ISSN:0022-3832    

DOI:10.1002/pol.1947.120020201

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractFor satisfactory performance in vinyl chloride‐acetate resins, plasticizer must be compatible with the resin in a wide range of concentration. Low volatility low rates of extraction by oil and water, and good chemical stability are necessary in most applications. In special applications good electrical properties, low flammability, preservation of compound flexibility at low temperatures, and freedom from odor and taste are also required. Physical test methods, suitable for the evaluation of plasticizers, are briefly describe

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020202

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractThe conventional thermodynamic theory of solvent action is briefly reviewed. A mechanistic theory is advanced to supplement the thermodynamic theory. The mechanistic theory views a resin solution as an example of dynamic equilibrium between the tendency of the solvent molecules to solvate the resin and the tendency of the resin macromolecules to unite with each other in three‐dimensional aggregation. A plasticizer, being a nonvolatile solvent, remains in the resin film on evaporation of the solvent and thus opposes, to an extent depending on its concentration and solvent strength, the aggregation of the resin macromolecules. Although the permanence of plasticizers in resinous compositions does not correlate well with the author's measure of the relative solvent strengths of the plasticizers, very satisfactory correlation is obtained between the low‐temperature behavior of plasticized films and the temperature dependence of the solvent strength of the plasticizers. Data are presented in support of the contention that a necessary condition for good low‐temperature performance in plasticized resinous compositions requires that the plasticizer must show a considerable improvement in solvent strength on co

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020203

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractThe elastic and plastic properties of high polymeric materials are functions of the forces holding the molecules together and the ability of small segments of the chains to move about, relative to other segments. Internal plasticization is accomplished by introducing structural features which reduce intermolecular and intramolecular forces and which, in general, decrease the order of the polymer. Physical techniques used to determine the effect of such structural features have been discussed. The results of numerous investigations into the relations between structure and properties have been considered in an attempt to present a simple and consistent physical picture of these relations.

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020204

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractThis is a review article concerned with the effect of plasticizers on the second‐order transition point and related phenomena in high polymers. The second‐order transition temperature behavior of plasticized polymers can be described by a linear relationship between the square root of the weight fraction of polymer and the reciprocal transition temperature. For certain temperature regions and plasticizer contents, this is mathematically equivalent to the linear decrease of transition temperature with plasticizer content which is also observed experimentally. This latter result is in accord with Zhurkov's theory of the softening action of solvents, which predicts a linear decrease in softening temperature with solvent content, and no dependence on the nature of the solvent. Neither the second‐order transition approach nor Zhurkov's theory permits conclusions about the nature of the plasticizer. However, it is shown empirically that brittle temperature can be represented as a function of the solvent‐polymer interaction constant μ by a curve having a maximum at μ ≈ 0.4. Since μ is also the parameter which measures compatibility, it is seen that the efficiency and the compatibility of a plasticizer are intimately related. Moreover, correlation can be made with older observations showing the relation between efficiency and the temperature coefficient of viscosity of the

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020205

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractThe viscoelastic properties of plasticized Vinylite VYNW were studied over a wide range of time scale by means of the tensile creep test. A number of different plasticizers were compared as to their plasticizing effectiveness. It was found that different plasticizers imparted distinctly different shapes to the creep curve of the plasticized ferent plasticized resin. The flat creep curve, characteristic of trioctyl phosphate, is considered to be superior to the steep creep curve of tricresyl phosphate. Mixtures of plasticizers were also studied. A number of conjectures are advanced concerning the molecular mechanism of plasticizer action. One important characteristic of a plasticized formulation of the polyvinyl chloride types of resin is the existence of a three‐dimensional gel structure of great permanence which prevents the occurrence of irrecoverable viscous flo

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020206

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractThe preparation of perbenzoic acid has been investigated in a n attempt to obtain standard solutions of perbenzoic acid suitable for the amlyszk of unsaturated compounds. Some modifiations of the procedure given by Braun for the preparation of a solution of perbenzoic acid in a n organic solvent are recommended. A study has been made of the stability of solutions of perbenzoic acid in chloroform and in benzene. Benzene or benzene‐chloroform mixtures are recommended as solvents for perbenzoic acid. Chloroform solutions of perbenzoic acid which do not contain inhibitors for decomposition have been found to be definitely undesirable in analytical work because perbenzoic acid catalyzes the decomposition of chloroform by oxygen. construction Finance Corporation, in connection with the Government Synthetic Rubber Progra

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020207

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractA procedure is given for the determination of the external double bonds in synthetic rubbers. The method is based on the difference in the rates of reaction of perbenzoic acid with internal and with external double bonds. The principles of the interpretation of the analytical data are discussed. Calibration curves for use in the analysis of butadiene and isoprene polymers are given. The procedure is also applicable to the analysis of a mixture of two compounds, one of which contains an external double bond and the other an internal double bond. Data are given for the analysis of mixtures of oleic acid and undecylenic acid.

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020208

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

AbstractEmulsion polybutadiene and emulsion copolymers of butadiene and styrene (e.g., GR‐S) contain about 20% external double bonds. A systematic study has been made of the effects of temperature, type of “catalyst,” percentage conversion, microgel formation, and varying styrene content of emulsion copolymers of butadiene and styrene. None of these variables affects the amount of external double bonds. Copolymers of butadiene with styrene and a small amount of acrylonitrile, and of butadiene with various monochlorostyrenes and dichlorostyrene, all prepared by emulsion polymerization, were found to contain the same amount of external double bonds. Emulsion polyisoprene and the emulsion copolymers of isoprene and styrene (75:25) were found to contain only 13 and 5%, respectively, external double bonds. Polybutadiene, butadiene—styrene copolymer, and polyisoprene, all prepared by sodium—catalyzed, bulk polymerization at 50°C., contain 50–60% external double bonds. The amount of external double bonds in sodium polybutadiene is strongly dependent on temperature of polymerization. More external double bonds are formed at low temperatures than at high temperatures. The amount of external double bonds in sodium butadiene—styrene copolymer and in sodium polyisoprene is nearly independent of temperature in the range 30–50°C. A sample of sodium polyisoprene was found to contain 36% internal double bonds and 64°C external double bonds. From an analysis of the reaction—rate curve it was concluded that approximately 40% (absolute percentage) of the external double bonds were formed by 3,4 addition and 24% by 1,2 addition. The rates of reaction of the cis—and trans—forms of natural rubber are very nearly the same, the cis—form reac

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020209

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY

摘要:

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 require

ISSN:0022-3832    

DOI:10.1002/pol.1947.120020210

出版商:Interscience Publishers, Inc.    

年代:1947

数据来源: WILEY