Next Article in Journal
Development and Characterization of Sustainable Composites from Bacterial Polyester Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate) and Almond Shell Flour by Reactive Extrusion with Oligomers of Lactic Acid
Next Article in Special Issue
Effect of Different Phosphate Glass Compositions on the Process-Induced Macromolecular Dynamics of Polyamide 66
Previous Article in Journal
A Review on Barrier Properties of Poly(Lactic Acid)/Clay Nanocomposites
Previous Article in Special Issue
Optimization of Serial Modular Continuous Mixing Process Parameters for Natural Rubber Composites Reinforced by Silica/Carbon Black
Open AccessArticle

Effects of Rutile–TiO2 Nanoparticles on Accelerated Weathering Degradation of Poly(Lactic Acid)

Center for Advanced Materials, Qatar University, P.O. Box 2713 Doha, Qatar
*
Author to whom correspondence should be addressed.
Polymers 2020, 12(5), 1096; https://doi.org/10.3390/polym12051096 (registering DOI)
Received: 12 April 2020 / Revised: 4 May 2020 / Accepted: 8 May 2020 / Published: 11 May 2020
(This article belongs to the Special Issue Polymer Nanocomposites: Processing, Degradation and Applications)
The effect of accelerated weathering on poly(lactic acid) (PLA) and a PLA nanocomposite with rutile titanium (IV) dioxide (rutile–TiO2) was investigated. The accelerated weathering test applied consecutive steps of ultraviolet (UV) (at 340 nm and 0.76 W m−2 irradiance) and moisture at 50 °C for 2000 h, following the ASTM D4329 standard. The morphology, chemical structure, molecular weight, crystallization, as well as mechanical and thermal properties were thoroughly studied. Samples were characterized after 500 h, 1000 h and 2000 h exposure. Different degradation mechanisms were proposed to happen during the weathering exposure and confirmed based on the experimental data. The PLA and PLA/TiO2 surfaces presented holes and increasing roughness over the exposure time. The molecular weight of the weathered samples decreased due to chain scission during the degradation processes. Thermal stability decreased in the presence of TiO2 and a double melting peak was observed for the PLA/TiO2 nanocomposite. A general improvement in the mechanical properties of the PLA/TiO2 nanocomposite was observed over time during the accelerated weathering analysis up to 1000 h of exposure time. After 2000 h of weathering exposure, the PLA and PLA/TiO2 became extremely brittle and lost their ductile properties. This was ascribed to a significant increase in the degree of crystallinity upon weathering, which was accelerated in the presence of TiO2. Atomic force microscopy (AFM) using amplitude modulation–frequency modulation (AM–FM) tool confirmed the mechanical changes in the surface area of the PLA samples after accelerated weathering exposure. The stiffness and Young’s modulus achieved higher values than the unweathered ones up to 1000 h of exposure time. The changes in the physical and chemical properties of PLA/TiO2 over the ageing time confirm the photocatalytic activity of rutile–TiO2. View Full-Text
Keywords: poly(lactic acid); rutile titanium (IV) dioxide; accelerated weathering degradation; morphology and properties poly(lactic acid); rutile titanium (IV) dioxide; accelerated weathering degradation; morphology and properties
Show Figures

Graphical abstract

MDPI and ACS Style

Antunes, A.; Popelka, A.; Aljarod, O.; Hassan, M.K.; Luyt, A.S. Effects of Rutile–TiO2 Nanoparticles on Accelerated Weathering Degradation of Poly(Lactic Acid). Polymers 2020, 12, 1096.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop