摘要:

AbstractThe nature of the acceleration period which is found in the polymerisation ofexo‐2‐methyl‐7‐oxabicyclo‐[2.2.1]‐heptane with FeCl3—SOCl2, when R = [FeCl3]/[SOCl2] is above a certain limit, has been investigated. By means of a conductometric study of the reactions occurring in C2H4Cl2/diethylether mixture (6:1 by volume), between FeCl3and SOCl2, it has been possible to show that this acceleration period is related to a slow formation of ionic species, from which the chain carriers are formed.When the catalyst/cocatalyst mixture was allowed to stand until equilibrium was attained before it was added to the monomer solution, no acceleration period was detectable.The kinetic study of the polymerisation was then extended to the whole range of catalyst/cocatalyst ratios. It has been shown that the ion SO2⊕which is present when [FeCl3] is higher than [SOCl2] is not able to initiate the polymerisation. If R is ⪖ 5 there is no polymerisation, whatever the [FeCl3]. If R is less than 5 but more than about 2, the polymerisation practically stops at partial conversion. When R is well below 1 the time‐conversion curves give good second order plots indicating a station

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280101

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractMeasurements of intrinsic viscosity in decalin at 135°C and light scattering in α‐chloronaphthalene at 145°C were performed for several polypropylene fractions of molecular weight ranging up to 2.106. The specific refractive index increment at 436 mμ for the α‐chloronaphthalene solution was found to be −0.231 ml/g, which is considerably higher than those reported by CHIANGand others authors. However, no significant disparity is observed between the results of light scattering measurements by CHIANGand the present author. The intrinsic viscosity‐molecular weight relationship obtained is: [η] = 1.15·10−4M W0.799, which is in good agreement with that reported by KINSINGERand HUGHES. This relationship is also compared with those of other authors observed at different conditions of visc

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280102

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractEthyl vinyl sulfide (EVS) and phenyl vinyl sulfide (PVS) were found to undergo alternative copolymerization with maleic anhydride (MAn) even in the absence of radical initiators. It is noted that both the rates and the reduced viscosities in these alternative copolymerization show a maximum at 50 mole‐% comonomer mixture, anticipating that a 1 : 1 charge transfer complex is formed preceding polymerization. From spectroscopic studies, it was also observed that the formation of such a complex between vinyl sulfide and MAn was confirmed, but their equilibrium constants were quite small,i.e.0.090 l./mole for PVS‐MAn in CHCl3and 0.035 l./mole for EVS‐MAn in CH2Cl2at room temperature. The mechanism of these alternative copolymerizations is disc

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280103

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractPolymerization of styrene was carried out in presence of polyethers at 30°C in benzene solution using borontrifluoride etherate as a catalyst. The polymerization was retarded in the presence of polyethylene oxide. At the same time, the degradation of polyethylene oxide and chain transfer reaction were found to undergo under our conditions.The chain transfer constants of polyethers were determined and the contribution of each functional group of the chain was estimated

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280104

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractA method of preparation of a lattice‐disordered (or amorphous) zinc dimethoxide was explored, involving the reaction of diethylzinc with methanol under reflux in methanol solution. The amorphous zinc dimethoxide thus obtained, showed extremely high activity for propylene oxide polymerization. This polymerization is of living type and follows a first order rate law for the disappearance of monomer. The activity of the amorphous zinc dialkoxide decreases in the presence of ethylzinc alkoxide or alcohol. On change of solvent, the polymerization rate is found to depend on coordination strength of solvent, rather than on its dielectric constant. Polymerization of propylene oxide catalyzed by the diethylzinc/alcohol system is discussed in terms of a coordinate anionic mechanis

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280105

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractIn order to pursue the possibility of the extended chain crystals of polymers formed in the course of polymerization, the cationic polymerization of trioxane in cyclohexane has been studied. The polymer, polyoxymethylene, was obtained in the form of a unique single crystal. From the morphological and physical studies of the resultant polymers as well as the kinetical studies of the polymerization, it has been revealed that long, needle‐like nuclei formed in the beginning of the polymerization grew into feather‐like platelets with twin habit. The degree of crystallinity of the nascent polymer was essentially 100% in terms of their densities. The molecular chains were fully extended and regularly aligned in the direction of the crystal growth. The growth of the crystal occurred as the polymerization proceeded. Thus it is considered that the crystal grows quite successively to the propagation of the chains through direct addition of the monomer molecules onto the reactive chain ends which are aligned two‐dimensionally on the growing surface of the crystal. The molecular length of the nascent polymer estimated from the solution viscosity, however, did not agree with the crystal dimensions measured in the direction of the molecular orientation, the former being rather small. The above results are explained in terms of the chain‐transfer reaction and the catalytic decomposition of the polyme

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280106

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractThe persulphate‐bisulphite‐Cu2⊕initiated emulsion polymerization of vinyl chloride has been investigated in the presence of a metal‐ion complexing agent (trisodiumcitrate). In the range of concentrations investigated, the rate of radical production from the redox system was found to be 2nd order with respect to the concentration of NaHSO3and independent of the persulphate concentration. The effect of the concentrations of citrate and copper ions was found to be strongly dependent on the ratio [citrate]t/[Cu]t(index t indicating total added amounts). In borax and phosphate buffer, the rate of polymerization was found to be proportional to [Cu]t1/4·[citrate]−1/2at ratios larger than about ten. When the ratio approaches unity, an abrupt increase in rate was observed. A kinetic scheme based on the equilibrium reaction\documentclass{article}\pagestyle{empty}\begin{document}$$ 2\ {\rm Cu}^{2 \oplus } + 2\ {\rm OH}^{\rm \ominus } + 2\ {\rm citrate}^{3\ominus }\mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} {\rm Cu}_2({\rm OH})_2 ({\rm citrate)}_2^{{\rm 4\ominus }}$$\end{document}is discussed. The effects of [Cu]tand [citrate]t, as predicted by this scheme, were calculated by computing numerical values of [Cu2⊕] according to the above equilibrium. This proved the theory to be in good agreement with the experime

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280107

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractBei geeigneter Auswertung kann man bei Lichtstreuungsmessungen an hochpolymerer Desoxyribonuclein‐Säure eine Feinstruktur beobachten, die als Folge eines „Superknäuels”︁ gedeutet werden kann. Die quantitative Auswertung nach der Theorie von PTITZYNführt bei nativer Lachsspermien‐DNS auf einen Superknäuel, der aus 14 Helixzylindern von jeweils 1060 Å Länge besteht; diese sind durch gelockerte Gebiete verbunden. Durch Vergleich mit dem totalen Molekulargewicht kann der Denaturierungsgrad e

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280108

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractThe method proposed by DEBand CHATTERJEE1for the determination of unperturbed dimension of a polymer from solution viscosity data in different solvents and molecular weight has been applied to four fractions of polystyrene in a series of cosolvents consisting of varying amounts of acetone and cyclohexane. The solubility characteristics of these cosolvents, particularly the optimum solvent composition, have been examined with respect to the thermodynamic theory of R. L. SCOTT.

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280109

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY

摘要:

AbstractNew observations on the thermal polymerization of pure styrene at 130°C refute an earlier claim by MÜLLERthat 1‐phenyltetralin is the major dimeric product. The principal dimeric products arecis‐ andtrans‐1.2‐diphenylcyclobutane in a 1:2 ratio with relatively minor amounts of 1‐phenyltetralin, 1.3‐diphenylbutene, and 1‐phenyl‐1.2‐dihydronaphthalene. Data are also given for the dimers formed at 85°C and for the dimers isolated from a fully cured (180°C) polystyrene the significance of differences in minor constituent yields is assessed. MAYO's basic postulate of radical pair production by reaction of a DIELS‐ALDERtype dimer with styrene is the starting point for a more extended reaction scheme in which cage reactions form minor dimeric and trimeric products in compeßiti

ISSN:0025-116X    

DOI:10.1002/macp.1969.021280110

出版商:Hüthig&Wepf Verlag    

年代:1969

数据来源: WILEY