bluuebunny/crossref_metadata_2025 huggingface dataset:
The sward number and mechanical properties of plastics
Authors: Roberts J. , Steel M. A.
Published: April 2003

A Sward rocker tester is used to obtain the Sward number for glass, mild steel, copper, poly(methyl methacrylate), polyethylene of various densities, and natural rubber. A relationship between the number and mechnical properties is investigated. It is shown that with metals and glass the number is essentially a frictional factor. With plastics and rubber it is a true hardness factor, involving dynamic Young's modulus, Poisson's ratio, and damping capacity. The aim of the investigation is to encourage the development of the Sward test as a nondestructive quality test for plastics.
Molecular structure and some related properties of polyethylene stretched in the amorphous and crystalline states
Authors: Chu Hyong‐Dong , Kitamaru Ryozo , Tsuji Waichiro
Published: April 2003

The molecular orientation of stretched polyethylene has been estimated separately for the crystalline and amorphous phases by using x‐ray and birefringence techniques. It is confirmed that if a hightly crosslinked polyethylene is highly stretched rapidly in the perfectly molten state and cooled to room temperature, a fibrous structure comprised of highly oriented crystallites and almost unoriented relaxed amorphous chains is produced. Some properties such as dynamic mechanical properties and thermodynamic property are discussed in relation to the molecular structure.
Tensile recoveries of cotton modified with and without crosslinks
Authors: Weiss Louis C. , Frick J. G. , McSherry Wilbur F. , Cannizzaro Anna M.
Published: April 2003

When effect of the substrate is nullified, resiliency can be defined as a function of strain, time, and humidity. Determination of improvement in the immediate, or rapid, tensile recovery readily delineates differences due to chemical modifications. Delayed recovery is usually less improved than immediate. Crosslinking cotton with dimethylolethyleneurea (DMEU) increases tensile strain recovery as the number of crosslinks increase, reduces dependency of recovery upon external strain, and produces maximum recovery at about 65% R.H. Noncrosslinking treatments produce limited increases in tensile strain recovery. Measurements on yarns crosslinked with DMEU and then hydrolyzed indicate that incalculably few residual links may contribute to tensile recovery. N‐Methylol‐N'‐methylethyleneurea treated cotton displays physical blocking and water swelling which aid recovery. Oleoyl chloride esterified cellulose has tensile recovery probably due to molecular entanglements. Its delayed or viscoelastic recovery is the most improved with immediate recovery being the least improved. The higher the moisture regain, the greater tensile modulus reduction under wet conditions. Crosslinking with DMEU under dry conditions lessens this reduction in modulus. Improvements in the tensile recovery of strain and energy, for all samples and with varied conditions of humidity and strain, correspond linearly with unit slope.
Crystallinity index of poly(ethylene terephthalate) by x‐ray diffractometry and differential scanning calorimetry
Authors: Wakelyn N. T. , Young P. R.
Published: April 2003

The crystallinity of a variety of poly(ethylene terephthalate) (PET) specimens, produced by thermal annealing, has been measured by three x‐ray diffractometric index methods and by an index method for differential scanning calorimetric data. The measurement procedures are termed indices since they involve various methods of ranking specimens in a relative manner between maximum and minimum crystallinity standards. Statistically different index values are determined by the various physical methods and procedures of calculation for many types of specimens. The integral index method, which utilizes x‐ray diffractometric data, corresponds in a more precise manner to the calorimetric index than to the other two x‐ray methods, for the cases in which oriented film is annealed in a vacuum oven and is subject to a continuous pumping environment. This treatment also produces a threefold increase in number‐average molecular weight of PET film. Annealing in sealed ampules, Mn constant, produces substantially the same results for all three x‐ray methods but different results for the calorimetric procedure. A relatively simple two‐point procedure yields virtually the same trend as the more complicated indicial methods.
Kinetics of the pyrolysis of cellulose in the temperature range 250–300°C.
Authors: Lipska Anne E. , Parker William J.
Published: April 2003

Samples of α‐cellulose, containing 0.11–0.14% ash, were isothermally pyrolyzed in a fluidized bath in a nitrogen environment at 250–298°C. Results were reported in terms of volatilization (based on weight‐loss measurements) and decomposition (in term of glucosan loss). The findings show three distinct stages of pyrolysis: (1) an initial period of rapid decomposition and weight loss; (2) a range in which both the volatilization and decomposition are of zero order; (3) a region in which the volatilization follows a first‐order rate, leaving a char deposit which does not undergo further pyrolysis. The degree of decomposition and volatilization occurring during the zero‐order phase increases with increasing temperature. A single activation energy of 42 kcal./mole describes both the decomposition and volatilization rates in the zero‐order phase over the entire 250–298°C. range.
Low‐temperature thermal expansivities of polyethylene, polypropylene, mixtures of polyethylene and polypropylene, and polystyrene
Authors: Zakin Jacques L. , Simha Robert , Hershey Harry C.
Published: April 2003

Length‐temperature measurements on a series of polymer blends over the whole range of composition from pure polyethylene to pure polypropylene and one set of determinations on a 50:50 copolymer and on polystyrene are evaluated. The total crystallinity of the samples did not exceed 54%. The experimental procedure utilized a linear variable differential transformer without the use of a confining fluid, and the temperature ranged from about +20 to –185°C. A least‐square numerical differentiation procedure based on moving arcs is applied to yield directly the coefficients of thermal expansion as a function of temperature. The linear voltage differential transformer (LVDT) technique can detect transitions in which the change in thermal expansion coefficients is less than 10−5°C.−1. In polypropylene as well as the blends, the principal glass transition is clearly seen in the range observed by others, namely at about –9 to –14°C. Its location varies only slightly with composition at polyethylene contents less than 88 mole‐%. For polyethylene the transition region broadens noticeably. The results are suggestive of two transitions for 0 > T > –40°C. A second transition region is observed for either pure component around –126°C. Its location varies some what with composition. However, our results do not indicate the appearance of an additional transition region characteristic of the mixture. The copolymer exhibits a major transition at –61°C. in good agreement with earlier workers. The thermal expansion decreases again around –150°C. In general our observations concerning transitions below Tg are consistent with dynamic results.
Dielectric relaxations in poly(vinyl alcohol)
Authors: Shida Ken‐Ichi , Wada Yasaku
Published: April 2003

Dielectric constant and loss of poly(vinyl alcohol) films of different stereoregularity and crystallinity are measured at frequencies from 30 cps to 3 Mcps in the temperature range from −50 to 25°C. The relaxation strength of local mode relaxation is higher for atactic and syndiotactic samples than for isotactic samples when compared at zero crystallinity. This behavior is reasonably explained in terms of interchain hydrogen bonds in the former and intrachain hydrogen bonds in the latter. Dielectric constant and loss of the crystal aggregate of atactic poly(vinyl alcohol) are measured at temperatures from −50 to 140°C. The relaxation strength of the crystalline relaxation is in good agreement with the theory in which the relaxation is attributed to torsional vibration of crystalline chains. The weak loss peak at low temperatures which almost agrees with the local mode relaxation of bulk samples in the frequency‐temperature position is ascribed to the surface disorder of single crystals.
Cure of epoxy resins with aromatic amines: High heat‐distortion studies
Authors: Illman J. C.
Published: April 2003

Castings having unexpectedly high heat‐distortion temperatures result when certain treated resins of the EPON

EPON is a registered trademark of the Shell Oil Company.

828 type and about 75% of the stoichiometric amount of m‐phenylenediamine, are postcured for 10–20 hr. at 175–200°C. The improvement in heat‐distortion temperature is about 100°C., to values as high as 250°C. A recrystallized resin has given the highest values. Other glycidyl ethers of polyphenols have shown this phenomenon to a lesser degree, but other amine curing agents, including isomers and substitution products of m‐phenylenediamine, have not. Some evidence of a new curing reaction has been developed, by NMR and pyrolysis studies of model compounds, which supports the postulate that the m‐phenylenediamine is alkylated with a fifth epoxy group during the postcure, presumably at a ring carbon, resulting in greater crosslinking.
Rheological behavior of some acrylic fibers dissolved and spun in the ZnCl2 system
Authors: Tzentis L. S.
Published: April 2003

Concentrated solutions of Acrilan 16 and 1656, Creslan 58 and 61, Orlon 42, and several experimental acrylic copolymers were prepared by dissolution of the staple fibers in 60% ZnCl2. The solutions were investigated rheologically. It was shown that a 3.5‐power relationship between the log of the Newtonian viscosity and the log of the molecular weight held for these solutions. Their elastic behavior as exhibited by the Barus effect was shown to be a function of shear stress and independent of molecular weight or composition. The ZnCl2 solutions of the acrylic fibers were spun under a harsh and a mild condition of coagulation. On physical and beinding properties of the fibers, mild coagulation has an effect similar to an increase in the content of the minor component of the copolymer. The loop properties and shrinkage of Turbo‐stretched fibers are shown to be mainly functions of their composition.
Strength of epoxy polymers. I. Effect of chemical structure and environmental conditions
Authors: Kwei T. K.
Published: April 2003

The breaking times of two crosslinked epoxy polymers under constant stresses were found to decrease at high temperature and humidity. The effect of humidity is, in terms of Bueche's theory, to increase the jump frequency of the polymer segments and to reduce the number of polymer units in cooperative motion in a jump process. When two epoxy polymers with different segment mobilities are compared at a given temperature, the stress‐breaking time relationship shifts toward longer times for the polymer with the higher transition temperature. The relation is also applicable in the presence of absorbed water molecules.
Detection of polymer transitions by measurement of thermal properties
Authors: Steere Robin C.
Published: April 2003

Thermal diffusivity, thermal conductivity, and specific heat per unit volume were measured for the following polymers: poly(ethylene terephthalate), polytetrafluoroethylene, polycarbonate, polypropylene, and three poly(vinyl chloride) samples plasticized to different levels. First‐ and second‐order transitions can be identified and located by the following features in the thermal property‐temperature curves: discontinuities, sharp inflections, broad inflections, sharp maxima, broad maxima, and change in linear slope. The results for poly(vinyl chloride) indicate the possibility of the use of plasticizer to control the thermal insulation properties of polymers, both for steady‐state and unsteady‐state conduction.
Studies with thin membranes. II. Measurement of membrane potentials and evaluation of membrane fixed charge density
Authors: Lakshminarayanaiah N.
Published: April 2003

Membranes prepared from 5% Parlodion solution have been characterized. These and other membranes prepared from 0.38, 0.5, 1.0, 2.0, and 3.0% Parlodion solutions and already characterized, have been used severally to estimate the number of anionic sites present in them by two different methods. The potentiometric method, which is indirect, gave values of X̄P which were higher than X̄T, the values obtained by a direct isotopic method. The order was reversed for well‐characterized ion‐exchange membranes. These discrepancies were attributed to the shortcomings of the Teorell, Meyer, and Sievers theory of membrane potentials from which the potentiometric method was derived.
Mechanisms of oxidative degradation. II. Effect of metallic salts and metal deactivators on the oxidation of polybutadiene
Authors: Lee Lieng‐huang , Stacy C. L. , Engel R. G.
Published: April 2003

The metal‐catalyzed oxidation of polybutadiene is further discussed. The mild catalytic effect of stearic acid on the oxidation was shown due to the synergism of the acid and a stearate. The synergism was also found for the mixture of two different stearates. The results of the preliminary study on the stabilization are given. For both iron and copper stearates, zinc diethyldithiocarbamate (ZDC) was found to be the best metal deactivator, and the chelated mixture behaved as an oxidation inhibitor. Tetramethylthiuram disulfide (TMT), phenyl‐β‐naphthylamine, and oxamide were less effective.
Prediction of mechanical behavior of plastics undergoing decomposition from the combined effects of environmental exposure and stress
Authors: Goldfein S.
Published: April 2003

A study was made to determine whether the behavior of plastics undergoing breakdown from the effects of stress, elevated temperatures, and chemical attack could be predicted by means of a mechanical‐chemical equation of state. Five systems were studied, the first four of which were tested for retention of strength at room temperature after environmental exposure: (a) glass‐reinforced polyester laminate exposed to an alkaline medium at elevated temperatures; (b) cellulose laminate exposed to elevated temperatures, resulting in oxidative degradation; (c) paper‐phenolic laminate exposed to elevated temperatures, resulting in further crosslinking followed by oxidative degradation; (d) heat‐resistant glass fiber polyester resin laminate exposed to very high degradative temperatures; and (e) same material and treatment as (d) except that the specimens were under stress during the exposure (stress rupture). It is concluded that the effects of the various environments on the mechanical properties of the plastics under study can be predicted accurately by use of a parameter of the equation of state representing a second‐order chemical reaction.
Degrees of heterogeneity of distribution of formaldehyde crosslinks in cotton cellulose
Authors: Rowland Stanley P. , Rollins Mary L. , Degruy Ines V.
Published: April 2003

The distribution of formaldehyde crosslinks in cotton cellulose has been followed by electron micrographic analyses of fiber cross‐sections and by kinetic analyses of rates of reactions of formaldehyde with cotton. Rapid and slow phases of the crosslinking reactions are indicated to extents which vary with the specific processes of reaction. A wide range in heterogeneity of distribution of crosslinks is found among the compositions investigated, the most heterogeneous distribution appearing in a high concentration of crosslinks in peripheral regions of the fiber. It is evident that additional substantial differences among the formaldehyde‐crosslinked cottons are due to different extents of reaction of agent per accessible hydroxyl group.
Swelling characteristics of gel fractions of formaldehyde‐modified cotton celluloses
Authors: Stark Samuel M. , Rowland Stanley P.
Published: April 2003

A method for assessing extent of swelling of the gel fraction of formaldehyde‐modified cottons, employing cupriethylenediamine hydroxide as the swelling agent, is described. Substantial differences in apparent specific volumes of swollen gel fractions are observed for cottons crosslinked by different processes to the same level of agent. The apparent crosslink density measured by the swelling of gel fraction increases with formaldehyde content of the cotton; at 0.20% formaldehyde the order of increasing crosslink density in the various processes of reaction is as follows: nonaqueous system (forms D and D′) < aqueous system (forms W and W′) <swelling system (form F) < vapor system (form V) < bake‐cure system (form C).
Measurement of the limiting viscosity with a rotating sphere viscometer
Authors: Hermes R. A.
Published: April 2003

The rotating sphere viscometer is found to be a superior method of measuring the viscosity at zero shear rate of moderately viscous non‐Newtonian fluids. The effects of inertia and container walls are studied experimentally. The shear stress‐shear rate relationship is found to be linear at the low shear rates studied; thus yielding the limiting viscosity. This measured value of the limiting viscosity can be used in empirical models that are applicable over a wide range.
Alkylbenzene‐Maleic anhydride photoadducts as dianhydrides for epoxies and polyimides
Authors: Bradshaw J. S. , Stevens M. P.
Published: April 2003

Dianhydrides from ethylbenzene, cumene, and branched C5‐C6 alkylbenzene‐maleic anhydride photoadducts have a surprisingly high solubility in epoxy resins. Dianhydrides from benzene, toluene, and n‐C10‐C13 alkylbenzene adducts, which are homologs of the above, were not soluble. Epoxies cured with the ethylbenzene and cumene dianhydride adducts had higher heat distortion temperatures and flexural strengths than epoxies cured with two commerical monoanhydrides. High‐melting polyimides were also obtained with these two new dianhydrides.
Mechanisms for initiating thermal degradation of certain anhydride‐cured epoxides
Authors: Fleming Gerald J.
Published: April 2003

The mechanisms initiating the unusual thermal degradation of epoxy resins cured with methylbicyclo [2.2.1] hept‐5‐ene‐2, 3‐dicarboxylic anhydride were investigated. Two mechanisms were elucidated, each assuming greater importance than the other depending upon the severity of the thermal environment. One is an internal acid‐initiated mechanism operating from 240 to 350°C. under slow heating rates. The other is a reverse Diels‐Alder reaction which operates above 350°C., usually under instantaneous pyrolysis conditions such as encountered in ablation. These two mechanisms, working simultaneously, promote further crosslinking of the resin system giving rise to a greater amount of carbonaceous residue than would otherwise be expected.
Properties of linear elastomeric polyurethanes
Authors: Cooper Stuart L. , Tobolsky Arthur V.
Published: April 2003

The viscoelastic properties of some polyester‐urethanes are compared with the properties of other polymers. The behavior observed is anomalous in that these polyurethanes exhibit an unusually high value of modulus well above their Tg, unaccounted for by either crosslinking or crystallinity. Various experiments including incorporation of plasticizes of widely varying chemical composition have suggested interpretation of the system as a block copolymer, each block having its own Tg. Each of the two types of blocks seems to associate with similar blocks from other molecules.
Emulsion polymerization of ethylene. IV. Effect of recipe and polymerization conditions on polymer properties
Authors: Mantell Gerald J. , Stryker Harry K. , Helin Arthur F. , Jamieson Donald R. , Wright Charles H.
Published: April 2003

Some Physical, chemical, and solution properties of polyethylene prepared by emulsion polymerization are described and compared with those of conventional high‐pressure polymer. The emulsion polymers contain an unusually large amount of low molecular weight material for the solution viscosities they exhibit. It is this low molecular weight material that contributes to the characteristic low elongation of the emulsion polymer, as well as to its wide distribution of molecular weights. The effect of changes in recipe and in conditions of polymerization on these properties is discussed. It is shown that some of the emulsifier present during polymerization becomes part of the polymer chain.
Polymerization of methyl methacrylate under ultrasonic irradiation. Part II. Polymerization in toluene–dimethyl sulfoxide mixed solvent
Authors: Osawa Zenjiro
Published: April 2003

Polymerization of methyl methacrylate with Grignard reagents in mixed solvent of toluene and dimethyl sulfoxide (DMSO) under ultrasonic irradiation was carried out, and the effects of ultrasonic irradiation in connection with the mixed solvent on the stereoregularity and the properties of the polymers obtained were studied. The yield of polymers decreases with increasing concentration of DMSO in the solvent, and both yield and intrinsic viscosity of the polymers produced than ultrasonic irradiation are lower than those of polymers produced without it. A marked change in the configurational structure, namely, decrease in isotactic structure, is observed at a DMSO: toluene volume ratio of 5:95 in the series without ultrasonic irradiation, while a higher concentration of DMSO 15% by volume is required to obtain similar results in the series with ultrasonic irradiation.
Reflection of soft X‐rays by organic fibers
Authors: Newman Sanford B.
Published: April 2003

An artifact observed in point projection microradiographs of polymeric fiber and filaments obtained with 8‐A. x‐rays is recorded and described. The phenomenon has been related to fiber‐beam geometry and the high reflection efficiency of soft x‐rays for these materials.
Cooperative unfolding of α‐keratin
Authors: Feughelman M.
Published: April 2003

The unfolding of the α‐helices of the microfibrils in α‐keratin fibers such as wool proceeds in a cooperative manner. When a wool fiber is extended in water, the load‐extension curve obtained indicates on the basis of relationships derived from rate process theory, that the number of α‐helical residues n that unfold simultaneously is at least 50. This is probably an underestimation, as fiber diameter variability severely reduced any estimate of the value of n. Other experimental evidence is also indicated that support the existence of considerable mechanical cooperation between α‐helical components.
Behavior of fibers in cumulative extension cycling
Authors: Hearle J. W. S. , Plonsker H. R.
Published: April 2003

The cumulative extension cycling behavior is a combination of the effects of elastic recovery, viscoelasticity, and fatigue. The purpose of this research was to examine the elastic recovery aspects of the behavior. A model behavior idealized to include only elastic recovery was assumed and a computer program written to simulate cumulative extension cycling behavior based upon this idealized model. Tests were performed with an apparatus which removed the sample's slack after each cycle. A comparison of the experimental and computed results yielded an improved understanding of the elastic recovery aspects of the cumulative extension cycling behavior.
Propagation of vinyl polymers on clay surfaces. II. Polymerization of monomers initiated by free radicals attached to clay
Authors: Dekking Henri G. G.
Published: April 2003

The adduct of Kaolin and 2,2′‐azobisisobutyramidine hydrochloride has been used to initiate the polymerization of methyl methacrylate, styrene, styrene‐butadiene, vinyl acetate, chloroprene, acrylamide, and acrylonitrile. Both extractable and nonextractable polymers are obtained. The adduct of bentonite and 2,2′‐azobisisobutyramidine hydrochloride will initiate the polymerization of methyl methacrylate, acrylamide, vinyl acetate, 4‐vinylpridine, and styrene. Both extractable and nonextractable polymers are formed. When the bentonite or the hectorite adducts are more than 99% decomposed prior to the addition of methyl methacrylate, essentially no extractable polymer is formed, but an increased quantity of nonextractable polymer is produced. This is probably due to an increased accessibility of the monomer to the clay's interior surface and a decrease in the rate of chain termination. As is the case of the kaolin adduct, the clay surface of bentonite appears to accelerate the chain growth considerably.
Structural characterization of natural and vulcanized rubber by ozonolysis
Authors: Chakravarty Shom Nath , Sircar Anil K.
Published: April 2003

A quantitative characterization of natural rubber, both as the raw polymer, and unaccelerated vulcanized samples containing different proportions of sulfur and ranging from soft to hard rubber, is reported. A value of 86% of the chains of natural rubber could be accounted for against 37% as reported by Harries assuming that levulinic acid is the sole degradation product. About 5% of the chain is present as a 3,4 structure which gives rise to formic acid in the degraded product. A small amount of sulfuric acid is present in the degradation product from the vulcanized samples, which decreases with the increases in the percentage of sulfur in the stock as well as the cure time. A chromatographic technique for the separation of levulinic, acetic, and formic acid in the presence of sulfuric acid is reported. It is observed that the total amount of carbon main chain escaping sulfuration decreases and the amount of insoluble fraction increases with increasing proportion of sulfur in the stock.
Copolymerization of unsaturated polyester with styrene in inverted emulsion
Authors: Horie Kazuyuki , Mita Itaru , Kambe Hirotaro
Published: April 2003

Copolymerization of unsaturated polyester with styrene in water‐in‐oil (W/O) type emulsion was carried out with the use of various basic compounds as emulsifiers. It was found that a stable, gellike W/O type emulsion of unsaturated polyester resin is formed only when pKa's of the bases are above 6 and their concentrations are higher than some critical value. In these conditions, water can be dispersed in emulsion up to 900% to the resin. By polymerization, the stable W/O type emulsion is transformed to a white solid copolymer which is dry to the touch and which contains 90–95% of initially added water. It was confirmed that the basic compounds react with the carboxylic group of the polyester to form at the water‐resin interface polyester salts, which act as true emulsifying agents. The stabilization mechanism of the emulsion at various concentrations of the polyester salt was investigated, mainly by microscopic observations, and an interpretation of the critical value of emulsifier concentration is proposed.
Alkylaluminum–Lewis base complexes as initiators of vinyl polymerization
Authors: Breslow David S. , Christman Donald L. , Espy Herbert H. , Lukach Carl A.
Published: April 2003

Complexes of aluminum alkyls with Lewis bases catalyze the polymerization of vinyl chloride. Triethylaluminum is most effective, but other compounds of type R3Al, R2AlCl, R2AlH, and LiAIR4 are operable. Dialkylmagnesiums are active, but Grignard reagents, as well as a number of other metal alkyls are inactive. Among Lewis bases, tetrahydrofuran (THF) and tetrahydropyran give the best yields of poly(vinyl chloride). Oxygen bases, such as ethers and esters, are more effective than nitrogen bases, e.g., tertiary amines. Cyclic compounds are better than acyclic ones. The polymerization occurs in a variety of hydrocarbon, chlorinated hydrocarbon, or ether solvents, but especially well in CCl4. Radical polymerization is probably initiated through the reaction R3Al:Base + CCl4 → R2AlCl: Base + R + Cl3C., to form trichloromethyl radical.
Curing of resole‐type phenol–formaldehyde resin
Authors: Katović Zvonimir
Published: April 2003

The process of resole‐type phenol–formaldehyde resins was studied by differential thermal analysis and infrared spectroscopy. It was shown that in neutral media the first reactions that occur are those between free phenol present in the resin and monosubstituted methylol phenol with free reactive positions on the benzene ring. The formation of methylene linkages is followed immediately by the condensation of methylol groups to give dibenzyl ether linkages. These are subsequently destroyed at about 210°C. It is believed that the entire curing process is governed by a free‐radical mechanism. It is also shown that oxidation of the resin occurs slowly at room temperature and humidity.
Kinetics of the formation of dibenzyl ether linkage during curing of resole‐type phenol–formaldehyde resin by DTA and infrared spectroscopy
Authors: Katović Zvonimir
Published: April 2003

The kinetics of formation of dibenzyl ether linkages during cure of resole‐type phenol‐formaldehyde resins was studied by the use of differential thermal analysis and infrared spectroscopy. The activation energy was 21.6 kcal./mole by the Borchard and Daniels method gives and 18.6 kcal./mole by the Kissinger method. For the same process, infrared, which shows a rather good agreement between the two different methods. The heat of reaction, determined from the area under the DTA curve for the corresponding reaction, was found to be 20.2 cal./g.
Graft copolymerization of vinyl monomers in wool fibers
Authors: Negishi Michiharu , Arai Kozo , Okada Sadayuki
Published: April 2003

Graft copolymerization of vinyl monomers, mainly methyl methacrylate, in reduced, successively alkylated, or KCN‐Treated wool fibers was performed in the redox LiBr–persulfate system without homopolymer. The reduction gives a striking effect in promoting the graft copolymerization. Methylation or ethylene recrosslinking of the reduced wool, especially the former, decreases the graft‐on remarkably. By the KCN treatment in which the conversion of disulfide to lanthionine bonds occurs, the grafting is decreased in the bromide–persulfate system but promoted in the system with persulfate alone. Methylation or KCN treatment of wool as well as reduction brings about a great increase in the absorption of persulfate. The grafting of the lanthionine‐containing wool in the redox system accompanied by the liberation of bromine might be retarded by the pronounced bromination of monomers over the inhibiting of homopolymerization, because the lanthionine bonds are more stable to bromine than the disulfide bonds. In general, disulfide bonds and the other easily oxidized components of wool may perhaps play an important role in regulating the bromination of monomers and in the graft copolymerization without homopolymer. The molecular weight of graft polymer is decreased distinctly with increasing extent of reduction of wool. From these results, the thiol groups on wool are considered to give predominantly graft centers by the radicalotropy from SO4, OH·, and/or Br·.
Analysis of the Maxwell orthogonal rheometer
Authors: Blyler L. L. , Kurtz S. J.
Published: April 2003

An analysis of the Maxwell orthogonal rheometer for polymer melts is made by using the constitutive equation of White and Metzner. The results indicate that the shear deformation involved is oscillatory and that the storage and loss moduli of the melt may be derived from the measured stress response.
Estimation of kinetic parameters during pyrolysis from linearized DTA traces
Authors: Reich Leo
Published: April 2003

A method which empolys the linearization of DTA traces is presented for the estimation of kinetic parameters during polymer pyrolysis. By this method, two DTA traces are used, changes in mechanism with conversion may be detected, and it is not necessary to measure areas prior to evaluating activation energy and reaction order. The method is applied to polyethylene, polypropylene, and polystyrene. The agreement between observed and reported values of kinetic parameters is good. Advantages and disadvantages of the method are discussed.
Interaction of CO2 with a series of detached organic films
Authors: Slabaugh W. H. , Kennedy G. H.
Published: April 2003

Data obtained from gaseous sorption isotherms of CO2 on eight organic films at three temperatures and three pressures were evaluated for evidences of chemisorption and physical adsorption. The rates of sorption, affected by both temperature and pressure, were analyzed by calculating the perameters of the Elovich equation and those of Barrer's solution of Fick's law for diffusion. Through a consideration of the Elovich parameters, the sorption coefficients, the limiting diffusion coefficients, and the activation energies for diffusion it appears that the rate of interaction of CO2 with these organic films is primarily a diffusion‐controlled process.
Antiplasticization. II. Characteristics of antiplasticizers
Authors: Jackson W. J. , Caldwell J. R.
Published: April 2003

By the incorporation of certain types of additives in bisphenol A polycarbonate, the modulus and tensile strength of the films are increased and the elongation is decreased. This effect is called antiplasticization, because the opposite results are obtained on plasticization—decreased modulus and tensile strength and increased elongation. A study of these additives indicated that antiplasticizers are compounds which are comptiable with the polymer and which (1) contain polar atoms such as halogen, nitrogen, oxygen, or sulfur, (2) contain at least two nonbridged rings, (3) have a glass transition temperature greater than −50°C., and (4) have one dimension less than about 5.5 A. in at least 65% of the length of the molecules.
Antiplasticization. III. Characteristics and properties of antiplasticizable polymers
Authors: Jackson W. J. , Caldwell J. R.
Published: April 2003

Antiplasticization is applicable to polymers which contain rigid, polar groups and stiff chains, such as many bisphenol polycarbonates and polyesters, 2,2,4,4‐tetramethyl‐1,3‐cyclobutanediol polycarbonates and polyesters, cellulose triacetate, and a commercial poly(sulfone ether). The stiffness, hardness, and tensile strength of these polymers are increased by antiplasticizers, and the elongation, impact strength, and heat‐distortion temperature are decreased. The stiffness of antiplasticized polymers can be further increased by crystallization. A clear, hard, stiff, tough, self‐extinguishing molding plastic with good electrical properties and improved resistance to stress cracking is obtained by antiplasticizing bisphenol A polycarbonate with 20% Aroclor 5460.
Studies on melt spinning. II. Steady‐state and transient solutions of fundamental equations compared with experimental results
Authors: Kase Susumu , Matsuo Tatsuki
Published: April 2003

In the part installment of the present paper, the authors formulated the dynamics of melt spinning by introducing a set of fundamental equations that consist of the equations of heat, force, and material balances. Some steady‐state solutions were also given. Additional steady‐state solutions corresponding to many different spinning conditions for polyester and polypropylene filament yarns consistently show good agreement with experimental results. These steady‐state solutions that give filament cross‐section A (x) and filament temperature t(x) as functions of position x are correlated with yarn qualities: yarn density and birefringence, crystallinity and molecular orientation, are correlated respectively with the speed of Polymer cooling at 100°C. and the maximum tensile stress (F/A)w acting on the filament. A transient solution of the fundamental equations computed on an IBM 1401 machine shows that the filament cross‐section A at the take‐up roll forms a large transient peak after a stepwise increase in the speed vy of cooling air. This agrees with experiments fairly well. The fundamental equations, therefore, clarify the dynamic relations between cooling air speed and yarn weight variations.
Resistance of Valonia cellulose to mercerization
Authors: Okajima Saburo , Kai Akira
Published: April 2003

The mercerization behavior at 20°C. of Valonia macrophysa cellulose of Japanese origin was investigated by x‐ray, moisture regain, and infrared spectrographic methods. The NaOH concentration range necessary for mercerization was 16–20%, which is higher than those required for wood pulp (8–11%), ramie or cotton (11–14%), and even the animal cellulose, Tunicin (14–16%). Treatment with the alkaline solution of the ordinary concentration (17.5%) for 4 days could not mercerize it, and even mercerization with a 19% solution brought about the presence of the reflection from (101)II along with those from (101)I and (101)I after regeneration. Such a high resistance to mercerization of the Valonia cellulose may be due to its larger crystallite size rather than the crystalline content.
Thermal stability of model compounds related to thermostable polymers by pyrolysis‐gas chromatography
Authors: Hirsch Stephen S. , Lilyquist M. R.
Published: April 2003

Thermal stabilities of eighteen model compounds related structurally to thermostable polymer systems were determined accurately by pyrolysis‐gas chromatography. This approach offers distinct advantages over previously used indirect methods which measure parameters other than actual starting material remaining undecomposed. Both the oxadiazole ring and the aromatic amide link were found to have poor thermal stabilities in comparison with other compounds studied. Since polymers based on these two features have been shown to be valuable for use in air at 200–400°C., the data suggest that oxidation resistance rather than the ultimate in pure thermal resistance should be sought in all‐purpose thermostable materials.
Foams produced from sulfur dioxide and various polymers
Authors: Sherr Allan E. , Carlin Joseph
Published: April 2003

A variety of polymers have been foamed with sulfur dioxide. Properties of the foams could be varied by choice of polymer to produce rigid, semirigid, flexible, rubbery, fibrous, self‐extinguishing, and/or heat‐resistant materials.
Elastomer processing and application of rheological fundamentals
Authors: White James L. , Tokita Noboru
Published: April 2003

Elastomer processing operations are discussed and classified as unit operations. The theory of nonlinear viscoelasticity is applied to processing unvulcanized amorphous rubber and the significance of the maximum relaxation time τm is emphasized.
Density–dose behavior of irradiated polytetrafluoroethylene
Authors: Scherer A. E. , Kline D. E.
Published: April 2003

The nature of the room temperature density–dose relationships in polytetrafluoro‐ethylene (PTFE) have been studied over the dose range of 104 to 109 rads. Under various conditions, samples of PTFE were irradiated in combinations of neutron and gamma (reactor and 60Co) radiation fields resulting in density increases up to approximately 5%. For the dose range 105 to 108 rads, the increase in density measured at 0°C. is approximately proportional to the logarithm of the radiation dose. For doses less than about 105 rads, the increase in density appears to be directly proportional to the dose, while above 108 rads the density reaches a maximum and then begins to decrease. By examining the changes in slope and displacement of the curves which occur under various conditions, several effects are discernible. Compared to the effects of γ‐rays alone, the density increase per dose in the 105 to 108 rad region is lower for cases where both neutrons and γ‐rays are present in the radiation field. This may suggest that competing processes are involved in producing density changes. The discernible difference between effects of γ‐radiation and reactor radiation appears to be unique in polymers. The ambient temperature during irradiation and the post‐irradiation heat treatment of the specimens affect the changes in density. For dose rates over the range 0.1 × 106 to 13 × 106 rads/hr., no dose rate effects have thus far been observed. The feasibility of using PTFE for some types of radiation dosimetry has been demonstrated, and its possible usefulness is being investigated.
Effects of interfaces on the thermal degradation of polymer–metal composites
Authors: Schmidt G. A. , Gaulin C. A.
Published: April 2003

Previous studies by Black and Blomquist on the degradative failure of polymer–metal adhesive bonds have shown that composite failure depends largely on the type of metal substrate employed. In the work reported herein, metal powders of high surface area have been employed to maximize the metal–polymer interface. The composite systems studied consisted for aluminum and iron with polycondensates of bisphenol A–diglycidyl ether, phenol–formaldehyde and poly‐2,2′‐(m‐phenylene)‐5,5′‐bibenimidazole. The composites were prepared in the absence of air and thermally degraded in a time‐of‐flight mass spectrometer while the degradation products were continuously monitored from mass 1 to 200. In the polymer and polymer–metal systems investigated, iron accelerated the decomposition of all polymers studied. This was determined by plotting m/e against degradation temperature for the more common mass peaks such as hydrogen and carbon monoxide for the carbon–hydrogen–oxygen‐containing polymer and hydrogen cyanide and ammonia for the carbon–hydrogen–nitrogen‐containing polymer. This technique offers promise in determining the nature of the interface as well as the effect of the interface on polymer degradation.
Physikalische messungen an einem kunststoff als optischem medium
Authors: Lasch Margarete , Rudolph Friedrich , Schreiner Ludwig , Schulze Horst
Published: April 2003

Vorliegende Arbeit befasst sich mit der Möglichkeit, Diäthylenglycol‐bisallylcarbonat Polymerisate als optisch wirksame Bauelemente zu verwenden. Es wird die Problemtik der Herstellung des Materials und der Formgebung dargestellt. Bei der Diskssion der Eigenschaften des Polymerisates werden Messmethoden und ‐probleme erörtert, z.B. hinsichtlich der Steuerung des Polymerisationsvorganges, der Widerstandsfähigkeit des Polymerisates gegenöber mechanischen Oberflächenbeschädigungen und Klimaein‐ flüssen. Die Arbeit zeigt, dass Diäthylenglycol‐bisallylcarbonat die Reihe der bisher in der Optik verwendeten Kunststoffe in wertvoller Weise ergänst. Bezüglich der Beständigkeit gegen mechanische Oberflächenbeschädigungen wird gezeigt, dass eine Steigerung und Weiterentwicklung möglich ist; das ist gleichzeitig ein Beitrag zum Formulierung und Standardisierung des Begriffes Wischfestigkeit.
Mixing of carbon black and polymer: Interaction and reinforcement
Authors: Boonstra B. B.
Published: April 2003

Interaction between carbon black and polymer starts during the mixing process; a primary agglomerate is formed, the composition of which is dependent upon the structure. The important carbon black properties are surface area, specific activity, structure (void, volume, anisometry), and porosity of the particles. On heat treatment of black at 3000°C., it loses its sites of high specific activity. Structure and specific activity determine incorporation time and further dispersion. During mixing, bound rubber is formed which is used as a measure of specific surface activity. In the final vulcanizate, the filler–polymer interaction is evident in reduced swelling in solvents (benzene, chloroform, cyclohexane,) etc. Below a certain critical degree of swelling, the percentage swelling is no longer dependent upon the amount of filler in the vulcanizate. Graphitized black vulcanizates exhibit in all solvents the same degree of swelling as the unfilled vulcanizate. This phenomenon is explained by the assumption of mobile adsorption of rubber chains on the carbon black surface. In untreated blacks the mobility on the surface is limited by sites of high energy of adsorption. In graphitized blacks such sites are no longer found, and swelling is unhindered by the presence of black. Reinforcement is explained by the more homegeneous distribution of tension between molecular chains due to slippage on the carbon surface.
Effect of temperature on the permeation of water through propylene glycol monoacrylate hydrogel
Authors: Refojo Miguel F.
Published: April 2003

Transparent propylene glycol monoacrylate (PGMA) hydrogels become reversibly opaque when the temperature is rapidly increased to above 30°C. Water permeation, driven by a hydrostatic pressure difference through three PGMA membranes differing in water content and thickness was determined at several temperatures. At room temperature, the permeability to water is relatively low (less than 10 × 10−16 cm.2) and is dominated by a diffusion mechanism. When the temperature is suddenly increased, the water permeation rises quickly (up to fifteen times or more depending on the temperature), and viscous flow predominates over diffusive flow. The rapid flow slows down after some time at the same temperature, or on lowering the temperature, and may be interpreted as caused mainly by the reversible transformation of the membrane from the heterogeneous to the homogeneous form. When the temperature is increased gradually, the permeability of the membrane is in the same order of magnitude as that found at room temperature, because no phase separation occurs. The permeation of water decreased in successive measurements made under the same pressure gradient. An increase of the pressure difference also resulted in decreased permeation, indicating that water was pressed out of the gel. Dehydration of the gel caused by increases in temperature (exothermic swelling) and in pressure and changes in the viscosity of water with temperature are some of the factors which are considered in the interpretation of the results.
Reversible gelation of acrylonitrile–vinyl acetate copolymer solutions
Authors: Paul D. R.
Published: April 2003

The reversible gelation of acrylonitrile–vinyl acetate copolymers in concentrated solutions has been studied with the use of various solvents. These concentrated solutions gel or become rigid with time, but they become fluid again when heated above a certain temperature called the gel melting point. A technique involving the use of mercury drops was developed to measure this transition. This temperature was evaluated as a function of solids level, water content in the solvent, and the amount of vinyl acetate in the copolymer, dimethylacetamide being used as the solvent. Four other solvents were used to obtain limited data. Gel melting was studied further by differential thermal analysis and shear modulus measurements. The results are discussed in terms of network formation and solubility. The x‐ray diffraction results imply that the tie points of the gel are crystalline.
Colloidal macromolecular phenomena. Part II. Novel microcrystals of polymers
Authors: Battista O. A. , Erdi N. Z. , Ferraro C. F. , Karasinski F. J.
Published: April 2003

Colloidal microcrystalline cellulose, introduced in 1961, now is a successful commercial product with growing world‐wide markets. This paper describes some major findings of our continuing research to convert fibrous or fiber‐forming polymer systems into new colloidal microcrystalline physical states without going through a homogeneous molecular solution phase. Several novel microcrystalline colloidal products from the following natural and/or synthetic polymeric raw materials are described and compared for the first time: cellulose, amylose, collagen, nylon, and chrysotile mineral silicates. Many previously unpublished electron micrographs are presented. These products demonstrate a new and growing field of colloidal microcrystalline polymer science. They open up increasing opportunities for new polymer products based on the original concept, namely, the unhinging of polymer microcrystals from their natural or synthetic network and then by appropriate mechanical energy, releasing them as discrete, submicron colloidal polymer microcrystals dispersed in various liquid media to form unique gel systems, or reaggregated in the dry state to form porous colloidal particles.