Search results for "Pact"
showing 10 items of 2355 documents
Rheological Behaviour, Mechanical Properties and Processability of Biodegradable Polymer Systems for Film Blowing
2017
Films for agricultural or packaging applications are typically made of low density polyethylene (LDPE). They are produced through the film blowing process, which requires the use of polymers with suitable rheological properties. Furthermore, the short shelf-life which is often related to many packed products leads to huge amounts of plastic-based wastes. This suggests the use of biodegradable and/or compostable polymers in replacement for traditional ones. To this regard, only few data exist on the rheological properties of biodegradable polymers undergoing film blowing processing. In this work, a detailed investigation on the rheological, mechanical and processability behaviour of some bio…
Mechanical behaviour of Mater-Bi/wood flour composites: a statistical approach
2008
Interest in biocomposites (lignocellulosic filled biopolymers) started in the 90s, due to environmental advantages, related to the full biodegradability of both matrix and filler, economical issues (organic fillers usually come from sawmill or agriculture wastes) and aesthetical issues (wood filled biopolymers could be particularly pleasant if used for indoor furnishing and automotive interior). In this work, a method for a systematic study of the properties of Mater-Bi®/wood flour composites is presented. A two-level full factorial model was built. It allows investigating the effects of multiple operative variables on the observed properties, their contributions, their optimal combinations…
Impact of operation condition on temperature distribution in single cell of polymer electrolyte fuel cell operated at higher temperature than usual
2016
For improving performance of the stationary Polymer Electrolyte Fuel Cell (PEFC) system, the cell operating temperature up to 90°C will be preferred in Japan during the period from 2020 to 2030. To understand the operation of the PEFC system under relatively high temperature conditions, detail heat and mass transfer analysis is required. The main focus of this study is to analyze the PEFC performance under operational conditions, such as initial operational temperature of cell (Tini), relative humidity of supply gas, and the cathode gas type, temperature distribution in a cell of PEFC (using Nafion membrane) under relatively higher operating temperature conditions. The in-plane temperature …
Reprocessing of Poly(Vinyl Chloride), Polycarbonate and Polyethyleneterephthalate
1998
Poly ethyleneterephthalate — PET- and Poly(vinyl chloride) — PVC — are two of the most frequently encountered polymers in post-consumer plastics. In particular, these polymers can be used for manufacturing the same products (bottles, for example) and therefore are often found in the same stream, even when the collection is done with separation. The recycling of PET and PVC is usually carried out by separating them and reprocessing the two homogeneous polymers. Indeed, the heterogeneous recycling of two polymers is at present almost impossible because of many problems: as their melting points are very different, at the processing temperature of PET severe degradation phenomena of PVC take pl…
Reprocessing and Properties of Homopolymer Blends of Virgin and Recycled Polymers
1998
The blends of the same virgin and recycled polymer, (homopolymer or “monopolymer” blends), show rheological and mechanical properties in most cases between those of the two components athough, in general, lower than those expected on the basis of additivity rules. In some cases, however, a minimum observed in some property versus composition curves is correlated with the change of the crystalline morphology induced by structural differences of the two components and due to different molecular weights and, in particular, the presence of oxygenated groups. In this chapter, the main properties of some homopolymer blends will be reviewed by considering, in particular, the influence of compositi…
Effect of adding new phosphazene compounds to poly(butylene terephthalate)/polyamide blends. II: Effect of different polyamides on the properties of …
2006
Poly(butylene terephthalate) (PBT) and a sample of polyamide have been melt processed in the presence of two new phosphazene compounds, namely 2,2-dichloro-4,4,6,6-bis[spyro(2',2"-dioxy-1',1"-biphenyl)]cyclotriphosphazene (2Cl-CP) and 2,2-bis(2-methoxy-4-methyleneoxy-phenoxy)-4,4,6,6-bis[spyro(2',2"-dioxy-1',1"-biphenyl)]cyclophosphazene (CP-2EPOX). The blends were prepared by using polyamide 6 (PA6) and polyamide 6,6 (PA66) in 25/75 and 75/25 w/w compositions by using a co-rotating twin-screw extruder. The materials have been completely characterized from a mechanical, rheological, and morphological point of view. The results indicate that the additives used cause an increase of the ruptur…
Molecular modifications—Mechanical behaviour relationships for gamma irradiated LLDPE/PA6 blends
1994
Abstract The molecular modifications, due to γ radiation under vacuum, of linear low density polyethylene/polyamide 6 blends are presented and related to their mechanical behaviour. Solubility and melt viscosity tests indicate that in blends the polyethylene component undergoes mainly crosslinking phenomena, whereas the main effect on polyamide is chain branching. According to these molecular modifications, the most relevant effect is the increase of the tensile modulus for the polyethylene rich blends and the increase of the impact strength for the polyamide rich blends.
Use of stable isotopes to investigate dispersal of waste from fish farm as a function of hydrodynamics.
2006
Stable isotopes were used to examine differential effects of fish farm waste on the water column and sediments. To achieve this objective, we chose 3 marine fish farms located along the coast of Sicily (Mediterranean Sea) as point-source disturbances, and a control area. The hypothesis that carbon and nitrogen isotope composition of particulate (POM) and sedimentary (SOM) organic matter varied with increasing distance (from cages to 1000 m) was tested at 3 levels of hydrodynam- ics: low (mean velocity of current (MVC) ~12 cm s -1 ), intermediate (MVC ~22 cm s -1 ), and high (MVC ~40 cm s -1 ). Different isotopic signals from allochthonous (fish waste) over natural (phytoplankton, terrigenou…
Environmental impact of mining activities on the Hermioni area, Greece
1993
Publisher Summary This chapter investigates the environmental impact of mining activities in the Hermioni area, Greece, including the offshore area. A chemical analysis of sediments associated with diabase lavas in the Hermioni mine area has shown significant enrichments in Fe, Mn, Zn, Cu, and As relative to normal pelagic clays. Marked geographic compositional variations within the Hermioni area have been observed, the highest metal enrichments found at Baroutospelia. Mineralogically the Fe–Mn sediments contain hematite, quartz, and minor amounts of illite, smectites, and feldspars. A chemical analysis of sulfide ore samples showed that the Hermioni ores are Cu-rich pyrites, always contain…
Processing and Mechanical Properties of Natural Fiber Reinforced Thermoplastic Starch Biocomposites
2007
Natural fiber reinforced starch polymers are processed by compression molding. Potato, sweet potato, and corn starch are used as matrices. Three types of natural fibers, namely sisal, jute, and cabuya, are used in concentrations varying from 2.5 to 12.5% w/w in the composites. Different plasticizers are used for the starch polymers, such as water and glycerol. Mechanical properties are assessed by tensile and impact tests. In both cases, improved mechanical properties are obtained at increasing fiber contents. Tensile strength appears to be markedly improved with the addition of 10% by weight of sisal fibers, while the best results for impact strength are obtained for cabuya fibers.