bluuebunny/crossref_metadata_2025 huggingface dataset:
Reactions de sulfopropylation, cyanoethylation et greffage d'acrylonitrile sur l'alcool polyvinylique et le poly[ethylene methylenebis(4‐phenyl carbamate)]
Authors: Galin J. C.
Published: April 2003

By using “dimsyl sodium” or sodium hydride as metallating agent, it is possible to obtain without degradation the sodium derivatives of poly(vinyl alcohol) or of polyurethanes in homogeneous solution in dimethylsulfoxide or dimethylformamide. These metallated polymers have been successfully reacted with calculated amounts of propane sultone and then of acrylonitrile to produce sulfonated, cyanoethylated, and acrylonitrile graft copolymers. The copolymers thus obtained present two characteristic properties: (1) they are anionic polyelectrolytes offering a good affinity toward cationic dyes, and (2) they are compatible, either in solution or in solid state, with acrylic and modacrylic fiber‐forming polymers.
Transport of fixed gases in radiation‐stabilized poly(vinyl chloride)
Authors: Nakagawa Tsutomu , Hopfenberg H. B. , Stannett V.
Published: April 2003

Poly(vinyl chloride) was reacted with sodium N‐methyl dithiocarbamate to produce a modified PVC containing N‐methyl dithiocarbamate of varying degrees of substitution. The resulting adducts were markedly more stable when subjected to γ‐radiation than the unmodified PVC. The transport parameters (permeability, solubility, and diffusivity) of fixed gases were determined in modified and unmodified films. Although the radiation stability was dramatically improved by this novel substitution, the barrier properties of the PVC were only slightly changed by the controlled substitution of N‐methyl dithiocarbamate.
Radiation‐induced sulfoxidation and sulfochlorination of powdery polyethylene produced by radiation process
Authors: Konishi Kunio , Yamaguchi Kouichi , Takehisa Masaaki
Published: April 2003

Gamma radiation‐induced sulfoxidation and sulfochlorination of the high specific surface area powdery polyethylene which was produced by radiation‐induced polymerization of ethylene at room temperature were studied and were compared with sulfonation by fuming sulfuric acid. In these reactions the effect of surface area on the chemical reactivity was observed to a certain degree. In gamma radiation‐induced sulfochlorination, it was elucidated that as the reaction proceeds, the ratio of SO2Cl to Cl introduced into the polymer decreases, which can be explained by the difference between the diffusibilities of SO2 and Cl2 molecules through sulfochlorinated and/or chlorinated polyethylene. Crystallinity, melting temperature, and density of the sulfochlorinated polymers were measured and are discussed.
Factors in rubber compounds affecting the adhesion of polyester tire cords
Authors: Iyengar Y.
Published: April 2003

Several factors in rubber stocks were demonstrated to be important in the adhesion of polyester tire cords to rubber compounds. The retained adhesion of polyester tire cords, determined after heat‐aging laboratory cord–rubber samples at elevated temperatures, was improved by (a) eliminating the sources of amines in the elastomers and compounding ingredients, (b) reducing the moisture content of the stocks, (c) increasing the overall water vapor permeability (WVP) of the cord–rubber composite, and (d) lowering the modulus of the stock. Sulfenamide cure accelerators and water were found to be synergistic in reducing the retained adhesion of polyester cord after in‐rubber aging at high temperatures. The harmful effects of amines released from sulfenamides during curing and heat aging were eliminated by compounding the stocks with accelerators that do not form amines. Aliphatic diamines present as nonrubber components in natural rubber (NR) were shown to be detrimental to adhesion. Since synthetic polyisoprene rubber (IR) does not contain any nonrubber components, IR stocks containing the nonamine accelerator benzothiazyl disulfide (MBTS) showed excellent retained adhesion to polyester cords. A recently developed nonamine‐type accelerator gave adhesion essentially equal to MBTS but showed excellent scorch safety and high stock modulus typical of sulfenamides. The retained adhesion in IR stocks after heat aging was less dependent on moisture level and stock modulus than in NR stocks. Finally, examples of practical rubber compounds giving improved retained adhesion to polyester tire yarns are given.
The relation between melt flow properties and molecular weight of polyethylene
Authors: Saeda Shigeru , Yotsuyanagi Junji , Yamaguchi Kinya
Published: April 2003

The non‐Newtonian behavior of commercial linear polyethylene samples and their fractions were studied at 190°C. The viscosity η versus shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} curves of whole polymers could be superimposed onto a single master curve despite the variations of their molecular weights and molecular weight distributions. For fractions, however, the same master curve was inapplicable, and the sensitivity of the viscosity to shear rate was found to be greater than those of the whole polymers. The zero‐shear viscosities η0 of fractions were related to the 3.42 power of the weight‐average molecular weight Mu as follows:

For whole polymers, the zero‐shear viscosities were found to be considerably higher at the same Mw and markedly lower at the same z‐average molecular weight Mz than those of the fractions. Thus, it was concluded that η0 corresponds to an average of molecular weight between Mw and Mz. It was found that the molecular relaxation time τ is proportional to Mz5.3 for whole polymers and to η0Mw for fractions. Using these relations it was possible to relate the flow ratio, the ratio of flow rates at two different shear stresses, with the molecular weight distribution.
A new apparatus for measuring various properties of plastics using C specimens
Authors: Ohishi F.
Published: April 2003

A new apparatus for measuring various properties of plastics is proposed. Using a split circular ring‐type specimen (C specimen), displacement L, tension P, and fringe order N are measured by means of a differential transformer, a load cell, and a polarizeranalyzer. The Young's modulus and photoelastic sensitivity of samples can be estimated from L, P, and N. Experiments are carried out in the environments of air, water, oils, and chemical reagents under‐temperature controlled conditions. Typical data are, presented showing the applications of this apparatus to the determination of the heat distortion temperature and the effect of temperature on the rigidity and photoelastic properties, to the simultaneous measurement of stress relaxation and birefringence and of creep and birefringence, and to the continuous measurement of resistance to chemical reagents and ultraviolet rays.
Cellulose graft copolymers. III. Effects of oxygen on graft copolymerization of ethyl acrylate with γ‐irradiated cellulose
Authors: Nakamura Yoshio , Hinojosa Oscar , Arthur Jett C.
Published: April 2003

The effects of oxygen on graft copolymerization of ethyl acrylate from methanol–water systems with γ‐irradiated fibrous cotton cellulose were investigated by electron spin resonance spectroscopy and by the formation of cellulose–poly(ethyl acrylate) copolymer. The concentrations of free radicals in cellulose irradiated dry in an atmosphere of nitrogen at 25°C decreased during postirradiation storage in nitrogen or oxygen. The concentration of free radicals in the irradiated cellulose, moisture regain of the irradiated cellulose, and formation of cellulose–poly(ethyl acrylate) copolymer decreased with increase in temperature and time of postirradiation storage and to a greater extent when stored in oxygen rather than in nitrogen. From the decrease in moisture regain of irradiated cellulose during postirradiation storage, it was concluded that increased intermolecular bonding occurred in irradiated cellulose during storage in both nitrogen and oxygen atmospheres. When irradiated celluloses which had been stored in either oxygen or nitrogen were copolymerized with ethyl acrylate at 60°C, less formation of copolymer was observed than when the copolymerization reactions were conducted at 25°C. It was concluded that there was no evidence for the formation or decomposition of cellulose peroxides during these reactions and that formation of graft copolymer depended primarily on the concentration of free radicals in the irradiated cellulose at the time of copolymerization.
Inhibitory action of phenols and amines in the photo‐oxidation of tetralin
Authors: Goda Kiyoshi , Tanaka Makoto , Murata Niro
Published: April 2003

The inhibitory efficiences of antioxidants (phenols and aromatic amines) were determined under irradiation for elucidation of their behavior in photo‐oxidation. We determined the ratio of termination rate constant to propagation rate constant and compared the ratio under irradiation with that in the dark. Phenols are classified into two categories with respect to their behavior under irradiation. The first is as antioxidants that have the same ratios under both conditions; the second, as antioxidants that have smaller ratios under irradiation than in the dark. We assumed the smaller ratios to be due to the following: quinones formed via the excited state of phenols by light absorption, in addition to the original phenols, participate in radical capture. Aromatic amines were also classified into two categories relative to their behavior under irradiation.
A simplified method for correction of polydispersities from gel permeation chromatography
Authors: Baker J. R.
Published: April 2003

A simple method is presented for correction of polydispersity obtained by gel permeation chromatography. The method proposed utilizes well‐characterized polystyrene standards for both instrument calibration and construction of a correction curve which is then used for calculation of weight‐average and number‐average molecular weights and polydispersity of samples to be characterized.
On the internal structure of pressure‐sensitive adhesives
Authors: Kamagata Kazuo , Kosaka Hideo , Hino Kinnosuke , Toyama Mitsuo
Published: April 2003

The internal structure of pressure‐sensitive adhesives was studied using electron microscopy and measurements of mechanical loss, tensile modulus, viscosity, stress relaxation, and critical surface tension. The adhesives were blends of natural rubber and the pentaerythritol ester of hydrogenated rosin. Compositions containing up to 40 wt‐% resin are homogeneous mixtures. The temperature dispersion of mechanical loss shows a single peak, and the peak value remains almost constant. When the resin concentration exceeds 40 wt‐%, phase separation occurs. The disperse phase is resin containing a small amount of rubber. Two peaks, or a peak and a shoulder, appear in the temperature–loss peak curves. It is postulated that one of the peaks corresponds to the phase in which resin is uniformly dispersed in the rubber and the other peak corresponds to the resin phase which contains a small amount of rubber. Evidence for homogeneity in compositions containing 40 wt‐% or less resin and of heterogeneity at higher concentrations of resin was also obtained from the electron microscope observations. The relationships between the internal structure of pressure‐sensitive adhesives and viscosity, Young's modulus, the relaxation spectrum, tack, and critical surface tension are discussed.
Photoreactive polymers. IV. The synthesis and characterization of photocrosslinkable polysulfonates
Authors: Arcesi J. A. , Rauner F. J. , Williams J. L. R.
Published: April 2003

A series of new light‐sensitive polysulfonate copolymers have been prepared by the interfacial polycondensation of mixed bisphenols and aromatic disulfonyl chlorides. The light‐sensitivity bisphenols contain the styryl ketone group. These polymers exhibit good light sensitivity, and upon exposure to light they crosslink and harden to give alkali‐ and acid‐resistant materials which are useful in photoresist applications.
Light scattering studies on the ripening of viscose solution
Authors: Ghosh Kalyan K.
Published: April 2003

Investigations were made on cellulose xanthate molecular weights by light scattering during the ripening of the solutions of (a) viscose‐containing colored thio salts and (b) pure cellulose xanthate separated from viscose. Though an apparent reduction in molecular weight was recorded with time of ripening for the viscose solution, no such fall was observed with pure cellulose xanthate. The apparent fall of molecular weight in the case of viscose has been shown to be due to the increasing absorption of the incident beam and to the change in the value of dn/dc with progressive color formation. Reproducible results can be obtained for cellulose xanthate solutions freed from color. Intrinsic viscosity of the viscoses and the degree of polymerization (D.P.) of the regenerated cellulose from viscoses during ripening were also measured and found to be constant. The results indicate that no degradation of alkali cellulose molecule takes place during the ripening process, irrespective of the state of degradation of alkali cellulose from which the viscose is made.
Vapor phase polymerization of vinyl chloride
Authors: Kahle G. R. , Moberly C. W.
Published: April 2003

A study of the polymerization of vinyl chloride was made at conditions under which the monomer exists in the gas phase. In the presence of a bed of poly(vinyl chloride) particles, free‐flowing product was obtained. By using free‐radical initiators, such as dialkylperoxy dicarbonates or acetylcyclohexane sulfonyl peroxide, high initiator productivities were obtained in reaction periods of 1.5 to 3 hr. Although some modifiers, such as ethyl bromomalonate and bromoform, were demonstrated to lower molecular weight, satisfactory molecular weight modification was accomplished by adjusting polymerization temperature. Several peroxy compounds of different reactivity were studied. Hydrocarbon additives improve the polymerization rate. It is believed that the hydrocarbon and initiator are absorbed on the PVC particle surface and allow the monomer concentration to be increased at the polymerization locus. PVC particles of small size may be prepared in a liquid bulk polymerization for use as seed polymer for the vapor phase process. This provides a seed of high porosity which enables one to prepare a vapor phase product with suitable plasticizer absorption. The physical properties of products prepared by the vapor phase process were evaluated in a rigid formulation.
Greffage radiochimique de l'acide acrylique sur les fibres de polyester
Authors: Bonnefis J. C. , Puig J. R.
Published: April 2003

Le greffage par irradiation directe de fibres de polytéréphtalate d'éthylène glycol en contact avec des solutions aqueuses d'acide acrylique a été étudié dans les conditions suivantes: (a) irradiation par rayonnement gamma de 60Co entre 10.000 et 100.000 rads/hr pour des doses allant jusqu'à 1 Mrad; (b) irradiation par faisceau d'électrons des fibres imprégnées, avec des doses allant jusqu'à 4,5 Mrad. Les essais utilisant les rayons gamma se sont déroulés à des températures comprises entre 0°C et 90°C. Les influences des concentrations en monomère et an inhibiteurs sélectifs de l'homopolymérisation ont permis le choix des conditions opératoires les meilleures. La vitesse initiale de greffage est une fonction complexe du débit de dose puisqu'elle passe par un maximum vers 2,5 · 105 rad par heure à la température ambiante. La vitesse de greffage qui diminue avec la dose pour éventuellement s'annuler est une fonction croissante de la température. Deux énergies d'activation globales interviennent: 5,10 Kcal/mole entre 0°C et 55°C et 1,46 Kcal/mole au dessus de 55°C. Les fibres greffées contenant jusqu'à 40% de polyacide acrylique manifestent des propriétés intéressantes vis‐à‐vis de la reprise d'humidité, de l'affinité tinctoriale et de l'électricité statique, alors que leurs propriétés mécaniques ne sont pratiquement pas affectées. Les taux de greffage des plus utiles sont compris entre 15% et 20%.
Transport properties of eastman cellulose acetate membranes: Influence of diffusant size and shape on permeability
Authors: Osterhoudt H. W.
Published: April 2003

Eastman cellulose acetate membranes (acetyl content = 40%) have been studied by means of dialysis rate experiments with uncharged permeants of selected sizes and shapes. The experimental results show that the high flux membranes exert no molecular size or shape selectivity on the transport of permeants whose molecular weights are less than 1152. The membranes used in desalination, however, are selective as to molecular size and shape. Desalination membranes, therefore, may be useful in separations where differences in size and shape are present.
Continuous flow operation in emulsion polymerization of styrene
Authors: Nomura Mamoru , Kojima Hideki , Harada Makoto , Eguchi Wataru , Nagata Shinji
Published: April 2003

The kinetics of continuous emulsion polymerization of styrene were studied theoretically on the basis of the authors' batch reaction model, and a new reaction model was proposed for continuous operation. The validity of the model was tested by experiments conducted with stirred tank reactors in series. The characteristics of the first reactor used to generate polymer particles were studied in particular detail. It was found that there was an optimum residence time for the first reactor, the value of which was quantitatively predictable from the operating variables. The most suitable combinations of several types of reactors for continuous emulsion polymerization are also discussed.
The prediction of the tensile properties of flexible foams
Authors: Lederman J. M.
Published: April 2003

An idealized model for flexible foam in tension is developed. The model includes large deformations and cell structure orientation before and after deformation. It is predicted that two quantities affect the initial modulus of an unoriented foam: the density and a cell structure parameter. Data for latex foam show that the model correctly predicts the initial tensile modulus. The model also predicts that cell structure orientation is a reasonable method for achieving a desired modulus without altering the density.
Vapor permeabilities by dynamic sorption
Authors: Osburn James O. , Kammermeyer Karl , Laine Roney
Published: April 2003

A new method of measuring the permeability of plastic films to vapors is described. The method is simple and convenient, uses general‐purpose equipment, and gives good results in a short time. It is easily adapted to vapors other than water vapor. This method is recommended for measurements of permeability where the expense of specialized equipment is not justified. Further studies on effects of parameters such as temperature, humidity, solvation of polymer, etc., are under way.
Synthesis of alternating polyamideurethans by reacting diisocyanates with N,N′‐di‐(6‐hydroxy‐caproyl)alkylenediamines and N‐hydroxy‐alkyl‐6‐hydroxycaproamide
Authors: Katayama Shitomi , Horikawa Hideichi , Ito Yoshihiro , Gomyo Noboru , Obuchi Yukio
Published: April 2003

Polyamideurethans of structures I and II were prepared by reacting N,N′‐di‐(6‐hydroxycaproyl)alkylenediamines and N‐hydroxyalkyl‐6‐hydroxycaproamide with hexa‐methylene diisocyanate and 4,4′‐diphenylmethane diisocyanate:
magnified image
where R1 is either a dimethylene or hexamethylene radical, and R2 is a hexamethylene or 4,4′‐diphenylmethane radical. Polymers I and II were of a high degree of polymerization and crystallinity, had high enough melting points for practical use, and gave colorless tough films both by dry and melt castings. The polymers from hexamethylene diisocyanate were much more crystalline and thermally more stable above the melting points than those from 4,4′‐diphenylmethane diisocyanate. Polymerization conditions and characteristic properties of the resulting polymers were studied.
The mechanism of extender action by potassium persulfate in the suspension polymerization of styrene
Authors: MacLay William N.
Published: April 2003

The contribution by potassium persulfate to suspension stability in the bead polymerization of styrene which is stabilized by hydroxyl apatite (tricalcium phosphate) powders has been studied. Potassium persulfate, when used in lieu of an anionic surfactant as the extender, causes the formation of polystyrene sulfate in the aqueous phase. This anion‐active polymer adsorbs on the surface of the hydroxyl apatite crystals and thus alters their wetting characteristics, causing them to become more effective suspension stabilizers. Polystyrene sulfates of molecular weights ranging from 2000 to 100,000 have been synthesized, characterized, and shown to be effective hydroxyl apatite extenders. The capability of polystyrene sulfate to adsorb onto hydroxyl apatite crystals is not strongly dependent upon the molecular weight of the polymeric ester. The tolerance of the system to high molecular weight polystyrene sulfate is relatively high since excess extender is taken up by dissolving in the monomer phase. The tolerance for water‐soluble polystyrene sulfate, on the other hand, is low because excess extender of this type engages in double‐layer adsorption on hydroxyl apatite, which renders the latter too hydrophilic to permit effective suspension stabilization. Use of a water‐soluble polymerization inhibitor in the suspension polymerization system has no effect on suspension stability when sodium dodecylbenzene sulfonate or preformed polystyrene sulfate is used as the extender; however, suspension stability is destroyed when the inhibitor is used with persulfate, because it prevents the formation of polystyrene sulfate. Potassium persulfate is therefore more accurately described as a precursor of the active extender, which is the mono‐ or disulfate ester of polystyrene.
Effect of surface characteristics on polymer growth on titanium trichloride catalyst
Authors: Carradine William R. , Rase Howard F.
Published: April 2003

Large sublimed leaflets of titanium trichloride have been observed over a wide range of magnification both by optical and electron microscopy under conditions such that ethylene polymerization was slow enough so that its progress could be observed in detail. After treatment with triethylaluminum, a network of cracks develops on which polymer grows upon introducing ethylene. Polymer also appears on steps, crushed areas, and cleaved edges but not on as‐grown edges. The polymer appearing on lateral surfaces was nodular in character while that growing on basal surfaces was fibrous. The physical properties of these two forms may be different, and methods for favoring one or the other are suggested.
The effects of varying the polymer composition on the cut growth characteristics of E/P/1,4 HD tire treads
Authors: Stewart C. W. , Verbanc J. J.
Published: April 2003

Experimental ethylene–propylene–1,4‐hexadiene polymers covering a range of compositions which possess satisfactory processing characteristics and economics have been evaluated in passenger car tires with emphasis on groove cracking. The tearing energy criterion was used in a laboratory test to correctly predict the groove cracking behavior of the tires made from these polymers. Road tests indicate that ethylene–propylene–1,4‐hexadiene tripolymers containing 36%–42% propylene and 1.8%–2.2% diene exhibit resistance to cut growth and abrasion which is superior to standard SBR–BR bias tires. Polymers containing more than 42% propylene or 2.2% diene were inferior in wear and resistance to groove cracking, but sufficient data are not available to pinpoint the reason.
Strain rate dependency on stress–strain relations of polypropylene
Authors: Kobayashi Akira , Ohtani Nobuo
Published: April 2003

True constant strain rate tensile tests of polypropylene up to 2% initial strain were performed to investigate the strain rate dependency of the initial stress–strain gradient dσ/dε with the aid of “slack grip.” The experimental results fairly agree with even the simplest mechanical model analysis with three parameters, showing the conspicuous strain rate dependency on the initial stress–strain gradient dσ/dε. The limiting cases corresponding to zero strain rate and strain rate of infinite magnitude, both predicted by the analysis, were experimentally verified.
Protection against intense light. I. Discussion of the usual mechanisms of energy dissipation
Authors: Prosser R. A.
Published: April 2003

The relative thermal protection offered by a series of halogenated vinyl polymers is discussed in terms of the usual modes of energy attenuation and dissipation, such as reflection, endothermic decomposition, etc. It is shown that none of these modes is so overwhelming that it alone can account for the relative thermal protection offered by these polymers.
Adsorption of polyamides and the stability of dispersion
Authors: Sato Tatsuo
Published: April 2003

The stability of red iron oxide, titanium dioxide, and carbon black dispersed in cyclohexanone and isopropyl alcohol solutions of fatty polyamides was studied by measuring adsorption, viscosity, zeta potential, and sedimentation volumes. It was found that the stability of dispersion is markedly affected by the adsorption of polyamides. The greater the amount of adsorption, the greater the stability. On the other hand, a negative adsorption impaired the stability. A stabilization mechanism of polyamide adsorption was discussed in terms of entropic repulsion, electrostatic repulsion, and van der Waal's attraction.
Rheology of shaped fiber formation
Authors: Han Chang Dae
Published: April 2003

A rheological interpretation is given for the formation of shaped fibers whose cross section is different from the spinnerette shape. For the study, a rectangular die having an aspect ratio of 6 was constructed, with dimensions 0.1 in. by 0.6 in. Measurements were then taken of the distributions of wall normal stresses at two adjacent walls of the rectangular duct. The measurements show the nonuniform distributions of wall normal stresses over the long and short sides of the rectangle, which is in accord with the nonuniform distributions of extrudate swell on both sides of the rectangle. Explanations are then given for the observed fact that extrudate swell is more pronounced at the long side than at the short side.
Studies on the ability of cellulosic materials to initiate graft copolymerization
Authors: Ogiwara Yoshitaka , Igeta Kikuji , Kubota Hitoshi
Published: April 2003

The activity to initiate graft copolymerization was investigated for various cellulose samples. Oxidation of the sample with hydrogen peroxide or sodium hypochlorite indicated a remarkable increase in the per cent grafting as well as the number of grafts. This phenomenon must be attributed to the formation of special reactive groups in cellulosic materials. However, the treatment with hot water caused a definite decrease in the per cent grafting or the number of grafts for the graft copolymerization on the sample, indicating a lower activity to initiate graft copolymerization. Accordingly, the reactive groups, once formed on the sample by oxidation, seemed to be easily decomposed by hot water. The ferric ion adsorbed on cellulose increased the per cent grafting and accelerated the formation of grafts, and the contribution of metallic ions to the initiation was recognized as one of the important factors of graft copolymerization.
Rheological properties of molten polymers. I. Homopolymer systems
Authors: Han Chang Dae , Yu Thomas C. , Kim Kwang Ung
Published: April 2003

Experimental work has been carried out to investigate the influence of molecular weight distribution and long chain branching on both viscous and elastic properties of molten polymers, using a capillary rheometer, as described in a recent paper by Han. The materials used for the study are three high‐density polyethylene samples of widely different molecular weight distributions and a low‐density polyethylene containing much long‐chain branching. For the analysis of the experimental data, and to obtain the information on the melt elasticity, the concept of the exit pressure recently advanced by Han is used. The study shows that the sample containing long‐chain branching is much more elastic than the samples containing little or no long‐chain branching, and that the broader the molecular weight distribution of the material, the more elastic the material is. These findings are in conformity with those reported in the literature. Also studied were blends of two high‐density polyethylenes having widely different molecular weight distributions. The results of the blends systems show a maximum in melt viscosity as well as in elasticity for a certain blending ratio. The results of the present study may be of considerable interest to those who are concerned with modifying the structure of polymer and also with determining optimum processing conditions.
A novel method for preparing poly(alkyl methacrylates) and poly(methacrylic acids) of varying tacticity
Authors: Chlanda Frederick P. , Donaruma L. Guy
Published: April 2003

In order to synthesize poly(methacrylic acid) and poly(alkyl methacrylates) over a wide range of polymer tacticity, the anionic polymerization of the following alkyl methacrylates (ethyl, n‐propyl, isopropyl, n‐butyl, sec‐butyl, isobutyl, tert‐butyl, n‐amyl, n‐hexyl, n‐octyl, n‐decyl, n‐lauryl, and n‐octadecyl) in toluene using phenylmagnesium bromide initiation was studied. It was found that the amount of isotactic polymer structure generally decreased as the size of the ester group increased. In all cases, the polymers had greater than 50% isotactic triad structure. Whether the polymerization was carried out at 0° or −78°C had little or no effect on the tacticity of the polymer produced. It was found that the poly(alkyl methacrylates) produced could be hydrolyzed in concentrated sulfuric acid to poly(methacrylic acid). The poly(methacrylic acid) produced in the hydrolysis could be esterified with diazomethane to give poly(methyl methacrylate) or with diazoethane to give poly(ethyl methacrylate) with the same tacticity as the poly(alkyl methacrylate) from which the poly(methacrylic acid) was derived. It is possible, therefore, to produce poly(alkyl methacrylates) of a desired tacticity by polymerizing the appropriate monomer, hydrolyzing, and reesterifying the resultant poly(methacrylic acid) with a diazoalkane to give the desired poly(alkyl methacrylate).
Synthetic biologically active polymers. VI. Sulfonamide‐ and sulfone‐dimethylolurea copolymers
Authors: Dombroski John R. , Donaruma L. Guy
Published: April 2003

Dimethylolurea was found to copolymerize with a number of sulfonamides and sulfones (Ia–h) to yield oligomeric condensation products (IIa–h). The preparation and characterization studies relevant to these materials are described. Products IId, IIf, IIg, and IIh were active as antimalarial drugs.
The effect of short‐chain branch structure on the properties of low‐density polyethylene
Authors: Mortimer George A.
Published: April 2003

In order to determine the effect of the molecular structure of short side branches in lowdensity polyethylene upon the physical properties of the resin, a study was carried out in which small amounts of various comonomers were added to an otherwise relatively unbranched polymer. It was found that linear short side branches have about the same effect in decreasing stiffness and increasing toughness as the natural short‐chain branches of polyethylene have. However, branches containing a tert‐butyl group increased resin toughness more than linear branches while decreasing stiffness by about the same amount. Thus, by adding a small amount of branched, short side branches, it is possible to obtain an optimum balance of physical properties not obtainable from low‐density ethylene homopolymer.
Infrared studies of cryogenic transitions in poly(ethylene terephthalate) and polystyrene
Authors: Huang Y. S. , Koenig J. L.
Published: April 2003

Infrared absorbance measurements as a function of temperature down to 13°K have been made on poly(ethylene terephthalate) and polystyrene. Transition temperatures are assigned to the temperatures where there are abrupt changes in the absorbance or integrated band intensities. Bands of known structural origin arising from either crystal‐line or amorphous phases are studied to probe the structure basis and environment effect for each transition. Transitions are found around 50, 120, 180, and 220°K for PET and around 50° and 235°K for polystyrene.
Composite membranes for seawater desalination by reverse osmosis
Authors: Riley R. L. , Lonsdale H. K. , Lyons C. R.
Published: April 2003

A composite reverse‐osmosis membrane has been developed for seawater desalination having a 400‐Å semipermeable barrier. The membrane is prepared by directly forming a very thin film of a polymer, generally cellulose triacetate, upon the finely porous surface of a supporting membrane. The composite membrane, capable of desalinating seawater in a single pass, has demonstrated improved flux stability at high pressures over modified membranes currently used to desalinate brackish water.
The application of thermogravimetric analysis to an electrophoretically deposited polymer coating
Authors: Levine Solomon L. , Bell Harry F.
Published: April 2003

An electrophoretically deposited poly(vinylidene chloride)–poly(vinyl chloride) and epoxy ester coating has been shown to provide adequate protection for Be‐Cu from hostile environments. The data presented show that thermogravimetric analysis can be readily applied for drying analysis and quality control of the polymer ratio.
Thin water vapor barriers for paper
Authors: Liepins R. , Kearney J.
Published: April 2003

Low‐pressure plasma technique was used in the deposition of thin polymeric coatings upon a filter paper. Sixteen different monomers, including aromatic and aliphatic hydrocarbons, nitriles, chlorine‐containing compounds, and a silane, were used in the coatings. Most of the coatings functioned as water vapor barriers in different degrees, and the coated samples possessed wet tensile strengths anywhere from 3 to 34 times that of the untreated samples. Attenuated total reflectance infrared spectroscopy was used to study the chemical structure of the coatings.
Cure behavior of some resin–glass cloth systems
Authors: Jenkins Robert K. , Lister James
Published: April 2003

Changes in the dynamic modulus E′dyn of some phenolic glass cloth systems were studied as a function of cure temperatures and formaldehyde factors. The modulus changes were followed by continuously monitoring in situ the fundamental frequency of vibration of resin‐impregnated glass cloth systems bonded to metallic cantilever reeds. The apparent activation energy of crosslinking was a direct function of the formaldehyde content in the resin synthesis, ranging from 9 kcal/mole for a 1.2 formaldehyde factor phenolic, to 20 kcal/mole for a 1.8 factor. Two cure parameters at 50% and 100% apparent mechanical conversion were established.
Studies on sulfur vulcanization of natural rubber accelerated with diphenylguanidine both in presence and absence of dicumyl peroxide
Authors: Manik S. P. , Banerjee S.
Published: April 2003

Diphenylguanidine acceleration of sulfuration of natural rubber both in the presence and absence of dicumyl peroxide (DCP) has been studied. DPG enhances the rate of decomposition of DCP, and the crosslinking maxima due to DCP are lowered by DPG to some extent, which increases with the concentration up to a limiting value. The rate of sulfur decrease is very high and is dependent on DPG concentration but practically independent of the presence of ZnO and stearic acid. It is observed that with constant level of DCP and sulfur, crosslinking increases with the increase of DPG concentration and finally becomes additive when the molar proportion of DPG: S8 approximately equals 1:1. In presence of ZnO and stearic acid, with each increment of DCP concentration crosslinking is retarded for both systems. Mechanisms have been suggested in terms of polar and radical process.
Surface morphology of polyethylene after treatment in a corona discharge
Authors: Kim C. Y. , Goring D. A. I.
Published: April 2003

Corona treatment of low‐density polyethylene in oxygen or oxygen‐containing gases produced bumps on the surface, while treatment in nitrogen, hydrogen, argon, or helium caused no detectable surface change. Bumps made by an oxygen corona increased in size with time and temperature of the treatment. The bumps were removed when a treated polymer sheet was dipped into solvents such as CCl4, ethanol, or 0.2% aqueous NaOH. Infrared analysis indicated that most of the oxidized layer was eliminated from the polymer surface by solvent dipping and that the degraded products contained a substantial proportion of CH2 groups. It is suggested that the bumps are caused by the migration of low molecular weight degradation products to charged areas of the polymer surface.
Corona‐induced autohesion of polyethylene
Authors: Kim C. Y. , Evans J. , Goring D. A. I.
Published: April 2003

If a low‐density polyethylene sheet is treated in a corona discharge and subsequently pressed to a similarly treated sheet at 45°C, the bond formed is much stronger than that between similarly pressed but untreated sheets. Several series of observations have indicated that this enhanced autohesion is not due to surface oxidation or to surface crosslinking (CASING). Evidence is presented that the effect may be related to some type of electret formation induced in the polymer sheet by the corona discharge.
Mechanical properties of alternating copolymers of acrylonitrile and butadiene
Authors: Furukawa J. , Nishioka A.
Published: April 2003

The alternating copolymer was prepared from butadiene (BD) and acrylonitrile (AN) with ethylaluminum dichloride as a complexing agent and with vanadyl chloride as a catalyst, and was investigated to explain effects of composition and sequence distribution on the physical properties, especially the viscoelastic properties and the ultimate mechanical properties. In the unvulcanized state, the viscoelastic properties of the alternating rubber is not essentially different from the random one, except for a slight difference in the relaxation spectra. However, the vulcanized rubbers show different shift factors. The latter depends upon the glass transition temperature (Tg.) Since the alternating copolymer possesses a Tg lower than the random one, the nature of the alternating copolymer corresponds to that of the random copolymer having an AN content of 40%. The difference in dynamic properties can be expressed with the different shift factors. In the isofree‐volume state or at the temperature Tg + 25°C, the rubbers having various acrylonitrile contents and various degrees of alternation exhibit almost the same dynamic properties. However, the strain at break of the alternating rubber is higher than that of the random one. The temperature of maximum strain increases with increasing degree of alternation. The alternating rubber shows higher stress at break than the random one. The stiffness of the chain of the alternating copolymer is smaller than the random copolymer; in other words, the molecular chain of the former is more flexible than the latter. It can be said that the alternating copolymer is an excellent rubber having high tensile strength and elongation at break.
Electron‐microscopic investigation of cerium–cotton cellulose reactions
Authors: Muller Linda L. , Hebert Jacques J. , Rollins Mary L.
Published: April 2003

Cotton fibers were treated with an aqueous solution of ceric ammonium nitrate and examined with the electron microscope. The greatest deposition of cerium occurred in the primary wall due largely to the reaction with noncellulosic constituents in this area of the fiber. The use of ceric ions for an electron‐microscopic stain was found ineffective for producing the desired contrast in the cotton fiber.
An improved dilatometer for polymers based on beta‐particle absorption
Authors: Martin‐Löf S. , Söremark Ch.
Published: April 2003

The theoretical background and the operation of a new dilatometric technique based on the absorption of beta particles is described. The thermal expansion of the samples is determined by their change in weight per unit area with change in temperature. The experimental accuracy in a determination of a relative change in weight per unit area is, at a counting time of 103 sec, approximately 4 × 10−5, which is close to the theoretical value. The applicability of the new device is illustrated by six runs on five different samples, among which hygroscopic and porous samples are represented. The temperature range covered is −60° to +70°C.
Dispersion in gel permeation chromatography. A rapid numerical solution to Tung's integral equation
Authors: Smit J. A. M. , Hoogervorst C. J. P. , Staverman A. J.
Published: April 2003

A rapid iteration method has been developed to correct the molecular weight averages calculated from raw GPC data for dispersion. Though simple in its performance, it covers the general case that the instrumental spreading characteristics (Tung's resolution factor h) depend on the elution volume. Moreover, it is irrelevant whether the calibration curve, being the logarithmic plot of the molecular weight versus the elution volume, is linear or not. The method has been applied to a number of well‐characterized polystyrene mixtures and yields molecular weight averages which agree with those predicted theoretically. The effect of asymmetry exerted by the dispersion on both molecular weight averages M̄n and M̄w is also discussed.
The flow of very dilute polyox solutions into a region of sudden capillary tube enlargement
Authors: Little R. C. , Wiegard M.
Published: April 2003

The flow of dilute drag reducing polymer solutions through capillary tubes into a region of slightly greater tube diameter is characterized by almost complete recovery of the fluid. It is conjectured that the polymer molecules react to prevent the loss of kinetic energy by minimizing the formation of eddies resulting from the expansion.
Organometallic polymers. II. Crosslinking of ferrocenylene–methylene‐type polymers
Authors: Gal Alon , Cais Michael , Kohn David H.
Published: April 2003

Poly(ferrocenylene‐methylmethylene) (PFMM) was prepared and subsequently crosslinked by the aid of either 1,1'‐bis(α‐hydroxyethyl)ferrocene or polyfunctional ferrocene polymers, containing reactive‐CH2OH or‐CH(CH3)OH groups. The thermal behavior of both the primary polymer and the thermoset was investigated. The solubility parameter of PFMM was determined and the degree of crosslinking was studied by solvent swelling and sol fraction measurements. Various thermosetting structural composites were prepared and subjected to mechanical testing.
Failure criteria for polymeric solids
Authors: Nicolais L. , Dibenedetto A. T.
Published: April 2003

A theory for predicting the stress–strain characteristics of polymeric solids is developed in terms of a description of microdefect formation. The process of irreversible change in these solids is assumed to be a combination of nucleation of submicroscopic defects at stress inhomogeneities and their subsequent growth to macroscopic dimensions. Straining results in the generation of crazes and cracks which can lead to catastrophic failure through either a general yielding of the material or by brittle fracture. It is assumed that nucleation of submicroscopic defects is an activated process and that defect growth is one‐dimensional and linear. The total strain is expressed as the sum of an elastic recoverable strain and a nonlinear, nonrecoverable strain, and expressions are obtained for the stress as a function of time, temperature, and loading history. The criterion for yielding is defined in terms of a gross volume change associated with cavitation within crazes. The sum of the normal Poisson expansion plus this additional volume change leads to a deflection of the stress–strain curve. The criterion for brittle failure is defined in terms of a critical defect size. If the defects grow to their critical size before the stress–strain curve reaches a maximum, brittle failure occurs. The parameters of the resulting model are calculated for polyphenylene oxide polymer based on constant rate of loading experiments, and then the general creep behavior, including the time required under constant load for cold flow, is predicted. Experimental data are shown to agree with these predictions.
On the single‐point determination of intrinsic viscosity
Authors: Varma T. D. , Sengupta M.
Published: April 2003

In the present paper we have analytically derived a single‐point equation for determining the intrinsic viscosity of a polymer. It is observed that the proposed equation gives a much better agreement with the extrapolated value of [η] over a wide range of concentration for good as well as poor polymer–solvent systems.
Solution of Tung's axial dispersion equation by numerical techniques
Authors: Ishige T. , Lee S.‐I. , Hamielec A. E.
Published: April 2003

Numerical methods for the solution of Tung's axial dispersion equation have been developed and comprehensively evaluated. These methods are general and can be applied where the instrumental spreading function is unsymmetrical and nonuniform. Computation times required are comparable to those of the method of Chang and Huang being about 10 sec per case on the CDC6400 computer. Memory requirements are minimal and this should permit their use with minicomputers for data acquisition and processing.
The instrument spreading correction in GPC. III. The general shape function using singular value decomposition with a nonlinear calibration curve
Authors: Rosen Edward M. , Provder Theodore
Published: April 2003

The Gram‐Charlier series was suggested as an empirical instrument spreading function in the first paper (part I) of this series. In the second paper (part II) of this series, the Fourier transform method was used together with the suggested series to solve Tung's integral equation. In this paper, an alternate method for solving Tung's equation is proposed which eliminates some of the limitations of the Fourier transform method. In the approach used in this study, Tung's integral equation is approximated by a set of linear equations. Since no unique least‐squares solution can be computed, a closely related problem whose solution closely approximates the original problem is formulated and solved using singular value decomposition. By avoiding the use of the smallest singular values and forcing the equality of the areas of the corrected and the uncorrected chromatograms, an approximate solution to the original problem is obtained in which the oscillations inherently present due to the ill‐posed nature of the problem are filtered out. The performance of the method with the experimental data given in Part II is indicated.
A moderately high shear viscometer for measuring low specific viscosities
Authors: Chan F. S.
Published: April 2003

A simple, moderately high shear capillary viscometer which can be used up to a shear rate of 150,0000 sec−1 is described. The use of a twin viscometer arrangement has eliminated the need of elaborate pressure control and adjustment units. Experimental results obtained by use of the viscometer to measure the specific viscosities of a charged colloid at two different shear rates are presented.