bluuebunny/crossref_metadata_2025 huggingface dataset:
On‐line monitoring of polymer quality in a batch polymerization reactor
Authors: Ponnuswamy S. , Shah S. L. , Kiparissides C.
Published: April 2003

A novel experimental reactor system has been designed to study a variety of problems related to on‐line measurements and computer control of batch polymerization reactors. A number of measuring devices such as densitometer, viscometer, size exclusion chromatograph, and torquemeter have been put on‐line to a batch reactor and interfaced to a real time computer to monitor monomer conversion and molecular weight during polymerization. A new feature of the experimental setup is its microprocessor‐based sampling system which automatically collects samples from the reactor and injects them into the SEC analyzer. Computer software has been developed for on‐line acquisition and processing of SEC data. This work demonstrates the feasibility of on‐line measurement of monomer conversion and molecular weight. Furthermore, it presents a comparative study of some common techniques employed for off‐and on‐line measurement of polymer quality.
Crystallization kinetics of polyaryl ether ketones
Authors: Jog J. P. , Nadkarnit V. M.
Published: April 2003

The crystallization kinetics of a grade of polyaryl ether ketone has been investigated over a temperature range of 295–315°c by differential scanning calorimetry.The results of the present investigation are compared with other members of the polyaryl ether ketone family in the context of the effect of chemical structure on the crystallizability of the polymers. It is concluded that the crystallizability is reduced with increasing amount of ketone linkages in the chain, and therefore the optimum molding conditions for different grades of polyaryl ether ketones will be different.
Sorption and permeation behavior of water vapor and carbon dioxide gas through ethylene ionomer membranes
Authors: Itoh Ken‐Ichiro , Tsujita Yoshiharu , Takizawa Akira , Kinoshita Takatoshi
Published: April 2003

Sorption and permeation of water vapor and carbon dioxide gas through ethylene ionomer membranes were studied as a function of pressure. Water sorption increased with an increase of the acid content and especially degree of neutralization of ethylene ionomers. The sodium salt ionomer enhanced water sorption compared to the zinc salt ionomer. However, there was no remarkable difference of permeability coefficient of water vapor through the sodium and zinc ionomer membranes. Diffusion coefficient of the sodium salt ionomer is one order smaller than that of zinc salt ionomer, corresponding to an immobilized water structure in the sodium salt ionomer. Differential scanning calorimetry studies on water sorbed to membrane manifested that water sorbed was almost nonfreezable. Sorption of carbon dioxide gas in ethylene ionomers was a dual‐mode type. The pressure dependence of permeability coefficient of carbon dioxide gas was interpreted in terms of a partial immobilization model, independent of the kind of the metal salt in ethylene ionomer.
Factors affecting improvement in the flexural modulus of polyacrylic acid‐modified crystalline films
Authors: Sugama T. , Kukacka L. E. , Carciello N. , Warren J. B.
Published: April 2003

When high‐molecular weight polyacrylic acid (PAA) macromolecules are incorporated into phosphating solutions, they significantly increase the stiffness and ductility of zinc phosphate conversion crystal films deposited on metal substrate surfaces. The degree of improvement in these mechanical properties depends primarily on the thickness and fineness of the highly dense PAA‐complexed zinc phosphate crystals that are formed. The presence of this complexed PAA polymer at the outermost surface sites on the crystal layer plays an essential role in promoting adhesion with polymeric topcoats by the formation of polymer—polymer chemical bonds. The use of low‐molecular weight PAA results in a poor interfacial adhesion because of a high degree of alternation in chain conformation caused by charge‐transfer reactions between the proton‐donating COOH groups and the nucleophilic Zn2+ ions in the acidic aqueous medium. In addition, the protective polymer topcoat overlayed on the complex precoat surfaces increases the flexibility of the crystalline precoat itself. The most important factors controlling the flexibility of the precoat were low elastic modulus, high tensile strength, and elongation of the topcoat systems. These characteristics are more important than the magnitude of interfacial adhesive bonds at topcoat/precoat joints.
Effect of ionizing radiation on styrene/acrylonitrile copolymer hollow fiber membranes
Authors: Fritzsche A. Keith
Published: April 2003

A thin layer of highly permeable, nonselective polymer is applied to the surface of an asymmetric membrane to reduce permeability through the membrane pores and defects and to render permeation through the matrix predominant. In environments which contain active moieties, the coating may be swollen and dissolved causing it to lose its effectiveness. The effects of irradiation to induce crosslinking between the hollow fiber membrane and the coating were studied. Fibers were irradiated both before and after coating with polydimethylsiloxane. Radiation dosages at 10, 25, and 50 Mrads were used. The increased stabilities of the crosslinked coating and substrate were reflected by the higher retention of H2/CH4 separation factor after exposure to a solvent (i.e., isopentane) which dissolves the coating. The results also suggest that ionizing radiation also alters the structure and morphology of the dense selective layer on the surface of the styrene/acrylonitrile copolymer hollow fiber.
Degradation of polymers during aerosol formation from antimisting polymer solutions
Authors: Ilano Arron L. , Williams Michael C. , Grens Edward A.
Published: April 2003

Degradation of polyisobutylenes as a consequence of spraying jet‐fuel solutions of these polymers was studied as a function of polymer molecular weight and concentration and the spray conditions. Assessment of the degradation was made by measuring the maximum ductless siphon height h* for sprayed samples and comparing this with prespray values. Two polymers, L‐160 from Exxon and B‐288 from BASF (Mv = 4.1× 106 and 11.9 × 106), were studied to concentrations of 3000 and 2000 ppm, respectively. Degradation was found to be extremely sensitive to the air speed used in wind‐shear spraying, above a critical value of approximately 30–40 m/s. At the highest air speed employed, 135 m/s, degradation was so severe that h* values were reduced nearly to Newtonian (solvent) values, for all concentrations of both polymer additives. The implications of these results are important for designing effective antimisting fluids.
Cross‐linking of amidated polybutadiene with resole. II.
Authors: Hara Hajime , Araki Yoshihiko , Orii Shingo
Published: April 2003

To prove the main cross‐linking reaction between amidated polybutadiene and resole, cross‐condensation reactions involving simple amide compounds and resole were examined. Amide compounds having both an amide group and a carboxylic acid group inhibited the self‐condensation of resole itself. The cross‐condensation products obtained from succinamic acid and 2‐methylolphenol were separated using a preparative chromatography method to identify the cross‐condensed products in which the main products were cross‐condensed oligomers having an imide linkage. A cross‐condensation scheme was proposed, and it was concluded that the main cross‐linking reaction between amidated polybutadiene and resole also followed the same scheme.
Determination of the molecular weight between cross‐links of elastomeric stocks by tensile retraction measurements. II. Polyurethanes
Authors: Hergenrother W. L.
Published: April 2003

Tensile retraction measurements of Mc were made on a variety of polyurethanes or polyurethane‐ureas. These samples were prepared using a number of prepolymer MW and functionalities. In addition, the stoichiometry of the cure was allowed to range widely. In all cases, excellent linear correlation coefficients were obtained between the Mc and the Amax of the test. The slope and Mr (the value of Mc extrapolated to Amax = 1) determined from this was used to characterize the polymer. These data allowed the determination of χ for each of the different systems such that comparable values of Mc could be measured by swelling. Identical formulations cured at different temperatures were shown to have measurable differences in Mc, slope, and percentage set. These variations appear to relate to the perfection of the network and morphology of the hard domains.
The effects of a synergistic molybdenum–copper smoke retarder additive during the pyrolysis and combustion of rigid poly(vinyl chloride) compounds
Authors: Kroenke William J. , Lattimer Robert P.
Published: April 2003

The addition of an effective transition metal‐based smoke retarder to rigid poly(vinyl chloride) (PVC) has three general effects during combustion and inert atmosphere pyrolysis: (1) smoke formation is reduced; (2) char formation is enhanced; and (3) volatile aromatic pyrolyzate formation is reduced while aliphatic pyrolyzate formation is enhanced. A very efficient molybdenum—copper smoke retarder additive has been developed for PVC. It consists of an equal weight mixture of melaminium beta‐octamolybdate and copper(II) oxalate. This combination is synergistic in reducing smoke during the combustion of PVC, i.e., the mixture is more effective than either of the two ingredients used individually at the same concentration as the mixture. The molybdenum—copper system reduced smoke effectively in three rigid PVC compounds, two of which resemble commercial formulations. The combustibility and pyrolysis effects of this molybdenum—copper additive can be interpreted in terms of an “early cross‐linking” mechanism of smoke retardation in PVC. In this mechanism the metal smoke retarder works primarily by catalytically promoting early crosslinking of decomposing PVC chains to yield char as a residue.
The influence of annealing on the thermal properties of poly(ethylene terephthalate) fibers I. The heat capacity of annealed PET fibers
Authors: Urbanczyk G. W. , Michalak G.
Published: April 2003

The influence of annealing of PET fibers on their specific heat capacity 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 obtained results give evidence that three temperature intervals of annealing may be distinguished. The ascertained variation of cp has been discussed on the basis of established morphological and fine structure changes in the fibers caused by the applied annealing.
Photocrosslinking of chlorinated polydimethylsiloxanes
Authors: Inoue Hiroshi , Kohama Shigemi
Published: April 2003

Photocrosslinking behavior of chlorinated polydimethylsiloxanes (C‐PDMS) has been studied. It was found that the viscous C‐PDMS were readily crosslinking to form the rubberlike materials on irradiation from a high pressure mercury lamp. The crosslinking mechanism was proposed on the basis of infrared spectroscopy. It was suggested that the photolysis of the carbon—chlorine bond induced by the ultraviolet irradiation is a primary step for crosslinking, and is followed by mutual combination of SiCH2· radicals, eventually, to form the crosslinked C‐PDMS. The effect of halogens and atmosphere on the crosslinking was also discussed.
Effect of types of carbon black and cure conditions on dynamic mechanical properties of elastomers
Authors: Trexler Harold E. , Lee Michael C. H.
Published: April 2003

The dynamic mechanical properties of natural rubber and bromobutyl rubber (used in automotive suspension parts) were investigated to determine the effect of particle size of carbon black filler and state of cure of the rubber matrix. The results indicate that state of cure has little effect on storage modulus (hardness and stiffness). However, elastomers with a desirable storage modulus, with low sensitivity to temperature change, can be developed using a filler with a small particle size.
The adhesive properties of hydantoin vinyl ether polymers
Authors: Eldin Sameer H.
Published: April 2003

The hydantion vinyl ether polymers are alternating copolymers of 3‐vinyloxyethyl‐5,5‐dimethylhydantion (HVE) and maleic anhydride (MA). The adhesive properties of HVE/MA and structurally related polyvinyl pyrrolidone (PVP) and methylvinylether/maleic anhydride (MVE/MA) polymers were compared on an approximately 1:1 specific viscosity basis. Lap shear strength measurements showed approximately 10:1 and 4:1 ratios in favor of the HVE/MA polymers as compared to PVP and MVE/MA, respectively. These differences are possibly due to the higher cohesive strength of the HVE/MA repeating unit and to the fact that this polymer would appear to contain more structural elements liable to make physical and chemical contributions to the interfacial attachment strength. Based on these preliminary results, HVE/MA and MVE/MA polymers with identical specific viscosities were applied to carbon pitch fiber via electrodeposition. Using the standard MY 720/DDS epoxy laminating system for advanced composite applications 36% and 13% improvements in interlaminar shear strength were observed for an add‐on of 2%.
Effect of metal halides on thermal, mechanical, and electrical properties of polypyromellitimide films
Authors: Varma Indra K. , Saxena Sneh , Tripathi Anita , Goel T. C. , Varma D. S.
Published: April 2003

This paper describes the effect of metal halides (Co2+, Sn2+, and Hg2+) on the properties of polyimides. Low temperature, solution polycondensation reaction of pyromellitic dianhydride and 4,4′‐diaminodiphenyl ether was used for preparation of a poly(amide‐acid) solution in dimethylformamide ([η] = 2.0 dL/g). Films containing 1% (w/w) of cobalt (II) chloride, tin (II) chloride, and mercury (II) chloride were prepared by solution casting of poly(amide‐acid) from the DMF solution. Cyclodehydration to polyimide was done by heating the films in nitrogen atmosphere for one hour each at 100°, 200°, and 250°C. The color of the films depended on the dopant and was yellow (HgCl2 or SnCl2) or green (CoCl2) Higher percentage weight loss was observed in doped films in nitrogen atmosphere in the temperature range of 250–400°C. No significant difference in thermal behavior of doped and undoped films was observed above 500°C. Doping reduced the tensile strength of polyimide films, maximum reduction was observed in CoCl2‐doped film. The electrical conductivity of polyimide films as a function of temperature and field was studied. Undoped polyimide showed ohmic behavior up to 150°C. In doped films at lower voltages Poole‐Frenkel mechanism was operative, while at high voltages Richardson‐Schottky's mechanism was operative. Dielectric relaxation in polyimide films was also studied.
Chemical modification of polyester fiber surfaces by amination reactions with multifunctional amines
Authors: Avny Yair , Rebenfeld Ludwig
Published: April 2003

The feasibility of incorporating amine groups into the surface of polyester (PET) fibers by reaction with multifunctional amines was investigated. Reactions of diethylenetriamine (DETA), trethylenetetramine (TETTA), and tetraethylenepentamine (TTEPA) with PET monofilaments and with a multifilament yarn were studied. Microspectrophotometric examination of aminated fibers stained with an acid dye at low pH revealed the location and concentration of amine groups. Amination could be confined to the periphery and was found to be uniform on the fiber surface. The rate of the reaction, as revealed by acid dye staining, was characterized by an induction period followed by an autoaccelerated stage. Extent of incorporation of amine groups was found to be similar for the three amines. There is a significant improvement in water wettability due to surface amination, and the interfacial shear strength of TTEPA‐treated PET monofilaments embedded in an epoxy resin matrix was almost doubled. As the amination reaction proceeds, there is a weakening of the reacted zone in the PET due to chain scission leading to a decrease in the interfacial shear strength. Scanning electron microscopy (SEM) studies revealed that failure occurred within the filament most probably between the reacted and unreacted zones. The tensile properties of the TTEPA‐treated PET filaments were hardly affected at the investigated extents of amination.
Plasma, polymerization of ethane and some properties of PP ethane as a protective coat
Authors: Akovali Guneri
Published: April 2003

The structure of plasma polymers of ethane prepared by use of 13.56 MHz radiofrequency discharge in a tubular reactor are examined. The dependency of rate of deposition on power and on tube pressure at a fixed flow rate are presented. The plasma polymer prepared is tested for its performance as a protective coat on NaCl optical components for use in CO2 laser windows. Absorbance, at and around 10.6 μm, water‐vapor transmission, and scratch‐resistance tests are done.
Synthesis of polystyrenes having 2‐pyridylthio group and their use as phase transfer catalysts for the reduction of carbonyl compounds by sodium borohydride
Authors: Kondo Shuji , Nakanishi Minoru , Yamane Kazuyuki , Horibe Atsushi , Tsuda Kazuichi
Published: April 2003

p‐(2‐Pyridylthiomethyl)styrene (PTMS) and p‐(2‐pyridylthioethyl)styrene (PTES) were prepared from the reactions of 2‐pyridinethiol with p‐chloromethylstyrene and with p‐bromoethylstyrene, respectively. These monomers are readily polymerized in the presence of AIBN. From the copolymerization of PTMS with styrene, QPTMS = 1.19 and ePTMS = 0.24 were obtained. The resulting polymers can extract alkali metal ions such as sodium and potassium cations. The extraction ability increases with increasing the density of active sites in polymers. Further these polymers serve as phase transfer catalysts for the reduction of carbonyl compounds by sodium borohydride.
Use of a sequential extraction technique to determine the MWD of bulk UHMWPE
Authors: Kusy R. P. , Whitley J. Q.
Published: April 2003

The molecular weight distribution (MWD) of bulk ultrahigh molecular weight polyethylene (UHMWPE) was determined by an increasing temperature sequential extraction technique. Using decahydronapthalene (decalin) as the solvent, 5 g samples of UHMWPE were fractionated stepwise from room temperature to 190°C in 10°C increments. Results via high temperature capillary viscometry show that intrinsic viscosity ([η]) ranges from 12.0 to 37.0 dL/g or that the viscosity average molecular weight (M̄v) ranges from approximately 1.6 to 7.4 × 106. When the integral distribution is plotted against M̄v on logarithmic probability graph paper, a straight line (i.e., a Wesslau distribution) results. Although the present methodology is tedious, many previous problems which have led to degradation are overcome by this technique.
Electrical and other properties of mutual radiation‐induced methacrylic acid grafted polyethylene films
Authors: Omichi H. , Chundury D. , Stannett V. T.
Published: April 2003

The radiation‐induced grafting of methacrylic acid on to polyethylene films was applied to the synthesis of ion‐exchange membranes. The grafting yield increased at first then decreased with the increase in the irradiation dose. The surface area, thickness, volume, and the water uptake of the grafted film increased linearly with the increase in grafting yield. The distribution pattern of carboxyl groups of graft chains in the direction of film thickness followed by EPMA line profiles of potassium which combined with carboxyl groups showed that a homogeneous distribution was not obtained until the grafting yield was more than 10%. When DC current was supplied to the membrane in NaOH solution, the reciprocal of the electric resistance increased with the increase in NaOH concentration. The specific electric resistance decreased exponentially with the increase in the content of ionic functional groups in the membrane. The steady state concentration of Na+ in catholyte and the current efficiency were ca. 15 and 20%, respectively.
Thermal analyses of flame‐retardant twills containing cotton, polyester and wool
Authors: Trask Brenda J. , Beninate John V.
Published: April 2003

Medium weight twill fabrics constructed from cotton and cotton blended with polyester and/or wool were analyzed under nitrogen by three thermoanalytical techniques. Fabrics were tested both before and after treatment with [tetrakis(hydroxymethyl)phosphonium] sulfate (THPS), urea, and trimethylolmelamine. The presence of all fibers was distinguishable in differential scanning calorimetric analysis (DSC) of untreated fabrics; the relative positions of the endothermic, decomposition peak temperatures were only slightly changed. After flame‐retardant (FR) treatment, the blended cotton and wool fibers were altered. Both fibers decomposed as exotherms during DSC analysis. These data supported earlier microscopical, X‐ray evidence that wool fibers were actually reacting with the FR treatment. The two DSC peaks for polyester polymer melting and decomposing remained unaffected by either blending with other fibers or the presence of the FR finish on the fabric. There was excellent agreement between DSC peak temperatures and the temperature of maximum rate of weight loss obtained from thermogravimetric analysis (TGA). Blending cotton with either of these fibers increased the residue measured after TGA. The increased residue correlated with increased flame resistance as measured by the 45° angle, edge‐ignition burning rate test.
Fourier transform infrared studies on the thermal degradation of polyvinylimidazoles: Part I
Authors: Eng Frederick P. , Ishida Hatsuo
Published: April 2003

Thermal degradation of polyvinylimidazoles on potassium bromide plate has been studied. At 300°C heat treatment, the occurrence of oxidation and dehydrogenation leads to the formation of saturated ketones and unconjugated CC bonds in the polymer backbone, respectively. The combination of the two types of reactions also yields α,β‐unsaturated keto compounds. Then at prolonged heat treatment at 300°C, cleavage of imidazole rings also occurs and α,β‐unsaturated cyano structures are formed. At 400°C, a new class of compound, carbodiimides, is being produced while the amount of the α,β‐unsaturated cyano compounds is greatly reduced. Similar to polyacrylonitrile, ladder‐type structures for degraded PVI(1) and PVI(4) are proposed probable.
Fourier transform infrared studies on the thermal degradation of polyvinylimidazoles. Part II
Authors: Eng Frederick P. , Ishida Hatsuo
Published: April 2003

Oxidative thermal degradation of polyvinylimidazoles on copper have been studied. Degraded products include olefinic, saturated, and α,β‐unsaturated ketones, α,β‐unsaturated and β‐iminonitriles, CN conjugated and NHCC components. At 150°C, the rate of degradation of the polymers is relatively slow. For PVI(1), approximately 50% of the polymer remained nonoxidized after 64 h of heating, whereas 80% of PVI(4) remained nonoxidized after 47 h of heat treatment. At 210°C, the degradation mechanisms involved three stages, with the duration of each stage quite different between the two polymers. No degradation of polyvinylimidazoles is observed in vacuum initially at 400°C. Prolonged heat treatment leads to evaporation of residual water, further complex formation, and, finally, evaporation of the polymer films.
Effects of polar groups of polymer matrix on reinforcement‐matrix interaction in kevlar fiber‐reinforced composites
Authors: Kodama Minekazu , Karino Isamu
Published: April 2003

In order to investigate the interaction between the polar groups of reinforcement and matrix in polymer composite, mechanical properties were studied for the Kevlar fiber‐reinforced composites (Kevlar is a registered trademark of E. I. duPont de Nemours Co. Inc.), in which the kind and fraction of polar components in matrix were varied using blended polymers. For the composites comprised of polymethyl methacrylate and poly(hydroxypropyl ether of bisphenol A) as the matrix, a subtransition, which can be ascribed to the interphase formed on the reinforcement surface by a strong interaction between reinforcement and matrix, appears at a temperature above the primary transition on the E″ versus temperature curves. Such a subtransition is obscured or diminished accompanying the decrease in fraction of the polar components in the matrix. The fiber efficiency factors for strength are also decreased with a decrease in the fraction of the polar components. These results imply that the reinforcement‐matrix interaction is affected depending on the fraction of the polar components in matrix.

For the composite comprised of blending the two polar components as the matrix, each component can contribute to the interaction with the reinforcement.

The results obtained from the Fourier transform infrared spectroscopy on the matrix polymer‐coated Kevlar cloth do not contradict those obtained by studying the mechanical properties.
Synthetic resins: II: Preparation and characterization of resins prepared from aminoacetophenone
Authors: Patra Santosini , Lenka Subasini , Nayak Padma L.
Published: April 2003

A number of resins were prepared by condensing m‐aminoacetophenone with substituted aromatic compounds and formaldehyde in the presence of acids and bases as catalyst. The resins were characterized by infrared spectra. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental value. The bacteriocidal properties of the resins have been studied.
Beta dielectric dispersion in natural rubber latex
Authors: Laogun Abimbola A.
Published: April 2003

The dielectric dispersion of natural rubber latex has been investigated over a frequency range of 0.1–100 MHz and at six temperatures from 20° to 70°C. A computer analysis of the dispersion data showed that the Cole–Cole structural equation gave a better fit than the Debye. The large values of the Cole‐Cole α spread parameter suggest heterogeneity of structure in rubber latex. The latex viscosity and the relaxation time were both found to be influenced by changes in temperature. Application of the Arrhenius temperature equation to the data yielded a mean activation enthalpy of 32.6 ± 2.8 kJ/mol for the relaxation process.
Reactivity of epoxy resin in dispersed dicyandiamide system and dynamic viscoelasticity of the resulting product
Authors: Muroi Souichi , Ishimura Hidekazu , Outsuka Masahiko
Published: April 2003

A study was made on the curing reaction, leading to a cross‐linked network, of bisphenol A diglycidyl either in a dispersed dicyandiamide (DICY) system containing benzyl dimethylamine accelerator and on the dynamic viscoelasticity of the resulting product as related to the DICY particle size (Ds), and compared with a dissolved DICY system. The curing reaction rate varied inversely with logarithmic Ds and directly with the total surface area of the DICY particles, and the finally attainable extent of reaction of the epoxide group decreased with increasing Ds. Activation energy ranged from 14 to 17 kcal/mole depending slightly on Ds. The dynamic viscoelasticity of the cured product was also affected greatly by Ds. Cured product from the system with a 3 μm DICY displayed only a primary transition peak around 180°C in plots of viscoelastic decrement as a function of temperature. With DICY of larger than 10 μm Ds, the number of transition peaks increased to two or three, with a primary peak, a secondary peak around 140μC, and a tertiary peak around 90μC. The relative height of the secondary or tertiary peak increased with increasing Ds. The reaction of the dissolved DICY system proceeded at much the same rate as the 25 μm Ds system, but yielded a cured product with viscoelasticity similar to that of the 3 μm Ds system.
Thermosensitive dielectric properties in polyamide–phenol hybrid compounds and their application to the temperature‐sensing wire
Authors: Kishimoto Yoshio , Hosaka Tomiharu , Shimotsuma Wataru
Published: April 2003

Thermosensitive dielectric properteis in polyamide–phenol hybrid compounds have been studied. The polyamide–phenol hybrid compounds are constituted of p‐hydroxybenzoate–formaldehyde condensation oligomer dispersed molecularly in nylon 12 and polyamide copolymer. These materials are less hygroscopic than nylon 12 which is the least hygroscopic among polyamide homopolymers. It will be because the phenol group coordinates to amide group as the less hygroscopic “pseudo‐water” instead of water. One of these materials has also shown an intrinsic hydrophobic effect of hydrogen bond segment due to the “hybrid effect” between polyamide and phenol. The thermosensitive dielectric properties are based on the temperature dependence of intermolecular hydrogen bond behaviors by amide and phenol groups, which have been discussed in relation with the molecular behaviors. The relationship with polarizations constituting dielectric constant and hydrogen bonding molecular segments, and ac hopping conduction behaviors by proton carriers have also been discussed. These materials are applied as a temperature‐sensing material in a flexible thermosensing heater wire, which has three functions, that is, thermosensing, heating, and fusing for safe in the case of an abnormal overheat. As the features for a sensing material, these materials show the humidity low‐dependence and highly thermal stability, and will be situated as one of the high‐performance sensing material useful for the electric warmer such as an electric blanket.
Chain extenders for polyester. II. Reactivities of carboxyl‐addition‐type chain extenders; bis cyclic‐imino‐ethers
Authors: Inata Hiroo , Matsumura Shunichi
Published: April 2003

The reaction behavior of such bis cyclic‐imino‐ethers as 2, 2′‐bis(2‐oxazoline), which had been proved in the previous paper to be an effective chain extender to couple carboxyl terminals of linear polyesters through addition reaction, has been studied to evaluate their practical applicability as the chain extenders for poly(ethylene terephthalate) and poly(butylene terephthalate). It has been observed that a wide range of excess use of 2,2′‐bis(2‐oxazoline) resulted in polyesters of almost similar molecular weight. In addition, when excess amounts of the chain extender were added and the reaction conditions were fixed, the ratio of the coupled carboxyl terminals to the initial carboxyl terminals became constant regardless of the initial molecular weight and carboxyl content (CV). The results indicate that the chain‐extended polyesters possess predetermined molecular weight and CV, both of which depend only on the molecular weight and CV of the initial polymers, and not on the amount of the chain extender added.
Effect of temperature of motionless air on the cure of vulcanizates after removal from the mold
Authors: Khouider A. , Vergnaud J. M.
Published: April 2003

This paper determines the increase in the state of cure through the rubber mass during the cooling period after the vulcanizate is removed from the mold. The problem is complicated because of the great number of parameters. Some of them, such as the dimension of sample, the state of cure through the rubber at the time of its removal from the mold, the nature of the fluid, its agitation and temperature, are of interest. This work is concerned with the study of the effect of the temperature of motionless air in which the vulcanizate is cooled. This parameter is important in increasing the state of cure. Although the problem is complicated, it has been resolved by using a model based on a numerical method of calculation with finite differences. This model takes into account not only heat transfer by conduction through the rubber and by convection through rubber‐air interface, but also the kinetics for heat evolved in the cure reaction.
Polymerization of olefins through heterogeneous catalysis—V. Gas‐liquid mass transfer limitations in liquid slurry reactors
Authors: Floyd S. , Hutchinson R. A. , Ray W. H.
Published: April 2003

Many processes for polymerization of olefins employ laboratory, pilot plant, or full‐scale liquid‐phase polymerization reactors with monomer introduced as a gas. Criteria for the presence of gas‐liquid mass transfer resistance in these systems are determined in terms of observed reaction rate or loading of a heterogeneous catalyst of given intrinsic activity. The effects of variables such as reactor size and configuration, temperature, and soluble polymer are also examined. The equilibrium monomer concentrations of ethylene in hexane and propylene in heptane are calculated through a modified Benedict‐Webb‐Rubin equation, and some calculations for ethylene‐propylene mixtures are tabulated. The general methodology for predicting gas‐liquid mass transfer resistance is readily extendible to copolymerization systems.
Blends containing polymers of epichlorohydrin and ethylene oxide. Part I: Polymethacrylates
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R.
Published: April 2003

The phase behavior of blends of various polymethacrylates with poly(epichlorohydrin) (PECH); poly(ethylene oxide) (PEO); and a copolymer of epichlorohydrin and ethylene oxide [P(ECH/EO)], was examined using differential scanning calorimetery (DSC), dynamic mechanical properties, and optical indications of phase separation on heating, namely lower critical solution temperature (LCST) behavior. Poly(methyl methacrylate) (PMMA), was shown to be miscible with PECH, PEO, and P(ECH/EO), while only PECH was found miscible with the higher polymethacrylates: poly(ethyl methacrylate), poly(n‐propyl methacrylate), poly(n‐butyl methacrylate), and poly(cyclohexyl methacrylate). However, even PECH was found to be only partially miscible with poly(isopropyl methacrylate). In many cases, unusually broad glass transitions were observed by DSC for blends which are believed to be the result of equilibrium composition fluctuations. All mixtures showed LCST behavior and based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. For PECH, it appears that the interaction with polymethacrylates decreases with increasing size of the alkyl pendant group, with poly(cyclohexyl methacrylate) being a possible exception. The interaction with PMMA is apparently about the same for PECH and PEO, but somewhat less for P(ECH/EO). The latter is consistent with an intrachain attraction of ECH and EO believed to exist. The reasons for similar interactions of PEO and PECH with PMMA are not understood; however, it is clear that the chlorine moiety of PECH is needed for miscibility with higher polymethacrylates.
Estimation on thermal conductivities of filled polymers
Authors: Agari Y. , Uno T.
Published: April 2003

A new thermal conduction model is proposed for filled polymer with particles, and predicted values by the new model are compared with experimental data. The model is fundamentally based on a generalization of parallel and series conduction models of composite, and further modified in taking into account that a random dispersion system is isotropic in thermal conduction. The following equation is derived from the new model; log λ = V · C2 · log λ2 + (1 − V) · log(C1 · λ1). Therefore, when thermal conductivities of polymer and particles (λ1, λ2) are known, thermal conductivity of the filled polymer (λ) can be estimated by the equation, with any volume content of particles (V). The new model was proved by experimental data for filled polyethylene, polystyrene and polyamide with graphite, copper, or Al2O3.
Drop sizes in turbulent liquid–liquid dispersions containing polymeric suspension stabilizers. I. The breakage mechanism
Authors: Borwankar R. P. , Chung S. I. , Wasan D. T.
Published: April 2003

Polymeric suspension stabilizers, when used in sufficient quantities, can stabilize liquid–liquid dispersions against coalescence. Experiments were performed using an in situ photomicrographic technique to determine the critical surface coverage of a hydroxypropyl methylcellulose product. The critical surface coverage was between 2.35 × 10−7 and 1.2 × 10−6 g/cm2. Noncoalescing dispersions can be prepared by using high concentrations of suspending agents so that the surface coverage is above the critical value. Such noncoalescing dispersions can be used to study the breakage mechanism even at high dispersed phase volume fractions. The study of the breakage mechanism reveals that the volume swept by the turbine impeller is applicable in calculating the power input per unit mass. The new correlation between the Sauter mean diameter and the extent of agitation under turbulent conditions that is found here is in fair agreement with those available in literature.
Role of polyacrylate starch copolymer in water sorption
Authors: Ziderman I. Irving , Belayche Janine
Published: April 2003

Water sorbence by saponified polyacrylonitrile‐grafted polysaccharides was studied in relation to practical end uses. Graft copolymers prepared from wheat flour, corn flour, cotton wool, and rayon fibers swelled to a gel, exhibiting a 10‐ to 20‐fold increase in sorbency over the starting materials. A further enhanced water capacity was obtained when homopolymer was not removed. Soaking the wheat flour copolymer in salts or dilute mineral acid nullified the enhanced water sorbence, which could be reversible restored by neutralization of acrylic acid functions with alkali. Swelling the copolymer in aqueous D‐glucose did not impair its water capacity. The mechanism of swelling to a gel appears to involve electrolyte osmotic pressure generated by a Donnan equilibrium. Grafting starch elevated its heat of water vaporization above that of pure water, and increased its capacity to absorb water from ethanol‐water vapor at 40° above that of native starch. At higher temperatures, however, the dehydrating capacity decreased to that of native flour.
Shear rheology of diluted solutions of high molecular weight cellulose
Authors: Navard P. , Haudin J. M. , Quenin I. , Peguy A.
Published: April 2003

A steady‐state and dynamical rheological study was performed with dilute solutions (1–4%) of high molecular weight cellulose (Mw = 350,000). The solutions are strongly viscoelastic. The steady‐state viscosity and the first normal stress difference have a power law dependence on the shear rate. The power law indices have the same dependence on temperature and concentration. These results as well as the correlation between the steady‐state viscosity and the real part of the complex viscosity are in good agreement with the Spriggs model. The 4% concentrated solution shows the beginning of a rubber‐like storage modulus plateau, suggesting the existence of an entanglement network.
The effect of electrolytes on direct dyes for cotton
Authors: Noah A. O. , Martins C. M. O. A. , Braimah J. A.
Published: April 2003

Electrolytes generally promote dyebath exhaustion when direct dyes are used for cellulosic fibers, but the extent with which they do so usually varies from one electrolyte to another. Two direct dyes with varying numbers of sulfonic acid groups were investigated. Cotton cellulose was dyed with these dyes using different electrolytes and a phosphate buffer system. The relationship between strength loss with increase in number of sulfonic acid groups was an obvious observation. Wash fastness results had indicated that the most important consideration is the molecular weight and the overall molecular architecture of the dye.
Studies on the reactions between thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole accelerator system in the early stage of vulcanization of NR
Authors: Datta Rabindra Nath , Das Prasanta Kumar , Basu Dipak Kumar
Published: April 2003

Investigations on the interactions of the synergistic pair of accelerators comprising of thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole have been carried out through hplc. N‐cyclopentamethylene thiocarbamyl‐N'‐oxydiethylene sulfenamide, N‐oxydiethylenethiocarbamyl‐N'‐cyclopentamethylene sulfenamide (OTCS), 2‐morpholinodithiobenzothiazole, and 2‐piperidinodithiobenzothiazole (PDB) have been selected as the reactants which, when suitably combined, provide most effective accelerator systems capable of generating heat and age resistant vulcanizates. The OTCS–PDB system has been found to yield vulcanizates which exhibit the greatest crosslink density, scorch safety, and highest modulus and tensile strength. An attempt has been made to explain the higher activity of the binary systems studied as compared to that obtained from comparable thiocarbamyl sulfenamide plus dibenzothiazyl disulfide system. Zin–dithiocarbamates have been found to influence the curing reactions depending upon the composition of the mixed accelerators. Cyclohexyl thiophthalimide, a versatile cure retarder, reacts with the accelerators to yield cyclohexyl thiomorpholine and cyclohexyl thiopiperidine, as the case may, which also have a profound effect upon cure retardation as noticed in the present investigation.
Copolymer analysis by UV spectroscopy
Authors: Ramelow Ulku , Baysal Bahattin M.
Published: April 2003

An extensive and detailed analysis of copolymers was made by developing a rapid spectrophotometric method. Successful analysis of composition in styrene‐p‐methoxystyrene, styrene‐p‐chlorostyrene, and styrene‐p‐fluorostyrene copolymers were performed by UV spectrometry. Their absorption bands were investigated either with respect to pure polystyrene or with respect to the homopolymer of the other constituent at the same wavelength. Attempts to analyze copolymers of styrene‐4‐vinylpyridine and styrene‐N‐vinylcarbazole by similar methods were unsuccessful.
Polyphenylquinoxalines containing alkylenedioxy groups
Authors: Havens S. J. , Harris F. W. , Hergenrother P. M.
Published: April 2003

A series of new polyphenylquinoxalines (PPQ) containing alkylenedioxy units within the backbone were prepared in high molecular weight forms (ηinh = 0.82–1.5 dL/g). The glass transition temperatures ranged between 203 and 241°C, decreasing with increasing length of the alkylenedioxy groups. Solution‐cast films gave tensile strength, tensile modulus, and elongation at room temperature as high as 14,400 psi, 378,000 psi, and 8.1%, respectively. The PPQ were readily compression molded to provide compact tension specimens that gave fracture energy (GIc) as high as 10.5 in. lb/in.2 Titanium to titanium tensile shear specimens provided average strengths of 4400 psi at 26°C, 3100 psi at 177°C, and 2010 psi at 203°C. The PPQ were resistant to normal aircraft fluids but were soluble in chlorinated solvents.
The evaluation of the surface characteristic of the PET film and fabric treated with PEG–diamine
Authors: Kim Kap Jin , Ko Sohk Won
Published: April 2003

PET film treated with PEG–diamine at 130°C was investigated for the aminolysis reaction and the pseudografted PEG content was measured with FTNMR. The hydrophilic properties of the PET film and fabric treated with PEG–diamine were estimated by their surface free energies, water‐wicking time, oily soil releasing, and static electricity. Results obtained indicated that the PEG unit was pseudografted to the PET chain end as a result of the aminolysis reaction of the ester bond of PET by the primary amine radical of PEG–diamine. The pseudografted PET content increased with the aminolysis time [PEG wt % = 2.1147 × t (h)0.4593]. γSP increased very much, γSd decreased a little, and consequently γS, ISWn, and the work of adhesion of water Wa increased with the increasing PEG content. γFW decreased very much, γFO increased a little, and consequently the difference between adhesion tensions of oily soil and water to the specimen (AFO–AFW) increased as the PEG content increased. The contact angle of oily soil to the specimen θO immersed in water increased and consequently θW and WFO/W decreased. Therefore, the PET fabric treated with PEG–diamine had very good water‐wicking, oily soil releasing, and antistatic properties.
Blends containing polymers of epichlorohydrin and ethylene oxide. II. Polyacrylates
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R.
Published: April 2003

The phase behavior of blends of various polyacrylate homopolymers and two commercial ethyl acrylate (EA) and n‐butyl acrylate (nBA) copolymers with polyepichlorohydrin (PECH), poly(ethylene oxide) (PEO), and a copolymer of epichlorohydrin and ethylene oxide [P(ECH/EO)] was examined using differential scanning calorimetry and optical indications of phase separation on heating, i.e., lower critical solution temperature (LCST) behavior. Poly(methylacrylate) (PMA) was shown to be miscible with PECH, PEO, and P(ECH/EO) while only PECH was found to be miscible with the higher polyacrylates: poly(ethyl acrylate), EA copolymer, poly(n‐propyl acrylate), and nBA copolymer. However, even PECH was found to be only partially miscible with poly(n‐butyl acrylate). In general, glass transitions observed by DSC for blends were not as broad as those found in corresponding polymethacrylate blends. All mixtures showed LCST behavior, and, based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. For PECH it appears that the interaction with polyacrylates decreases with increasing size of the alkyl group. The commercial copolymers seem to interact more exothermically with PECH than the corresponding homopolymers. The interaction with PMA is apparently larger for PECH than for PEO or for P(ECH/EO). Interactions for the latter two are about the same. The apparently exothermic interactions between ECH and EO units are not sufficiently strong to preclude miscibility of P(ECH/EO) with PMA. As for the polymethacrylates, it is clear that the chlorine moeity of PECH is needed for miscibility with higher polyacrylates.
Single phase polymer systems: CPVC/styrene copolymer alloys
Authors: Bourland Larry G. , Braunstein David M.
Published: April 2003

Random copolymers of styrene and maleic anhydride are miscible with chlorinated poly(vinyl chloride) [CPVC] in all blended proportions. Miscibility was evident in a single glass transition temperature investigated by thermal and mechanical studies. This degree of miscibility differs from the partial miscibility obtained with PVC/styrene copolymers reported previously, where single phase morphology was present only at low blend proportions. Tailoring of physical properties such as heat resistance, flamability resistance, and processability are achieved by varying the relative proportions of CPVC and styrenic copolymer in this miscible alloy system.
Adhesion quality and extent of mesophase in particulates along the whole viscoelastic spectrum
Authors: Theocaris P. S. , Ponirides P. H.
Published: April 2003

The extent of mesophase, which constitutes the boundary layer between the filler and the matrix of a composite, was defined in this paper along the whole viscoelastic spectrum of the polymeric substance constituting the matrix. The already established two‐term unfolding model1–3 was based on thermodynamic measurements of the heat capacity jumps at the glass transition regions of the filled and unfilled substances in order to define the extent of mesophase. In this paper we dispense ourselves with these delicate measurements, based on Lipatov's theory, and we use values taken from the storage and loss compliances of the composite and its constituents, along the whole viscoelastic spectrum of the composite. It was shown that the extent of the mesophase, necessary to sustain the shearing loading between phases, appearing at the glass transition zone, where the loss‐compliances presented their characteristic peaks of resonance, remained constant and almost independent of the respective values of mechanical properties at this critical region. It was shown that any set of values of the mechanical characteristic quantities, defining the composite and its constituents along the whole viscoelastic spectrum, is sufficient to evaluate the extent of the mesophase, and this boundary layer undergoes only negligible variations. Experimental evidence with typical E‐glass polystyrene and other particulates, at various volume fractions of the filler, yielded a satisfactory coincidence with the results derived by using Lipatov's theory and a constancy of the mesophase thickness along the whole temperature range.