摘要:

3,4/cis-1,4-Polyisoprenes were prepared with Fe(acac)3-Al(i-Bu)3catalyst. These polymers are of interest because of their higher 3,4 content and different degree of crystallinity. The13C-NMR spectra of these polymers were much more complex than those previously reported and were assigned using slightly modified empirical parameters based on Gronski et al. In order to further clarify the assignments, hydrogenation of the polymers was carried out, and the13C-NMR spectra of the hydrogenated polymers were partially assigned. Based on these assignments, it was found that the existence of long sequences of vinyl monomer units might be a favorable factor for the formation of partially crystallized polymer. Finally, the13C-spin relaxation timesT1, as well as their temperature dependence, were also measured in chloroform-d1solvent at 50 MHz, and the Arrhenius activation energy was estimated.

ISSN:0022-233X    

DOI:10.1080/00222338808051958

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Polymerization exotherms of 1,6-hexanediol diacrylate (HDDA) were generated by a pulsed laser source and recorded on a modified differential scanning calorimeter. Several aromatic carbonyl-based photoinitiators were compared with respect to maximum rate and extent of polymerization in the absence and presence of oxygen. α-Cleavage photoinitiators were more efficient than the hydrogen-abstracting benzophenone. The addition of an amine to a photocleavable initiator improved the polymerization of HDDA under an inert atmosphere, whereas triarylphosphines under similar conditions were effective in reducing the air inhibition. This synergistic effect depends on the type and structure of the additive and the photoinitiator.

ISSN:0022-233X    

DOI:10.1080/00222338808051959

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abinitioself-consistent field molecular orbital calculations have been performed to obtain the intramolecular rotational potential energy surface forcis-transoidalpolyacetylene with simultaneous rotations about two successive single bonds. The results indicate the possibility of existence of a “superhelix” instead of a tight 2*3/1 helix. Using the energy surface obtained, Monte Carlo calculations have been done to obtain the probabilities of the existence of various conformations of this polymer.

ISSN:0022-233X    

DOI:10.1080/00222338808051960

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The effects of solvent and temperature on the grafting of poly(N-vinylcarbazole) (NVC) onto carbon fiber by cationic polymerization initiated by carboxyl groups on the surface were investigated in order to obtain poly-NVC-grafted carbon fiber with a higher percentage of grafting It was found that the rate of the polymerization of NVC increased, depending on the dielectric constant of the solvent, in the following order: toluene < 1,2-dichloroethane < nitrobenzene. However, the percentage of grafting of poly-NVC onto the carbon fiber obtained from polymerization in nitrobenzene was smaller than that in toluene. This may be due to differences in the chain transfer of the growing polymer cation to NVC and these solvents. Furthermore, poly-NVC-grafted carbon fiber with a higher percentage of grafting was formed at a lower polymerization temperature, i.e., 60°C. In addition, it became apparent that carbon fiber is capable of initiating the cationic polymerization ofN-vinyl-2-pyrrolidone (NVPD), and poly-NVPD was grafted onto carbon fiber, depending on the termination reaction of the growing polymer cation with carboxylate anion on carbon fiber. However, cationic polymerization of isobutyl vinyl ether and α-methylstyrene was scarcely initiated by carbon fiber.

ISSN:0022-233X    

DOI:10.1080/00222338808051961

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

For special applications of composite materials, particularly for biomedical uses, the interface between polymer and solid should have a less ordered molecular architecture in order to confer the mobility needed for reactions of ions and low molecular weight agents. Therefore, composites were obtained by controlled reaction of macromolecules, mainly polyepoxides derived from polybutadiene, with glass ceramics which are biocompatible and bioactive. Direct linking of the reacting components by covalent bonds has been demonstrated by IR and NMR spectroscopy using model reactions with silica and other oxides.

ISSN:0022-233X    

DOI:10.1080/00222338808051962

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The photochromic behavior of viologens (V2+) and polyviologens (PV2+) was investigated using poly(N-vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) as matrices. In the PVP matrix the coloration rate of butylviologen bromide increases with decreasing humidity, but no influence of humidity on coloration rate was observed in the PVA matrix. The coloration rate in the PVA matrix follows a second-order plot while in the PVP matrix it does not. These results imply that, for the coloration process of viologens in polymer matrices, the effect of the matrix polymer as an electron donor must be considered. The fading rate of colored poly(butylviologen bromide) in PVP matrix increases remarkably with humidity. The fading reaction obeys a first-order relation at the very beginning and permits the determination of the rate constant. The fading rate increases with temperature with an activation energy of 13 kcal/mol. The fatigue of viologens and polyviologens was evaluated by the half-decay flash number. Polyviologens are more durable than their lower homologs.

ISSN:0022-233X    

DOI:10.1080/00222338808051963

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Copolymers like 8-hydroxyquinoline-furfural, 2,4-dihydroxyacetophenone-furfural, β-resorcylic acid-furfural, anthranilic acid-furfural, and salicylic acid-furfural are well-known polymeric ligands [1–4], and their ion-exchange properties have been reported. In the present paper, we report the preparation and characterization of β-resorcylaldehyde-furfural (RAF) polymer and its polychelates with the bivalent metal ions CU2+, Ni2+, Co2+, Mn2+, and Zn2+.

ISSN:0022-233X    

DOI:10.1080/00222338808051964

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Anionic polymerization of acrylonitrile was achieved by constant-potential electrolysis via direct electron transfer to the monomer. The reduction peak potential in the (C4H9)4NBF4-CH3CN electrolyte-solvent system was measured by cyclic voltammetry. On the other hand, dimethylformamide-metal salts were not found suitable for the direct electron-transfer process in our system. Polymers produced both anodically and cathodically were found to contain cyclized structures.

ISSN:0022-233X    

DOI:10.1080/00222338808051965

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

There are no previous descriptions of the preparation or properties of oligomeric products from the acid-catalyzed reaction of equimolar proportions of carbonothioic dihydrazide and dialdehydes. Di(alkylidene)carbonothioic dihydrazides are known as the products of the reaction of 1 or 2 mol monofunctional aldehydes [1–3] with 1 mol carbonothioic dihydrazide. The products of the reaction of 1 mol glyoxal bisulfite [4, 5] or kethoxal [5, 6] with 1 or 2 mol carbonothioic dihydrazide have been reported These products are soluble and do not have the properties of the oligomers described here.

ISSN:0022-233X    

DOI:10.1080/00222338808051966

出版商:Taylor & Francis Group    

年代:1988

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:10.1080/00222338808051957

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor