摘要:

AbstractIn order to elucidate the mechanism of radiation‐induced polymerization of methyl methacrylate adsorbed on silica gel, the effects ofp‐benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited byp‐benzoquinone at levels above 10‐2mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease asp‐benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected byp‐benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose‐rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in format

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140201

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractTwo samples of cellulose (molecular weight 2.97 × 105and 1.25 × 105) were transformed into carbanilates (CTC) which were then fractionated by the elution method at a constant composition of the acetone‐water elution mixture with the column temperature gradually increasing from −30°C to 30°C, and by the GPC method in acetone and tetrahydrofuran. Tetrahydrofuran appeared to be a more suitable solvent. The molecular weights of fractions obtained by the elution fractionation were determined by the light‐scattering method in tetrahydrofuran. The width of fractions was determined by the GPC method (averageMw/Mn= 1.37); the [η] values and the Mark‐Houwink constants (K= 5.3 × 10‐3,a= 0.84) for tetrahydrofuran at 25°C were determined. The calibration curve for the GP method was constructed by means of the fractions thus obtained; it was demonstrated that the universal calibration curve according to Benoit can also be used. It was demonstrated that the molecular weight distribution of cellulose can be conveniently determined by conversion into CTC followed either by the elution fractionation (for preparative purposes) or by fractionation by the GPC method (for anal

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140202

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractA series of polypropionamide‐ureas was synthesized by the polymerization ofN‐mesyloxysuccinimide with diamines in polar aprotic solvents in the presence of acid acceptors. The polymerization proceeded through the formation of ring‐opened adducts, followed by elimination and rearrangement yielding β‐isocyanatopropionamide derivatives, which in turn were polymerized to afford polypropionamide‐ureas. These polymers had inherent viscosities in the range of 0.1–0.2. Polymers having aliphatic chains which were fusible below 240°C were soluble in acidic solvents, whereas those with aromatic residues dissolved in polar aprotic solvents. Marked decomposition of the polyamide‐ureas under thermogravimetric analysis generally occurred at around 320°

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140203

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe alternating copolymerization of methyl methacrylate with styrene with the use of stannic chloride was kinetically examined at −20°C in 1,2‐dichloroethane both under photoirradiation and with radical initiator (2:1 tri‐n‐butylboron‐benzoyl peroxide system). At conversions lower than 7%, the conversion increases linearly to the polymerization time, whereas the degree of polymerization is constant irrespective of the polymerization time. The alternating copolymerizations are 1.5 order and the 1.0 order reactions with respect to the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The linear dependences of the rates upon the 0.5 order of the intensity of the incident light and upon the 1.0 order of the concentration of tri‐n‐butylboron indicate a bimolecular termination. The rate normalized by the 1.5 order of the concentration of the coordinated methyl methacrylate and the rate normalized by the concentration of the coordinated methyl methacrylate are proportional to the 1.5 and 1.0 orders of the charged concentration of styrene, for the copolymerizations under photoirradiation and with initiator, respectively. The kinetic results in the 1,2‐dichloroethane solution are quite consistent with those in the toluene solution. The alternating copolymerization mechanism, in which the ternary molecular complex predominantly homopolymerizes as a monomer un

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140204

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractAromatic diketones of the benzophenone type undergo photopolymerization on irradiation at 350 nm with tetramethylallene in benzene solution. The polymers produced contain oxetane units in the main chain, and spectroscopic analysis demonstrates that the distribution of structural units parallels that found in the reaction between benzophenone and tetramethylallene. The polymers are rapidly degraded thermally and by mineral acids.

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140205

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractAttempts to photopolymerize 1:1 mixtures of furan and aromatic diketones of the benzophenone type by irradiation of benzene solutions at 350 nm were unsuccessful. An alternative route via furan‐diketone 2:1 adducts was more successful but was complicated by the intervention of hydrogen abstraction reactions in competition with oxetane formation, leading to crosslinking and insolubilization in some case

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140206

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of polyelectrolytes on the reaction of methylene blue with 1‐benzyl‐1,4‐dihydronicotinamide was investigated. An accelerating effect was observed on addition of sodium polystyrenesulfonate of poly(potassiump‐styrenesulfonate). On the other hand, deceleration was observed on addition of potassium polyvinylsulfate. No appreciable effect was observed when sodiump‐toluenesulfonate or potassium chloride was used as an electrolyte. An obvious color change was observed when methylene blue is bound to these anionic polyelectrolytes. Some correlations with spectral change of methylene blue and acceleration or deceleration effect are

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140207

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe degradation of films containing both PS and PVC has been examined by TVA and TG. Stabilization of both polymers, more notably PS, is observed, but the degradation products are the same as when the polymers are degraded alone. Molecular weight measurements indicate a more rapid decrease in the molecular weight of PS when PVC is present. The possibility of grafting or other processes leading to chlorine incorporation in PS has been excluded by the results of experiments using36Cl‐labeled PVC. The mechanisms of possible interactions between the degrading polymers are discussed. Processes involving reaction of chlorine radicals with PS at lower temperatures and reaction of PS radicals with the residue of PVC dehydrochlorination or its decomposition products at higher temperatures appear probabl

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140208

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe use of the Williamson reaction to prepare polyfluoroethers, [OArOCH2(CF2)3CH2]nfrom 1,1,5,5‐tetrahydryl‐F‐1,5‐pentanediol and polyfluoroaromatic and polyfluoroheteroaromatic compounds was investigated. Fluorine NMR spectroscopy was used to determine the structures of the resultant polymers.F‐Biphenyl and 1,5‐bis(F‐2‐pyridyloxy)‐1,1,5,5‐tetrahydryl‐F‐pentane (BPFP) afforded the polymers where Ar is 4,4′‐C6F4C6F4andrespectively. The polymer prepared fromF‐pyridine differed from that obtained from BPFP in that it had an irregular structure and contained 2,4′‐ as well as 2,2′ ‐ and 4,4′‐linked rings.F‐Benzene, 4‐(1,1‐dihydryl‐F‐butoxy)‐F‐pyridine, andF‐pyrimidine each gave materials having copolymer structures. The inherent viscosities of the polymers depended on the polyfluorocyclic compound used and ranged from 0.05 to 0.2 dl/g. The heterocyclic polymers were elastomeric. The polymers fromF‐pyridine and BPFP had the lowest glass transition temperatures (∼−10°C), and started to lose weight (by

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140209

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractIn an alkyllithium‐initiated polymerization of butadiene or styrene, dialkylzinc complexed with the initiator and effectively increased the initiation rate. This is particularly true with initiator of low solubility due to its very high state of aggregation. Dialkylzinc also complexes with the aggregated polymer‐lithium molecules to give a lower apparent solution viscosity. In the presence of a base such as tetrahydrofuran, diethylzinc served as chain‐transfer

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140210

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY