bluuebunny/crossref_metadata_2025 huggingface dataset:
Terpolymers. II. Mechanical properties and transition temperatures of terpolymers of vinyl stearate, vinyl acetate, and vinyl chloride
Authors: Jordan Edmund F. , Artymyshyn Bohdan , Riser George R. , Nidock Jonathan , Wrigley A. N.
Published: April 2003

Vinyl stearate was studied as a major internal plasticizer in terpolymers containing vinyl acetate and vinyl chloride. The terpolymers were prepared by systematically replacing vinyl acetate by close increments of vinyl stearate starting with combinations of vinyl acetate and vinyl chloride, in increments, over all compositions. For comparison of properties, a complete range of copolymers of vinyl stearate and vinyl chloride, as well as mixtures of poly(vinyl chloride) and di‐2‐ethylhexyl phthalate (DOP) were also made. The external plasticizer was more efficient in reducing the glass temperature than was vinyl stearate. The decline in Tg with weight fraction of plasticizer was linear for the copolymers and terpolymers but concave downward with the liquid diluent. The linear decline was shown to involve mere additivity of the free volume contributed by each side‐chain methylene (or methyl) group in both vinyl esters to reducing Tg. The mechanism of the diluent system was more complex. However, the magnitude of the reduction of tensile modulus at a given weight fraction of DOP could be equaled or exceeded by the same amount of vinyl stearate, by increasing the vinyl acetate content of the base copolymer to 40 mole‐% or more. Unfortunately, the ultimate strengths and elongations of internally plasticized systems were reduced more than those of the mixtures at comparable compositions. Vinyl stearate was found to markedly retard photolytic degradation compared to both vinyl acetate and the external plasticizer in unstabilized samples having nearly the same thermal treatment. The effect was greater than could be ascribed to dilution by the long alkyl group. The production of a stearoyl radical more stable than the radicals initiating dehydrochlorination is suggested as a possible mechanism.
Evaluation of steady‐state flow curves from model molecular weight distributions
Authors: Cote J. A. , Shida M.
Published: April 2003

Graessley's theory of entanglement was applied to several model distributions. The distribution functions chosen were such that the differential weight distributions were triangular with respect to a log molecular weight axis. The molecular weight level, breadth of the molecular weight distribution, skewness, and blending of simple distributions were studied in their effect on the steady‐state flow curve. The governing factor for the shape of the reduced flow curve was shown to be M̄z+1·M̄z/M̄w2. Other general features of the flow curve predicted by Graessley's theory were discussed.
Studies on biaxial stretching of polypropylene film. IX. Melting behavior of biaxially stretched film in one step
Authors: Tanaka Hiroshi , Masuko Toru , Okajima Saburo
Published: April 2003

Melting temperature of a film biaxially stretched in one step in air at 152 or 140°C increases with increase of vA, whereas heat of fusion and density decrease with increase of vA, where vA is the degree of stretching in area. The rapid decrease in density occurs for vA > 10. Extrapolation of the plot of the density versus vA−1/2 gives a value of 0.870 g/cm3 at infinite vA, which has been reported as the amorphous density of isotactic polypropylene by Farrow. This is so because the fine structure of the film becomes more and more amorphous with further stretching and reaches completely amorphous state at infinite vA. The temperature of stretching has a strong effect on the thermal behavior of a film; a low stretching temperature (140°C) brings about lower melting temperature, heat of fusion, and density. Crystallinity after melt press has not so large an effect on the melting behavior as the stretching temperature. Melting temperature and the shape of the thermogram also depend on the heating rate. There is an appropriate heating rate depending on vA which gives the minimum melting temperature. With stretched samples, a small side peak or a shoulder appears at a relatively low temperature in the thermogram when a high heating rate is used.
Studies in chemically modified celluloses. V. Affinities of vat dyes for chemically modified celluloses
Authors: Shenai V. A. , Veeramani M.
Published: April 2003

Cotton cellulose was separately oxidized by potassium metaperiodate, potassium dichromate–sulfuric acid, and potassium dichromate–oxalic acid at two oxidation levels, and the resulting oxycelluloses were further modified by treatment with chlorous acid and sodium borohydride in order to prepare a series of chemically modified celluloses with different functional groups. These fiber substances were dyed with leuco‐flavanthrone at 40°C for different periods till equilibrium was reached. Adsorption isotherms were obtained with three purified vat dyes, and thermodynamic affinity of the dyes for the modified celluloses was determined, taking into consideration the adsorption of hydroxyl ions by cellulosic material and of sodium ions by carboxylate groups of oxycellulose. The presence of aldehyde and carboxyl groups is shown to decrease the rate of dyeing as well as the affinity of the dyes.
A method of calculating densities of polymers
Authors: Sewell J. H.
Published: April 2003

Molar volumes of substantially amorphous polymers may be calculated by using additive constants derived from constitutive atomic and structural parachor contributions. For 34 polymers, ranging in density from 0.83 to 2.03 g/cm3, the greatest error in the calculated molar volume compared with the measured value was 13.9%, while for 30 of the polymers the error was less than ±7%, with a mean error of ±3.9%.
Sorption of vapors in cellulose film
Authors: Dollimore D. , Holt B.
Published: April 2003

The rates of sorption of water vapor and of methanol vapor in cellulose film were examined by stepwise increments of vapor pressure. In addition, the rates of sorption of the series of vapors water, methanol, ethanol, n‐propanol, and n‐butanol were studied at pressures just below the respective saturated vapor pressures. The results obtained from both parts of the study are explained in terms of a bimodal diffusion mechanism. This consists of the simultaneous diffusion of vapor into the microporous structure of the cellulose film and diffusion from the micropores into the polymer matrix.
The chemistry of fast‐curing phenolic adhesives. I
Authors: Tiedeman G. T. , Sanclemente M. R.
Published: April 2003

Certain low molecular weight, resinous polymers, such as those derived from phenol and formaldehyde, may be chemically modified with aromatic amines to produce other resins of physical properties similar to those of the original resins, but with chemical reactivity which is orders of magnitude faster than that of the unmodified resins. This means that while an ordinary phenolic adhesive cures in minutes at high temperature, a properly modified phenolic can be advanced in seconds at ambient conditions to a cured resin of strength and durability comparable to those of ordinary phenolic adhesives.
Coatings for plastics. Dispersions of clean metal particles in polymer matrices
Authors: Lupinski J. H.
Published: April 2003

Oxides are frequently used to improve the mechanical properties of plastics. Here we report how oxides of zinc, lead, cadmium, and indium, when embedded in a polymer matrix, can be electrochemically reduced, resulting in a polymer‐metal “composite” of high electrical conductivity. This method of preparation provides a uniform dispersion of small, clean metal particles, not obtainable by blending metal powder and polymer. The “composites” are somewhat porous, and other metals can be deposited on the “composites” from either electroplating or electroless plating solutions.
Fracture studies in rubber‐modified acrylics. I. Experimental method: Design of sandwich‐tapered double‐cantilever beam cleavage specimens
Authors: Kobayashi T. , Broutman L. J.
Published: April 2003

Double‐cantilever beam cleavage specimens are very useful in characterizing the fracture behavior of isotropic, homogeneous, brittle, and semibrittle polymers. However, until this time they have not been used for ductile materials such as rubber‐modified polymers or polycarbonates because of excessive yielding or breakage of the specimen arms before crack propagation can occur. In order to make it possible to measure the fracture surface work of these materials, a new sandwich cleavage specimen was developed by bonding rigid reinforcement plates to both sides of the specimen sheet. With this sandwich‐tapered double‐cantilever beam cleavage specimen, one can create conditions under which controlled crack propagation through tough ductile materials and measurement of the fracture surface work–two previously unobtainable results–are readily determined. In this paper, the design and construction of the sandwich specimens, test procedure, and the data analysis will be discussed in detail.
Effect of various triazine derivatives on the thermal oxidative degradation of isotactic polypropylene
Authors: Osawa Zenjiro , Seng Ng Mok , Ogiwara Yoshitaka , Oto Yukio , Matsui Koji
Published: April 2003

A number of triazine derivatives, mostly aryloxy‐s‐triazines, were prepared, and the effects of these compounds on the thermal oxidative degradation of isotactic polypropylene were examined by conventional oxygen uptake. Almost all triazine derivatives prepared showed a more or less inhibitive effect on the degradation of the polymer. Among them, α‐ and β‐napthyloxy‐s‐triazines were found to be excellent inhibitors. On the basis of the results obtained, the relationship between inhibitive effect and the structure of the triazine derivatives is discussed.
Wool graft copolymers initiated by azobisisobutyronitrile
Authors: Bendak A. , Hebeish A.
Published: April 2003

Grafting of methyl methacrylate onto wool fibers using azobisisobutyronitrile as initiator has been investigated under a variety of conditions. Increasing the monomer concentration caused a significant increase in the graft yields. The same holds good for initiator concentration and reaction time, but to a lower degree. The grafting reaction was favorably influenced considerably by the nature of solvent used; it follows the order methanol > dimethylformamide > benzene. For practical significance, a mixture of water:methanol:DMF (75:24:1) was found to be the most effective medium for grafting. Presence of lithium chloride in the polymerization system favors grafting during the later stages of reaction, whereas presence of ceric sulfate was effective for higher grafting in the initial stages of reaction. Reduction of wool prior to grafting enhanced its ability to grafting; the latter increases in proportion to the thiol content. The opposite holds true for acetylation. Alkali solubility measurements reveal that an interaction between wool and methyl methacrylate in presence of AIBN took place.
Investigation of the dependence of the properties of the phenoplasts of phenolaniline–formaldehyde resol resin on the degree of kaolin filling and on their physical structure
Authors: Bozveliev L. G. , Kabaivanov V. S.
Published: April 2003

An investigation was made of the dependence of 13 types of standard physical and mechanical and electric insulation properties of phenoplasts of phenolaniline–formaldehyde resol resin on their filler content in a broad range of 14 to 47 vol‐%. It is found that the respective curves have more than one maximum and periodically pass through several maximums and minimums. The periodicity is more clearly seen in the curves reflecting the dependences of the properties on the calculated mean thickness of the resin adsorption coating on the filler particles. With these curves the extremal values appear over more or less even intervals of the adsorption coating thickness. The periodicity relating to the change in this thickness is explained by the periodic formation of particles of a new type of filler in the points of a whole number of monoglobular adsorption coatings, and of a maximum amount of globules oriented toward them in the points of a whole number and a half monoglobular adsorption layer. The periodical appearance of an oriented (regarding the particles) globular layer determines the appearance of periodical positive and negative orientation effects in the properties of the phenoplasts. The diagram we propose is confirmed by the regular periodical change in the various properties as well as by the measured ratios of the mean thicknesses of the adsorption coating in the points of the extremums of the various types of curves, determined by the differential curves method.
The market for polyester, nylon, and rayon yarns in tire applications
Authors: Promislow A. L. , Steele R. , Whitworth P. D.
Published: April 2003

The use of rayon, nylon, and polyester in various tire applications is described, and the relative merits of each are defined. Future development objectives and expectations are outlined. Volume projections for polyester, nylon, and rayon in tire reinforcement are given as a function of tire type. Product life cycles of tire reinforcement materials are analyzed in terms of market share. Polyester is expected to become dominant in 1973.
Fiber properties required for tires
Authors: Snyder Robert H.
Published: April 2003

Contrary to what the appearances would suggest, a pneumatic tire is basically an engineered textile object rather than a rubber one. The functional characteristics and performance of tires are chiefly determined by the properties of the textile fibers and by the way in which they are disposed in the tire structure. The specific roles of some of these properties (e.g., modulus, tensile strength, fatigue resistance, hysteresis) will be related to tire performance. Different tire constructions require a different balance of textile properties for optimum performance. Belted tires, and especially radial ply tires, present a different set of requirements for optimum textile fiber performance in tires. The nature of the differences are discussed.
Fiber glass—its future in belted tires
Authors: Kerivan Alan R.
Published: April 2003

The rapid success of fiber glass‐belted tires (from very low production in 1966 to one hundred million units in 1971) is discussed in terms of specific cord properties. The inherent glass characteristics of high modulus, high tensile strength, and low elongation are shown to be ideal for belted tires. Applications of fiber glass for belts of light commercial and heavy‐duty tires are discussed. The opportunity for developing new fiber glass cords which offer improved cost/performance characteristics are explored, including cord geometry and fiber diameter. The cost/performance capabilities of fiber glass for use in radial tires, both in the belt and in the carcass, are discussed as additional future opportunities. Laboratory and road test information is detailed and outlined. Ride aesthetics of the all‐glass radial tire design is emphasized. The market penetration for fiber glass tire cord will be projected through 1980.
Current inorganic fibers for tires: Steel
Authors: De Bruyne E. A. , Vanhoutte J. S.
Published: April 2003

An outline covering the evolution of the more popular tire‐reinforcing materials from 1960 to 1970 is presented. Technical and economic factors pro/con steel tire cord for that period are reviewed. Using the past period as a base, the present and future prospects for steel tire cord are analyzed. Comments on the present properties of steel tire cord in relationship to tire requirements are given. In addition, desirable and expected product improvements are covered with special emphasis on achievable product development.
Future organic tire fibers
Authors: Wilfong Robert E. , Zimmerman Joseph
Published: April 2003

In the history of the automobile, organic fibers have dominated the tire reinforcement field, starting with cotton and progressing through a series of man‐made fibers, each finding its place on the basis of its special attributes and overall performance. In general, these fibers were engineered for textile applications, but were subsequently adapted by special processing to make them as suitable for tires as possible. However, each has had limitations which have kept it from certain segments of the market. Moreover, the performance demands on tires have become progressively more stringent, and new tire designs have evolved, so that new tire reinforcement materials are needed. While glass and steel wire are contributing some of the desired properties, they also have their limitations. On the other hand, the potential for creating new, more favorable property balances from organic fibers is far from exhausted. This paper will discuss the main tire yarn property criteria and the polymer and fiber structural factors which control them. Then, the properties and performance of an entirely new fiber, specifically engineered chemically and physically for tire reinforcement, will be described. Fiber properties discussed will include tensile strength, modulus, dimensional stability, fatigue resistance, adhesion, and thermal stability.
Fracture studies in rubber‐modified polymers. II. Experimental results: Fracture surface work of rubber‐modified acrylics
Authors: Kobayashi T. , Broutman L. J.
Published: April 2003

With the use of a sandwich‐tapered double‐cantilever beam cleavage specimen (described in part I of this series), the fracture surface work of several commercial and experimental acrylic multipolymers has been measured as a function of crack velocity and rubber content. The plots of fracture surface work versus crack velocity clearly exhibit the effects of rate (crack velocity) and rubber concentration on fracture behavior. Specifically, the fracture surface work of specimens with seven different rubber contents has been determined over a crack velocity range from 10−5 meters/sec to approximately 10 meters/sec. For each material, distinct maxima occur in the curves of fracture surface work versus crack velocity. The significance of these observations is discussed.
Thermomechanical behavior of a systematic series of poly(L‐alpha‐alkylamino acids) in dry and moist nitrogen
Authors: Krug R. R. , Gillham J. K.
Published: April 2003

The solid‐state thermomechanical behavior of polyglycine, poly‐L‐alanine, poly‐L‐valine, and poly‐L‐leucine was investigated throughout the temperature range −180° to 500°C in dry and moist nitrogen atmospheres at about 1 cps using torsional braid analysis. Transitions of the dry polymers and complexities introduced by the presence of water were investigated by temperature cycling.
Gel permeation chromatography: Differential operation
Authors: Chuang Jau‐Yi , Johnson Julian F.
Published: April 2003

Operation of gel permeation chromatographs in the differential mode provides a sensitive method for detecting small differences in molecular weight distribution between similar samples. The solvent used in this case is a dilute solution of the reference polymer in an organic solvent. This solution is used in both the reference and the separation column. Samples of the material to be compared are injected in the normal manner. Only differences between the samples are reflected in the resulting chromatogram. For process control, this offers a simplified data presentation and should lead to easier detection of changes in operating conditions.
High‐temperature elastomers: A systematic series of linear poly(carborane‐siloxane)s containing icosahedral (CB10H10C) cages. I. Thermomechanical behavior in nitrogen
Authors: Roller M. B. , Gillham J. K.
Published: April 2003

An extensive study of structure–bulk property relations for a systematic series of well‐defined linear poly(carborane‐siloxane)s is reported. These polymers form the backbone components of the most recently developed high‐temperature elastomers. The basic structure is
magnified image
where (1) x = 1, 3, 4, 5, ∞; (2) A = endgroups (reactive and inert); (3) Z = meta‐, para‐carborane (for x = 3); (4) R = CH3, R = C2H4CF3 (for x = 3), one in five R = C6H5 with the remainder ∼CH3 (for x = 4, randomly and regularly substituted); (5) molecular weight = ∼10,000, ∼50,000 (for x = 3). Thermomechanical spectra (∼1 cps) from −180°C to 625°C to −180°C in nitrogen at 3.6°C/min and thermogravimetric data from 25°C to 800°C in argon are presented. Physical transitions (Tg, Tm, Tcrys, Tsec) are discussed, including a correlation of Tg data with structure (for x = 1, 2, 3, 4, 5, ∞) using a copolymer equation. Thermostability is also discussed in terms of structure.
Low‐angle x‐ray scattering investigation of untreated and alkali‐treated jute
Authors: Sahu N. C. , Mishra D.
Published: April 2003

Pore analysis of untreated and alkali‐treated samples of jute by the low‐angle x‐ray scattering method was made. The measurements were made using the low‐angle scattering camera of the latest design by Kratky.1 The theories of Kratky2–4 and Porod5–7 were used to evaluate and compare the various parameters of the scattering particles present in both types of jute fibers. Babinet's8 reciprocal principle of scattering in optics was taken into account.
Mechanism of yield and fracture in ABS materials
Authors: Hagerman Edward M.
Published: April 2003

Four commercial grades of ABS of varying physicomechanical properties were fractured in tension at three straining rates. Photomicrographs of the fracture surfaces were used to qualitatively describe the effects of straining rate on craze growth. Based on a micrograph of what is assumed to be the first stress‐activated state of craze formation, a model describing the function of the elastomer phase in these materials is presented.
A method for determining the optimum peroxide‐to‐amine ratio for self‐curing resins
Authors: Bowen R. L. , Argentar H.
Published: April 2003

The rate of polymerization of a methacrylate monomer was influenced by the molar ratio of benzoyl peroxide to an aromatic tertiary amine accelerator when the product of the concentrations of these was kept constant. The maximum rate, measured as the minimum gel time, occurred in monomer solutions containing about 1.5 moles of peroxide per mole of amine.
Polyesters from bisacid A2. Electrical properties of glass fiber laminates
Authors: Lenk R. S.
Published: April 2003

The preparation and purification of bisacid A2, the preparation of crosslinkable polyesters from bisacid A2, and some of the properties of the resulting resins and laminates have been reported in earlier communications.1–7 This paper reports the surface and volume resistivities of laminates according to B.S. 2782 as well as their dielectric loss and permittivity at 23°C over a frequency range of about 9 decades and discusses the significance of the results.
Water binding and irreversible dehydration processes in cellulose acetate membranes
Authors: Frommer Moshe A. , Shporer Mordechai , Messalem Rami M.
Published: April 2003

The relative amounts of freezing and nonfreezing water in various water‐wet cellulose acetate (CA) membranes were determined by NMR techniques, from the initial heights of the water component in the free induction decay (MNR intensity). The results suggest that (1) a significant fraction of the water in various wet CA membranes does not freeze, probably because of strong interaction with the polymer; (2) the relaxation times T2 of the nonfreezing water are of the order of milliseconds indicating that they are still highly mobile compared with ice; (3) all the water contained in dense CA films or in membranes equilibrated at relative humidity of 0.93 does not freeze upon cooling the membranes from room temperature to −60°C; (4) the amounts of nonfreezing bound water in membranes is higher than the total amount of water absorbed from liquid water by a dense film of the same polymer. However, the amounts of nonfreezing water in various CA membranes as calculated from the “relative NMR intensities” is substantially lower than those calculated from DSC melting endotherms by assuming the heat of fusion of water in membranes to be identical to that of pure water. Various possible reasons for this discrepancy are discussed. Measurements on the first desorption‐adsorption cycle of wet CA membranes have also been performed. They suggest that during the first dehydration process, irreversible changes are induced in the structure of the membrane which result in a significantly lower accessibility of the polymer to interact with water. The extent of these irreversible changes in membrane structure is dependent on the details of the dehydration process being more pronounced at higher temperatures.
Preparation of the fine powdery copolymer of glycidyl methacrylate–divinylbenzene and its application as a pigment
Authors: Mizutani Yukio , Matsuoka Seishiro , Kusumoto Koshi
Published: April 2003

In order to prepare the functional and fine powdery polymer, glycidyl methacrylate (GMA) and divinylbenzene (DVB) were polymerized in cyclohexane. This polymerization was heterogeneous. In the time–conversion curve, an autoaccelerating phenomenon and an apparently steady state were observed, and the activation energies for both reactions in the earlier stage and the steady state were calculated to be 28 kcal/mole and 11 kcal/mole, respectively. It is especially noteworthy that the increase in the DVB concentration decreased the polymerization rate. The diffusion of the monomers through the polymer matrix should be one of the most important factors. Some properties of the copolymer and its application as a mordant were studied.
Preparation and physical properties of polybutadiene grafted onto silica
Authors: Yamashita Shinzo , Kohjiya Shinzo , Kita Atsushi , Shimizu Akihiko
Published: April 2003

Polybutadiene grafted to silica (PG) was prepared by the reaction of living polybutadiene with chlorinated silica. The graft efficiency was below 10%. PG and PG–commercial butadiene rubber blend were cured with sulfur. In either vulcanizate, the following phenomena were found as compared with the controlled samples: tensile modulus increased, degree of swelling and elongation lowered, and tensile strength unchanged. These results showed nearly the same tendency as had been found in the case of the rubber compounded with silica which was treated by coupling agents. In spite of a high tensile modulus of PG vulcanizate, it resulted in a lowering of the dynamic modulus compared with the controlled sample.
Studies of relaxation phenomena in polymers. III. Superimposed transition mechanisms in polyisobutylene and poly(vinyl acetate)
Authors: Jansson Jan‐Fredrik
Published: April 2003

Based on the general properties of the function log J2 = gα{log J1}, discussed in earlier papers,1,2 the existence of two superimposed dispersion mechanisms in the glass–rubber transition of polyisobutylene (PIB), and poly(vinyl acetate) (PVAc) is discussed. A simple weighting model is used for separation of the two mechanisms. For the interpretation of the β‐mechanism, in PIB, the following facts are taken into account: (a) The loss maximum of the β‐mechanism appears in a zone where only very reduced segment movements occur. (b) The methyl side groups in PIB require special conformations of the main chains before they can rotate. (c) The apparent activation energy for the β‐mechanism is approx. 20 kcal/mole. Thus, for PIB the following interpretations for the α‐ and β‐mechanisms are proposed: (1) The α‐mechanism is due to simple segment movements. (2) The β‐mechanism appearing in the “Tg region” is due to coupled movements between the main chain and methyl side groups. The ester groups of poly(vinyl acetate) need a lot more space for their rotations than the carboxy groups of poly(methyl acrylate) and can be expected to give considerable steric hindrance. It is therefore reasonable to suppose that a transition mechanism similar to the β‐mechanism of polymethacrylates will appear in the “freezing” region of poly(vinyl acetate). The analysis of the β‐mechanism is made using the same separation method as for polyisobutylene.
Prediction of molecular weight distribution of high‐density polyethylene made in a continuous reactor from fixed ethylene concentration batch reactor data
Authors: Hoff R. E. , Shida M.
Published: April 2003

The polydispersity index, Mw/Mn, of the product of an ideal continuous stirred tank reactor can be predicted from batch reactor data. A method for the prediction, in the case of high‐density polyethylene synthesis, comes from finding the effect of catalyst age upon yield, Mw, and Mn in a batch reactor operated at constant pressure. These catalyst age effects are combined with the catalyst age distribution in the continuous reactor, and integration over all ages gives the yield and the polydispersity index for the continuous reactor product. This scheme for prediction was applied to a particular catalyst system, and the calculated values have been found to agree with observations.
1‐Chloro‐1,3‐butadiene copolymers. I. Synthesis of copolymer with 1,3‐butadiene and physical properties of its vulcanizate
Authors: Yamashita Shinzo , Atomori Sei‐Ichi , Kohjiya Shinzo , Miyagawa Toshio
Published: April 2003

Emulsion copolymerization of 1‐chloro‐1,3‐butadiene and 1,3‐butadiene was carried out using potassium persulfate at 50°C. The thus synthesized 1‐chloro‐1,3‐butadiene copolymer was possible to be cured with 2‐mercaptoimidazoline (MI) as well as with sulfur. The tensile strength of the MI vulcanizate of the copolymer compounded with 30 phr HAF black reached 100 kg/cm2 and was higher than that of the sulfur vulcanizate. Moreover, these two vulcanizates showed higher tensile strengths than the sulfur vulcanizate of emulsion butadiene rubber. The addition of the copolymer to the blend of chloroprene rubber (Neoprene GRT) and butadiene rubber extremely improved the elongation and the tensile strength. Dynamic measurements of the vulcanizates showed that the glass transition temperature of the copolymer was situated at the region between that of butadiene rubber and that of chloroprene rubber.
Determination of optimal reactor system configuration for polymerization reactions. I. Free‐radical polymerization at constant temperature
Authors: Shastry J. S. , Fan L. T. , Erickson L. E.
Published: April 2003

A systematic procedure was developed for selecting the type of reactors or a reactor system configuration for polymerization reactions. Two different mechanisms were investigated, and the “best” reactor system to give the desired quality of the product was determined using a systems synthesis technique. The behavior of the system in the neighborhood of the optimal solution was explored, and the effect of variation in the rate constants and the initial concentrations of the catalyst and the monomer on the optimal reactor system was examined. Recycle streams were introduced and their effect on the system performance was investigated, and finally the applicability of the systems synthesis technique to other polymer reactor design problems was discussed.
Thermal behavior of nylon 6 copolyamides containing aromatic rings
Authors: Ajroldi G. , Stea G. , Mattiussi A. , Fumagalli M.
Published: April 2003

The thermal behavior of terpolymers of caprolactam (CL) and of hexamethylenediammonium isophthalate (IH) and terephthalate (TH) has been studied in a wide range of compositions by differential thermal analysis. It has been found that either amorphous or crystalline polymers having different crystallization rates can be obtained by changing the composition. The dependence of melting points and glass transition temperatures on the composition has been investigated. The dependence of Tg on the composition for the copolymers CL–IH, IH–TH, and CL–TH has been described by means of the Gordon‐Taylor equation. It has been found that this equation fits the experimental data for the IH–TH system only if a parameter which takes into account interactions between the monomeric units is introduced. A ternary iso‐Tg map has been obtained through statistical analysis. The influence of the chain stiffness and bulkiness of the monomers on the glass transition temperature is discussed.
Increase of gold–Teflon FEP joint strength by electron bombardment
Authors: Sessler G. M. , West J. E. , Ryan F. W. , Schonhorn H.
Published: April 2003

The strength of joints between Teflon FEP (Type A) and 500‐ to 1000‐Å gold layers deposited by evaporation can be greatly increased if the Teflon surface is subjected to electron‐beam bombardment prior to the evaporation process. Typically, joint strengths of about 60 kg/cm2, approaching the bulk strength of Teflon, are obtained for treatments with electron‐beam energies in the range of 5 to 20 keV and intercepted charge densities of about 5 X 10−6C/cm2. This compares with gold–Teflon joint strengths of about 10 kg/cm2for untreated material. The increase in joint strength is believed to be primarily due to crosslinking caused by the electron bombardment. Compared to the other known treatments to improve gold–Teflon joints, the present method has the advantage that the charge‐storage properties of the Teflon are not irreversibly degraded. It is possible, for example, to store charge densities up to 3 X 10−8C/cm2, on 25‐μm films treated with this method, with the same favorable charge‐retention properties and thermally stimulated current characteristics as obtained for untreated Teflon.
Radiation‐induced solid‐state polymerization in binary systems. VII. Polymerization in solid–liquid equilibrium phase containing long‐chain compounds
Authors: Kaetsu Isao , Ito Akihiko , Hayashi Koichiro
Published: April 2003

The radiation‐induced polymerization of binary systems consisting of vinyl monomers (mainly methyl methacrylate) and various long‐chain compounds in solid–liquid equilibrium state has been studied. Phase diagrams of these systems showed that all systems containing long‐chain compounds form a complete crystalline phase at temperatures below the solidus line. It was found that remarkable acceleration of the polymerization occurred in the solid–liquid equilibrium state. The long‐chain compounds are classified into three groups according to the acceleration effect. The group including paraffin, long‐chain esters, and cetyl alcohol exerted the largest acceleration effect over wide temperature regions at which the solid–liquid equilibrium exists. Maximum polymerization rate was observed at temperatures below the melting point in the presence of long‐chain compounds of the above‐mentioned group. It was observed in this case that the long‐chain compounds crystallized to form very fine colloidal particles and the system was soft and waxy in the solid–liquid equilibrium state. The acceleration of the polymerization in the binary system consisting of a vinyl monomer and a compound having no long‐chain substituents or in the homogeneous solution consisting of monomer and viscous solvent were far less than that in the presence of long‐chain compounds. It is suggested that the effect can be attributed to the effect of a special reaction matrix favorable to polymerization in the solid–liquid equilibrium.
Melting and crystallization behavior of poly(tetrafluoroethylene). New method for molecular weight measurement of poly(tetrafluoroethylene) using a differential scanning calorimeter
Authors: Suwa Takeshi , Takehisa Masaaki , Machi Sueo
Published: April 2003

Melting and crystallization behavior of virgin polytetrafluoroethylene have been studied using a differential scanning calorimeter. Following quantitative relationship was found between number average molecular weight of polytetrafluoroethylene and the heat of crystallization in the molecular weight range of 5.2 × 105 to 4.5 × 107: M̄n = 2.1 × 1010 ΔHc−5.16, where M̄n is number average molecular weight and ΔHc is the heat of crystallization in cal/g. The heat of crystallization is independent of cooling rate ranging from 4 to 32°C/min. This relationship provides a simple rapid and reliable method for measuring the molecular weight of polytetrafluoroethylene.
Viscoelastic and friction characteristics of polydiene, and butadiene–styrene copolymer tread compounds with application to tire dynamics
Authors: White James L. , Lin Yih Ming
Published: April 2003

An experimental study of the linear viscoelastic and friction properties of passenger tire tread compounds containing realistic black and oil contents and several different types of elastomers including cis‐polyisoprene, cis‐polybutadiene, emulsion polymerized polybutadiene, and three emulsion polymerized butadiene—styrene copolymers (SBR's) has been carried out. E′ (ω) and tan δ were determined as a function of frequency and temperature. At any specific frequency and temperature, tan δ was an increasing function of Tg or a decreasing function of T − Tg. When the tan δ–frequency data were plotted at the same T − Tg, all of the treads based upon emulsion‐polymerized butadiene polymers yielded nearly the same curve. Wet coefficients of friction of the tread compounds correlated with both tan δ and T − Tg supporting the idea that lubricated friction is largely due to hysteresis. The correlation among the butadiene—styrene polymers was much better than with the natural rubber, which exhibits a lower tan δ and a higher wet coefficient of friction than an SBR of the same Tg. The experimental results are used to investigate the heat buildup and skid properties of tires containing these tread compounds.
Characterization of drag reduction and degradation effects in the turbulent pipe flow of dilute polymer solutions
Authors: Ting R. Y. , Little R. C.
Published: April 2003

Turbulent drag reduction data were obtained at Re = 9000 in a 0.62‐cm‐I.D. pipe for five Polyox compounds covering a wide range of molecular weights. The concentration dependence of drag reduction was shown to obey an improved form of Virk's drag reduction equation, which was previously applied only to flows in capillary tubes. The efficiency of the drag‐reducing polymer additives on a unit concentration basis at infinite dilution was determined by using a characteristic parameter, DRm/[c], for each compound. A linear relationship was found to exist between this parameter and polymer molecular weight. The polymer degradation data were analyzed through use of a variable related to the dissipated energy in the wall region. The polymer molecular weight was found to decrease as a hyperbolic function of the dissipated energy function. By examining the change of molecular weight with respect to this function, a degradation index characteristic of the entire Polyox polymer family was established. This index may be of general application and provide a method by which the shear stability of various species of drag‐reducing polymers may be meaningfully compared.
Applications of gel permeation chromatography. III. Formulation
Authors: Schrager Morton
Published: April 2003

This paper describes a general theory for the optimization of multicomponent blending to achieve a desired chromatographic distribution. A procedure for compound blending is also discussed, where optimum replication of both the chromatographic spectra and a second independent parameter can be achieved. Lastly, this theory is applied in a hypothetical example.
Dynamic mechanical properties of some epoxy matrix composites
Authors: Jenness J. R. , Kline D. E.
Published: April 2003

Dynamic mechanical properties of some epoxy matrix composites have been studied, comparing experimental data with theoretical models. The matrix in all composite samples was Shell Epon 828, a diglycidyl ether of bisphenol A, cured with meta‐phenylenediamine. Fibrous composite samples were made with glass and graphite fibers. Particulate composite samples were made with glass microspheres, atomized aluminum, powdered silica, alumina, asbestos, mica, carbon black, and graphite. The dynamic elastic modulus and damping of these samples were measured at temperatures between 85° and 345°K by a free‐free flexural resonance technique. The dynamic modulus of parallel fiber composites follows the linear rule of mixtures for low fiber volume fractions; deviations from linearity at higher volume fractions appear to be due to defects caused by the sample fabrication technique. Dynamic moduli of the particulate composites conform, within experimental error, to the static modulus theory of Wu up to filler volume fractions of 0.35 to 0.40. Deviations from Wu's theory at higher volume fractions may be due to agglomeration of filler particles. The damping of particulate composites with quasi‐spherical filler particles appears to follow the rule of mixtures. In particulate composites with needle‐ and flake‐type fillers, and in fibrous composites, the fillers are more highly stressed; with more of the strain energy in the low‐damping fillers, overall damping is reduced. Damping greater than that attributable to the matrix and filler may be due to slippage at the interface between them. In addition to supporting Wu's theory of the elastic modulus of a particulate composite, this study demonstrates the utility of the nondestructive free‐free flexural resonance techniques for obtaining a large body of reliable data in a short time from relatively few small samples. This greatly facilitates the experimental testing of theoretical models and the evaluation of fillers, matrix materials, and fabrication techniques.
Mechanism for the action of tackifying resins in pressure‐sensitive adhesives
Authors: Sherriff M. , Knibbs R. W. , Langley P. G.
Published: April 2003

In a study of pressure‐sensitive adhesives prepared from mixtures of natural rubber and three different tackifying resins, it was shown that a tackifying resin may form either one‐ or two‐phase systems with natural rubber. Measurements of the viscoelastic properties of the adhesives show that the effect of tackifying resins is to modify the viscoelastic properties so that the adhesive performance in bonding and unbonding is improved. It is suggested that a two‐phase system is not necessary for good tack, and a theory based on a two‐phase system cannot adequately explain the rate dependence of tack tests. Tack measured by the probe test is shown to be dependent upon a balance between the viscoelastic properties and the transition temperature of the adhesives. This theory is used to explain the effect of contact time, withdrawal speed, and resin softening point on the tack of adhesives.
Nonlinear viscoelastic behavior of plasticized poly(vinyl chloride)
Authors: Dehoff P. H. , Chakrabarti M. K.
Published: April 2003

This paper shows how an empirical nonlinear creep relation suggested by Leaderman might be justified on the basis of an approximate nonlinear viscoelastic constitutive equation. In addition, experimental evidence is presented which tends to support the proposed theory.
Mechanism of the benzophenone‐sensitized photodegradation of polypropylene
Authors: Harper D. J. , McKellar J. F.
Published: April 2003

The photodegradation of polypropylene sensitized by benzophenone has been studied under accelerated light‐aging conditions using a Xenotest 150. Degradation of the polymer and consumption of the benzophenone was monitored by infrared spectroscopy. The results indicate that hydrogen stom abstraction from the polymer, by photo‐excited benzophenone, is the major primary process in the mechanism of sensitized photodegradation.
Nonlinear constrained optimization of filled polyesters
Authors: Fricke A. L. , Natarajan V. K. , Caskey J. A. , Kutat H. L.
Published: April 2003

An efficient method for optimization of a formulation problem subject to nonlinear constraints was demonstrated. Specifically, a nine‐variable polyester‐filler system was investigated experimentally. The investigation included selection of an efficient experimental design, regression analysis, and study of optimization methods. Recommended procedures are reported, along with examples and discussion of several typical applications.
Etude PAR spectroscopie de la deshydratation de dérivés de l'alcool polyvinylique: Mise en evidence d'une répartition séquentielle des substituants
Authors: Moigne J. Le , Gramain Ph.
Published: April 2003

The dehydration of sulfopropylic and alkyl derivatives of poly(vinyl alcohol), with varying degrees of substitution, was observed using ultraviolet and visible spectroscopy. The dehydration reactions were carried out in a KHSO4/heptane system kept under nitrogen at 100°C. Spectroscopic results show that definite sequences of conjugated double bonds are formed. The distribution of the number and length of these conjugated sequences was determined and compared with the theoretical values obtained assuming statistical distribution of the substituents. From this work it is concluded that: (1) the grafting of propane‐sultone onto poly(vinylalcohol) molecules does not follow a random, statistical pattern, rather the reaction is sequential, i.e., of a “zip” type. The product molecules contain blocks of sulfopropylic‐substituted vinyl alcohol groups. (2) The grafting of alkyl groups onto the poly(vinyl alcohol) molecules also occurs in a sequential manner. Results obtained show that the polymer chains contain at least two unreacted hydroxyl functions between each substituent alkyl group; this is in agreement with x‐ray studies of these derivates. Further evidence of an ordered distribution of the substituents along the polymer chain is given by the heterogeneity in the compositions of the substituted polymers. The difference in the observed structures of the two substituted polymers demonstrates the importance of the nature of the substituents in determining the reaction mechanism. It is concluded that the structural differences observed are due to differences in the solubility of the sulfopropylic and alkyl reactants in the original reaction medium, and the hydrophilic and hydrophobic character of the sulfopropylic and alkyl substituents in the polymer.
On the thermal degradation of poly(vinyl chloride). I. An apparatus for investigation of early stages of thermal degradation
Authors: Abbås Kent B. , Sörvik Erling M.
Published: April 2003

A dehydrochlorination apparatus is described for studies of the early stages of the thermal degradation of poly(vinyl chloride) (PVC), combining good reproducibility, high accuracy, and a low detection limit. The evolved hydrogen chloride is absorbed in water and the electrical conductivity is continuously recorded. Measurements of the rate of dehydrochlorination repeated over an extended period of time showed a standard deviation of 2% of the mean value. The activation energies for the dehydrochlorination in nitrogen for two commercial suspension‐polymerized samples were found to be 27.9 ± 1.5 and 26.2 ± 0.6 kcal/mole.
Preparation and copolymerization of polyvalent metal salts of ethyleneglycol–methacrylate–maleate
Authors: Matsuda Hideaki , Kanaoka Kunio
Published: April 2003

Preparation of polyvalent metal salts of ethyleneglycol–methacrylate–maleate (EMM) was investigated by the reaction of Na salt of EMM and chlorides of polyvalent metals such as Al3+, Cr3+, Fe3+, Ni2+, Co2−, and Cu2+. It was found that, among the metal salts obtained, the Cr salt could be obtained in the form of (EMM)2Cr(OH) in high purity, where EMM means EMM residue,

Then, (EMM)2Cr(OH) was copolymerized with styrene, MMA, and hydroxyethyl methacrylate. In the copolymerization, the rates of copolymerization increased markedly as the concentration of (EMM)2Cr(OH) increased. As for the physical properties of the copolymers obtained, Rockwell hardness and compressive strength can be improved by introducing (EMM)2Cr(OH) into the polymers, and HDT, tensile, and flexural strengths can also be improved by selecting the most suitable concentration of (EMM)2Cr(OH) according to the species of vinyl monomer. Further, TGA and boiling water resistance of the copolymers are also discussed.