摘要:

A far ultraviolet study showed progressive bathochromic wavelength shifts within the following series of compounds: (i) allyltrimethylsilane, diallyldimethylsilane, triallylmethylsilane, tetraallylsilane; (ii) allyltripropylsilane, diallyldipropylsilane, triallylpropylsilane; (iii) 4,4-dimethyl-1-pentene, 4,4-dimethyl-1,6-heptadiene, 4-allyl-4-methyl-1,6-heptadiene. In the series tri-methylvinylsilane, dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane, trimethylvinylsilane was shifted bathochromically from the rest of the vinylsilanes, which were grouped together. Allyldimethylvinylsilane showed two independent absorptions.

ISSN:0022-233X    

DOI:10.1080/10601326908051916

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A number of unsaturated silanes which are functionally capable of polymerizing by the cyclopolymerization mechanism have been synthesized and their polymerization studied. Allyl-substituted silanes studied include diallylmethylphenylsilane, diallylcyclotetramethylenesilane, and diallylcyclopentamethylenesilane. The latter two compounds have been characterized, and their physical properties are reported since they are new structures. Methallyl-substituted silanes studied include dimethallyldimethylsilane, dimethallyldiphenylsilane, dimethallylmethylphenylsilane, and dimethallylcyclopentamethylenesilane. The latter compound has been characterized, and its physical properties are reported since it is a new structure. Also, allylvinyldimethylsilane was prepared, characterized, and studied, since this compound is functionally capable of producing a five-membered ring in the repeating unit of the polymer. All of the diallylsilanes yielded polymers of low molecular weight by use of coordination catalysts of the Ziegler type. The dimethallylsilanes failed to yield polymer via coordination initiators but yielded low polymers by a free radical machanism. Allylvinyldimethylsilane yielded a low, noncyclic polymer via coordination initiation in which only the allyl double bond participated. By the free radical mechanism, polymers of similar structure were obtained.

ISSN:0022-233X    

DOI:10.1080/10601326908051917

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The monomer reactivity ratios for the copolymerizations of p-isopropylstyrene with styrene and with methyl methacrylate have been determined by the ionization chamber-vibrating reed electrometer radioactivity assay technique. The values from the differential form of the copolymerization equation are r1(styrene) = 1.22, r2(p-isopropylstyrene) = 0.89, and r1(methyl methacrylate) = 0.44, r2(p-isopropylstyrene) = 0.39. The values from the integrated form of the equation are r1(styrene) = 1.37 and r2= 0.99. These values indicate that, in the copolymerization of p-divinylbenzene (p-DVB) with styrene, the p-isopropylstyrene-like unit, formed from having the first vinyl group of p-DVB reacted, takes part in subsequent propagation reactions with styrene less readily than either styrene or p-DVB.

ISSN:0022-233X    

DOI:10.1080/10601326908051918

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The monomer reactivity ratios for vinyl acetate (VAc)-allilidene diacetate (ADA) copolymerization have never been obtained. The composition of VAc-ADA copolymers was determined by NMR spectroscopy, measuring CH protons corresponding to ADA at 3.1τ and VAc at 5.1τ. The monomer reactivity ratios were evaluated; r1= 1.34 ± 0.05 and r2= 0.48 ± 0.03, where M1= ADA and M2= VAc. From these values the Q and e values for ADA were calculated: Q = 0.047 and e = 0.44 by taking Q = 0.026 and e = −0.22 for VAc. The H value [1] for copolymerization of ADA, VAc, and vinyl chloride (VC) is 0.87.

ISSN:0022-233X    

DOI:10.1080/10601326908051919

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The rate constant of decomposition of p-methoxy-p′-nitrobenzoyl peroxide (MN-BPO), k′d, in various monosubstituted benzenes was measured. The value of k′dseemed to increase with the polarity of the solvents. Activation energies and activation entropies of the decomposition were determined. When styrene was present, the rate constant of decomposition of MN-BPO, kd, increased markedly by three to five times, except in the case of cyano-and nitrobenzenes.

ISSN:0022-233X    

DOI:10.1080/10601326908051920

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The mechanism of cationic styrene polymerization with the AlEt2Cl/RCl (R = alkyl or aryl) catalyst-cocatalyst system has been investigated. Polymerization initiation, i.e., cocatalyst efficiency, is apparently determined by the relative stability and/or concentration of the initiating carbonium ions provided by the cocatalyst RCl. Whereas n-butyl, isopropyl, and sec-butyl chlorides exhibit low cocatalyst efficiencies because of low ion concentrations, triphenyl methyl chloride is a poor cocatalyst because the stability of the derivative triphenyl methyl ion is much higher than that of the propagating styryl ion. Alkyl halides that give ions of intermediate stability are efficient cocatalysts. Isobutyl chloride and benzyl chloride seem to be exceptions and the reasons for this are discussed. A general simple scheme of the polymerization mechanism is proposed.

ISSN:0022-233X    

DOI:10.1080/10601326908051921

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The polymerization of styrene with the cationic initiator system AlR2Cl/RCl was investigated further. Earlier conclusions [1] were corroborated and expanded by an analysis of the number and weight average molecular weights. Alkyl halides with low (high) R‒Cl bond dissociation energies are efficient (poor) coinitiators of the polymerization of styrene. In the presence of efficient RCl coinitiators, the molecular weights strongly decrease and the molecular weight distributions strongly increase with increasing conversions (Fig. 1). With poor cointiators, only low conversions are obtained even in the presence of large amounts of AlEt2Cl. The data are discussed in terms of a previously proposed mechanism [1].

ISSN:0022-233X    

DOI:10.1080/10601326908051922

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The cyclopolymerization of isoprene was readily effected with the stable carbonium ion salts C7H7+SbCl6−and (C6H5)3C+SbCl6−in nitrobenzene. Little or no polymerization occurred when n-heptane, benzene, toluene, acetonitrile, methylene chloride, or nitromethane were used as reaction media. The molecular weights of the polymers obtained by light-scattering were in the range of 6,000–70,000 although the intrinsic viscosities in benzene were extremely low, i.e., 0.03–0.06. Triphenylmethyl groups were detected in cyclopolyisoprene prepared with (C6H5)3C+SbCl6−as catalyst. No tropylium residues were detected in polymers prepared with C7H7+SbCl6−. All polymers contained 10–45% unsaturation (trans-1,4 and 3,4). The unsaturation decreased with increasing trityl ion concentration but was independent of tropylium ton concentration. At constant isoprene concentration, a limiting conversion was reached; polymerization resumed on the addition of monomer. SbCl5in nitrobenzene was an effective catalyst for the cyclopolymerization of isoprene in the absence of cocatalyst. The proposed initiation mechanism involves the formation of a catalyst-nitrobenzene charge transfer complex which undergoes a one-electron transfer with isoprene monomer to yield a monomer cation-radical. The latter generates a fused ring structure by success ive cation and radical additions to monomer, as proposed for cyclopolymerizations initiated by C2H5AICl2and C2H5AlCl2-TiC14.

ISSN:0022-233X    

DOI:10.1080/10601326908051923

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

A series of condensation polymer intermediates, which included several new compositions, was prepared from 5-t-butyl-m-xylene(I)so that the effect of the bulky t-butyl group on polymer properties could be determined. Compound(I)was oxidized with nitric acid to obtain 5-t-butyl-isophthalic acid(II), which was converted successively to the diacid chloride, the diamide, the dinitrile, and finally to 5-t-butyl-m-xylene-α,α′-diamine(VI); the overall yield was 80%. The dimethyl ester of(II)was prepared and converted to 5-t-butyl-m-xylene-α,α′-diol(VIII), a new composition, in 79.5% overall yield; the diphenyl ester was also prepared. The sodium salt of(II)was catalytically reduced to obtain 5-t-butyl-1,3-cyclohexanedicarboxylic acid(IIa)in 95% yield.(IIa)was converted successively to the diacid chloride, the diamide, the dinitrile, and finally to 5-t-butyl-1,3-cyclohexanebis(methylamine)(VIa), a new composition; the overall yield was 37%.(IIa)was also converted to the dimethyl ester and finally to 5-t-butyl-1,3-cyclohexanedimethanol(VIIIa), a new composition; the overall yield was 64%. Condensation polymers were prepared from the intermediates(II),(IIa),(VI),(VIa),(VIII), and(VIIIa). These polymers had higher glass transition temperatures (Tg) than corresponding polymers containing no t-butyl groups. This general effect of the t-butyl group to increase the Tgvalue of the polymer was noted in all polymers prepared, regardless of whether the intermediate carrying the t-butyl group was a diacid, a diol, or a diamine, or whether the polymer was a polyamide, a polyester, or a polyurethane.

ISSN:0022-233X    

DOI:10.1080/10601326908051924

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

m-Bisaccharin and a number of its derivatives have been synthesized. Structural assignments were based on elemental and infrared analyses and, where appropriate, neutralization equivalents and thermal gravimetric analysis.

ISSN:0022-233X    

DOI:10.1080/10601326908051925

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor