摘要:

AbstractExposure of gaseous ethyl acrylate to ultraviolet radiation causes deposition of poly(ethyl acrylate) at a rate depending on a number of parameters, including the wave‐length of the radiation, its intensity, and exposure time. The rate also depends upon the monomer pressure and the presence of contaminants, most notably moisture and oxyge

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120811

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe catalytic activity of the complexes prepared by the reaction of Grignard reagents with ketones, esters, and an epoxide as polymerization catalysts of methyl and ethyl α‐chloroacrylates was investigated. The modifiers which gave isotactic polymers were α,β‐unsaturated ketones such as benzalacetophenone, benzalacetone, dibenzalacetone, mesityl oxide, and methyl vinyl ketone, and α,β‐unsaturated esters such as ethyl cinnamate, ethyl crotonate, and methyl acrylate. Catalysts with butyl ethyl ketone, propiophenone, and propylene oxide as modifiers produced atactic polymers but no isotactic polymers. It was revealed that the complex catalysts having a structure CCOMgX (X is halogen) gave isotactic polymers. The mechanism of isotactic polymerization was discussed. In addition, for radical polymerization of ethyl α‐chloroacrylate, enthalpy and entropy differences between isotactic and syndiotactic additions were calculated to give ΔHi*− ΔHs*= 910 cal/mol

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120812

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractTwo series of linear polyesters containing isocyanurate rings have been prepared to determine the effect of structural variations on thermal and solubility properties. The polyesters were prepared by the polycondensation reaction of isocyanurate containing difunctional acid and ester monomers with linear diols. The substituent on the isocyanurate ring and the length of the acid side chain have been shown to have considerable effect on the glass transition temperatureTg. Different solubility properties were observed for the series of polyesters in which the pendant substituent was C6H5and the acid side‐chain was CH2CO2H. These polymers were insoluble in THF, and the polyester prepared from 1,6‐hexanediol was also insoluble in chloroform. Thermal gravimetric analysis (TGA) indicated that structural differences had no significant effect on the thermal stability of these linear pol

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120813

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractBy measurement of the specific volume of solutions of poly‐α‐methylstyrene in α‐methylstyrene monomer at 25°C, the dilatometric constant was found to beKD= (0.002007 ± 0.000030)%−1. Estimation of the temperature dependence resulted in the equation (KD)t= 1.81 × 10−3+ 7.82 + 10−6t, wheretdenotes t

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120814

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe polymerization of phenylacetylene and other terminal and internal alkynes has been achieved in homogeneous reactions catalyzed by ArM(CO)3, where Ar is an arene; M is Cr, Mo, or W. The polymerization of phenylacetylene proceeds by way of an intermediate which has been isolated and identified as a ladder compound composed of fused cyclobutane rings. The ladder compound, which is stable in the absence of the catalyst, breaks down in the presence of the catalyst to give the final polyconjugated polymer. Available evidence indicates that the conversion of the ladder compound to polyphenylacetylene proceeds by way of a free‐radical mechanism. A mechanism for the electronic conversion of the ladder compound to the final polymer is proposed, as is a method of chain propagatio

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120815

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe technique for determining branching in polymers by using a combination of GPC and intrinsic viscosity data has been extended beyond current methods. Equations used in these analyses are presented. The derivations are based upon the assumption that branching is present only when there is a measurable reduction in the intrinsic viscosity. Techniques for calculating the functionality of the star branch point in starbranched polymers are given. Three random‐branching parameters are calculated from a knowledge of the average branching density,\documentclass{article}\pagestyle{empty}\begin{document}$ \bar \lambda $\end{document}: (a) the lowest molecular weight branched polymer that can be measured,M̄*; (b) the average molecular weight between branch points,M̄bp; (c) the weight percentage of polymer that is branched. The applicability of this technique is demonstrated by using an analysis of published data on characterized fractions of a randomly branched polystyr

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120816

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractBranching analyses in styrene–butadiene rubbers and polybutadiene rubbers have revealed large differences in branching between rubbers polymerized in different ways. The functionalities of several star‐branched solution‐polymerized styrene–butadiene rubbers were calculated and compared to their expected structures. Emulsion‐polymerized polybutadiene rubber and a series of solution‐polymerized polybutadienes made with different catalysts had different degrees of random branching, and evidence is presented indicating that the different available catalyst systems provide some latitude in making rubbers of different branching contents. Random branching analyses on a series of emulsion‐polymerized styrene–butadiene rubbers revealed the dependency of branching on molecular weight and molecular weight distribution. The influence of polymerization temperature on the branching of emulsion‐polymerized styrene–butadiene rubb

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120817

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractPolymers containing cyano groups connected to the polymeric chain by means of at least one methylene group adsorb palladium dichloride reversibly from its slightly acidic solutions and form surface complexes of the probable structure (CH2CN)2PdCl2. These complexes can adsorb gaseous olefins; ethylene is consumed continuously, but adsorption of propylene and 1‐butene reaches saturation. Additional ethylene can be added to the propylene or 1‐butene adsorbate. Hydrolysis of the surface olefinic complexes yields aldehydes, the ethylene complex giving acetaldehyde and butanal, the mixed ethylene–1‐butene complex giving acetaldehyde, butanal

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120818

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractPhotosensitized copolymerization of optically activeN‐l‐menthylmaleimide (NMMI) with styrene (Sty) and methyl methacrylate (MMA) was carried out in tetrahydrofuran (THF) at 30°C with benzoyl peroxide (BPO). The monomer reactivity ratios for the copolymerization of NMMI (M2) with Sty (M1) and MMA (M1) werer1= 0.08 ± 0.10,r2= 0.20 ± 0.05 andr1= 2.85 ± 0.06,r2= 0.07 ± 0.06, respectively. Copoly‐MMA–NMMI and poly‐NMMI showed positive circular dichroism(CD) curves of equal intensity and shape over the wavelength region from 230 to 270 nm; copoly‐Sty–NMMI also showed a positive CD curve which was similar in shape but was different in intensity from that of poly‐NMMI. The correlation between monomer unit ellipticity of the copolymers and their composition would suggest the alternating and stereoregular copolymerizat

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120819

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

Abstract13C NMR spectra of acrylic monomers complexed with a Lewis acid were measured and their electronic structures discussed in relation to their alternating copolymerizability. The β‐carbon of acrylonitrile and methacrylonitrile showed a downfield shift due to the complex formation with the Lewis acid, while the α‐carbon showed an upfield shift and the nitrile carbon showed no significant shift. The degree of shift of olefinic carbons decreased in the following order: AlCl3>EtAlCl2>Et1.5AlCl1.5>Et2AlCl>SnCl4, EtOAlCl2>Et(EtO)AlCl, which seems to run parallel to the Lewis acidity and acid strength. On the other hand, the chemical shift of olefinic carbons of methyl acrylate, methyl methacrylate, and olefinic diesters was influenced little by complex formation with Lewis acids, whereas the carbonyl and alkoxyl carbons were deshielded significantly by the complex formation. These results are discussed in terms of electron distribution on the carbons and an alternating polymerization mech

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120820

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY