Crystallization study on absorbable poly(p‐dioxanone) polymers by differential scanning calorimetry

Abstract

An investigation was carried out on the crystallization behavior of pdioxanone polymers using differential scanning calorimetry (DSC). Kinetic analyses were performed on data collected primarily during isothermal crystallization. Isothermal data were treated within the framework of the classical Avrami equation. Using this approach, both the Avrami exponent, n, and the crystallization half-time, t 1/ 2 , were evaluated and their implications are discussed for each system studied. It is shown that a small change in the polymer's composition greatly affects the crystallization kinetics, as well as the crystallizability of the materials. Additionally, nonisothermal crystallization under controlled heating and cooling rates was explored. In the case of cooling from the melt, the Ozawa theory and the recently proposed Calculus method were employed to describe the nonisothermal crystallization kinetics. In view of our results, the validity of these two estimation techniques for determining important kinetic and morphological parameters is also discussed.

Study of reorientational dynamics during real-time crystallization of absorbable poly(p-dioxanone) by dielectric relaxation spectroscopy

“…Further experimental consideration of our DSC facility has been described in detail elsewhere. 6 During DRS and DSC measurements, isothermal runs were made in randomized order to avoid any bias due to possible molecular weight degradation. All temperature runs for a given polymer were performed on a single sample, and the selfconsistency of the data engenders confidence that molecular weight loss during testing is not a matter of concern.…”

“…6,7 This feature makes PDS a suitable polymer for the study of dipolar relaxations in the presence of crystallinity because dielectric measurements can provide real-time monitoring of the crystallization process. Likewise, the rationale of using DRS for kinetic purposes is its ability to examine a wide range of crystallization rates in a variety of materials, including some biologically important groups of slow-crystallizable polymers and copolymers.…”

“…7 In Figure 9, the maximum radius of the spherulite is plotted against crystallization temperatures for …”

“…As a first step toward reaching these goals, we recently conducted comprehensive studies on crystal morphology, nucleation, and spherulitic growth rates of poly(p-dioxanone) (PDS) homopolymer and an 89/11 PDS/glycolide segmented block copolymer with differential scanning calorimetry (DSC) 6 and hot-stage optical microscopy (HSOM). 7 An unusually wide range of crystallization conditions was experimentally accessible, allowing the inspection of various morphological features and accurate estimations of characteristic growth parameters, including radial growth and nucleation rates.…”

“…7 An unusually wide range of crystallization conditions was experimentally accessible, allowing the inspection of various morphological features and accurate estimations of characteristic growth parameters, including radial growth and nucleation rates. Crystallization kinetics determined by bulk calorimetric measurements appear to be consistent with the morphological observations (via HSOM).…”