A series of measurements of Hall effect, thermoelectric power and electrical conductivity have been performed on the vitreous CdGexAs2 having a Ge content of 0.2, 0.3, 0.4, 0.6 and 1 mol respectively. The electrical conductivity has an exponential behaviour in the temperature range 185–500 K only for the 0.6 and 1 mol composition. It deviates from the exponential behaviour at lower temperatures for the 0.2, 0.3 and 0.4 compositions. The thermoelectric power is positive for CdGe0.2As2, negative for CdGe0.6As2 and CdGe1.0As2, whereas it changes sign for CdGe0.3As2 and CdGe0.4As2. The Hall coefficient is negative for alll compositions except for the CdGe1.0As2. The Hall mobilities differ widely for the different compositions and have the values of 1.5 × 10–2 to 1.3 × 10–1 cm2 V–1 s–1 at room temperature.
{"title":"Hall effect, thermoelectric power and electrical conductivity measurements in vitreous CdGexAs2","authors":"R. Callaerts, M. Denayer, F. Hashmi, P. Nagels","doi":"10.1039/DF9705000027","DOIUrl":"https://doi.org/10.1039/DF9705000027","url":null,"abstract":"A series of measurements of Hall effect, thermoelectric power and electrical conductivity have been performed on the vitreous CdGexAs2 having a Ge content of 0.2, 0.3, 0.4, 0.6 and 1 mol respectively. The electrical conductivity has an exponential behaviour in the temperature range 185–500 K only for the 0.6 and 1 mol composition. It deviates from the exponential behaviour at lower temperatures for the 0.2, 0.3 and 0.4 compositions. The thermoelectric power is positive for CdGe0.2As2, negative for CdGe0.6As2 and CdGe1.0As2, whereas it changes sign for CdGe0.3As2 and CdGe0.4As2. The Hall coefficient is negative for alll compositions except for the CdGe1.0As2. The Hall mobilities differ widely for the different compositions and have the values of 1.5 × 10–2 to 1.3 × 10–1 cm2 V–1 s–1 at room temperature.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"1 1","pages":"27-34"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76770818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The energy spectra of monochromatic neutrons scattered on selenium and telllurium have been investigated by means of a rotating crystal spectrometer. In polycrystalline selenium the highest spectral line can be identified as an intrachain bond stretching mode. Transforming selenium from its crystalline to its amorphous and liquid state, the shift of the line energy is only a few percent. The other lines in the spectra (from bond shearing and torsional modes of the chains) are influenced more strongly. For tellurium, on the other hand, the spectral lines of the solid disappear completely in the liquid phase. The experimental results are compared with the results of optical spectroscopy. Furthermore, the diffusive motion of the atoms has been studied by quasi-elastic neutron scattering for liquid selenium containing various admixtures of iodine (0–6 %), which change the average chain length of the polymeric melt, and for liquid tellurium. For Se, one obtains an effective diffusion constant D which describes the motion of small chain segments over atomistic distances. D is of the order of 10–5 cm2/s. Its activation energy was about 5 Kcal/mol.
{"title":"The investigation of atomic motions in crystalline, amorphous and liquid selenium, and in crystalline and liquid tellurium by neutron spectroscopy","authors":"A. Axmann, W. Gissler, A. Kollmar, T. Springer","doi":"10.1039/DF9705000074","DOIUrl":"https://doi.org/10.1039/DF9705000074","url":null,"abstract":"The energy spectra of monochromatic neutrons scattered on selenium and telllurium have been investigated by means of a rotating crystal spectrometer. In polycrystalline selenium the highest spectral line can be identified as an intrachain bond stretching mode. Transforming selenium from its crystalline to its amorphous and liquid state, the shift of the line energy is only a few percent. The other lines in the spectra (from bond shearing and torsional modes of the chains) are influenced more strongly. For tellurium, on the other hand, the spectral lines of the solid disappear completely in the liquid phase. The experimental results are compared with the results of optical spectroscopy. Furthermore, the diffusive motion of the atoms has been studied by quasi-elastic neutron scattering for liquid selenium containing various admixtures of iodine (0–6 %), which change the average chain length of the polymeric melt, and for liquid tellurium. For Se, one obtains an effective diffusion constant D which describes the motion of small chain segments over atomistic distances. D is of the order of 10–5 cm2/s. Its activation energy was about 5 Kcal/mol.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"84 1","pages":"74-81"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82305298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dielectric and viscoelastic measurements have been made on dilute solutions of poly(butylisocyanate). The measurements confirm that the molecules are predominantly rod-like in hydrodynamic behaviour. The end-over-end rotation times obtained from both sets of observations have been analyzed by three methods. The monomer projection length along the major axis cannot be evaluated independently of the value chosen for the length-to-thickness ratio, but it is probably less than 1.1 A and greater than 0.6 A. Application of the Kratky-Porod model to molecules for which the chain length is less than the persistence length must be treated with caution. For poly(butylisocyanate) the persistence length obtained from dilute solutions is 230 monomer units, although extrapolation of a wider concentration range to infinite dilution yields a value of 400 monomer units. Concentration has a marked effect on chain stiffness parameters (increasing apparent cylinder radii or decreasing persistence lengths) which is explained in terms of side-by-side dipole association.The dielectric measurements of Phillips 4 made on a variety of samples of poly(N-vinyl carbazole) have been analyzed using equations suitable for rod-like or stiff-coil polymers. For molecular weights above 50,000 the molecules are coil-like with a Kratky-Porod persistence length of 250 monomer units. Shorter chains are rod-like in which the projection length of each monomer unit along the rod is roughly ⅔ the monomer length. This suggests that the short chains (8-20 monomer units) adopt a semicircular are outline. Both polymers show increasing departures (in both the dielectric and the viscoelastic parameters) from rod-like behaviour as the temperature is raised. The change is continuous through room temperature so that there is no reason for assigning a perfect structure (helical or otherwise) to solutions at these temperatures. The experimental data do not, generally, allow sensible treatment using number average molecular weights, so that weight (or perhaps even higher) averages must be used for heterodisperse samples.
{"title":"Dielectric and viscoelastic relaxation in dilute solutions of some non-Gaussian chains","authors":"S. Dev, R. Lochhead, A. North","doi":"10.1039/DF9704900244","DOIUrl":"https://doi.org/10.1039/DF9704900244","url":null,"abstract":"Dielectric and viscoelastic measurements have been made on dilute solutions of poly(butylisocyanate). The measurements confirm that the molecules are predominantly rod-like in hydrodynamic behaviour. The end-over-end rotation times obtained from both sets of observations have been analyzed by three methods. The monomer projection length along the major axis cannot be evaluated independently of the value chosen for the length-to-thickness ratio, but it is probably less than 1.1 A and greater than 0.6 A. Application of the Kratky-Porod model to molecules for which the chain length is less than the persistence length must be treated with caution. For poly(butylisocyanate) the persistence length obtained from dilute solutions is 230 monomer units, although extrapolation of a wider concentration range to infinite dilution yields a value of 400 monomer units. Concentration has a marked effect on chain stiffness parameters (increasing apparent cylinder radii or decreasing persistence lengths) which is explained in terms of side-by-side dipole association.The dielectric measurements of Phillips 4 made on a variety of samples of poly(N-vinyl carbazole) have been analyzed using equations suitable for rod-like or stiff-coil polymers. For molecular weights above 50,000 the molecules are coil-like with a Kratky-Porod persistence length of 250 monomer units. Shorter chains are rod-like in which the projection length of each monomer unit along the rod is roughly ⅔ the monomer length. This suggests that the short chains (8-20 monomer units) adopt a semicircular are outline. Both polymers show increasing departures (in both the dielectric and the viscoelastic parameters) from rod-like behaviour as the temperature is raised. The change is continuous through room temperature so that there is no reason for assigning a perfect structure (helical or otherwise) to solutions at these temperatures. The experimental data do not, generally, allow sensible treatment using number average molecular weights, so that weight (or perhaps even higher) averages must be used for heterodisperse samples.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"90 1","pages":"244-256"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82144688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A laser homodyne spectrometer has been used to study the power spectrum of light scattered from dilute polystyrene + 2-butanone solutions. From the measurements the translational diffusion constants for the macromolecules were determined as a function of molecular weight and solute concentration. The analysis of the data included an estimation of the unperturbed dimensions of the polymer.
{"title":"Rayleigh scattering from polystyrene solutions","authors":"N. Ford, F. E. Karasz, J. Owen","doi":"10.1039/DF9704900228","DOIUrl":"https://doi.org/10.1039/DF9704900228","url":null,"abstract":"A laser homodyne spectrometer has been used to study the power spectrum of light scattered from dilute polystyrene + 2-butanone solutions. From the measurements the translational diffusion constants for the macromolecules were determined as a function of molecular weight and solute concentration. The analysis of the data included an estimation of the unperturbed dimensions of the polymer.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"54 1","pages":"228-237"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88511120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nuclear magnetic relaxation helps in unfolding the pattern of molecular motion in polymer solutions. Information on both solvent and polymer motions can be obtained by appropriate experiments. Examples are given using T1 and T2 measurements on polyethylene oxide, polydimethylsiloxane, polyisobutylene and other systems. Several general features appear in nuclear relaxation of the polymer molecules. T1 is insensitive to the molecular weight of the polymer and to the concentration of the solution up to about 20 % concentration. T1 depends on solvent viscosity though the variation appears to be less pronounced than that predicted by Bloembergen-Purcell-Pound theory. T2, on the other hand, is a function of polymer concentration, and drops rapidly with concentration at high molecular weights. This is in accord with what is known about entanglements in polymer solutions. T1 and T2 are not changed by replacing hydrogen-containing solvents with deuterated substitutes. The rate of solvent motion is too rapid to be effective in nuclear relaxation of the polymer. T 1 and T2 measurements on the solvent in polymer solutions can be analyzed in detail by selective replacement of hydrogen by deuterium. This has been done in the poly(methylmethacrylate)+ benzene system. An apparent anomaly of solvent T2 in solutions of high molecular weight polymer is explained in terms of a fluctuating chemical shift.
{"title":"Nuclear magnetic relaxation in polymer solutions","authors":"J. Anderson, Kang‐Jen Liu, R. Ullman","doi":"10.1039/DF9704900257","DOIUrl":"https://doi.org/10.1039/DF9704900257","url":null,"abstract":"Nuclear magnetic relaxation helps in unfolding the pattern of molecular motion in polymer solutions. Information on both solvent and polymer motions can be obtained by appropriate experiments. Examples are given using T1 and T2 measurements on polyethylene oxide, polydimethylsiloxane, polyisobutylene and other systems. Several general features appear in nuclear relaxation of the polymer molecules. T1 is insensitive to the molecular weight of the polymer and to the concentration of the solution up to about 20 % concentration. T1 depends on solvent viscosity though the variation appears to be less pronounced than that predicted by Bloembergen-Purcell-Pound theory. T2, on the other hand, is a function of polymer concentration, and drops rapidly with concentration at high molecular weights. This is in accord with what is known about entanglements in polymer solutions. T1 and T2 are not changed by replacing hydrogen-containing solvents with deuterated substitutes. The rate of solvent motion is too rapid to be effective in nuclear relaxation of the polymer. T 1 and T2 measurements on the solvent in polymer solutions can be analyzed in detail by selective replacement of hydrogen by deuterium. This has been done in the poly(methylmethacrylate)+ benzene system. An apparent anomaly of solvent T2 in solutions of high molecular weight polymer is explained in terms of a fluctuating chemical shift.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"34 1","pages":"257-267"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89937237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The enthalpies of mixing at infinite dilution have been measured for the four systems polyisobutylene + benzene, +n-pentane, +n-hexane and +n-octane from room temperature up to the vicinity of the lower critical solution temperatures. The results are analyzed in terms of the statistical theories of polymer solutions due to Prigogine and to Flory. Both theories give a reasonable qualitative description of the experimental results.
{"title":"Thermodynamic properties of some polymer solutions at elevated temperatures","authors":"A. Liddell, F. L. Swinton","doi":"10.1039/DF9704900115","DOIUrl":"https://doi.org/10.1039/DF9704900115","url":null,"abstract":"The enthalpies of mixing at infinite dilution have been measured for the four systems polyisobutylene + benzene, +n-pentane, +n-hexane and +n-octane from room temperature up to the vicinity of the lower critical solution temperatures. The results are analyzed in terms of the statistical theories of polymer solutions due to Prigogine and to Flory. Both theories give a reasonable qualitative description of the experimental results.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"5 1","pages":"115-120"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87611350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inelastic cold neutron scattering experiments have been carried out on polycrystalline (hexagonal) and vitreous GeO2. Coherence effects are observed for both materials for ω [graphic omitted] 300 cm–1 and it has been possible to estimate the approximate form of two average acoustic branches of the spectrum for the polycrystal. For the glass the coherence effects may be interpreted in terms of wave vector conservation conditions operating in a similar manner to that in polycrystals. The approximate shape of two average acoustic branches has been estimated together with the frequency of a further branch near the equivalent of the Brillouin zone boundary. The data have also been examined on the basis of the incoherent approximation to determine the main features of the frequency distribution G(ω) for the glass at ω < 600 cm–1, in which region the most prominent peak is near 300 cm–1.The low frequency peaks in G(ω) account extremely welll for the low temperature heat capacity. The neutron scattering results have been compared with the infra-red and Raman spectra of vitreous GeO2 showing that the relation between G(ω) and the spectra is different in each case but that the infra-red absorption coefficient probably approximates reasonably well to G(ω), except below about 200 cm–1. A comparison has also been made with a theoretical frequency distribution for a model of vitreous GeO2. The neutron spectra for the glass show a peak at 13 cm–1, estimated to contain about 0.05 % of the total modes and attributed to resonance modes associated with some particular, but so far unidentified, structural defects.
{"title":"Vibrational properties of vitreous germania by inelastic cold neutron scattering","authors":"A. Leadbetter, D. Litchinsky","doi":"10.1039/DF9705000062","DOIUrl":"https://doi.org/10.1039/DF9705000062","url":null,"abstract":"Inelastic cold neutron scattering experiments have been carried out on polycrystalline (hexagonal) and vitreous GeO2. Coherence effects are observed for both materials for ω [graphic omitted] 300 cm–1 and it has been possible to estimate the approximate form of two average acoustic branches of the spectrum for the polycrystal. For the glass the coherence effects may be interpreted in terms of wave vector conservation conditions operating in a similar manner to that in polycrystals. The approximate shape of two average acoustic branches has been estimated together with the frequency of a further branch near the equivalent of the Brillouin zone boundary. The data have also been examined on the basis of the incoherent approximation to determine the main features of the frequency distribution G(ω) for the glass at ω < 600 cm–1, in which region the most prominent peak is near 300 cm–1.The low frequency peaks in G(ω) account extremely welll for the low temperature heat capacity. The neutron scattering results have been compared with the infra-red and Raman spectra of vitreous GeO2 showing that the relation between G(ω) and the spectra is different in each case but that the infra-red absorption coefficient probably approximates reasonably well to G(ω), except below about 200 cm–1. A comparison has also been made with a theoretical frequency distribution for a model of vitreous GeO2. The neutron spectra for the glass show a peak at 13 cm–1, estimated to contain about 0.05 % of the total modes and attributed to resonance modes associated with some particular, but so far unidentified, structural defects.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"11 1","pages":"62-73"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82472785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The van der Waals equation of state, in spite of its oversimplifications, gives useful qualitative information about mixtures over a wide range of temperatures and pressures. When the Bronsted principle of congruence is used to evaluate the parameter a12 for the mixture, a wide range of properties can be predicted: excess functions (including temperature and composition dependence) and phase equilibria (including lower critical solution phenomena at high temperatures), in good qualitative agreement with experimental properties of mixtures of n-alkanes.
{"title":"Static properties of solutions. Van der Waals and related models for hydrocarbon mixtures","authors":"R. Scott, P. V. Konynenburg","doi":"10.1039/DF9704900087","DOIUrl":"https://doi.org/10.1039/DF9704900087","url":null,"abstract":"The van der Waals equation of state, in spite of its oversimplifications, gives useful qualitative information about mixtures over a wide range of temperatures and pressures. When the Bronsted principle of congruence is used to evaluate the parameter a12 for the mixture, a wide range of properties can be predicted: excess functions (including temperature and composition dependence) and phase equilibria (including lower critical solution phenomena at high temperatures), in good qualitative agreement with experimental properties of mixtures of n-alkanes.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"6 1","pages":"87-97"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81031597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The normal and the anomalous diffusion in binary polymer solutions are considered. After a survey of the theory of diffusion it is demonstrated which criteria must be fulfilled so that the Fickian diffusion occurs. For transport between the solvent and a solution, or between two solutions, normal diffusion is found. Experimental results with polystyrene + solvent systems are given. With good solvents the diffusion coefficient increases strongly with increasing polymer concentration, passes through a maximum at medium concentrations and decreases by several decades at high polymer concentrations. This concentration dependence arises because the diffusion coefficient is not only a transport coefficient, but also contains a thermodynamic factor. With poor solvents, which show a phase separation of the polymer at low temperatures, the concentration dependence of the diffusion coefficient is even more complicated. With increasing concentration of polymer the diffusion coefficient first decreases, passes through a minimum and the increases again. In this case there is also a maximum at medium concentrations and a strong decrease at high polymer concentrations. The minimum for a binary system is located at the critical point of the system.Normally ln D is a linear function of 1/T. Deviations from the linear course can be explained by the temperature dependence of the thermodynamic factor.For anomalous diffusion the √t-relations are no longer valid, since the diffusion coefficient depends not only on concentration, but also explicitly on time. The anomalous diffusion is due to the fact that superimposed on the normal diffusion is another process. If a solvent penetrates into a glassy polymer, then relaxation processes are superimposed on the diffusion process. The polymer changes from the glassy state into a state of internal thermodynamic equilibrium. Experimentally the continuous range between the pure glassy polymer and the pure solvent can be divided into three parts of an open system. In the first and the third part only diffusion occurs, while in the second part diffusion and structural relaxation are superimposed.
{"title":"Fickian and non-Fickian diffusion in high polymer systems","authors":"G. Rehage, O. Ernst, J. Fuhrmann","doi":"10.1039/DF9704900208","DOIUrl":"https://doi.org/10.1039/DF9704900208","url":null,"abstract":"The normal and the anomalous diffusion in binary polymer solutions are considered. After a survey of the theory of diffusion it is demonstrated which criteria must be fulfilled so that the Fickian diffusion occurs. For transport between the solvent and a solution, or between two solutions, normal diffusion is found. Experimental results with polystyrene + solvent systems are given. With good solvents the diffusion coefficient increases strongly with increasing polymer concentration, passes through a maximum at medium concentrations and decreases by several decades at high polymer concentrations. This concentration dependence arises because the diffusion coefficient is not only a transport coefficient, but also contains a thermodynamic factor. With poor solvents, which show a phase separation of the polymer at low temperatures, the concentration dependence of the diffusion coefficient is even more complicated. With increasing concentration of polymer the diffusion coefficient first decreases, passes through a minimum and the increases again. In this case there is also a maximum at medium concentrations and a strong decrease at high polymer concentrations. The minimum for a binary system is located at the critical point of the system.Normally ln D is a linear function of 1/T. Deviations from the linear course can be explained by the temperature dependence of the thermodynamic factor.For anomalous diffusion the √t-relations are no longer valid, since the diffusion coefficient depends not only on concentration, but also explicitly on time. The anomalous diffusion is due to the fact that superimposed on the normal diffusion is another process. If a solvent penetrates into a glassy polymer, then relaxation processes are superimposed on the diffusion process. The polymer changes from the glassy state into a state of internal thermodynamic equilibrium. Experimentally the continuous range between the pure glassy polymer and the pure solvent can be divided into three parts of an open system. In the first and the third part only diffusion occurs, while in the second part diffusion and structural relaxation are superimposed.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"42 1","pages":"208-221"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79325240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The method of small angle scattering of polarized light permits one to investigate fast processes of ordering of polymer solutions in the course of crystallization, and in particular, to study the kinetics of spherulite growth. The registration velocity of the scattering patterns was not lower than 2 photos s–1, the exposure did not exceed ½ s, and the range of the size registered was from a fraction of a micron to several microns. This method was used for studying the temperature dependence of the spherulite growth rate during isothermal crystallization of polypropylene solutions in decalin in the absence of the “kinetic memory” effect. The growth rate followed fairly closely the general thermodynamic relationships. Crystallization of the polypropylene solution in decalin carried out with stretching of the jet leads to the growth of spherulites flattened with respect to the stretching direction. When the take-up velocity grows, the flattening of the spherulites increases and their radius decreases. A general formal explanation is given of the phenomenon of the flattening of the spherulites in the course of their growth in a mechanical field and of the peculiarities of the supermolecular order formation during molecular orientation.
{"title":"Small angle light scattering by ordered polymer solutions","authors":"V. G. Baranov","doi":"10.1039/DF9704900137","DOIUrl":"https://doi.org/10.1039/DF9704900137","url":null,"abstract":"The method of small angle scattering of polarized light permits one to investigate fast processes of ordering of polymer solutions in the course of crystallization, and in particular, to study the kinetics of spherulite growth. The registration velocity of the scattering patterns was not lower than 2 photos s–1, the exposure did not exceed ½ s, and the range of the size registered was from a fraction of a micron to several microns. This method was used for studying the temperature dependence of the spherulite growth rate during isothermal crystallization of polypropylene solutions in decalin in the absence of the “kinetic memory” effect. The growth rate followed fairly closely the general thermodynamic relationships. Crystallization of the polypropylene solution in decalin carried out with stretching of the jet leads to the growth of spherulites flattened with respect to the stretching direction. When the take-up velocity grows, the flattening of the spherulites increases and their radius decreases. A general formal explanation is given of the phenomenon of the flattening of the spherulites in the course of their growth in a mechanical field and of the peculiarities of the supermolecular order formation during molecular orientation.","PeriodicalId":11262,"journal":{"name":"Discussions of The Faraday Society","volume":"22 1","pages":"137-143"},"PeriodicalIF":0.0,"publicationDate":"1970-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88107920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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