摘要:

AbstractThe motion of each polymeric radical during a collision between the polymeric radicals with the same radius is treated as completely random motion. The result obtained is:kt= 0.250ks(wherektis the chain‐termination rate constant andksis the reaction rate constant between radical chain ends). On taking the motion of the primary radical during a collision between a primary radical and a large polymeric radical to be completely random, the result obtained is:kti= 0.250ksi(wherektiis the primary radical termination rate constant andksiis the reaction rate constant between primary radical and radical chain end). On substitutingksforksiin the second equation, the rate constant obtained becomes the chain termination rate constant between the very small polymeric radical and the very large polymeric radical, and identical to the former equation. This identity indicates that the effect of the difference of the size of the polymeric radicals on the collision process relating to the chain termination rate constant should not be larg

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090301

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe solid‐state polymerization of acrylamide, potassium acrylate, and calcium acrylate by ultraviolet radiation have been investigated. For these polycrystalline monomers both in‐source and post‐irradiation reactions were studied by using various sources of different intensities at constant temperatures. It is concluded that the polymerization reactions take place primarily on the surfaces of crystals. The high molecular weight material obtained at low conversions show a rapid decrease in intrinsic viscosities, probably due to degradation. Both the rate and degree of polymerization were decreased by the presence of oxygen. The various behaviors observed for these three monomers under ultraviolet radiation were regarded as another indication of the importance of crystal structures upon the solid‐state polymerization re

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090302

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractSeparations of carboxy‐polybutadienes and hydroxy‐polybutadienes according to functionality have been effected using stepwise elution from silica gel. Recoveries in the 95–100% range have been achieved. Subjection of the fractions obtained from the silica gel separation to analysis via gel‐permeation chromatography and infrared or near‐infrared spectroscopy yields not only functionality distribution data, but also provides the relationship between molecular weight distribution and functional type. Analytical techniques and interpretation of data are

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090303

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractElectron donors, especially trialkylamines and azulene, have been examined in aluminum alkyl‐, CH3TiCl3‐ and hydrogen‐activated TiCl3catalysts for the polymerization of propylene to isotactic polymer. A comparison and an evaluation were made with findings which were established earlier with zinc alkyl‐based TiCl3catalysts. We find that the donor, when it is present in low concentrations in all of the above catalysts, can inactivate preferentially the less stereoregulating sites. In this way the isotactic content and the molecular weight of the polymer are increased, but only at the expense of a lower catalyst activity. The addition of hydrogen to the TiCl3–donor catalyst at −78°C produced a threefold effect: (1) the activity of the catalyst was increased about 5 to 15 times and higher, (2) the polypropylene formed with this more active catalyst was more isotactic (ca. 10–15%), and (3) the polymer had a lower molecular weight. It is proposed that the increase in catalyst activity was due to the generation of Ti‐H bonds to which propylene molecules then added, the Ti‐H bonds thus being transformed into a

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090304

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe cationic copolymerizations of geometrical isomers of 1,2‐dimethoxy‐ and 1,2‐diethoxyethylenes with vinyl isobutyl ether as a reference monomer have been carried out in methylene chloride at −70° using boron trifluoride etherate as catalyst. The kinetics of the acid‐catalyzed hydrolysis of these ethers has also been investigated in 80% aqueous dioxane, in order to compare the results with the polymerizabilities. It has been found that thecisethers are ca. four times as reactive as theirtransisomers in both reactions. On the other hand, it has been proved that a β‐alkoxyl substitution reduces the hydrolysis reactivity of vinyl alkyl ethers by a factor of ca. 10−3while it even enchances the cationic polymerizability. These contrasting results are interpretable from the nature of the transition states which are different for th

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090305

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractPVC was crosslinked by immersing PVC–dithiol blends in ethylenediamine at 30°C. Properties of the products depended on the chain length and chemical structure of the crosslinkage and on the molecular weight of the polymer chain between crosslinksMc. Crosslinking by the agent of soft structure and long molecular chain resulted in high tensile strength at break and impact strength and low brittle temperature. The use of the crosslinking agent of short molecular chain gave high yield strength, Young's modulus, and heat distortion temperature. The relation ofMcand the chemical structure of the crosslinks to the properties of the crosslinked rigid polymer was discussed in regard to the crosslinking effect and plasticizing effe

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090306

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe benzene solution homopolymerization of vinylferrocene, initiated by azobisisobutyronitrile, gave a series of benzene‐soluble homopolymers. Thus, free‐radical copolymerization studies were performed with styrene, methyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, and isoprene in benzene. With the exception of vinyl acetate and isoprene, which did not give copolymers with vinylferrocene under these conditions, smooth production of copolymers occurred. The relative reactivity ratios,r1andr2, were obtained for vinylferrocene–styrene copolymerizations by using the curve‐fitting method for the differential form of the copolymer equation, by the Fineman‐Ross technique, and by computer fitting of the integrated form of the copolymer equations applied to higher conversion copolymerizations. In styrene (M2) copolymerizations, the curve‐fitting and Fineman‐Ross methods both gaver1= 0.08,r2= 2.50, while the integration method gaver1= 0.097,r2= 2.91. Application of the integration method to methyl acrylate and methyl methacrylate (M2) gave values ofr1= 0.82,r2= 0.63;r1= 0.52,r2= 1.22, respectively. The curve‐fitting method gaver1= 0.15,r2= 0.16 for acrylonitrile (M2) copolymerizations. From styrene copolymerizations, vinylferrocene exhibited values ofQ= 0

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090307

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractPoly(2,6‐diphenyl‐1,4‐phenylene ether) reacts with phenols in the presence of an initiator to form a mixture of low molecular weight hydroxyarylene ethers. Although the reaction is similar to the equilibration of poly(2,6‐dimethyl‐1,4‐phenylene ether) with phenols, higher reaction temperatures and larger initiator concentrations are required. Compounds as 3,3′,5,5′‐tetraphenyl‐4,4′‐diphenoquinone,tert‐butyl perbenzoate, and benzoyl peroxide are active initiators. The structure of the polymer affects the extent to which

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090308

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractCopolymers of 1,3‐butadiene ando‐ andp‐chlorostyrenes have been made by use of alkyllithium initiators. These copolymers have a uniform distribution of the chlorostyrene along the chain, suggesting that the reactivity ratio of 1,3‐butadiene and chlorostyrene is close t

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090309

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

Abstract1,2,4,5‐Tetraaminoanthraquinone and 1,4,5,8‐naphthalene‐tetracarboxylic acid dianhydride react in dimethylacetamide to give a tetrameric prepolymer with balanced endgroups of anhydride and diamine. When this prepolymer is carefully treated with polyphosphoric acid at elevated temperature it is converted to a soluble polypyrrolone type structure with an inherent viscosity of 2.3–2.7. Polymers of this molecular weight can be wet‐spun into pliable fibers from methanesulfonic acid. The TGA curve in air shows little weight loss below 550°C. The polymer can also be solubilized by reduction with sodium dithionite in alkaline aqueous dimethyl

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090310

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY