摘要:

AbstractThe hypothesis ofHarwoodandPatel, suggesting for the polymerization of 2‐phenyl‐1,3,2‐dioxaphospholane a type of insertion reaction to explain the formation of ethylenediphosphinic ester structures besides the normal 2‐hydroxyethyl(phenyl)phosphonic ester structures is extended to similar monomers and its theoretical consequences are examined. It is shown that in such a system mutual transformations between ω‐hydroxyalkyl‐P‐acid and alkylenedi(P‐acid)structures should occur, establishing a dynamic equilibrium and leading to a sort of azeotropic polymer, in which only one unique composition is kinetically stable. Equations relating to different kinetic parame

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781201

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractOptimized syntheses of 1,3,6,9‐tetraoxacycloundecane (2), 1,3,6,9,12‐pentaoxacylotetradecane (3), and 1,3,6,9,12,14,17,20‐octaoxacyclodocosane (4) as well as some physical and chemical properties and the proof of structure are rep

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781202

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractChitin was deacetylated by heterogeneous and homogeneous alkaline hydrolyses. In the heterogeneous hydrolysis, upper limits in the degree of deacetylation were found to exist at low reaction temperatures. The products obtained were all insoluble in water and those with a degree of deacetylation up to 80% retained some crystallinity. These results seemed to indicate that the deacetylation under the heterogeneous conditions proceeded preferentially in the amorphous region to give block‐type copolymers ofN‐acetyle‐D‐glucosamine and D‐glucosamine units. In the homogeneous hydrolysis, on the other hand, all the products with a degree of deacetylation of ca. 50% were found to be soluble in water independent of the hydrolysis temperature. The crystallinity of the products decreased much more rapidly and samples with a degree of deacetylation>40% were amorphous. These results suggested that the deacetylation under homogeneous conditions proceeded randomly to give the random‐type copolymers of the two units. This randomness was concluded to have brought about the interesting water‐solubility of products with a degree of deacetylati

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781203

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractThe activated anionic polymerization of 2‐pyrrolidone (1a) was studied by usingN‐potassium‐2‐pyrrolidone (1e) as initiator in a 1:1 mole ratio withN‐acetyl‐ (1b),N‐benzoyl‐ (1c), andN‐pivaloyl‐2‐pyrrolidone (1d),N‐benzoyl‐8‐octanelactam (2a) orN‐benzoyl‐12‐dodecanelactam (2b) as activators in the heterogeneous stage of the polymerization pr

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781204

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

Abstract4‐(1,3‐Dimethyl‐2,6‐dioxo‐2,6‐dihydropurin‐7‐yl)‐3‐hydroxybutyric acid (4a) and 4‐(6‐amino‐9‐purinyl)‐3‐hydroxybutyric acid (4b) were synthesized through the addition reaction of theophylline or adenine, respectively, to 1‐chloro‐2,3‐epoxypropane followed by cyanization and acidic hydrolysis. Condensation polymerization of4awas carried out using dicyclohexylcarbodiimide, 2,4,6‐triisopropylbenzenesulfonyl chloride orp‐toluenesulfonyl chloride as dehydrating agents in dimethylformamide or pyridine. The oligoester of4awas obtained as a white powder with a molecular weight>700

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781205

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractThe polymerization of methyl methacrylate initiated by ferric salt and thiourea in dimethyl sulfoxide solution was studied. By the substitution of hydrogen by an alkyl or aryl group in the thiourea, the rate of the polymerization decreases. The logarithm of the rate is proportional to the σ*value of Taft's equation. The results are discussed on the basis of the IR and NMR data. It was confirmed that the polymerization is initiated by a radical produced by the reaction of the ferric ion with the isothiourea which is formed from the thiourea by tautomerization. The termination of the polymerization is also discussed based on the results of kinetic studies with different kinds and concentrations of the ferric salt

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781206

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractN,N‐Dimethylaniline (DMA) does initiate the free‐radical polymerization of methyl methacrylate (MMA), methyl acrylate, and methyl vinyl ketone. The overall rates of polymerization of MMA were obtained at 40, 50, and 60°C. From the results of a detailed kinetic investigation, the activation enthalpy and activation entropy of polymerization were calculated as 63,2 kJ mol−1and −153 J mol−1K−1at 60°C. Rate equation was also obtained asRp=k[DMA]1/2[MMA]3/2and the polymerization was inhibited by benzoquinone. Though styrene alone was not polymerized by DMA, the copolymerization of MMA with styrene by DMA (reactivity ratios:rMMA=0,45 andrSt=0,50) followed a typical free‐radical mechanism. An electron‐transfer complex between DMA and MMA is proposed as the i

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781207

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractValues of the unperturbed dimensions of poly(2‐hydroxyethyl methacrylate) have been determined in five non‐ideal solvents using viscometric data and a number of different theoretical treatments. Values of the steric factor σ, the characteristic ratioC∞and the expansion factor α were also calculated. There was some variation of all these parameters with solvent but on the whole they were comparable to values for polymethacrylates with non‐polar side groups of a sim

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781208

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

摘要:

AbstractUsing a new general formulation of Flory's gelation criterion, a critical transition equation is derived for the trimethylolpropane (2,2‐bis(hydroxymethyl)‐1‐butanol)/adipic acid/lauric acid system having a substitution effect on the hydroxyl groups of the triol. The successive reactivity of the hydroxyl groups present in the trimethylolpropane has been formulated by the study of the condensation of the triol with the monoacid, lauric acid. From GPC measurements of the reaction medium for various degrees of conversion, the distribution curves of the different molecular species are plotted. Examination of these distribution curves has shown a non‐equireactivity of the sites of the polyol, which may be assigned to a positive substitution effect. Comparison of experimental distribution curves with the results of the kinetic analysis allows one to quantify the substitution effect. The gelation equation shows that a positive substitution effect on the hydroxyl groups of the triol decreases the extent of reaction necessary for the gelation. The difference between the experimental gelation curves and the theoretical curves with substitution effect may be assigned to intramolecular re

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781209

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY

ISSN:0025-116X    

DOI:10.1002/macp.1977.021781210

出版商:Hüthig&Wepf Verlag    

年代:1977

数据来源: WILEY