Accelerated degradation of highly loaded polypropylene

Abstract

The accelerated aging of six formulations of polypropylene highly loaded with calcium carbonate and containing a surfactant additive (stearic acid) as well as an ultraviolet (UV) stabilizer was studied. Degradation was followed by measuring mechanical properties (elongation percentage and impact resistance), the dynamic mechanical behavior and some chemical changes such as molecular weight and carbonyl group formation along with oxidation temperatures, found by chemiluminescence. The addition of 30 phr of filler to the polymer reduced the stability of the mixture, and the stearic acid used to treat the filler enhanced this effect considerably. On the other hand, the addition of the photostabilizer controlled to some extent such negative effects. though not completely. The most stable formulation was the polypropylene containing only the LJV stabilizer.

Photodegradation of polyethylenes: Comparative effect of Fe and Ca-stearates as pro-oxidant additives

“…For LLDPE-Ca the CL increase was shifted towards lower temperature, and for LDPE-Ca the increase disappears and the formation of peroxide peak, related to concentration of hydroperoxides in samples, was observed at lower temperature. The results obtained are on agreement with the decrease of stability observed by other authors [25,26] using a mixture of CaCO 3 and stearic acid in photo-aged polypropylene. The mechanism of degradation of polymer containing Ca-Stearate is still no clear.…”

The role of filler type in the photo‐oxidation behaviour of micro‐ and nano‐filled polypropylene

“…The degradant effect of nanosized calcium carbonate and, to a lesser extent, of microsized calcium carbonate is not easy to explain, but has been observed also by other researchers 27, 43. Several factors may accounted for this behaviour, such as variations in the morphology, in particular the formation of defects at the interface between matrix and filler an also at the interface between crystal and amorphous regions.…”

“…The behaviour of polyolefin/mineral (inorganic) composites (calcium carbonate, talc, etc.) has also been studied and variable trends were found 26–29. There are reports that one of the main shortcomings of polymer/silicate (both natural and organo‐modified) nanocomposites is that they suffer from higher photo‐oxidation rates (and, thus, have poorer mechanical properties such as tensile strength and elongation at break) than pristine matrices.…”

Effects of UV weathering on the mechanical and antibacterial performance of peroxide‐cured silicone rubber containing biocide HPQM

“…Gorur et al studied the effects of outdoor aging on physical and chemical changes in silicone rubber and observed some permanent changes, including a depletion of low‐molecular‐weight polymer on the surface, depolymerization, surface roughness, and increased surface crystallization. The damaging and degradation mechanisms resulting in deteriorations of the mechanical properties of silicone rubber via proton radiation were suggested by Zhang et al , Belhaneche‐Bensemra , and Benavides et al .…”