摘要:

AbstractCationic copolymerizations ofcis‐ andtrans‐propenyl ethyl ethers (PEE) with isobutenyl ethyl ether (IBEE) were carried out in methylene chloride at −78°C with the use of boron trifluoride etherate as catalyst. Monomer reactivity ratios werer1= 24.0 ± 2.4 andr2= 0.02 ± 0.02 for thecis‐PEE (M1)–IBEE (M2) system andr1= 19.1 ± 1.8 andr2= 0.04 ± 0.02 for thetrans‐PEE (M1)–IBEE (M2) system, indicative of the reactivity order:cis‐PEE>trans‐PEE ≫ IBEE. In separate experiments, these β‐methyl‐substituted vinyl ethers were allowed to react with various acetals in the presence of boron trifluoride etherate. The relative reactivities of these ethers were generally found to decrease in the order:cis‐β‐monomethylvinyl>vinyl>trans‐β‐monomethylvinyl>β,β‐dimethylvinyl. Comparisons of these results with previously published copolymerization data have permitted the conclusion that, in both the copolymerizations and acetal additions, the single β‐methyl substitution on vinyl ethers exerts little steric effect against their additions toward any alkoxycarbonium ion, whereas the β,β‐dimethyl substitution results in a large adverse steric effect toward both β‐monometh

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071101

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThe wetting properties of a series of polyacrylates containing the fluoroalkyl group\documentclass{article}\pagestyle{empty}\begin{document}$ [\rlap{--} ({\rm CF}_{\rm 2} \rlap{--} )_2 {\rm CF}_2 {\rm H}\ $\end{document}have been studied. Wherenis 7 and 9, the polyacrylates are highly crystalline at room temperature. Since the polymers were prepared under atactic free‐radical conditions and the polyacrylates with shorter alkyl groups (wherenis 3 or 5) were not crystalline at room temperature, the crystallinity is presumed to occur as a result of side‐chain packing and not involve the backbone. The polymers become more wet‐table (higher γc) as polymer crystallinity was reduced by quenching or heating pastTm. Correlations have been made between the work of Zisman and co‐workers on the wetting properties of various fluorinated acid monolayers and the wetting properties of these fluoroalkyl acrylates. The results obtained in this study concerning the influence of polymer crystallinity on surface wetting are discussed in relation to the findings of Schonhorn and Ryan on the wettability of polyethylene single crystal ag

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071102

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractVolatile products, molecular weight changes, and rates of volatilization have been examined during the thermal decomposition of poly(methyl α‐phenylacrylate) in vacuum at 210–280°C. In the early stages of the decomposition, initiation occurs at random within the polymer backbone to give radicals which unzip exclusively to monomer, with a kinetic chain length of about 500. Later in the reaction, chain‐end initiation becomes important and predominates beyond about 45% conversion. There is no evidence that transfer reactions occur during the degr

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071103

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractPolythioureas having pendant hydroxyl groups were prepared by the polyaddition reaction of bisaminoalcohols and diisothiocyanates. The polythioureas had inherent viscosities in the range of 0.22–1.08 dl/g and gave transparent films by solution casting. These polythioureas were converted to polythiazolines by treatment with poly(phosphoric acid) or to poly(thiazoline–oxazolines) by treatment with a mixture of poly(phosphoric acid) and a polar solv

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071104

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractForty polycyanurates were prepared by the interfacial polycondensation of 2‐substituted 4,6‐dichloro‐s‐triazines with various aromatic diols. Nitrobenzene was used as a solvent, aqueous sodium hydroxide as an acid acceptor, and a cationic emulsifier as an accelerator. The rate of reaction was largely increased by ultrasonic irradiation. The polymer yield was in the range 57–91%, and the reduced viscosity was 0.41–3.5. The polymers were soluble in chloroform, nitrobenzene, ando‐dichlorobenzene but insoluble in common organic solvents such as alcohol, acetone, and hydrocarbons. A clear film was obtained from the chloroform‐soluble polymers after evaporation of the solvent. The softening temperature and the thermal stability of each polycyanurate was significantly related to the substituent on thes‐triazine nucleus as well as to the diol component in the molecular chain. Polymers of favorable properties were derived from 2‐substituted 4,6‐dichloro‐s‐triazines with R = C6H5, N(C6H5)2, N(C6H11)2, N(C6H5)(SO2C6H4CH3), or carbazyl and aromatic diols such as 4,4′‐dihydroxybenzophenone, Bisphenol A, or phenolphthalein. These polymers showed tensile strength of 500–670 kg/cm2, elongation at break of 2.9–6

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071105

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThe kinetics of anionic polymerization of α‐methylstyrene have been studied in tetrahydrofuran at −30 to 10°C with Na+and K+as cations. In the Na+system, a negative activation energy of −2 kcal/mole was observed in the temperature range −10 to +10°C. The results were analyzed in terms of propagation by both contact and solvent‐separated ion‐pairs. The relative proportions of the two types of ion‐pair were estimated by making use of our data and those of Dainton et al. for the same system at −60 to −30°C. The rate constants of solvent‐separated ion‐pairs,ks, were estimated as 4.2 and 0.64 1./mole‐sec at −31°C and −59°C, respectively. The discrepancy between our values ofksand Dainton's was discussed. It is concluded that poly‐α‐methyl‐styryl sodium has a higher tendency than polystyryl sodium to form solvent‐separated ion pairs. In the K+system, our data at −30 to 10°C and those of Dainton et al. at −60 to −40°C fit well into a straight line in the same Arrhenius plot from which an activation energy of 5.2 k

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071106

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractIn order to clarify the correlation between polymerization and monomer isomerization in the monomer‐isomerization polymerization of β‐olefins, the effects of some transition metal compounds which have been known to catalyze olefin isomerizations on the polymerizations of butene‐2 and pentene‐2 with Al(C2H5)3–TiCl3or Al(C2H5)3–VCl3catalyst have been investigated. It was found that some transition metal compounds such as acetylacetonates of Fe(III), Co(II), and Cr(III) or nickel dimethylglyoxime remarkably accelerate these polymerizations with Al(C2H5)3–TiCl3catalyst at 80°C. All the polymers from butene‐2 were high molecular weight polybutene‐1. With Al(C2H5)3–VCl3catalyst, which polymerizes α‐olefins but does not catalyze polymerization of β‐olefins, no monomer‐isomerization polymerizations of butene‐2 and pentene‐2 were observed. When Fe(III) acetylacetonate was added to this catalyst system, however, polymerization occurred. These results strongly indicate that two independent active centers for the olefin isomerization and the polymerizations of α‐olefins were necessary for the monomer‐isom

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071107

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractA study of the isomerization of butene‐2 with TiCl3or Al(C2H5)3–TiCl3catalyst inn‐heptane has been investigated at 60–80°C to elucidate further the mechanism of monomer‐isomerization polymerization. It was found that positional and geometrical isomerizations in the presence of these catalysts occurred concurrently with activation energies of 14–16 kcal/mole. The presence of Al(C2H5)3with TiCl3catalyst could accelerate the initial rates of these isomerizations and initiate the monomer‐isomerization polymerization of butene‐2. From the results obtained, it was concluded that the isomerization of butene‐2 proceeds via an intermediate σ‐complex between the transition metal hydri

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071108

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractTo elucidate the propagation mechanism in the cationic polymerization of vinyl ethers and β‐substituted vinyl ethers, the electron distribution in these monomers was computed by the extended Hückel method. Propylene and styrene derivatives were also studied in comparison with the vinyl ether derivatives. Attempts were made to explain the experimental results by various calculated reactivity indices. With the unsaturated hydrocarbons, the reactivity indices on the β‐carbon parallel with the relative reactivity in the cationic polymerization or oligomerization. This agreement suggests that the transition state for the rate‐determining step of the propagation reaction is represented by a model in which the carbonium ion interacts with the β‐carbon of a monomer. On the other hand, the effect of β‐alkyl or alkoxyl groups on the reactivity of vinyl ethers could not be explained by the model in which the carbonium ion interacts with an olefinic carbon or an ether oxygen, or both with two atoms. The following model was proposed on the basis of the electronic stabilization energy due to the de‐localization from the occupied orbital of a monomer to the vacant orbital of a carbonium ion. This model can explain reasonably the relative reactivity of vinyl ethers and β‐substituted vinyl ethers observed in the cationic copolymerization cataly

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071109

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY

摘要:

AbstractThe anomalous crystalline transition of methacrylic acid found by broad‐line NMR measurements was studied in connection with the build‐up and decay of trapped radicals. The build‐up of radicals is smaller and the decay rate of the trapped radicals is faster in the low‐temperature range (phase II), which gave the narrower maximum slope distance ΔHmslof the NMR spectrum, than those in the higher temperature range (phase I), which gave the broader ΔHmsl. From these experiments it was concluded that in phase I the crystals have a more closely packed structure, resulting in a more rigid matrix for the trapped radicals than those in phase II. This interpretation is consistent with the temperature dependence of the ESR spectrum of the trapped propagating radicals previously reported. The existence of the crystalline transition was also confirmed by DSC measurements, and the effects of the crystallization conditions on the transition were investigated and were discussed with reference to the results of broad line NMR mea

ISSN:0449-296X    

DOI:10.1002/pol.1969.150071110

出版商:John Wiley&Sons, Inc.    

年代:1969

数据来源: WILEY