bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of the surface free energy of polymers
Authors: Owens D. K. , Wendt R. C.
Published: April 2003

A method for measuring the surface energy of solids and for resolving the surface energy into contributions from dispersion and dipole‐hydrogen bonding forces has been developed. It is based on the measurement of contact angles with water and methylene iodide. Good agreement has been obtained with the more laborious γc method. Evidence for a finite value of liquid‐solid interfacial tension at zero contact angle is presented. The method is especially applicable to the surface characterization of polymers.
Kinetic studies on the cellulose–propylene system in presence of Ziegler‐Natta catalysts
Authors: Dankovics A. , Erdélyi J. , Koltai M.
Published: April 2003

Kinetics of the uptake of polypropylene by the cellulose were studied. According to the experimental results, the reaction begins with an induction period which cannot be explained on the basis of the reaction mechanism of Ziegler‐Natta catalysts. Most probable reason of this period may be the initial unsaturation of the system.

Studies on the effect of concentration of the catalyst (TiCl4) showed that, above the order of magnitude of 10−2 mole/l, uptake of polypropylene by the cellulose is directly proportional to the concentration of TiCl4. The maximum catalytic activity was observed at the molar ratio of AlEt3 to TiCl4 equal to 1.5.

Concentration of propylene supported by the cellulose can be increased by elevation of the temperature.

By increasing the concentration or the specific surface area of the cellulose at a constant concentration of the cellulose at a constant concentration of the catalyst, a kind of saturation appears on the cellulose fibers with respect to the adsorption of the metal chloride. Thus, increasing the specific surface area does not involve an increase in the uptake of polypropylene, in fact, increasing the concentration of the cellulose results in a drop in the amount of propylene to be taken up.

On the basis of the infrared spectroscopical and the X‐ray diffraction results, no differences were found between the mechanical mixture of the components and the cellulose fibers coated with polypropylene.

Mechanical strength of paper sheets was poor compared with that of sheets from pure cellulose. Cellulose encapsulated with polypropylene can be used in the paper industry as an interlayer in laminated papers.
Photodegradative wavelength dependence of thermally resistant organic polymers
Authors: Johnson L. D. , Tincher W. C. , Bach H. C.
Published: April 2003

The wavelength dependence of photodegradation of three “high temperature” aromatic polyamide polymers has been very accurately determined by means of a fast grating spectrograph used in conjunction with a high pressure xenon arc. One of these polymers, the poly‐(isophthalamide) of 4,4′‐bis(p‐aminophenyl)‐2,2′bithiazole, was found to be degraded significantly by visible light, especially that of 4140 Å, wavelength. Both the poly‐terephthalamide of 1,3‐bis(3‐aminobenzamide) benzene and Du Pont Nomex, also an aromatic polyamide, were damaged primarily by radiation in the near ultraviolet region. Degradation band maxima for these polymers were observed at 3700 Å, and 3600 Å, respectively. All three thermally resistant polymers were thus found to be degraded by light of much longer wavelength than that which is harmful to other common polymers.
Radiation chemical studies of protein reactions: Effect of post‐irradiation on viscosity
Authors: Nisizawa Mizuho
Published: April 2003

Protein was irradiated by gamma rays from a cobalt 60 source. At different times after irradiation, the reactivity decay of the irradiated protein was examined. An empirical equation for the reactivity decay was obtained.
Prediction of mechanical properties of polymers. Tensile strength of glass‐reinforced plastics
Authors: McAbee Elise , Levi David W.
Published: April 2003

Tensile strength data at high and low rates of loading were obtained for a glass‐reinforced polyester and a glass‐reinforced epoxy. Analysis of the data by a rate method indicated that such a method may be used to predict behavior of polymers from limited test data.
The measurement of charge response of powders exposed to ion bombardment
Authors: Zabel Lowell W. , Estcourt Allan R.
Published: April 2003

A system has been designed and developed to subject a sample of powder on a grounded metal plate to charging by ion bombardment and to measure the charge accepted by the sample. Observation of the charge decay from the sample was also possible. A method of sample preparation was evolved which made it possible to obtain samples of known particle size and number of particles. The sensitivity of measurement and the noise levels were investigated and found to be acceptable. Calibration tests were made to determine the validity of the proposed equation relating the measured voltage, circuit capacitances, and the ratio of probe height to net charge location. It was found that for a wide range of values of the ratio of probe height to particle diameter, the linear equation was a good description of the process and could be used to accurately determine the charge on a sample. Some measurements were made on typical powders to illustrate the feasibility of the method and equipment to characterize variable charging properties.
A study of the surface‐catalyzed polymerization of ethylene on chromic oxide–silica–alumina catalysts
Authors: Whitaker H. L. , Wills G. B.
Published: April 2003

This investigation was an exploratory study of the phenomena associated with the polymerization of ethylene on a chromic oxide–silica–alumina catalyst. The polymerization was carried out in a batch reactor fed on demand at 500 psi gage and at 135°C. The catalyst was 3% chromic oxide on an 87% silica–13% alumina support, activated at 450°C for 5.25 hr in dry air. The catalyst particles were found to reduce in size during the polymerization. The particles decreased in size from 18/20 mesh to an average diameter of 9.6 μ. This reduction in particle size was found to cease at a yield of 40.0 g per gram of catalyst. By determining the monomer reaction rate versus time, the catalyst activity was found to change greatly during the polymerization. The activity increased to a maximum, then decreased. The period of increasing catalyst activity corresponded to the period of catalyst particle size reduction. The period of decreasing activity was considered to be due to the build‐up of a polymer film diffusion layer and true catalyst deactivation. The molecular weight distributions for a series of samples from each polymerization test were determined on gel permeation chromatograph. These distributions for each test were characterized by an increase in the high molecular weight tail as the yield increased, while the peak position and low molecular weight end remained essentially constant.
Urethanes. I. Organometallic catalysis of the reaction of alcohols with isocyanates
Authors: Abbate F. William , Ulrich Henri
Published: April 2003

The catalysis of the reaction of n‐butyl alcohol with isocyanates, using organometallic derivatives of lead, tin, and mercury, has been investigated. The rate of the reaction was measured by following the disappearance of the isocyanate absorption in the infrared. Phenyl, n‐butyl, and cyclohexyl isocyanate were chosen to represent typical aromatic primary and secondary aliphatic isocyanates. Within the same series of catalysts, RnMOAc, the catalytic effect decreases in the order RHg > R3Sn > R3Pb; and in all cases R = aryl > R = alkyl. The electronic effects of substituents on the aryl moiety are not pronounced. Changes in X of RnMX greatly affect the catalytic activity. The mechanism of organometallic catalysis of the alcohol‐isocyanate reaction occurs via a template‐type mechanism whereby the catalyst acts to complex both reactants in a catalyst phase allowing the reaction to occur with greater facility.
Thermal decomposition of Cu(II)‐bis(8‐hydroxy‐5‐quinolyl)methane coordination polymer
Authors: Brown James E. , Tryon Max , Horowitz Emanuel
Published: April 2003

The volatile products formed when the coordination polymer of copper(II) and bis‐(8‐hydroxy‐5‐quinolyl)methane was heated in vacuum at elevated preselected temperatures were examined. The amount of weight loss at each temperature was determined with a recording thermal balance at each fixed temperature. Infrared spectrophotometry was used to aid in the identification of the major volatile component. A sample was pyrolyzed directly into the mass spectrometer. The results show that the volatile product is for the most part the organic ligand bis(8‐hydroxy‐5‐quinolyl)methane and not derivatives of the copper complex or fragments of the ligand. The mechanism for the decomposition previously proposed is supported.
Influence of structure of cyclic urea derivatives on their reactivities with cotton
Authors: Jung H. Z. , Benerito R. R. , Gonzales E. J. , Berni R. J.
Published: April 2003

The structure of the cyclic urea influenced the rate of reaction with cotton cellulose and the mechanism by which reaction occurred. Reaction of N, N′‐dimethylolethylene‐urea (DMEU) and N, N′‐dimethylolpropyleneurea (DMPU) with cellulose in presence of inorganic salt catalysts proceeded through methylol hydroxyls and at the same rate; but reaction mechanism differed. With DMEU, N → metal ion coordination occurred and SN2 mechanism prevailed. With DMPU, O → metal ion coordination resulted.

Reaction of dihydroxyethylene urea (DHEU), N, N′‐dimethyldihydroxyethyleneurea (DMeDHEU), and N, N′‐dimethyloldihydroxyethyleneurea (DMDHEU) with cotton cellulose proceeded through ring hydroxyls with the formation of a carbonium ion, indicating an SN1 mechanism. The much faster rate of reaction with DMeDHEU than with DHEU was attributed to the more electronegative environment of its ring hydroxyl, while the much slower rate of reaction of DMDHEU was attributed to hydrogen bonding between its methylol and ring hydroxyls.
Shear properties of polystyrenes in the transition region
Authors: Burge David E.
Published: April 2003

Shear properties of commercially available polystyrenes with narrow molecular weight distribution have been measured in the transition region from 100°C to 150°C and over a frequency range from 50 Hz to 1000 Hz. The effect of molecular weight or shear properties is established with four polymers ranging in molecular weight from 20,000 to 860,000. A broad, bimodal distribution is also studied. The properties of these polymers, with two different diluents added, illustrate the rather marked qualitative difference in effects caused by diluents.
Thermal degradation of polymers. Part III. Vacuum pyrolysis of poly(m‐aminostyrene); the products volatile at pyrolysis temperature which are liquid or gaseous at room temperature
Authors: Still R. H. , Jones P. B.
Published: April 2003

The products obtained on degradation of poly(m‐aminostyrene) in vacuo are described. The effect of molecular weight and pyrolysis temperature are discussed and the behavior of poly(m‐aminostyrene) compared with that of polystyrene. Quantitative analytical methods using ultra‐violet spectroscopy and gas liquid chromatography are described for m‐aminostyrene and m‐toluidine. The possible mechanisms of degradation to yield the products are discussed.
Crazing, yielding, and fracture of polymers. I. Ductile brittle transition in polycarbonate
Authors: Legrand D. G.
Published: April 2003

Most thermoplastics far below their glass transition give a brittle fracture when de‐formed in uniaxial tension. Bisphenol‐A polycarbonates are an exception and deform in a ductile manner. However, it has been observed in Izod impact studies of notched samples that the mode of failure changes from a ductile to a brittle fracture on annealing samples below Tg. It has been found that, when notched samples are stressed, a Griffith type flaw is formed under the notch. The criterion for the ductile brittle transition is evaluated in terms of σG (the stress required to propagate the Griffith flaw), and σy, the yield stress for the polymer. It has been found that the density and yield stress for the samples annealed at various temperatures are dependent upon previous thermal history and in particular on the molecular weíAght. On the basis of these measurements, it is concluded that many of the so‐called anomalous effects observed with polycarbonate can be explained.
Polyacrylic desalination membranes. I. Synthesis and characterization
Authors: Hoffman Allan S. , Modell Michael , Pan Peter
Published: April 2003

A new class of desalination membranes has been developed. The membranes were prepared by polymerizing mixtures of two hydrophilic monomers (N‐methyloacrylamide and acrylic acid), a hydrophobic monomer (ethyl acrylate) and a hydrophobic crosslinking monomer (trimethylol propane trimethacrylate) followed by heat treatment. The membranes were homogeneous, averaging about 6 mils in thickness. They were characterized by measuring water contents and salt distribution coefficients using an immersion technique. The fractional water contents in the membranes varied between 0.16 and 0.44 as the molal salt distribution coefficients increased from ca. 0.22 to 0.43. Increasing contents of the hydrophobic monomer and/or crosslinking monomer led to decreased water and salt contents, as expected. A model is postulated in which the water is assumed to be distributed within the polymer in two forms: (1) as primary water, hydrogen‐bonded with hydrophilic polymer groups, and (2) secondary water, imbibed with salt from the external solution into hydrophilic regions or defects within the polymer matrix. It was found that primary water content was approximately constant for all compositions and varied between ca. 2–3 moles of primary water/mole of hydrophilic monomer in the membrane.
Quantitative study of the annealing of poly(vinyl chloride) near the glass transition
Authors: Foltz Carl R. , McKinney Paul V.
Published: April 2003

Poly(vinyl chloride) displays a normal DSC of DTA curve for the glass transition when quenched from above its Tg. However if cooled slowly or annealed near the glass transition temperature, a peak appears on the DSC or DTA curve at the Tg. In this paper quantitative studies of the time and temperature effects on the production of this endothermal peak during the annealing of PVC homopolymer and an acetate copolymer are presented. The phenomenon conforms to the Williams, Landell, and Ferry equation for the relaxation of polymer chains, the rate of the peak formation becoming negligible at more than 50°C below Tg. The energy difference between the quenched and annealed forms is small. For a PVC homopolymer annealed 2 hr at 68°C, which is Tg −10°C, the difference is 0.25 cal/g. For a 13% acetate copolymer of PVC similarly annealed, the difference is 0.36 cal/g. The measured rates of the process give a calculated activation energy of 13–14 kcal/mole for PVC homopolymer and copolymer. This appearance of a peak on the Tg curve for a polymer when annealed near the glass temperature appears to be a general phenomenon.
Chemically crosslinked polyethylene: Modulus‐temperature relations and heat stability
Authors: Narkis M. , Tobolsky A. V.
Published: April 2003

The influence of MT black concentration on the shear modulus of low‐density crosslinked polyethylene can be approximated by the Guth–Gold equation, at temperatures below the crystalline melting zone. Above the melting zone shear modulus does not depend practically on the carbon black level. At high temperatures both degradation and crosslinking reactions are taking place. The variation of the shear modulus with temperature due to these reactions is shown for various carbon black loadings. A preliminary chemical stress‐relaxation study at 250°C is presented.
Radiation chemical studies of protein reactions: Radiation dose and optical rotation
Authors: Nisizawa Mizuho
Published: April 2003

When protein was irradiated by gamma rays from a cobalt 60 sources, an activated state on the position of the groups in the vicinity of the asymmetric carbon atoms in the protein molecule was caused. An empirical equation for the change in optical rotation was obtained, and the phenomena were explained on the basis of the molecular mechanism. The general equation for the change in optical rotation is given by [α] = (b + a log R) (1 − e−kt), where [α] is the specific rotation of the solution, R is the gamma radiation dose, t is time, and a, b, and k are adjustable constants.
Cooking schedule of alkyd resin preparation. I. Effect of cooking schedule on viscosity‐molecular weight relationship
Authors: Nagata Takumi
Published: April 2003

The two constants in the equation log η = A + C′ M̄n1/2 (η is the viscosity of molten alkyd and M̄n the number average molecular weight) were determined at 110°C for two kinds of alkyd resin prepared with the same formulation but with different cooking schedules. It was found that the magnitude of the slope C′ was larger for the alkyd which was prepared by raising the reaction temperature directly up to 230°C, in comparison with that of the alkyd which was prepared by maintaining the temperature at 170°C for an hour and then raising it up to 230°C.

Measurements of η and M̄n were carried out until the gelation occurred. Both upward and downward breaks were observed in log η vs. M̄n1/2 plot. Based on these viscometric data, the gel point mechanism was discussed. Disagreements between the molecular weight observed and that calculated from the Flory's theoretical equation became more remarkable as the esterification proceeded. This suggested that a large extent of intraesterification reaction is taking place in alkyd synthesis.
Load–compression behavior of flexible foams
Authors: Rusch K. C.
Published: April 2003

The load–compression behavior of a foam reflects its geometric structure and the physical properties of the matrix polymer. Quantitative relations between these parameters have been established in the present study. Based on both theoretical analyses and experimental data obtained on a flexible polyurethane foam, it is shown that the compressive stress can be factored into the product of two terms: (1) a dimensionless function of the compressive strain, ψ(ε), calculated from experimental load–compression data and reflecting the buckling of the foam matrix; and (2) a factor, εEf, where Ef is the apparent Young's modulus of the foam (which is a function primarily of the modulus of the base polymer E0 and of the volume fraction of polymer, φ). Thus the compressive stress behavior of a foamed polymer is determined by E0, φ, and the matrix geometry, the latter described by the function ψ(ε). Using these established relations, it now is possible to delineate precisely the structural features a foam must possess—density, cell shape and size distribution, and modulus of the base polymer—to meet a given load–compression specification.
The manganic hydroxide–hydrazine hydrate system as an initiator of vinyl polymerization
Authors: Bond Joan , Longbottom H. M.
Published: April 2003

The reaction of hydrazine hydrate with manganic hydroxide and its application to the solution polymerization of methyl methacrylate has been studied. The kinetic evidence suggests that the hydrazine and the monomer are both adsorbed on the surface of the manganic hydroxide sol and that the decomposition of the hydrazine and the polymerization of the methyl methacrylate follow zero‐order kinetics. The rate of polymerization increases slowly with increasing temperature, the activation energy for the polymerization being 4.9 ± 0.2 kcal/mole.
An investigation of factors relating to the exudation of polyester plasticizers from poly(vinyl chloride)
Authors: Rushton Brian M. , Salomons Norman S.
Published: April 2003

Poly(vinyl chloride) (PVC) was plasticized with a given polyester. The resulting exudate under humid conditions was qualitatively analyzed by GPC and GLC. The exudate was found to have a greater concentration of low molecular weight species than the origional polyester. Further, a much higher hydroxyl group concentration was present. The described polyester was also fractionated and characterization studies were performed. The relative migratory aptitude in PVC of these moieties was studied under humied conditions. The fraction with the greatest concentration of low molecular weight species and the highest hydroxyl concentration was exuded first.
Estimation of Mw from dilute solution viscosity
Authors: Rudin A. , Bennett G. W. , McLaren J. R.
Published: April 2003

The viscosity‐average molecular weight, Mv, of a polymer is given operationally through its limiting viscosity number [η] and the Mark‐Houwink equation [η] = KMvα, where K and α are empirical constants. If [η] is measured under different conditions, α and Mv will vary for the same sample. Mvα is the α‐order moment about the origin of the differential weight distribution of the polymer. Practically, the results of a series of Mv measurements on the same polymer are equivalent to a cluster of fractional moments of the weight distribution, with orders between 0.55 and 0.80. It is shown that the first moment of this distribution, Mw, may be estimated reliably by a straightline plot of Mv against α‐extrapolated to α equals 1. This simple expedient is effective although there are probably no molecular weight distributions in which the relation is strictly linear and there are no mathematical distributions for which the αth root of the αth moment is a linear function of α for all α. The deviation from linearity is small enough, however, that the real curve can be represented by a straight line over a short range of α. Thus, Mw can be measured accurately, but Mn, Mz, or the breadth of the distribution is not accessible by this method. Experimental and literature examples show that the precision of Mw estimated by this method compares well with that of primary methods for measuring this molecular weight average. If a linear relationship is observed with reliable α values, this appears to be a sufficient condition for estimation of a valid Mw.
Properties of blends containing petroleum jelly and 4‐methyl‐pentene‐1 (TPX‐RT‐D30)
Authors: McCann J. P. , Geacintov C.
Published: April 2003

The properties of 4‐methyl‐pentene‐1 polymer (TPX‐RT‐D30) were altered by blending petroleum jelly (P.J.) with the polymer. The polymer was blended with up to 40% by weight P. J. The plasticization of the polymer by the P. J. apparently allows high molecular weight fractions of the polymer to crystallize and influences the crystalline size and perfection. Tensile properties of the blends showed both a break and yield value in all ratios as compared to only a break value for the pure polymer. Breaking strength ranged from 4000 psi for the polymer to 1000 psi at 40% P. J. The samples had a “necking down” effect at 10% P. J. Modulus decreased from 1.8 × 104 (literature value 2.1 × 105) to 2.3 × 104 at 40% P. J. Brittle point values varied from above room temperature to 5°C at 40% P. J. The Vicat softening point ranged from 181°C for the polymer to 87°C at 40% P. J. Differential thermal analysis (Stone) showed a melting point depression from 235°C to 218°C at 40% P. J.
Thermal conductivity, specific heat, and dynamic mechanical behavior of diglycidyl ether of bisphenol a cured with m‐phenylenediamine
Authors: Kreahling R. P. , Kline D. E.
Published: April 2003

The thermal conductivity, specific heat, and dynamic mechanical behavior of an epoxide system have been investigated over a relatively wide temperature range. Effects of nonstoichiometric amine concentrations and postcure heat treatments were included in the study. The thermal conductivity behavior was found to be related to the extent of cure of the poxy system, but in general the results were typical of an amorphous polymer. Calorimetric determinations were used to study the curing reaction and the glasslike transition temperature for the various systems. Dynamic mechanical results were employed to delinearte the various internal relaxations of the cured materials and in some instances to permit correlation of relaxations with the thermal conductivity and the specific heat results. From comparison of present results to those of a previous paper, the activation energy for the relaxation process occurring near 270°K has been estimated to be 16 kcal/mole.
Determination of the extent of reaction for the system carboxyl‐terminated polybutadiene‐epoxide beyond the gel point by infrared spectroscopy
Authors: Strecker R. A. H.
Published: April 2003

Curing reactions were investigated after the gel point, using infrared transmittance and reflection spectrophotometric techniques. In the system carboxyl‐terminated polybutadiene (CTPB)/Epon X801 or Epotuf STF‐6, catalyzed with Fe(III)‐acetyl‐acetonate (FeAA), at an equivalent ratio of carboxyl to epoxide groups, the final extent of reaction of COOH groups was found to be between 64% and 77% for eight CTPB samples. Increasing the ratio of epoxide to carboxyl groups (up to 1.6) resulted in an increase in the conversion, but the complete reaction of COOH groups could not be accomplished. The final extent of reaction also depends upon the functionality of the crosslinking agent. The lower the functionality of the epoxide, the higher the conversion of COOH groups. The use of chromium naphthenate as a catalyst for epoxide–COOH reactions gave higher conversions than FeAA. This result is related to side reactions catalyzed by the chromium naphthenate. The change in mechanical properties and the change in extent of reaction were followed simultaneously; it was found that no further development of mechanical properties occurred when the curing reaction between COOH and epoxide groups had ceased.
Ionic graft copolymerization. VII. Ionic graft copolymerization of β‐propiolactone onto the trunk polymers containing pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups
Authors: Shiota Tetsuya , Hayashi Koichiro , Okamura Seizo
Published: April 2003

The graft copolymerization of β‐propiolactone (βPL) onto the various trunk polymers containing polar substituents such as pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups was carried out. In the grafting onto the basic trunk polymer containing 4‐vinylpyriding units, two kinds of grafting mechanism are supposed. In the case of rigorously dried trunk polymer, the polymerization is initiated by betaine and proceeds with higher grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency in the presence of some amount of water. With acidic trunk polymer containing sulfonyl chloride groups, no graft copolymer was produced. The grafting efficiency of βPL onto the amphoteric trunk polymer containing acrylamide units was found to be between those of basic and acidic trunk polymer. In addition, the grafting by means of ionic copolymerization of βPL with maleic anhydride units contained in trunk polymer proceeded with very high grafting efficiency.
X‐ray studies on cellophane1
Authors: Venkateswaran A.
Published: April 2003

X‐Ray diffractograms of cellophane showed a considerable variation in the intensity corresponding to the 101, 101, and 002 planes. Applications of generally accepted procedures for estimating crystalline content in cellulosic materials yields varying results for crystallimity in cellophane. It is concluded that such procedures are not applicable to cellophane used in this study.
Voids as a source of haze in weathered poly(2,2,4,4‐tetramethyl‐1,3‐cyclobutylene carbonate)
Authors: Niegisch W. D.
Published: April 2003

Long‐term weathering studies of the subject transparent thermoplastic polymer revealed that sheets extruded from pristine resine gradually became hazy. Electron microscopy of fracture surfaces showed that minute voids were created during outdoor exposure. By the application of the Mie light scattering theory, it was possible to calculate that the average void size was 4 × 103 Å and that the concentration of voids numbered about 106/mm3. Yet the total void volume of the poorest sample, which had a haze value of 26%, was less than 0.05%. The average void size decreased over a three‐year period, but the concentration increased with exposure. A mechanism of void formation was formulated based on photo‐induced moleculàr degradation. Chemical evidence suggests that molecular degradation occurs by complete unzippering of a molecule, resulting in the formation of carbon dioxide and 2,2,4‐trimethylpentene‐3‐al. The aldehyde is believed to plasticize the polymer in the vicinity of a growing void and the carbon dioxide acts as a blowing agent, therby generating a void. Simultaneously, free radicals formed during molecular decomposition initiate further degradation of neighboring molecules. The propensity of this resin to haze can be effectively overcome by suitable cleanup and stabilization procedures.
Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene‐benzene system
Authors: Nisizawa M.
Published: April 2003

The method of stress relaxation has been used to study the effect of temperature on the stress decay behavior in the system of polyethylene–benzene. The behavior of stress decay in the polyethylene under benzene at various temperatures was observed and the activation energy of polyethylene–benzene system was obtained.
The study of polymers by high‐temperature ATR spectroscopy
Authors: Fujimoto K. , Wataya K.
Published: April 2003

A new high‐temperature attenuated total reflectance apparatus (HATR) was constructed and used at different temperatures for making infrared measurements on the same liquid or solid sample. It was found that this method was applicable to the continuous quantitative analysis of changes occurring during chemical reactions such as polymerization, isomerization, and crosslinking. In the bulk polymerization of styrene, the process of monomer consumption could be followed progressively. In the crosslinking reaction of high cis‐polybutadiene by sulfur‐accelerator or peroxide crosslinking systems, the decrease of cis content and its partial isomerization to trans structure was measured. Furthermore, in the crosslinking reaction of ethylene–propylene terpolymers (EPDM), the consumption of double bonds was observed over the course of the reaction with both sulfur‐accelerator and peroxide crosslinking systems. The effect was greatest in the case of methylenenorbornene‐type EPDM.
On the degree of crystallinity in jute and mesta fibers in different states of purifications and moisture conditions
Authors: Ray P. K.
Published: April 2003

The degree of crystallinity (DC) in different moisture conditions was studied for jute and mesta holo‐ and α‐celluloses. As in the case of raw fibers the DC was found to decrease as humidity increased, but the rate of change was diminished in the present case. The lower rate is explained on the supposition that some of the regions previously accessible to water have, after removal of lignin and hemicelluloses, assumed more ordered states and are less accessible. The DC increased as lignin and hemicelluloses were removed and tended to approach that of ramie or cotton. The crystalline structure of jute α‐celluloses was also found to be similar to that of ramie or cotton.
Cooking schedule of alkyd resin preparation. Part II. Effect of cooking schedule on molecular weight distribution of alkyd resin
Authors: Nagata Takumi
Published: April 2003

The effect of cooking schedule on the molecular weight distribution of an alkyd resin was investigated. At the molar ratio of 1.03/0.43/1.00 for glycerin, lauric acid, and phthalic anhydride, two kinds of alkyd resin were prepared, one by maintaining the reaction temperature at 170°C for an hour and then raising it up to 230°C (sample I), the other by raising the temperature up to 230°C at a uniform rate of 33°C per 10 min. (Sample II). Sample I and sample II were fractionated into seven or eight fractions by adding n‐heptane to 5 wt‐% toluene solution at 30°C. Acid valued, hydroxyl value, intrinsic viscosity [η], and the number‐averagè molecular weight M̄n were determined. The result showed that the molecular weight distribution curve obtained from sample I was much narrower than that from sample II. In addition, a relation was found between [η] and M̄n conforming to the equation [η] = KMα, where different values of K and α were obtained for sample I and sample II. Based on the differences in the molecular weight distribution curves and in the rate constants for the esterification reactions, glycerin/lauric acid and glycerin/phthalic anhydride at 170°C and 230°C, the mechanism of condensation reaction of short oil alkyd resin was discussed.
Compression creep behavior of a highly crosslinked plasticized polyester system
Authors: Steg I. , Katz D.
Published: April 2003

The influence of plasticizer addition on behavior of highly crosslinked unsaturated polyester–styrene systems was investigated by measurement of their compression creep and creep recovery at different temperatures. The correction between the observed behavior of the investigated polymeric systems and their structures was explained by assuming the presence of supermolecular structures which change in the applied field of stress at different temperatures. In a wide temperature range the plasticiezr addition shows a similar effect to that of temperature increase on creep recovery of the investigated polymers.
Rates of crystallization of copolyamides. I. Random copolymers of nylons 6 and 11
Authors: Hybart F. J. , Pepper B.
Published: April 2003

Rates and extents of crystallization of nylon 11 and nylon 6/11 copolymers have been measured by dilatometry. As the amount of copolymerization increased there was a decrease in the extent of crystallization and in the rates of crystallization for any degree of supercooling below the melt.
Grafting of acrylonitrile onto cellulose initiated by ceric ion
Authors: Rao S. Ranga , Kapur S. L.
Published: April 2003

Acrylonitrile was grafted onto cellulose with the use of ceric salt as initiator and the grafting was found to be maximum at 0.6N acid concentration. The effect of monomer and initiator concentration on the extent of grafting was studied. A new method for quantitative estimation of extent of grafting on cellulose was developed and its validity was established. The grafted samples with 20% increase in weight were found to be highly resistant to microorganisms.
Direct preparation of porous polyethylene filters by radiation polymerization of ethylene
Authors: Okada Minoru , Takehisa Masaaki , Machi Sueo , Danno Akibumi
Published: April 2003

In order to prepare porous, macroscopically homogeneous filters without a separate packing process, ethylene was polymerized by radiation in glass tubes. The bulk density of the polyethylene is approximately proportional to ρ(ƒM)2I0.9t2, where ρM is average ethylene density, ƒM is average ethylene fugacity, I is radiation dose rate, and t is reaction time. The effect of the bulk density on “treatment capacity” was investigated by experiments where air samples containing 0.1 wt‐% iodine vapor were filtered. Treatment capacity is difined as that amount of air per gram of polyethylene which passes through a filter until the polyethylene reaches the break point. The treatment capacity is approximately constant at 9 × 102 cm3/g over the bulk density range from 0.03 to 0.07 g/cm3, and it is lower at the outside of this range. The pressure drop due to the polyethylene filters varies with the 2.7th power of the bulk density when the bulk density is more than 0.03 g/cm3; below 0.03 g/cm3 this exponent increases with decreasing bulk density. Because of both the necessity of high Treatment capacity and that of low pressure drop, the optimum bulk density of polyethylene in the filter is about 0.03 g/cm3.
Studies in disperse dye transfer mechanism in polyester–viscose union at elevated temperatures
Authors: Kangle P. J.
Published: April 2003

The thermofixation process of dyeing polyethylene terephthalate–viscose union fabric with disperse dyes has been experimentally studied with a view to understanding the phenomena of dyeing polyester blends. It is shown how the distribution of a disperse dyestuff changes on the terylene and viscose portions of a union during different stages of dyeing by the thermofixation process. Equilibrium adsorption isotherm and rate curves of adsorption of disperse dyes on the polyester portion of the union have been determined. The nature of staining of the viscose portion of the union with different disperse dyes has been investigated. From the presented typical data it is possible to deduce fairly simple semiempirical rules regarding the phenomena of the thermofixation process of dyeing polyester–viscose union. It is pointed out that it is not possible to derive an exact thermodynamic theory to explain the data and describe the molecular mechanisms in such systems.
Effect of oxygen on intensity exponents of radiation‐induced polymerization rates
Authors: Tsurugi Jitsuo , Fukumoto Tsugio , Yamagami Masayuki
Published: April 2003

Gamma radiation‐induced graft polymerization to natural rubber in benzene solution (solution grafting), graft polymerization to natural rubber latex (Emulsion grafting), and emulsion polymerization of three vinyl monomers—styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN), were carried out under air atmosphere to compare the radiation intensity exponent of each polymerization rate under air atmosphere with that under nitrogen atmosphere or under vacuum. The intensity exponents of the solution grafting both under air atmosphere and under exclusion of air were found to be numerals near one half. This indicates prevailing normal radical mechanism. However, the intensity exponents of the emulsion grafting under air atmosphere were found to be 0.94, 1.00, and 0.82 for St, MMA, and AN, respectively, and those of the emulsion polymerization under air atmosphere, 0.16 and 0.15 for St and MMA, respectively, although those of both emulsion grafting and emulsion polymerization under exclusion of air were found to be numerals near to one half except for that of emulsion polymerization of AN. For emulsion grafting, the initiating species is considered to be trunk polymer radical but the terminating species is assumed to be the radical(s) produced in the water phase in the presence of oxygen. For emulsion polymerization, both initiating and terminating species are assumed to be the radical(s) produced in the water phase in the presence of oxygen.
The influence of intermolecular hydrogen bonding on the flow behavior of polymer melts
Authors: Blyler L. L. , Haas T. W.
Published: April 2003

The influence of hydrogen bonding on the flow behavior of polymer melts at high shear rate has been investigated using a capillary extrusion rheometer. The systems studied were copolymers of ethylene and acrylic or methacrylic acid. Hydrogen bonding was found to substantially enhance both flow activation energy and viscosity level, as well as the degree of dependence of viscosity on rate of shear. It was also found that hydrogen bonding does not influence the critical shear stress for onset of “melt fracture.” The data support the view that hydrogen bonds act effectively as temporary (quasi‐) crosslinks during the short time scales of deformation involved in flow at high shear rates.
Abrasion resistance of pre‐stressed and stressed rubber vulcanizates
Authors: Lambert D. H. , Boonstra B. B.
Published: April 2003

The abrasion resistance of carbon black‐reinforced SBR‐1500 vulcanizates has been shown to be drastically reduced by the application of tensile strain during the abrasion process. Pre‐stressing of similar vulcanizates, however, has no effect upon the abrasion resistance.
The analysis of polyurethane foams II. Chemical constitution of the polymer
Authors: Dawson B. , Hopkins S. , Sewell P. R.
Published: April 2003

Efforts have been made to establish the chemical constitution of water‐blown polyurethane foams. Specific reagents have been used to indicate the presence of biuret or allophanate linkages. Partial hydrolysis techniques have been used to degrade foams selectively and hence isolate parts of the chain network. These methods yield information which is not satisfactorily obtained from the examination of undegraded polymer and which is not available after total degradation. It has been shown that polyureatype linkages are present in the chain network of both polyester and polyether foams.
Glass‐rubber transition behavior and compatibility of polymer pairs: Poly(ethyl acrylate) and poly(methyl methacrylate)
Authors: Sperling L. H. , Taylor D. W. , Kirkpatrick M. L. , George H. F. , Bardman D. R.
Published: April 2003

A series of interpenetrating polymer networks were prepared containing PMMA and PEA as their two components. Corresponding telomer mixtures and random copolymers were also prepared for comparison purposes. The glass‐rubber transition studies were made via shear modulus and dilatometric measurements. The results indicate one very broad transition for the IPN's rather than two transitions expected for incompatible polymer pairs. An interpretation based on the compatibility or near‐compatibility of the PEA/PMMA pair is offered.
Some rheological properties of molten polytetrafluoroethylene
Authors: Ajroldi G. , Garbuglio C. , Ragazzini M.
Published: April 2003

Measurements of melt viscosity on samples of polytetrafluoroethylene of different molecular weight were carried out at 360°C by means of tensile creep tests in the linear viscoelasticity range. The apparent activation energy for viscous flow in the range between 330° and 380°C was estimated to be 20 kcal/mole. A value of about 7,500 was also determined for the average molecular weight between entanglement points (Me), from the equilibrium compliance (De). Melt viscosity data were compared with zero strength time (ZST) values and a linear correlation was found on a bilogarithmic scale. The dependence of ZST on the applied stress and temperature was also studied and the results are discussed on the basis of Bueche's theory on the creep at rupture above the glass transition temperature.
Amorphous state transitions in butadiene–acrylonitrile copolymers
Authors: Geiszler W. A. , Koutsky J. A. , Dibenedetto A. T.
Published: April 2003

Differential thermal analysis, creep measurements, and gas permeation rates are used to confirm the existence of a transition zone in three butadiene acrylonitrile copolymers in a temperature region that starts at roughly 15° to 25°C above the main glass transition temperatures of the copolymers and extends over a broad temperature range. The change appears to be slightly endothermic and softens the copolymers upon heating. It is speculated that the copolymers are in a mesomorphic state above their main glass temperature in which there is either a degree of ordering or a low‐grade crystallinity of polybutadiene units along the copolymer chains. It is not until the copolymers are 50° to 75°C above their main glass temperature that they become truly amorphous.
Distribution of internal flaws in acrylic fibers
Authors: Thorne D. J.
Published: April 2003

Optical microscopy has been used to illustrate various types of discontinuities, or flaws found within acrylic polymer fibers and to determine the distribution of such internal flaws along the length of the fiber. Flaws are comprised of particulate inclusions and voids. The internal flaw distributions approximate a Poisson type for point flaws, but significant variation is found in mean flaw concentrations from 0.03 to 2.3 flaws/mm. Both flaw concentration and flaw‐free length distributions have been used to predict, for random selection of test lengths, the probability of avoiding a flaw with respect to gauge length (P versus Lg plots).
The thermal stabilization of polyethylene sulfide
Authors: Lee T. C. P. , Wragg R. T.
Published: April 2003

It has been shown that the resistance of certain polyethylene sulfides to thermal degradation can be markedly improved by the addition of small amounts of metal dithiocarbamates, thioureas, or diphenyl acetylene together with a suitable carbodiimide. The extent of degradation, as indicated by the concurrent changes in polymer melt viscosity in the temperature range 220°–250°C, was dramatically reduced, in particular, by a stabilizer comprised of 4% hexamethylenebis(tert‐butyl)carbodiimide and 2% diphenylacetylene. At 250°C polyethylene sulfide (Dabco initiated) was stable in the melt viscometer for a period of 8–10 min and the resulting extrudate showed little sign of discoloration. The detailed mechanism of stabilizer action cannot be put forward at this stage because of uncertainty regarding the mode of polymer degradation which could occur by radical or ionic processes.
Photodegradation of nylon 66. I. Phototendering by TiO2
Authors: Taylor H. A. , Tincher W. C. , Hamner W. F.
Published: April 2003

The mechanism by which TiO2 exerts a phototendering effect on nylon 66 photodegradation has not been previously explained. To aid in the elucidation of this mechanism, the wavelength dependence curves of photodegradation of nylon 66 both with and without TiO2 have been accurately determined. These data, in conjunction with reflectance and phosphorescence measurements, indicate that the phototendering effect of TiO2 proceeds by a chemical rather than an energy transfer mechanism.
Properties of PVC. II. Properties of PVC compounds with solvents
Authors: Maláč J. , Altmann V. , Zelinger J.
Published: April 2003

It was the aim of this paper to study the influence of the solvent residues in PVC compounds on physical and mechanical properties of samples prepared from them as well as the rheologic properties of their melts. Besides tetrahydrofuran other solvents are also partly retained in PVC even after processing at higher temperatures. The properties of samples prepared from PVC compounds containing solvents depend on the solubility parameter of the solvent used. Solvents with a solubility close to that of PVC have the same effect as plasticizers. Solvents with very high solubility parameters, e.g., water, influence the flow and dynamic properties in just the opposite way than plasticizers and behave rather like fillers. A mechanism for influencing the properties of PVC by the presence of solvent residues is suggested.
The effect of phenol/formaldehyde ratio on the char yield from phenolic resins
Authors: Mitchell S. J. , Pickering R. S. , Thomas C. R.
Published: April 2003

An idealized mechanism for the carbonization of phenolic resins was adopted and an equation was derived for the char yield. In simplified cases this was shown to be a function giving a maximum of 67.9% at a 1:1 formaldehyde/phenol molar ratio, falling rapidly at lower and slowly at higher ratios. In experimental verification, the alkalicatalyzed reaction of phenol and formaldehyde at various molar ratios was studied and the resulting resins were characterized and carbonized. The char yields were found to correspond well with predictions, with a maximum of about 67.2% in the region of 1.1:1 formaldehyde/phenol molar ratio.
Degradation du polychlorure de vinyle preparé en presence de composes organoaluminiques
Authors: Guyot A. , Rocaniere P. , Bert M.
Published: April 2003

Les alkylaluminium en milieu CCl4 provoquent, avec un faible rendement, la polymérisation du chlorure de vinyle et réagissent sur le polymère formé. Une réaction rapide se produit après une période d'induction de 2 heures environ, qui forme un bon catalyseur de deshydrochloruration du polymère. En l'absence de monomére, les alkylaluminum peuvent attaquer le polychlorure de vinyle, et la réaction rapide, pas toujours observée, peut ètre catalysée par les parois du réacteur. Les polymères attaqués présentent une très mauvaises tabilité thermique. Les polymères préparés avec un systéme alkylaluminum–titanate de butyle ne sont que fort peu attaqués par l'alkylaluminum et leur stabilité thermique est relativement bonne. Les résidus de titanate, lorsque leur teneur dépasse 100 ppm, inhibent l'accélération de la dégradation thermique.