Search results for "composites"

Photo-stabilization of biopolymers-based nanocomposites with UV-modified layered silicates

2020

Abstract Eco-friendly in-situ stabilised biopolymer nanocomposites based on polyamide 11 (PA11) and polylactic acid (PLA) were prepared by melt mixing in the presence of a modified organo-montmorillonite clay containing a chemically-bound hindered amine UV-stabilising function, [(UV)OM-MMt]. Characterisation of the newly synthesised organo-modifier containing the reactive hindered amine (HAS) UV-stabilising function [(UV)OM] has confirmed a successful synthesis. The (UV)OM was then introduced into NaMMt through ion exchange reaction to prepare the UV stabiliser-bound organo-modified-MMt, [(UV)OM-MMt]. The in-situ stabilised PA11- and PLA- nanocomposites (PA11-(UV)OM-MMt and PLA-(UV)OM-MMt) …

Boron–nitrogen substituted dihydroindeno[1,2-b]fluorene derivatives as acceptors in organic solar cells

2019

The electrophilic borylation of 2,5-diarylpyrazines results in the formation of boron–nitrogen doped dihydroindeno[1,2-b]fluorene which can be synthesized using standard Schlenk techniques and worked up and handled readily under atmospheric conditions. Through transmetallation via diarylzinc reagents a series of derivatives were synthesized which show broad visible to near-IR light absorption profiles that highlight the versatility of this BN substituted core for use in optoelectronic devices. The synthesis is efficient, scalable and allows for tuning through changes in substituents on the planar heterocyclic core and at boron. Exploratory evaluation in organic solar cell devices as non-ful…

Solubilisation of multi walled carbon nanotubes by alpha-pyrene functionalised PMMA and their liquid crystalline self-organisation.

2008

alpha-Pyrene functionalised poly(methyl methacrylate) (PMMA) chains were synthesised by RAFT polymerisation and found to be highly efficient to solubilise and disentangle multi walled carbon nanotubes that can now self-organise as liquid crystalline phases in PMMA and PEG 400 matrices.

On the use of hydrotalcite in PLA based composites

2012

Fiber Post Removal: Comparative Study Using a New Post Concept

2009

Objectives: To evaluate the time required to remove endodontic posts made of quartz and glass fibers, and compare them to a new glass fiber post designed for easy removal on the basis of efficiency and tooth damages. Methods: 40 human single-rooted teeth were treated endodontically and randomly assigned to four fiber posts groups: 1) was restored with Premier#90 (Innotech); 2) with DT#2 Lightpost (Dentsply); 3) with Unicore#3 (Ultradent); 4) with a special, soft-cored “S” glass fiber post ER-Prosthetic#3 (Overfibers). An impression of the canal was taken prior post cementation. The posts were luted with Panavia F and adhesive (Kuraray). All the specimens were mounted in a dental simulation …

The role of POSS on the structure-properties relationship in Polystyrene based nanocomposites

2011

Impact on flavour release of the structure of composite gels containing polysaccharides: Example of the fruit préparations

2006

The main objective of this study was to understand the respective rôle of the structure of a food product and of the physicochemical interactions on flavour release. For that purpose, fruit préparations hâve been chosen as model matrices. Those matrices contain a polysaccharide as gelling agent, a cross-linked waxy corn starch (1.4%), a high sucrose content (35%), an acidic buffer and a strawberry aroma (17 molécules). Four matrices were developed by modifying either the composition or the concentration in gelling agent: two matrices of similar texture containing either LM pectin or carrageenan, and two carrageenan based matrices with différent gelled structures. In a first step; two comple…

Insights into the Maya Blue technology: greenish pellets from the ancient city of La Blanca.

2011

Financial support is gratefully acknowledged from the MEC Projects CTQ2011-28079-CO3-01 and 02 which are also supported with ERDF funds. Research was conducted within the "Grupo de anlisis cientifico de bienes culturales y patrimoniales y estudios de ciencia de la conservacion" Microcluster of the University of Valencia Excellence Campus. The authors would like to thank Dr. Isabel Solana (SCSIE, UV), Dr. Jose Luis Moya Lopez, and Manuel Planes Insausti (Microscopy Service UPV) for their technical support.

Dynamic properties of solvent confined in silica gels studied by broadband dielectric spectroscopy

2007

Abstract We report the results of a broadband (10−2–107 Hz) dielectric spectroscopy study on a solvent system (glycerol–water solution) confined in a porous silica matrix. The dielectric relaxation of the system is studied as a function of both temperature (120–280 K) and solvent composition (0–36 glycerol molar percentage), at constant matrix composition. Our data show that glycerol–water systems confined inside silica gel are characterized by a very complex dynamics quite different from that observed in solution, thus indicating that confinement may deeply modify solvent dynamics. Indeed in addition to the relaxation processes similar to those occurring in bulk samples, new dielectric rel…

Digital estimators of relaxation spectra

2007

Determination of the distribution of relaxation times (DRT) from a wide variety of the time- and the frequency-domain material functions, such as polarization current and charge, real and imaginary parts of complex dielectric permittivity and complex dielectric modulus, the appropriate mechanical and magnetic counterparts is generalized as a filtering problem on a logarithmic time or frequency scale. Algorithms of the appropriate digital DRT estimators are derived. A novel regularization strategy is proposed based on choosing sampling rate for the input data, which ensures acceptably low random error of the recovered spectra. Optimum frequency ranges and sampling rates are found for determi…