Effect of iron carboxylates on the photodegradability of polypropylene. I. Natural weathering studies

Abstract

AbstractTo enhance the photodegradability of polypropylene (PP), various carboxylates of iron, including ferric caprate (MF03), ferric laurate (MF04), ferric myristate (MF05), ferric palmitate (MF06), and ferric stearate (MF07), were synthesized. Virgin PP was blended with the synthesized prodegradants (0.2%) and blown into films. To study the photodegradation behavior of PP with and without the prodegradants under natural weathering conditions, all of the films were exposed to sunlight according to the procedure of ASTM 1435. All of the weathered films were found to degrade after a certain number of days of exposure; this was found from the steep increases in the carbonyl, hydroperoxide, hydroxyl, lactone, ester, carboxylic acid, and crystallinity indices. At the same time, a sudden decrease in the elongation at break percentages and tensile strength and surface cracks were also observed. PP containing the prodegradants degraded at a faster rate than the virgin material. The time taken for the material to lose half of the elongation at break value was taken as the half‐time, and this was used to determine the effectiveness of the prodegradants. The effectiveness of the prodegradants for the photodegradation of PP was found to be in the following order: MF03 > MF04 > MF05 > MF06 > MF07. With increasing alkyl chain length of the prodegradants, the stability of the alkyl radical increased, whereas the mobility of the radical in the PP matrix decreased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010