摘要:

Samples of starch-g-polyacrylonitrile were prepared using the Ce4+ion as initiator. We discuss the influence of the origin of the starch on the polyacrylonitrile content of the copolymer, on the frequency of the grafted chains, and on the molecular weight of the graft. Relations between alkaline hydrolysis conditions and liquid absorption were also studied. The retention increases with the molecular weight of the grafted polyacrylonitrile, and this factor depends on the origin of the starch. Higher absorptions were obtained with low amylose content samples. An absorption maximum was observed that depends on the time of hydrolysis and consequently on the carboxylate group content.

ISSN:0022-233X    

DOI:10.1080/00222338808051968

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Polyadipic anhydrides were prepared (a) from the mixed anhydride of adipic acid and acetic acid, (b) from the mixed anhydride of adipic acid and ketene in tetrahydrofurane solution (0°C), (c) by melt polycondensation of adipic acid with ketene, and (d) from the seven-membered ring adipic anhydride. The polymers were characterized by means of NMR, IR, DSC, and GPC. The polymer with the highest melting temperature was obtained by melt polycondensation of adipic acid with ketene (Tpeak76°C). The heat of fusion was approximately 40 J/g in all four methods. The number-average and weight-average molecular weights of the polyanhydrides were 2000 and 3000, respectively.

ISSN:0022-233X    

DOI:10.1080/00222338808051969

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Supported chromium oxide catalysts are activated by calcination in dry air at 400–900°C, which dehydrates the carrier and binds chromium(VI) to the surface. A reduction by ethylene then provides the active species. Alternatively, the carrier can be calcined alone and afterward impregnated with an organochromium compound. Both procedures can produce an active catalyst for ethylene polymerization, but the two types differ considerably in their behavior. A third type is made by reacting an organochromium compound with the activated chromium oxide catalyst. This “mixed” catalyst displays some of the characteristics of both parents, but is not a simple combination of the two.

ISSN:0022-233X    

DOI:10.1080/00222338808051970

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

2-(1-Naphthylacetyl)ethyl acrylate (NAEA) was synthesized by esterification of 1-naphthylacetic acid (NAA) and 2-hydroxyethyl acrylate (HEA) and then polymerized to obtain the polymer-bound auxin NAA. The resulting polymer is potentially useful as a plant growth regulator through hydrolytic release of NAA. Copolymers of NAEA with hydrophilic comonomers were prepared by solution polymerization. The copolymer compositions were determined from elemental analysis,13C-NMR, and UV spectroscopy. The copolymer microstructure was predicted from the reactivity ratios in order to investigate the influence on the behavior of controlled release. These model structures will be utilized for assessment of structure/hydrolysis relationships in a subsequent paper.

ISSN:0022-233X    

DOI:10.1080/00222338808051971

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Release properties of the copolymers of 2-(1-naphthylacetyl)ethyl acrylate with hydrophilic comonomers of known molecular weight have been studied as a function of pH, composition, comonomer type, and copolymer microstructure. Fluorescence and solid-state13C-NMR studies have also been performed. Neighboring group effects for the hydrolysis were observed by the concentration of auxin released; the release mechanism differed with the comonomer type. In addition, the release behavior of the ionic copolymers is affected by the presence of intramolecular hydrophobic interactions.

ISSN:0022-233X    

DOI:10.1080/00222338808051972

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Free-radical homo-and copolymerizations of substituted maleimide derivatives in the presence of chiral substances have been reinvestigated. Optically active copolymers were obtained from the copolymerizations of styrene withN-t-butylmaleimide andN-phenylcitraconimide. Optically active homopolymers were obtained fromN-t-butyl-,N-isopropyl-,N-benzyl-, andN-α-phenethylmaleimides, but not fromN-p-tolyl-andN-triphenylmethylmaleimides. The [α] values of poly-N-benzylmaleimide increase both with increasing chiral substance concentration and monomer concentration.

ISSN:0022-233X    

DOI:10.1080/00222338808051973

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Since phospholipids are of considerable interest as essential components of biological membranes [1, 2], it has seemed promising to investigate the behavior of polymeric phospholipid analogs. For over 10 years, a large part of our efforts has been to prepare polymers containing phosphatidylethanolamine [3, 4] or choline [5–7] analogs in the side chains and phosphatidylcholine analogs [8–10] in the main chains. A part of this programs was to synthesize polymeric phospholipid analogs containing nucleosides [11, 12], e.g., uridine, as in the work reported here.

ISSN:0022-233X    

DOI:10.1080/00222338808051974

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:10.1080/00222338808051967

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor