摘要:

AbstractEs werden nach verschiedenen Methoden Kristallisationsversuche an isotaktischen Polystyrolen unterschiedlichen Molekulargewichts durchgeführt. Gemische von isotaktischen und ataktischen Polystyrolen werden mit verschiedenen Kristallisationsmedien behandelt und die abgetrennten kristallisierten isotaktischen Anteile durch RÖNTGENdiagramme und Schmelzpunkte charakterisiert.Einige durch Polymerisation von Styrol mit n‐Amylnatrium hergestellte Polystyrole werden nach der Fällungsmethode fraktioniert. Die Verteilung der Polymerisationsgrade ist sehr breit. Die hochmolekularen Polystyrolfraktionen sind durchweg gut kristallisierbar und weisen relativ hohe Taktizität auf, während sehr niedermolekulare Fraktionen aus ataktischen Polystyrolen bestehen. Im mittleren Molekulargewichtsbereich (10 000–20 000) liegen mit großer Wahrscheinlichkeit Mischungen aus ataktischen und isotaktischen Polystyrolen vor, die mit den bekannten Methoden nicht getrennt werd

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650101

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe electric dipole moments of 7 samples of poly(ethylene glycols) (POEG) carefully fractioned with molecular weights ranging from 194 to 7770 have been measured at 25 ± 0.05°C. in benzene solution, by a W.T.W. beat‐apparatus working at the frequency of 2 megacycles per second. The dielectric cell has been calibrated by 16 nitrobenzene and chlorobenzene solutions in benzene at 25°C.The orientation polarizations of POEG at zero concentration have been obtained by the simplified GUGGENHEIMprocedure, and the electric dipole moments by the DEBYE equation. The mean probable error in the experimentally determined dipole moments is not superior to 1 per cent.From these values the specific polar moments μsp= (μ2/χ)1/2(the average moments per monomer unit) have been calculated. The plot of μspagainst μ is not consistent with the hypothesis of the free rotation, but it agrees with the statistically calculated values of μspassuming that the rotations of the elementar bond dipoles are hindered by a potential barrier asymmetric around the “trans” conformation.The excluded volume effect for dipole moments of dissolved POEG is briefly discussed, the suggestion being made to perform dipole measurements at the FLORYΘ‐temperature on a wider range of

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650102

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractDurch Kondensation von Fluoren mit D‐Glucose oder Cellulose in flüssigem Fluorwasserstoff wird ein hochpolymeres Produkt erhalten, das die Komponenten mit CC‐Bindungen verknüpft enthält. Die D‐Glucosereste liegen in offenkettiger Form vor (5 acetylierbare Hydroxylgruppen pro D‐

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650103

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractSwelling measurements with natural rubber, polydimethylsiloxane, hydropolybutadiene and polyurethane were made using a large number of liquids. The solubility parameters of these polymers were calculated, using the method suggested by GEE. A critical appraisal of the previous work on swelling has been reported. It is concluded that in view of the unsatisfactory position of the theory of solution, choice of solvents is very important while trying to estimate solubility parameter of the polymer from such comparative studies as swelling measurement etc.

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650104

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe cohesive energy densities (c.e.d.) of a number of polyacrylates and polymethacrylates have been estimated by swelling measurements in a series of alkyl esters. It is seen that the magnitudes of c.e.d. for polyacrylates are higher than those for polymethacrylates and in a homologous series, c.e.d. decreases with increase in the length of the alcoholic chain.

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650105

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractEquations are derived which permit the calculation of number and weight average degrees of polymerization for the low and high molecular weight fractions obtained by dichotomy of the molecular weight distribution, at any chosen molecular size, of a polymer having the “most probable” type of distribution. An approximate treatment is also given which is satisfactory for almost all purpo

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650106

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractPolyesteramides have been prepared by interfacial condensation of hexamethylene glycol‐1,6‐bis(4‐chlorocarbonylbenzoate) and various alkylenediamines. The melting points of these polyesteramides are compared with samples prepared previously by melt condensation of bisesteramides and gl

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650107

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractIt was found that hetero‐cyclic compounds of high polymerizability, active halogen compounds and water increased the catalytic activity of aluminum alkyl for the polymerizations of 3,3‐bis(chloromethyl)oxacyclobutane (BCMO) and tetrahydrofuran (THF). Based upon the assumption that aluminum alkyl is a LEWIS acid, the behavior of these effective additives were interpreted in terms of cationic polymerization mechanism. It was proposed to define the first group of the additives,e.g., epichlorohydrin and propylene oxide as promoter, the second one,e.g., acetyl chloride and α‐chlorodimethyl ether as cocatalyst and water as modifier. Ternary systems consisting of triethylaluminum, water and promoter or cocatalyst were found to be much more active, some of which induced the polymerization of BCMO at −78°C. and that of T

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650108

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe intensities of the infrared absorption band at 916 cm−1have been measured for various polyvinyl alcohol samples of different tacticities. A close relation has been discovered between the band intensity and syndiotactic structure. It is proposed that this band provides a measure of syndiotacticity in polyvinyl alcoho

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650109

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY

摘要:

AbstractThe steric structure of polyvinyl formate prepared by the solid state polymerization has been investigated. From the X‐ray and infrared spectra and solubility of the polymer, a stereoblock structure was proposed.A sharp reflection at d = 4.10 Å in the X‐ray spectrum of the polymer seems to correspond to (220) reflection which is the strongest reflection in the spectrum of isotactic polyvinyl formate. This indicates that the length of the isotactic sequence in the polymer is long enough to be able to form an order detectable with X‐ray diffraction. The results of the examination on polyvinyl alcohol derived therefrom also support the view of stereoblock structure. Undoubtedly the spatial arrangement of vinyl formate in the crystalline state plays an important role to the stereoregu

ISSN:0025-116X    

DOI:10.1002/macp.1963.020650110

出版商:Hüthig&Wepf Verlag    

年代:1963

数据来源: WILEY