MORPHOLOGY AND PROPERTIES OF TRANS-1,4-POLYISOPRENE CRYSTALLIZED FROM SOLUTION.
Item
-
Title
-
MORPHOLOGY AND PROPERTIES OF TRANS-1,4-POLYISOPRENE CRYSTALLIZED FROM SOLUTION.
-
Identifier
-
AAI8423080
-
identifier
-
8423080
-
Creator
-
KUO, CHEN-CHIH.
-
Contributor
-
A. E. Woodward
-
Date
-
1984
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Chemistry, Polymer
-
Abstract
-
Trans 1,4 polyisoprene (TPI) fractions with average number molecular weight ((')M(,n)) from 4.7 x 10('3) to 2.5 x 10('5) and molecular weight distribution ((')M(,w)/(')M(,n)) of 2.0 to 1.3 were crystallized from solutions, mainly at a concentration of 1g per 100 cm('3), by cooling directly from 100(DEGREES)C to an apparent crystallization temperature (T(,C)) of -15 to +32(DEGREES)C, by precooling to 0(DEGREES)C, redissolving at 35-45(DEGREES)C and crystallizing at T(,C), and by cooling to 0(DEGREES)C and heating to 10(DEGREES), 20(DEGREES), or 30(DEGREES)C. Most of the structures obtained were characterized, while suspended in the crystallization liquid, by interference contrast microscopy and with crossed polaroids; the crystalline fraction from the density, and the crystal form, from x-ray diffraction and differential scanning calorimetry, were determined for the dry products. The morphology obtained by direct crystallization was dependent on molecular weight, crystallization temperature and solvent with (alpha)- and (beta)-hedrites, (alpha)- and (beta)-spherulites and (beta)-aggregates of cup-shaped lamellas being found. The precooling method yielded overgrown lamellas in most cases, however more complex morphologies developed when the thermal history was changed. The density depended on molecular weight, concentration and crystallization temperature. The crystallinity was mainly a function of crystal form and molecular weight. The equation of Tseng, Herman, Woodward and Newman was used to explain the molecular weight dependence of the crystallinity at low (')M(,n) and to calculate the average number of monomer units per fold and interlamellar traverse. Epoxidation of some TPI structures suspended in amyl acetate at 0(DEGREES)C was carried out. At high concentrations of the epoxidizing agent, metachloroperbenzoic acid, the fraction epoxidized approached or exceeded the non-crystalline fraction was obtained from density measurement.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
-
Program
-
Chemistry
