Influence of previous annealing on first stage of degradation of blends of low‐density polyethylene and Mater‐Bi AF05H aged in soil: Comparative thermal analysis study

Abstract

AbstractSamples of low‐density polyethylene (LDPE) filled with a commercial biodegradable material (Mater‐Bi AF05H) were subjected to an accelerated soil burial test in a culture oven. In addition, another series of these blends was subjected to thermal treatment and afterward buried in soil under the same conditions. Comparative studies of the changes in the thermal stability and the structural and morphological properties of the samples were carried out by means of differential scanning calorimetry, dynamic mechanical thermal analysis, and thermogravimetric analysis. The morphological properties under study were the melting temperature, the crystalline content, and the lamellar thickness distribution. The αI relaxation zone of the mechanical spectra was characterized in terms of tan δ, whereas the αII and relaxation zones were characterized in terms of E″ according to the Fuoss–Kirkwood equation and with the help of a deconvolution method. Finally, the kinetics of each thermodegradation process was studied using the Broido integral method. The Mater‐Bi hindered the uniform growth of crystallites in PE and facilitate molecular motions, but the thermal treatment seemed to rearrange the crystallites in the crystalline phase of PE and promote segregation of the crystallite sizes. These molecular reorganizations affected the degradation process so that the degradation of the polymeric matrix seemed to be obstructed by the annealing during the first 120 days of aging in soil and only the Mater‐Bi degradation could be observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3359–3373, 2003