摘要:

The probable minimum-energy structures of three dimeric, three tri-meric, and two hexameric phenol-formaldehyde (PF) condensates were determined by using a simplified model where the total energy was calculated as the sum of the van der Waals, hydrogen bonding, torsional, and electrostatic energies. The minimum-energy conformation was defined as that with internal angles of rotation that correspond to the overall minimum in the total energy. Representations of the structures of these PF condensates in the minimum-energy conformations were obtained. The results obtained indicated that the van der Waals energy, and in some cases the hydrogen bonding energy, make the most important contributions to the total energy. The phenol-formaldehyde dimers and trimers are predicted by this model to have nonplanar structures, and the longer phenol-formaldehyde condensates, such as the hexamers, probably exist in helical conformations.

ISSN:0022-233X    

DOI:10.1080/00222338908052014

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) have been prepared from β,β'-(2-hydroxyl-5-methylbenzoyl)-p-divinylbenzene. The analytical data are found to be consistent with 1:1 metal:ligand stoichiometry. Elemental analyses, magnetic, spectral (IR and electronic), thermal, and electrical properties of the coordination polymers have been studied, and probable structures are assigned to them. All of them are amorphous powders and insoluble in common organic solvents.

ISSN:0022-233X    

DOI:10.1080/00222338908052015

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Radical copolymerizations ofN-(4-substituted phenyl)-α-chloromaleimide (RPhClMI: 1, R = H; 2, R = Cl; 3, R = OCH3; 4, R = CH3; 5, R = COOC2H5) (M1) with styrene (ST) (M2) or methyl methacrylate (MMA) (M2) in tetra-hydrofuran at 60°C were performed with azobisisobutyronitrile as initiator. This report explores the polymerization behavior of RPhClMI and the substituent effects in copolymerizations. The following reactivity ratios were determined:r1= 0.008–0.02,r2= 0.056–0.11 in the RPhClMI-ST system andr1= 0.021-0.11,r2= 0.55–0.63 in the RPhClMI-MMA system. It was found that the relative reactivities (1/r2) of RPhClMI toward a polystyryl radical was not correlated to the resonance-substituent constant (ER), but it was correlated to the polar-substituent constant ([sgrave]) in the modified Hammett equation (log (1/r2) = ρσ + γER). TheMnin the RPhClMI-ST copolymer was 6 000 to 49 000; that of the RPhClMI-MMA copolymer was 2 100 to 9700.

ISSN:0022-233X    

DOI:10.1080/00222338908052016

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Epoxy resins containing quinazolone rings were synthesized and characterized. Epoxy resins were made by reacting bisquinazolone phenol or bisquinazoline with epichlorohydrin or the diglycidyl ether of Bisphenol A. These resins were analyzed by DSC, GPC, IR, and NMR. The electrical and mechanical properties of the cured resins were evaluated. They have glass transition temperature above 200°C and excellent thermal stability, andTgincreases in the order ofo-,m-,p-substituted phenol groups.

ISSN:0022-233X    

DOI:10.1080/00222338908052017

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Poly(p-phenylene-3,4′-oxydiphenylene terephthalamide) (PPOT) and poly(4,4′-oxydiphenylene-4-carbonamidephthalimide-N-yl) (PAI) are compatible. Molecular composites were prepared by solution blending and subsequently solvent casting. The glass transition temperature of the composite increased with increasing fraction of PPOT. Intermolecular interactions between the two components increase due to formation of hydrogen bonds between the amide linkages of the component polymers. The elastic modulus of the composite was always higher than the modulus predicted on the basis of the additivity. Similar deviations from additivity were observed for the bulk density. These desirable results arise from an increase of the packing density of molecules due to the additional hydrogen bonding also shown by the infrared spectra.

ISSN:0022-233X    

DOI:10.1080/00222338908052018

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Based on an improved calculation of activity coefficients, continuous thermodynamics using a generalized divariate Stockmayer distribution is applied to the liquid-liquid equilibrium of random copolymer solutions. The effects of the chemical polydispersity on the cloud-point curve, the shadow curve, the spinodal, and the critical point are discussed. The theory can account for the occurrence of three-phase equilibria as well as for the phase separation in pure copolymers.

ISSN:0022-233X    

DOI:10.1080/00222338908052019

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:10.1080/00222338908052013

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor