UV degradation of clay‐reinforced polypropylene nanocomposites

Abstract

The aim of this work is to experimentally characterize the UV‐degradation process at both the surface and at different layers across the thickness of injection‐molded polypropylene (PP) matrix containing different amounts of nanosized montmorillonite (MMT) clay particles. These nanocomposite materials have been exposed to UV irradiations (λ = 320 nm) at different preset temperatures (25, 45, and 65°C) in the presence of oxygen and during different exposure times. The extent of such process at these layers was determined using both the FTIR spectroscopy and the wide‐angle X‐ray diffraction analyses. The micromechanical properties across the thickness have been characterized using the nanoindentation technique. The obtained results have indicated that the UV‐degradation process for the nanocomposite materials is much more intense than the one observed for the neat PP. Moreover, it has been noted that such degradation process is not uniform across the thickness of the exposed materials. Results obtained from the X‐ray analysis have shown an increase of the crystallinity of the polymer molecules at only the external surface of the exposed materials. This was confirmed using the nanoindentation test as an increase of the Young's modulus at this layer was noted. POLYM. ENG. SCI., 56:469–478, 2016. © 2016 Society of Plastics Engineers

Environmental effects of ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2017

“…Because of their high surface area per unit mass, nanoscale UV-absorbing fillers are particularly efficient UV stabilisers in some plastics. 466,467 For instance, incorporating 1% (w/w) nanoclay 468,469 or rutile titanium dioxide (TiO 2 ) 470 in poly(lactic acid) plastics or 2% (w/w) TiO 2 in acrylic films 471 resulted in marked improvement in their UV stability in terms of loss of tensile properties 467,469,470 or as weight loss. 471 However, mixing 2% (w/w) of nanoclay in polystyrene 472 or 5-8% TiO 2 nanotubes in PP 473 unexpectedly accelerated their photodegradation.…”