摘要:

Continuous thermodynamics was developed in recent years and applied successfully to the liquid-liquid equilibrium of poly disperse polymer solutions. Continuous thermodynamics is based on the direct use of continuous distribution functions in the thermodynamic equations. There is no need for a reduction to pseudocomponents. This paper presents the application of continuous thermodynamics to successive polymer fractionation procedures based on solubility differences. In this way, simple equations for the distribution function of the different polymer fractions are obtained. Furthermore, the other equations describing the fractionation possess a lucid structure favorable for computer simulations of the fractionation procedures.

ISSN:0022-233X    

DOI:10.1080/00222338908052021

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A series of phosphorus-containing nadimide-endcapped resins was prepared by reactingendo-5-norbornene-2,3-dicarboxylic acid anhydride (nadic anhydride), 3,3′,4,4′-benzophenonetetracarboxylic acid dian-hydride, and tris(3-aminophenyl)phosphine oxide in glacial acetic acid/ dimethylformamide. Structural characterization of resins was done by elemental analysis, FTIR, and1H NMR. In DSC traces of these resins, an exothermic transition associated with crosslinking was observed above 280°C. Thermogravimetrie studies revealed a multistep decomposition reaction. Residual weight at 800°C in nitrogen was found to depend on the backbone structure and ranged from 42 to 60%.

ISSN:0022-233X    

DOI:10.1080/00222338908052022

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

ß-D,L,-Butyrolactone was polymerized at 50°C in deuterated solvents of different polarity, and both the conversion and the formation of crotonate groups were directly determined from the reaction mixture by means of1H-NMR spectroscopy. Two classes of initiators, namely nonionic ones, such as tertiary amines or triphenylphosphine, and ionic ones, such as potassium salts of alcohols, phenols, and carboxylic acids, were used. In almost all polymerizations, formation of crotonate end groups was detected. Two deprotonation mechanisms are discussed. This side reaction is the main reason why high molecular weight poly(ß-C,L-butyro-lactone) could not be obtained even when the monomer/initiator ratio was varied by a factor of 40. In contrast, the nonionic initiator tributyltin methoxide yielded poly(ß-D,L-butyrolactone) free of crotonate groups. When potassium salts ofN-protectedL-amino acids were used as initiators, again crotonate end groups were formed even at +5°C, and the resulting poly(ß-D,L-butyrolactone) was almost atactic.

ISSN:0022-233X    

DOI:10.1080/00222338908052023

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Thermostable heterocyclic polymers containing phenyl-substituted quinoxaline and both amide and imide units have been synthesized by low-temperature solution polycondensation of diaminophenyl-quinoxalines with diacid chlorides of certain aromatic acids containing preformed imide rings. Also, copolymers have been obtained in which a mixture of diaminophenylquinoxaline and diaminooxadi-azole or diaminobenzimidazole was used in the reaction with the same diacid chlorides. The thermal stability and the electrical insulating properties of these products are discussed and compared with related heterocyclic polymers.

ISSN:0022-233X    

DOI:10.1080/00222338908052024

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

It is well known that maleic anhydride (MAH) behaves as an electron acceptor and forms charge-transfer complexes with donor monomers such as styrene (ST) [1,2], divinyl ether [3], and some of other olefms [4–61. The charge-transfer polymerization of ST with MAH has been extensively studied [1,7–11]. On the other hand, L-ascorbic acid (L-Asc) in combination with a suitable oxidants proved to be an efficient redox initiator for various vinyl polymerizations. Misra et al. [12] showed that the reduction of peroxides by ascorbic acid follows a chain mechanism with ascorbate and other free radicals as intermediates. Thus, we can expect that such an electron donor might initiate the copolymerization of MAH with ST.

ISSN:0022-233X    

DOI:10.1080/00222338908052025

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Esters are usually prepared by the acid-catalyzed reaction of alcohols and phenols with acids or acid derivatives, such as acid chlorides and anhydrides. In the presence of the reaction products, the esterification step is followed by the similar acid-catalyzed homogeneous hydrolysis of the polymer. Both the formation of the polymer and the hydrolysis reaction that follows are accompanied by considerable degradation of the polymer chain leading to deterioration of the polymer end-use properties.

ISSN:0022-233X    

DOI:10.1080/00222338908052026

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Poly(amide-hydrazide)s were originally developed to give fibers of high modulus and high strength [1]. They were generally prepared 1) from dicarboxylic acid chlorides and aminohydrazides by low-temperature polycondensation [2,3]; 2) by the phosphorylation method [4, 5]; and 3) from dihydrazides with preformed amide linkages by low-temperature polycondensation [6]. These polymers were found to be thermally stable, but they showed poor solubility in polar aprotic solvents. In this paper we report the synthesis and characterization of some new poly(amide-hydrazide)s with azo groups in the backbone, which were introduced to improve solubility.

ISSN:0022-233X    

DOI:10.1080/00222338908052027

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222338908052020

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor