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Polymerization of bicyclic ethers
No full textStructure of copolymers obtained by ring opening cationic polymerization from 7-oxabicyclo[ 2.2.1] heptane and ethylene oxide has been recently reported. This study about the spin lattice relaxation times and Nuclear Overhauser enhancement factor in the carbon-13 NMR spectra was performed and the results interpreted in terms of different internal mobility of the units in the copolymer chain
PREPARATION AND CHARACTERIZATION OF COMB-SHAPED POLYESTERS FROM 2,2-DIOCTADECYL-1,3-PROPANEDIOL AND PHTHALIC ACIDS
No full textNew types of comb-shaped polyesters have been prepared by transesterification of 2,2-dioctadecyl-1,3-propanediol and the three isomeric diphenyl phthalates. Intrinsic viscosity and SEC analyses allowed determination of DPs (60-89) and molar masses; results compare well with absolute average weight molar masses (56,000-118,000) determined by low-angle laser light scattering. High-resolution C-13 NMR reveals the characteristic aromatic and glycol polyester patterns; it resolves many side-chain methylene carbons, but shows no evidence of end-groups. All the polyesters are crystalline as shown by X-ray diffractometry and DSC, the crystallinity being exclusively due to the octadecyl side-group crystallization in the hexagonal form. The results indicate that the crystallinity decreases substantially when going from the ortho- to the terephthalate polyester
Synthesis and characterization of comb-shaped polyesters based on 2-octadecyl-1,3-propanediol and phthalic acids
No full textThree isomeric poly(2-octadecyl-1,3-trimethylene phthalate)s were prepared by melt transesterification of the corresponding diphenyl ester and 2-octadecyl-1,3-propanediol. Intrinsic viscosity, size exclusion chromatography and light scattering determinations yielded weight-average molecular masses of 110 000 and higher. High-resolution, solution C-13 n.m.r. spectroscopy analysis of both the diphenyl ester precursors and polyesters identified the main-chain units, the isomeric aromatic acid residue and glycol carbons, the linking and the terminal ends of the octadecyl side chain, and finally allowed detection of phenyl ester end groups at 1-2% level. No absorption band due to hydroxyl end groups was monitored in the i.r. polyester spectra. I.r. spectroscopy, d.s.c. and powder X-ray diffractometry provided a clear indication of the crystallinity of the prepared polyesters. The relevant melting enthalpy values and X-ray diffraction patterns were typical of comb-shaped polymers in which the paraffinic side chains crystallize independently with their characteristic hexagonal packing
Polymerization of bicyclic ethers: 2. N.m.r. structure study of the polymer formed from 3-oxabicyclo[3,2,2]nonane
No full textPOLYETHER POLYESTER BLOCK COPOLYMERS BY NON-CATALYZED POLYMERIZATION OF EPSILON-CAPROLACTONE WITH POLY(ETHYLENE GLYCOL)
No full textSYNTHESIS AND CHARACTERIZATION OF POLYMERS FROM BETA-PROPIOLACTONE AND POLY(ETHYLENE GLYCOL)S
No full textStudio calorimetrico del polimorfismo di un nuovo poliestere contenente gruppi laterali cianoazobenzenici
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