bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal orientation in injection molding of talc‐filled polypropylene
Authors: Fujiyama Mitsuyoshi , Wakino Tetsuo 
Published: April 2003

AbstractThe crystal orientation in injection molding of talc‐filled polypropylene has been studied by means of polarizing microscopy and X‐ray diffraction measurements. The plate planes of talc particles are aligned parallel to the surface of injection molding. The c‐ and a*‐axes of polypropylene crystals are bimodally oriented to the flow direction, and the b‐axes are oriented to the thickness direction. Namely, the crystals in the injection molding of talc‐filled polypropylene show a kind of uniplanar‐axial orientation according to the classification of Heffelfinger and Burton. The degree of the bimodal orientation of c‐ and a*‐axes decreases toward the interior of the injection molding. The b‐axis orientation is strong throughout the thickness direction, although it is a little weaker at the surface skin and central regions. This peculiar crystal orientation originates from the flaky shape and crystallization nucleation ability of talc particles. In a mold cavity, talc particles are aligned parallel to the cavity wall by the action of flow, and crystallization progresses, with the (040) plane of polypropylene crystal piling on the plate planes of talc particles and the b‐axis, which is the growth direction of polypropylene crystal, being aligned to the thickness and cooling direction of injection molding. The crystal orientation in injection molding of unfilled polypropylene is basically similar to that of talc‐filled polypropylene, although the b‐axis orientation to the thickness direction is much weaker.
Vinyl‐terminated oligomeric ethers: A study of the crosslinking process
Authors: Barton S. J. , Ghotra J. S. , Matthews A. E. , Pritchard G. 
Published: April 2003

AbstractA thermosetting resin consisting of a mixture of vinyl‐terminated oligomeric ethers was prepared by a two‐step synthesis. This required the reaction of 1,4‐bis (chloromethyl) benzene with the potassium salt of bisphenol A, and subsequent vinylation of the chloromethyl end groups by means of a Wittig reaction. The linear vinyl prepolymers were thermally crosslinked through their reactive styryl end groups (without the addition of catalyst) to produce castings and woven glass laminates. A study of the crosslinking process was carried out by differential scanning calorimetry (DSC). The water absorption and the thermooxidative stability of the crosslinked polymer were investigated. A styrene solution of the oligomeric ethers was also crosslinked, using benzoyl peroxide as a catalyst. The moisture absorption characteristics of the crosslinked styrene copolymer were compared with those of the crosslinked homopolymer. Both substances showed hydrophobic character.
Studies on laser‐induced irreversible surface softening in a thermoset polymer of allyl diglycol carbonate (CR‐39)
Authors: Kukreja Lalit Mohan 
Published: April 2003

AbstractIt is shown that controlled irreversible surface softening can be obtained in thermoset polymer of allyl diglycol carbonate (CR‐39) without degrading its bulk properties on treating it with a cw‐CO2 laser. An average value of the threshold fluence for the onset of softening is found to be about 9 J/cm2, which changes slightly with the interaction time and power density of the laser beam. Beyond this threshold the hardness of the treated surface decreases on increasing the power density and/or the interaction time till the onset of volatile decomposition in this polymer, which takes place at the laser fluence of 25 J/cm2. Thereafter, the hardness tends to saturate at nearly 60% of its original value for the untreated surface. Formation of a new heterogenous interlinked porous microstructure has been observed in the laser softened polymer surface. Solution of the 1‐dimensional heat flow equation incorporating the temperature‐dependent decomposition energy of CR‐39 has shown that at 9 J/cm2 the surface attains the maximum temperature of about 280°C and then cools at a rate of about 103°C/s. The starting value of the surface cooling rate increases with the fluence. A part of the absorbed energy goes in for the depolymerization, which is found to increase from about 0.004 to 4.5 J/cm2 when the laser fluence is increased from 9 to 25 J/cm2. The laser‐induced depolymerization and subsequent rapid cooling of the surface explain the observed effects.
Plasticized PVC films/petroleum oils: The effect of ultraviolet irradiation on plasticizer migration
Authors: Duvis T. , Karles G. , Papaspyrides C. D. 
Published: April 2003

AbstractPlasticizer migration from flexible poly(vinyl chloride) comprises an important aspect, especially when packaging foodstuffs and pharmaceuticals. Much of the published work has been intended either to correlate migration into simulants with that into foods or to study migration into simpler extractants, enabling the various parameters involved in migration to be studied in isolation. According to the latter approach, the migration of dioctyl phthalate into petroleum oils has been studied already in our laboratory and in this paper results are presented in an attempt to reduce or prevent migration by u.v. irradiation. The effect of irradiation time on short and long‐term migration behavior was examined together with the influence of the immersion temperature. The nature of the liquid environment seemed to be a predominant aspect: high viscosity oils presented a satisfactory behavior in contrast with those of lower viscosity in which the prevention effect was rather negligible. On the other hand, primary kinetics studies yielded similar results with those already established for untreated material (i.e., good conformity to the short time Fickian approximation).
Poly(sodium acrylamidoalkanoate) s: Syntheses and solution properties in relation to flocculation study in water treatment
Authors: Gan L. M. , Yeoh K. W. , Chew C. H. , Koh L. L. , Tan T. L. 
Published: April 2003

AbstractThe micelle‐forming monomers of sodium 6‐acrylamidocaproate (Na 6‐AAC), sodium 11‐acrylamidoundecanoate (Na 11‐AAU), sodium 11‐(N‐methylacrylamido) undecanoate (Na 11‐MAAU), and sodium 11‐(N‐ethylacrylamido) undecanoate (Na 11‐EAAU) have been synthesized and polymerized. Except poly(Na 6‐AAC), the molecular weights of the other three poly(sodium acrylamidoalkanoate) s were over 106. They behave as strong anionic polyelectrolytes in aqueous solutions. Their solution properties, such as viscosity, charge density, and radius of gyration, were investigated. The performance of these anionic polyelectrolytes as coagulant aids in water treatment were assessed by jar test. Poly(Na 6‐AAC) and poly (Na 11‐AAU) were superior to poly (Na 11‐MAAU) and poly (Na 11‐EAAU) in terms of flocs settling. All these four anionic polyelectrolytes tested in water treatment are as effective as a commercially available cationic polyamine organic coagulant (Hyperfloc CP 753).
Segmented block copolymers based on liquid natural rubber
Authors: Ravindran T. , Nayar M. R. Gopinathan , Francis D. Joseph 
Published: April 2003

AbstractSegmented block copolymers were prepared from hydroxyl‐terminated liquid natural rubber (HTNR) and poly(ethylene oxide) (PEO). Toluene 2,4 diisocyanate (TDI) was used as the coupling agent for combining both types of segments. Keeping the molecular weight of HTNR constant, a series of materials were prepared using PEO with varying molecular weights. Their thermal and mechanical properties were evaluated. With increasing the PEO content, the properties vary from soft to rigid elastomers and rubber‐toughened plastics. This variation in properties is caused by the changes in the sample morphology, which depends on the relative fractions of the hard and soft segments. Water absorption capability of these block copolymers was determined. Hydrogels with water content approximately up to 80% were obtained.
Properties of polypyromellitimides containing phosphorus
Authors: Varma I. K. , Kumar Ramakant , Saxena Sneh , Varma D. S. 
Published: April 2003

AbstractThe paper deals with the synthesis and characterization of seven polypyromellitimide samples having varying contents of phosphine oxide and ether linkages in the backbone with pendant maleimido groups. Curing characteristics and thermal stability of polymers were evaluated by differential scanning calorimetry and dynamic thermogravimetry. It was observed that an increase in pendant maleimido groups resulted in an increase in the heat of polymerization. Char yield also increased with increase in phosphorus content. Conductivity and dielectric parameters were also evaluated. The mechanism of conduction was found to be a combination of electronic and ionic type.
Sulfonated polyisobutylene telechelic ionomers. XIV. Viscoelastic behavior of concentrated solutions in nonpolar solvents
Authors: Tant Martin R. , Wilkes Garth L. , Kennedy Joseph P. 
Published: April 2003

AbstractThe effect of molecular variables upon the dynamic viscoelastic behavior of solutions of sulfonated polyisobutylene telechelic ionomers in nonpolar solvents has been investigated. Intermolecular association of the ionic end groups in nonpolar media results in the formation of a transient ionic network which displays a viscous response at low frequencies and an elastic response at high frequencies. The frequency of the transition from viscous behavior to elastic behavior, as well as the plateau storage modulus, is dependent upon molecular variables such as architecture, molecular weight, neutralizing cation, and extent of neutralization. Variables which affect the strength of the ionic interactions, such as temperature and the type of solvent, also influence the viscoelastic response. Solutions of ionomers neutralized with cations of Groups IA and IIA, such as potassium and calcium, behave elastically over most of the experimentally accessible frequency range, while those neutralized with transition metals, such as zinc, display viscous flow over a rather wide range at low frequencies. As in previous studies of dilute solution viscosity behavior, the threearm star trifunctional species was found to form a more extensive network in nonpolar solvents than the linear difunctional species at equivalent concentrations. The failure of time–temperature superposition indicates that these solutions are thermoheologically complex.
Transport of methylene chloride in poly(aryl‐ether‐ether‐ketone) (PEEK) resin and composite during alternate sorption/desorption cycles
Authors: Grayson Michael A. , Wolf Clarence J. 
Published: April 2003

AbstractThe transport of methylene chloride into PEEK resin systems following six successive sorption/desorption cycles was investigated. The sorption and desorption processes in neat PEEK with different morphologies and with varying degrees of crystallinity (from 1 to 29%) were compared to chopped‐carbon‐fiber and carbon‐fiber‐laminate composites. The amount of methylene chloride sorbed during an 80‐min immersion varied from less than 1 wt % in the composites to 37 wt % in the amorphous neat PEEK. During each cycle the solvent was desorbed at 95°C for 338 h. With the exception of the laminate, the sorption/desorption process is essentially independent of cycling. Furthermore, when the desorption processes are viewed in normalized form, i.e., fractional weight loss as a function of time, the desorption appears identical in all samples investigated. Although the maximum amount of solvent retained by the laminate was small, less than 0.1 wt % after the first cycle, it did increase to almost 0.15 wt % after 5 cycles.
Polyurethane–polypropylene blends
Authors: Petrović Zoran S. , Budinski‐Simendić Jaroslava , Divjaković Vladimir 
Published: April 2003

AbstractFive series of blends were obtained by mixing five polyurethanes (PUR), based on poly‐propyleneoxide, MDI, and butanediol, with polypropylene (PP). The structure of PUR was varied by varying soft segment length (MW = 1000 and 2000) and soft segment concentration (50, 60, and 70%). It has been shown that interaction between PUR and PP was better in the case of PUR with the polyol of MW = 1000. The addition of lower molecular weight PUR produced an easy flowing material in the molten state, comparable with the “control rheology PP.” The morphology of the blends changed with PUR concentration. At 30% PUR the dispersed phase tended to agglomerate in the form of long cylinders. Mechanical properties generally were affected by the change of morphology.
Transparency of recycled polypropylene film
Authors: Shibayama Mitsuhiro , Imamura Ken‐Ichiro , Katoh Kuniyasu , Nomura Shunji 
Published: April 2003

AbstractTurbidity of quenched polypropylene films was measured as a function of the film thickness and number of times film was recycled. Turbidity τ is defined by τ = (1/d) ln (Io/It), where Io and It are the intensity of the incident and transmitted lights, respectively, and d is the thickness of the sample. We assume here that most of the attenuation of light is due to scattering from superstructure in the film, such as spherulites, since no characteristic absorption bands are present in the wavelength region studied in this work. Turbidity varied sigmoidally with film thickness. It remained constant when the film thickness was lower than ca. 400 μm and then increased with film thickness and reached a plateau around 800 μm. When the film preparation was repeated, turbidity increased exponentially with the number of recycles. The spherulite size, however, was an invariant against the number of recycles and was dependent upon film thickness. The variation of turbidity with film thickness and the number of recycles is discussed.
Polymer–surfactant interactions in graft copolymer solutions
Authors: Steiner Carol A. 
Published: April 2003

AbstractGraft copolymers composed of water‐soluble cellulosic backbones and > 0.4% (by weight) alkyl grafts are insoluble in water but soluble in surfactant solutions. Studies of the bulk viscosity and stability of polymer‐surfactant solutions at 49°C indicate that the mechanism for solubilization of the polymer is the incorporation of the alkyl side chains into surfactant micelles. The tendency for side chains to combine with micelles appears to depend at least in part on the geometry of the surfactant tail group such that surfactants containing straight‐chain tail groups solubilize alkyl side chains more readily than olefinic surfactants. The presence of small solutes near the surface of the micelle also inhibits incorporation of side chains from the polymer. Unsolubilized side chains remain in the aqueous phase of the solution, where they form thermally unstable intermolecular aggregates.
Isothermal sorption from finite baths: Effect of the boundary layer on sorption of diffusants by solids of various geometrical shapes
Authors: Etters J. N. 
Published: April 2003

AbstractThe literature reveals no equation that expresses the influence of the diffusional boundary layer on diffusion‐controlled sorption of dyes or other material by polymeric substrates from finite baths. In view of this mathematical void, a technique is proposed that approximates dimensionless sorption time as a function of fractional equilibrium uptake of diffusant by polymer, dimensionless dye bath exhaustion, and dimensionless boundary layer. The computational technique is based on relationships found in transitional kinetics and is shown to be applicable for sorption systems involving polymeric material of different geometrical shapes. To illustrate the technique, dimensionless half‐times of sorption are computed for the case of diffusant uptake by a cylinder.
Bench‐scale and pilot plant preparation of chemically modified polyester resins
Authors: Dairanieh Issam S. , Rasoul Firas A. 
Published: April 2003

AbstractThe laboratory preparation procedure of a recently developed unsaturated polyester resin was followed to prepare the resin on a large scale (10‐ and 200‐L pilot plant reactors). The process heating rate, reaction temperature, and agitator tip speed were kept constant on scale‐up. The resin was successfully reproduced and its properties were unchanged upon scale‐up. The effects of reaction temperature and inert gas flow rate on the polyesterification reaction rate were investigated. It was found that a 10°C increase in temperature or a 50% increase in the gas flow rate results in a 50% increase in the reaction rate.
A scheme for phase stability in liquid crystal polymers
Authors: Keller A. , Ungar G. 
Published: April 2003

AbstractIt is shown that conditions for realizing mesomorphic states in polymers are readily expressed in terms of the relative thermodynamic stabilities of the crystalline, liquid crystalline, and liquid phases. The simple scheme presented here has the merit of providing: (i) a unifying perspective over a wide range of mesophase behaviour that otherwise may be considered in isolation as disconnected occurrences, and (ii) a signpost for purposeful attainment (or enhancement) of the mesomorphic state also in the case of systems that are not normally considered liquid crystal forming. Examples are quoted from a range of materials, most comprehensively from polyethylene, bringing together diverse past and some rather striking new observations illustrating the validity and usefulness of the scheme.
Electrical conductivity of poly(2‐ethynylthiophene) and poly(2‐ethynylfuran) doped with electron acceptors
Authors: Gal Yeong Soon , Jung Bal , Choi Sam Kwon 
Published: April 2003

AbstractThe electrical conductivity of poly(2‐ethynylthiophene) (P2ET) and poly(2‐ethynylfuran) (P2EF) doped with electron acceptors such as iodine, bromine, and ferric chloride was investigated. The maximum electrical conductivities of P2ET and P2EF doped with iodine were 3 × 10−4 Ω−1 cm−1 and 5 × 10−3 Ω−1 cm−1, respectively. The electrical conductivity was nearly independent with increasing molecular weight. The spectral measurements such as UV‐visible, infrared, electron paramagnetic resonance, thermogravimetric analysis, and X‐ray diffraction were also carried out.
Tensile drawing behaviour of polyethylene terephthalate
Authors: Long S. D. , Ward I. M. 
Published: April 2003

AbstractA wide range of polyethylene terephthalate fibres was prepared by melt spinning to different degrees of molecular orientation. The tensile drawing behaviour of these fibers was then studied, either by drawing over a heated cylinder at 85°C or by drawing over both a heated cylinder and a plate at 180°C. The mechanical properties and structure of the subsequent drawn fibres are discussed in terms of the network draw ratio, determined by matching true stress–strain curves for the drawn and initial melt spun fibres. It is shown that this procedure provides valuable insight into subtle differences in properties and structure that can arise from differences in processing routes.
Fluorine‐containing optical adhesives for optical communications systems
Authors: Maruno T. , Nakamura K. 
Published: April 2003

AbstractFluroinated epoxy resin adhesives containing diglycidylether of bisphenol AF (DGEBAF) with a fluorine content of 25.7 wt % are developed for fabrication of optical communications devices. These adhesives, formulated with a diluent of butanediol diglycidylether (BDDG) and a curing agent of polyether polyamine (Q694), can be cured at a curing temperature as low as 65°C and exhibit high transparency of more than 80% in the wavelength range of 0.5–1.3 μm. Moreover, they significantly reduce return loss at optical‐glass/adhesive interfaces because of the low refractive indices of ca. 1.52 and also improve heat durability of optical devices. They are successfully applied to submarine optical fiber transmission system.
Photoinitiated graft copolymerization of hydroxyethyl methacrylate onto cotton cellulose
Authors: Shukla S. R. , Rao G. V. Gopala , Athalye A. R. 
Published: April 2003

AbstractThe photoinitiated graft copolymerization of hydroxyethyl methacrylate (HEMA) onto cotton cellulose was studied using uranyl nitrate (UN) and ceric ammonium nitrate (CAN) photoinitiators. Optimization of various parameters of the graft‐copolymerization reaction viz., time, temperature, initiator, and monomer concentration, was carried out. The optimized conditions of grafting were employed to cotton samples swollen in zinc chloride as well as sodium hydroxide. Graft add‐on was found to be dependent on the nature of substrate and the concentrations of monomer and photoinitiator. UN was found to be the better photoinitiator, giving higher grafting with HEMA. The grafted samples showed initially decrease and then marginal increase in the moisture regain with increase in graft add‐on. The dye uptake of both direct and reactive dyes decreased with increase in graft add‐on.
Ultracentrifugal studies of the degradation of a fracturing fluid polymer: Hydroxypropyl guar
Authors: Budd Peter M. , Chakrabarti Sumana 
Published: April 2003

AbstractUltracentrifugal techniques have been employed to investigate the degradation of hydroxypropyl guar (HPG) solutions, and of gels formed with a delayed zirconium cross‐linker, by ammonium persulphate at 90°C. Molecular weights, M, for various samples of degraded polymer were determined by sedimentation/diffusion, and an empirical relationship was established between M and the sedimentation coefficient at a single, low concentration. This enabled the straightforward determination of M as functions of persulphate concentration, cross‐linker concentration, and time at temperature. It was shown that large decreases in M occur within the first hour at temperature, but that complete degradation is not achieved. It was further shown that, when a delayed zirconium cross‐linker is used, degradation may be less effective when gels are formed and degraded at high shear rates.
Surface and interfacial FTIR spectroscopic studies of latexes. I. Surfactant–copolymer interactions
Authors: Evanson Kevin W. , Urban Marek W. 
Published: April 2003

AbstractMolecular level interactions between surfactants and copolymers as well as transient effects during latex film formation play an important role in latex technology. Photoacoustic (PA) and attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of interactions between sodium dioctylsulfosuccinate and ethyl acrylate/methacrylic acid (SDOSS/EA/MAA) copolymer in latex films at both the film–air and film–substrate interfaces. It is shown that the splitting of the asymmetric SO stretching normal vibrations of the SO groups in the presence of Na+ counterions occurs only when weak COOH acid groups of latex are present. The absence of the COOH groups either by neutralization of latex or intentional synthesis eliminates the SO···HO associations that are the primary source of the symmetry changes resulting in the splitting of the SO symmetric mode at 1050 cm−1 to two bands at 1046 and 1056 cm−1.
Amino acids as substrates for preparation of monomers with imide rings
Authors: Orzeszko Andrzej 
Published: April 2003

AbstractThe reaction of pyromellitic anhydride PMDA with some amino acids lead to monomers, which were used to synthesize new polymers. Application to glycine, D,L‐alanine and β‐alanine gave three bis‐acid chlorides. These are able to condense with glycols and diamines to yield a series of new copolyimides. Amino acids of two carboxylic groups D,L‐glutamic acid and D,L‐aspartic acid gave, in reaction with PMDA, two similar dianhydrides (4) and (5). However, the condensation with aromatic amines lead to two different compounds. It was proved that, under the conditions studied, formation of hexa‐membered imide rings was impossible while penta‐membered imides formed without difficulty. Thermogravimetric analyses of these polymers were also carried out.