摘要:

AbstractThe present paper describes the preparation and evaluation of the effectiveness as modifiers of a number of compounds of bis‐type structure—principally aryl disulfides—in bulk styrene and emulsion butadiene polymerizations. This work endeavors to explore some of the objectives described in the first paper of this series, and deals primarily with attempts to gain quantitative information on the effect of the nature and location of substituting groups with respect to the dissociating bond. The compounds examined include both those containing reactive groups attached and those lacking such groups. A number of the preparations are now compounds. Evaluations in 50°C. bulk styrene were carried out with the objective of eliminating the complications of the diffusion factor always present in emulsion systems. Generally speaking, the correlation between effectiveness in bulk styrene and 50°C. emulsion butadiene was quite good, though there were exceptions. It was found that the modifier activity of many compounds in emulsion butadiene could be enhanced by predispersing them in the aqueous phase—presumably a result of minimizing the importance of diffusion rate. Some of the modifiers were also tested in a low temperature butadiene emulsion system. Aryl disulfides continue to offer the most promise from the standpoint of combining the features of attaining high transfer constants and ease of incorporating desired reactive groups. Some compounds had adequate activity in emulsion butadiene polymerizations for use as practical modifiers. However, it has not yet been established that these compounds cleave to give one‐half the molecule on each end of the butadiene polymer chain, as has been done for styre

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178501

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe effect of strong uniform electric field on the statistical configuration and the light scattering of linear chain polymers in solutions is studied. The statistical configuration of linear chain molecules is affected by the mutual interactions between the dipoles attached to the segments of the molecules and the external electric field. The radial distribution function of molecular segments from arbitrary chosen segment and that around the center of gravity of the molecule are calculated. The distribution functions are not spherically symmetric, and show that the molecules are slightly stretched toward the applied electric field. Using the radial distribution function calculated, we calculated the angular distribution of the intensity of scattered light by the deformed chain molecules. The intensity of scattered light is dependent on the magnitude of the applied electric field and the relative orientation of the incident ray, scattered ray, and electric field. Several special cases are illustrated. The effect of electric field is most conspicuous when the incident ray is parallel to the electric field and the scattered angle is 180°. We observed the effect of electric field on the light scattering of polyvinyl chloride molecules in diethylene oxide at the field intensity of 3000 v./cm. and the concentration 1%

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178502

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe orientation of the crystallites in spherulites was investigated by using special microbeam x‐ray techniques. The materials studied were: polyhexamethylene adipamide and sebacamide, polyethylene, and polyethylene terephthalate. In all these substances thecaxes (molecular chains) were perpendicular to the radii of the spherulites, with some deviation from strict perpendicularity in the case of polyethylene terephthalate. The particular orientation of the crystallites around theircaxes was in full agreement with the observed sign of birefringence, in the positive and negative polyamide spherulites, in polyethylene (where the indirect deduction made in earlier works has also been confirmed), and in the negative spherulites of polyethylene terephthalate. In the positive polyethylene terephthalate spherulites, while a fit between x‐ray results and birefringence might still be possible, it is somewhat doubtful whether the sign of birefringence could be accounted for by the crystallite orientation alone. The possible arrangements of the crystallites is discussed and it is suggested that the picture of closely coiled helices with the molecules lying along the winding direction might offer the most satisfactory explanat

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178503

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe activity of silver ion was measured potentiometrically with various sample solutions of silver or silver‐sodium salt, prepared from three different kinds of carboxymethylcellulose, for the purpose of elucidating these several points: dependence of the activity coefficient of counter ion upon the concentration of polyelectrolyte in salt‐free solutions; influence of the silver content of the sample upon activity coefficient; salt effect on activity coefficient; and dependence of activity coefficient upon the degree of neutralization. These experimental results indicate that the characteristics of polyelectrolyte solutions are in many respects quite different from those of simple electrolyte solutions. The applicability of the theory proposed by Ōsawa, Imai, and Kagawa is discussed in some detail, although the discussion is restricted to the salt‐free syste

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178504

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractAn attempt is made at giving a quantitative explanation for the variation of the apparent cross‐termination coefficient in copolymerization as a function of the composition of the reaction mixture. The formula developed is applied to the system butyl acrylate‐styr

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178505

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractExposure to high energy radiation offers a means of producing controlled branching in long chain polymers. Branched silicone polymer molecules were obtained by exposing linear molecules to high energy radiation. The increase in weight‐average molecular weight calculated theoretically from the radiation dose was compared with the value deduced from measurements of intrinsic and bulk viscosity, ignoring the effect of branching. The ratio of these measurements show the apparent reduction in molecular weight (as measured by viscosity methods) when branched molecules are present. In particular it is found that the reciprocal bulk viscosity decreases uniformly with degree of branching (or crosslinking) until the gel point, when the weight‐average and bulk viscosity become infin

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178506

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractA polymethyl methacrylate polymer, prepared by the emulsion technique, was fractionated three times to obtain essentially homogeneous fractions. The intrinsic viscosities and weight average molecular weights were determined in an ideal solvent at 23°C. and in nonideal solvents at 25°C. The constantsKandain the conventional modified equation [η] =KMawere determined. The intrinsic viscosity in an ideal solvent was found to fit closely over the molecular range studied with the relation [η]θ=KM1/2. Light scattering measurements giving root‐mean‐square distance between ends of a polymer chain were carried out. It was shown that these results support both Kuhn's relation (r̄2)1/2≈︁M0.50and Flory's relation (r̄2)3/2=M[η]/2.1 × 1021in an ideal solvent. In a nonideal solvent only Flory's relation was found to be in agreement with the experimental results. The values of volume expansion factor α3ratiosA2M w2/(r̄2)3/2andA2Mw/[η] in a nonideal solvent and the value of the ratio [η]/M1/2in an ideal solvent showed that the polymer molecules were expanded beyond their random flight dimensions

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178507

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178508

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178509

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe structure of certain novolacs, prepared by polycondensation of formaldehyde with phenol,p‐cresol, andm‐cresol respectively, was investigated. The novolacs were transformed into saturated hydrocarbons, thus expelling the oxygen, by a relatively mild high pressure hydrogenation (300°C., 250 atm.) using 100% by weight of a nickelcopper on kieselguhr catalyst. It can be expected that this treatment does not alter the structural frame of the molecules. From ultimate analysis and physical constants of the hydrocarbons, conclusions were made as to the structure of the novolacs. They are linear thermoplasts; no “extra” rings are

ISSN:0022-3832    

DOI:10.1002/pol.1955.120178510

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY