Search results for " polycarbonate"

Theoretical study on the decomposition mechanism of bisphenol A polycarbonate induced by the combined effect of humidity and UV irradiation.

2020

Polycarbonate (PC) is a good material for covering and protecting cultural heritage sites because of its durability, mechanical properties, and transparency. When bisphenol A polycarbonate is subjected to weathering conditions this polymer shows several degradation processes depending on the irradiation wavelength, humidity and temperature. In particular, the combined effects of humidity and UV irradiation speed up the PC molecular weight reduction. In this work, the decomposition mechanisms associated to the hydrolysis process are scrutinized and the effects of UV irradiation on the hydrolysis process are evaluated throughout the Density Functional Theory (DFT) approach. It was found that …

Thermomechanical properties and thermal degradation kinetics of poly(methyl methacrylate) (PMMA) and polycarbonate (PC) filled with cerium-doped yttr…

2016

This paper reports on the thermomechanical properties and thermal degradation kinetics of poly(methyl methacrylate) (PMMA) and polycarbonate (PC) composites filled with cerium-doped yttrium aluminium garnet (Ce:YAG) at different contents ranging between 0.1 and 5 wt%, and prepared by melt compounding. The interaction between PMMA and the filler was much stronger than that between PC and the filler, and this resulted in a significant improvement in the dynamic mechanical properties of the PMMA composites. The presence of filler did not significantly increase the thermal stability of the PC, while an observable increase in the thermal stability was only observed at higher filler loadings for …

Morphology, interfacial interaction, and thermal degradation of polycarbonate/MCM-41 (nano)composites

2017

ABSTRACTThis article reports on the morphology, interfacial interaction, thermal stability, and thermal degradation kinetics of polycarbonate (PC)/mesoporous silica (MCM-41) composites with various MCM-41 contents, prepared by melt compounding. The composites with low filler loadings (<0.3 wt%) maintained their transparency because of the well dispersed MCM-41 particles, but at higher filler loadings the composites lost their transparency due to the presence of agglomerates. The presence of agglomerates decreased the thermal stability of PC due to the reduced effectiveness of the particles to immobilize the polymer chains, free radicals, and volatile degradation products.

Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.

2018

‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…

Preparation and characterization of Ce:YAG-PMMA and Ce:YAG-PC composites for white LED

2015

Polymeric composites of lanthanide-doped materials were considered as potential candidates for the development of white LED. Ce:YAG-PMMA and Ce:YAG-PC composites were prepared by melt compounding. The characterization was performed using transmission electron microscopy, X-ray diffractometry, thermogravimetry and photoluminescence spectroscopy. The effect of filler quantity, in the range 0.1-5 wt.%, on the morphology, optical and thermal properties was investigated.

GALACTOSE-DECORATED POLYMERIC CARRIERS FOR HEPATOCYTE-SELECTIVE DRUG TARGETING

2015

In this paper, the current available strategies to realize galactose-decorated nanostructured polymeric systems are summarized. These carriers are designed in order to obtain targeted drug delivery to hepatocytes via galactose (GAL) moieties, i.e., for the treatment of viral hepatitis or liver cancer that are the greater causes of global disability and mortality. Usually, the main followed strategy to obtain galactosylated polymeric carriers is to use galactosylated copolymers. The chemical modifications of preformed polymers with sugar-containing reagents is followed for obtaining lactosaminated human albumin, galactosylated phospholipid-polyaminoacid and polylactide (PLA)- polyaminoacid c…

Synthesis and characterization of nanostructured materials applied to energy devices

2011

Effect of environmental conditions on the durability of polycarbonate for the protection of cultural heritage sites.

2019

Polycarbonate is a good material for covering and protecting cultural heritage sites because of its durability, mechanical properties, and transparency. However, polycarbonate degrades under environmental weathering with a significant decrease of physical and mechanical properties and loss of transparency. In this work, the contemporary presence of ultraviolet irradiation and different temperature and moisture conditions have been taken into account to study the environmental degradation of this polymer with regard to its mechanical and optical properties. The photo-oxidation reactions cause a decrease in the molecular weight and the formation of many oxygenated species. The hydrolytic sci…

Ultrasounds and ionic liquids assisted methanolysis of polycarbonate: The route towards a more sustainable recycling

Influence of the modification, induced by zirconia nanoparticles, on the structure and properties of polycarbonate

2013

Melt compounding was used to prepare polycarbonate (PC)–zirconia nanocomposites with different amounts of zirconia. The effect of the zirconia loading, in the range of 1–5 wt.%, on the structure, mechanical properties and thermal degradation kinetics was investigated. The zirconia nanoparticle aggregates were well dispersed in the PC matrix and induced the appearance of a local lamellar order in the polycarbonate as inferred by SAXS findings. This order could be a consequence of the intermolecular interactions between zirconia and the polymer, in particular with the quaternary carbon bonded to the methyl groups and the methyl carbon as inferred from the NMR results. The presence of zirconia…