摘要:

AbstractA method for the first synthesis of high molecular weight carbonate‐containing siloxanylene polymers was successfully developed. The procedure covered the preparation and polymerization of pure carbonate‐containing bis‐silanols which included bis(4‐hydroxydimethylsilylphenyl)‐carbonate, bis[4‐(1‐hydroxy‐1,1,3,3‐tetramethyldisiloxanyl)‐phenyl] carbonate, and their meta analogs. Because conventional siloxane polymerization methods, such as the heterocondensation of bis‐silanols with diaminosilanes or homocondensation reactions catalyzed by alkali reagents, decomposed carbonate linkages, a new polymerization technique that involved the use of phosgene was used. The procedure was both facile and effective in the polymerization of other

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200101

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractWith high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) films the grafting reactions were performed by the preirradiation method. By holding the total absorption dose constant irradiation time was varied. The initial rate of grafting decreased with irradiation time. The relative concentration of alkyl radical in the polyethylene film also decreased with irradiation time, but the relative concentration of allyl increased. The differences in the ESR spectrum before and after the introduction of styrene indicate that the allyl‐type radical reacted with styrene. To elucidate these results the allyl radical in the amorphous region was consi

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200102

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics of thermal degradation of a sample of 46.0% isotactic polyvinyl bromide (PVBr) was studied in a static procedure. An integrated analytical method is presented for the estimation of rate constants. Reaction curves for the formation of hydrogen bromide (HBr) can be interpreted in terms of two concurrent first‐order reactions; namely,with activation energies of 29.7 and 40.6 kcal/mol, respectively. The mathematical derivation does not involve an approximation; thus the accuracy of the procedure depends only on the experimentation. Good agreement between calculated and experimentally determined values of a series of characteristic kinetical parameters was obtained. The formation of HBr from PVBr was studied kinetically by a thermogravimetric programmed procedure at room temperature to 700°C. By this method it is possible to determine the activation energy of the stripping process of the main chain without knowing the form of the kinetic equation. The activation energy of 40.1 kcal/mol for the overall process was evaluated by the MacCallum and Tanner method. This dynamic heating developed two distinct temperature regions in which maximum rate loss occurred at characteristic temperatures. The first temperature region was associated with the quantitative evolution of 100% HBr molecul

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200103

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe first confirmed synthesis of methylene malonamide (MeMal) is reported. This monomer was prepared by the thermal elimination or fluoride‐ion‐initiated elimination of trimethylsilyl chloride from α‐chloro‐α(trimethylsilyl‐2‐methyl) malonamide. Spectral data for the monomer are given. MeMal has been shown to be unstable in a variety of protic organic solvents, including water and alcohols, thus giving the appropriate (α‐methyl) substituted malonamides. MeMal is stable in most

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200104

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractEfforts have been made to prepare perfect terminally functional linear telechelic polyisobutylenes with various Lewis acid coinitiators, BCl3, AlCl3, TiCl4, SnCl4, VCl4, and SbCl5. However, the expected desirable results (F̄n= 2.0,M̄w/M̄n= 1.5) were obtained only with BCl3. Moreover, the concentration of BCl3affects the molecular weight of telechelic polyisobutylenes prepared by the inifer technique. The Kennedy–Smith inifer mechanism is insufficient to explain these observations. Extending this model by the concept of counteranion stability, of Heublein et al.,5and assuming the participation of free ions and ion pairs in propagation and termination, led to a satisfactory mechanistic model. The exceptional utility of the BCl3/BCl⊖system is due to the high Lewis acid strength of BCl3and low counteranion stability o

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200105

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractVinyl polymerization of acrylonitrile initiated by the Ce(IV)/thioacetamide redox system has been investigated in aqueous sulfuric acid in the temperature range of 10–20°C. The rate of polymerization (Rp) and the rate of Ce(IV) disappearance (−RCe) were measured. The effect of certain water‐soluble organic solvents, added electrolytes, and aromatic and heterocyclic organic nitrogen compounds on the rate of polymerization has been investigated. Depending on the experimental results, we have suggested a suitable reaction scheme for the system which involves the production of initiating radicals from the oxidation of thioacetamide (TAm) by ceric ion and the termination of the polymer chain by meta

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200106

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractA new electronodonor monomer,N,N‐dimethyl‐p‐aminobenzyl methacrylate (DMABM), was synthesized and radical copolymerized with two electronoacceptor monomers, acryloyl‐ (DNBA) and methacryloyl‐(DNBM) β‐hydroxyethyl‐3,5‐dinitrobenzoate, in order to obtain intramolecular charge‐transfer‐complex copolymers. Also, the small‐molecular models of poly(DMABM), poly(DNBA), and poly(DNBM), the respective acetates, were synthesized and used to measure the values of ionization potentialIpof the donor and the electronic affinityEaof the acceptor. They areIp= 7.15 eV andEa= 1.41 eV. The lower value ofIpas compared with that of carbazole derivatives is taken as evidence of a nonterminal mechanism of copolymerization. Also, from the1H‐NMR and electronic spectra, the intramolecular complexation is discussed in terms of total transfer of the electron from donor to a

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200107

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe photoinitiation efficiency of the free‐radical polymerization of methyl methacrylate and styrene by several carbonly compounds has been determined. The compounds considered were α‐substituted ketones and α‐dicarbonyl compounds. For the ketones, the initiation efficiency employing methyl methacrylate depends on the α substitution; the values obtained change from less than 10−3(acetone) to 0.65 (3‐hydroxy‐3‐methyl‐2‐butanone). All ketones are more efficient towards methyl methacrylate than styrene. This result can be explained in terms of triplet quenching by the last monomer. The results obtained employing α‐dicarbonyl compounds do not conform to a simple pattern. In particular, benzil shows a considerably larger efficiency towards styrene than for methyl methacrylate. Since benzil is efficiently quenched by styrene, the initiation must involve the interaction of an excited benzil m

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200108

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

Abstract4,4′‐Diaminobenzanilide (DAB) was reacted with diacids via the Yamazaki phosphorylation reaction to yield simple polyamides and random copolyamides. The use of DAB was found to promote polycondensation because DAB contains a preformed amide linkage which minimizes the amounts of by‐products formed. It also maximizes polymer solubility since the monomer is unsymmetrical. The order of the inherent viscosity values of the polymers obtained from DAB by reaction with different diacids, isophthalic>aliphatic>terephthalic, was found to parallel polymer solubility in the reaction medium. The inherent viscosity of the polyamide based on terephthalic acid, DAB‐T, was increased greatly by copolymerization, isophthalic acid being more effective than an aliphatic diacid in this regard. None of the polymers formed a thermotropic nematic phase, but the copolymer having an equimolar ratio of terephthalic and adipic acid formed anisotropic solutions in 100% sulfuric acid at polymer concentrations exceeding 40%. Strong films were cast from such so

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200109

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe evolution of HCN from the oxidation of nylon 66 has been studied in three apparatuses of different design (all based on stream flow) over a temperature range from 390 to 700°C. Although the numerical values for rate constants (diffusion controlled) and energies of activation differ, the same mechanism is deduced from the results of the three designs. It is concluded that a simple horizontal tube in a furnace is the most efficient apparatus as far as sweeping out volatile products is concerned. The mechanism of thermal oxidative degradation has been evaluated in detail. It is shown that mechanisms where the first reaction step is not the slowest or the slowest one of first or second order all fit the experimental results. However, it is concluded that the mechanism where the first step is first order and the slowest one is the most likely one. The respective parameters have been evaluated for the results obtained from the horizontal tube apparatus

ISSN:0360-6376    

DOI:10.1002/pol.1982.170200110

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY