Search results for "sites"

Low-temperature single crystal X-ray diffraction and high-pressure Raman studies on [(CH3)2NH2]2[SbCl5]

2007

The structure of bis(dimethylammonium) pentachloroantimonate(III), [(CH{sub 3}){sub 2}NH{sub 2}]{sub 2}[SbCl{sub 5}], BDP, was studied at 15 K and ambient pressure by single-crystal X-ray diffraction as well as at ambient temperature and high pressures up to 4.87(5) GPa by Raman spectroscopy. BDP crystallizes in the orthorhombic Pnma space group with a=8.4069(4), b=11.7973(7), c=14.8496(7) A, and Z=4; R{sub 1}=0.0381, wR{sub 2}=0.0764. The structure consists of distorted [SbCl{sub 6}]{sup 3-} octahedra forming zig-zag [{l_brace}SbCl{sub 5}{r_brace}{sub n}]{sup 2n-} chains that are cross-linked by dimethylammonium [(CH{sub 3}){sub 2}NH{sub 2}]{sup +} cations. The organic and inorganic substr…

Durability of multi-phase polymer based nanocomposites

2010

Influence of the morphology on the photo-oxidation behaviour of polymer based nanocomposites

2011

The use of in-line quantitative analysis to follow polymer processing

2009

In this work it is presented three applications of real time analysis during extrusion process using an optical device developed by our research group, which applies the concepts of light extinction. Monitoring of polymer blends morphology takes place to infer data concerned to dispersed phase size and concentration. The detector also enables information about melting temperature of polymer during extrusion and the level of viscous heating, and the exfoliation step during processing of a polymer-clay nanocomposite.

Characterization and biodegradability of biodegradable polymer-wood flour composites

2008

Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

2021

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the gr…

Recycling of Thermoset Materials and Thermoset-Based Composites: Challenge and Opportunity

2022

Thermoset materials and their composites are characterized by a long life cycle with their main applications in aircrafts, wind turbines and constructions as insulating materials. Considering the importance of recovery and valorization of these materials at their end-of-life, avoiding landfilling, the interest concerning their recycling grows continuously. The thermoset materials and their composites, to be successfully recovered and valorized, must degrade their three-dimensional structures and recover the mono-oligomers and/or fillers. The thermoset materials could successfully degrade through thermal treatment at different temperatures (for example, above 1000 °C for incineration, ca. 50…

Performances Recovery of Flax Fiber Reinforced Composites after Salt-Fog Aging Test

2022

In the present paper, the performance recovery under conditions of discontinuous exposure to a marine environment of a natural fiber-reinforced composite (NFRC) reinforced by flax fibers was assessed. In particular, this laminate was initially exposed to salt-fog for 15 and 30 days, and then stored in a controlled air condition for up to 21 days. The flax fiber-reinforced composite showed coupled reversible and irreversible aging phenomena during the wet stage, as well as evidencing a significant mechanical recovery during the dry stage. Unlike the stiffness, the laminate showed a noticeable recovery of its flexural strength. This behavior affected the composite material toughness. A simpli…

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

2010

Étude d'inclusions végétales dans des tessons de poterie ou des matériaux de construction

2005

Vegetal inclusions embedded in clayey materials (cob, ceramic, mudbrick) are investigated by using impregnation of the porous material with a fluorescent polymer. The micro-casting of the porosity is exploited by following two ways. Sections of the treated samples are examined under UV-light, showing vegetal structures amenable to a botanical identification and quantification. Moreover, micro-casts embedded in the mineral matrix have been successfully sorted. This new application is a tool to study archaeological samples previously not amenable to the work of archaeobotanists and to expand their field of investigation.