ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713201

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe physical feature of the G‐F transformation of action caused by a small amount of magnesium ions was investigated by measuring flow birefringence, light scattering, viscosity, and sedimentation of action solutions at various concentrations of actin and magnesium ions. All experimental results indicate that the G‐F transformation of actin can be regarded as a reversible fibrous condensation. When the concentration of actin is increased at a constant concentration of magnesium ions, fibrous aggregates of actin molecules, F‐actins, can be formed only above a critical actin concentration which is determined by the condition of medium and decreases rapidly with increasing concentration of magnesium ions. Above the critical concentration, all of the excess active actin molecules are transformed into F‐actins. These F‐actins are coexisting with active (G‐)actin molecules, the concentration of which is independent of the concentration of F‐actin and equal to the concentration of active actin at the critical point. The state of apparent units of F‐actins in solution is also determined by the condition of medium and independent of the concentration. With increasing concentration of magnesium ions, the apparent units of F‐actin become longer and longer and their thickness increases. Small globular aggregates are always observed below the critical point of formation of long fibrous aggregates. These experimental results show qualitative agreement with theoretical results obtained by one of the authors on fibrous and globular aggregations of charg

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713202

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA modification of the way of sealing a Zimm‐Myerson osmometer is described. It is shown that the improved instrument gives more accurate and more reproducible results than the one described originall

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713203

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe high polymerization of ethylene and propylene is studied by a novel catalyst which consists of metals and metal halides. Titanium halides with metallic aluminum, magnesium, or zinc are able to accelerate the polymerization of ethylene to produce a high polymer at 50‐250°C. and under the pressure of 1‐200 atoms. In the presence of metallic aluminum, the activity of titanium halides descreases with the valency of titanium. The effect of milling of metals in titanium halide solution is also studied. This treatment is found to lower the rate of reaction. An extremely high molecular polyethylene is synthetized by an appropriately chosen mixed halides catalyst. Polyethylene produced has melting point ranging from 120‐135°C., molecular weight being as high as some hundreds of thousand. Tensile strength is 100‐250 kg./cm.,2specific gravity is 0.94‐0.95. The number of CH3groups as well as of CC double bonds in small and crystallinity is considerably higher than high pressure polyethylene. This catalyst is also applied to the polymerization of propylene. A solid polypropylene melting at 140‐155

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713204

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA novel high polymerization of ethylene by Al‐TiCl4catalyst is studied. The polymer yield increases with higher TiCl4concentration and with larger amount of Al metal used. With an Al/TiCl4mole ratio larger than 10, the conversion slightly decreases. The highest conversion is gained at 180°C., and higher reaction temperatures decrease remarkably the yield of solid polymer. The molecular wight of polymers increases with the Al/TiCl4ratio, but it remains constant at Al/TiCl4ratios larger than 3. It is highest at 180°C. With respect to the Al/TiCl4mole ratio, the melting point has a relation similar to that of the molecular weight. It is also maximum at 180°C. The rate equation is determined by some kinetic studies, obtaining the formula ‐dP/dt= 4.37 [TiCl4] exp{‐4800/RT}Pfor a certain range of reaction conditions. A possible cationic mechanism for this polymerization is s

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713205

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractData are presented for copolymer composition as a function of monomer composition in the system styrene‐methyl methacrylate initiated by lithium in tetrahydrofuran and hydrocarbons. The data are interpreted in the light of the electron exchange initiation and ion‐radical propagation mechanisms previously proposed. Revisedr1andr2values for strictly anionic copolymerization of styrene and methyl methacrylate are presented on the basis of data obtained with the use ofn‐butyllithium and phenylsodium as typical anionic initiators in hydrocarbons. Sodium dissolved in liquid ammonia and sodium dispersion in hydrocarbons gave results identical with those obtained with true anionic catalysts. This is in sharp distinction to the results obtained with li

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713206

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractBy measuring the capacity change of ethyl cellulose inn‐butyl acetate solutions and determining the frequency at which the dielectric dispersion is 0.50, the same general dependence of the intrinsic viscosity on the critical frequency was found as has already been reported for solutions in other solvents. The difficulty in measuring capacities for solutions of high dissipation factor could be overcome either by using a special resistance network with the bridge, or by inserting large values of capacity in parallel with the bridge arms. The latter procedure appears to offer possibilities for use with solvents of still higher dielectric constant and is being investigated at present in this laborator

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713207

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractSimultaneous measurements of the activity coefficients of counter‐ and by‐ions in polyelectrolyte solutions were carried out. Sodium polyvinyl alcohol sulfate was used as the sample of polyelectrolyte and sodium chloride as the extraneous salt. The activity coefficient of sodium counter‐ion was determined by using a sodium amalgam electrode and that of chloride ion was determined by a sliver‐silver chloride elctrode. It was found that the activity coefficient of both counter‐ and by‐ions has little relationship with the volume of polymer coil, and that the additivity of counter‐ion activity found for hydrogen ion by Mock and Marshall holds also for sodium ion. It was also found that there is good agreement between the experimental results and the theory of Katchalsky and Lifson if we use their same theory for calculating the volume of polymer coil, although the volume is too large to be consider

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713208

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractThe infrared spectra of oriented films of valonia cellulose and of ramie and bacterial cellulose crystallites have been observed in the 3 μ region. Polarization properties of the bands have also been determined. The differences between the polarized spectra of bacterial and ramie crystallites in this region are attributed to per cent crystallinity and orientation effects. Two new bands in the CH stretching region have been observed. With this new information the CH2symmetric and antlisymmetric stretching modes are assigned to parallel and perpendicular bands, respectively, requiring a specific orientation of the CH2OH group. From the observed polarization of the bands in the OH stretching region, a system of hydrogen bonding in the crystal structure of cellulose I is proposed. This involves a change in conformation of the cellobiose unit to permit an intramolecular hydrogen bond between the C3hydroxyl and the ring oxygen of contiguous glucose units. Two sets of intermolecular hydrogen bonds are proposed: in the 101 plane the C6hydroxyls of the antiparallel chains are joined to the bridge oxygens of the adjacent parallel chains; in the 101 plane the C6hydroxyls of the parallel chains are hydrogen‐bonded to the bridge oxygens of the adjacent antiparallel chai

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713209

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY

摘要:

AbstractA general kinetic analysis of the polymerization of a monomer in the presence of a pre‐formed polymer having chain transfer sites of high activity is presented. Equations are given predicting both the grafting efficiency and the molecular weights of interest. Most of the results are expressed in terms of definite integrals which, except for special values of C8, require numerical evaluation. In most cases, approximate closed form equations can be used. The results are expressed in terms of the polymerization constants of the monomer, the initial rate of polymerization, the fractional conversion to polymer, and the decrease in the concentration of transfer site

ISSN:0022-3832    

DOI:10.1002/pol.1959.1203713210

出版商:Interscience Publishers, Inc.    

年代:1959

数据来源: WILEY