ISSN:
1022-1352
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
A series of hydroxypropyl cellulose (HPC) derivatives with, on the average, 3, 2, 3/2, 1, 1/2, 1/3 alkyl side chains (18 carbons) on each anhydroglucose unit were synthesized. X-ray studies indicate that layered structures prevail in most of these HPC derivatives, even in the sample containing only one alkyl side chain per two rings, i.e. C18(1/6)HPC. The polymers were able to pack in better ordered arrays in the solvent-cast films than in as-made samples obtained by precipitation from a nonsolvent. Side chain melting endotherms were observed for C18(3/3), C18(2/3), C18(1/6), and C18(1/9)HPC's. In C18(1/2) and C18(1/3)HPC's, side chain melting enthalpies were negligible but isotropization enthalpies were unexpectedly large. The isotropization temperatures and the associated enthalpies remained almost constant in differential scanning calorimetry (DSC) heating/cooling cycles. Distinct morphological features were observed under the cross polarized optical microscope (POM) after shearing the samples in the molten state. The degree of side chain substitution has a profound influence on the polymer morphology.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
Permalink
