摘要:

AbstractThe diffusion of polymethacrylic acid in salt‐free aqueous solution has been investigated. At high degrees of ionization the diffusion coefficient is independent of concentration and of the degree of polymerization. However, it depends markedly on the degree of ionization. The hydrodynamic resistance of the polymer ion is calculated from the diffusion coefficients by allowing for the osmotic behavior of the polyelectrolyte in solution. The results, which are discussed, indicate a rodlike shape for the molecule at high degrees of ionization. At zero degree of ionization (polymethacrylic acid in an acid medium) the diffusion coefficient is nearly independent of concentration. It is inversely proportional to the square root of the degree of polymerization, showing that the un‐ionized molecule is not rinsed by the solvent. A quantitative comparison of the diffusion coefficient, with the intrinsic viscosity of the same solution, shows that there is fair agreement with the theory of Kirkwood and Rise

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158001

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractA detailed study has been made of the intrinsic viscosity‐molecular weight relationship for a polybutadiene prepared at 50°C. and one prepared at 5°C. Original fractions were at least twice refractionated from very dilute solutions in an attempt to obtain fairly sharp distributions. Fox‐FloryKconstants are observed to decrease with increasing molecular weight in each case, and the intrinsic viscosity‐molecular weight plots show a curvature. This is interpreted to be a result of branching. A method of plotting the data is proposed which simultaneously yields theKfor unbranched material and an estimate of the degree of branching. It is estimated that, in polybutadiene prepared at 50°C., one out of 6500 monomer units is involved in a branch, and that in 5°C. polybutadiene, one out

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158002

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractThe ethylenediamine‐cellulose complex, previously described by Trogus and Hess, has been reinvestigated with regard to its stability toward a series of solvents and to the differences in the fine structure of the cellulose remaining after its decomposition. It is shown that nonpolar solvents which do not contain oxygen have little effect on the complex; they do not reduce the diamine content or alter its crystal structure. On the other hand, it has been found that polar, oxygen‐containing solvents almost completely remove the diamine and, in general, cause a reconversion of the crystal structure to the cellulose I crystalline modifications. The nature of the fine structure of the cellulose remaining after decomposition of the complex is discussed in relation to the directive or orienting influence of the solvent used for the decomposition. It is shown empirically that the directive influence of a solvent is related to its polarity and to the temperature at which the decomposition is effec

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158003

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractMolecular weight, sizes, and second virial corfficients of a linear polydimethylsiloxane polymer (MW= 4.57 × 105) in mixtures of toluene‐diethylphthalate have been determined by light scattering. Intrinsic viscosities have also been measured in the same mixed solvents. As expected, as the diethylphthalate concentration was increased the molecules contracted and the second virial coefficients became more negative. The data were used to attempt to decide between two current theories relating these quantities. No choice could be made. It was found that the calculated values of Flory's universal constant, φ, were much smaller than those usually obtained. It is proposed that this is due to an abnormally broad molecular weight distribution in the polysilox

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158004

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractCellulose nitrates of average DP 130 to 2400 and of various DP distributions were degraded in ethyl acetate solutions by ultrasonic energy at 400 kilocycles. A method of comparing degradation rates of samples degraded at different concentrations is described. The degrees of degradation found were in accord with the theory of Schmid and co‐workers, and the minimum degradable chain length was calculated to be 980 DP in this system. Where compared with degradation by alkaline aging, ultrasonic degradation gave a much more uniform chain length distribution. After ultrasonic treatment, 60% of the sample was of DP 700 to 1200, while the alkaline aged sample had less than 40% in this same range and a much larger amount of short chain length material. The results do not give any indication of the presence of any physically or mechanically weak chain links at any interval near 500 D

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158005

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractOn the basis of simple assumptions, equations are derived for predicting the specific volume‐temperature‐molecular weight (v‐T‐M) relationships for a homologous series of polymers from thev‐Tcurves for the monomer and the polymer of infinite molecular weight. Analogousv‐T‐ρ relationships (where ρ is the degree of crosslinking) are similarly obtained. The result, thatvdecreases linearly with decreasing 1/Mand with increasing ρ, conforms with the picture that either the removal of two chain ends (asMincreases) or the introduction of a crosslinkage involves, between two polymer segments, the exchange of a van der Waals bond for a shorter covalent bond. The validity of these equations is illustrated by comparison with the observed data for polymers covering a wide range inM,T, and chemical type. For several polymer series the extrapolated value ofvat 0°K (v0) is the same for all members of the series, indicating that at this temperature the average length of the van der Waals and covalent bonds between polymer segments are the same. Assuming that the form of the linear relationship observed for polystyrene between the specific volume (vg) at the glass temperature and the value (Tg) of the latter is valid for other polymer series, equations are derived which predictTgas a function ofMfrom the limiting value of the glass temperature for a chain of infinite length, and from thev‐Tcurves in the liquid state for the monomer and for the polymer ofM= ∞. AnalogousTg‐ρ relationships are similarly obtained. According to these equations, a linear relationship between 1/Tgand 1/Mshould be obtained, which reduces at highMto a linear dependence ofTgon 1/M. Similarly, a linear dependence ofTgon ρ is predicted at low ρ. These predictions are in satisfactory agreement with data on polystyrene fractions and on crosslinked copolymers of styrene with divinylbenzene.The conclusion thatTgfor polystyrenes represent a state of iso‐free volume irrespective ofMis shown to be an approximation that is valid, within experimental erro

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158006

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractGlass temperatures are given for copolymers containing methyl methacrylate and from 0 to 100% of each of the dimethacrylates of ethylene glycol (EGDMA), decamethylene glycol (DGDMA), and 2‐ethyl‐2‐butylpropanediol‐1,3 (2‐E‐2‐B‐PDMA), and for copolymers containing from 0 to 17 mole per cent of the dimethacrylate of 2,2‐dimethylpropanediol (2‐2‐D‐PDMA). The relation betweenTgand the mole fraction of dimethacrylate in the copolymers is complex, maxima being observed for the DGDMA and 2‐E‐2‐B‐PDMA copolymers. This unexpected behavior is interpreted on the basis that the introduction of crosslinkages by copolymerization of a vinyl with a divinyl monomer affectsTgby concomitant changes in the average copolymer composition (“copolymer effect”) and the degree of crosslinking (“crosslinking effect”). The copolymer effect is obtained separately for the MMA‐EGDMA copolymers from the observedTg‐composition relation for copolymers of MMA with ethylene glycol monomethacrylate, monoisobutyrate. The crosslinking effectper seis then calculated on the basis of the assumption that the copolymer and crosslinking effects are independent and additive. For the EGDMA copolymers, it is found that the effect of crosslinking alone causesTgto increase linearly with an increase in the number (ρ) of crosslinks per gram of polymer, and that the proportionality constant is of the same order of magnitude as that observed in the preceding paper for the styrene‐divinylbenzene copolymers. This observedTg‐ρ relation is in semiquantitative agreement with the equations of the preceding paper, and lends support to the concept of additivity and independence of the copolymer and crosslinking effects upon which the observations are based. The results on the MMA‐EGDMA copolymers, together with the less extensive data on the other copolymers, indicate that the magnitude of the increase inTgfor each crosslink introduced is essentia

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158007

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractMeasurements of the thermal diffusion constant of polystyrene in toluene and butyl acetate solutions have been made. Direct observation of a moving boundary was used. There is a small change of thermal diffusion constant with molecular weight, but it is doubtful that it could be used for analytical purposes. The results for polystyrene in toluene have been compared with those obtained by Debye and Bueche with a convection‐type colum

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158008

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractStudies have been made by a sorption‐desorption procedure on the diffusion of water vapor at relative humidities of from 30 to 85% into the polymers, polyvinyl acetate cellulose acetate (37.9% acetyl), cellulose nitrate (12.0% N), 6–10 nylon, and polyvinyl alcohol. Diffusion of water in polyvinyl acetate obeys Fick's law at temperatures of from 30 to 50°C. and also at 22°C., which is below the second‐order transition. The energy of activation for diffusion of water into polyvinyl acetate is 15 kcal. per mole and at 40°C. the diffusion coefficient is 7 × 10−6cm.2/min. In contrast to the results with organic vapors, the diffusion coefficient for water is found to be independent of concentration of water in the polyvinyl acetate. Similar behavior is found for diffusion of water at 40° into cellulose acetate, cellulose nitrate, and 6–10 nylon. The chief difference is that for these three polymers the diffusion departs mildly from Fick's law at the later stages of some of the sorption and desorption experiments. This generally uncomplicated diffusion of water in these three polymers contrasts with the markedly anomalous diffusion found for organic vapors such as methanol and acetone into cellulose acetate and nitrate. With polyvinyl alcohol the diffusion of water is distinctly anomalous and closely resembles the non‐Fickian diffusion of organic vapors in cellulose acetate and nitrate. One consequence is that the rate of sorption and desorption of water in polyvinyl alcohol is considerably slower than in the other polymers and is also concent

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158009

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY

摘要:

AbstractInteresting new derivatives of nylon with unusual properties were prepared by treating nylon with ethylene oxide. These graft copolymers have greatly enhanced flexibility but still retain the high melting character of the original nylon. A hydroxyethyl 6‐6 nylon containing 50% combined ethylene oxide was found to be flexible and useful over a very large temperature range, the polymer having a melting point of 221°C. and an apparent second‐order transition point below −40°C. Analyses, carried out to study the distribution of combined ethylene oxide residues in these materials, indicated a tendency toward limited substitution of the nylon backbone and rather long average polyethylene glycol branch lengths. The distributions of the combined ethylene oxide residues are correlated with the nature of the starting materials. Synthetic methods, analyses, infrared spectra, solubilities, viscosity behavior, melting point and second‐order transition point data, stress‐elongation results, and moisture permeabilities of these materials are reported. The hydroxyethyl derivatives are more hydrophilic than the unsubstituted linear nylons. Hydroxyethyl nylon should also be considerably more stable than Type 8 nylon since it does not contain the labileN‐methoxymethyl linkage. A striking contrast in properties exists between hydroxyethyl nylon and derivatives of nylon prepared in solution under homogeneous conditions. This difference in properties is attributed to a nonrandom distribution of branch sites along the chain in the case of hydroxyethyl nylon. This nonrandomness is due to the heterogeneous nature of the ethylene oxide‐nylon reaction and to the formation of primary hydroxyl groups which are more reactive toward ethylene oxide than the original a

ISSN:0022-3832    

DOI:10.1002/pol.1955.120158010

出版商:Interscience Publishers, Inc.    

年代:1955

数据来源: WILEY