Search results for " polymers"

Conductive polymer composites based on cyclic butylene terephtalate oligimers and carbon fibers

2007

Processing and characterization of blends of fluoroelastomers with semirigid liquid crystal polymers

1996

Fluoroelastomers (FEs) usually have working temperatures above 150 degrees C and a great resistance to aggressive agents such as oils, fuels, aliphatic and aromatic solvents, steam, moderate acid, and basic environments. Liquid crystal polymers (LCPs) can be effective processing aids and reinforcing agents for elastomers. These characteristics are very attractive to lower melt viscosity and to stiffen and strengthen the final product through a simple blending. Among the LCPs, the semirigid LCPs seem the most appealing for blending with flexible thermoplastics (FTs) because their processing temperatures can be arranged to be in the same processing temperature range of FTs and because the pre…

Polymer-coated Nanolimes Dispersions for Reduction, Deacidification and Consolidation of Ancient Paper

Nanolimes have been widely explored as nanomaterial for cultural heritage preservation. In particular, they have shown interesting properties to contrast the ageing of manuscripts, books and artistic works, opening up the possibility to store such items in a good quality state for longer. In the present work we reported an innovative nanolime-based formulation for paper restoration, which includes in its composition a reducing agent and a fibers consolidator as well. To formulate an efficient product, we deeply investigated the cellulose oxidation process with a multi-technique approach. The here presented formulation consists in a hydroalcoholic ternary dispersion of nanolimes coated with …

Physical and antibacterial properties of PLA electrospun mats loaded with carvacrol and nisin

2022

Functional, biopolymeric electrospun structures for the controlled release of antimicrobial agents are gaining in-creasing interest in food packaging applications. In this study, the physical and antibacterial performances of ternary systems composed of polylactic acid (PLA) electrospun mats loaded with 20 wt% of different relative amounts of carvacrol (CRV) and a commercial nisin formulation (Nis) were assessed. Scanning electron micrographs displayed micro-scaled fibers with different diameter size distributions depending on the relative concentrations of the additives. The PLA/CRV/Nis membranes??? wettability was affected by the relative amount of CRV and Nis loaded, switching from hydro…

Sustainable Materials Containing Biochar Particles: A Review

2023

The conversion of polymer waste, food waste, and biomasses through thermochemical decomposition to fuels, syngas, and solid phase, named char/biochar particles, gives a second life to these waste materials, and this process has been widely investigated in the last two decades. The main thermochemical decomposition processes that have been explored are slow, fast, and flash pyrolysis, torrefaction, gasification, and hydrothermal liquefaction, which produce char/biochar particles that differ in their chemical and physical properties, i.e., their carbon-content, CHNOS compositions, porosity, and adsorption ability. Currently, the main proposed applications of the char/biochar particles are in …

The Use of Waste Hazelnut Shells as a Reinforcement in the Development of Green Biocomposites.

2022

Biodegradable Mater-Bi (MB) composites reinforced with hazelnut shell (HS) powder were prepared in a co-rotating twin-screw extruder followed by compression molding and injection molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal and rheological properties of MB/HS biocomposites were studied. Rheological tests showed that the incorporation of HS significantly increased the viscosity of composites with non-Newtonian behavior at low frequencies. On the other hand, a scanning electron microscope (SEM) examination revealed poor interfacial adhesion between the matrix and the filler. The thermal property results indicated that HS could …

Nanocarbon broadband analysis, temperature dependent dielectric properties and percolation thresholds

2013

The results of a broadband dielectric investigation of multi-walled CNT (MWCNT)/epoxy resin composites in wide temperature range from room temperature to 450 K are reported. Far below the percolation threshold (0.25 wt% MWCNT) the dielectric properties of the composite are mostly determined by alpha relaxation in pure polymer matrix. Close to the percolation threshold the composite shows the negative temperature coefficient (NTC) effect in the temperature region, where the pure polymer matrix becomes conductive. The activation energy increases with the MWCNT concentration far below the percolation threshold and decreases close to it (1.5 wt% MWCNT). The dielectric analysis of the MWCNT/epox…

Polymer-based 'green' composites

2009

Biodegradable polymer-wood flour composites: main properties and biodegradability

2009

During the last years, a considerably increasing rate of attention has arisen on biodegradable polymers. In the meanwhile, the use of wood-plastic composites (WPC) has grown in importance, especially in the United States. The combination of biodegradable polymers and wood-based fillers allows obtaining the typical advantages achievable with the use of WPCs, with the further advantage of the biodegradability and compostability of the matrix (and not only of the filler). In this work, the characterization and the biodegradability assessment of Mater-Bi®-wood flour composites have been carried out.

Photoelectrochemical Synthesis of Polypyrrole on Anodic Ta2O5 Films

2007

Polypyrrole film was photoelectrochemically grown on insulating Ta2O5 anodic film in acetonitrile solution. A characterization by photocurrent spectroscopy PCS of metal/oxide/polypyrrole interface was carried out. The PCS results suggest that a metallic-like PPy is formed under illumination at constant anodic potential. By polarizing the polypyrrole at cathodic potentials a photocurrent spectrum typical of p-type semiconducting film was recorded. A scanning electron microscopy study of PPy surfaces solution side and oxide side allowed us to obtain information on the morphology of the polymer as well as a rough estimate of the film thickness and of the diameter of PPy globules at the two int…