Crystallization behavior in miscible blends of poly(ε‐caprolactone) and poly(hexylene adipate) with similar thermal properties studied by time‐resolved Fourier transform infrared spectroscopy

Abstract

Melt crystallization behavior in miscible blends of poly(e‐caprolactone) and poly(hexylene adipate) was investigated by Differential Scanning Calorimetry, Polarized Optical Microscopy, Wide Angle X‐Ray Diffraction and time resolved Fourier Transform Infrared Spectroscopy. Both polymers were highly crystalline, had similar thermal properties and exhibited negative birefringence. Fractional crystallization of PCL was observed in blends with <40 wt% PCL. Crystallization kinetics of the polyesters was investigated by monitoring the absorbance intensities of the bands at 841 and 911 cm−1 for PCL and PhAd respectively. Even though PCL exhibited a slow crystallization rate than PhAd at 47°C, simultaneous onsets of crystallization were found in all the blends. In blends with high PCL, the relative crystallinity vales for both the polyesters were found to be coincidental while for blends with low PCL content the induction time of PCL shortened due to PhAd playing the role of nucleation agent. WAXD ruled out co‐crystallization.

Homo- to Co-Polyesters Conversion in the Absence of Reagents Facilitated by Hydrogen Transfer Catalysis

“…In agreement with the frequency analysis of dimers, trimers and tetramers by quantum chemical methods, the bands associated with the C=O stretching vibration of the ester groups in the IR spectrum of the dried samples are not indicative for the analysis of the reaction and showed only a small shift of a comparably broad band from 1720 to 1722 cm -1 . However, previous reports identified bands in the IR spectra, which are unique for crystalline PHA [30,33] and for PCL. [30] Fig.…”

“…[32] However, crystalline PHA gives rise to very similar characteristic reflexes at 21.3° and 23.9°, which are assigned to the 220 and 040 plane. [33,34] In addition to the similar diffraction patterns of PCL and PHA, it has been demonstrated that blends of both polymers do not give rise to new reflexes, [30] indicating the absence of new crystalline domains. By comparison of the diffractograms at ambient temperature and at 110 °C after the catalytic reactions it becomes evident that no additional reflexes of significant intensity are observed for the polymer, which is in line with the formation of polymers with similar diffraction patterns like PHA.…”

“…S2). The Differential scanning calorimetry of blends of polycaprolactone (PCL), for example with polyhexylene adipate (PHA), [30] usually shows an intermediate melting temperature of the blended components, which is an indication for iso(dimorphic) co-crystallisation in these polymers, a case previously studied by some of the authors. [9] In consequence, the changed polymer distribution of PCL after the catalytic reaction is expected to show a reduced melting point in the calorimetric characterisation.…”

Degradation and Mechanical Behavior of Fish Gelatin/Polycaprolactone AC Electrospun Nanofibrous Meshes

“…This can be related to some reduction of PCL crystalline fraction and loss of the preferential orientation of crystalline domains that was induced by the thermal treatment of nanofibers. [68][69][70] The Amide-I and Amide-II peaks show an apparent small shift to higher frequencies, whereas the IR absorption band centered around 3300 cm −1 shows a slight increase in peak intensity with respect to Amide-I and Amide-II peaks. The latter can be related to the retention of both adsorbed and tightly bound water in the FGEL fraction after the SBF-exposed samples were dried.…”

High‐throughput fabrication, structural characterization, and cellular interaction of compositionally diverse fish gelatin/polycaprolactone (PCL) nanofibrous materials

“…This is related to the increase in crystallinity of PCL component. 35,36 Other three peaks (1722, 1470, and 1415 cm À1 ) are due to the vibrational modes perpendicular to the main chain direction. 27,37 The reduction in the intensity of absorption bands associated with the vibrational modes parallel to PCL main chain direction has been observed when the incident infrared light was polarized perpendicular to the fiber axis.…”