bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of a microcomputer with a gel permeation chromatograph
Authors: Narasimhan Venkataraman , Telfer Angus R. , Huang Robert Y.‐M. , Burns Charles M.
Published: April 2003

A description is given of the interfacing of an Apple II Plus “home” microcomputer to a Waters Model 200 Gel Permeation Chromatograph fitted with ultraviolet absorbance and differential refractive index detectors. Hardware design and the software required for data collection and data reduction are described. Flow charts are provided for the various data collection, analysis, and display programs used. Emphasis is placed on the flexibility that such a system offers to the computer programmer and the experimentalist.
The impact fracture toughness of plasticized cellulose acetate and the relationship with the secondary loss transition
Authors: Fong Clifford W.
Published: April 2003

The impact fracture toughness of plasticized cellulose acetate has been determined by linear elastic fracture mechanics over the temperature range 20–70°C. A major peak in fracture toughness at −10°C has been found to correspond to a secondary loss transition in the dynamic mechanical loss spectrum of plasticized cellulose acetate. At −10°C, the fracture toughness is directly proportional to the log of the maximum strain rate.
Catalysis of the reaction between isocyanates and protonic substrates. II. Kinetic study of the polyurea foaming process catalyzed by a series of amino compounds
Authors: Borsus J. M. , Merckaert P. , Jérôme R. , Teyssié Ph.
Published: April 2003

The catalytic activity of secondary and tertiary amines were determined in the reaction of phenyl isocyanate with water and aniline, respectively, in dioxane at 25°C. The polyurea formation is largely controlled by a base‐type catalysis. However, this general behavior can be perturbed by steric factors, and still more obvious deviations appear with protic catalysts reacting rapidly with the isocyanate. The resulting urea or urethane groups can display a significant activity in relation to the nature and the composition of the reaction medium. Very good quality foams can be obtained with these protic catalysts.
Viscoelastic properties of (cellulose oligo‐oxymethylene ether) acylates
Authors: Morooka Toshiro , Norimoto Misato , Yamada Tadashi , Shiraishi Nobuo
Published: April 2003

Four kinds of (cellulose oligo‐oxymethylene ether) acylates from the acetate to the valerate were prepared by homogeneous reactions using a DMSO/PF cellulose solvent as the reaction medium. The temperature variations of dynamic modulus, loss modulus, and loss tangent for these polymers were measured. Three types of relaxation process were observed for all (cellulose oligo‐oxymethylene ether) acylates, and an additional relaxation process was detected for (cellulose oligo‐oxymethylene ether) butyrate and valerate. These processes were labelled α, β, γ, and δ in order of decreasing temperature at which they occurred. These α to δ processes were respectively attributed to: micro‐Brownian motion (α), motion of side chains (β), local mode motion involving oxymethylene groups (γ), and motion initiated by three or more methylene groups (δ).
Graft copolymerization of glass fiber and its application
Authors: Hashimoto Koshiro , Fujisawa Takao , Kobayashi Masahiro , Yosomiya Ryutoku
Published: April 2003

Modified glass fibers, containing unsaturated hydrocarbon surface groups, were prepared by a hydrothermal treatment, with allylglycidylether in excess as reagent. Graft polymerization of the treated glass fiber with styrene and methylmethacrylate was carried out in sealed tubes, under nitrogen, using benzoyl peroxide (BPO) and cumene hydroperoxide (CHPO) as initiators. When BPO was used as the initiator, the grafting efficiency was extremely low, but the graft copolymerization behavior was similar to that of usual organic polymers. With CHPO, both grafting ratio and grafting efficiency were very high. Various properties of composite materials containing grafted glass cloth were studied. Flexural strength, flexural modulus, and interlaminar shear strength increased proportionally to the increase of the grafting ratio; the same values were decreased only in a small extent after the boiling test.
Preliminary experiment of surface hardening of polymers by glow discharge polymerization
Authors: Chen K. S. , Inagaki N. , Katsuura K.
Published: April 2003

Polymers including polyethylene, polycarbonate, and polytetrafluoroethylene were modified by glow discharge polymerization to enhance surface hardness. The surface hardness of the polymer substrates could be improved by glow discharge polymerizations of silicon‐containing compounds. The mixture of tetramethylsilane (TMS) and oxygen was more effective than tetramethoxysilane to improve the surface hardness. The surface hardness improved by the glow discharge polymerization strongly depended on the nature of the polymer substrates to be modified. The adhesion between polymer films prepared from the TMS/O2 mixture by glow discharge polymerization and the polymer substrates was good.
A heat and mass transfer study—analysis of continuous processes for the coloration of polyester fabric. I. Heat transmission to the fabric system—fabric, fiber, and dye particles
Authors: Akaoui Sami E.
Published: April 2003

The three continuous processes (thermosol, high temperature steaming, and heat transfer printing) for the coloration of polyester and the involved equipment are briefly reviewed. A simple model for the transient heating of a body is developed, the model [eq.(22)] comprises a specific area of transfer parameter (As): area through which transport (of heat) takes place per unit mass of the body. This model is used in order to estimate the relative heating rates for the different geometrical approximations present in the fabric system: plate (fabric), cylinder (fiber), and sphere (dye particle). Results obtained from the more exact numerical analysis solution are used for investigating the limitations of the simple heat transfer model.
Dyeing process in a finite dyebath
Authors: Kumazawa Hidehiro , Sada Eizo , Ando Tetsuo
Published: April 2003

The processes of adsorptive and reactive dyeings of polymer film in a finite bath were formulated on the basis of pore model concept. The influence of the bath ratio on the fractional uptake or fixation was numerically analyzed. The time of half‐dyeing is proportional to the bath ratio to the power of about 0.9 within the present computational conditions. This fact is in contrast to the finding that, in an infinite bath with the same dye concentration as the initial value in a finite bath, the time of half‐dyeing is inversely proportional to the dye concentration. The relation of the total uptake or fixation to the dimensionless dyeing time θ multiplied by γ0.9 is independent of the bath ratio within an error of 5% or 8%.
Graft polymers with macromonomers. I. Synthesis from methacrylate‐terminated polystyrene
Authors: Schulz G. O. , Milkovich R.
Published: April 2003

Pure graft polymers having uniform molecular weight polystyrene side chains were prepared by free radical copolymerization of methacrylate‐terminated polystyrene macromonomers (MA‐CROMER) with ethyl acrylate, butyl acrylate, or other suitable monomers. The MACROMER monomer was synthesized by living anionic polymerization under conditions that led to very narrow molecular weight distributions. Very effective end capping produced a material that was highly monofunctional. The graft copolymers were prepared by several techniques such as free radical solution polymerization, by aqueous suspension polymerization which produced beads, or by emulsion reactions which yielded stable latices. Polymerizations were reproducible. High conversion of the MACROMER monomer into pure graft polymers was achieved, and the product was contaminated with only a little homopolymer. The milled and molded phase‐separated graft polymers had optical clarity and physical properties characteristic of polystyrene‐reinforced triblock polymers. Compositions of 20‐30% polystyrene were thermoplastic elastomers with good recovery. When polystyrene contents were increased, the graft products were strong, flexible thermoplastics with well defined yield strengths and increased permanent set. Copolymers of polystyrene macromers with acrylonitrile or vinyl chloride produced transparent polystyrene homopolymer‐free graft polymer products having improved processing over polyacrylonitrile or poly(vinyl chloride) homopolymers.
Kinetics of polymerization of styrene. The catalyst system Cu2Cl2 + AlEt3 in n‐hexane
Authors: Pandya M. V. , Deshpande D. D. , Desai N. M.
Published: April 2003

Studies on polymerization of styrene by the heterogeneous catalyst system Cu2Cl2 + AlEt3 are reported. Kinetic studies carried out at an optimum catalyst composition [Al]/[Cu] = 0.8 and aging time of 4 h give a value of 55 kJ/mol for the activation energy. The rate law can be presented as R = K [cat] [mon]2. A radical mechanism is proposed on the basis of the effect of hydroquinone and ESR spectra. The mechanism of polymerization with this catalyst system is different than that of CuCl2 + AlEt2X (X = Br, Cl), which was reported earlier.
Effect of organic peroxides on initial coloring of poly(vinyl chloride)
Authors: Hagii Hidehiko , Arai Takeshi , Yamamoto Takashi
Published: April 2003

Suspension polymerization of vinyl chloride was studied using five organic peroxides which show similar polyerization rates. Initial coloring of polymers obtained depended on the kinds of peroxides and the amount of peroxides used. Initial coloring of PVC had no relation to water solubility of the peroxides, but depended greatly on their susceptibility to hydroysis. Organic peroxides with susceptibility to hydrolysis remained low in the polymer, and yielded PVC showing preferable initial coloring.
Functionalized allyl resins. I. Photosensitivity of partially cinnamoylated allyl resins
Authors: Matsumoto Akira , Fukazawa Akeru , Oiwa Masayoshi
Published: April 2003

The preparation of photosensitive allyl resins is described. The introduction of cinnamoyl groups into allyl resins is attempted for imparting successfully photosensitive functionality. Thus, the photosensitivity of cinnamoylated poly(allyl benzoate) was first examined in detail as a model photoreaction of cinnamoylated allyl resins. Cinnamoylated poly(diallyl phthalate) was then UV‐irradiated to yield crosslinked resin, and its photosensitivity was compared with that of other allyl resins. The highest photosensitivity was observed for cinnamoylated poly(diallyl phthalate), although the mobility of the main polymer chain was considered to be lowest; this may be ascribed to the function of phthaloyl groups as photosensitizers.
Amphiphilic graft copolymer latex membranes. VI. Poly(vinyl alcohol)–acrylonitrile–N‐hydroxyethyl acrylamide graft copolymer latex membranes
Authors: Hirabayashi Yoshiaki , Satoh Hiroyuki , Ogawa Hiroshi , Ohtsuka Yasuji
Published: April 2003

Poly(vinyl alcohol)(PVA)–acrylonitrile(AN)–N‐hydroxyethyl acrylamide (HEAAm) graft copolymer latex membranes were prepared and properties of the membranes were compared with those of PVA–AN graft latex membranes and Cuprophane PT‐150. The physical constants of HEAAm were determined and the tautomerization between hydroxyethyl amide group and aminoethyl ester group upon pH changes was ascertained by infrared spectrum of poly(HEAAm) film. An increase in HEAAm content in the membrane enhanced permeabilities of solute in aqueous solutions in comparison with PVA–AN graft latex membranes, maintaining good mechanical properties in wet state. With pH variation, the permeability of the nonionic solute was unchanged, but that of the anionic solute in acidic condition was superior to that in basic condition, and the permeability of the cationic solute exhibited the opposite trend. The behavior of ionic solute were attributable to the effect of the tautomerization of the functional group in the membrane.
Modified chlorinated polypropylene as a polymer fire retardant additive in polyhydrocarbons
Authors: Koutinas A. A. , Kalfoglou N. K.
Published: April 2003

Partly modified chlorinated polypropylene (CPP) with dimethyl phosphonate side groups was prepared by reacting trimethyl phosphites and CPP at 115°C (Arbuzov type reaction). Products having different phosphorus and chlorine content were obtained, and the reduction of number‐average molecular weight M̄n with the extent of the degree of substitution was studied. The dimethyl phosphonate groups incorporated were studied by IR spectroscopy (POC at 9.6 μ and P → O at 8 μ). All products had a yellow color that may be attributed to double bond formation caused by a side dehydrochlorination reaction. Some differences of thermal stability were observed from the DSC and TGA thermograms, and no significant Tg value changes between phosphorylated products and CPP were indicated in the thermomechanical spectra. The flame retardancy of the phosphorylated products and the blends obtained by the addition of partly phosphorylated CPP to polyhydrocarbons such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) was studied using the oxygen index test. The flame retardancy of these blends was compared with the flammability of the same polyhydrocarbons containing CPP. From this comparison it is concluded that the partly phosphorylated CPP is more effective as a flame retardant additive for PE, PP, and PS than itself.
Polymerization of glycidyl methacrylate with poly(ethylene terephthalate) fibers using Fe+2–H2O2 redox system
Authors: Hebeish A. , Shalaby S. , Waly A. , Bayazeed A.
Published: April 2003

Fe+2–H2O2 redox system initiated polymerization reactions of glycidyl methacrylate (GMA) from aqueous solution with poly(ethylene terephthalate) fibers (PET) were investigated. The polymer add‐on is greatly influenced by H2O2 concentration, GMA concentration, as well as reaction time and temperature. Polymer add‐on was directly related to H2O2 concentration up to 30 meq/L and GMA concentration up to 4%. Further increase in concentrations of H2O2 and GMA resulted in lower polymer add‐on. Raising the reaction temperature from 65°C to 95°C caused a significant enhancement in the rate of polymerization, the latter follows the order 95 > 85 > 75 > 65°C. However, at 65°C, the polymerization reaction showed an induction period of about 120 min, in contrast with reactions at 75°C, 85°C, and 95°C, where no induction period was observed though the polymer add‐on was quite low at 75°C during the initial stages of the reaction. Using dimethylformamide (DMF) alone or mixed with water as polymerization medium offset the polymerization reaction. Incorporation of thioureadioxide in the polymerization system decreased the polymer add‐on significantly.
Behavior of chemically modified cottons towards thermal treatment. II. Cyanoethylated cotton
Authors: El‐Rafie M. H. , Khalil E. M. , Abdel‐Hafiz S. A. , Hebeish A.
Published: April 2003

Mill‐scoured and bleached cotton fabric, alkali‐treated cotton, and cyanoethylated cottons having 0.1%, 0.47%, 0.89%, and 1.25% nitrogen were subjected to thermal treatments. The latter were carried out at different temperatures for different durations of time. Chemical degradation of the substrates brought about by thermal treatments was assessed by copper number, carboxylic groups, nitrogen content, and degree of polymerization whereas deterioration was measured by tensile strength and elongation at break. It was found that: (a) alkali‐treated cotton undergoes higher degradation than cyanoethylated cottons; (b) cyanoethylated cottons are more susceptible to degradation than the original (mill‐scoured and bleached) cotton; (c) the magnitude of deterioration of the substrate is determined by the previous chemical treatments; and (d) with cyanoethylated cotton, the higher the cyanoethyl content (expressed as % nitrogen) the greater the DP and tensile strength.
Studies on suspension and emulsion. LX. Composite polymer emulsion film with temperature‐sensitive properties
Authors: Okubo Masayoshi , Seike Masahiro , Matsumoto Tsunetaka
Published: April 2003

The mechanical and optical properties of film cast from poly(ethyl acrylate)/polystyrene composite emulsion prepared by seeded emulsion polymerization were changed drastically by heat treatment. Such temperature‐sensitive properties can be controlled by regulating the contents and the glass transition temperature of polymer. It was concluded that such a specific phenomenon is due to phase inversion in the heterogeneous structure of the film derived from the particle morphology determined by the polymerization recipe.
Stabilization of gamma‐irradiated poly(vinyl chloride) by epoxy compounds. I. Radiation yield of hydrogen chloride and changes of epoxy group concentration in gamma‐irradiated PVC–stabilizer mixtures
Authors: Lerke G. , Lerke I. , Szymański W.
Published: April 2003

The GHCl values of γ‐irradiated PVC mixtures and the changes of the epoxy group concentration were studied after addition of various amounts of five epoxy stabilizers: diglycidyl ether of 2, 2‐bis(4‐hydroxy‐3‐methyl phenyl)propane (I), diglycidyl ether of 2, 2‐bis(4‐hydroxy‐3‐nitrophenyl)‐propane (II), styrene oxide (1, 2‐epoxy ethyl benzene) (IV), epoxidized ricinus oil (VI), and epoxidized soybean oil (Drapex 6.8.) (VII). It is stated that only about 50% of epoxy groups, declining in the system, take part in binding of HCl; the rest of these groups disappear as a consequence of other reactions. In connection with the data of the previous paper,1 the results presented indicate that the process of stabilization goes in two stages. In the first stage the process consists of the HCl capture by the epoxy groups; in the second stage, due to the remaining part of the stabilizer molecule, a protective effect occurs. This effect consists, for the stabilizers I, II, IV, of gaining the energy by the benzene ring and, for the stabilizers VI, VII, of a mechanical drawing of polymer chains, which makes the energy transfer more difficult. Having the greatest content of epoxy oxygen (about 10%), the styrene oxide (IV) stabilizes best.
Polymerization of acrylamide using the hydrogen peroxide–hydroxylamine couple
Authors: Kay Theresa A. , Rodriguez Ferdinand
Published: April 2003

The large heat of polymerization for acrylamide makes the measurement of conversion by temperature rise in an adiabatic system quite convenient. The initial monomer concentration in the reaction medium ranged from 0.2 to 0.8 mol/kg while the concentration of the two initiator components was varied from 1 to 100 mmol/kg. The adiabatic reactor was an aluminum beaker with a thin internal organic liner. The reactor was insulated and shielded. Approximate reactor charge was 200g. Iron has a pronounced accelerating effect on the rate. The predominant reaction appears to be the iron‐catalyzed decomposition of hydrogen peroxide in the presence of small amounts of hydroxylamine hydrochloride. At hydroxylamine to peroxide ratios greater than about 1:2, there seems to be no further benefit from hydroxylamine additions. The activation energy is lowered by the addition of iron decreasing from 18.7 kcal/mol with no added iron to 4.5 kcal/mol when the system contains 1 ppm iron.
Effect of clay on vulcanization, network structure, and technical properties of natural rubber in the presence of silane coupling agents
Authors: Pal Pranab K. , Chakravarty S. N. , De S. K.
Published: April 2003

The presence of silane coupling agents do not cause a change in network structure in clay‐filled natural rubber vulcanizates, both in sulfur vulcanization and peroxide vulcanization systems. However, the improvement in technical properties in the presence of silane coupling agents is more in the peroxide vulcanization system and is accompanied by enhanced polymer—filler interactions. Scanning electron microscopy (SEM) studies have been made in order to understand the failure behavior.
Antioxidant effects during blade abrasion of natural rubber
Authors: Pulford C. T. R.
Published: April 2003

A blade abrasion device similar to that developed by Champ, Southern, and Thomas has been used to determine the wear rates of everal simple carbon black‐filled natural rubber materials over a range of frictional loading at room temperature in air. The materials show two mechanisms of wear depending on the amount of frictional load applied. Smearing, the mechanochemical decomposition of the wearing surface leading to a tarlike wear product, occurs at low frictional loads and is replaced by particulate debris created by cohesive rupture at higher frictional loading. It was found that a representative alkyl/aryl paraphenylenediamine and hindered phenol antioxidant were only effective in reducing the rate of wear during smearing, when degradation processes are important. Furthermore, the reduction in wear rate during smearing was quite similar for these two antioxidants.
Rheology of unsaturated polyester resins. I. Effects of filler and low‐profile additive on the rheological behavior of unsaturated polyester resin
Authors: Han Chang Dae , Lem Kwok‐Wai
Published: April 2003

Measurements were taken of the bulk rheological properties of concentrated suspensions of particulates in unsaturated polyester resins, using a cone‐and‐plate rheometer. The particulates used were clay, calcium carbonate, and milled glass fiber. With clay and milled glass fibers, shear‐thinning behavior of suspensions was observed at low shear rates or low shear stresses as the concentration of particulates was increased, whereas concentrated suspensions of calcium carbonate exhibited Newtonian behavior over the range of shear stresses or shear rates investigated. The cone‐and‐plate rheometer was also used for measurements of the bulk rheological properties of various mixtures of polyester resin and low‐profile additives. For low‐profile additives, solutions, in styrene, of poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) were used. It was found that the bulk viscosities of all mixtures of polyester resin and PVAc solution lie between those of the individual components, whereas the bulk viscosities of some mixtures of polyester resin and PMMA solution go through a minimum and a maximum, depending on the composition of the mixture. While all mixtures of polyester resin and PVAc solution exhibited negligible normal stress, some mixtures of polyester resin and PMMA solution exhibited noticeable normal stresses. It should be mentioned that polyester resin follows Newtonian behavior. It turned out that all mixtures of polyester resin and PVAc solution exhibited clear, homogeneous solutions, whereas mixtures of polyester resin and PMMA solution exhibited optical heterogeneity, i.e., turbidity. When polyethylene powders were used as low‐profile additives, suspensions of polyester resin and polyethylene powders exhibited negative values of normal stress as the concentrations of suspension reached a critical value. When both filler and low‐profile additive were put together in polyester resin, the rheological behavior became quite complex, indicating that some interactions exist between the filler and the low‐profile additive.
New epoxy resins. III. Application of fourier transform IR to degradation and interaction studies of epoxy resins and their copolymers
Authors: Chen C. S. , Bulkin B. J. , Pearce E. M.
Published: April 2003

In the Fourier transform infrared (FT–IR) study, diglycidyl ether of bisphenol A (DGEBA) did not show aldehyde or perester absorption when it was normally cured with trimethoxyboroxine (TMB) under a nitrogen atmosphere. Neither alumina nor gold surfaces would cause oxidation of the system. In air, alumina appeared to accelerate the oxidation when compared to gold. The cure of the epoxy in oxygen appeared to cause increased Claisen rearrangement when compared with the same cure in a nitrogen atmosphere. The DGEBA cured with TMB under air or nitrogen atmospheres showed differences in their degradation patterns. The TMB‐cured DGEBA and diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) copolymer had a higher degree of reaction and lower degradation than was shown by the synthetically generated spectra based on the FT–IR summation of the spectra of the respective homopolymers.
The interaction of a cationic silane coupling agent with mica
Authors: Favis B. D. , Blanchard L. P. , Leonard J. , Prud'Homme R. E.
Published: April 2003

Carbon analysis was used as a method for measuring the quantity of a cationic vinyl benzyl silane (CVBS) adsorbed onto the surface of mica. The results obtained indicate that CVBS can be applied from aqueous solution over a wide pH range with best treatment in neutral and acidic media. The amount adsorbed depends on the concentration of the treating solution in the lower concentration range while in the higher range, the adsorption is less dependent on concentration. The relationship, silane adsorption vs. time of treatment, shows a steplike dependence. It is suggested that each step corresponds to a monolayer coverage. The data indicate that CVBS on mica is a highly ordered and closely packed multilayer phase with the silane molecules oriented normal to the surface. The multilayer adsorption of silane onto silane in this system may be compared in some respects to polymer crystal growth.
The surface orientation of polystyrene measured by liquid contact angle
Authors: Wang Li‐Hui , Porter Roger S.
Published: April 2003

The surface contact angle of glycerol and of water on polystyrene (PS) films has been found to depend on the extent of uniaxial draw for atactic PS. The contact angle depends on direction for the smooth films of PS drawn by solid state coextrusion. Results as a function of draw ratio to values over 4 on these noncrystalline PS samples, Mw = 6 × 105, have also been interrelated with other measures of orientation such as the anisotropy of surface and bulk properties measured, respectively, by dichroic reflectance infrared spectroscopy and by birefringence.
Main functions of iron compounds as smoke suppressant in poly(vinyl chloride) combustion
Authors: Michel A. , Bert M. , Van Hoang Tran , Bussiere P. , Guyot A.
Published: April 2003

Whatever the state of the iron compounds as smoke suppressant during the combustion of poly(vinyl chloride), they lead rapidly to native αFe2O3 in the char residue left after dehydrochlorination. It causes incandescence of the char residue and catalyzes its oxidation into carbon monoxide and carbon dioxide that contributes to decreasing the amount of available carbon for the soot formation after self‐ignition. FeCl2 and FeCl3 are the precursors of αFe2O3, which is the true compound as smoke suppressant. Nevertheless, as intermediate, iron chlorides are able to modify the degradation processes, and they favor the formation of light tars instead of heavy tars. For that reason the iron compounds cause the formation of smoke at lower temperature than for pure PVC, but, as αFe2O3 is formed, the smoke production levels off and then decreases. The higher the ease of the iron compounds to give chlorides through reaction with HCI and further native αFe2O3, the higher the ease of the additive to cause the oxidation of the char residue sooner and in consequence to decrease the smoke level. In the PVC combustion three main steps may be distinguised: dehydrochlorination step between 200–300°C; tars aerosols formation from the char residue between 300°C and self‐ignition; at temperature higher than self‐ignition, formation of soot from the previous tars as precursors.
Simulation of nylon 6 polymerization in tubular reactors with recycle
Authors: Gupta Santosh K. , Kunzru D. , Kumar Anil , Agarwal K. K.
Published: April 2003

In the hydrolytic polymerization of ϵ‐caprolactam, the ring opening of the monomer is much slower than the polyaddition reaction. Hence, the mixing of aminocaproic acid to the feed results in a faster conversion of the monomer. Industrially, this fact is exploited by using a recycle stream. An isothermal plug flow reactor (PFR) with a recycle is simulated in this study, using two techniques: the method of successive substitutions and Wegstein's method. It is found that, under certain operating conditions, the use of a recycle stream gives higher monomer conversions and lower cyclic dimer concentrations than either a PFR or a homogeneous continuous‐flow stirred‐tank reactor (HCSTR), with the degree of polymerization almost the same as that obtained in an HCSTR, and thus offers a considerable advantage. However, when a recycle reactor is coupled with a subsequent flashing operation and a finishing reactor, these advantages are considerably reduced.
Poly(methyl methacrylate) as incorporation medium for spent ion‐exchange resin. II. Simulated resin
Authors: Ghattas N. K. , Ikladious N. E. , Eskander S. B.
Published: April 2003

The incorporation and final containment of spent ion‐exchange resins into poly(methyl methacrylate) (PMMA) was investigated in the present study. Test blocks of PMMA with 50% incorporated inactive resin were subjected to radiation doses of 105–107 rad at a dose rate of 50 rad/s. The high radiation doses impaired the mechanical properties of the final products. Both compressive strength and hardness decreased with increasing the particle size of the ion‐exchange resin. DTA diagrams showed the thermal instability of the final solidification product at about 400°C. Leaching experiments on incorporated blocks of active resins labelled with Cs‐137 and Ce‐144 showed that cesium activity was more easily released in leachant solutions than was cerium activity. Cumulative leaching rates for both Cs and Ce were lower in deionized water than in undergroud water. The mechanical, thermal, and leaching data obtained illustrate the suitability of PMMA for immobilization of spent ion‐exchange resins with low specific activity.
Melt flow crystallization of ultrahigh molecular weight polyethylene under curvilinear flow conditions
Authors: Zachariades Anagnostis E. , Logan J. A.
Published: April 2003

Multiaxially oriented ultrahigh molecular weight polyethylene films were prepared recently under curvilinear flow conditions generated by the combined effects of compression and rotation. The films were prepared by melt flow crystallization in an optical apparatus specially designed for rheo‐optical observations. Morphological studies indicate that the films were fibrillar with the fibrils oriented along the circular flow lines. The fibrils were lamellar, and their lamellar thickness (150–450 Å) and spacing (400–2000 Å) depended on the processing conditions. The film exhibited strong birefringence (1.4 × 10−2) and had a Young modulus of 15–25 GPa along the flow lines and 3–5 GPa in the transverse direction.
Pervaporation of methanol–water mixture by poly(γ‐methyl L‐glutamate) membrane and synergetic effect of their mixture on diffusion rate
Authors: Suzuki Fumio , Onozato Kenji
Published: April 2003

The pervaporation behaviors of methanol–water by poly(γ‐methyl L‐glutamate) (PMLG) membrane at non‐steady‐ and steady‐state permeation were investigated. The values of t1/2 (time required to reach a half value of steady‐state permeation flux) for methanol and water changed and did not change with the component in feed, respectively. Both of the average diffusion coefficients for methanol–and water–PMLG from the mixture changed exponentially with the sorption amount of methanol by the synergetic effect on diffusion. The difference in behavior of non‐steady and steady state diffusion was explained by whether Do (diffusion coefficient at zero penetrant concentration) was influenced by the concentration distribution of penetrant in PMLG membrane.
Identification of some boron‐based curing agents in cured epoxy systems by computer‐assisted infrared spectroscopy
Authors: Davidson R. G. , Mathys G. I.
Published: April 2003

The use of computer‐assisted infrared spectroscopy has allowed identification of three different boroxines and a boron trifluoride complex used as curing agents in cured epoxy resins. Boroxines were distinguished from a boron trifluoride complex by the BO stretch absorption near 1400 cm−1 in the solid state. Detection of this absorption was enhanced by spectral subtraction methods in which the reference spectrum was that of the parent resin, or a suitably cured system of similar structure. Distinction between different boroxines was achieved by analysis of the gases evolved from samples heated at 300°C in nitrogen. Identification of the alcohol fraction of the original boroxine was improved by subtraction of the spectrum of water vapor. Boron trifluoride was detected in the gases evolved at 450–500°C from BF3‐cured systems, and also in the liquid pyrolyzates. Further simplification of the 300°C gas spectra by subtraction of alcohol and carbon dioxide revealed the presence of acrolein in the gases from boroxine‐cured systems while BF3‐cured systems yielded acetaldehyde. These differences may be associated with different end groups in the cured resins.
NO2‐initiated polymerization of acrylonitrile
Authors: Mishra Mahendra Kumar , Bhadani Suraj N.
Published: April 2003

The polymerization of acrylonitrile initiated with NO2 in dimethyl sulfoxide has been studied. The kinetics of polymerization was followed gravimetrically. The effect of monomer, initiator, and temperature on the rate of polymerization has been given. The overall activation energy was found to be 18.06 kcal.mol−1. The polymerization with NO2 appears to be initiated by a free‐radical mechanism.
Radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. II. Dependence on radiation dose and blend composition
Authors: Bowmer T. N. , Hellman M. Y. , Vroom W. I.
Published: April 2003

The radiation crosslinking of poly(vinyl chloride) (PVC) blended with trimethylolpropanetrimethacrylate (TMPTMA) has been examined. The polyfunctional TMPTMA undergoes polymerization incorporating the PVC into a 3‐dimensional network. The kinetics and mechanisms of these crosslinking reactions were studied with particular reference to dependence on radiation dose and blend composition. The crosslinking rate was found to be proportional to the TMPTMA concentration. As the TMPTMA concentration decreased, soluble graft copolymers were produced in addition to insoluble networks. A gel permeation chromatography technique provided compositional information on the gel and sol fractions. The competition between polymerization, grafting, and degradation reactions was examined.
High performance epoxy resins cured in the presence of BF3 catalyst
Authors: Munns Thomas E. , Seferis James C.
Published: April 2003

Dynamic mechanical experiments have been conducted on an epoxy system made with tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM) and polyglycidyl ether of Bisphenol A Novalac that were cured with 4,4′‐diaminodiphenyl sulfone (DDS) in the presence of Boron trifluoride monoethylamine catalyst (BF3:EtNH2). As the concentration of BF3:EtNH2 increased, the low temperature β‐transition magnitude increased slightly. The α1‐transition observed in the uncatalyzed system decreased significantly with the addition of BF3:EtNH2 catalyst. The α2 or glass transition temperature of this system increased with increasing catalyst concentration. Both the catalyzed and uncatalyzed epoxy formulations studied in this work are important due to their similarity to systems used commercially in epoxy matrix composites.
Processing–mechanical property relationships in injection moldings of polybutylene
Authors: Guo M. , Bowman J.
Published: April 2003

Two unfilled nonpigmented extrusion grades of polybutylene have been injection‐molded into a tensile bar mold under a wide range of barrel and mold temperatures. The overall structure of the moldings has been determined and correlated with processing conditions. The short term tensile mechanical properties of the moldings have been ascertained and correlated with molding structure. For low mold temperatures, the Young's modulus and tensile strength of injection moldings of polybutylene are controlled by the extent of and structure within the highly oriented skin. Low barrel temperatures can give rise to highly crystalline thick skins that treble the Young's modulus and fracture stress, when compared to high barrel temperature moldings. Increasing the mold temperature introduces a brittle response in polybutylene injection moldings. Modulus is controlled, at the high mold temperatures, by the skin thickness and by the crystallinity of the material comprising the core of the molding.
Hydraulic permeability of water in poly(vinyl alcohol) membranes as a function of the degree of hydration
Authors: Kojima Y. , Furuhata K. , Miyasaka K.
Published: April 2003

Poly(vinyl alcohol) membranes were prepared by solution cast and subsequent annealing. The degree of crystallinity of the membranes at the dry state was not affected by the annealing, whereas the degree of hydration H was markedly changed. This made us assume a double network structure. Hydraulic permeability of water, Kw, in PVA membranes was measured to discuss the relation between H and the permeability. Kw increased with increasing H with increasing slope. The linear relation between the reduced permeability Kw/H and 1/H, expected from a free volume theory, was not obtained in the PVA membranes. This nonlinearity of the relation was confirmed also in various hydrogels reported by other authors. We found that a linear relation between H and logarithm of Kw/H, as expected from the Ogston's relation, is achieved in PVA and many other hydrogel membranes with H from 0.4 to 0.9. Under a given degree of hydration, the activation energy of permeation of PVA membrane was larger than that of cellulose, owing to the large amount of bound water in PVA membrane.
Silylation of water glass. IV. Synthesis and characterization of silylated silicic acids
Authors: Inoue Hiroshi , Kohama Shigemi
Published: April 2003

Trimethylsilylated (TMSS) and dimethylphenylsilylated silicic acids (DMPS) were prepared via extraction with tetrahydrofuran, started from aqueous sodium silicate. Characterization of these silylates based on the 13C and 29Si NMR spectra, X‐ray diffraction, gel permeation chromatography, and solution viscosity were conducted to study their molecular structures. It was found that the GPC elution volume was significantly deviated from the calibration curve and also the exponents in solution viscosity vs. molecular weight (M̄n) relationship were very low, almost 0.3. These solution properties suggest that such silylates have compact spherical structures with a high degree of branching, also supported from the other data.
Gel permeation chromatographic analyses of resole phenolic resins
Authors: Rudin Alfred , Fyfe C. A. , Vines S. Martin
Published: April 2003

Tetrahydrofuran solutions of resole polymers were analyzed by gel permeation chromatography (GPC) on crosslinked polystyrene gel packings. The best separation was obtained with low solvent flow rates in low porosity columns. Irregular elution volumes were observed, but the effects of this erratic behavior can be eliminated by referencing retention times to that of a marker compound such as benzene or phenol. A calibration and data analysis method are presented which utilizes hydrodynamic volumes. Phenolic polymers vary in shape and ability to form hydrogen bonds with solvent; hence their molecular weights cannot be estimated from GPC data. Separation of the constituent species of resole samples is shown to be incomplete, because of aggregation between the various phenol derivatives. Particular peaks in the GPC chromatogram could generally not be assigned to individual species. Despite these limitations, GPC is a useful tool for charcterizing phenolics, and several applications are reviewed here.
Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes
Authors: Hayashi Sadao , Hirai Toshihiro , Hayashii Fumihiko , Hojo Nobumasa
Published: April 2003

Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n‐hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm2. The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n‐haxane or a poor solvent for PVAc.
Infrared spectroscopy and conformation of alkyl vinyl ketone monomer
Authors: Kinoshita Akihiro , Naito Ikuo , Namariyama Yoichi
Published: April 2003

The correlation between IR spectra and conformations was examined in alkyl vinyl ketone monomer. The stretching absorption bands of double bonds shift to lower wave number with the decrease in Taft's σ* values of alkyl groups, and, conversely, the deformation band of the vinyl group shifts to the higher wave number. The inductive effect of the alkyl group is aparently three times larger in s‐cis conformation than that in the s‐trans. Absorption coefficients in the double‐bond stretchings (A CO and A CC) were measured in each conformation. Both conformations have a nearly equal value of A CO. The ratio (A s‐cis/A s‐trans) CC is 3.4 ±1.0. The ratios (A′ CO/A′ CC) are 4.5 ±0.6 for the s‐cis conformation and 15±2 for the s‐trans conformation in all alkyl vinyl ketones studied.
Application of multimethod procedure for characterization of branched polydisperse polymers
Authors: Dobkowski Zbigniew
Published: April 2003

The multimethod procedure for characterization of branched polydisperse polymers, including gel permeation chromatography, solution viscometry, melt viscometry, and differential scanning calorimetry, is described. An equation relating the average branching degree g¯x and the average number of branch points n̄bx has been derived and compared with the theoretical Zimm–Stockmayer equation. It has been found that both equations can be consistent for theta solvent and for the branching degree exponent b=1.5. Experimental data are given for trifunctionally branched bisphenol A polycarbonate.
Thermal stability of grafted fibers
Authors: Sundardi F. , Kadariah  , Marlianti Isni
Published: April 2003

This paper presents the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene‐, polyester‐, and rayon‐grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1‐vinyl 2‐pyrrolidone, acrylic acid, N‐methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT‐30. It was found that the thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not much improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of CO and CC bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1‐vinyl 2‐pyrrolidone monomer, which may be due to the lower thermal stability of poly(1‐vinyl–2‐pyrrolidone), compared to the polypropylene or polyester fibers.
Photooxidation of polystyrene: Irradiation at 254 and 365 nm
Authors: Otocka E. P. , Curran S. , Porter Roger S.
Published: April 2003

Studies have been made of the near surface photooxidation of atactic polystyrene films prepared in the absence of air. The samples were photooxidized on exposure to air at two frequencies, 254 and 365 nm, using a calibrated mercury irradiation source with filters. Most studies were made at 40°C and as a function of irradition time with the reactions characterized by changes in molecular weight and composition. The former was evaluated by gel permeation chromatography and the latter by transmission Fourier transform infrared spectroscopy and by multiple‐internal‐reflectance infrared spectra using different angles and different crystals to evaluate compositions as a function of film depth. Species identified in photooxidation include the generation of hydroperoxides and the appearance of carbonyl bands with the latter identified by the spectral shift asociated with the exposure of the photooxidized polystyrene surface to ammonia. These results suggest that principal products of near‐surface oxidation of polystyrene are carboxylic acids.
Toughened polystyrene containing high cis‐1,4‐polybutadiene rubber
Authors: Sardelis K. , Michels H. J. , Allen G.
Published: April 2003

High cis ‐1,4 ‐polybutadiene has been used to prepare toughened polystyrene in an attempt to improve its low temperature impact properties. A range of physical and mechanical properties was obtained by keeping the amount of rubber and the polymerization conditions constant, and varying the rate of agitation in a purpose ‐built reactor system. Although a good balance of tensile and impact properties is obtained at room temperature, the rubber partially crystallizes when the polyblends are cooled to below −40°C. This should decrease the efficiency of rubber particles to create and terminate crazes. However, it is significant that the developed crystallinity decreases with the rubber phase volume, and is suppressed almost completely at about 21% rubber phase volume (RPV). The factors influencing the RPV are discussed, and a study of the phase inversion with three different types of rubber shows that its duration depends on the viscosity of the styrene/rubber system.
Physical aging in particulate‐filled composites with an amorphous glassy matrix
Authors: Yilmazer Ulku , Farris Richard J.
Published: April 2003

Physical aging was studied on particulate ‐filled glassy network polymers by means of mechanical ‐dilatational, differential scanning calorimetry (DSC) and density measurements on specimens that were aged at room temperature. The composites aged for 0.5 day fractured in a brittle manner at a constant ultimate stress, which is close to the tensile strength of the unfilled material, regardless of the filler content and the presence of a coupling agent. This type of mechanical behavior is caused by the compressive residual stresses that are present due to curing and differential thermal shrinkage. As aging takes place, the compressive residual stresses are relieved; as a result the ultimate tensile strengths of the composites decrease. The 120 ‐day ‐old untreated glass bead containing composites exhibited dilatation and yield in mechanical ‐dilatational testing. This type of behavior is described as “having no adhesion” between the filler and the matrix. The 120 ‐day ‐old composites with coupling agent ‐treated glass beads fractured at a tensile stress which is equal to 1/1.6 the tensile strength of the unfilled material. These materials did not exhibit dilatation and yield in mechanical ‐dilatational testing. Density and DSC data indicate densification and enthalpy relaxation upon again and support the hypothesis presented for the observed change in the mechanical ‐dilatational behavior.