0000000000182003
AUTHOR
D. Curto
SHEAR BEHAVIOUR OF MOLTEN LINEAR LOW DENSITY POLYETHYLENE.
The rheological behaviour of molten polyethylene has been widely studied especially with respect to the different structure of the high density and low density samplesI–I0. In particular it is well known that the presence in the LDPE of long chain branching alters dramatically the whole flow curve, the activation energy, the die-swell, the instability phenomena, etc.
Recycling of dry and wet polyamide 6
Recycling of polycondensation polymers can give rise to secondary materials with good mechanical properties only if a careful drying is carried out before the melt reprocessing operations. The presence of humidity provokes the hydrolytic chain scission of the macromolecules and the consequent decrease of molecular weight and properties. In this work, the drying step was substituted by the addition of an antioxidant that is able to protect the macromolecules because it is the autioxidant is more prone to hydrolysis, thus removing the water from the melt. The mechanical properties of polyamide 6 reprocessed more times in wet conditions and in the presence of this stabilizer are even better th…
Near 100% Renewable Island with sea wave energy. The case study of Pantelleria in Mediterranean sea
The first aim of this work is to explore the possibility of the transition of a real islanded network from one that is “fuel-based” to a “renewable-based” one. This transition is analysed for the real MV/LV distribution system of the island of Pantelleria, in the Mediterranean Sea. Particularly, this work is focused on a Renewable source nowadays totally unused: wave energy. Thanks to the innovative generator prototype designed by Department of Energy of University of Palermo (Italy), wave energy is able to represent a primary source for the production of electric energy in the Mediterranean islands. The procedures applied in the present article, as well as the main equations used, are the …
The rheological behaviour of HDPE/LDPE blends. II. Die swell and normal stresses
Die swell data are presented for different high-density/low-density polyethylene blends. The data relating to samples with frozen-in stresses are represented, collected as a function of the usual operational parameters (L/D ratio, flow rate, temperature). Data obtained with annealed samples are used to derive, through a theoretical approach, normal stresses. Die Strahlaufweitung wurde fur verschiedene Mischungen aus Polyethylenen hoher und niedriger Dichte gemessen. Die an Proben mit eingefrorenen Spannungen erhaltenen Werte wurden in Abhangigkeit von technologischen Parametern (Lange/Durchmesser-Verhaltnis, Fliesgeschwindigkeit, Temperatur) dargestellt. An getemperten Proben gemessene Wert…
Recycling of degraded polyethylene: Blends with nylon 6
Abstract Recycled polyethylene can be used for blending with nylon to obtain blends with mechanical properties better than those of blends with virgin polyethylene. Moreover, the mechanical properties of these blends are very close to and, in some cases, better than those of the pure nylon and those of blends made with functionalized polyolefines. The carbonyl groups of the photo-oxidized polyethylene react with amino end-groups of nylon 6, giving rise to graft copolymers which act as interfacial agents between the two incompatible phases. Large degrees of photo-oxidation of the polyethylene and intense mixing improve the properties of the blends.
Extensional flow of HDPE/LDPE blends
Elongational viscosity data, obtained through the converging flow analysis by Cogswell, are presented for two types of HDPE/LDPE blends at various compositions and different temperatures. The results relative to the homopolymer parents compare favourably with literature data obtained also with different and more sophisticated techniques. Those relative to blends show peculiar features for the two cases: when the newtonian viscosity of the LDPE is higher all the blends show a behaviour typical of the LDPE with a maximum in η el /η0 enhanced at small percentage of HDPE; when the newtonian viscosity of the LDPE is similar to that of the HDPE there is only a gradual change in the properties.
Flow properties of low density/linear low density polyethylenes
Rheological data have been collected both in shear and non-isothermal elongational flow on three different types of blends, made from one low density polyethylene sample and three linear low density polyethylene samples. In addition to the flow curves, data are presented on the extrudate-swell phenomenon, on the instability arising in capillary flow and on the tensile behavior in the molten state.
Renewable energy sources for energy consumption needs of Malta Island in Mediterranean sea
The main purpose of this paper is to analyse the energetic condition of the Maltese islands and its electrical energy production, focusing on the employment of Renewable Energies in order to increase its energy independence. The main renewable source here proposed is wave energy: thanks to its strategic position, Malta will be able to produce electrical energy using an innovative type of Wave Energy Converter (WEC) based on the prototype of linear generator realized by University of Palermo. The use of this new technology will be able to cut down the electrical energy production from traditional power plants and, consequently, the greenhouse gases emissions (GHG). The procedures applied in …
The rheological behaviour of HDPE/LDPE blends
The rheological behaviour of three types of HDPE/LDPE blends at several compositions (various weight percentages of LDPE) has been studied with the aid of a capillary rheometer and three different capillaries.
The rheological behavior of HDPE/LDPE blends 4. Instability phenomena in capillary flow
Experimental data, relative to instability phenomena in capillary flow, have been collected for HDPE/LDPE blends already characterized from a rheological viewpoint. The data comprise morphological observations as well as the determination of critical parameters as a function of the blend composition and of the processing conditions.
Sea wave energy to produce Hydrogen for public transport in Trapani (Italy)
The coupling of renewable energy and hydrogen technologies represents in the mid term a very interesting way to match the tasks of increasing the reliable exploitation of wind and sea wave energy introducing clean technologies in the transportation sector. This paper presents a feasibility study of two plants for the production, storage and distribution of hydrogen for Public transportation facilities in the West Sicily. In these plants the energy needs for the process is generated by a wind farm and/or a sea wave farm. All the buses will be equipped with a fuel-cell. A first economic analysis is presented together with the assessment of the avoidable greenhouse gas emissions during the ope…
Blends of nylon 6 with a polyethylene functionalized by photooxidation
An easy and cheap method to prepare functionalized polyethylene is reported in which polyethylene is photooxidized and then melt-blended with nylon. Structural, rheological, and mechanical modifications indicate that carbonyl, formed during photooxidation, and amine groups react giving rise to copolymers which stabilize the blends. Photooxidized polyethylene from waste could be very effective in preparing polyethylene/polyamide blends with improved properties. This new approach improves over current methods in which compatibilization of polyolefines and polyamides is mostly performed by reacting functionalized polyolefines with polyamides in molten state. The functionalization is achieved b…