate its wet‐spinning from dimethyl formamide solution. The influence of some factors on the mechanochemical degradation process is studied. Based on a great number of experiments a regression equation is determined, which correlates the intrinsic viscosity of the copolymer solution with the mechanical process variables (the length and length/diameter ratio, solution concentration, and pressure).
Rheological behavior of partially hydrolyzed poly(vinyl acetate‐co‐ethylene)
Authors: Han Chang Dae , Ma Yu‐Jiang , Chu Sung Gun
Published: April 2003

The rheological behavior of partially hydrolyzed poly(vinyl acetate‐co‐ethylene) (VAE) was investigated, using a Rheometrics Dynamic Mechanical Spectrometer. For the investigation, measurements of storage modulus (G′), loss modulus (G″) and loss tangent (tan δ) of the materials were recorded as functions of temperature at a fixed frequency (i.e., using temperature scans) and, also, as functions of frequency at a fixed temperature (i.e., using frequency scans). For the hydrolysis, three different grades of copolymer (containing 34, 47, 62 mol% of vinyl acetate) were used to yield poly(vinyl acetate‐co‐ethylene‐co‐vinyl alcohol) (VAEOH) with varying amounts of hydroxyl group. For comparison purposes, the viscoelastic properties of blends of VAE copolymer with poly(vinyl alcohol) (PVOH), having varying blend compositions, were also measured. The blends were prepared by first mixing a solution of VAE copolymer, which was dissolved in a toluene/dichloroethane mixed solvent, and an aqueous solution of PVOH, and then freeze drying the mixture to a constant weight. Also measured were the glass transition temperature (Tg) of the VAE copolymers and the Tg and melting point (Tm) of the VAEOH terpolymers, using a DuPont Thermal Analyzer equipped with a 910 DSC Module. It has been found that (1) introduction of hydroxyl group into the backbone of the amorphous VAE copolymer has made the resulting VAEOH terpolymer semicrystalline; (2) the Tm, Tg, G′, and the complex viscosity (η*) of the VAEOH terpolymers increase with increasing amounts of hydroxyl group; (3) the physical blending of PVOH with VAE copolymer has not affected the Tg of the VAE copolymer; (4) the G′ and η* of the VAE/PVOH blends are found to increase with the amount of PVOH in the blend. The use of logarithmic plots of G′ versus G″ has been found to be very useful for discerning the differences in the structure of the materials tested.
Graft copolymers from peroxidized EPDM rubber
Authors: Dean Barry D.
Published: April 2003

The transition metal catalyzed peroxidation of the pendant allylic functionality in EPDM rubbers with tertiary butyl hydroperoxide results in elastomeric, high polymer peroxides. The peroxidized EPDM rubbers are useful as free radical initiators for the polymerization and grafting of vinyl monomers in the preparation of comb‐type structures. The grafted EPDM rubbers are efficient impact modifiers for thermoplastic resins so long as the polymer grafted onto the EPDM is identical to or is thermodynamically miscible with the composition of said thermoplastic resin.
Study of polymer–solvent interactions by gas chromatography. Copolymers of vinyl acetate and vinyl alcohol with hydrocarbons and alcohols
Authors: Castells Reynaldo César , Mazza Germán Delfor
Published: April 2003

The specific retention volumes of nine hydrocarbons and 12 alcohols were measured at several temperatures within the range 120–150°C in columns whose stationary phases were poly(vinyl acetate) (PVAc) and four copolymers of vinyl acetate and vinyl alcohol with 94.8, 74.4, 60.9, and 43.4 mol % of vinyl acetate units (mol % VAc). No chromatographic retention for hydrocarbons was detected in columns loaded with poly(vinyl alcohol) (PVA) or a copolymer with 11.9 mol % VAc. The retention trends are discussed and the polymers solubility parameters (δ2) were computed from the measured Flory–Huggins χ parameters. The copolymers δ2 values increase almost linearly with decreasing mol % VAc; PVAc, however, has a distinct behavior. The limitations of the approach in the prediction of χ parameters are discussed.
Microcavity formation in poly(ester–carbonate) exposed to hot, humid environments
Authors: Robeson L. M. , Dickinson B. L. , Crisafulli S. T.
Published: April 2003

The behavior of polycarbonate in hot, humid environments has been well documented in the technical literature. Poly(ester–carbonate)s based on bisphenol A connected with carbonate and tere/isophthalate units are the subject of this investigation. Poly(ester–carbonate) exhibits many similarities to polycarbonate in microcavity formation when exposed to cycling hot, humid environments. These microcavities consist of concentric bands around a central nucleation site. Scanning electron microscopy reveals that the bands consist of rings of dense material alternating with rings of material containing microvoids. Water phase separation at the nucleation site (due to cycling temperature) leads to internal pressure and thus a dilatant stress around the edge of the microcavity. It is hypothesized that this allows for the ease of further water phase separation at the periphery of the microcavity, thus yielding microvoids. The mechanical properties of poly(ester–carbonate) exposed to 96°C water immersion and 132°C steam sterilization cycling were determined and show significant loss in performance in these environments similar to that previously reported for polycarbonate.
Ionic photoinitiators for radical polymerization in direct micelles: The role of the excited states
Authors: Fouassier J. P. , Lougnot D. J.
Published: April 2003

Radical photopolymerization reactions of MMA in direct anionic and cationic micelles are investigated in the presence of different types of ionic initiators, through steady state illumination experiments and time‐resolved laser spectroscopy. The positively charged ionic photoinitiator BP+ appears as the more efficient. The reactivity of the excited states involved as well as the behavior of the side radicals produced seem to govern for a large part the practical efficiency of these compounds. A general discussion on the role of the different factors (localization, electronic effects, monomer quenching, electron and proton transfer processes, radical exit from the micelle, and acid–base equilibrium) is presented.
Poly(phenylene oxide) composites containing crosslinked polystyrene microspheres. I. Stress–strain properties
Authors: Zhikuan Chai , Tiangui Wang , Qipeng Guo
Published: April 2003

The stress–strain properties of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polystyrene composites containing crosslinked polystyrene microspheres have been measured at strain rates of 0.167, 1.67, and 16.7 min−1. It is found that Young's modulus almost has no increase with the filler content. The elongation at break and tensile strength decrease with the volume fraction of the filler, but both tend to flatten out at the volume fraction νf > 0.25 at the strain rate of 1.67 min−1. The two ultimate tensile properties also have maximum values in the relationship with strain rate at the same filler concentration and strain rate conditions. Considering that elongation can be brought about by both matrix and filler, the well‐known equation of elongation at break becomes
Low‐angle laser light scattering–aqueous size exclusion chromatography of polysaccharides: Molecular weight distribution and polymer branching determination
Authors: Yu Li‐Ping , Rollings J. E.
Published: April 2003

A low‐angle laser light scattering detector (LALLS) used with size exclusion chromatography (SEC/LALLS) has been applied for the determination of molecular weight, molecular weight distribution (MWD), and degree of branching of polysaccharides in 0.5N NaOH aqueous solution. Data from both detectors [differential refractive index (DRI) and LALLS] are used to calculate the absolute molecular weight at each point in a sample chromatogram. The correct average molecular weight and MWD can be obtained without calibration methods used in conventional SEC. As a consequence of this technique, Mark—Houwink coefficients can be predicted from a single broad‐distribution, homopolymer without recourse to time‐consuming fractionation methods. Moreover, the hydrodynamic volume separation mechanism of SEC can be exploited with the SEC/LALLS method to gain information about polymer branching. In the studies described in this paper, SEC/LALLS has been employed to obtain data about the branching parameters gv and gM for samples of amylose, amylopectin, starch, and glycogen. For three homopolymers (amylose, amylopectin, and glycogen), branching frequency (as measured by chemical means), and the branching parameters (gv and gM) are inversely related. This trend is consistent with theoretical predictions. For starch, a nonhomogeneous branching distribution is observed as a function of molecular weight.
Derivative ultraviolet and visible spectrophotometry: Applications to polymer analysis
Authors: Mori Sadao
Published: April 2003

First‐ to fourth‐derivative spectra of humic acids, polystyrene, and mixtures of several prepolymers were measured and the advantage of derivative spectrophotometry such as resolution enhancement and background correction was discussed. Although the vis‐absorption spectra for humic acids in pH solutions from pH 2.0 to 10.0 could be hardly discriminated, humic acids in solutions above pH 7.0 could be clearly distinguished from those in solutions below pH 6.0 by first‐derivative spectrophotometry. Similarly, the first‐derivative spectra of the copper‐humic acid complex were different from those of free humic acids, though both absorption spectra resembled each other. UV absorption spectrum of a mixture of phenol‐novolac resin and methylated methylol‐melamine resin was similar to and the second‐derivative spectrum was different from that of phenol‐novolac resin. The difference of derivative spectra of a mixture of polycarbonate and epoxy resin was also discussed. Shoulder and unresolved peaks were clearly revealed by differentiation of absorption spectra and peak assignments from the fourth‐derivative spectra were more accurate than those from the absorption spectra. This advantage was discussed by using polystyrene as an example.
Effect of thermal hysteresis on melting of syndiotacticity‐rich poly(vinyl alcohol) hydrogel
Authors: Yamaura Kazuo , Takahasi Tatsuya , Tanigami Tetsuya , Matsuzawa Shuji
Published: April 2003

The melting temperatures (TM) of hydrogels prepared by chilling aqueous solutions of syndiotacticity‐rich poly(vinyl alcohol) (s‐PVA) at 0°C were measured rising temperature of gels from the initiative temperature (TI) of 0–70°C (every 10°C). The apparent enthalpies of fusion of a junction ΔH's were estimated from the relation between the logarithm of polymer concentration (log C) and 1/TM. ΔH depended on TI, showing that the melting point of gels depended on a thermal hysteresis. The highest polymer concentration CH in those of the gels which have no melting point above an initiative temperature was determined and ΔH was estimated from the relation between log CH and the reciprocal melting point of the gels with CH, 1/TIM. The ΔH was 15.1 kJ/mol in the range of higher polymer concentrations and 43.9 kJ/mol in the range of lower concentrations.
Analysis of the flow behavior of HDPE/LDPE blends using a kinetic network model
Authors: Manero O. , Rangel‐Nafaile C. , García‐Rejón A.
Published: April 2003

Theoretical predictions of the flow behavior of high and low‐density polyethylene polymer blends have been obtained using the kinetic network model proposed by Williams et al. The results show that this model can be used even in the case of polydisperse components having similar relaxation spectra. Furthermore, in order to obtain meaningful predictions, the characterization of the complete system (blends and pure components) should be carried out on samples with the same thermomechanical history. Experimental data show that the shearing history influences the rheological properties of the pure homopolymers to a measurable and significant degree and that it has to be taken into account when these properties are used to predict the flow behavior of their blends.
Study on ketalization reaction of polyvinylalcohol by ketones. I. Reaction between polyvinylalcohol and acetone
Authors: Nakamura Naofumi
Published: April 2003

Ketalization reaction of polyvinylalcohol (PVA) by acetone, dimethylsulfoxide (DMSO) as solvent, under the presence of acidic catalyst, in homogeneous system was carried out and the synthesis of polyvinylketal with any ketalization degree was successfully performed. This reaction proceeds in bimolecular reaction, the equilibrium constant is ca. 0.07 at 40°C and roughly 10−5 less compared with the acetalization reaction between PVA and aldehydes. Synthesis in aqueous media is difficult. However, the heat of reaction for both cases is 7.5 kcal/mol and both reactions are considered to proceed in an identical reaction mechanism. Ketalization reaction starts from isotactic OH portion and proceeds finally to syndiotactic OH portion, however, 100% ketalization is extremely difficult. The effects of water on reaction was confirmed both from theoretical and experimental viewpoints, and even though the presence of water lowers the degree of ketalization, it was observed that the presence of water below 0.1 mol against 1 mol of PVA will not significantly affect final ketalization degree. Polyvinylketals thus obtained are soluble in DMSO, dimethylformamide (DMF), and alcohols.
Characterization of the cure of TGDDM/DDS epoxy resins by chemiluminescence I. Spectral and thermal analysis
Authors: George G. A. , Schweinsberg D. P.
Published: April 2003

The emission of weak visible chemiluminescence (CL) during the cure of a tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM)‐based epoxy resin, with three different concentrations of 4,4′‐diaminodiphenylsulfone (DDS) has been studied at 135°C. Spectral analysis indicates that the CL originates from trace oxidation of the TGDDM resin and the emission intensity is sensitive to the viscosity changes during cure. From thermal analysis data, sharp discontinuities in CL intensity are shown to occur at the gel point. The temperature dependence of CL from a cured resin also shows a sharp discontinuity at Tg. These results indicate that CL provides a sensitive monitor of both the kinetics of gelation and the network formation in this epoxy resin.
Dielectric properties of an epoxy resin and its composite II. Solvent effects on dipole relaxation
Authors: Reid Jonathan D. , Buck Richard P.
Published: April 2003

Dipole relaxation dielectric loss behavior of a fiberglass‐epoxy composite has been studied following submersion in polar and nonpolar organic solvents as well as in acidic and basic aqueous solutions. Certain adsorbed organic solvents, such as 1,2‐dichloroethane, had little influence on the epoxy relaxation behavior. Other solvents, including chloroform, increased the composite relaxation intensity and shifted the temperature‐frequency region over which the relaxation occurred. Both the amount of solvent uptake and the degree of interaction of solvent molecules with epoxy polar functional groups appear to control the amount of relaxation behavior perturbation. Arrhenius activation energies for relaxation were lowered by solvent uptake from the dry composite value of 18 kcal/M to between 6 and 16 kcal/M, depending on the solvent adsorbed. Submersion in methanol and chloroform sharply increased the direct current conductivity of the composite. Two molar acidic and basic solutions had little influence on composite dipole relaxation behavior other than the well known behavior associated with moisture uptake.
Selective separation of water from water–ethanol solution through quarternized poly(4‐vinylpyridine‐co‐acrylonitrile) membranes by pervaporation technique
Authors: Yoshikawa Masakazu , Yukoshi Takashi , Sanui Kohei , Ogata Naoya
Published: April 2003

Polymer membranes having cationic charge site, poly(1‐alkyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (alkyl: methyl, butyl, or octyl) were prepared in terms of coulombic interaction for separation of water–ethanol mixtures. The incorporation of cationic charge site into the membrane led to improve not only separation factors (selectivity toward water) but also flux number in the separation of aqueous ethanol solution by pervaporation technique. Target values, which were requested to have from the viewpoint of industrial utilization for separation of aqueous ethanol solution were attained as follows: separation factor toward water over 50 and flux value over 500 g m−2 h−1, through poly(1‐methyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (membrane 3) (quarternized fraction of pyridinium moiety, 89.5%; mol fraction of pyridinium moiety, 0.034) and poly(1‐butyl‐4‐vinylpyridinium iodide‐co‐acrylonitrile) (membrane 5) (quarternized fraction, 100%; mol fraction of pyridinium moiety, 0.038). It was found that the introduction of cationic charge site into the membrane was one of feasible methods to obtain suitable membranes for water permselective membranes in the separation of water–ethanol mixtures.
Rates of property change in plasticized filled PVC compounds
Authors: Ajji A. , Schreiber H. P. , Rudin Alfred
Published: April 2003

Rheological and mechanical properties of polyvinyl chloride (PVC) compounds vary with the polymer entanglement state at the time of testing. Controlled shearing episodes and thermal histories applied to the compounds produce major property variations. These then relax toward steady‐state values at rates which are consistent with diffusion‐controlled processes, presumably connected with the development of steady‐states in entanglement couplings. Activation energies of 4–7 kcal/mol apply to the proposed re‐entanglement processes. Rates of property variation can be altered by the addition of fillers to the compounds, the interactions between polymer and filler being an important factor in this regard. CaCO3 samples with strong affinity for the PVC retard the rate of property variations (i.e., the filler tends to stabilize non‐steady‐state entanglement couplings). Fillers, surface treated so as not to interact strongly with the polymer, produce lesser effects on relaxation rates. The data indicate the feasibility of controlling both the sensitivity of polymer properties to processing variables, and the rates of property change associated with the attainment of steady‐state polymer entanglement morphologies.
The application of bulk polymerized acrylic and methacrylic interpenetrating polymer networks to noise and vibration damping
Authors: Foster J. N. , Sperling L. H. , Thomas D. A.
Published: April 2003

Novel acrylic/methacrylic interpenetrating polymer networks (IPNs) were examined by dynamic mechanical spectroscopy for their damping capabilities. While simple homopolymers exhibit high damping properties only over a 20–30°C range, multicomponent polymer systems with controlled degree of miscibility, such as IPNs, may exhibit high damping properties over temperature ranges as broad as approximately 100°C. Two series of IPNs based on poly(n‐butyl acrylate) and poly(n‐butyl methacrylate) were synthesized and the dynamic mechanical properties were investigated using a Rheovibron. Graphite was incorporated into the poly(n‐butyl acrylate) homopolymer and a few IPNs to measure the change in the damping properties. For important IPN compositions, tan δ values between 0.4 and 0.85 were observed over a 75°C plus temperature range. Graphite increased the damping properties of poly(n‐butyl acrylate) and the IPNs, as indicated by the tan δ values.
Concentration dependence of solvent self‐diffusion coefficients
Authors: Vrentas J. S. , Chu C.‐H.
Published: April 2003

The concentration dependence of solvent self‐diffusion coefficients is examined near the pure solvent limit. It is shown that it is possible to explain an apparently anomalous concentration dependence for the solvent self‐diffusion coefficient at high penetrant mass fractions within the framework of the free‐volume theory of transport.
The effect of thermal history on the distribution of residual stresses in PMMA rods
Authors: Mittal Ramesh K. , Rashmi Vibhu
Published: April 2003

A nondestructive technique based on the photoelastic properties of transparent polymers has been used to monitor the distribution of residual stress components in circular rods of poly(methyl methacrylate) (PMMA). The influence of various thermal histories on these stresses as well as on the molecular birefringence has been determined. The technique has been further simplified to obtain the values of maximum tensile and compressive residual stresses with the help of just two photoelastic measurements. The stresses so obtained are within 10% of the values obtained using detailed experimental measurements and their analysis. The simplified procedure is, therefore, suitable for “on‐line” determination of residual stresses in extrusion industry.
The effect of sorbed penetrants on the aging of previously dilated glassy polymer powders. I. Lower alcohol and water sorption in poly(methyl methacrylate)
Authors: Connelly R. W. , McCoy N. R. , Koros W. J. , Hopfenberg H. B. , Stewart M. E.
Published: April 2003

Sorption kinetics and equilibria for methanol, ethanol, and n‐propanol in 0.544 μm diameter poly(methyl methacrylate) microspheres were determined at 35°C over a wide range of relative pressures. Sorption isotherms were concave to the pressure axis at low relative pressures and convex to the pressure axis at higher relative pressures. These results, considered in the context of recently reported data for high pressure sorption of gases in polymeric glasses, suggest that the S‐shaped isotherms reported here are examples of a generalized isotherm which describes sorption behavior of all penetrants in glassy polymers if an appropriate range of concentration is traversed by the experimental protocol. The effects of dialating the microspheres by preswelling with methanol were studied by subsequent low pressure sorption of water, methanol, ethanol, and n‐propanol at 35°C. The preswollen microspheres exhibited initially higher sorption capacities than the as‐Received samples, but tended to consolidate with time following the preswelling treatment. The aging process, monitored by periodic short‐term sorption with the various penetrant probes, was arrested by contacting the microspheres with an activity of n‐propanol sufficient to maintain a sorbed concentration of approximately 1 wt %. The aging was significantly retarded by the presence of low concentrations of water and ethanol. Conversely, the aging process appeared to be essentially unaffected by the presence of correspondingly low concentrations of methanol. The complex kinetics describing the sorption of the various penetrants ranged from Fickian diffusion to polymer relaxation‐controlled absorption, depending upon penetrant, relative pressure, and prior exposure history. The low temperature preswelling of the microspheres markedly increased the rate of sorption as well as the respective apparent equilibrium sorption.
Residual stress and thermal expansion of spun‐on polyimide films
Authors: Elsner Gerhard
Published: April 2003

The residual stress in spin coated films and the effect of heat treatments on this stress were determined by the Fizeau interference method. Three types of spin coated polyimide (PI) films have been studied. Two of them were prepared by thermal conversion of their poly(amic acid)s (PAAs) and the third one by solvent evaporation of the soluble preimidized PI. For the imidized PI films the residual stress vs. bake temperature shows an inclined steplike behavior while this function for soluble PI is approximately linear. The room temperature stress relative to silicon substrates in fully baked films (400°C) is between 40 and 70 MPa and nearly independent of the film thickness. From the stress measurement, the thermal expansion coefficient and Young's moduli have also been obtained. The thermal expansion coefficient and the Young's modulus are in the order of 9.0 × 10−6°C−1 and 10 GPa, respectively. These values deviate from those published for bulk material which is explained by the in‐plane orientation of the molecular chains in spun‐on PI films.
Investigations of the action of flame retardants in cellulose. II: Investigation of the flame‐retardant action of polyphosphonitride in cellulose
Authors: Choudhary Manjeet S. , Fink Johannes K. , Lederer Klaus , Krässig Hans A.
Published: April 2003

Pure regenerated cellulose fibers and those containing various amounts of phosphorus nitride were pyrolyzed under different conditions in the temperature range of 150–440°C. Easily volatile liquid pyrolysis products, the tar fraction of limited volatility, and the charred residue were determined gravimetrically. The liquid volatiles were analyzed by combined gas chromatography/mass spectrometry for their water content. The tarnfraction and the charred residue were inspected by infrared (IR) spectroscopy. The studies revealed that the phosphorus nitride flame retardant enhances the onset of the pyrolytic decomposition and the release of water at substantially lower temperatures as observed for pure cellulose. The water release favors the carbonization and its extent reduces the formation of levoglucosan as a precursor of easily flammable pyrolysis products. Thus phosphorous nitride must be classified into the water release favoring flame retardants.
Latex interpenetrating polymer networks based on acrylic polymers. IV. The influence on mechanical properties of the time of swelling the seed particles with the second monomer
Authors: Hourston D. J. , Satgurunathan R. , Varma H. C.
Published: April 2003

Two latex interpenetrating polymer networks, one based on a partially compatible pair and the other based on an incompatible pair of polymers, were prepared by a two‐stage emulsion polymerization. To investigate the effect of swelling the first formed polymer particles with the second monomer, the second stage of the synthesis was conducted after allowing the second monomer to be in contact with the seed latex for specified periods of time. Fabricated samples of these interpenetrating polymer networks were subjected to hardness, stress–strain, and dynamic mechanical measurements. The results showed an enhancement in mixing of the two networks in the case of the partially compatible pair and a detectable increase in the level of mixing for the incompatible pair.
Evaluation of adhesion characteristics of nylon‐6 tire cord to natural rubber
Authors: Mukherjee A. K. , Kulkarni S. G. , Chakravarty S. N.
Published: April 2003

The adhesion characteristics of Nylon‐6 cords to rubber matrix, using Resorcinol Formaldehyde Latex (RFL) solution, were evaluated at various conditions. The heat‐setting studies of RFL dipped cords in the temperature range of 180–210°C showed a loss in tensile properties. However, a minimum in the loss was observed when a pretension load was given to the cords. Percent shrinkage of RFL‐dipped cords increased with the increase in temperature of heat setting. Adhesion behavior of Nylon‐6 cords to rubber matrix showed some improvement under relaxed conditions in the entire temperature range studied. With the application of suitable tension to cord, adhesion behavior can be made constant. This has been attributed to the higher extent of shrinkage of cords under relaxed conditions providing greater cord surface area. This in turn, leads to increased cord to rubber matrix.
Preparation and properties of very thin films of syndiotacticity‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Ikeda Ken‐Ichi , Fujii Masaharu , Yamada Ryoji , Tanigami Tetsuya , Matsuzawa Shuji
Published: April 2003

Very thin films of poly(vinyl alcohol) could be prepared by utilizing the adsorption of polymer molecules at air/water interface from the aqueous solutions of the poly(vinyl alcohol) derived from vinyl trifluoroacetate. The films prepared by the bubble method were thinner than those obtained by the frame method. The minimum thickness of the former films was 260 Å and that of the latter was 1800 Å. These very thin films resisted water at temperatures below 55°C. The maximum Young's modulus of the drawn/annealed films prepared from these samples was 30 GPa. The permeability of water, Jw/δP, was 2–6 × 10−3 cm · s−1 atm−1 (0–55°C) for the untreated film (thickness: 1800 Å) prepared by the frame method and 0.8–2.2 × 10−2cm · s−1 · atm−1 (5–55°C) for the untreated film (360 Å) prepared by the bubble method, and depended on the thickness of film.
Synthesis, crosslinking and degradation of some unsaturated polyester resins
Authors: Doss Ninette L. , Habib Samia , Nosseir Michael H.
Published: April 2003

Some unsaturated polyester resins were prepared by the ester interchange between p‐carbethoxymaleananilic acid and p‐carbethoxysuccinanilic acid with saturated and unsaturated diols. Moreover, copolymers were also synthesized by the polyesterification of the aforementioned acids and maleic anhydride with the above‐mentioned glycols. The structure of both the unsaturated polyester resins and copolymer resins was established by IR, UV, and NMR spectroscopy. Also, viscosity measurements and molecular weight determinations were further tools for their structural elucidation. All the products were attempted to cure with styrene in the presence of benzoyl peroxide as initiator, and the produced network structures, in the form of films, were tested as surface coating materials for glass and metals. The structure of the cured products was established after their degradation, by physical and spectroscopical means.
Dynamic viscoelastic properties in the molten state for cellulose acylates and (cellulose oligo‐oxymethylene ether) acylates
Authors: Shiratsuchi Kentaro , Matsumoto Takayoshi , Yao Shigeru , Shiraishi Nobuo
Published: April 2003

The dynamic viscoelastic properties of cellulose acylates, its mixed acylates, and (cellulose oligo‐oxymethylene ether) acylates (COM acylates) have been meausured in the molten state over wide ranges of frequency and temperature. The log G′ vs. log ω curves as well as the similar curves for the loss modulus G′ at various temperatures for cellulose acylates could not be superposed into respective master curves by use of the time–temperature superposition principle. This is considered to be caused from the orientation of cellulose acylates main chain in the molten state. In the case of cellulose mixed acylates, rheological simplicity was found but this was only the case on selected combinations of acyl groups. Most cellulose acylates, which were introduced oxymethylene chains (OM chains) in between glucopyranose ring and the acyl group, behaved as thermorheologically simple materials in the molten state. When the acyl groups become large, however, it is necessary to introduce long OM chains in order to get thermorheologically simple COM acylates in their molten state. Several studies have been made concerning the behavior of side chains, both the OM and the acyl chains, of COM acylates in the molten state.
Effect of water on vapor phase photografting on cellulose and its derivatives
Authors: Kubota Hitoshi , Ogiwara Yoshitaka , Hinohara Sakae
Published: April 2003

Effect of water on vapor phase photografting on cellulose was investigated at 60°C. An activated grafting of methyl methacrylate by water contained in the sample was observed in the experiment. The effect of water was commonly recorded irrespective of the type of cellulose derivatives such as cellulose acetate (degree of substitution, DS = 0.18 and 0.33), cellulose nitrate (DS = 0.35 and 0.75), and carboxymethl cellulose (DS = 0.19 and 0.74). Organic solvents can also be used in place of water, indicating that the percent grafting decreases in the order, water > methanol > acetone > cyclohexane. From ESR studies, water in the sample was found to contribute to the decay of cellulose radicals rather than to the radical formation. The decay was accelerated by organic solvents, and the magnitude of the effect was in the order, water ≈ methanol > acetone > cyclohexane. Based on the above investigation, it was presumed that water contained in the sample cannot contribute directly to the formation of cellulose radicals which may initiate grafting, but mostly promotes the penetration of monomer into cellulose fibers. Such penetration could lead cellulose radicals to an effective initiation of grafting.