Photochemically cross-linked poly(epsilon-caprolactone) with accelerated hydrolytic degradation

Irradiation of benzophenone (BP)-doped poly(epsilon-caprolactone) (PCL) films at lambda > 350 nm alters the molecular characteristics, viscoelastic properties and hydrolytic degradation rate. The influence of BP concentration on changes caused by irradiation of BP-doped PCL film was investigated using gel permeation chromatography along with analyses of gel content, DSC and rheology. Changes in the rate of basic hydrolysis of irradiated BP-doped PCL films were also investigated. Irradiation of PCL film doped with at least 0.5% w/w BP led to cross-linking and gel formation, even though simultaneous degradation was also observed. Polar groups formed during the irradiation of BP-doped PCL films enhanced the hydrolysis of cross-linked PCL films compared with untreated films. (C) 2015 Elsevier Ltd. All rights reserved.Slovak Research and Development Agency [APVV-0109-10]; Grant Agency VEGA [2/0112/13]; Centre of Excellence SAS for Functionalized Multiphase Materials (FUN-MAT); Operational Program Research and Development for Innovations; European Regional Development Fund (ERDF); Centre of Polymer Systems project, Czech Republic [CZ.1.05/2.1.00/03.0111

UV initiated oxidation and chemiluminescence from aromatic-aliphatic co-polyesters and polylactic acid

The chemiluminescence of UV irradiated aromatic-aliphatic polyesters (Ecoflex and PBAT) and polylactic acid (PLA) was examined in nitrogen and oxygen atmospheres during the non-isothermal temperature runs in the interval from 40 to 250 C and isothermally from 150 to 190 C. The non-isothermal thermogravimetry and FTIR spectroscopy have been used for the characterization of differences in original samples. The temperature maxima of peroxidic peaks in nitrogen scaling their stability were compared and found to be in the order PBAT < Ecoflex < PLA. Their positions on the temperature scale that correlate well with the melting temperature of the respective polymer have been discussed. With prolongation of the UV irradiation period, the intensity of peroxidic peaks increased. On the other hand, the effect of pre-irradiation on non-isothermal runs of chemiluminescence measured in oxygen was not as distinct as for measurements in nitrogen. The deconvolution of the non-isothermal chemiluminescence runs in nitrogen revealed two kinds of peroxides in irradiated samples. © 2013 Elsevier Ltd. All rights reserved