bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactivity of monomers in copolymerization
Authors: Nozaki Kenzie 
Published: April 2003

AbstractAn investigation of the copolymerization of many monomer pairs induced by benzoyl peroxide has shown that an order of monomer reactivity with radicals exists. By utilizing the data available, it was possible to make a semiquantitative arrangement of many monomers according to their relative rates of reaction with radicals. A symmetrical selectivity factor is assumed to account for deviations from the order in copolymerization reactions. This selectivity may be attributed to (1) complex formation between monomers or to (2) dipole, steric, or other factors which are independent of concentration. Copolymerization equations have been derived for each case and application of them to styrene–methyl methacrylate mixtures has indicated that selectivity due to (2) is most important in this system. The equation for case (2) has been applied to other copolymer systems.
Water‐soluble alkoxyacetals of polyvinyl alcohol
Authors: Beal K. F. , Thor C. J. B. 
Published: April 2003

AbstractPolyvinyl alcohol may be reacted with methoxyacetaldehyde, 2‐methoxyethoxyacetaldehyde, 2‐methoxyethoxyacetaldehyde, 2‐n‐propoxyethoxyacetaldehyde, tetrahydrofurfuryloxyacetaldehyde, or 3‐methoxypropionaldehyde, or with mixtures of these aldehydes, to yield thermoplastic resins which are soluble in cold water below specific temperatures peculiar to each resin, and which are soluble in most organic solvents except aliphatic hydrocarbons.
Polymerization of olefins and diolefins in suspension and emulsion. Part II
Authors: Hohenstein W. P. , Mark H. 
Published: April 2003

AbstractThis and a previous article (p. 127) review the literature from 1910‐1945 on polymerization of olefins and diolefins in suspension and emulsion, and present a number of new measurements not published to date. The subject is considered mainly from the point of view of scientific information on the mechanism of polymerization in aqueous suspensions and emulsions, but brief mention is also made of the more important disclosures in the patent literature. The new data presented in this article refer to (1) initial rates of polymerization of styrene, methyl methacrylate, vinyl acelate and acrylonitrile in aqueous suspensions and in soap emulsions as a function of catalyst concentration, temperature, and soap concentration; (2) influence of water‐soluble activators, such as sodium bisulfite; (3) influence of initial size of monomer droplets on initial rates of monomer consumption; (4) study, with the aid of the electron microscope, of size of monomer droplets and polymer particles throughout polymerization; and (5) a few experiments on side reactions in the domain of higher conversions. No attempt is made in this paper to review and appraise the very large number of recent patents (from about 1930 on), which protect special procedures on the use of various promoting, regulating, or modifying ingredients. A complete digest of this practice does not exist at present, but reference may be made to the excellent chapter on emulsion polymerization in the book of Talalay and Magat, to the very valuable compilation of patents by Hoseh, and to the enumeration of a selected number of patents in the book of Scheiber.1
Chain structure of vinyl and diene polymers in relation to polymerization mechanism
Authors: Flory Paul J. 
Published: April 2003

AbstractThe usual occurrence of structural units of vinyl polymers in head‐to‐tail sequence is attributed to the stabilization of the free radical of the growing polymer chain by the monomer substituent(s). Addition at the unsubstituted carbon of the vinyl group reproduces a free radical of lower energy than does addition at the substituted carbon. In at least one instance (vinyl acetate polymerization) a very small percentage of head‐to‐head addition takes place in spite of this energy difference. These ideas can be extended to polymers of dienes. Here the problem is complicated by the simultaneous occurrence of 1,2 (or 3,4) as well as 1,4 addition. In the case of an unsymmetrical diene monomer such as isoprene it is possible, from detailed examination of the structure of the polymer, to distinguish between preferred addition at carbon atoms 1 and 4 of the monomer.
Mercaptans as promoters and modifiers in emulsion copolymerization of butadiene and styrene using potassium persulfate as catalyst. I. Mercaptans as promoters
Authors: Kolthoff I. M. , Harris W. E. 
Published: April 2003

AbstractThe rate of emulsion copolymerization of butadiene and styrene, with soap as emulsifier and potassium persulfate as catalyst, is extremely small at 50°C. The presence of very small amounts of high‐molecular mercaptans promotes the copolymerization reaction. The promoting effect is at a maximum for primary, secondary, and tertiary dodecyl mercaptans and decreases for mercaptans of either higher or lower molecular weight. The promoting effect is independent within wide limits of the amount of mercaptan added after the minimum quantity has been exceeded. Mercaptans which are poor promoters may be so because they fail to bring about chain initiation or because they aid in chain termination. The low‐molecular mercaptans which are poor promoters prevent the high‐molecular mercaptans from exerting their good promoting effect when a mixture of both types of mercaptans is used. The mechanism of the promoting effect of mercaptans upon the emulsion copolymerization of butadiene (75 parts) and styrene (25 parts) or upon the polymerization of butadiene alone is not yet clear.
Copolymerization. I. Kinetics and some experimental considerations of a general theory
Authors: Melville H. W. , Noble B. , Watson W. F. 
Published: April 2003

AbstractA review of theoretical progress in copolymerization has shown that the results of previous authors are consistent and equivalent. A general scheme of copolymerization has been stated and its kinetic consequences worked out. The rate expressions have been derived for percentage polymerization against time, and initial rate against initial monomer concentration. Some experimental considerations have been given. The advantages of photochemical technique have been stressed, physical means of following the reaction outlined, and new methods of determining σ and μ described. Means of verifying the kinetics have been suggested, in particular the obtaining of the individual velocity constants. It is important to note in this connection, that further experiments to determine the lifetime of the growing polymer chain are not required.
Effect of centrifugal field on resistance to motion of threadlike molecules in solution
Authors: Singer Seymour J. 
Published: April 2003

AbstractAn attempt has been made in this communication to formulate explicitly the dependence of the frictional coefficients of threadlike molecules in solution upon the centrifugal field applied to them in the usual velocity ultracentrifuges. This quantitative treatment, using the Kuhn and Kuhn odel for randomly coiled free‐draining thread molecules, verifies the assumption generally made that the effect considered is negligible. Since the molecular weight of the particles and the magnitude of the centrifugal field applied to them vary inversely with each other, the constant, \documentclass{article}\pagestyle{empty}\begin{document}$\overline {\beta h_0^2 }$\end{document} rarely attains values which are significant, and the effect produced by orientation of the threads is balanced by the effect due to stretching them. Moreover, by a suitable change of parameters, this treatment could be extended to account for the action of other tensile forces acting on thread molecules in solution
X‐ray and moisture equilibrium investigation of sodium pectate
Authors: Palmer K. J. , Shaw T. M. , Ballantyne M. 
Published: April 2003

AbstractThe variation of the x‐ray reflection to the interchain separation in sodium pectate has been determined as a function of moisture content. The crystalline regions in sodium pectate have been found to sorb about 24% water (dry basis) at a relative humidity of 95% at 25°C. The sample as a whole under these conditions has a water content of 64%. At high water contents, therefore, a large difference in water content must exist between the crystalline and amorphous regions of sodium pectate. A marked change in degree of crystallinity occurs, as determined by the number and sharpness of the x‐ray reflections, at an average water content of about 6% on desorption and on sorption at an average water content of about 14%.
Heats of combustion and solution of liquid styrene and solid polystyrene and heat of polymerization of styrene
Authors: Roberts Donald E. , Walton William W. , Jessup Ralph S. 
Published: April 2003

AbstractBomb calorimetric measurements have yielded for the heats of combustion (—ΔHoc) at 25°C. of liquid styrene and solid polystyrene to form gaseous carbon dioxide and liquid water the values 4394.88 ± 0.67 int. kjoule per mole (1050.58 ± 0.14 kcal. per mole), and 4325.09 ± 0.42 int. kjoule per C8H8 unit (1033.89 ± 0.10 kcal. per C8H8 unit), respectively, and for the heat of polymerization of liquid styrene to solid polystyrene at 25°C. the value 69.79 ± 0.66 int. kjoule per mole (16.68 ± 0.16 kcal. per mole). The results obtained on two samples of polystyrene of different molecular weight were in agreement within the precision of the measurements. Measurements of the heat of solution of solid polystyrene in liquid monomeric styrene gave the value 3.59 ± 0.21 int. kjoule (0.86 ± 0.05 kcal.) evolved per C8H8 unit of polystyrene at 25°C. Addition of this to the value for the heat of polymerization of liquid styrene to solid polystyrene gives the value 73.38 ± 0.69 int. kjoule (17.54 ± 0.16 kcal.) per mole of styrene for the heat of polymerization of liquid styrene at 25°C., when the final product is a solution of polystyrene in styrene containing 6.9% by weight of polystyrene.
Light‐induced polymerization of some monomers containing allyl and methacrylate groups
Authors: Cohen S. G. , Ostberg B. E. , Sparrow D. B. , Blout E. R. 
Published: April 2003

AbstractIn the polymerization of ally1 methacrylate in the presence of benzoyl peroxide at 75°C., gelation occurs after about 6% reaction. By carrying out the polymerization a t 1°C. to 25°C. in the presence of biacetyl or benzoyl peroxide and photoflood or ultraviolet radiation, we have been able to postpone gelation until 19 to 39% reaction. In the presence of biacetyl the extent of reaction a t the gel point is increased as the temperature is lowered and as the light intensity is raised.Biacetyl is activated by radiation in the 400–460 mμ region; benzoyl peroxide is activated by radiation in the 350–380 mμ region.Hydrolysis and bromination of the soluble polymer did not indicate any marked difference in the composition of the samples prepared at 75°C. and 15°C. The soluble polymer which is prepared at 75°C. appears to have an intrinsic viscosity which may be three to twenty times as great as that of the polymer which is prepared at 1–25°C.The polymerization of methyl methacrylate and allyl acetate under the two sets of conditions indicated that the reaction of the methacrylate was affected more than that of the allyl compound by the change in conditions. The copolymerization of methyl methacrylate and allyl chloroacetate indicated that somewhat more allyl monomer was incorporated into the copolymer at the lower temperature than a t the higher temperature.The increased extent of reaction at the gel point at the lower temperatures appears to be due almost entirely to diminished molecular weights. The decrease in molecular weight a t low temperatures is probably due to the decreased rate of chain growth, the rate of initiation remaining high because of irradiation, and the rate of termination being little dected because of its low activation energy. The effects of temperature on the composition of the copolymer, and of molecular weight on the point of gelation, are discussed briefly.
Magnetic rotatory power of liquid polymers
Authors: Lagemann Robert 
Published: April 2003

AbstractThe Verdet constants of nine polyethylene glycols, three polypropylene glycols, and nine silicone polymers have been measured at 25°C. It was found that the Verdet constant increases with increase in molecular weight in each of the series, and approaches a constant value. A similar increase in the molecular magnetic rotation was noted. The results are in contrast with those on polystyrene, and the effect of end groups on the measurements is discussed in explanation.
Stress‐strain characteristics of guaran triacetate
Authors: Smart Charles L. , Whistler Roy L. 
Published: April 2003

AbstractGuaran triacetate, a linear molecule having one‐unit branches, can be cast into clear, colorless films having a tensile strength of 7.5kg./mm.2 and an elongation at break of 4%. Thus, it appears that one‐unit branches of the size of the glycosidic unit do not adversely affect the film‐formingproperties of polysaccharide acetates. Plasticized films show more elasticity and greater elongation at break.
Simple presentation of network theory of rubber, with a discussion of other theories
Authors: James Hubert M. , Guth Eugene 
Published: April 2003

AbstractThe approximations implicit in the use of the Gaussian network model for soft rubber are discussed. It is shown that the form of the stress–strain curve can be derived for this model simply, and without special assumptions about the form or behavior of the network. The common assumption that the network junctions are fixed, or can be treated as fixed, is discussed. It is shown that this picture of the situation is unrealistic: the junctions have a Brownian motion comparable to that of any portion of the intervening molecular segments. The introduction of this assumption is not generally admissible, but it will not affect the outcome of certain types of calculation; in particular, one can foresee that it need not affect the calculated form of the stress‐strain curve. A particularly simple and straightforward calculation of the network entropy on this basis is given. Wall's the ory of rubber is analysed. It is shown that Wall's postulates are not consistent with the network structure of rubber, and in general lead to different results.
Water content of hydrophilic phenol‐formaldehyde resins: Vapor pressure‐temperature relationships
Authors: Bentz Ralph W. , Neville Harvey A. 
Published: April 2003

AbstractThe significance of the water content to the physical properties of phenol‐formaldehyde resins at various stages of preparation is briefly discussed. Available methods for the determination of water in such resins were found to be either unreliable or too elaborate for process control. It was undertaken to develop a simple, rapid, relative method for the continuous measurement of water content which can be used to follow the follow the process of dehydration and to indicate the end‐point which will result in the best dispersion of water in the cured resin. In order to standardize or calibrate such a relative method, it was necessary also to develop an absolute method for the analysis of water in the resol.The composition of a homogeneous mixture of liquids is reflected by its vapor pressure‐temperature relationships. During dehydration at 80°C., the vapor pressure of the resol decreases about 350 mm. of mercury. A very sharp increase in the slope of the vapor pressure curve occurs at approximately the proper degree of dehydration. At this stage a slight decrease in water content causes a very large decrease in vapor pressure. The sharp inflection in the curve is attributed to the existence of both “free” and “bound” water in the resin.During the process of vacuum dehydration of the resin, while the “free” water decreases to approximately one‐eighth of its original content, the “bound” water remains substantially constant. The binding of water is attributed to the methylol groups of the resol molecules and its release during the cure or hardening of the resin is considered to result from the conversion of these groups to methylene linkages.
Koresin and related resins
Authors: Marvel C. S. , Gander Robert J. , Chambers R. R. 
Published: April 2003

AbstractThe infrared and ultraviolet absorption spectra of Koresin are very similar to those of an acid‐catalyzed p‐tert‐butylphenol‐acetal‐ dehyde polymer. This is believed to be evidence that Koresin has Structure I. A variety of phenol‐aldehyde resins have been prepared for comparison with Koresin. The ratings of some of these materials as tackifiers have been reported. These furnish further evidence that the molecular weight of a phenol‐aldehyde resin is important in its tackifying action. An alkaline‐catalyzed condensation product of acetylene and p‐tert‐butylphenol shows no tackifying action and has no free hydroxyl in the polymer as judged by its infrared pattern.
Ultraviolet absorption spectra of some copolymers containing acenaphthylene, and of related compounds
Authors: Herington E. F. G. , Jones J. Idris 
Published: April 2003

AbstractThe strong ultraviolet absorption in the wave‐length region 280‐330 mμ shown by copolymers of acenaphthylene with styrene or methyl methacrylate is due to acenaphthylene residues. The spectra of samples of copolymer containing a small percentage of acenaphthylene are different from the spectrum of polyacenaphthylene. As a result of the comparison of the spectra of these copolymers with the spectra of acenaphthene and with the two forms of 1,1′‐biacenaphthyl it is concluded that spectra of the copolymers can be explained as arising from the presence of pairs of acenaphthylene groups. Finally it is shown that the spectra can be used to estimate the acenaphthylene contents of the copolymers.
Rheology of thermoplastics. II. Recoverable and nonrecoverable deformations of polystyrene between 90 and 240°C. as a function of molecular weight
Authors: Buchdahl R. , Nielsen L. E. , Merz E. H. 
Published: April 2003

AbstractThe rheological properties of polystyrene have been studied between 90 and 240°C. as a function of molecular weight. Three different methods have been used to obtain the data: rotational viscometer, extrusion‐type capillary viscometer, and tensile creep measurements. It has been shown that the nonrecoverable (viscous) deformation is a function of molecular weight whereas the recoverable deformations are, within the investigated molecular weight range, practically independent of chain length. An explanation of this observation is suggested, based on the assumption of a labile network structure, which explains also the effect of “previous history” on the recoverable deformations. The temperature dependence of the recoverable and nonrecoverable deformations is shown to be very similar. Experimental evidence is presented to show that the dependence of the viscosity on shear stress (or rate of shear) is not a simple power relationship but is of the sigmoidal type. It is shown that the creep or compliance function a few degrees below the second‐order transition point does not depend on the weight‐ or number average molecular weight.
Structure and thermodynamics of elastomeric microgel
Authors: Medalia A. I. 
Published: April 2003

AbstractMicrogel consists of branched molecules of colloidal dimensions, formed by gelation occurring within the confines of a latex particle. It is shown that microgel should be (thermodynamically) soluble but, because of the large sue of each molecule, it settles out of solution. The proportion of subchains which are connected to centers of cross‐linkage at one end rather than both ends is calculated for gelled molecules of various values of the branching coefficient.
Determination of microgel in GR‐S rubber
Authors: Medalia A. I. , Kolthoff I. M. 
Published: April 2003

AbstractMicrogel consists of branched molecules of colloidal dimensions, formed by gelation occurring within the confines of a latex particle. Thermodynamically, microgel is expected to be soluble in a “good” solvent, such as benzene. Experimentally, it is found that carefully dried microgel‐containing polymers are completely soluble in benzene. Detection of microgel by solubility measurements requires the conversion of microgel to macrogel (gel of macroscopic dimensions) prior to the solubility measurement. This can be accomplished by heating under a variety of conditions. Milling of the polymer before heating aids in this conversion.A Standard Procedure is recommended for the determination of microgel in standard GR‐S rubber: the polymer (preferably coagulated in ethanol) is milled for about 10 passes, with the addition of 2% of phenyl‐beta‐naphthylamine; the milled polymer is heated for 12 hours in a vacuum oven at 80°, then placed inside a box of wire screen and immersed in benzene for 40 hours to extract the sol portion.Solutions of microgel in benzene can be fractionally precipitated by addition of ethanol or nitroethane. The fractionation is, primarily according to molecular weight rather than degree of cross‐linkage. Viscosity and light‐scattering measurements of the fractions show that the polymers are of high molecular weight and are cross‐linked.
Polyelectrolytes. VIII. Quaternized polyesters of succinic anhydride and methyldiethanolamine
Authors: Fuoss Raymond M. , Edelson David 
Published: April 2003

AbstractLinear polyelectrolytes have been prepared by quaternizing with methyl bromide the polyester obtained by condensation between succinic anhydride and methyldiethanolamine. Molecular weights, determined by end group titration, were in the range 2000‐43,000. The polysalts hydrolyze in water but are stable in absolute methanol. Viscosities in methanol of the polysalt of highest molecular weight conform to the empirical equation:

Conductance curves are sharply concave upward on a Λ − c1/2 scale, indicating a high degree of association of counter ions with the polycation at finite concentrations. Estimates of limiting mobility suggest a curved rodlike structure for the polycation at infinite dilution.
Adhesion of polyethylene and polystyrene to steel
Authors: Kraus Gerard , Manson James E. 
Published: April 2003

AbstractA conservative estimate of the molecular forces involved in the adhesion of polymers to conducting surfaces leads to bond tensile strengths considerably above those realizable in practice. This is explained by the occurrence of flaws, thermal stresses, and deformation under load. In order to minimize these factors, very thin films of polystyrene and polyethylene were molded between steel cylinders and experimental conditions were carefully controlled with the result that joint strengths in excess of bulk tensile strengths were obtained. Curves of joint failure stress versus film thickness at various temperatures are given, and extrapolated to zero thickness. The extrapolated adhesion values represent a lower limit of the specific adhesion. At 25°C. they are 183 kg./cm.2 for polyethylene, and 412 kg./cm.2 for polystyrene.