bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and properties of a neophyl type anion exchange resin
Authors: Hatch Melvin J. , Lloyd Winston D.
Published: April 2003

The common strongly basic Type I anion exchange resins,
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contain benzylictrimethylammonium groups. In OH− form, the resins are unstable above 60°C. due to nucleophilic attack by OH− on the benzylic and methyl carbon atoms. Reactivity of benzylic carbon sites relative to methyl sites is about 4 to 1. More stable resins would be desirable, so laboratory synthesis and stability study was made of a resin which contained neither benzylic carbon atoms nor β‐carbon atoms having hydrogen atoms which could give elimination reactions. This resin,
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containing neophyltrimethylammonium groups, nevertheless lost strong base capacity more readily than a comparative resin containing benzylic trimethylammonium groups. The breakdown was primarily at the methyl carbon atoms, however, so almost all weak base capacity was retained. The greater reactivity of methyl groups on the neophyl resin—relative to methyl groups on benzylic resin—can be due to internal compressional strain between the methyl groups of the nitrogen and the methyl groups of the β‐carbons.
Kinetic studies on the vulcanization reaction accelerated with 2‐mercaptobenzothiazole
Authors: Chatterjee Pronoy K. , Sircar Anil K.
Published: April 2003

Kinetic data for vulcanization of rubber with sulfur, accelerated with 2‐mercaptobenzothiazole (MBT) are presented. The decrease in concentration of sulfur and MBT during vulcanization under various conditions of temperatures have been determined with a precise amperometric method developed by the authors. The order of reaction for disapperance of sulfur was found to be unity. The energy of activation and frequency factor were 28.8 kcal./mole and 4.0 × 1013, respectively. The kinetics of disapperance of MBT was also first‐order, and the rate of reaction, energy of activation, as well as frequency factor were much lower than those for the disapperance of sulfur. The consumption of sulfur proceeded as long as any free sulfur was present in the sample, indicating that the consumption of MBT is closely tied up with the disapperance of sulfur. It was found that about 133 atoms of sulfur were consumed for the disappearance of one molecule of MBT. The mechanism of ring opening involving an attack by the accelerator radical as proposed by Gordon is supported by the present investigation.
Linear expansion measurements of polymers by means of a capacitance technique
Authors: Maurer John J. , Tsien H. C.
Published: April 2003

The design, construction, and operation of a unit for measuring linear expansion properties of polymers is described. This unit utilizes a proximity transducer capacitance gauge to measure variations in capacitance caused by expansion of a sample of polymer held in an Invar (low expansion alloy) sample holder. Measurement of displacement and of temperature is continuously recorded on an X–Y recorder. The effect of operating conditions on the measurement of the linear expansion is described, and certain experimental artifacts are shown. In addition, the application of the instrument to polypropylene, styrene–butadiene rubber, butyl rubber, and to ethylenepropylene rubber is described. Distinct, nonliner regions were found, above the normal glass transition temperatures, for butyl rubber and for ethylene–propylene rubber. In the former case, the effect is probably due to crystallinity; in the latter case, there are probably two minor transitions at about −35°C. and at about −5°C. in addition to the major transition at −67°C. These minor transitions may be due to atactic and to stereoblock propylene segments, respectively.
Phenylene‐perfluoralkylene silicones
Authors: Fuqua Samuel A. , Silverstein Robert M.
Published: April 2003

This paper described the preparation and properties of a new class of silicone polymers, the phenylene‐perfluoroalkylene silicones. A direct measure of ratios of copolymer units in silicone copolymers was developed during this work.
Plasticization of methylolacrylamide copolymers by grafting onto a styrene–butadiene backbone
Authors: Melrose G. J. H. , Solomon D. H.
Published: April 2003

The development of a methylolacrylamide–styrene copolymer into a product suitable for use as a general‐purpose industrial or appliance enamel has been described; the choice of a suitable means of plasticization is emphasized. The incorporation of ethyl acrylate in the copolymer is expensive and was found relatively inefficient. Plasticization by blending the copolymer with tricresyl phosphate, butyl cyclohexyl phthalate, or dioctyl phthalate gave excessive thermoplasticity. Attempted plasticization by blending the copolymer with conformationally different macromolecules failed owing to incompatibility; this was overcome by reacting the macromolecules with the acrylic copolymer instead of blending: First, a butyl alcohol modified methylolacrylamide–styrene copolymer was transetherified with cetyl alcohol and in a second synthesis, transetherified with coconut oil monoglyceride. Third, an acrylamide–styrene–acrylic acid copolymer was esterified by the same monoglyceride, methylolated, and then butylated. Finally, an acrylamide–styrene copolymer was copolymerized and grafted onto a styrene–butadiene copolymer. This latter type of plasticization, which should be a general and valuable method, was supplemented by plasticization from dioctyl phthalate and yielded, after heating, economical and durable films with good mechanical properties.
Polymerizations of nitroalkyl acrylates
Authors: Tanaka Atsushi , Sasaki Kenichi , Hozumi Yukio , Hashimoto Osamu
Published: April 2003

We have prepared some nitroalkyl acrylates and methacrylates by a method involving alcoholysis, and investigated their polymerizability. 2‐Nitrobutyl acrylate (NBA) was extensively studied. The especially purified NBA monomer has good polymerizability without inhibiting radical polymerization and gives a thermally stable polymer. From copolymerization experiments with styrene, methyl methacrylate, and acrylonitrile, the Q and e values of NBA were estimated to be 0.47 and 0.85, respectively. The copolymerization behavior of NBA with some polyglycol dimethacrylates and unsaturated polyesters are comparable to those of n‐butyl acrylate. This monomer has little tendency to polymerize with organometallic initiators, but some polymers obtained are found to be crystalline. The polar and steric effects of the nitro group situated on the ester side chain are discussed.
Anionic graft polymerization of vinyl monomers on cellulose and polyvinyl alcohol
Authors: Feit Ben‐Ami , Bar‐Nun Akiva , Lahav Meyer , Zilkha Albert
Published: April 2003

Graft polymers of acrylonitrile, methacrylonitrile and methyl methacrylate on polyhydroxy polymers such as cellulose and polyvinyl alcohol were prepared by anionic graft polymerization. The alkali alkoxide derivative of the polyhydroxy polymer backbone was used as initiator of polymerization. The graft polymerizations were carried out in liquid ammonia and other inert solvents at low temperature. Grafting was accompanied by considerable homopolymerization caused by chain transfer to monomer and to ammonia. The graft polymers were separated from homopolymers and unreacted polyhydroxy polymers by extraction with suitable solvents. The per cent of the grafted vinyl polymer increased with increase in the monomer and alkoxide concentration. No crosslinking occurred during the anionic graft polymerization, and soluble graft polymers were obtained.
Structural characterization of vulcanizates. Part IV. Use of triphenylphosphine and sodium di‐n‐butyl phosphite to determine the structures of sulfur linkages in natural rubber, cis‐1,4‐polyisoprene, and ethylene–propylene rubber vulcanizate networks
Authors: Moore C. G. , Trego B. R.
Published: April 2003

Determinations of the degree of chemical crosslinking and crosslinking efficiency values E (i.e., the number of sulfur atoms combined in the network per chemical crosslink present) have been used in conjunction with the chemical probes triphenylphosphine and sodium di‐n‐butyl phosphite to establish the structural features of sulfur links in vulcanizate networks derived from a variety of accelerated natural rubber–sulfur systems, from a cis‐1,4‐polyisoprene–TMTD–zinc oxide system, and from natural rubber and ethylene–propylene rubber crosslinked with a dicumyl peroxide–sulfur system. The triphenylphosphine converts polysulfide links into monosulfide and, to a lesser extent, disulfide links. The values of E′, i.e., the number of sulfur atoms combined in the network per chemical crosslink present after triphenylphosphine treatment are, therefore, a measure of the extent of main‐chain modification in the network by cyclic monosulfide groups and/or pendant groups of the type: SxAccel. (where x ≥ 1 and Accel. is an accelerator fragment). Sodium di‐n‐butyl phosphite cleaves di‐ and polysulfide crosslinks but leaves monosulfide and carbon–carbon crosslinks intact, and thus determination of the degree of chemical crosslinking before and after treatment with this reagent yields estimates of these two different classes of crosslinks. The combined results indicate that the efficiency of utilizing sulfur for crosslinking and, therefore, the structural complexity of the derived networks are very sensitive to the nature of the vulcanizing system (type and relative concentrations of crosslinking agent, accelerator, and activator) and vulcanizing conditions (time and temperature of cure). In general, the proportion of crosslinks which are di‐ and/or polysulfidic decreases with increasing cure time, and for the accelerated sulfur systems the structural complexity of the network increases with cure time, especially at higher vulcanizing temperatures and with low concentrations of fatty acid activator.
Wet oxidation of undrawn nylon 66 and model amides
Authors: Mikolajewski E. , Swallow J. E. , Webb M. W.
Published: April 2003

Undrawn nylon was found to be susceptible within a few days to degradation in wet or humid conditions at temperatures between 50 and 90°C. Model N‐substituted amides, although not affected by these conditions, were attacked by hydrogen peroxide solutions. The degradation proceeded principally by rupture of the bond between the nitrogen of the amide and the carbon of its α‐methylene group, consequent upon oxidation at this carbon. Unsubstituted primary amide, carboxyl, and aldehyde endgroups were formed, together with ammonia by hydrolysis of the oxidized amide. The bond between the α and β carbons of an N‐methylene chain also suffered breakage, giving formic acid and carbon dioxide. The former could also arise by rupture of any initially produced N‐formyl or N‐formoyl amides. The appearance of lactic acid from butylacetamide showed that oxidation could proceed along the N‐alkyl chain. Fragments of suitable size broken from the main chain of nylon became water‐soluble and relatively stable to further attack by air or oxygen. These pieces essentially retained the nylon structure, but possessed two carboxylic ends and an average molecular weight of less than 600. A maximum oxygen uptake of about 30 moles per mole of original amide was calculated, corresponding to complete conversion into these soluble fragments. Significant degradation did not occur for many months at 60°C. in dry conditions or in solutions of 8‐hydroxyquinoline, a process which has been patented. The latter was considered to function by chelating heavy metals into an inactive form and inhibiting peroxide formation.
Solution of gases in oriented poly(ethylene terephthalate)
Authors: Vieth W. R. , Alcalay H. H. , Frabetti A. J.
Published: April 2003

The solubilities of nitrogen, oxygen, argon, methane, and carbon dioxide in thin films of crystalline oriented poly(ethylene terephthalate) in the glassy state were studied by the static sorption method. High pressure sorption isotherms were obtained for carbon dioxide. Results indicate that, above a certain film thickness, solubilities of all gasses in the crystalline oriented polymer (Mylar) are virtually identical to those in the unoriented crystalline polymer. Solubility constants are correlated with gas force constants, ϵ□k, and the heats of sorption obtained for methane and carbon dioxide are nearly the same for both the oriented and unoriented films. The sorption isotherms obtained for carbon dioxide are nonlinear but may be well described by considering dual sorption modes. One of these, ordinary dissolution, is described by Henry's law, while the other, “hole filling,” is characterized by a Langmuir expression. Solubilities of carbon dioxide in the thinnest oriented films (1 mil) are markedly higher than in the unoriented film. Analysis of the sorption data indicates that both the hole saturation constant, and the hole affinity constant, are larger in the 1‐mil oriented film. The amorphous phase appears to be different also, exhibiting a larger capacity for dissolved gas. Different thermal history, relating to the manufacture of the film, is advanced as a possible explanation for increased solubility.
Polymerization activity test for vinyl chloride
Authors: Georgieff K. K.
Published: April 2003

A polymerization activity test has been developed for evaluating the purity of commercial vinyl chloride. A 40‐g. portion of vinyl chloride is heated with 0.500 g. of benzoyl peroxide for 2 hr. at 70°C. in a glass liner in a stainless steel autoclave, and the weight of the polymer formed determined. The effects of the heat transfer medium in the autoclave, time, oxygen, limited agitation, catalyst concentration, and temperature on the percentage conversion of monomer to polymer were determined. The effect of acetaldehyde, crotonaldehyde, chloroprene, 1,1‐dichloroethane, trans‐1,2‐dichloroethylene, paraldehyde, and 1,1,2‐trichloroethane on the conversion and the molecular weight of the polymer are described.
Crystallization and melting of copolymers of polyoxymethylene
Authors: Inoue Masakazu
Published: April 2003

Copolymers of polyoxymethylene were prepared from trioxane in the presence of comonomers such as dioxolane, 1,3‐dioxane, dioxepane and epichlorohydrin, boron trifluoride etherate being used as catalyst. Fusion and crystallization phenomena were studied on these copolymers by use of density measurement, differential thermal analysis, dilatometry, and microscopy. The spherulite growth rate and the induction periode of the crystallization were determined. The temperature dependence of the growth rate was calculated assuming a two‐dimensional surface nucleation mechanism.
Thiol group formation in the vulcanization of natural rubber
Authors: Chakravarty Shomnath , Banerjee D. , Sircar Anil K.
Published: April 2003

The determination of thiol groups formed during vulcanization in the complete range of 3–35 parts sulfur per hundred rubber–sulfur stock is reported. The results are explained on the basis of Fisher's mechanism for vulcanization of rubber and the assumption of three stages in the vulcanization process depending on the sulfur concentration.
Fiber melt extrusion: Deviations from steady‐state behavior in the spin line
Authors: Freeman Howard I. , Coplan Myron J.
Published: April 2003

The occurrence of nonsteady‐state conditions in the melt extrusion of fibers is described. Data obtained from cinephotographs are presented which indicate that the spin line diameter at a fixed point in space can have wide fluctuations dependent upon spinning parameters. It is postulated that the interaction of an elastic bulge and variable spin line tension due to a melt inhomogeneity may be responsible for the effect. Some evidence for melt inhomogeneity is presented to demonstrate the existence of domains having flow properties different from the main mass of polymer melt.
Molecular weight distribution of a polyester
Authors: Hansen Charles M. , Sather Glenn A.
Published: April 2003

Combined solvent composition and column temperature gradients were employed to effect the efficient fractionation of a polyester into several molecular weight fractions in about 16 hr. Mixtures of methyl ethyl ketone and cyclohexane were used as eluents for the fractionation which was conducted in a copper column packed with glass beads. In previously reported polymer fractionations with solvent and temperature gradients the temperatures at all points in the column have been either above or below the melting point of the polymer. This study demonstrates that hexanediol–succinic acid polyester may be efficiently fractionated by using a column temperature range which brackets the melting point of the polymer.
Some observations on the melting behavior of textile fibers. Part II. X‐ray examination of hot‐stretched nylon 66
Authors: Warwicker J. O.
Published: April 2003

X‐ray diagrams of different samples of nylon passed over a hot‐plate held at different temperatures show that the observed effect depends on the type of nylon used. Clear evidence consistent with the melting of the core of the nylon is obtained for monofilament.
Solvent power of solvents for poly(vinyl chloride)
Authors: Moore W. R. , Hutchinson R. J.
Published: April 2003

Osmotic, viscometric, and initial phase separation studies of dilute solutions of poly‐(vinyl chloride) in cyclohexanone, cyclopentanone, tetrahydrofuran, morpholine, nitrobenzene, and tetrahydropyran are reported together with some swelling measurements involving these solvents and dioxane, acetone, and methanol. Values of the polymer–solvent interaction parameter χ1 obtained from osmotic and swelling measurements suggest the order of solvent power for poly(vinyl chloride) to be cyclohexanone > cyclopentanone > tetrahydrofuran > morpholine > nitrobenzene > tetrahydropyran. A similar order is suggested by the volumes of hexane required to cause initial phase separation. Values of intrinsic viscosity and of the viscosity slope constant k′ give somewhat different orders of solvent power. Reasons for differences in order are considered. The correlation of the volume of hexane required to cause initial phase separation with χ1 is discussed and it is suggested that the polymer is solvated in solution. Other factors affecting the solvent power of solvents for poly(vinyl chloride) would appear to include the bulk and the solubility parameter of the solvent.
Ethylene–propylene copolymers: Crystallinity, infrared, and creep studies
Authors: Linnig Frederic J. , Parks Edwin J. , Wood Lawrence A.
Published: April 2003

Density, infrared, and creep studies have been made of ethylene–propylene copolymers containing up to about 50 mole‐% propylene and their homopolymers. The degree of crystallinity (volume fraction of polyethylene crystals), as measured by density and x‐ray studies, decreases with increased propylene content. This change is also reflected in the intensity of the 13.7 μ band in the infrared spectra of the polymers. The measured amount of unsaturation (0.1–0.2%) in the copolymers is too small to account for the presence of several infrared bands which are often attributed to unsaturation. An unsaturation of 0.90% was obtained for a terpolymer where the third component was unsaturated. Indentation–creep studies showed the creep to be nearly proportional to the logarithm of time with a slope of 10% creep per decade for 0.1–10 min. Compliance–temperature graphs were found to be quite similar to those for the styrene–butadiene rubber SBR 1500.
Gas permeability of highly oriented dibutyl maleate–ethylene copolymer films
Authors: Michaels A. S. , Vieth W. R. , Bixler H. J.
Published: April 2003

The effects of extreme uniaxial orientation on gas permeation through dibutyl maleate–thylene copolymer films have been examined. Gases employed were helium, argon, and methane. Permeability constants were measured as functions of temperature between 25 and 55°C., in unstretched film and in films stretched to elongations of 490, 512, 540, and 608% (breaking point). Uniaxial cold drawing of dibutyl maleate–ethylene copolymer films into the stable necking region (elongation ca. 490%) causes only a small (30%) decrease in permeability and virtually no change in apparent activation energy of permeation; when the necked films are further stretched to elongations approaching the breaking point (ca. 600%), a significant decrease in permeability and increase in activation energy is observed. It is deduced that the major changes in crystalline texture and arrangement which this polymer undergoes in the necking process have only a minor effect upon total level of crystallinity, amorphous‐phase properties, and diffusional impedance offered by the crystallites, suggesting that changes in crystallite orientation, perfection, and shape throughout the drawing process are compensatory. When necked polymer is further stretched, however, severe restraints are imposed upon the mobility of oriented chain segments in the amorphous regions, which are primarily responsible for the observed large changes in permeabilities and permeation activation energies.
Sedimentation analysis of styrene–butadiene copolymer rubber
Authors: Homma Terutake , Kawahara Kazuo , Fujita Hiroshi
Published: April 2003

Methyl n‐propyl ketone (MNPK) at 21°C. and methyl isobutyl ketone (MIBK) at 46°C. are found to be theta conditions for a styrene–butadiene copolymer rubber commercially designated as SBR‐1500. Data for specific refractive index increment and density indicate that these solvents are appropriate for ultracentrifugation of this polymer by the method of schlieren optics. Sedimentation measurements are made on one whole polymer and six fractions in MNPK at 21°C. It is demonstrated that in this theta solvent the distribution of sedimentation coefficient s (at the limit of zero concentration) of a given SBR‐1500 can be determined, with a good accuracy, from a single sedimentation run at one nonzero concentration below 0.4 g./dl. A relation between s and molecular weight M necessary to convert this distribution of s to the distribution of M is derived by making use of the theory of Flory which correlates s limiting viscosity number, and M. It is believed that the theta conditions and the procedure of analysis presented in this paper are readily utilized for heterogeneity studies on this particular type of synthetic rubber SBR‐1500.
Thermal degradation of resins
Authors: Learmonth G. S. , Wilson T.
Published: April 2003

Differential thermal analysis and thermogravimetric analysis techniques were investigated with a view to predication of the thermal behavior and flammability of plastics materials. Paper‐reinforced phenolic and epoxide resins were used. It was found that with phenolic laminates the pattern of the thermograms was characteristic of the paper, while with epoxide laminates (and melamine) it was characteristic of the resin used. This cannot be correlated with fireproofness or flammability, and further work is necessary to establish better techniques and to study the thermal behavior of the laminates by service testing.
Network degradation accompanying the vulcanization of natural rubber with a sulfur–diphenylguanidine system
Authors: Scott Kenneth W. , Lorenz Otto , Parks Carl R.
Published: April 2003

Sol fraction and swelling values have been determined for a series of natural rubber–sulfur–diphenylguanidine vulcanizates. These data have been analyzed in terms of the Charlesby and Pinner gel network formation theory with a view to estimating the amount of permanent molecular chain scission accompanying the vulcanization. It is concluded that negligible chain scission occurs before the point of modulus reversion of these curves. In the region of cure reversion, permanent molecular chain scission does occur to a small extent. The principal factor responsible for cure reversion in this vulcanizate is crosslink scission. Chain scission is responsible for only about 3–8% of the observed cure reversion.
Chemistry of radiation crosslinking of branched fluorocarbon resins
Authors: Lovejoy E. R. , Bro M. I. , Bowers G. H.
Published: April 2003

A number of commercial and experimental fluoropolymers were subjected to ionizing radiation at elevated temperatures and the changes in melt viscosity were measured as an indication of the degree of crosslinking or degradation which occurred. Polytetrafluoroethylene, polychlorotrifluoroethylene, polyhexafluoropropylene, and a copolymer of hexafluoropropylene with perfluoroheptene‐1 decrease in melt viscosity when irradiated at 200–250°C., while copolymers of tetrafluoroethylene with hexafluoropropylene, octafluorobutylene, or perfluoroheptene‐1 increase in melt viscosity, indicating crosslinking. The results suggest that the reaction of species of the type · (where × is F or CF3) with is the important one leading to crosslinking.
Poly(oxatetramethylene) glycol. I. Influence of water on polymerization catalysis
Authors: Johnston Peter R.
Published: April 2003

Tetrahydrofuran (THF) was polymerized with cocatalysts of ethylene oxide (EO) and BF3, using THF as the solvent. The yield of polymer, based on the amount of catalyst, was very low. With water present (0.5 mole per mole of BF3 and EO) the yield increased fourfold. Polymerization was stopped by the addition of a large amount of water; the addition of water also provided the polymer with terminal hydroxyl groups. The polymer had a molecular weight of 1000 and was a clear, colorless, viscous liquid.
Effects of degradation on polypropylene melt rheology
Authors: Poller D. , Kotliar A. M.
Published: April 2003

The viscous flow behavior of molten polypropylene has been correlated with the viscosity‐average molecular weight under degradative and nondegradative conditions. The effects of unequal extents of degradation on molecular weight distribution are shown to be an important parameter in this correlation.
Microscopic domains in some synthetic polymers
Authors: Rochow T. G.
Published: April 2003

It was found that all pieces of poly(methyl methacrylate) have structure and anisotropy, no matter how they were made. There is no continuum, only differences of opinion about what the discontinuities represent. Judging from these and other results and pending the results of further experiments, the author is of the opinion that he has uncovered both macromolecular and micellar domains in poly(methyl methacrylate).
Calculation of number‐average and weight‐average molecular weight of poly(vinyl chloride) polymers from intrinsic viscosity measurements
Authors: McKinney Paul V.
Published: April 2003

Consistent data are available from several authors to provide equations for the calculation of number‐average and weight‐average molecular weights of commercial poly(vinyl chloride) polymers from determinations of intrinsic viscosity in cyclohexanone solution at 30°C. Reasonable approximations of the molecular weights can be calculated quickly by use of the following simple equations: M̄n = ½[η] × 105; M̄w = 0.9[η] × 105.
Polymer‐diluent interactions of some nitrocellulose‐nitrate ester systems
Authors: Brooks R. L. , Lawrence A. R.
Published: April 2003

The Flory‐Huggins interaction χ and the closely related heat of mixing parameter B were determined for several nitrocellulose‐nitrate ester systems. A micromethod which permitted the use of a simplified version of the Flory equation was successful in evaluating the effects of two series of nitrate ester diluents with nitrocellulose. A distinct difference exists between the effect of αω‐ and α,β‐substituted diluents as shown by the χ and B parameters. Generally, the terminally substituted nitrate esters appear to be the better solvents.
Grafting of chelating monomers to styrene—butadiene latexes
Authors: Gardner John B. , Harper Billy G.
Published: April 2003

It has been previously reported that vinyl esters have been grafted to natural rubber latex. We have grafted two other types of vinyl monomers to styrene‐butadiene latex. These monomers are the ammonium salts of acrylic acid and methacrylic acid, and the ammonium salts of vinyl chelating agents, such as N‐(ar‐vinylbenzyl)iminodiacetic acid. (Ionizing radiation doses of 0.5–2 Mrad are sufficient to accomplish the grafting.) These monomers, in the range of 2–6%, give very definite improvement in adhesion to metals. They also improve the rust resistance, and when pigmented with an iron oxide dispersion, improve the whitening resistance of the coating. The vinyl chelating monomers give the best improvement over the untreated latex, particularly in the resistance to whitening. The optimum amount of monomer is 4–6%. This compares very well with the theoretical amount for a monomolecular layer of monomer surrounding each latex particle.
Procedures to guide experiments directed to improvement of electrostatic atomization and deposition of organic coatings
Authors: Spiller Lester L.
Published: April 2003

Methods are described for determination of particle size D of paint atomized in an electrostatic field and for measurement of band width B and wraparound ratio W of a film pattern produced under standard conditions. A quantitative “figure of merit” F, defined as the ratio BW/D, can be correlated with qualitative aberrations of electrospray efficiency. This quantitative measure provides a more efficient guide to experiments directed toward upgrading electrospray performance of otherwise useful paints. Some examples are cited to demonstrate that incorporation of highly charged colloidal particles have significant effects on electrospray efficiency of paints containing vehicles of low conductivity.
Properties of semicrystalline polyolefins. II. Copolymers of 3‐methyl‐1‐pentene and 4‐methyl‐1‐pentene
Authors: Isaacson R. B. , Kirshenbaum I. , Klein I.
Published: April 2003

A study of the copolymerization of 3‐methyl‐1‐pentene (3‐MP) and 4‐methyl‐1‐pentene (4‐MP) showed that the poly‐4‐MP crystal lattice is capable of incorporating large quantities of 3‐MP without a sharp lowering of melting point or adverse effect on physical and mechanical properties. The reactivity ratio of the two monomers in copolymerization are r(4‐MP) = 6.2 ± 0.2 and r(3‐MP) = 0.1 ± 0.1. As a result, mixed feeds containing up to 80% 3‐MP produce copolymers composed primarily of repeating 4‐MP units, with a random insertion of 3‐MP monomer units. Calculations indicate that in a copolymer containing 37% 3‐MP, the probability of finding a sequence of 2 units of 3‐MP is only a little better than 5%. This copolymer shows a somewhat increased resistance to deformation under load than homopoly 4‐MP. Its crystalline melting point is 248°C.
Pyrolysis of plastics in a high vacuum arc image furnace. II
Authors: Friedman Henry L.
Published: April 2003

Samples of glass‐ and nylon‐reinforced CTL 91‐LD phenolic and G. E. 124 resin were pyrolyzed in an arc image furnace at high vacuum. Compositions of the various degradation gases are reported. Average molecular weights of these gases were calculated. A description of the mechanism of pyrolysis of G. E. 124 resins is presented. A critique of the method is included.
Use of thin films in ultraviolet studies of cellulose xanthate
Authors: Phifer Lyle H.
Published: April 2003

A procedure for the study of the chemistry of viscose based on ultraviolet measurements of a film of cellulose xanthate has been developed. To illustrate the range of usefulness of the technique, spectra of various compounds formed with cellulose xanthate, including metal salts, organic derivatives, and an acid form, the influence of solvation on several cellulose xanthate compounds, and formation and decomposition curve of cellulose xanthate derivatives are presented. Possible applications of the technique include a study of the acid decomposition of cellulose xanthate, the influence of additives, new derivatives, and the xanthation mechanism. It is also probable that the method can be used in the study of other systems where fast reaction mechanisms are involved and suitable absorption characteristics are present.
Reaction of formaldehyde with cellulose xanthate
Authors: Phifer Lyle H. , Ticknor Leland B.
Published: April 2003

Formaldehyde reacts reversibly with cellulose xanthate in aqueous acid to form a product having an absorption maximum at 280 mμ and an extinction coefficient of 11,600. The fraction of the original xanthate converted to the formaldehyde form is related to the formaldehyde concentration. The aqueous acid decomposition rate of the formaldehyde derivative is pseudo first‐order and is inversely proportional to the formaldehyde concentration. At high acidities the decomposition rate is independent of acid concentration, but the rate decreases with decreasing acidity in the pH range of 1–4. On the basis of the data obtained in these studies, the equilibrium constant for the formation of the formaldehyde derivative was found to be of the order of 10.4.8. The activation energy for the decomposition of the formaldehyde derivative is 18,600 cal./mole.
Mechanism for the aqueous acid decomposition of the formaldehyde derivative of cellulose xanthate
Authors: Phifer Lyle H. , Dux James P. , Ticknor Leland B. , O'shaughnessy M. Thomas
Published: April 2003

Kinetic equations for the decomposition of S‐hydroxymethyl cellulose xanthate in the presence of acid and formaldehyde are derived. The assumed mechanism involves an equilibrium between the S‐hydroxymethyl cellulose xanthate and cellulose xanthic acid and xanthate ion. Decomposition appears to proceed via interaction between the cellulose xanthate ion and hydrogen ion which form an activated complex that subsequently decomposes to cellulose and carbon disulfide. The equations derived show the proper dependence on acid and formaldehyde concentrations. An estimate of the equilibrium constant between cellulose xanthate and S‐hydroxymethyl cellulose xanthate is calculated from the rate constants.
Effect of ethylamine treatment on the dielectric properties and crystallinity of cellulose. I
Authors: Venkateswaran A. , Akker J. A. Van Den
Published: April 2003

A study of dielectric properties and crystallinity by x‐ray diffraction was made of ramie, cotton linters, bleached sulfite pulp, and cellophane. These cellulosic materials were treated with various concentrations of ethylamine in water. A linear relationship was found to exist between dielectric constant and crystallinity. The results also indicated that both dielectric constant and loss factor of ethylamine‐treated cellulose obeyed anomalous dispersion and absorption. The difference in density of untreated and treated samples was not significant for the range of crystallinity change observed by ethylamine treatment. In calculating the intrinsic dielectric constants of cellulose of different crystallinities the density of crystalline cellulose was used for the purposes of comparison.
Measurement of the smectic content in undrawn polypropylene filaments
Authors: Farrow G.
Published: April 2003

By the use of x‐ray diffraction techniques a method is proposed for the measurement of the “smectic” content (interpreted here as material of intermediate order) of undrawn polypropylene filaments. The method involves two estimates of crystallinity by x‐ray methods. One is considered to measure the amount of diffraction from the normal crystalline monoclinic lattice and the other the total amount of diffraction from crystalline, “smectic” and noncrystalline material. By separation of these various quantities the amount of “smectic” polypropylene can be deduced. It was found by this technique that the “smectic” content of quenched polypropylene samples decreased from 40°C. onward and approached zero at about 85°C.
Studies in hard rubber reaction. Part II. Effect of organic accelerators
Authors: Bhaumik M. L. , Banerjee D. , Sircar Anil K.
Published: April 2003

The method of differential thermal analysis has been applied to the study of thermal effects accompanying exothermic vulcanization reaction in hard rubber compounds accelerated with common rubber accelerators. Exothermic reaction was found to start at about 1% sulfur, in the case of CBS‐accelerated compound which increases linearly up to 32% and then decreases, probably due to predominance of a dehydrogenation reaction. 68/32 Rubber‐sulfur compounds containing increasing amounts of combined sulfur evolve decreasing quantity of heat and a plot of ΔH vs. combined sulfur of the precured compounds shows three stages of reaction. Accelerators were found not to affect the heat of reaction of the compounds to a great extent except in the special cases of those containing MBT and ZDC. The beneficial effect of certain accelerators is to be traced in the lowering of initiation temperatures and a decrease of slope values whereby the reaction becomes more regulated and spread out. Increase of concentration of accelerators (CBS and TMT) was found to have little effect.
Some unusual properties of graft copolymers and polyblends of β‐vinylnaphthalene and ethylene oxide
Authors: Cuddihy E. , Moacanin J. , Rembaum A.
Published: April 2003

It was found that poly‐β‐vinylnaphthalene and poly(ethylene oxide) (54:46% by weight) form homogeneous blends or graft copolymers when prepared under conditions which inhibit the crystallization of poly(ethylene oxide). Such preparations can be obtained from solutions in a good solvent for both components, either by precipitation procedures which lead to coacervation rather than fractionation, or by freeze‐drying. Preparations containing more than 46 wt.‐% poly(ethylene oxide) were characterized by modulus versus temperature curves exhibiting a minimum at about 60°C. This behavior was interpreted as due to microphase separation taking place with increasing temperature, a process which becomes irreversible above 120°C. A graft copolymer having the 54:46 composition was rubbery at room temperature, and in contrast to polyblends did not exhibit the poly‐β‐vinylnaphthalene glass transition at 138°C. The marked difference in behavior between polyblends and graft copolymers is due to the fact that in the latter irreversible microphase separation cannot take place. The above described properties seem to be peculiar to poly‐β‐vinylnaphthalene. Similar properties could not be reproduced in preparations of poly(ethylene oxide) with polystyrene, poly‐4‐vinylbiphenyl, or polyacenaphthylene. These preparations exhibited a behavior characteristic of mixtures of two incompatible polymers.
Effect of spinning bath liquids on the properties of acrylic fibers
Authors: Beevers R. B.
Published: April 2003

Fibers of an acrylonitrile copolymer spun from dimethylformamide solution into nonsolvent spinning baths are found to have tensile and contraction properties which correlate with the aggregating power of the bath.
Relation between stress–strain behavior and equilibrium volume swelling for peroxide vulcanizates of natural rubber and cis‐1,4‐polyisoprene
Authors: Bristow G. M.
Published: April 2003

Data are reported for the elastic behavior, as described by the parameters C1 and C2, and the equilibrium swelling in n‐decane, vr, for dicumyl peroxide vulcanizates of natural rubber and cis‐1,4‐polyisoprene. For natural rubber vulcanizates the correlation between C1 and vr can be described in terms of the original Flory‐Rehner equation with χ = 0.41. Tentative evidence is presented which favors this equation rather than the later modified form in which the term in vr1/2 is replaced by one in (vr1/2 − vr/2).
Effects of mixing variables and talc fillers on tensile and impact fatigue properties of some thermoplastic blends of poly(vinyl chloride) with acrylonitrile‐butadiene copolymer rubber
Authors: Lee C. C. , Rovatti W. , Skinner S. M. , Bobalek E. G.
Published: April 2003

An apparatus is described which measures simultaneously a relative change in vibrational damping and in transient electrical charging of a wafer specimen of plastic during the interval immediately following an impact blow. When impacting cycles are repeated regularly (at an energy less than the destructive level for nonfatigued specimen), the curves relating either electrical or mechanical responses to the number of impact blows show significant changes of slope at coincident intervals of the impact fatigue history, and either of these correlated effects can be used to indicate successive changes in microstructure which lead to the ultimate fracture endpoint of the fatigue test. These fatigue tests were used to study the effect of compositional and mixing variables on the properties of some heterophase thermoplastics. This study demonstrated that impact fatigue resistance can be poor in some plastic compositions which are rated to have superior impact resistance by tensile testing. Also, some special fillers in the correct quantity may improve fatigue resistance even though such filler loading will degrade other desirable tensile properties.
Polyacrylonitrile fiber behavior. II. Dependence on structure and environment
Authors: Rosenbaum Shlomo
Published: April 2003

The effect of comonomer, draw ratio, and annealing temperature on the glass transition temperature Tg and on a number of properties of polyacrylonitrile fibers has been examined. The coefficients of axial thermal expansion above Tg were found to be positive and unusually high. In water, they increased with increasing draw ratio and annealing temperature, but these effects could not (or hardly) be observed in decalin. The axial thermal expansion is compared with that of polyamide fibers, where the coefficient was positive on unstretched fibers but negative on drawn ones throughout the temperature range (25–150°C.) examined. Implications for the structure of polyacrylonitrile fibers and a number of peculiarities in their glass transition are discussed. Most of the results were in line with a structure based on stiff molecules twisted out of a straight conformation by intramolecular repulsive interaction between adjacent dipoles. An unexpectedly large proportion of compounds examined were found to exert a plasticizing action which could be related most readily to the dipole moments. The effect is attributed to a reduction in molecular stiffness and is compared with the solution behavior of the polymer. An increase in “yield point” with increasing molecular size of tensile testing medium provided evidence for an increase in volume during initial extension.
Polyhexaallylmelamine and related polymers
Authors: Gillham John K. , Petropoulos John C.
Published: April 2003

Thermoset polymers result when hexaallylmelamine and related monomers, such as 2,4‐bis(diallylamino)‐6‐piperidino‐s‐triazine, are polymerized with di‐tert‐butyl peroxide or 2,5‐dimethyl‐2,5‐di(tert‐butylperoxy)‐n‐hexane. Advantageous properties of the new systems when filled with glass fabric include high mechanical strength and modulus at elevated temperatures, solvent resistance, and excellent electrical properties, especially dielectric constant, dissipatio factor, and arc resistance. Although glass cloth‐reinforced laminates of the resins are stable to almost 400°C. in nitrogen, oxidatively they are much less stable. Nevertheless, these new resin systems have certain advantages in comparison with silicone resins and should be useful for structural and electrical applications in air to above 200°C.
Tensile stress relaxation behavior of a mechanical mixture of two polymer components
Authors: Horino Tzuneo , Ogawa Yasuo , Soen Toshiichi , Kawai Hiromichi
Published: April 2003

As one in a series of studies relating the rheological properties of mechanical mixtures of two polymer components to the degree of mixing, the temperature dependence of tensile stress relaxation behavior of two types of mixed systems, i.e., poly(methyl methacrylate)–poly(vinyl acetate) system and lightly crosslinked poly(methyl methacrylate–poly(vinyl acetate)) system, was investigated over a temperature range covering the glass transition temperatures of both polymer components. The time–temperature superposition procedure was carried out for comparison of several parameters, such as fractional free volume and its thermal expansion coefficient, which were determined on the basis of the free volume concept from the viscosity in relation to the William‐Landel‐Ferry equation, with those of the individual polymer components. Although the fractional free volume and its thermal expansion coefficient thus determined for the mixed systems were apparent values, the results may, at least qualitatively, deny the simple additivity of the free volumes of the two‐polymer mixed phases and suggest the existence of a sort of physical interaction between the phases, i.e., the internal pressure induced by one phase or the other due to a difference in thermal expansion coefficient between the phases.
Stress—strain behavior of rubber‐reinforced glassy polymers
Authors: Newman Seymour , Strella Stephen
Published: April 2003

The main objective of this work has been to develop some rational hypothesis for the toughness of rubber‐modified glassy polymers as defined by the energy to rupture in a tensile measurement. It is shown that the rigid phase yields and that the toughness is a result of the large energy absorption involved in the cold drawing of the matrix. The rubber phase acts principally to induce a yielding in the matrix. A triaxial stress field in the environment of the dispersed particles results in local increases in free volume which aid in the initiation of cold drawing and provides the rubber with sufficient breaking stress to prevent premature crack propagation.
Polyurethane latex
Authors: Suskind Stuart P.
Published: April 2003

A technique has been developed for preparing stable, film‐forming, polyurethane latices without the use of emulsifying agents. The reaction of an alkyl diethanolamine with a stoichiometric excess of an isocyanate terminated prepolymer yields a relatively low molecular weight urethane which is readily dispersed with 3% aqueous acetic acid. When small amounts of triethanolamine are employed as a third reactant, the selfemulsifiable urethane is branched. In either case, water diffuses into the suspended globules of the latex and chain‐extends the urethane to a linear or crosslinked high polymer via reaction with isocyanate endgroups. Upon drying, the creamy, white latices yield strong, elastic films which exhibit low swelling when immersed in water for extended periods. Cationic polyurethane latices were prepared from both polyester‐ and polyether‐based materials, and, in general, the expected structure–property relationships were obtained. A major stabilizing factor in these polyurethane latices is the positive charge on the particles arising from the tertiary amine salts. The latices were compatible with nonionic pigmenting and thickening agents, and they could be blended with a nonionic poly(vinyl acetate) emulsion.
Investigation of thermal oxidation and photooxidation of acetal plastics by infrared spectroscopy
Authors: Kelleher P. G. , Jassie L. B.
Published: April 2003

Infrared spectroscopy was used to study the thermal oxidation, accelerated and natural photooxidation of acetal homopolymer and copolymer. Chain scission is the predominant reaction, as revealed by changes observed in the hydroxyl, carbonyl, and methylene absorption regions of the infrared spectra. Photolysis accelerates the degradation of both plastics. Reaction mechanisms are presented to explain the behavior of these materials under oxidative conditions.
Effect of mounting technique on the laboratory weathering of polypropylene monofilaments
Authors: Forsman James P.
Published: April 2003

A comparative study was made of two methods of mounting yarns in the Weatherometer. In the first, in which test materials are wound continuously around separated halves of wooden hubs, the yarns tend to bunch. In the second, the sample is constrained from bunching but is free to relax or to shrink. Use of the second method of mounting significantly shortens exposure time and greatly improves the repeatability of tensile and elongation tests performed on exposed yarns.