bluuebunny/crossref_metadata_2025 huggingface dataset:
Water‐soluble copolymers. VI. Dilute solution viscosity studies of random copolymers of acrylamide with sulfonated comonomers
Authors: Neidlinger Hermann H. , Chen Gow‐Sheng , McCormick Charles L.
Published: April 2003

Dilute solution viscosity of a series of random copolymers of acrylamide (AM) with sodium‐2‐acrylamido‐2‐methylpropane sulfonate (NaAMPS) and with sodium‐2‐sulfoethylmethacrylate (NaSEM) has been studied using a four‐bulb shear dilution capillary viscometer. The hydrodynamic volume of the copolymers in aqueous media was determined as a function of salt concentration, temperature, shear rate, and time. A linear relationship was observed between the intrinsic viscosity [η]0 and the reciprocal of the square root of ionic strength in sodium chloride solutions, with salt concentrations varying from 0.043M to 0.257M. Negative temperature coefficients for [η]0 indicate a decrease in the hydrodynamic volume of the ionic polymer molecules with increasing temperature. The relative zero‐shear‐intrinsic‐viscosity change in distilled water to 0.257M sodium chloride aqueous media is used to elucidate viscosity–structure relationships. A maximum value is reached for this parameter at a composition of about 30 mol % of ionic comonomers for AM–NaAMPS and AM–NaSEM copolymer series.
Reactions of diaminoalkanes with bismaleimides: Synthesis of some unusual polyimides
Authors: White Jerry E. , Scaia Mark D. , Snider Deborah A.
Published: April 2003

Michael additions of the secondary diamines N,N′‐dimethyl‐1,6‐hexanediamine (14) or piperazine to the electrophilic carbon–carbon double bonds of N,N′‐bismaleimido‐4,4′‐diphenylmethane (2) or N,N′‐bismaleimido‐1,8‐octane (4) afford four unusual, high‐molecular‐weight (ηinh = 0.49–2.16 dL/g) polyimides (10–13). The most interesting of these, polymer 12 (the product of 4 and 14), is a tough elastomeric resin with a glass transition temperature (Tg) near 0°C; in contrast, 10, 11, and 13 exhibit Tg >86°C. Freshly prepared 12 is soluble and thermoplastic (12 is readily compression molded at 110°C), but the bulk polymer crosslinks slowly under ambient laboratory conditions and eventually (48 days) becomes insoluble, while 10, 11, and 13 remain soluble indefinitely. Along with further comparisons of the properties of 10–13, details of the synthesis and characterization of these new polyimides are described. Also discussed are reactions of bismaleimide 2 with 1,6‐diaminohexane, which unlike the formation of linear 10–13, generate crosslinked, insoluble products.
Calculation of profiles of temperature and state of cure developed within the rubber mass in injection molding process
Authors: Sadr‐Bazaz A. , Granger R. , Vergnaud J. M.
Published: April 2003

Higher and higher temperatures for vulcanization and storage bulb are being used in order to reduce the time of cure cycle in processes of rubber injection molding. The purpose of this work was to show that the temperature gradients as well as the profiles of the state of cure developed in the rubber mass could be predicted by using the kinetics of reaction, the physical properties of the rubber, and a convenient model. Although vulcanization is a complex series of reactions, the overall result by considering the heat of reaction could be described by a single first‐order reaction. The calculation was solved applying an explicit method with finite differences, by taking into account the internal generation of heat due to the cure reaction and the heat transfer by conduction with a temperature dependence of the physical properties of the rubber. The effect of the values of the temperature of the mold and storage bulb on the profiles of temperature and state of cure developed within rubber was studied by considering rubber sheets of different thicknesses.
Epoxidation of natural rubber latices: Methods of preparation and properties of modified rubbers
Authors: Burfield David R. , Lim Kooi‐Ling , Law Kia‐Sang
Published: April 2003

Studies in the epoxidation of natural rubber latices are described. Investigated epoxidation routes include the use of bromohydrin intermediates, hydrogen‐peroxide‐catalyzed systems, and preformed peracetic acid. The latter reagent allows almost quantitative epoxidation of natural rubber up to high modification levels with no detectable side reactions. Kinetic studies show that the peracetic acid epoxidation is second order in peracid and rubber hydrocarbon with an overall activation energy of 56.2 kJ/mol. Epoxidation leads to a progressive increase in Tg and polymer density with increase in modification level. The effect of modification on solvent swelling and mechanical properties of the DICUP‐crosslinked rubbers are reported.
Adsorption of water‐soluble, nonionic polymers onto cellulosic fibers
Authors: Ishimaru Yutaka , Lindström Tom
Published: April 2003

The adsorption of 12 different nonionic water‐soluble polymers, methylcellulose (MC), hydroxypropylcellulose (HPC), polygalactomannan (PGM), polyglycidol (PGD), polyacrylamide (PAAm), methylolated polyacrylamide (MPAAm), polymethacrylamide (PMAAm), three differently hydrolyzed poly(vinyl acetate)s (PVAs), poly(vinyl) methyl ether (PVME), and poly(vinyl pyrrolidone) (PVP) onto bleached kraft pulp (BK), unbleached kraft pulp (UK), and a groundwood pulp (MP) has been investigated under aqueous conditions with attention to the functional groups in the polymers and the chemical character of the pulps. It was found that the adsorption was often selective toward one of the pulps. In order to gain some additional information on these interactions, some adsorption experiments were also performed on acetylated pulps. Some polymers (PGD, PAAm, MPAAm, and PVA 124) having both proton donating and accepting capability were not adsorbed onto any of the pulps. This was attributed to intramolecular hydrogen bonding in these polymers. Some polymers (PVA 224, PVME, and PVP) were strongly adsorbed onto UK but not at all onto BK. It was suggested that in these cases the adsorptive interaction was between phenolic and/or catecholic groups in the lignin on the UK and proton accepting sites on the polymers. However, for three polymers (MC, PGM, and PMAAm), a more general type of hydrogen bonding interaction was considered. For some polymers (HPC, PMAAm, and PVA 420) having hydrophobic groups, it was suggested that hydrophobic interactions were important for the adsorption.
Effects of low levels of methacrylic acid on the swelling behavior of poly(2‐hydroxyethyl methacrylate)
Authors: Pinchuk L. , Eckstein E. C. , Van De Mark M. R.
Published: April 2003

The effects of low levels of methacrylic acid (MAA) (less than 4 mol %) and a crosslinker (less than 0.3 mol %) on the equilibrium swelling and water content of poly(2‐hydroxyethyl methacrylate) (pHEMA) hydrogels were investigated. Numerous pHEMA disks, some of which were doped with small amounts of MAA, were placed in swelling baths simulating possible urological as well as physiological conditions. Several interesting facts are reported, such as, in dilute urea (0.15M) or in alkali solution, gels containing 2% MAA are capable of swelling to 3600% their size in mild acid, saline, or distilled water, with associated water contents that range as high as 98%. Also, gels containing small amounts of MAA and finite crosslinker content can be made that are soluble in mild urea or alkali solution. The significance of this study is that gels or gel surfaces can be fabricated that are highly responsive to their environment. In addition, since the level of MAA that cause this shrink–swell behavior are well within the impurity levels of MAA found in unpurified commercial HEMA, it is conceivable that this shrink–swell behavior may have occurred in early studies of implanted pHEMA gels, thus confusing the subsequent evaluation of its performance as a biomaterial.
Cation exchange resin from sulfonated poly‐N‐vinylcarbazole–formaldehyde copolymer
Authors: Biswas Mukul , Bagchi Subrata
Published: April 2003

A cross‐linked copolymer of poly‐N‐vinylcarbazole and formaldehyde has been sulfonated to yield a cation exchange resin. The resin has been characterized by elemental analysis and by evaluation of total and salt‐splitting capacities and pH‐metric titration behavior. The resin has improved capacity (ion exchange) relative to other N‐vinylcarbazole based resins and behaves as a polymeric dye.
Effect of pH of silane solution on the adhesion of polyimide to a silica substrate
Authors: Suryanarayana Darbha , Mittal K. L.
Published: April 2003

We show that the pH of the aminosilane solution has a significant effect on its efficacy as an adhesion promoter. Furthermore, the maximum adhesion is observed to be in the pH range close to the natural pH of the dilute silane solution. It would be interesting to extend this kind of study to other silanes as well as to various coating materials.
Rheological behavior of polymer blends
Authors: Chuang Hsiao‐Ken , Han Chang Dae
Published: April 2003

Steady and oscillatory shearing flow properties of compatible and incompatible polymer blend systems were measured, using a cone‐and‐plate rheometer. The compatible blend systems investigated are blends of two low‐density polyethylenes (LDPE) having different values of molecular weight and blends of poly(methyl methacrylate) (PMMA) with poly(vinylidene fluoride) (PVDF). The incompatible blend system investigated is a blend of poly(methyl methacrylate) (PMMA) with polystyrene (PS). It was found that (1) plots of first normal stress difference (τ11 – τ22) vs. shear stress (τ12) and plots of storage modulus (G′) vs. loss modulus (G″) for the LDPE blends become independent of temperature and blend composition; (2) plots of τ11 – τ22 vs. τ12, and G′ vs. G″ for the PMMA/PVDF blends become independent of temperature but dependent upon blend composition. It was found further that, for the incompatible PMMA/PS blends, the dependence of τ11 – τ22 on blend composition, when plotted against τ12, is different from the dependence of G′ on blend composition, when plotted against G″. However, in both compatible and incompatible blend systems, plots of τ11 – τ22 vs. τ12 and plots of G′ versus G″ are independent of temperature. The seemingly complicated composition‐dependent rheological behavior of the incompatible blend system is explained with the aid of photomicrographs describing the state of dispersion.
Properties of 2,3‐dicarboxy cellulose combined with various metallic ions
Authors: Maekawa Eiichi , Koshijima Tetsuo
Published: April 2003

2,3‐Dicarboxy cellulose and partially oxidized 2,3‐dicarboxy cellulose were prepared in good yields from the corresponding dialdehyde cellulose obtained by periodate oxidation of cellulose according to a modification of the method described by Hofreiter, Wolff, and Mehltretter [J. Am. Chem. Soc., 79, 6457 (1957)]. The 2,3‐dicarboxy cellulose oxidized to nearly 100% oxidation level was completely soluble in water, but the 2,3‐dicarboxy cellulose of 70% oxidation level was not. The former 2,3‐dicarboxy cellulose took up various metallic ions other than alkali metals to form a precipitate or solid. The metal contents taken up corresponded to the theoretical values calculated as combined in the form of metallic salt of the carboxylic acid group. 2,3‐Dicarboxy cellulose combined with metallic ions such as copper, cobalt, and nickel ions gave viscous, gel‐like products, which solidified when exposed to air. The properties of products combined with such metallic ions are discussed.
Mechanical and transport properties of coextruded films
Authors: Kim Y. J. , Han C. D. , Song B. K. , Kouassi E.
Published: April 2003

Two‐layer films were produced by using the blown‐film coextrusion apparatus constructed in our laboratory. For this study, we have produced films of the following combinations: (1) LDPE/CXA 3095; (2) LDPE/Plexar 3; (3) LDPE/EMA; (4) nylon 6/LDPE; (5) nylon 6/CXA 3095; (6) nylon 6/Plexar 3; (7) nylon 6/EMA. Tensile properties of the coextruded films were measured with an Instron testing machine, and correlated to processing variables, namely, takeup ratio and blowup ratio. From tensile property measurements, we have found that both the ultimate tensile strength and the tensile modulus of coextruded films follow the additivity rule with respect to the volume fraction of the individual components. With the films produced, we also conducted dynamic mechanical measurements with the aid of a Rheovibron Dynamic Viscoelastometer DDV‐II, and attempted to test the Zorowski–Murayama theory to determine the adhesion characteristics of the coextruded films. Furthermore, permeability of the coextruded films to gases (namely, N2, O2, and CO2) was measured by using a pressure differential apparatus constructed in our laboratory. We have found that the permeability of composite films follows the inverse additivity rule, i.e., the reciprocal of the permeability of composite film is given by the sum of the reciprocals of the permeabilities of the individual layers.
Study of rubber oxidation by thermoanalysis
Authors: Lye P. H. , Toh H. K.
Published: April 2003

A method using the DSC was utilized whereby the oxidation of natural rubber was studied by adapting the procedures developed by Kissinger, Doyle, and Ozawa for thermoanalysis. Thus oxidative induction time of several hours for a particular rubber sample can be estimated in a relatively short time. Some of the results of this method are compared with those from other established methods, the estimated oxidative induction time showing a good correlation with some of the systems tested. The validity and limitations of this method are discussed.
Resorbable materials of poly(L‐lactide). V. Influence of secondary structure on the mechanical properties and hydrolyzability of poly(L‐lactide) fibers produced by a dry‐spinning method
Authors: Leenslag J. W. , Gogolewski S. , Pennings A. J.
Published: April 2003

Fibers of poly(L‐lactide) (PLLA) with a loosened fibrillar structure were produced by solution spinning from a good solvent (chloroform) in the presence of various additives (camphor, polyurethanes). No decrease in mechanical properties was observed as compared with PLLA fibers spun from a good solvent only. In vitro degradation studies showed that the rate of degradation of PLLA fibers with the loosened fibrillar structure was increased approaching that found for fibers composed of the homopolymer of glycolide or copolymers of glycolide and L‐lactide. Helices on the fiber surface caused by melt fracture during spinning of the fibers leads to higher knot strengths of the hot‐drawn PLLA fiber up to 70% of the tensile strength.
Grafting of poly(methyl methacrylate) in aqueous slurries of wood pulp
Authors: De Carvalho Laura Hecker , Rudin Alfred
Published: April 2003

Methods for initiating the free radical graft polymerization of methyl methacrylate onto wood pulp were investigated. Processes considered were all carried out in water slurries of the cellulose, for simplicity and low cost. Of the methods studied only three provided high conversions of monomer to polymer and reasonably good grafting efficiencies. These are ceric ion initiation, a redox reaction with ferrous ion and hydrogen peroxide, and initiation by potassium permanganate/nitric acid mixtures. The ferrous ion/peroxide redox system appears to be the best procedure overall, since it is inexpensive and environmentally innocuous. The best grafting frequency obtained was about one graft per 800 anhydroglucose units in the cellulose. High molecular weight poly(methyl methacrylate) polymers were made, with the grafted species larger than the corresponding homopolymers.
Electrokinetic properties of acrylic acid‐ and methacrylic acid‐grafted polypropylene during chemically initiated graft copolymerization
Authors: Lokhande H. T. , Thakar V. S. , Shukla S. R.
Published: April 2003

Electrokinetic properties such as zeta potential (ζ), surface charge density (σ) and surface conductivity (Ks) of polypropylene fibers and those grafted with acrylic acid and methacrylic acid have been studied using the streaming potential method. At pH 7, the zeta potential of −58.5 mV for control fibers reduced with increase in the amount of acrylic acid (16.2%) and methacrylic acid (28.2%) grafts to −38.15 mV and −38.30 mV, respectively. The drop in the negative zeta potential value is attributed to rendering polypropylene hydrophilic. The acrylic acid graft was found to be more effective than the equivalent amount of methacrylic acid graft in this respect due to the different chemical characters of the two graft copolymers. The negative zeta potential was also reduced to a considerable extent when cationic dye solution was streamed through the grafted polypropylene fibers, which is attributed to the deposition of dye cations on the negatively charged surface of the grafted fibers. The results on surface charge density and surface conductivity also indicated the hydrophilic character of grafted polypropylene.
Impregnation of mortars with monomers and their radiolytic polymerization
Authors: Gadalla Ahmed M. , El‐Derini Mohamed E.
Published: April 2003

Mortars were cured for a sufficient period to give sufficient strength and were then dried to remove the free water without dehydrating the compounds formed. Dried specimens were evacuated and impregnated with a mixture of styrene and acrylonitrile monomers which gives high mechanical properties after polymerization. Positive pressure was then applied, and polymerization was done radiolytically. The effect of degree and period of evacuation, the positive pressure and the irradiation dose on monomer loading, tensile and compressive strength were studied, and the optimum operating conditions were established. The achieved strength was correlated with the fraction of open pores impregnated. The composites investigated have the same volume fraction of mortar, and the polymer is added at the expense of the open porosity causing nearly an exponential increase in strength. Only 80% of the open pores were filled with polymers due to the difference in density between the polymer and the monomer, loss of monomer, and the presence of entrapped gas consisting of residual air and residual water vapor and monomer vapor, as well as due to the inability to fill all the micropores with monomer. A compressive strength four times that of plain mortar and a tensile strength eight times that of plain mortar were achieved.
Hydrolysis of dextrin in the presence of 12‐tungstosilicic acid
Authors: Arai Kenichiro , Ogiwara Yoshitaka
Published: April 2003

Hydrolysis of dextrin in the presence of 12‐Tungstosilicic acid was investigated, and the acid was found to show an approximately two times higher catalytic activity than did hydrochloric acid. From the comparison of degree of dissociation of 12‐tungstosilicic acid with that of hydrochloric acid, examination of the influence of the ionic strength on the reaction rates, analysis of the reaction products, and evaluation of activation parameters of the reaction, it was assumed in conclusion that the higher catalytic activity of 12‐tungstosilicic acid resulted from a “concentration effect” due to the complex formation of the heteropolyanions with dextrin molecules, and from the effect of its higher ionic strength, but not from the effect of direct participation of the heteropolyanion to the elementary reaction process.
Durability of adhesive bonds between glass or metal substrates and a polybutadiene–polyurethane
Authors: Liang Fasi , Dreyfuss P.
Published: April 2003

The durability of polybutadiene–polyurethane joints to glass or metals in water at elevated temperatures was studied. The effects of silane pretreatment of the surface and of surface morphology on adhesion were examined. The durability of the joint was related to the number of chemical bonds that could form between the polyurethane and the surface and to the type of surface treatment given to the surface. Proper treatment led to significant enhancement of durability of the joints.
Epoxy resin cure. II. FTIR analysis
Authors: Smith Robert E. , Larsen Fred N. , Long Charles L.
Published: April 2003

Fourier transform infrared (FTIR) spectroscopy is used to determine the cure rate of an epoxy resin consisting of Tetraglycidyl‐4,4′‐diaminodiphenyl methane (TGDDM) and diaminodiphenylsulfone (DDS). Cure rates at 120 and 160°C are shown to increase noticeably when 1% BF3–MEA is added to either TGDDM to TGDDM plus DDS. Fluoroboric acid is shown to increase the cure rates even more than the BF3–MEA. These Results combined with the NMR results in the accompanying article indicate that BF3–MEA is not a catalyst for epoxy resin cure. Instead it is rapidly hydrolyzed to fluoroboric acid which acts as the catalyst.
Resins containing extractants: Morphology of polymers prepared by polymerization of vinyl monomers in the presence of uranium‐selective extractants
Authors: Belfer S. , Egozy Y. , Korngold E.
Published: April 2003

The effect of a selective organophosphours extractant on the structure and properties of crosslinked polymers was studied. The extractant, incorporated in the polymerization mixture, affected the formation of the polymer. The uranium capacity of the resin was directly proportional to the amount of extractant. The use of scanning electron microscopy showed that the polymers are macroporous and that the porosity depends on the amounts of extractant and crosslinking agent.
Dependence of electrical breakdown on spherulite size in isotactic polypropylene
Authors: Ceres B. V. , Schultz J. M.
Published: April 2003

A self‐seeding technique, coupled with isothermal crystallization, was used to prepare isotactic polypropylene specimens of varying spherulite size, but of constant crystallinity and lamellar thickness. The latter quantities were also varied by changing the isothermal crystallization temperature. The electrical lifetime at constant applied voltage, in a point‐plane geometry, was measured. It was found that the electrical lifetime decreased with increasing spherulite size and, more weakly, with decreasing crystallinity (at a given spherulite size).
The effect of coatings on the surface precipitation of oilgomeric crystals in poly(ethylene terephthalate) films
Authors: Perovic A. , Murti D. K.
Published: April 2003

Crystalline particles of cyclic oligomers are formed on the surface of poly(ethylene terephthalate) (PET) films during heat treatment or exposure to solvent vapor. The formation of crystals of oligomers due to heat treatment can be prevented by depositing onto the PET films morphologically continuous coatings of various elements. The critical thickness of the coating which effectively stops nucleation of these crystals depends on the element deposited under given experimental conditions. In the case of solvent (methylene chloride) exposure, the most important factor preventing oligomer crystallization was the chemical nature of the element used as a coating.
Crystalline morphology of polypropylene and rubber‐modified polypropylene
Authors: Jang B. Z. , Uhlmann D. R. , Sande J. B. Vander
Published: April 2003

The crystalline morphology of injection‐molded polypropylene (PP), its relationship with crazing, and the effects of various impact modifiers on the morphology, crystallization, and fusion of PP have been studied. The highly oriented skin layer of an injection‐molded tensile bar after deformation was found to be free from crazing in contrast to the heavy craze density in the randomly oriented spherulitic core zone. Reasons for the difficulty in craze nucleation in a preoriented zone are given in light of Argon's theory of craze initiation. Addition of a rubbery phase results in an irregular texture of spherulite, smaller spherulitic diameter, and decrease in the degree of undercooling, but no appreciable change in heats of fusion and crystallization other than a trivial volume effect. The rubbery phase is not pushed by the melt–solid interface to relocate to the interspherulitic boundaries. Rather, it is engulfed by the growing melt–solid interface, leaving behind a random spatial distribution of rubber particles in the PP matrix.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. V. Studies on thermal behavior
Authors: Bhattacharyya S. N. , Maldas D.
Published: April 2003

The thermal behaviors of cellulose acetate, either grafted or ungrafted, were studied. A thermogram of cellulose acetate when grafted with acrylamide is characterized by an endothermic peak at 340°C. If, however, styrene is grafted, the thermogram shows two characteristic exothermic peaks at 330 and 420°C. A thermogram of the mixed graft comprising both acrylamide and styrene, on the other hand, is characterized by only one exothermic peak at 420°C. A consideration of various thermal data indicates that cellulose acetate when grafted is comparatively more stable than when not grafted. Again, styrene is found to be more effective than acrylamide in increasing the stability.
Mechanical properties of blends of nylon 6 with a chemically modified polyolefin
Authors: Chuang Hsiao‐Ken , Han Chang Dae
Published: April 2003

Both tensile and impact properties were measured of a heterogeneous polymer blend system, consisting of nylon 6 and a chemically modified polyolefin, DuPont CXA3095, which is an ethylene‐based multifunctional polymer. It was found, from the tensile testing, that the blends exhibited no signs of necking, and the addition of a soft resin (CXA3095) reduced the modulus and the tensile strength of nylon 6, whereas the percent elongation at break went through a minimum. When 20 wt % of CXA3095 was added to nylon 6, the impact strength was increased approximately three times. When the factors describing the interfacial adhesion were incorporated, the existing models for predicting the tensile modulus of blends were found to describe the experimental data rather well. In order to help explain the mechanical behavior observed, photomicrographs were taken of the fracture surfaces, using a scanning electron microscope.
Differential scanning calorimetry studies of the cure of carbon fiber–epoxy composite prepregs
Authors: Morgan Roger J. , Walkup Connie M. , Hoheisel Tom H.
Published: April 2003

Diaminodiphenyl sulfone (DDS) cured tetraglycidyl‐4,4'‐diaminodiphenyl methane (TGDDM) epoxies, whose cure reactions are accelerated by BF3:amine catalysts, are the most common composite matrices utilized in aerospace high performance, fibrous composites. To process reproducible composites requires an understanding of the cure reactions and how these reactions are modified by the BF3:amine catalysts. In this article we report systematic differential scanning calorimetry (DSC) studies of (i) the constituents of BF3:NH2C2H5‐catalyzed TGDDM–DDS epoxies and their mixtures, (ii) the effect of BF3:NH2C2H5 concentration on the cure reactions, (iii) the nature of the catalyzed cure reactions, and (iv) the environmental sensitivity of the catalyst. DSC studies are also reported on the cure reaction characteristics and environmental sensitivity of commercial C fiber–TGDDM–DDS epoxy prepregs.
Oxidative skeleton breaking in epoxy–amine networks
Authors: Bellenger V. , Verdu J.
Published: April 2003

The photo and thermal oxidation of various epoxide–amine tridimensional polycondensates is studied by IR spectrophotometry and DSC. The network degradation results in a decrease of the glass transition temperature (Tg), which is correlated with the quantity of amide groups formed. For each system, the relative yield in skeleton breaks increases with the intensity of internal stresses. A mechanism involving the β scission of α amino alkoxy macroradicals resulting from oxidation of constrained segments of the network is proposed.
Mechanical properties of clay coating films containing styrene–butadiene copolymers
Authors: Parpaillon M. , Engström G. , Pettersson I. , Fineman I. , Svanson S. E. , Dellenfalk B. , Rigdahl M.
Published: April 2003

The mechanical properties of clay‐based pigmented coating films bonded with a series of carboxylated styrene–butadiene latex binders have been investigated. The in‐plane tensile strength and the elongation at rupture increased with increasing amount of polymeric binder. It is suggested that this is due to an improvement in stress transfer through the structure. The mechanical behavior of the films was furthermore found to be strongly related to the properties of the polymeric binder at the usage temperature. In torsional pendulum experiments an increase in the glass transition temperature of the polymeric binder was observed when it was incorporated in the coating film. This is interpreted as being the result of a decrease in the segmental mobility of the polymer molecules due to the presence of the clay particles, i.e., due to the interaction between the clay pigments and the binder. The interaction was, however, less noticeable in experiments using an NMR (nuclear magnetic resonance) technique. If the clay was replaced by calcium carbonate, a strong interaction, as measured using NMR, was observed between CaCO3 and the styrene–butadiene polymer, although the in‐plane mechanical strength and ductility were reduced. A structural model accounting for some of the observed differences in mechanical behavior between clay‐based and CaCO3‐based coating films is suggested.
Overall NCO/OH ratio and microphase separation in urethane elastomers
Authors: Nierzwicki W.
Published: April 2003

Several polyurethanes were prepared from poly(ethylene adipate) glycol, 4,4′‐diphenylmethane diisocyanate (MDI), and 1,4‐butanediol. The overall NCO/OH ratio was allowed to vary from 0.94 to 1.21. Thus, the obtained elastomers differed in the amount of allophanate groups and perfection of microphase separation. These effects were studied by dielectric and pulsed NMR techniques. The results show that quite subtle effects concerning molecular mobility and its restriction due to interfacial region, perfection of the separation, and inadequacy of thermomechanical measurements can be investigated in the presented way.
Water permeation in polymer films. VII. Polyimide/Teflon FEP laminates
Authors: Sacher E. , Susko J. R.
Published: April 2003

Permeation parameters were obtained for various commercial polyimide/Teflon FEP laminates. Permeation coefficients, predicted from data obtained separately on each component of the laminate, match closely those found experimentally. The diffusion and solubility coefficient values, which are not amenable to such predictions, demonstrate that closely similar permeation coefficient values may be obtained from widely different diffusion and solubility coefficient values.
Behavior of polymers containing spiroorthoester or bicycloorthoester structure under EB and X‐ray irradiation conditions
Authors: Tanigaki Katsumi , Saigo Kazuhide , Ohnishi Yoshitake , Kato Hitoshi , Mizutani Kiyokazu , Ogasawara Takahisa , Endo Takeshi
Published: April 2003

Reaction behavior of spiroorthoester and bicycloorthoester to EB and X‐ray irradiations has been studied on the basis of infrared spectroscopic analysis. The polymers containing these functional groups showed markedly high sensitivity to EB and X‐ray. The formations of CO and OH after exposure indicate that these functional groups react through ring opening even in the absence of any cationic catalyst. In the high energy‐induced reaction, sensitivity and post‐irradiation polymerization effect were found to be greatly influenced by the polymer structure, different from those observed in the cation‐induced reaction.
Mechanical behavior of poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends
Authors: Rim P. B. , Runt J.
Published: April 2003

The mechanical properties of compatible poly(ε‐caprolactone)/poly(styrene‐co‐acrylonitrile) blends were studied for samples prepared from both the melt and solution. The mechanical response was observed to be primarily dependent upon the variation of the glass transition temperature with blend composition. For certain compositions, varying the sample preparation scheme resulted in specimens of different modulus. This behavior was associated with differences in the degree of crystallinity.
Analysis of the theoretical methods of calculations of ideal fiber birefringences
Authors: Włochowicz Andrzej , Janicki Jarosław , Rabiej Stanisław
Published: April 2003

Based on the equation carried out previously, theoretical birefringence has been calculated for selected synthetic fibers, taking into account intermolecular interactions. The calculation has been carried out using bond polarizabilities given by Denbigh [Trans. Faraday Soc., 36, 936 (1940)] and Pietralla [J. Polym. Sci., Polym. Phys. Ed., 18, 1117 (1984); 20, 1193 (1982)]. Large discrepancies of Δnid for polyamides between theoretical and experimental values have been found. The necessity for elaborating a new method of birefringence calculations has been pointed out.
Dye leveling in PET fibers. II. Mathematical model
Authors: Simal Abigail Lisbão , Bell James P.
Published: April 2003

A mathematical model is developed for the dye leveling process. Good agreement between experimental and theoretical data supports the validity of the proposed model. Also, the applicability of the proposed model is shown through its effectiveness in predicting leveling times, when the working temperature is above the Tg of the fibers. The results demonstrate that chain mobility is a prerequisite for rapid leveling, and that morphological changes in the fiber during the migration process are important and must be considered.
Effect of aggregation states on some properties of PVC solids and melts
Authors: Ajji A. , Jérémie G. , Rudin Alfred , Schreiber H. P.
Published: April 2003

Plasticized compounds of poly(vinyl chloride) (PVC) have been prepared using PVC polymer as supplied and as recovered from solutions in tetrahydrofuran. Mechanical properties and melt elasticity measurements were found to vary significantly among these compounds. It is proposed that the solid‐state characteristics and melt elasticity parameters in these compounds depend on the state of chain entanglement and that the entanglement state can be modified significantly by procedures such as used here. Annealing experiments have shown that the rates of attaining property equilibria—symptomatic of equilibrium entanglement states—are dependent on diffusion processes. Neither solution‐modified nor control PVC compounds are in steady states when first tested; consequently, time‐dependent property variations may be expected as morphological steady states are attained at conventional use temperatures for PVC compounds. The present study extends to PVC the principles of entanglement network modification through solution, or shearing processes, as a means of selecting preferred property balances in melt processing and mechanical properties. That principle had earlier been shown to apply to polyethylenes.
Surface characterization of a titanate coupling agents modified sepiolite
Authors: Arroyo M. , Iglesias A. , Perez F.
Published: April 2003

The surface treatment of a sepiolite with two different titanate coupling agents has been studied. The results obtained from several chemical and physical analytical methods used for the organophylized surface characterization have shown a monolayer reaction has taken place. An attempt to relate the degree of organophylization to the specific surface decrease of filler has been made.
Radiation‐induced graft copolymerization of methacrylic acid onto polypropylene fibers. I. Effect of synthesis conditions
Authors: Mukherjee A. K. , Gupta B. D.
Published: April 2003

The gamma radiation‐induced graft copolymerization of methacrylic acid onto polypropylene fibers was investigated by simultaneous—irradiation technique. The effect of various synthesis conditions on the graft content was studied. At a constant dose, the percent grafting was found to be higher at low dose rate. For all the dose rates, a linear increase in the grafting was observed up to 0.25 Mrad, beyond which the grafting levelled off. Percent grafting also increased continuously with increasing monomer concentration up to 4.0 mol/L, but a linear increase in grafting was observed only up to 2.0 mol/L. The initial rate of grafting increased with the increase in dose rate and monomer concentration. The dependence of rate of grafting on dose rate and monomer concentration was found to be 0.70 and 1.71, respectively. The effect of liquor ratio upon grafting was also studied.
Radiation‐induced graft copolymerization of methacrylic acid onto polypropylene fibers. II. Effect of solvents
Authors: Mukherjee A. K. , Gupta B. D.
Published: April 2003

Graft copolymerization of methacrylic acid onto polypropylene fibers by simultaneous‐gamma ray irradiation technique was carried out. The effect of various solvents on grafting was studied. The results have been presented in terms of swelling behavior of polypropylene fiber and the extent of homopolymerization. An accelerative effect upon the rate of grafting was observed when benzene was partly replaced by methanol. At the dose rate of 24 rad/s and monomer concentration of 3 mol/L, a maximum in the rate of grafting was observed with 40% methanol fraction in the benzene–methanol mixture. However, a further increase in the methanol fraction in the solvent mixture resulted in a sharp decrease in the rate of grafting. No grafting was observed in pure methanol. This behavior has been explained in terms of the inhibitory action of methanol for polymerization of methacrylic acid and the extent of swelling of polypropylene fiber in various compositions of benzene–methanol mixture.
Theory of tack of pressure sensitive adhesive. I
Authors: Mizumachi Hiroshi
Published: April 2003

If the tack of a pressure‐sensitive adhesive is closely related to the rolling motion of a ball on the material, it is more scientific to express tack in terms of the rolling friction coefficient, which depends on the physical properties of the materials, and not on any trivial conditions of measurements. It is shown that the rolling friction coefficient of a pressure‐sensitive adhesive can experimentally be determined from the pulling cylinder method much more easily than the rolling ball method and that we can theoretically calculate the rolling friction coefficient by making some assumptions, concerning deformation and failure of a pressure‐sensitive adhesive.
Aromatic ionomer membranes. I. Physical and mechanical properties
Authors: Besso E. , Legras R. , Eisenberg A. , Gupta R. , Harris F. W. , Steck A. E. , Yeager H. L.
Published: April 2003

The physical properties of a new class of ionomers comprising a semirigid polyphenylene ether backbone were investigated. The material was studied principally in the form of films of ca. 150 μm micrometers in thickness. The study focused on material of 600 equivalent weight. Torsion pendulum results showed a significant increase in the glass transition temperature of the ionomer relative to that of its ester precursor but gave no evidence of ionic clustering. Stress–strain studies performed both in water and in 20% KOH solution at 80°C indicated that the mechanical properties of the material remain stable under these conditions. Differential scanning calorimetry was used to investigate both the high temperature behavior and the water uptake of the ionomer films. The behavior of this ionomer at high temperature and in an alkaline solution is of particular interest in view of the possible use of these films as separators in an alkaline electrolysis cell.
Effects of various factors on the formation of high molecular weight polyamic acid
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei
Published: April 2003

The reaction of pyromellitic dianhydride (PMDA) and aromatic diamine in an aprotic solvent such as dimethylacetamide (DMAc) gives a solution of poly(amic acid). The effects of certain variables on the polymerization and some additives on the stability and imidization of the poly(amic acid)s were studied. It was found that the addition of PMDA portionwise to the solution of diamine always keeps the excess diamine in solution and enables one to obtain the highest molecular weight of poly(amic acid). When the addition process was reversed, either by the change or dehydration of solvent, a high molecular weight was not attained. The inevitable water in the solvent or the reaction medium is the major factor, and the more the water content in the solvent or the reaction medium, the larger is the probability of destruction of PMDA during the reaction and hence low molecular weight is obtained. If very pure monomers were used in the polymerization, the 1:1 of molar ratio is the optimum value. Excess diamine or dianhydride results in the exchange reaction with poly(amic acid) and causes a rapid degradation of polymer chain. This exchange reaction was proved by NMR measurements. The presence of electrophilic agents or the nucleophilic agents containing active protons in the poly(amic acid) solution promotes the decomposition of polymer and causes the brittleness of polyimide film in the curing process. Using acetic anhydride (A) to convert the poly(amic acid) to polyimide, pyridine (P) can protect the polymer chain from the nucleophilic attack by the anhydride. The mixture with proper ratio of A/P (1/1–15/1) can be used as good dehydrating agents.

Meanwhile, according to the results to the results of experiments, we suggested the probable reaction mechanisms about how the water, amine, and anhydride destroy the polyamic acid chains.
The synthesis and properties of tetrafunctional epoxy resins
Authors: Liu Wen‐Liang , Pearce Eli M. , Kwei T. K.
Published: April 2003

N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylalkane epoxy resins with alkyl substituents on the methylene carbon were synthesized and characterized. The thermal and dynamic mechanical properties of these resins when cured with diaminodiphenylsulfone were compared with those of the cured unsubstituted epoxy resin. Although the resins have similar structures, the cured resin from the unsubstituted epoxy has the higher polymer decomposition temperature and glass transition temperature. The substituted epoxy resins have higher dynamic Young's moduli and loss moduli.
Effect of coagulation medium on properties of sulfonated polyvinylidene fluoride membranes
Authors: Bottino A. , Capannelli G. , Munari S.
Published: April 2003

The performance and the structure of sulfonated polyvinylidene fluoride membranes prepared in different coagulation media were investigated. Several pure organic compounds and mixtures of some of them with water were used as coagulation media. The membrane were tested in an ultrafiltration laboratory unit with dextran aqueous solutions. The overall structure of the membranes was examined with the aid of the scanning electron microscope. The effect of temperature of the coagulation medium on the properties of the membranes were also investigated.
Coordination behavior of cyanide ion to hemin uncomplexed and complexed with several synthetic polymer ligands
Authors: Kokufuta Etsuo , Watanabe Hiroshi , Saito Kiyoshi , Nakamura Isei
Published: April 2003

Hemin (H) (ferri–protoporphyrin IX chloride) was complexed in aqueous media with the following polymer ligands; poly(L‐lysine), poly(L‐histidine), branched polyethyleneimine, and two copolymers of 1‐vinyl‐2‐pyrrolidone with 1‐vinylimidazole and with 1‐vinyl‐2‐methylimidazole. The resulting water‐soluble complexes were either the five‐ or six‐coordinate hemichromes, respectively, which coordinated one or two ligand units in polymer to ferri—protoporphyrin IX (FP). The coordination behavior of cyanide ion to the hemichromes and also to H was investigated by means of spectroscopic titration method. It was found that one cyanide ion binds not only to the five‐coordinate hemichromes, but also to the six‐coordinate ones by the ligand exchange reaction with the cyanide ion, whereas two cyanide ions coordinate to H, which is free from polymer ligand able to occupy the coordination site(s) of FP. Morever, the degree of saturation of the iron(III) in FP with cyanide ion for all the hemichromes was found to be much larger than that for H. These results indicate that the ability of FP to coordinate cyanide ion is closely associated with whether one coordination site of FP is occupied by polymer ligand or not.
Radiation‐Induced graft copolymerization of methacrylic acid onto polypropylene fibers. V. Mechanical properties
Authors: Mukherjee A. K. , Gupta B. D.
Published: April 2003

Mechanical properties of polypropylene‐g‐poly(methacrylic acid) fibers, prepared by graft copolymerization of methacrylic acid onto polypropylene fiber using simultaneous gamma ray irradiation technique, were evaluated. In general, an improvement in the mechanical behavior of the polypropylene fiber by grafting was observed. Denier and initial modulus of the fiber showed a linear increase with the percent graft, and elongation showed an opposite trend. The results have been explained in terms of reinforcing effect of poly(methacrylic acid) grafts and reduction in the segmental mobility of the polymeric chains. Tenacity also increases up to certain graft level, beyond which a sharp decrease occurs, probably due to the influence on the compactness of the macromolecular chains with the further grafting.
Morphological studies on the adhesion mechanism of pressure‐sensitive adhesives
Authors: Hino Kinnosuke , Hashimoto Hatsujiro
Published: April 2003

The breaking process of the thin film of pressure‐sensitive adhesives which are blends of natural rubber and the pentaerythritol ester of hydrogenated rosin and its surface structure after peeling off have been studied by electron microscopy. The dynamic observation of breaking process of the adhesives during the peeling has also been done by optical microscopy. The fibril structure with diameter of 50‐100 Å was observed under the breaking process of the thin film and on the surface after peeling off the adhesive tape consisting of 40‐60 wt % of resin. The previously proposed mechanism of adhesion which is based on the dynamic behaviors of fibrils and easy flow regions in the adhesives is confirmed by the electron microscopic observation.
Vinyl chloride–vinyl acetate kinetic modeling. I. Determination of radical efficiency factor
Authors: Heffelfinger Michael T. , Langsam Michael
Published: April 2003

Using dead end polymerization procedures, the copolymerization of vinylchloride–vinyl acetate was studied in laboratory scale reactors. Predictive kinetic models based on modified Hamielec equations were developed which were valid up to the limit of the experiments, 35% conversion. The efficiency factor (f) for the t‐butylperneodecanoate initiator was determined for a range of initiator concentrations in a comonomer mixture.
Removal of nonionic surfactant by systems based on chloromethylated polystyrene–poly(ethylene glycol)
Authors: Tashiro Tatsuo
Published: April 2003

For the purpose of obtaining compounds which can remove nonionic surfactants in water, chloromethylated polystyrene (CMPS) was allowed to react with triethylene glycol monomethyl ether (3EGMME), tetraethylene glycol (4EG), poly(ethylene glycol) (PEG) 200, 400, 600, 1000, and 1500. The amount of PEG groups combined with CMPS decreased with an increase in the molecular weight of PEG. The ability of the product to remove polyethylene glycol mono‐p‐nonyl phenyl ether (NP, n = 10), a nonionic surfactant, solutes in water was greater in the product with PEG of greater MW than that with PEG of smaller MW, and in the product with more PEG groups (mol/g prod.) than in that with less PEG groups. The removal behavior of the products conformed to Freundlich's adsorption formula. Constants of the formula, the effect of temperature on the constants, the effect of combined PEG groups on the removed amount, and the removal manner were studied.