Search results for "extrusion"
showing 10 items of 142 documents
Reprocessing of PLA/graphene nanoplatelets nanocomposites
2017
This work reports a study on the effect of multiple reprocessing on the properties of poly(lactic acid) (PLA) filled with graphene nanoplatelets (GnP) compared to the melt reprocessed neat polymeric matrix. In particular, morphological, X-Ray Diffraction and Micro-Raman analyses, intrinsic viscosity measurements, thermal, rheological and mechanical tests were carried out on materials reprocessed up five times by means of a single screw extruder. The results indicated that the presence of GnP decreased the degradation rate as a function of the reprocessing cycles in comparison with the neat PLA that, on the contrary, showed a more drastic reduction of the molecular weight. Moreover, the repr…
Degradation and Recycling of Films Based on Biodegradable Polymers: A Short Review
2019
The environmental performance of biodegradable materials has attracted attention from the academic and the industrial research over the recent years. Currently, degradation behavior and possible recyclability features, as well as actual recycling paths of such systems, are crucial to give them both durability and eco-sustainability. This paper presents a review of the degradation behaviour of biodegradable polymers and related composites, with particular concern for multi-layer films. The processing of biodegradable polymeric films and the manufacturing and properties of multilayer films based on biodegradable polymers will be discussed. The results and data collected show that: poly-lactic…
Evolution of the morphology and characterzation of compatibilized PBT/EVA blends prepared by reactive extrusion
2006
In this work, the possibility of preparing compatibilized blends of poly(butylene terephthalate) (PBT) and an ethylene vinyl acetate (EVA) copolymer by reactive extrusion in the presence of an ethylene acrylic acid copolymer (EAA) and a bisoxazoline compound (PBO) as compatibilization promoters has been studied. In addition, the evolution of the morphology of the blends under different annealing conditions in the presence and absence of the compatibilizing promoters has been studied. Binary blends of PBT and EVA showed behavior typical of incompatible blends with a gross morphology and bad mechanical performance. The situation was however different for ternary PBT/EVA/EAA and especially for…
Effect of the additive level and of the processing temperature on the re-building of post consumer pipes from polyethylene blends
2007
Abstract One of the main shortcomings of the mechanical recycling is that the properties of the secondary materials are generally sensibly inferior with respect to the virgin ones. This feature implies, for sure, that they cannot be used for the same technological application but also other uses of the secondary material are impossible. The aim of this work is to study the re-building of recycled post-consumer pipes, made of a blend of different polyethylenes, by re-processing in the presence of a nitroxyl compound as radical generator. The processing temperature and the additive concentration have been varied in order to study the effect of these parameters on the final properties. The mec…
Recycling of a Biodegradable Polymer Blend
2020
Mechanical recycling is one of the possible ways to enhance the value of postconsumer plastic materials. However, the final performance of the recycled material will strongly depend on the quality of the selection made on the recycled product and on the degradation of the properties. In this context, the present study examines the effect of reprocessing for five successive extrusion cycles on the rheological, mechanical and thermal properties of a poly(butylene adipate-co-terephthalate) (PBAT)-based blend on samples reprocessed in both dry and wet conditions. The results showed that when the sample was processed after drying, degradation of the material was less than when it was processed i…
Effect of the processing techniques on the properties of ecocomposites based on vegetable oil-derived Mater-Bi® and wood flour
2009
Polymer composites based on biodegradable polymers and natural-organic fillers are becoming more and more important because of their interesting properties in terms of environmental impact, manufacturing cost, and esthetic features. In particular, the use of biodegradable polymer matrices allows obtaining a full biodegradability. One of the most interesting biodegradable polymer families is the Mater-Bi® one. In this work, we investigated the processability, the influence of different processing techniques, and the influence of the filler particle size on the properties of Mater-Bi/wood flour composites. Injection molding caused a partial degradation of the macromolecular chains, whereas si…
Light Scattering as an Easy Tool to Measure Vesicles Weight Concentration
2020
Over the last few decades, liposomes have emerged as promising drug delivery systems and effective membrane models for studying biophysical and biological processes. For all applications, knowing their concentration after preparation is crucial. Thus, the development of methods for easily controlling vesicles concentration would be of great utility. A new assay is presented here, based on a suitable analysis of light scattering intensity from liposome dispersions. The method, tested for extrusion preparations, is precise, easy, fast, non-destructive and uses a tiny amount of sample. Furthermore, the scattering intensity can be measured indifferently at different angles, or even by using the…
Improved hydrophobicity of inorganic–organic hybrid mesoporous silica with cage-like pores
2013
International audience; Hydrophobic ordered mesoporous silica particles with cage-like pores (SBA-1 type) were prepared through co-condensation of phenyltriethoxysilane (PhTES) and tetraethylorthosilicate (TEOS) at different TEOS/PhTES molar ratios. It is shown that the hydrophobic character of the particles is enhanced by increasing the phenyl loading (decreasing the TEOS/PhTES molar ratio) and that it could be further enhanced by subsequent trimethylsilyl (TMS) grafting on remaining silanol groups (TMS-PhSBA-1 sample). This increase of hydrophobicity has been evidenced on the internal surface (mesoporosity) of the particles using water adsorption and, on the external surface of the partic…
Evaluation of conventional, protaper hand and protaper rotary instrumentation system for apical extrusion of debris, irrigants and bacteria- An in vi…
2017
Background: Endodontic instrumentation carries the risk of over extrusion of debris and bacteria. The technique used and the type of instrumentation influences this risk. Aim: The purpose of this study was to evaluate and compare the K-file, ProTaper hand and ProTaper rotary instrumentation systems for the amount of apically extruded debris, irrigant solution and intracanal bacteria. Design: Experimental single blinded randomized type of in vitro study with sample of 30 single rooted teeth. Endodontic access cavities were prepared and the root canals were filled with the suspension of E. faecalis. Myers and Montogomery Model was used to collect apically extruded debris and irrigant. Canals …
Factors Influencing Bonding Mechanics in FSW of AA5754
2011
Solid state bonding recurs in several manufacturing processes, as extrusion of hollow profiles and solid welding processes. Among the latter, Friction Stir Welding (FSW) is nowadays of particular industrial interest because of the specific advantages with respect to the classic welding technologies. Proper conditions of pressure, temperature, strain and strain rate are needed in order to get the final effective bonding. In the paper the authors compare different solid state bonding conditions obtained at the varying of the main process parameters in FSW of butt joints of AA5754 aluminum alloys. The experimental results are compared with the numerical ones from a FEM model previously develop…