bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of syndiotactic‐rich poly(vinyl alcohol) thin film in water. III. Contraction and extension of drawn and annealed thin film in water
Authors: Yamaura Kazuo , Matsuzawa Shuji 
Published: April 2003

AbstractContraction and extension behaviors in water for drawn (four times original length) and annealed (at 60–215°C) thin films of poly(vinyl alcohol) (PVAVTFA) derived from vinyl trifluoroacetate have been examined. At a constant temperature of 25°C, drawn films annealed at 60–190°C contracted after a certain standing time. Length of films annealed at 200°C did not change after standing of 20 min and film annealed at 215°C extended very little. As the temperature was raised, the drawn films annealed at 60–190°C contracted further until a certain temperature and then extended. The drawn film annealed at 200°C first started contraction at 70°C. The drawn film annealed at 215°C extended further very little until 75°C and then contracted very little until 99°C (in boiling water). In standing at 99°C, it contracted very little with standing and resisted without breaking for 300 min.
A study on blends of different molecular weights of polypropylene
Authors: Deopura B. L. , Kadam S. 
Published: April 2003

AbstractBlends of small percentage of plastic grade polypropylene with fiber grade polypropylene are studied in unoriented and oriented states. A 3% blend sample has a higher spherulitic growth rate, and improved mechanical behavior in drawn fiber state as compared to the parent sample. These changes are related to the presence of bimodal and trimodal crystal texture of polypropylene in the blend, respectively. At a higher blend percent, specifically at 10 and 15%, the mechanical properties of the drawn fiber are inferior and these are related to partial phase segregation of the components.
Preparation of block copolymers with polymeric azocarbamate as an initiator
Authors: Yürük H. , Özdemir A. B. , Baysal B. M. 
Published: April 2003

AbstractBlock copolymers containing polystyrene and poly(ethylene oxide) or poly(propylene oxide) segments were prepared via chemical reactions. A stepwise procedure was first employed to prepare macroazocarbamates by capping poly(ethylene oxide) glycols or poly(propylene oxide) glycols and an aliphatic diisocyanate and subsequently by reacting this intermediate with an azobisalcohol. This macroazocarbamate was later used to initiate free radical polymerization at elevated temperatures. Styrene contents, molecular weights, and elastic modulus‐temperature relationships were determined.
Crystallinity and dicumyl peroxide diffusivity in low density polyethylene with different thermal histories
Authors: Gupta J. P. , Sefton Michael V. 
Published: April 2003

AbstractThe absorption diffusivity of dicumyl peroxide (DICUP) in low density polyethlene pellets that have been annealed and either cooled slowly or quenched has been measured and correlated with the corresponding changes in crystallinity as measured by DSC. Annealing at 125°C resulted in an increased crystallinity and decreased DICUP diffusivity (3.2 × 10−7 cm2/s for as supplied pellet to 5.2 × 10−8 cm2/s for annealed and slowly cooled pellets). Quenching the annealed pellet reduced the increase in crystallinity and corresponding decrease in diffusivity. The time course of annealing and secondary crystallization processes was defined through further DSC measurements. The relationship between crystallinity and pressure for both hot press films and 4 mm diameter extrudate was found to be identical, Indicating the importance of pressure on bulk crystallization phenomena regardless of the source of the pressure.
Formation of polyelectrolyte complexes between cellulose derivatives and their blood compatibility
Authors: Ito Hiraku , Shibata Toru , Miyamoto Takeaki , Noishiki Yasuharu , Inagaki Hiroshi 
Published: April 2003

AbstractFormation of polyelectrolyte complexes (PECs) between cellulose derivatives in aqueous solution and their blood compatibility were examined. To this end, two types of quaternary ammonium cellulose derivatives, Q‐Cell and Q‐HEC, were prepared by treating cellulose and hydroxyethyl cellulose (HEC), respectively, with glycidyl trimethylammonium chloride. Anionic derivatives were carboxymethyl cellulose (CMC) with different degrees of substitution (DS) and cellulose sulfate (CS). In vivo blood tests were made by a method of peripheral vein indwelling suture. The results showed that the complex formation of Q‐Cell did not follow a stoichiometric reaction, but Q‐HEC reacted stoichiometrically with CMC and CS. It was also found that water‐insoluble cellulosic PECs are soluble in formic acid, showing that the cellulosic PEC films can be prepared from formic acid solutions. The blood tests revealed that by the criteria of the test method employed in this work, cellulosic PECs had a good blood compatibility.
Thermal analysis of the glass transition of plasticized poly(vinyl chloride)
Authors: Beirnes Kimberley J. , Burns Charles M. 
Published: April 2003

AbstractEarlier studies by differential scanning calorimetry showed anomalous behavior of Tg with varying amounts of dioctyl phthalate, while by dynamic mechanical analysis 2 Tg's were found over a limited concentration range. In this study, two adjacent Tg's were found over the complete range of concentrations of dioctyl phthalate or dioctyl adipate, changing in relative contributions over the range. The results are shown to be consistent with the earlier work and to fit the Couchman model more closely than other models tested.
A study of polyion‐enzyme complexes: Quaternized poly(vinyl dimethylaminobenzal)‐glucose oxidase‐potassium poly(acrolein bissulfate) complex
Authors: Hua Jiadong , Liu Lu , Yin Rui , Fang Shibi , Jiang Yingyan 
Published: April 2003

AbstractThis report has mentioned a study that includes preparation of a polyion‐enzyme complex consisting of quaternized polyvinyl dimethylaminobenzal (QPVDAB), potassium polyacrolein bissulfate (KPABS), and glucose oxidase (COD), and evaluation of relationships between properties and structure of the complex are discussed.
Accelerated weathering of butadiene–styrene‐based rubber
Authors: Abu‐Zeid M. E. 
Published: April 2003

AbstractPhotoacoustic spectroscopy (PAS) was used for the study of accelerated weathering of some selective samples of butadiene–styrene rubber. It was found that, although their accelerated degradation is mainly due to the combined effects of UV and heat, the rate of their degradation solely depends on their compositions.
Prediction of stress–relaxation data of some nylons from stress–strain data
Authors: Bradley W. V. , Williams H. Leverne 
Published: April 2003

AbstractSix commercially available nylons were tested for stress–strain and stress–relaxation properties. Use was made of a recently revealed approach to predicting viscoelastic properties beyond the linear region from an analysis of the stress–strain curve. The equations used were three‐dimensional employing the Halsey–Eyring viscoelastic model. The necessary constants were calculated and, when applied to the appropriate equations, reconstituted the stress–strain curve and predicted the stress–relaxation curves quite well.
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

Abstractp‐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

AbstractTensile 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

AbstractWater‐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

AbstractThermal 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

AbstractThe 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

AbstractAn 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

AbstractThe 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

AbstractThe 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

AbstractLinear 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

AbstractNew 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

AbstractThe 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

AbstractN,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

AbstractThe 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

AbstractMelt‐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

AbstractThe 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

AbstractThis 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).