Photo-oxidation behaviour of polyethylene/multi-walled carbon nanotube composite films

Improvement of photo-stability of LLDPE-based nanocomposites

LLDPE-based nanocomposites undergo faster photo-oxidation than the unfilled matrix and the extent of their physical properties deterioration, namely elongation at break and tensile strength, is dependent on the organo-nanoclay loading. The observed acceleration is not due to faster photo-oxidation but rather due to a reduction of the oxidation induction time. The presence in the organoclays of trace amounts of metal ions may be promoting catalytic photodegradation. While UV absorbers provide useful protection, use of a metal deactivator has been found to greatly enhance the photo-stability of the LLDPE-based nanocomposites. Combinations of a metal deactivator and UV absorber yield synergist…

Photo-oxidation behaviour of composite polyethylene/MW-CNTs

Photo-oxidation behaviour of composite polyethylene/MW-CNTs films

Polyolefin based nanocomposites: a method to achieve better dispersion of nanoclays in PE films and improve their physical properties

UV-stabilisation of polystyrene-based nanocomposites provided by polyhedral oligomeric silsesquioxanes (POSS)

Abstract The photo-ageing behaviour of Polyhedral Oligomeric SilSequioxane (POSS)-polystyrene (PS) nanocomposites has been investigated for the first time. POSS having different inorganic framework and pendant organic groups have been used in the PS nanocomposite preparation and the formulated films were subjected to accelerated weathering. Compared to pristine PS, the POSS-containing PS developed a lower level of carbonyl and hydroxyl groups as a function of the exposure time, indicating a significantly improved resistance of the nanocomposites to photo-degradation. The results suggest that all of the investigated POSS molecules play a protective role and may extend the in-use lifetime of …

Photooxidation and photostabilization of EVA and cross-linked EVA

Abstract Cross-linked EVA copolymers are widely used as encapsulant material for photovoltaic modules in order to protect the solar cell from the dangerous and degrading environmental factors like moisture and UV radiations. The protection of these modules from photooxidation is the main important objective in their production. In this work, samples of cured EVA in presence of different types of stabilizers have been photooxidized to better understand the photooxidation behavior and the effects of these stabilizers on the mechanical properties. All the results obtained on the cross-linked samples have been compared with those obtained in the same conditions and with the same formulations wi…

The role of different dispersing additives in the photo-oxidation behaviour of polyolefin-based OMMT nanocomposites

Photochemical stabilization of LLDPE/clay nanocomposites: towards durable nanocomposites

This article reports a study of the chemical modifications of LLDPE/nanoblend nanocomposites exposed to UV light in conditions of artificially accelerated ageing and natural weathering. Analysis by infrared spectroscopy of the chemical modifications produced by photoageing shows that the presence of an organo-clay leads to the decrease of the oxidation induction time of the polymer (LLDPE), which results in lower durability of the nanocomposites. Protection against photooxidation was tested with different kinds of UV stabilizers and with a metal deactivator. It is shown that the metal deactivator is very efficient in stabilizing the nanocomposite since it totally cancels the prodegradant ef…

Photo-oxidation behaviour of polyethylene/multi-wall carbon nanotube composite films

Abstract The resistance to accelerated photo-oxidation of polyethylene/multi-walled carbon nanotubes (MW-CNTs) composite films was compared with the photo-oxidation behaviour of pristine polyethylene film. The polyethylene/MW-CNTs films containing different CNTs loading were subjected to accelerated UV-B exposure. At short exposure time, i.e. under 200 h, the rates of carbonyl formation are very similar to that observed for pristine polyethylene film but at longer irradiation times the carbonyl formation increases for lower MW-CNTs contents (0.1, 0.2 and 0.5% wt./wt.), and decreases for higher MW-CNTs contents (1 and 2% wt./wt.). By adding a UV-stabilizer to the films their photo-oxidation …

Effect of different dispersing additives on the morphology and the properties of polyethylene-based nanocomposite films

In this work, the use of a polar wax, e.g. amphiphilic Tegomer ® E 525 (TEG) is investigated with the aim of mod- ifying, and possibly improving, the dispersion of an organically modified nanoclay (OMMT), loaded at 5 wt%, in a poly- ethylene matrix (PE) at relatively low loading levels. We have indeed found that the incorporation of low loadings, e.g. 0.5 wt%, of TEG, an amphiphilic block co-polymer, into a PE/OMMT sample results in a substantial improvement of the clay dispersion in the nanocomposite and, consequently, of the mechanical and thermomechanical properties of the films. The achieved results are comparable to those obtained for systems containing traditional dispersing agents su…